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  1. The use of Portland cement in the repair of mandibular fractures in rats Uso de cimento Portland no reparo de fratura mandibular em ratos

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    Reginaldo Inojosa Carneiro Campello

    2011-12-01

    Full Text Available PURPOSE: To evaluate the bone healing of mandibular fractures following the use of Portland cement. METHODS: Thirty-two male Wistar rats were divided into control and experimental groups. In the control group the rats were submitted to a mandibular fracture, which was reduced, and the soft tissues were sutured. In the experimental group the rats had the mandibular fracture reduced and maintained with the Portland cement. The animals were euthanized 7 and 21 days after surgery by injecting a lethal dose of anesthetic. The following variables were studied: weight of the animals, radiographic images, histopathological features and time of surgery. RESULTS: A weight loss was observed in the specimens of both groups at the different times of evaluation, a greater difference in weight before and after surgery being found in the experimental group, which was statistically significant (p OBJETIVO: Avaliar a reparação óssea de fratura mandibular após o uso do cimento Portland (CP. MÉTODOS: Trinta e dois ratos machos Wistar foram divididos em grupo controle e grupo experimental. No grupo controle os ratos foram submetidos à fratura, redução e manutenção dos seguimentos com sutura dos tecidos moles. No grupo experimental foram submetidos a fratura, redução e manutenção dos segmentos fraturados com CP e sutura dos tecidos. Os animais foram eutanasiados com sete e 21 dias de pós-operatório através da injeção de dose letal dos anestésicos adotados. As variáveis estudadas foram: peso dos animais, avaliação tomográfica, avaliação histológica e tempo cirúrgico. RESULTADOS: Perda de peso foi observada nos espécimes de ambos os grupos nos diferentes intervalos de tempo considerados, sendo maior a diferença de peso antes e após cirurgia para o grupo experimental, que foi estatisticamente significante (p<0,05; p=0,041. Do ponto de vista histológico para a margem de erro fixada (5,0% as duas únicas diferenças significativas (p<0

  2. Portland cement with additives in the repair of furcation perforations in dogs Cimento Portland com aditivos na reparação de perfurações radiculares em cães

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    José Dias da Silva Neto

    2012-11-01

    Full Text Available PURPOSE: To evaluate the use of Portland cements with additives as furcation perforation repair materials and assess their biocompatibility. METHODS: The four maxillary and mandibular premolars of ten male mongrel dogs (1-1.5 years old, weighing 10-15 kg received endodontic treatment (n=80 teeth. The furcations were perforated with a round diamond bur (1016 HL. The perforations involved the dentin, cementum, periodontal ligament, and alveolar bone. A calcium sulfate barrier was placed into the perforated bone to prevent extrusion of obturation material into the periradicular space. The obturation materials MTA (control, white, Type II, and Type V Portland cements were randomly allocated to the teeth. Treated teeth were restored with composite resin. After 120 days, the animals were sacrificed and samples containing the teeth were collected and prepared for histological analysis. RESULTS: There were no significant differences in the amount of newly formed bone between teeth treated with the different obturation materials (p=0.879. CONCLUSION: Biomineralization occurred for all obturation materials tested, suggesting that these materials have similar biocompatibility.OBJETIVO: Avaliar o uso de cimentos Portland aditivados na reparação de perfurações radiculares e a biocompatibilidade destes materiais. MÉTODOS: Oitenta pré-molares, quatro da arcada dentária superior e quatro da arcada inferior de 10 cães machos, sem raça definida, com idade em torno de um a um ano e meio, pesando entre 10 e 15 kg foram submetidos a tratamento endodôntico, sendo realizadas perfurações nas furcas com broca de diamante 1016 HL. A cavidade envolveu dentina e cemento, como também periodonto e o osso alveolar. Na porção óssea da obturação, barreira de sulfato de cálcio foi utilizada evitando extravasamento do cimento para o espaço periodontal. Foi realizada a distribuição randomizada dos cimentos MTA (controle, Portland tipo II, Portland tipo V e

  3. Estudo clínico e radiográfico do formocresol de Buckley diluído a 1/5 e do cimento Portland utilizados para pulpotomia em dentes decíduos humanos

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    Ana Paula Camolese Fornetti

    2007-01-01

    O objetivo deste estudo foi comparar a eficácia clínica e radiográfica do formocresol de Buckley diluído a 1/5 e do cimento Portland como agentes capeadores pulpares em dentes decíduos humanos acometidos por cárie extensa. Sessenta e oito molares decíduos inferiores de 52 crianças com idades entre 5 e 9 anos foram criteriosamente selecionados. Os dentes foram aleatoriamente divididos nos grupos formocresol ou cimento Portland e tratados pela técnica convencional de pulpotomia. Após a remoção ...

  4. Avaliação da atividade pozolânica da cinza pesada moída em pastas de cimento Portland

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    Pilar,Ronaldo

    2012-01-01

    Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Civil O uso de adições minerais finamente moídas em substituição parcial do clínquer é prática comum na produção de cimento Portland. Normalmente estas substituições estão amparadas por razões técnicas, econômicas e ambientais. Embora já se tenha conhecimento de uma vasta gama de materiais que possuem propriedades pozolânicas, ainda existem alguns com grande disponib...

  5. Potencialidades de um caulim calcinado como material de substituição parcial do cimento portland em argamassas Potentialities of a calcined kaolin as material of partial replacement of portland cement in mortars

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    Marilia P. de Oliveira

    2006-06-01

    Full Text Available A utilização de argilas calcinadas na forma de metacaulinita, como material pozolânico para argamassas e concretos, tem recebido atenção considerável nos últimos anos. Este trabalho objetivou avaliar o desempenho mecânico de argamassas, nas quais foi utilizado um caulim calcinado proveniente do Estado da Paraíba, como material de substituição parcial do cimento Portland. Utilizaram-se duas finuras do caulim: passando nas peneiras ABNT 200 (0,074 mm e 325 (0,044 mm e calcinados nas temperaturas de 700, 800 e 900 ºC pelo tempo de 2 h. As amostras foram caracterizadas através de análise química, análise térmica diferencial, difração de raios-X e área específica. Obteve-se o índice de atividade pozolânica com a cal e o cimento Portland. O percentual de substituição adotado foi de 0, 10, 20, 30 e 40%. A relação aglomerante: areia foi de 1:1,5 e a relação água/aglomerante fixada igual 0,4. O efeito da substituição parcial do cimento na argamassa foi avaliado através da resistência à compressão simples, nas idades de 7, 28 e 90 dias. As argamassas estudadas apresentaram resistência superior em relação à da referência, até o nível de 30% de substituição.The use of burnt clays, in the metakaolin form, as pozzolanic material for mortars and concretes has received a remarkable attention in the last years. This paper aimed to evaluate the mechanical property of mortars, in which a calcined kaolin originating from the State of Paraiba, was used as partial cement replacement material. Two finess of the kaolin were used: ABNT 200 (0.074 mm and 325 (0.044 mm and burnt at temperatures of 700, 800 and 900 ºC for a period of 2 h. Both materials were characterized by chemical analysis, differential thermal analysis, X-ray diffraction, specific area tests. The pozolanic activity index was obtanied using lime and cement Portland. The amounts of replacement were 10, 20, 30 and 40%, besides the reference mortar. The binder

  6. Efeito da aplicação do poliestireno sulfonado (PSSNa como aditivo em argamassas e concretos de cimento Portland CPV32 Effect of PSSNa as admixture in mortars and concrete of cement portand CPV32

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    Betina Royer

    2005-03-01

    Full Text Available Neste trabalho foi investigado o uso do Poliestireno sulfonado (PSSNa, produzido a partir de copos plásticos descartáveis de Poliestireno (PS, como aditivo em argamassas e concretos de cimento Portland CPV32. A avaliação do PSSNa como aditivo foi baseada em ensaios de fluidez e resistência mecânica à compressão de corpos de prova. Foi observado, em argamassas com relação água/cimento (a/c de 0,48, um aumento na fluidez com o aumento das porcentagens de PSSNa (0,25 a 1,00%. A adsorção do PSSNa sobre as partículas de cimento melhora a dispersão dos componentes da argamassa, aumentando a resistência mecânica à compressão dos corpos de prova após a cura. A aplicação do PSSNa em concreto apresentou o mesmo efeito. O abatimento do concreto sem PSSNa foi de 50 mm, atingindo cerca de 200 mm com o uso do polieletrólito. Devido à elevada plasticização observada é possível empregar o PSSNa como aditivo redutor de água. Foi produzido um concreto com o mesmo abatimento da referência sem aditivo reduzindo-se a quantidade de água em 20,8%. O ganho de resistência mecânica à compressão obtido foi de 21,5 e 26,3 %, respectivamente aos 7 e 28 dias de cura. Estes resultados mostraram que soluções de PSSNa podem atuar eficientemente como aditivo superplastificante ou redutor de água em argamassas e concretos.In this work an investigation was made of the effects from adding PSSNa, obtained from disposable polystyrene (PS cups, as admixture agent in mortars and concrete with varying ratios from 0.25 to 1.00%. The evaluation of PSSNa as additive was based on results of fluidity and mechanical strength to compression. In mortars with water/cement ratio of 0.48, an increase in flow was observed when the dosage of PSSNa varied from 0.25 to 1.00%. The dispersion of mortar components was improved due to the adsorption of PSSNa on cement particles, which increased the mechanical strength of mortars. Similar results were obtained with the

  7. Análise fluido-dinâmica do escoamento em ensaio de permeabilidade ao ar de argamassas preparadas com cimento Portland de alto-forno Fluid-dynamic analysis of the flow in air permeability measurement of mortars prepared with blast-slag furnace Portland cement

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    V. M. Pereira

    2008-06-01

    Full Text Available O estudo dos fenômenos fluido-dinâmicos de escoamento em meios porosos tem sido de grande interesse por diversas áreas das ciências, de forma a se avaliar não só a permeabilidade do material, mas também analisar o comportamento do fluido permeante quando no interior destes materiais. Tratando-se de compósitos à base de cimento, a mensuração da permeabilidade torna-se fundamental para que sua durabilidade possa ser estimada, pois é a permeabilidade que controla a taxa de ingresso e movimentação de agentes deletérios no interior destes materiais. Dessa forma, diversas metodologias e equacionamentos matemáticos têm sido utilizados para prever a permeabilidade de materiais à base de cimento. No entanto, várias discrepâncias e disparidades nos resultados têm sido encontradas. Dentre as metodologias empregadas para mensurar a permeabilidade de meios porosos, encontra-se a desenvolvida por Thenoz, a qual tem demonstrado bons resultados em materiais à base de cimento. Dessa forma, este trabalho visa, por meio de ensaio de permeabilidade ao ar, realizado de acordo com a metodologia de Thenoz, avaliar o comportamento fluido-dinâmico do ar durante o ensaio de permeabilidade em argamassas. Para isto, foram utilizadas argamassas preparadas com dois tipos de cimento Portland (CP II E - 32 e CP III - 32, duas relações água/cimento (0,5 e 0,6 e ensaiadas em idades de 14 e 28 dias. Por meio dos resultados obtidos foi possível observar que durante o escoamento a compressibilidade do ar pode ser ignorada e o regime de escoamento pode ser considerado como laminar, demonstrando que a metodologia proposta por Thenoz e o equacionamento matemático empregado pode resultar em coeficientes de permeabilidade ao ar confiáveis, pois fenômenos e considerações que poderiam influenciar neste tipo de escoamento podem ser negligenciados.Fluid-dynamic phenomena study in porous media flow has been of great interest for diverse areas of sciences

  8. STUDY OF EXPANSIVE REACTIONS IN MORTAR MADE OF PORTLAND CEMENT WITH RICE HUSK ASH (RHA = ESTUDO DE REAÇÕES EXPANSIVAS EM ARGAMASSAS DE CIMENTO PORTLAND COM CINZA DE CASCA DE ARROZ (CCA

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    Jorge Luis Akasaki

    2007-01-01

    acaba sendo descartada de modo inadequado, gerando poluição no meio ambiente. No sentido de encontrar uma finalidade viável para a utilização de cinza de casca de arroz na construção civil, o presente trabalho estuda avariação do comportamento de argamassas com diferentes teores de CCA. (Cinza de Casca de Arroz. Trabalhou-se com corpos-de-prova prismáticos, com dimensões de 25x25x285mm, moldados com 0% (referência, 5%, 10% e 25% de CCA, em substituição em massa ao cimento. A influência da cinza foi constatada através dos seguintes ensaios: eficiência de materiais pozolânicos em evitar a expansão e reação álcali-agregado. O resultado obtido no ensaio de redução da expansão (NBR 12651 mostrou que a CCA reduz consideravelmente a expansão de argamassas devido à reação com o álcalis do cimento (94,29%, quando o limite mínimo de redução exigido pela norma para uma pozolana é de 75%. Embora no ensaio de reação álcaliagregado(ASTM C-1260 os valores de expansão tenham ficado acima do limitepermitido para considerar o material inócuo, tanto o teor de 5% quanto o de 10% de CCA obtiveram resultados melhores (expandiram menos que o traço de referência.

  9. Potencialidades da metacaolinita e do tijolo queimado moído como substitutos parciais do cimento Portland Potentialities of metakaolin and crushed waste calcined clay brick as partial replacement of Portland cement

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    João de Farias Filho

    2000-12-01

    Full Text Available Avalia-se, neste trabalho, a potencialidade do uso da metacaolinita e dos resíduos de produção de tijolos cerâmicos queimados finamente moídos, como substitutos parciais do cimento Portland. Os materiais foram caracterizados física, química e mineralogicamente, além de determinado o índice de atividade pozolânica com cimento Portland. A evolução da resistência a compressão e a flexão das argamassas foi avaliada até as idades de, respectivamente, 365 e 208 dias. As porcentagens de substituição do cimento Portland, em peso, pelos materiais pozolânicos, variaram de 20 a 50%, enquanto o fator água/cimento variou de 0,37 a 0,45. Os resultados obtidos indicaram que a metacaolinita e o tijolo moído queimado possuem elevada atividade pozolânica e que a resistência a compressão, aos 28 dias, das argamassas mistas, foi superior à das argamassas de cimento Portland para os níveis de substituição e fatores água/cimento estudados. Um modelo matemático para predição da resistência à compressão das argamassas mistas é proposto com base em um desenho fatorial de experimentos.This paper evaluates the potentiality of metakaolin and crushed waste fired clay brick as cement replacement materials. They were characterised physically, chemically and mineralogically and their activity with Portland cement determined. The influence of the partial replacement of Portland cement on the development of compressive and flexural strength was evaluated until the age of, respectively, 365 and 208 days. The percentage of cement replacement, in weight, ranged from 20 to 50%, whereas the water/cement ratio ranged from 0.37 to 0.45. The results obtained show that the metakaolin and crushed calcined clay brick presented a good pozolanic activity and that the compressive strength of the blended mortars after 28 days of cure was higher than that observed for the reference Portland cement for all levels of cement replacement and water/cement ratio. A

  10. The influence of energy mixing in pastes of Portland cement used in well cementing; Influencia da energia de mistura em pastas de cimento Portland utilizadas em cimentacao de pocos petroliferos

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    Lima, Flank M.; Oliveira, Valeska G.; Martinelli, Antonio E.; Melo, Dulce M.A.; Cachina, Gustavo H.A.B. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

    2004-07-01

    Portland cement is by far the most important binding material used in oil well cementing. Its mixture process in field is one of the most important problems in well cementing practices. The objective of that process is to prepare the cement slurry with similar properties those found in preliminaries laboratory tests. That objective should be found, or else, the relevance of the calculations and tests accomplished to determine the displacement flow, friction pressure, thickening time and the fluid loss rate of cement slurry. It was verified that the mixture time increases significantly the energy of mixture of the pastes, provoking changes in the plastic viscosity, yield point and forces gel of pastes. The hydration rates of slurries were affected for the mixture conditions, causing a decrease of about 40% in thickening time. Measures of fluid loss evidenced that for larger mixture times happened a reduction of the percentile of free water of 4,2% to 0,0%, provoked by the increase of the reaction of the system. (author)

  11. Efeito do tempo de cura na rigidez de argamassas produzidas com cimento Portland Effect of the curing time on the stiffness of mortars produced with Portland cement

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    G. C. R. Garcia

    2011-03-01

    Full Text Available O concreto de cimento Portland é um dos materiais mais usados no mundo inteiro, entretanto, devido a sua estrutura ser muito complexa, torna-se imprescindível estudar suas propriedades com bastante profundidade. O concreto é produzido a partir de uma argamassa, de areia e cimento, com adição de agregados graúdos, sendo que suas propriedades estão basicamente suportadas nessa argamassa de constituição. O objetivo deste trabalho foi estudar a variação da rigidez de duas argamassas de composições com razão cimento:areia de 1:2 e 1:3 em função do tempo de cura, tendo como parâmetro a variação do módulo de Young. Os resultados mostraram que o módulo de Young cresce até atingir o valor máximo no oitavo dia, sendo que nos três primeiros dias esse crescimento é mais acentuado. A análise dos resultados indica que grande parte do processo de hidratação do cimento, com formação das ligações químicas responsáveis pela rigidez da argamassa, acontece nos primeiros dias de cura.Concrete produced with Portland cement is one of building materials most widely used worldwide. However, due to its highly complex structure, its properties require in-depth studies. Concrete is a mortar consisting of a mixture of cement, sand and coarse aggregates, and its properties are represented basically by the mortar base. The aim of this work was to study the change in stiffness of two mortar compositions cured at 25 ºC with a cement-to-sand ratio of 1:2 and 1:3, as a function of curing time using the variation of Young modulus as the measuring parameter. The results showed that Young modulus increases up to a maximum value on the 8th day, and that this increase is more pronounced during the first three days. An analysis of the results indicates that a large part of the cement hydration process, involving the formation of chemical bonds that are responsible for the mortar stiffness, takes place in the early days of curing.

  12. Analysis by X-Ray images of EVA waste incorporated in Portland Cement; Analise atraves de imagens de raios X da incorporacao de residuo de EVA em cimento Portland

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    Marques, M.A.; Antunes, M.L.P.; Montagnoli, R.M.; Mancini, S.D., E-mail: marciomq@sorocaba.unesp.br [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Sorocaba, SP (Brazil)

    2012-07-01

    The EVA is a copolymer used by Brazilian shoes industries. This material is cut for the manufacture of insoles. This operation generates about 18% of waste. The EVA waste can be reused in incorporation in Portland cement to construction without structural purposes. The aim of this work is to show X-rays images to assessment the space distribution of the wastes in the cement and to evaluate the use of this methodology. Cylindrical specimens were produced according to ABNT - NBR 5738 standards. The volume relation of sand and cement was 3:1, 10% and 30% of waste was incorporated in cement specimens. X-Rays images were obtained of cylindrical specimens in front projection. The images showed that the distribution of the waste is homogeneous, consistent with what was intended in this type of incorporation, which can provide uniformity in test results of compressive strength. (author)

  13. Biofouling e biodeterioração química de argamassa de cimento portland em reservatório de usina hidroelétrica Biofouling and chemical biodeterioration in hydroeletric power plant portland cement mortar

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    Kleber Franke Portella

    2009-01-01

    Full Text Available Last decade Brazilian rivers experimented progressive biofouling of Limnoperna fortunei communities and Cordylophora caspia hydroids. The microhabitat is so favorable that in around 1.5 years L. fortunei increased from 0.39 to nearby 149,000 units/m². Ten Portland cement mortar samples were produced with 1: 3.5: 0.4 dosages and installed for 1 year at Salto Caxias Brazilian Power Plant reservoir in 0.5 m and 1.0 m deep to investigate the biofouling influence on hydraulic civil structures. SEM, EDS, visual investigation and XRF results indicate none direct chemical interrelationships between L. fortunei and the mortar samples. However C. caspia diminished the mortar surface resistance and caused cement paste leaching.

  14. Reforço em compósito de cimento portland através da adição nanotubos de carbono de paredes múltiplas

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    Rogerio Daltro Knuth

    2016-07-01

    Full Text Available A pesquisa desenvolvida no presente trabalho esta embasada na aplicação da nanotecnologia a novos compósitos cimentícios, visando à melhoria das propriedades das argamassas. O objetivo do trabalho foi o de analisar o desempenho físico e mecânico e a ancoragem de uma argamassa de revestimento produzida com nanotubos de carbono de paredes múltiplas (NTCPM, adicionados na quantidade de 0,30% em relação à massa de cimento do compósito, comparativamente ao desempenho com uma argamassa industrializada. Para o presente estudo foi necessário funcionalizar e dispersar os NTCPM, utilizando-se os ácidos sulfúrico (H2SO4 e nítrico (HNO3, e a dispersão foi por ultrassom. Os NTCPM funcionalizados foram neutralizados com hidróxido de amônio (NH3. Foram realizados ensaios de caracterização física e mecânica no estado fresco e no estado endurecido nas argamassas de revestimento com NTCPM e industrializada e análise microestrutura. Os resultados obtidos indicam que a argamassa com NTCPM apresenta melhor desempenho que a argamassa industrializada, no tocante a densidade, consistência, viscosidade, resistência à tração e resistência a compressão axial. Palavras-chave: Argamassas de revestimento. Nanotubos de carbono. Compósitos. Propriedades físicas e mecânicas. Microestrutura.

  15. Análise físico-química do MTA e do cimento Portland associado a quatro diferentes radiopacificadores

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    Bernardo Cesar COSTA

    Full Text Available INTRODUÇÃO: O Mineral Trióxido Agregado (MTA é composto por cimento Portland (CP e um radiopacificador (óxido de bismuto.OBJETIVO: Avaliar tempo de presa, solubilidade, pH, liberação de íons Cálcio e radiopacidade do cimento Portland puro ou associado a quatro radiopacificadores (sulfato de bário, carbonato de bismuto, óxido de bismuto e iodofórmio, comparados ao MTA branco (Angelus, Londrina, Brasil.MATERIAL E MÉTODO: A proporção empregada CP/radiopacificador foi de 4:1 em peso, (80% de cimento Portland e 20% de radiopacificador. A especificação 57 da ADA foi usada para avaliação do tempo de presa. A solubilidade foi analisada segundo a especificação ISO 6876/2001. A avaliação do pH foi realizada com peagâmetro digital e a liberação de íons Ca++foi verificada por meio de espectrofotômetro de absorção atômica. A radiopacidade foi determinada em milímetros de alumínio (mm/Al. Os resultados foram submetidos aos testes de Análise de Variância e Tukey, nível de significância 5%.RESULTADO: O sulfato de bário não alterou o tempo de presa final do CP. Radiopacidade inferior ao mínimo recomendado pelas normas da ADA nº 57 e ISO 6876/2001 foi observada para CP e CP associado com sulfato de bário. O CP associado ao iodofórmio apresentou solubilidade acima dos 3% recomendados pela ISO 6876/2001. Todos os materiais proporcionaram alcalinização do meio e promoveram liberação de íons cálcio.CONCLUSÃO: Carbonato de bismuto ou óxido de bismuto proporcionaram tempo de presa inicial, solubilidade, pH, liberação de íons Cálcio e radiopacidade adequados quando associados ao CP.

  16. Produção de painéis de cimento Portland reforçados com fibra de curauá (Ananas erectifolius)

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    Bilcati, Géssica Katalyne

    2015-01-01

    O presente trabalho trata do estudo referente ao desempenho da fibra vegetal amazônica curauá (Ananas erectifolius) aplicada no processo de produção dos painéis de cimento portland, analisando a compatibilidade, os tratamentos realizados nas fibras de curauá, visando à melhoria das propriedades físicas e mecânicas dos painéis. A metodologia deste trabalho foi desenvolvida a partir da produção dos painéis cimento portland reforçados com fibras de curauá, variando os teores e os tipos de tratam...

  17. Potencial da cinza do bagaço da cana-de-açúcar como material de substituição parcial de cimento Portland Potential of sugarcane bagasse ash as a partial replacement material for Portland cement

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    Marcos O. de Paula

    2009-06-01

    Full Text Available Este trabalho, voltado para a avaliação do potencial da cinza do bagaço da cana-de-açúcar (CBC como material de substituição parcial do cimento Portland em argamassa, objetivou apresentar opção viável para a destinação deste resíduo, cuja quantidade gerada aumentará significativamente nos próximos anos, em decorrência da ampliação do setor de produção de álcool combustível; além disso, o emprego da CBC como adição mineral, substituindo parte do cimento em argamassas e concretos, contribui para a redução do impacto ambiental desses materiais, em boa parte decorrente da produção do cimento. O procedimento experimental abordou não só caracterização da CBC mas também a avaliação, através de ensaios físicos e mecânicos, em que os resultados mostraram que o bagaço apresenta rendimento de CBC de 10%, com a cinza sendo composta de 84% de SiO2 e 5% de Carbono. A sílica na CBC apresenta-se na fase amorfa e nas fases cristalinas de cristobalita e quartzo. Os índices de atividade pozolânica comprovam a reatividade da CBC. Do ponto de vista da resistência à compressão, argamassas com teores de CBC entre 0 e 30% indicaram a possibilidade de substituição de até 20% do cimento pela CBC.This study is focused on the evaluation of the effects of the partial replacement of Portland cement by sugarcane bagasse ash (CBC in mortars. The main objective was to find a suitable destination for an agricultural residue generated in an increasing amount in Brazil, as a result of the boom of the use of ethanol as an alternative fuel to gasoline. Also, the use of CBC as a mineral admixture in mortars and concretes contributes to a decrease in the environmental impact of these materials related to cement production. Experimental techniques were applied both for the CBC characterization and for the evaluation of its use as a mineral admixture in mortars, based on mechanical and physical tests. The yield of CBC from sugarcane

  18. Microscopic analysis of dog dental pulp after pulpotomy and pulp protection with mineral trioxide aggregate and white Portland cement Análise microscópica da polpa dental de cães após pulpotomia e proteção pulpar com agregado de trióxido mineral e cimento Portland branco

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    Renato Menezes

    2004-06-01

    Full Text Available Considering previous studies on the similarity between the chemical composition of the mineral trioxide aggregate and the Portland cement, the purpose of this study was to investigate the pulp response of dog's teeth after pulpotomy and direct pulp protection with MTA Angelus and white Portland cement. Thirty eight pulp remnants were protected with these materials. One hundred and twenty days after treatment, the animals were sacrificed and the specimens removed and prepared for histological analysis. Both materials demonstrated the same results when used as pulp capping materials, inducing hard tissue bridge formation and maintaining pulp vitality in all specimens. The MTA Angelus and the white Portland cement showed to be effective as pulp protection materials following pulpotomy.Considerando estudos anteriores sobre a similaridade entre a composição química do agregado de trióxido mineral e o cimento Portland, o objetivo deste estudo foi investigar a resposta pulpar de dentes de cães após pulpotomia e proteção pulpar direta com MTA Angelus e cimento Portland branco. Trinta e oito remanescentes pulpares foram recobertos com esses materiais. Cento e vinte dias após o tratamento, os animais foram sacrificados e os espécimes removidos e preparados para análise histológica. Ambos os materiais demonstraram os mesmos resultados quando utilizados como materiais de capeamento pulpar, induzindo a formação de ponte de tecido mineralizado e mantendo a vitalidade pulpar em todos os espécimes. Ambos matérias se mostraram efetivos como protetores pulpares após pulpotomia em dentes de cães.

  19. Atividade antimicrobiana do metronidazol gel associado ao hidróxido de cálcio e ao cimento Portland frente às bactérias anaeróbias relacionadas a reações periapicais do tipo crônica = The antibacterial activity of the metronidazole gel associated with calcium hydroxide and cement portland front the anaerobic bacterias related to cronic periapical lesions

    Directory of Open Access Journals (Sweden)

    Mendonça, Eduarda Rodrigues da Silva

    2007-01-01

    Full Text Available As pesquisas com o intuito de descobrir novas substâncias com finalidade para medicação intracanal é uma realidade. Tem como objetivos principais a melhoria das propriedades dos medicamentos utilizados usualmente, tais como o hidróxido de cálcio para com isso suprir algumas deficiêcias que possam existir. Este trabalho teve como propósito a análise in vitro da ação do metronidazol gel em associação ao hidróxido de cálcio e cimento Portland, como medicação intracanal. Os testes foram realizados em bactérias anaeróbias facultativas, as quais compõe a flora de dentes portadores de reação periapical crônica. O hidróxido de cálcio é, ainda, a medicação intracanal mais utilizada, visto que, possui efeito antibacteriano pronunciado contra a maioria dos microrganismos existentes no interior de canais radiculares infectados. O metronidazol veio a ser testado por possuir capacidade bactericida atuante, principalmente, em bactérias anaeróbias estritas. Podendo atuar nos microrganismos que são resistentes à ação do hidróxido de cálcio. Entretanto, ao término deste experimento, o metronidazol gel quando testado, comparado e associado ao hidróxido de cálcio e cimento Portland não teve resposta superior a ação do hidróxido de cálcio puro como medicação intracanal, tendo o cimento Portland apenas melhorado as propriedades físico/química dessa pasta

  20. Cimento de ionômero de vidro : uso atual e perspectivas em odontologia restauradora

    OpenAIRE

    Jardim, Patrícia dos Santos; D'Agostini, Fabiane Lobato; Masotti, Alexandre Severo

    2007-01-01

    Os cimentos de ionômero de vidro apresentaram uma diminuição em seu uso clínico como conseqüência de sua limitação estética e mecânica em relação às resinas compostas. Porém, devido à intensa discussão sobre a efetiva biocompatibilidade e resistência de união a longo prazo dos sistemas adesivos, tem-se intensificado novamente o interesse pelos cimentos ionoméricos. Em relação à resistência de união, apesar dos valores imediatos apresentados pelos sistemas adesivos serem mais elevados que os d...

  1. Avaliação preliminar do emprego de arenito zeolítico da região nordeste do Brasil como material pozolânico para cimento Portland Preliminary evaluation of sandstones from northeastern Brazil with pozzolanic properties for Portland cement

    Directory of Open Access Journals (Sweden)

    M. S. Picanço

    2011-12-01

    Full Text Available As zeolitas possuem atividade pozolânica normalmente sem a necessidade de ativação térmica, por isto têm sido empregadas na produção de cimento e concreto hidráulicos desde a época do império romano. Hoje em dia são utilizadas na fabricação do cimento Portland através da substituição do clinquer em percentuais que variam entre 5 e 20%, dependendo da reatividade e da finura da zeólita. Em razão disto, são muito importantes do ponto de vista econômico e ambiental, principalmente quando não necessitam de tratamento térmico para adquirirem caráter pozolânico satisfatório, porque reduzem significativamente a energia de produção do clinquer e a liberação de CO2 proveniente tanto da descarbonatação da calcita como da combustão de combustíveis fósseis. Contudo, dados sobre reservas de zeólitas naturais são escassos e imprecisos. No Brasil, não existe conhecimento sobre depósitos naturais de zeólitas que possam ser explorados comercialmente. No nordeste do Brasil existe a ocorrência de zeolitas sedimentares relacionadas a arenitos descoberta nos anos 2000. Estes arenitos são constituídos de quartzo, argilominerais e zeolitas naturais (estilbita. O objetivo geral desse trabalho foi avaliar se esta zeólita natural presente no arenito possui atividade pozolânica satisfatória para ser empregada como adição mineral em cimentos Portland. No programa experimental o arenito zeolítico passou por beneficiamento através da remoção, por peneiramento, do quartzo e outros minerais inertes, de modo a concentrar a zeólita estilbita e com isto verificar as propriedades pozolânicas deste mineral. No estudo experimental foram empregadas as técnicas de difração de raios X, calorimetria, ensaios químicos e de determinação da atividade pozolânica em argamassas de cal hidratada e cimento Portland. Os resultados mostraram que o arenito zeolítico acelerou a hidratação do cimento Portland devido a extrema finura do

  2. Ensaios de arrancamento e de empuxamento aplicados a taliscas de bambu encravadas em corpos-de-prova de solo-cimento

    OpenAIRE

    Wilza G. R. Lopes; Wesley J. Freire; Gisleiva C. dos S. Ferreira

    2002-01-01

    Neste trabalho, taliscas de bambu da espécie Dendrocalamus giganteus, engastadas em corpos-de-prova de solo-cimento, foram submetidas a ensaios de arrancamento (pull-out) e de empuxamento (push-out) a fim de se determinar sua resistência de aderência. Para esta finalidade, foi utilizado um solo-cimento feito a partir de um solo arenoso que continha aproximadamente 70% de areia. Corpos-de-prova de solo-cimento, de 15 cm de diâmetro e 30 cm de altura, foram moldados com 14% de cimento na umidad...

  3. Development of the Portland cement slurries with diatomaceous earth to the oil industry; Desenvolvimento de pastas de cimento Portland com adicao de diatomita para a industria do petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Brito, Roseane A; Melo, Dulce M.A.; Martinelli, Antonio E.; Simao, Cristina A.; Paiva, Maria D.M. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil); Melo, Marcus A.F. [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES)

    2004-07-01

    The class-G Portland cement has been used with success in oil well cementing. The material is usually shipped to the Northeast Brazil, because the only plant that manufactures class-G is located in Cantagalo/RJ. The present work investigates the influence of the partial substitution of Portland cement by diatomaceous earth, aiming at reducing the costs in oil well cementing, improving the slurry properties and using local raw material. The diatomaceous earth has pozzolanic properties and can be used as extenders of cement slurries. This properties added to the lower cost and availability of this material in Northeast Brazil, make the diatomaceous earth a candidate material to produce light cements, to well conditions in advanced phases of production. It were evaluated the rheological properties of the slurries (at 25 and 52 deg C), volume of free water, compressive strength after curing for 8, 24 and 48 h at 38 deg C, and consistometry tests. The results show that the diatomaceous earth maintain the viscosity values and gel force suitable for use in oil well cementing. No free water was observed in the formulations. It was also verified that the compressive strength of slurries hardened with diatomaceous earth is similar to those with only Portland cement and that the minimum compressive strength of 300 psi, after curing for 8 h was reached. The thickening time was longer than the average value and the application value. (author)

  4. Advances in glass-ionomer cements Avanços em cimentos de ionômero de vidro

    Directory of Open Access Journals (Sweden)

    Carel Leon Davidson

    2006-01-01

    Full Text Available This article describes the properties, advances and shortcomings of glass-ionomer cement as a restorative material. The adhesion of glass-ionomer to tooth structure is less technique sensitive than composite resins and its quality increases with time. Therefore glass-ionomer might turn out to the more reliable restorative material in minimal invasive dentistry based on adhesive techniques.Este artigo descreve as propriedades, avanços tecnológicos e limitações dos cimentos de ionômero de vidro como material restaurador. A adesão dos cimentos ionoméricos à estrutura dental é menos sensível às variações técnicas do que o mecanismo de adesão das resinas compostas e a qualidade do cimento se aprimora com o uso clínico. Portanto o cimento de ionômero de vidro torna-se o material restaurador mais confiável em procedimentos restauradores minimamente invasivos baseados em técnicas adesivas.

  5. Propriedades mecânicas de materiais compósitos à base de cimento Portland e resina epoxi Mechanical properties of composite materials based on portland cement and epoxy resin

    Directory of Open Access Journals (Sweden)

    T. H. Panzera

    2010-03-01

    Full Text Available O estudo de materiais de alto desempenho e multifuncionais, como os compósitos poliméricos cimentícios, tem sido o foco de inúmeras pesquisas na indústria da construção civil. Este trabalho investiga o efeito da combinação de uma fase polimérica termorrígida, uma resina epóxi, com cimento Portland branco estrutural, seguido da avaliação da resistência à compressão e módulo de elasticidade. Este compósito, quando comparado individualmente com as suas matérias-prima originais, promove um aumento da resistência mecânica à compressão, redução da massa específica e, também uma mudança significativa do comportamento mecânico. As mudanças nas propriedades mecânicas estão associadas à hidratação da fase cimentícia na presença da resina, fato comprovado através da análise espectroscópica na região do infravermelho.The study of multi-functional materials of high performance, as the polymeric-cementitious composites, has been the focus of several researches in the industry of the civil engineering. This work investigates the effect of the combination of a thermorigid epoxy phase and the white Portland cement, followed by the evaluation of its compressive strength and modulus of elasticity. This composite, when the phases are individually compared, provides an increase of the compressive strength, a reduction of the density, and a significant change of the mechanical behaviour. The changes in mechanical behaviour are associated with the hydration of cement in the presence of resin, which was evident after infrared spectroscopy analysis.

  6. Evaluation of the use of red mud as a pozzolanic additive in Portland cement; Avaliacao do uso de residuo de bauxita como aditivo pozolanico no cimento Portland

    Energy Technology Data Exchange (ETDEWEB)

    Fortes, Gustavo Mattos; Balbino, Thiago Gabriel Ferreira; Lourenco, Rafaela Roberta; Rodrigues, Jose de Anchieta [Universidade Federal de Sao Carlos (GEMM/DEMa/UFSCar), Sao Carlos, SP (Brazil). Departamento de Engenharia de Materias. Grupo de Engenharia de Microestrutura de Materiais; Montini, Marcelo [Alcoa Aluminio S.A., Pocos de Caldas, MG (Brazil)

    2011-07-01

    It is estimated that the aluminum industry generates approximately 13.7 million tones/year of red mud (RB) in Brazil. Although, being the RB rich in Al{sub 2}O{sub 3} and SiO{sub 2} and partially amorphous, a potential pozzolanic activity is suggested. Thus, this work aims to evaluate the application of 15w-% of RB, as a pozzolanic additive, to the ordinary Portland cement (CPI), simulating a pozzolanic compost Portland cement (CPII-Z). To study the pozzolanic activation of the RB, this one was added without calcination, calcinated at 400°C and at 600°C. The compressive strength was measured in mortars of CPI with additions of RB, of CPI and CPII (references), after 28 days of curing. The analysis of the apparent porosity and the characterization of the hydration products were done to complement the evaluation. The mortars with calcinated RB showed good results of mechanical strength, reaching more than 85% (45 MPa) of the CPI's strength and higher values than the CPII-Z32. (author)

  7. Cimentos de escória ativada com silicatos de sódio.

    OpenAIRE

    Vanderley Moacyr John

    1995-01-01

    Os cimentos de escória apresentam boas possibilidades de mercado, especialmente em aplicações em que o cimento Portland não possa ser utilizado ou onde o seu uso provoque uma elevação dos custos. A confecção de matrizes para fibras sensíveis aos álcalis e a produção de cimentos com baixo calor de hidratação são exemplos. Neste trabalho, a escória foi ativada com silicato de sódio e cal hidratada. O ativador foi formulado de maneira a proporcionar teores de Na2O de 2,5% e 5%, SiO2 de 0% a 14,8...

  8. Swine deep bedding ashes as a mineral additive for cement based mortar Cinzas de cama sobreposta de suínos como adição mineral em argamassas de cimento

    Directory of Open Access Journals (Sweden)

    Melissa Selaysim Di Campos

    2008-04-01

    Full Text Available The sustainability of intensive swine production demands alternative destinations for the generated residues. Ashes from swine rice husk-based deep bedding were tested as a mineral addition for cement mortars. The ashes were obtained at 400 to 600ºC, ground and sieved through a 325 mesh sieve (# 0.045 mm. The characterization of the ashes included the determination of the index of pozzolanic activity with lime. The ashes were also tested as partial substitutes of Portland cement. The mortars were prepared using a cement:sand proportion of 1:1.5, and with water/cement ratio of 0.4. Three percentages of mass substitution of the cement were tested: 10, 20 and 30%. Mortar performances were assessed at 7 and 28 days determining their compressive strength. The chosen condition for calcinations at the laboratory scale was related to the maximum temperature of 600ºC since the resulting ashes contained vitreous materials and presented satisfactory values for the pozzolanic index under analysis. The pozzolanic activity indicated promising results for ashes produced at 600ºC as a replacement of up to 30% in cement masses.A sustentabilidade das regiões de produção intensiva de suínos requer destinos alternativos para os resíduos gerados. Cinzas de cama sobreposta de suínos à base casca de arroz, foram testadas como adição mineral em substituição ao cimento. As cinzas foram obtidas nas temperaturas de 400 a 600ºC, moídas e passadas por peneira ABNT 325 (# 0,045 mm. A caracterização de cinzas incluiu a determinação do índice de atividade pozolânica com a cal. As cinzas também foram testadas como substitutos parciais de cimento Portland. As argamassas foram preparadas na proporção cimento:areia de 1:1,5 e com fator água-cimento de 0,4. Três porcentagens de substituição do cimento comercial foram usadas: 10, 20 e 30% em massa. O desempenho das argamassas foi avaliado aos 7 e aos 28 dias com a determinação da resistência

  9. Influence of the waste glass in the axial compressive strength of Portland cement concrete; Influencia dos residuos vitreos na resistencia a compressao axial do concreto de cimento Portland

    Energy Technology Data Exchange (ETDEWEB)

    Miranda Junior, E.J.P.; Paiva, A.E.M., E-mail: edson.jansen@hotmail.com [Instituto Federal de Educacao, Ciencia e Tecnologia do Maranhao (PPGEM/IFMA), Sao Luis, MA (Brazil). Programa de Pos-Graduacao em Engenharia de Materiais

    2012-07-01

    In this work, was studied the influence of the incorporation of waste glass, coming from the stage of thinning and polishing of a company of thermal glass treatments, in the axial compressive strength of Portland cement concrete. The coarse and ground aggregates used was crushed stone and sand, respectively. For production of the concrete, percentages of glass residues of 5%, 10% and 20% had been used in substitution to the sand, and relations water/cement (a/c) 0,50, 0,55 and 0,58. The cure of the test bodies was carried through in 7, 14 and 28 days. The statistics analysis of the results was carried out through of the analysis of variance for each one of the cure times. From the results of the compressive strength of the concrete, it could be observed that the concrete has structural application for the relation a/c 0,5, independently of waste glass percentage used, and for the relation a/c 0,55 with 20% of waste glass. (author)

  10. Caracterização de misturas de rejeitos de minério de ferro melhoradas com adição de cimento com vistas à aplicação em estradas e aterros

    OpenAIRE

    Oliveira,Tales Moreira de

    2013-01-01

    Neste trabalho, foi realizada uma campanha de ensaios de caracterização das propriedades físico-mecânicas e hidráulicas de misturas de rejeitos provenientes do beneficiamento de minério de ferro, com e sem adição de cimento Portland composto com escória, tipo CP II-E-32, visando à aplicação em camadas de pavimentos rodoviários e à construção de aterros. As amostras de rejeito foram obtidas de pontos específicos dos processos de beneficiamento do minério de ferro pelos processos de flotação e ...

  11. Avaliação da influência do tipo de cimento na expansibilidade das misturas de fosfogesso e cimento

    Directory of Open Access Journals (Sweden)

    Andréa Regina Kaneko Kobayashi

    2009-12-01

    Full Text Available

    Fosfogesso é um resíduo sólido da produção de ácido fosfórico pelas indústrias de fertilizantes. Geram-se cerca de 180 milhões de toneladas deste resíduo por ano no mundo, causando problemas com a sua armazenagem. Este trabalho apresenta um resumo dos resultados de ensaios laboratoriais para avaliar a influência do tipo de cimento Portland na expansibilidade das misturas de fosfogesso e cimento para uso como material de construção de bases e sub-bases de pavimentos. A expansão foi medida em corpos de prova, compostos com diferentes proporções de fosfogesso e cimento, variando-se o tipo de cimento, a energia de compactação e o período de cura. Para todas as misturas investigadas, considerando-se o período de 84 dias de cura, a maior parte da expansão ocorreu nos primeiros 28 dias. Concluiu-se que a influência do tipo de cimento é significante na expansão destas misturas.

  12. Estudo "in vitro" da infiltração marginal em restaurações de cavidades classe I, com composito e base de cimento de ionomero de vidro

    OpenAIRE

    Rosangela Marques Duarte

    1992-01-01

    Resumo: A infiltração marginal em restaurações de cavidades classe I com compósito e base de cimento de ionômero de vidro foi observada neste estudo "in vitro". Cavidades classe I em 21 dentes humanos do grupo dos pré-molares foram preparadas. Os dentes foram divididos em 3 grupos, sendo que as cavidades foram assim tratadas: No grupo A foram forradas com base de cimento de ionômero de vidro e restauradas com resina fluida e compósito. No grupo B foram forradas com base de cimento de ionôm...

  13. Desempenho de telhas de escória de alto forno e fibras vegetais em protótipos de galpões

    OpenAIRE

    Conceição,Maristela N. da; Alves,Sulivan P.; Telatin Júnior,Aurélio; Silva,Iran J. O. da; PIEDADE, Sônia M. S.; Savastano Júnior,Holmer; Tonoli,Gustavo

    2008-01-01

    Busca-se, em todo o mundo, a substituição do cimento amianto por alternativas seguras para o ambiente e para a saúde do trabalhador, além de econômicas, razão por que o uso de fibras vegetais como aglomerado em países tropicais onde estes resíduos são abundantes, tem-se mostrado bastante viável. No presente experimento foram comparadas telhas de cimento amianto pintadas com tinta reflexiva, telhas cerâmicas e telhas compostas de uma matriz à base de cimento Portland CPII 32Z (ABNT NBR-5735), ...

  14. Effects of chemical and mineral additives and the water/cement ratio on the thermal resistance of Portland cement concrete; O efeito de aditivos quimicos e minerais e da relacao agua/cimento na resistencia ao calor do concreto de concreto de cimento Portland

    Energy Technology Data Exchange (ETDEWEB)

    Cesar, Leandro Cesar Dias; Morelli, Arnaldo C.; Baldo, Joao Baptista [Sao Carlos Univ., SP (Brazil). Dept. de Engenharia de Materiais

    1998-07-01

    The exposure of Portland concrete to high temperatures (>250 deg C) can damage drastically the microstructural integrity of the material. Since the water/cement ratio as well as the inclusion of superplasticizers and mineral additives (silica fume) can alter constitutively and micro structurally the material, in this work it was investigated per effect of these additions on the damage resistance of portland concrete after exposure to high temperatures. (author)

  15. Resistance to acid attack of portland cement mortars produced with red mud as a pozzolanic additive; Resistencia ao ataque acido de argamassas de cimento Portland produzido com residuo de bauxita como aditivo pozolanico

    Energy Technology Data Exchange (ETDEWEB)

    Balbino, Thiago Gabriel Ferreira; Fortes, Gustavo Mattos; Lourenco, Rafaela Roberta; Rodrigues, Jose de Anchieta [Universidade Federal de Sao Carlos (DEMa/PPGCEM/UFSCar), SP (Brazil). Programa de Pos-Graducao em Ciencia e Engenharia de Materiais. Departamento de Engenharia de Materiais; Montini, Marcelo [Alcoa Aluminio S.A., Pocos de Caldas, MG (Brazil)

    2011-07-01

    Portland cement structures are usually exposed to aggressive environments, which requires the knowledge of the performance of these materials under deleterious conditions. In this study, it was evaluated the resistance to acid attack of mortars that contain ordinary (CPI) and compost (CPII-Z) Portland cements, adding to the first red mud (RB) as a pozzolanic additive in different conditions: without calcination, calcined at 400 ° C and at 600 ° C. The specimens were subjected to HCl and H{sub 2}SO{sub 4} solutions, both with concentration of 1.0 Mol L{sup -1} for 28 days, monitoring the weight loss and leached material nature by atomic emission inductively coupled plasma (ICP). The hydration products were studied by thermogravimetric analysis (TGA) and X-ray diffraction (XRD) of the hydrated cement pastes. It was observed a reduction of portlandite amount in the RB containing cement pastes, indicating a possible pozzolanic activity of the red mud. The mortars prepared with RB were more resistant to HCl, while that ones with calcined RB present a better performance in H{sub 2}SO{sub 4} attack. (author)

  16. Avaliação do desenvolvimento in vitro de carie secundaria em esmalte e dentina radicular adjacentes a restauração metalica cimentada : comparação entre cimento de ionometro de vidro modificado por resina e cimento de fosfato de zinco

    OpenAIRE

    1999-01-01

    Resumo: A cárie secundária é apontada como a principal causa de fracasso de restaurações fixas indiretas. Materiais que liberam flúor têm sido recomendados para pacientes com alto risco à cárie, mas não há evidências conclusivas sobre seu efeito em próteses fixas. Este trabalho avaliou a influência do cimento de ionômero de vidro modificado por resina no desenvolvimento in vitro de cárie em esmalte e dentina radicular adjacentes a restauração metálica cimentada, em comparação com o cimento de...

  17. Evaluation of Portland cement from X-ray diffraction associated with cluster analysis; Avaliacao de cimento Portland a partir da difracao de raios X associada a analise por agrupamento

    Energy Technology Data Exchange (ETDEWEB)

    Gobbo, Luciano de Andrade, E-mail: luciano.gobbo@panalytical.com [Panalytical Brasil, Sao Paulo, SP (Brazil); Montanheiro, Tarcisio Jose, E-mail: tarcisio.montanheiro@gmail.com [Instituto Geologico, Secretaria de Estado do Meio Ambiente, Sao Paulo, SP (Brazil); Montanheiro, Filipe, E-mail: flpmontanheiro@gmail.com [Universidade Estadual Paulista (LEBAC/UNESP), Rio Claro, SP (Brazil). Departamento de Geologia Aplicada. Lab. de Estudos de Bacias; Sant' Agostino, Lilia Mascarenhas, E-mail: agostino@usp.br [Universidade de Sao Paulo (USP), SP (Brazil). Instituto de Geociencias. Departamento de Geologia Sedimentar e Ambiental

    2013-12-15

    The Brazilian cement industry produced 64 million tons of cement in 2012, with noteworthy contribution of CP-II (slag), CP-III (blast furnace) and CP-IV (pozzolanic) cements. The industrial pole comprises about 80 factories that utilize raw materials of different origins and chemical compositions that require enhanced analytical technologies to optimize production in order to gain space in the growing consumer market in Brazil. This paper assesses the sensitivity of mineralogical analysis by X-ray diffraction associated with cluster analysis to distinguish different kinds of cements with different additions. This technique can be applied, for example, in the prospection of different types of limestone (calcitic, dolomitic and siliceous) as well as in the qualification of different clinkers. The cluster analysis does not require any specific knowledge of the mineralogical composition of the diffractograms to be clustered; rather, it is based on their similarity. The materials tested for addition have different origins: fly ashes from different power stations from South Brazil and slag from different steel plants in the Southeast. Cement with different additions of limestone and white Portland cement were also used. The Rietveld method of qualitative and quantitative analysis was used for measuring the results generated by the cluster analysis technique. (author)

  18. A influência de fósforo, enxofre e estrôncio na mineralogia do clínquer portland

    OpenAIRE

    Marcelo Pecchio

    2013-01-01

    Em função de aspectos de sustentabilidade, a indústria de cimento tem utilizado, cada vez mais, combustíveis e matérias -primas não convencionais, que têm apor tado ao clínquer portland uma maior variabilidade de elementos químicos. O presente estudo tem por objetivo analisar o efeito de elementos menores selecionados (S, P e Sr) sobre a mineralogia do clínquer portland. Esses elementos passaram a fazer parte da composição de clínqueres industriais de modo mais expressivo na última décad...

  19. Advances in glass-ionomer cements Avanços em cimentos de ionômero de vidro

    OpenAIRE

    Carel Leon Davidson

    2006-01-01

    This article describes the properties, advances and shortcomings of glass-ionomer cement as a restorative material. The adhesion of glass-ionomer to tooth structure is less technique sensitive than composite resins and its quality increases with time. Therefore glass-ionomer might turn out to the more reliable restorative material in minimal invasive dentistry based on adhesive techniques.Este artigo descreve as propriedades, avanços tecnológicos e limitações dos cimentos de ionômero de vidro...

  20. Avaliação in vitro da microinfiltração em cavidades de classe V restauradas com diferentes combinações de resina composta e cimento de ionômero de vidro

    Directory of Open Access Journals (Sweden)

    ZANATA Régia Luzia

    1998-01-01

    Full Text Available O propósito deste estudo foi comparar o padrão de microinfiltração em restaurações classe V usando diferentes combinações de cimento ionomérico/resina composta. Cinqüenta cavidades foram preparadas nas superfícies vestibular e lingual de caninos e de pré-molares recém-extraídos. A margem gengival dos preparos estendeu-se até a dentina/cemento, e a margem oclusal localizou-se em esmalte. As cavidades foram restauradas como se segue: cimentos ionoméricos restauradores modificados por componentes resinosos (Fuji II LC e Vitremer; sistema adesivo/resina composta (Scotchbond Multi-Uso/Silux Plus; técnica sanduíche empregando-se o sistema adesivo/resina composta descrito, com um cimento ionomérico forrador (Vitrebond e GC Lining LC. Os espécimes foram armazenados em água destilada, polidos, submetidos à ciclagem térmica e imersos em fucsina. A extensão de penetração do corante foi classificada segundo o critério de escores, e os dados foram analisados estatisticamente, não sendo observadas diferenças significativas tanto entre materiais como entre margens.

  1. Caracterização física e mecânica de argamassas à base de cimento Portland e cinza de casca de arroz residual Physical and mechanical characterization on Portland cement mortar with rice husk ash addition

    Directory of Open Access Journals (Sweden)

    Michelle S Rodrigues

    2010-04-01

    Full Text Available A casca de arroz, utilizada como fonte de energia em indústrias de beneficiamento de arroz, converte-se, depois da queima, em uma cinza residual. Esse resíduo, ainda sem um destino adequado, é muitas vezes depositado em grandes áreas abertas e provoca elevado impacto ambiental. Este trabalho teve como objetivo avaliar a viabilidade de utilização da cinza de casca de arroz (CCA residual na produção de argamassas, como substituta parcial do cimento. A caracterização da CCA foi realizada por meio da análise de fluorescência de raios-X (composição química, análise do teor de carbono e difração de raios-X; também foi realizada análise granulométrica a laser. Os corpos de prova foram submetidos a dois tipos de exposição: ambientes externo e interno, com duração máxima de cinco meses. Foram realizados os ensaios de resistência à compressão simples e não destrutivo (velocidade do pulso ultrassônico - VPU. Embora as argamassas tenham apresentado bom desempenho mecânico, os ensaios de pozolanicidade indicaram que a cinza de casca de arroz residual utilizada não é uma pozolana, mas pode ser utilizada em matrizes cimentícias como material inerte (filler.Rice husk, employed as an energy source at milling industries in Brazil generates, after burning, a dark ash. This residue is not yet conveniently disposed, being currently dumped on large areas, causing environmental problems. This research intended to evaluate the applications of residual rice husk ashes (RHA as a partial replacement of cement for mortar production. Rice husk ash was chemically characterized through X-ray fluorescence, determination of carbon content, X-ray diffraction, and laser granulometric analysis. Mortar specimens were submitted to two different exposure conditions: internal and external environments at a maximum period of five months. Physical-mechanical testing were compressive strength and ultrasonic pulse velocity (UPV. Although presenting good

  2. Efeito da solução de clorexidina a 2% a um cimento ionomérico e um resinoso na adesão de pinos de fibra de vidro em raízes bovinas após 7 dias e 6 meses de armazenamento

    OpenAIRE

    Diana Ferreira Gadêlha de Araújo

    2013-01-01

    Este trabalho avaliou a influência do uso de solução de clorexidina a 2% (CHX) na resistência de união de pino de fibra de vidro à dentina radicular, utilizando um agente cimentante ionomérico modificado por resina e um cimento resinoso dual com sistema adesivo convencional, nos terços cervical, médio e apical. Oitenta raízes bovinas foram selecionadas, cortadas em 17mm e tratadas endodonticamente para em seguida serem divididas em 8 grupos: ARC (RelyX ARC/ScothBond MultiPurpose- cimento resi...

  3. Avaliação da liberação de flúor e da capacidade de recarga em diferentes cimentos de ionômero de vidro

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    Yasmine Mendes Pupo

    Full Text Available Objetivo Avaliar a liberação e a capacidade de recarga de flúor de diferentes cimentos de ionômero de vidro, durante a simulação de desafio cariogênico. Material e método Foram confeccionados 12 corpos de prova para cada grupo experimental, com cimentos de ionômero de vidro convencionais – Maxxion R (FGM, Ketac Molar EasyMix (3M ESPE; cimento de ionômero de vidro modificado por resina – Vitrebond (3M ESPE, e resina composta, Filtek™ Z350XT (3M ESPE, como controle negativo. Os corpos de prova foram imersos alternadamente em sistema de ciclagem de pH, permanecendo 6 horas na solução de desmineralização e 18 horas na de remineralização, sendo mantidos em estufa a 37°C. Liberação de flúor foi verificada 1, 2, 7 e 14 dias antes e após a recarga com flúor, com eletrodo específico acoplado ao aparelho analisador de pH/fluoretos, calibrado a cada medição com soluções de fluoreto de sódio a 1 e 10 ppm, preparadas com TISAB II. Para leitura, foi adicionado 0,5 mL da amostra a igual volume de TISAB II. Recarga foi realizada com flúor neutro 2% por 4 minutos nas amostras, lavadas e imersas novamente nas soluções do sistema de ciclagem de pH. Os dados foram submetidos à análise de variância e ao teste de Tukey (α=0,05. Resultado A liberação inicial de fluoreto (μgF/cm2 foi de 45,36; 37,49, e 26,35 para Maxxion R, Vitrebond e Ketac Molar EasyMix, respectivamente. Diferenças estatísticas significativas entre os materiais foram verificadas antes e após a recarga (p=0,001. Após a aplicação tópica de flúor, os cimentos de ionômero de vidro apresentaram capacidade de recarga de flúor. Conclusão Cimentos de ionômero de vidro avaliados foram capazes de liberar flúor em soluções de ciclagem de pH e podem recarregar flúor através da aplicação tópica.

  4. Ensaios de arrancamento e de empuxamento aplicados a taliscas de bambu encravadas em corpos-de-prova de solo-cimento Pull-out and push-in tests of bamboo splint embedded in soil-cement specimen

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    Wilza G. R. Lopes

    2002-12-01

    Full Text Available Neste trabalho, taliscas de bambu da espécie Dendrocalamus giganteus, engastadas em corpos-de-prova de solo-cimento, foram submetidas a ensaios de arrancamento (pull-out e de empuxamento (push-out a fim de se determinar sua resistência de aderência. Para esta finalidade, foi utilizado um solo-cimento feito a partir de um solo arenoso que continha aproximadamente 70% de areia. Corpos-de-prova de solo-cimento, de 15 cm de diâmetro e 30 cm de altura, foram moldados com 14% de cimento na umidade ótima de 10,7%. As taliscas de bambu foram preparadas com 2 cm de largura e comprimentos de 40, 50 e 60 cm, para o ensaio de arrancamento, e de 70 cm para o ensaio de empuxamento. Metade das taliscas foi deixada sem tratamento impermeabilizante e a outra metade foi revestida com emulsão asfáltica, impregnada com areia limpa grossa, para produzir uma superfície áspera e garantir melhor aderência com o solo-cimento. Os corpos-de-prova de solo-cimento com as taliscas de bambu engastadas, foram deixados a curar em câmara úmida, durante 28 d, antes de serem ensaiados. Ambos os ensaios foram realizados em uma máquina universal de ensaio adaptada, sendo as deformações medidas com um relógio comparador aferido, de sensibilidade igual a 0,01 mm. A resistência de aderência, quer fosse determinada pelo ensaio de arrancamento quer pelo ensaio de empuxamento, foi obtida dividindo-se a máxima carga verificada no ensaio pela área lateral da talisca de bambu efetivamente engastada no solo-cimento. Os melhores resultados foram obtidos sem aplicação de material impermeabilizante, para o ensaio de arrancamento, enquanto nenhuma diferença foi observada entre os dois tratamentos para o ensaio de empuxamento.In this study, Dendrocalamus giganteus bamboo splints (split culm embedded in soil-cement specimens were submitted to pull-out and push-in tests in order to determine its bonding strength. For this purpose a sandy soil was utilized. The 15.0 cm diameter

  5. Efeito da manipulação de cimentos de ionômero de vidro convencionais na microinfiltração de restaurações de classe ii em molares decíduos

    OpenAIRE

    Fernanda de Morais Ferreira

    2003-01-01

    Este estudo foi desenvolvido com o intuito de avaliar, comparativamente, o efeito do método de manipulação do cimento de ionômero de vidro (CIV) restaurador convencional na microinfiltração cervical de restaurações de classe II, em molares decíduos, in vitro. Para tanto, foram selecionados 40 segundos molares decíduos hígidos, extraídos por indicação ortodôntica ou naturalmente esfoliados e coletados por Odontopediatras da cidade de Belo Horizonte, com consentimento da criança e da sua famíli...

  6. Inclusão de digluconato de clorexidina em cimentos de ionômero de vidro para cimentação: análise das propriedades mecânicas e ação antibacteriana

    OpenAIRE

    Farret,Marcel Marchiori

    2010-01-01

    O tratamento ortodôntico predispõe o acúmulo de placa pela dificuldade de higiene por parte dos pacientes e pela grande quantidade de sítios para a proliferação bacteriana próximos aos bráquetes e principalmente anéis. Com base nisso, o objetivo deste estudo foi incluir digluconato de clorexidina (DGC) em cimentos de ionômero de vidro (CIVs) convencionais utilizados para a cimentação de anéis e verificar suas propriedades mecânicas e ação antibacteriana. Foram utilizados dois CIVs convenciona...

  7. Formação in situ de biofilme sobre esmalte e cimento de ionômero de vidro em diferentes tensões de oxigênio = In situ biofilm formation on enamel and glass ionomer cement in different oxygen tensions

    OpenAIRE

    Almeida, Vinícius Gomes

    2008-01-01

    Objetivo: Avaliar, in situ, o desenvolvimento de biofilme sobre fragmentos de esmalte bovino com restaurações de cimento de ionômero de vidro. Metodologia: Seis voluntários utilizaram um dispositivo intra-bucal removível, semelhante a um aparelho ortodôntico, contendo quatro espécimes de esmalte bovino restaurados com cimento de ionômero de vidro, posicionados para o meio bucal livre ou em contato com o palato. Um examinador cego analisou visualmente a formação de biofilme nos corpos-de-prova...

  8. Distribuição de elementos menores no processo de fabricação de clínquer portland

    OpenAIRE

    Paulo Eduardo Solak Sato

    2004-01-01

    O presente trabalho visou entender o comportamento da distribuição dos elementos menores em alguns fornos de cimento no Brasil, através de rastreamento de elementos menores nas matérias-primas, combustíveis, resíduos co-processados, emissões gasosas e clínquer portland. A importância deste estudo visa contribuir para um melhor entendimento do impacto no processo e na qualidade ambiental, decorrente do acréscimo de elementos menores, incluindo metais, no processo industrial de fabricação de cl...

  9. Evaluation of apical microleakage of teeth sealed with four different root canal sealers Avaliação da microinfiltração apical em dentes obturados com quatro diferentes cimentos endodônticos

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    Fábio Dultra

    2006-10-01

    Full Text Available OBJECTIVES: to compare the apical sealing ability of four root canal sealers. MATERIAL AND METHODS: forty extracted human maxillary canines were instrumented 1 mm short of the anatomical apex and randomly assigned to four groups (n=10, according to the root canal sealer used for obturation: Endofill, AH Plus, EndoREZ and Epiphany. Root canals were obturated with gutta-percha points, except for the Epiphany group, in which resin points (Resilon were used. The teeth were immersed in India ink for seven days and clarified using methyl salicylate. The extent of apical dye penetration was measured with a measuroscope in all aspects of the canal. RESULTS: AH Plus (0.02 mm ± 0.07, Epiphany (0.00 mm ± 0.00 and EndoREZ (0.32 mm ± 0.62 did not differ statistically to each other (p>0.01. EndoFill presented the highest dye penetration mean (0.83 mm ± 0.73 and was statistically different from the other sealers (pOBJETIVOS: comparar a capacidade de selamento apical de quatro cimentos endodônticos. MÉTODOS: quarenta caninos superiores humanos extraídos foram instrumentados 1 mm aquém do ápice anatômico e distribuídos aleatoriamente em quatro grupos (n=10, de acordo com o cimento endodôntico utilizado para a obturação: Endofill, AH Plus, EndoREZ e Epiphany. Os canais radiculares foram obturados pela técnica da condensação lateral com os cimentos e com cones de guta-percha, exceto o grupo do Epiphany, no qual os cones de resina (Resilon foram utilizados. Os dentes foram imersos em nanquim por sete dias e submetidos ao processo de diafanização e, então, clarificados empregando-se o salicilato de metila. A extensão de penetração via apical do corante foi medida por meio de um microscópio de mensuração em todas as faces do terço apical. RESULTADOS: AH Plus (0,02 mm ± 0,07, Epiphany (0,00 mm ± 0,00 e EndoREZ (0,32 mm ± 0,62 não diferiram estatisticamente entre si (p>0,01. EndoFill apresentou a maior média de penetração do corante (0

  10. A coincineração de resíduos em fornos de cimento: riscos para a saúde e o meio ambiente Co-incineration in cement kilns: health and environmental risks

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    Bruno Milanez

    2009-12-01

    Full Text Available O objetivo do artigo é discutir a forma como a coincineração de resíduos em fábricas de cimento vem crescendo no Brasil, bem como seus impactos sobre a saúde humana e o meio ambiente. Informações gerais sobre mercado e efeitos sobre a saúde foram obtidas através de revisão bibliográfica e alguns estudos de caso, escolhidos a partir de debate com integrantes da Rede Brasileira de Justiça Ambiental, foram construídos para ilustrar a situação no Brasil. Os estudos encontrados mostraram que, independente do nível de desenvolvimento tecnológico dos países, a saúde dos trabalhadores e das pessoas que moram próximas às fábricas de cimento vem sendo prejudicada pela poluição emitida pelas empresas de cimento, em especial por aquelas que praticam a coincineração. Além disso, no contexto brasileiro, a vulnerabilidade das instituições e populações afetadas tende a agravar este problema. Como conclusão, defende-se o aumento da capacidade institucional dos órgãos brasileiros responsáveis pelo monitoramento das atividades industriais, bem como uma rediscussão mais aprofundada dos aspectos políticos e éticos ligados ao transporte e comércio de resíduos industriais.In this article we discuss the development of hazardous waste co-incineration in cement kilns in Brazil as well as its impacts on health and the environment. Information was gathered through an extensive review on social and environmental impacts of co-incineration, and case studies, chosen after discussion with social movement representatives concerned with the co-incineration issue and related to the Brazilian Network on Environmental Justice, are described to illustrate the reality of co-incineration in Brazil. Studies showed that workers and community health suffers negative impacts from such practices in high-, middle- and low-income countries. In the Brazilian context, the institutional and social vulnerability intensifies these problems. To conclude, we

  11. Evaluation of cytotoxicity of two endodontic cements in a macrophage culture Avaliação da citotoxicidade de dois cimentos endodônticos em cultura de macrófagos

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    Celso Emanoel de Souza Queiroz

    2005-09-01

    Full Text Available Compared to gutta-percha, the endodontic cements are used in small quantity to seal root canals, but are indispensable to achieve hermetically sealed margins, where its biocompatibility depends on the sum of responses of each cell present in the periapical region. The object of this study was to evaluate the cytotoxicity of two endodontic cements, one based on epoxy resin (Sealer 26 and the other containing zinc oxide eugenol (Endofill by using cultured peritoneal macrophages from Swiss mice to measure the induced production of nitric oxide. After solidification and pulverization, aliquots of 100mul of suspension containing 18mg/mL of the respective cements were added to 96-well tissue culture plates containing the tissue culture of macrophages at a concentration of 5.0X10(6 cells/ml. In the positive control group the cell culture was treated with 10mg/mL of lipopolyssaccharide from Escherichia coli 026:B6 and the cell culture alone represented the negative control. After 48 hours of incubation, at 37ºC, in 5% CO2, the cultures were placed in an ELISA automatic reader to evaluate the release of nitric oxide. The production of nitric oxide for cement Sealer 26 was between 36.1 and 313.0 mumols, with a mean of 143.82±111.03mumols, while for the Endofill these values were significantly less (p=0.01, varying from 50.8 to 125.7mumols, with a mean of 80.33±28.42 mumols. In the positive and negative control groups the mean release of nitric oxide was of 162.75mumols and 4.42mumols, respectively. There was no significant difference between the positive control group and cement Sealer 26 (p>0.05. Therefore, the cement Sealer 26 caused significantly greater toxicity to the macrophages, possibly due to the components from the epoxy resin and formaldehyde release during polymerization.Comparativamente à guta-percha, os cimentos endodônticos são utilizados em pequena quantidade nas obturações dos canais radiculares, mas são imprescindíveis para

  12. Efeito da adição de cinza da casca de arroz em misturas cimento-casca de arroz Effect of the addition of rice husk ash in cement-rice husk mixtures

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    Loris L. Zucco

    2008-06-01

    Full Text Available A casca de arroz e sua cinza são abundantes e renováveis, podendo ser empregadas na obtenção de materiais de construção alternativos. O aumento do consumo desses resíduos poderia ajudar a minimizar os problemas ambientais provenientes da sua eliminação inadequada. Este trabalho teve o objetivo de avaliar a utilização de cinzas como carga mineral (filler. Todavia, a casca de arroz interferiu quimicamente no comportamento das misturas à base de cimento. Assim, diferentes misturas cimento-casca de arroz, com e sem adição de cinzas, foram avaliadas, a fim de destacar a influência de seus componentes (casca; cinza que, de outra forma, poderiam ser excluídas ou subestimadas. Amostras cilíndricas (teste de compressão simples e de tração por compressão diametral e amostras extraídas das placas prensadas (teste de flexão e compressão paralela à superfície foram usadas para avaliar o comportamento das misturas e dos componentes casca e cinza. Os resultados dos ensaios mecânicos mostraram, em geral, que não houve diferença estatística entre as misturas, as quais estão associadas ao efeito químico supressivo da cinza da casca de arroz. A mistura da casca de arroz de 10 mm com o acréscimo de 35% das cinzas destaca-se por permitir o mais elevado consumo de casca e cinzas, reduzir 25% no consumo de cimento e permitir o confinamento (sem emissões para a atmosfera de cerca de 1,9 tonelada de CO2 por tonelada de cimento consumido, contribuindo, assim, para a redução da emissão de CO2, o que pode incentivar construções rurais sob o ponto de vista ecológico.The rice husk and its ash are abundant and renewable and can be used to obtain alternative building materials. An increase in the consumption of such waste could help minimize the environmental problems from their improper disposal. This study aimed to evaluate the use of ashes as a cargo mineral (filler. However, the rice husk chemically interferes in the conduct of the

  13. Avaliação in vitro da liberação e da recarga de flúor em cimentos de ionômero de vidro

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    Evelyn Lopez Leite

    Full Text Available OBJETIVO: Este estudo avaliou a absorção de íons flúor em cimentos de ionômero de vidro de manipulação mecânica e manual, por uma única aplicação tópica de flúor. METODOLOGIA: Os cimentos de ionômeros de vidro (CIVs Riva Self Cure® (RSC-SDI e Ketac Molar Easymix® (KME- 3M-ESPE foram testados com um material controle (RC-resina composta ICE-SDI, após preparo de dez corpos de prova de cada um (n = 30. Esses corpos foram pesados e armazenados em água deionizada para as aferições da liberação de flúor (eletrodo específico, Orion 9606-BN em dois períodos: antes (PI: 1, 2, 7 e 14 dias e após aplicação tópica de flúor (PII: 16, 17, 18, 20, 22, 24, 26, 28 e 30 dias. No 15.º dia, cinco espécimes de cada material (n = 15 foram submetidos à aplicação tópica de fluoreto de sódio neutro a 2% ou de gel placebo de Natrosol (n = 15. RESULTADO: A maior liberação de íons flúor para ambos os CIVs ocorreu no primeiro dia do PI (KME = 13,44 ± 6,05; RSC = 6,88 ± 0,62 e a quantidade liberada foi semelhante no PII (KME = 6,22 ± 0,80; RSC = 6,67 ± 1,63. A comparação entre os períodos mostrou diferença significante somente para o KME, com maior liberação de flúor no PI (p 0,05. A análise de variância e o teste de Tukey (p < 0,05 não indicaram diferenças significantes entre os materiais antes e após a recarga. CONCLUSÃO: Os CIVs de manipulação mecânica ou manual possuem habilidade semelhante para captar íons flúor, quando submetidos a uma única aplicação tópica de fluoreto de sódio a 2%.

  14. Fine natural aggregate replacement for sandy residue from itabirite exploitation in Portland cement mortar; Substituicao dos agregados miudos naturais por residuo arenoso gerado no beneficiamento do itabirito em argamassas de cimento Portland

    Energy Technology Data Exchange (ETDEWEB)

    Melo, V.A.R. [Rede Tematica em Engenharia de Materiais (REDEMAT), MG (Brazil); Freire, C.B.; Pereira Junior, S.S.; Lameiras, F.S.; Tello, C.C.O., E-mail: cbf@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2011-07-01

    The fine natural aggregates are a material largely used by the civil construction for mortar and concrete production. Due to tightening legal restrictions imposed on their extraction, alternative materials are being considered. The use of sandy residue from BIF (banded iron formations) exploitation was investigated. It requires their grinding and flotation to concentrate iron oxides. Large amounts of sandy residue composed of quartz and iron oxides are generated in this process. The sandy residue was characterized relative to mineralogical composition, particle size distribution, presence of organic impurities, and particle shape. Mortar formulations were prepared by varying the type of cement, the cement to aggregate proportion and the water/cement ratio (a/c). The results of viscosity and density of fresh mortar, setting time, and compressive strength are presented. Compressive strength up to 19.5 MPa at 28 days were achieved with the use of cement CPV, a/c ratio of 0.80 and cement:aggregate proportion of 1:2. The results demonstrate the technical feasibility of using sandy residue as fine aggregate. (author)

  15. CONFORTO TÉRMICO EM GALPÕES AVÍCOLAS, SOB COBERTURAS DE CIMENTO-AMIANTO E SUAS DIFERENTES ASSOCIAÇÕES

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    Sandra Regina Pires de Moraes

    1999-04-01

    Full Text Available RESUMO Realizou-se um experimento com modelos reduzidos de galpões avícolas, usando-se telhas de cimento-amianto como testemunha e associações de forro de polietileno, aspersão de água sobre a cobertura, dupla lâmina reflexiva de alumínio sob a cobertura, pintura branca na face superior da telha, poliuretano na face superior da cobertura, poliuretano na face inferior, com o objetivo de se estudar o conforto térmico no interior dos modelos, através do Índice de Temperatura de Globo e Umidade (ITGU e da Carga Térmica de Radiação (CTR obtidos na altura do centro de massa das aves, a cada 2 horas, das 8 às 18 horas, com 15 repetições/tratamento, durante o verão. Todos os tratamentos possibilitaram redução nos valores de ITGU, sendo o mais eficiente a aspersão, seguido do forro de polietileno. Para a CTR, o mais eficiente foi com forro de polietileno, seguido por aspersão. A eficiência mínima foi observada no tratamento de poliuretano na face inferior da cobertura.

  16. Comportamento cíclico de misturas de cimento

    OpenAIRE

    Sara Rios; António Joaquim Pereira Viana da Fonseca

    2009-01-01

    Este artigo apresenta os resultados de ensaios triaxiais cíclicos realizados com instrumentação de alta precisão sobre várias misturas de areia siltosa e cimento preparadas com distintos valores de índice de vazios e teores de cimento. Os ensaios tiveram por base os princípios expressos na metodologia da pré-norma CEN (2004) sendo a análise efectuada em termos do módulo resiliente e da deformação permanente e da sua evolução com o número de ciclos e nível de tensão.

  17. Retention of oral microorganisms on conventional and resin-modified glass-ionomer cements Retenção de microrganismos bucais em cimentos de ionômero de vidro convencionais e modificados por resina

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    Denise PEDRINI

    2001-09-01

    Full Text Available Secondary caries are a worldwide public and socioeconomic problem. The placement of restorations can lead to the development of environmental conditions favorable to microbial colonization, especially on the tooth/restoration interface, which is a predisposing factor for secondary caries. The aim of this study was to evaluate microbial retention on conventional (Chelon-Fil and Vidrion R and resin-modified (Vitremer and Fuji II LC glass-ionomer cements, in situ, using a hybrid composite resin (Z100 as a control. Twelve volunteers wore Hawley appliances with specimens made of all tested filling materials for 7 days. The specimens were then removed from the appliances and transferred to tubes containing 2.0 ml of Ringer-PRAS. Microorganisms from the samples were inoculated onto blood agar and Mitis Salivarius Bacitracin agar and incubated under anaerobiosis (90% N2, 10% CO2, at 37°C, for 10 and 2 days, respectively. The resin-modified glass-ionomer cements and the composite resin retained the same levels of microorganisms on their surfaces. The resin-modified glass-ionomers retained less mutans streptococci than the composite resin and conventional glass-ionomer cements. The conventional glass-ionomer cements retained less mutans streptococci than the composite resin, but that difference was not statistically significant.A cárie secundária representa problema de saúde pública e socioeconômico no mundo. A restauração de dentes acometidos por cárie pode criar condições favoráveis à proliferação microbiana na superfície do material restaurador ou na interface dente/restauração, criando ambiente propício para o estabelecimento de cárie secundária. O objetivo deste estudo foi avaliar a capacidade de retenção de placa bacteriana em cimentos de ionômero de vidro convencionais (Chelon-Fil e Vidrion R e modificados por resina (Vitremer e Fuji II LC e de resina composta híbrida (Z100, utilizada como controle. Nos testes de reten

  18. CONSTRUCTION AND DEMOLITION WASTE USE IN SOIL – CEMENT = APLICAÇÃO DO RESÍDUO DE CONSTRUÇÃO E DEMOLIÇÃO EM SOLO – CIMENTO

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Nobrega

    2005-01-01

    empreendendo ações para o reaproveitamento desses resíduos como agregado para pavimentação, fechamento de valas e confecção de artefatos de concreto. Há, entretanto, necessidade de sua utilização em maior escala, possibilitando que estes materiais passem a constituir alternativaseconomicamente viáveis. Assim, propõe-se sua utilização como agregado no compósito solo-cimento. Foram testadas propriedades físicas, tecnológicas e químicas de misturas contendo resíduo de construção civil reciclado e solo em diferentes proporções resíduo/solo. Verificou-se que as misturas nas proporções de 50%, 75% e 100% atendem às especificações tecnológicas para emprego como solocimento.Quanto aos aspectos químicos, a utilização do resíduo como agregado nosolo-cimento se mostrou exeqüível e eficiente no encapsulamento de contaminantes.

  19. Análise comparativa da resistência de união de um cimento convencional e um cimento autoadesivo após diferentes tratamentos na superfície de pinos de fibra de vidro

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    Juliana das Neves MARQUES

    Full Text Available Resumo Introdução Os pinos de fibra de vidro são uma alternativa aos núcleos metálicos e apresentam vantagens, tais como: estética, módulo de elasticidade semelhante à dentina e cimentação imediata após o término do tratamento endodôntico. Ainda, apresentam a capacidade de aderir ao cimento resinoso e este, à dentina, por meio de técnicas adesivas. Objetivo Comparar a adesão de um cimento resinoso convencional e um autoadesivo a pinos de fibra de vidro, e os efeitos de diferentes tratamentos de superfície na resistência adesiva dos pinos. Material e método Trinta pinos foram divididos em três grupos: Controle: sem tratamento na superfície; Jateamento: jateamento com óxido de alumínio por 30 segundos, e Peróxido: imersão em peróxido de hidrogênio 24% por um minuto. Em seguida, corpos de prova foram obtidos a partir de cilindros de cimento resinoso contendo o pino de fibra posicionado no centro de seu longo eixo. Em cada grupo, cinco pinos foram associados ao adesivo Âmbar + cimento convencional AllCem Core e os outros cinco pinos, ao cimento autoadesivo RelyX U200. O conjunto pino/cimento foi segmentado e avaliado em relação à resistência de união (RU por push-out. Os dados foram analisados estatisticamente pelos testes de ANOVA e Tukey (p<0,05. Resultado Os cimentos avaliados exibiram valores de RU semelhantes. Em relação aos tratamentos de superfície, os maiores valores de RU foram encontrados no grupo Jateamento. Conclusão O cimento convencional, AllCem Core, e o cimento autoadesivo, RelyX U200, mostraram valores de resistência de união semelhantes. Ainda, o jateamento com óxido de alumínio favoreceu a adesão dos pinos aos cimentos.

  20. Surface roughness average and scanning electron microscopic observations of resin luting agents Alteração de rugosidade superficial e observações em microscopia eletrônica de varredura de cimentos resinosos

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    Rafael Francisco Lia Mondelli

    2003-12-01

    Full Text Available The objective of this work was to evaluate the surface roughness changes of three current resin cements after tooth brushing simulation, as well as discuss its relation with scanning electron microscopic observations. The materials employed were Enforce Sure Cure (Dentsply, Rely X (3M-ESPE and Variolink II (Vivadent. They were subjected to brushing abrasion (100,000 strokes for each specimen and the surface roughness alterations (before and after strokes were detected. For each roughness test condition, specimens were coated with gold-palladium and observed on a DSM 900 Zeiss scanning electron microscope. Roughness changes values (Ra were statistically increased after brushing strokes. Based on the microscopic observations and roughness changes analysis, all cements studied became rougher after brushing strokes.O objetivo desse estudo foi avaliar a alteração de rugosidade superficial de três cimentos resinosos após submetê-los a ciclos de escovação simulada e analisar qualitativamente a sua superfície através de observações microscópicas. Os materiais empregados neste estudo foram Enforce Sure Cure (Dentsply, Rely X (3M-ESPE e Variolink II (Vivadent. Estes foram submetidos à ciclos de escovação simulada (100.000 ciclos para cada espécime e a alteração de sua rugosidade superficial (antes e após escovação foi avaliada. Para cada material e condição de rugosidade, espécimes foram selecionados, metalizados e observados em microscopia eletrônica de varredura (DSM 900 Zeiss. Baseado nas observações microscópicas e nos valores de alteração de rugosidade, todos os materiais apresentaram aumento de rugosidade aritmética (Ra após ciclos de escovação simulada.

  1. O cimento de ionômero de vidro na odontologia

    OpenAIRE

    2006-01-01

    O Cimento de ionômero de vidro foi inventado no início da década de 70 do século passado, a partir do desenvolvimento do cimento de silicato. Desde então, passou a exercer um papel significante na odontologia restauradora. Primeiramente, era utilizado apenas como material restaurador em cavidades pequenas, posteriormente, passou a ser utilizado como material de cimentação de peças protéticas, como núcleo de preenchimento, material para base e forramento de cavidades dentárias e selamentos de ...

  2. Efeito de aditivos minerais sobre as propriedades de chapas cimento-madeira Effect of minerals additives on the properties of wood cement-bonded particleboard

    Directory of Open Access Journals (Sweden)

    Gilmar Correia Silva

    2006-06-01

    Full Text Available O objetivo deste trabalho foi avaliar o efeito da adição de dois tipos de aditivos minerais (microssílica e metacaulim sobre as propriedades de chapas de cimento-madeira, aplicando-se diferentes teores aditivos (0, 20 e 30%. O aglomerante empregado na produção dos painéis foi o cimento Portland tipo ARI, juntamente com partículas de madeira de Eucalyptus urophylla. Os resultados indicaram que a adição dos aditivos minerais não causou melhorias significativas nas propriedades mecânicas avaliadas. Já, em relação às propriedades físicas, o efeito positivo da adição de 20% de microssílica pôde ser observado no ensaio de absorção em água após a imersão em 2 e 24 horas. O aditivo metacaulim não apresentou tendência clara, porém, de forma geral, a sua adição causou redução na qualidade das chapas.The objective of this work was to evaluate the effect of the two minerals additives (microsilica and meta-kaolin on the properties of wood cement-bonded particleboard (WCBP with different amounts (0%, 20% and 30% of additives. Portland cement of high initial resistance was used in the production of panels as binder material. It was mixed with Eucalyptus urophylla wood particles to boards formation. The results indicated that the addition of mineral additives did not cause significant improvements in the evaluated mechanical properties. For physical properties, the positive effect of the addition of 20% microsilica can be observed on the absorption in water properties after 2 and 24 hours. The additive meta-kaolin did not present a clear trend, but, in general, the addition of this additive caused a reduction in the quality of boards.

  3. Avaliação do impacto na infestação por Aedes aegypti em tanques de cimento do município de Canindé, Ceará, Brasil, após a utilização do peixe Betta splendens como alternativa de controle biológico

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    Pamplona Luciano de Góes Cavalcanti

    2004-01-01

    Full Text Available Canindé apresenta uma população de 71.235 habitantes. Em abril de 2001 iniciou a utilização de peixes larvófagos em tanques de cimento, localizados ao nível do solo, como forma de controle biológico para larvas de Aedes aegypti. Durante a visita do agente, ao invés de se tratar os tanques com larvicida, colocou-se um espécime do peixe Betta splendens por depósito. O presente trabalho teve como objetivo avaliar os resultados desta intervenção. Com os levantamentos do número de imóveis e depósitos existentes, estimou-se este número mês a mês determinando então o número de depósitos existentes por imóvel. Com esta estimativa e o número de imóveis visitados mensalmente analisou-se a infestação deste tipo de depósito. Em janeiro de 2001, 70,4% dos tanques examinados apresentavam larvas; e apenas 7,4% em janeiro de 2002. Em dezembro de 2002 este índice caiu para 0,2%. Demonstrou-se com clareza a capacidade do Betta splendens como agente de controle biológico, em tanques de cimento, reduzindo 320 vezes a infestação deste tipo de recipiente de grande volume.

  4. Gradientes térmicos em whitetopping ultradelgado na pista experimental instrumentada na USP

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    Deividi da Silva Pereira

    2009-12-01

    Full Text Available

    Este trabalho apresenta, primeiramente, uma sucinta descrição da execução de um trecho experimental de <em>Whitetopping em>Ultradelgado (WTUD no campus da Universidade de São Paulo (USP bem como de sua instrumentação. São apresentados e discutidos os resultados referentes a temperaturas obtidos por esta instrumentação durante o outono, analisando as diferenças encontradas nos diferenciais térmicos para placas de diferentes dimensões, obtidos por termoresistores instalados nos cantos, bordas e centro das mesmas. Com base em medidas de deformação obtidas por <em>strain-gages em>são avaliados valores típicos das tensões induzidas no WTUD pelo efeito isolado do gradiente térmico sobre as placas de concreto de cimento Portland (CCP.

  5. Compósitos à base de cimento reforçado com polpa celulósica de bambu. Parte II: Uso de resíduos cerâmicos na matriz Cement-based composite reinforced with bamboo pulp. Part II: Use of ceramic residues in matrix

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    Marcos A. S. dos Anjos

    2003-08-01

    Full Text Available Este é o segundo dos dois artigos relativos aos resultados experimentais da combinação de matriz cimentícia reforçada com polpa celulósica de bambu. Neste trabalho, são mostrados os resultados da investigação da substituição parcial do cimento por resíduo de fábrica de blocos cerâmicos. O cimento foi substituído em percentagens de 20, 30 e 40% em relação à massa de cimento. Essas combinações foram reforçadas com polpa de bambu refinada. Os procedimentos e programas experimentais foram os mesmos adotados no artigo anterior (Parte 1. Considerando-se os resultados dos ensaios de obtenção das propriedades mecânicas, a substituição de 20% foi a que apresentou melhor performance.This paper is the second part of a series of two articles concerning the experimental results of newly developed composite with cementations matrix reinforced with bamboo pulp. In this part the results of the investigations concerning the partial substitution of Portland cement by grinded residues from a brick factory are presented. The cement was partially replaced in percentages of 20, 30 and 40% by weight. These composites were reinforced with only refined bamboo pulp. The same procedures described in Part I were adopted and used in the experimental program. Considering the results of the mechanical properties it is verified that 20% of cement replacement presented the best results.

  6. Obtenção e utilização de microesferas de parafina para confecção de arcabouços teciduais baseados em cimento de α-fosfato tricálcico Production and use of paraffin microspheres for tissue scaffolds based on α-tricalcium phosphate cement

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    J. L. de M. Machado

    2009-06-01

    Full Text Available Um dos fatores mais importantes na técnica conhecida por engenharia de tecidos é o crescimento de células em suporte porosos tridimensionais conhecidos por arcabouços. Os arcabouços guiam o crescimento celular e facilitam a formação de tecidos e órgãos funcionais. Cimentos ósseos são materiais desenvolvidos há aproximadamente uma década para aplicações biomédicas. Um cimento deste tipo pode ser preparado misturando um sal de fosfato de cálcio com uma solução aquosa para que se forme uma pasta que possa reagir à temperatura corporal dando lugar a um precipitado que contenha hidroxiapatita. O desenvolvimento de estruturas porosas de cimento de fosfato de cálcio é de grande utilização em engenharia de tecidos, além de outras áreas da traumatologia. O objetivo deste trabalho foi o uso de cimento de α-TCP (α-fosfato tricálcico para obtenção desses arcabouços, através da obtenção e utilização de esferas de parafina como corpos geradores de poros. O α-TCP foi sintetizado por resfriamento brusco de seus precursores e, as esferas foram produzidas por suspensão em uma solução aquosa de poli (álcool vinílico e sulfato de sódio. As quantidades de cada um destes reagentes foram estudadas com relação ao tamanho das esferas formadas. Pela análise de difração de raios X foi detectada a presença de β-TCP como fase indesejada no processo de síntese do α-TCP e de hidroxiapatita deficiente em cálcio após a reação de pega do cimento. Foi analisada a extração da parafina dos arcabouços por utilização de um método térmico. A porosidade dos arcabouços confeccionados com esferas de parafina foi observada por microscopia eletrônica de varredura, mostrando tamanho, forma e interconectividade dos corpos porosos, que se mostrou adequada para o crescimento celular.One of the most important factors in tissue engineering is the three-dimensional cells growth in porous support known by scaffolds. The scaffolds

  7. Borracha de pneus como modificador de cimentos asfálticos para uso em obras de pavimentação

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    Sandra Oda

    2001-05-01

    Full Text Available Este trabalho apresenta estudo sobre a incorporação de borracha de pneus em ligantes asfálticos utilizados em obras de pavimentação. Trata-se de uma alternativa para solucionar um grave problema ambiental, pois no Brasil, anualmente, são descartados mais de 30 milhões de pneus, dos quais a maior parte é disposta em locais inadequados, servindo para a procriação de vetores de doenças e representando risco de contaminação do meio-ambiente. Os efeitos dos principais fatores que condicionam o comportamento do ligante asfalto-borracha (teor e granulometria da borracha, temperatura de mistura, tempo de reação são avaliados através de ensaios tradicionais de caracterização de ligantes asfálticos e ensaios do Método Superpave, diretamente relacionadas ao desempenho dos pavimentos no campo. Os resultados da análise estatística evidenciam o efeito preponderante do teor de borracha e, principalmente, que o ligante asfalto-borracha pode aumentar a resistência ao acúmulo de deformação permanente e ao aparecimento de trincas por fadiga do revestimento

  8. Degradação da fibra de coco imersa em soluções alcalinas de cimento e NaOH

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    Everton J. da Silva

    2015-10-01

    Full Text Available RESUMORealizou-se este trabalho com o objetivo de analisar os efeitos que soluções aquosas alcalinas exercem sobre a fibra de coco, em função do tempo. O processo pretende simular, de forma acelerada, as condições de degradação que ocorrem nas fibras de coco inseridas em matrizes cimentícias. As fibras inseridas em soluções alcalinas com diferentes concentrações foram analisadas através de gravimetria, microscopia eletrônica de varredura e espectrometria na região do infravermelho. As soluções foram estudadas através da técnica da medição de absorção por ultravioleta, durante o segundo semestre de 2013. De acordo com o aumento da concentração das soluções e do tempo de contato com as fibras de coco, houve uma modificação maior da superfície da fibra através da retirada dos constituintes superficiais, como cutículas, partículas globulares, cavidades e também lignina.

  9. Modelagem e análise de transferência de calor de um resfriador de clínquer tipo satélite para forno de cimento

    OpenAIRE

    2014-01-01

    O concreto, com seu principal componente, o cimento, é, o material de maior importância em construções no mundo. Para a fabricação do cimento, o clínquer é o principal constituinte e é fabricado em um processo de pirólise em fornos rotativos. Resfriadores de clínquer são equipamentos utilizados após o forno. O resfriador do tipo grelha é o equipamento mais utilizado atualmente nesse processo. Entretanto, o grande número de plantas de fornos de cimento com resfriadores tipo satélite (ou planet...

  10. Processo de trabalho e riscos para a saúde dos trabalhadores em uma indústria de cimento The work process and occupational health risks in a cement factory

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    Fátima Sueli Neto Ribeiro

    2002-10-01

    Full Text Available A avaliação do processo de trabalho sobre a saúde de trabalhadores de uma fábrica de cimento, localizada no Estado do Rio de Janeiro, é relatada. A metodologia interativa utilizada, constou de distintas formas de avaliação do ambiente de trabalho através da incorporação de várias instituições, com atribuição na área de Saúde do Trabalhador, de técnicos de diversas formações, do sindicato e da valorização da experiência do trabalhador, contribuindo ativamente no processo de vigilância do SUS. Os níveis de material particulado e de ruído foram medidos. O porcentual médio de sílica livre cristalina encontrado no material particulado, foi de 2%, o que resultou em um limite de tolerância, determinado como especificado na Legislação Brasileira (NR-15, de 2,0mg/m³. A concentração de partículas, tanto em amostras coletadas em nível da zona respiratória dos trabalhadores, quanto às amostras de área, variou de 3,59 a 52,44mg/m³, o nível de ruído situou-se entre 83dB e 110dB. A maioria dos valores encontrados superam o valor limite estabelecido pela Legislação Brasileira. Esses resultados, somados ao registro do olhar dos trabalhadores, revelaram um ambiente e processo de trabalho insalubre, colocando em risco a saúde dos operários.The authors evaluate the work process and its effect on workers' health in a cement factory in the State of Rio de Janeiro. The interactive methodology consisted of different approaches to assessing the workplace through the incorporation of various institutions working in the field of Workers' Health, professionals from different backgrounds, and the trade union, valorizing the workers' experience and actively contributing to the surveillance process under the Unified National Health System (SUS. Levels of particulate matter and noise were measured. The mean level of free crystalline silica in the particulate matter was 2%, resulting in a tolerance limit as specified under Brazilian

  11. The influence of cement type and admixture on life span of reinforced concrete utility poles subjected to the high salinity environment of Northeastern Brazil, studied by corrosion potential testing A influência do tipo de cimento e adição na vida útil de postes de concreto armado submetidos ao ambiente de alta salinidade do Nordeste do Brasil, estudada pela técnica de potencial de corrosão

    Directory of Open Access Journals (Sweden)

    A. Joukoski

    2004-03-01

    é conhecido como um dos mais agressivos destes elementos, causando, entre outros danos, corrosão da armadura de aço e posterior degradação da matriz de concreto. O objetivo deste trabalho foi determinar a influência do tipo de cimento na resistência e durabilidade de corpos-de-prova de concreto armado com 25 mm de cobrimento, quando submetido a envelhecimento em uma solução aquosa de 3,4% de cloreto de sódio e pela exposição a uma atmosfera marinha de alta salinidade. Postes de concreto armado foram confeccionados seguindo a um mesmo procedimento de mistura e, após o período de cura, foram expostos à atmosfera em uma estação de corrosão situada próximo de Aracaju, estado de Sergipe, na costa nordeste do Brasil. Dois traços de concreto foram elaborados usando-se cimento CPII-F 32 (cimento Portland composto com fíler: uma mistura sem qualquer adição e uma com adição de 8% de sílica ativa, em substituição aos agregados miúdos. Uma outra mistura foi preparada com cimento CPV-ARI RS (cimento Portland de alta resistência inicial, resistente a sulfatos. Todas as três misturas foram definidas para um consumo de cimento de aproximadamente 350 kg/m³. O desempenho das estruturas foi avaliado a partir dos resultados de testes físico-químicos, mecânicos e eletroquímicos, após mais de um ano de envelhecimento natural. Os potenciais de corrosão dos corpos-de-prova de concreto armado e dos postes confeccionados foram medidos em função do tempo de envelhecimento no ambiente natural e sob envelhecimento acelerado por íon cloreto no laboratório. As medidas de potencial de meia-célula mostraram que os melhores resultados foram obtidos pela mistura contendo cimento CPII-F 32 e sílica ativa, seguidos pelo concreto preparado com cimento CPV-ARI RS. A mistura feita apenas com cimento CPII-F 32 apresentou o pior desempenho em termos de durabilidade.

  12. Carbonated deep in non-NBR 9831/2006 Portland cements in oil well; Carbonatacao em cimentos nao especificados pela Norma NBR 9831/2006 quando empregados em pocos de petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Hastenpflug, D.; Moraes, M.K.; Dalla Vecchia, F.; Costa, E.M. [Pontificia Univ. Catolica do Rio Grande do Sul (PUC-RS), Porto Alegre, RS (Brazil). Centro de Excelencia em Pesquisa sobre Armazenamento de Carbono (CEPAC); Pontificia Univ. Catolica do Rio Grande do Sul (PUC-RS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia e Tecnologia de Materiais (PGETEMA)], Email: hasten@gmail.com; Abreu, J.V. [Holcim Brasil S.A., Sao Paulo, SP (Brazil). Centro Tecnologico

    2010-07-01

    The NBR 9831/2006 well cements are indicated to well completions to sequestration of CO{sub 2} in geologic formations, being cement class G the most popular. However, studies have shown that Class G cement might suffers considerable degradation due to exposure to CO{sub 2} under geologic sequestration conditions. In order to increase cement resistance to acid attack, admixtures and additives as fly ash, fume, limestone and mineral wastes have been investigated. In this paper experiments were conducted to evaluated four commercial non- NBR 9831/2006 cements generally used in pavement area, in cracks completion and in concretes for use in aggressive environments. These cements were chosen because they have mineral additive into their specifications. This paper analyses the carbonated deep after accelerated carbonation reaction tests that simulate the well's geological conditions, when exposed to water saturated with supercritical CO{sub 2} and wet supercritical CO{sub 2} at 70 deg C and 15 MPa, during 7 days. In addition, compressive strength and the workability of these pastes were evaluated. The results were compared to the ones realized at the same condition with cement class G. It was observed that the cement used in pavement area (Pavifort) has a good resistance to CO{sub 2} attack when compared to the other types of cement, but its compressive strength is very low. (author)

  13. Analysis of the film thickness of a root canal sealer following three obturation techniques Análise da espessura da linha de cimento endodôntico em três técnicas de obturação

    Directory of Open Access Journals (Sweden)

    Gustavo André De Deus

    2003-06-01

    Full Text Available The aim of this study was to obtain a quantitative analysis of the film thickness of a root canal sealer formed after filling by three different techniques. Thirty human maxillary incisors were selected and access cavities were prepared using high-speed diamond stones and water spray. A size #15 K-Flexofile was introduced in the canal of each specimen until it was seen just at the apical foramen. The working length was determined to be 1 mm short of that position and the canals were prepared to an apical size of #45 K-Flexofile. Copious irrigation with 5.25% NaOCl (sodium hypochlorite was used during and after instrumentation. The samples were divided into three groups and obturated as follows: G1 - lateral condensation, G2 - lateral condensation with an accessory cone, and G3 - continuous wave of condensation. The samples were evaluated in the cervical, middle and apical thirds. The film thickness of the root canal sealer was measured through a microscopic evaluation. Statistical analysis was obtained using the Wilcox test. Statistical analysis showed significant differences between G3 and G1, G3 and G2 (p O objetivo deste estudo foi realizar uma análise quantitativa da espessura da linha de cimento endodôntico formada por três técnicas de obturação. Trinta incisivos centrais superiores humanos foram selecionados e acessados de modo convencional. Uma lima nº 15 K-Flexofile foi usada para a verificação da patência foraminal e para determinação do comprimento de trabalho, que foi estabelecido a 1 mm aquém do forame apical. Os canais foram preparados até a lima nº 45. Hipoclorito de sódio a 5,25% foi usado durante toda a instrumentação. Os dentes foram divididos em 3 grupos e obturados pelos seguintes critérios: G1 - condensação lateral; G2 - compressão hidraúlica e G3 - onda de condensação. Os dentes foram seccionados e analisados nos terços cervical, médio e apical. A espessura do filme de cimento foi determinada por

  14. Avaliação in vitro da infiltração via coronária em função de diferentes cimentos endodônticos resinosos =An in vitro evaluation of coronal leakage of different resin-based endodontic sealers

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    Martins, Alessandra de Souza et al.

    2006-01-01

    Full Text Available O objetivo desta pesquisa foi avaliar a infiltração coronária permitida por diferentes cimentos endodônticos resinosos. Foram utilizados 44 pré-molares humanos extraídos. Após a eliminação das coroas dentárias, as raízes foram padronizadas em 15 mm. O preparo do canal foi realizado pela técnica escalonada regressiva, empregando-se como solução irrigadora o NaOCl 1% e ao final EDTA. Realizada a impermeabilização da superfície externa, com uma camada de cola Araudite® e duas de esmalte para unhas, os canais radiculares foram obturados pela técnica do cone único de guta-percha, empregando-se diferentes cimentos resinosos, de acordo com os grupos experimentais: G1 – AH Plus®; G2 – experimental MBP; G3 – EndoREZ® e G4 – AH 26®. Quatro dentes foram utilizados como controle (positivo e negativo. Em seguida, foram imersos em tinta nanquim por 15 dias a 37°C e 100% de umidade. Decorrido este período as raízes foram lavadas por 24 horas e submetidas ao processo de diafanização (descalcificação em ácido nítrico 5%, desidratação em bateria de álcool ascendente e transparência em salicilato de metila. A análise da infiltração coronária foi realizada por meio de escores numéricos, através de microscópio com aumento de 40×. O teste estatístico de Kruskal-Wallis mostrou que o cimento EndoREZ® apresentou o pior resultado e diferença estatística significante com relação aos demais grupos, que não apresentaram diferença estatística significante entre si (p The aim of this study was to evaluate the coronal leakage of four different endodontic sealers. Forty-four extracted human pre-molars constituted the sample. Theirs crowns were cut and the roots standardized in 15 mm. The canals were prepared by the step-back technique, using NaOCl 1% and EDTA for irrigation. The specimens were recovered with Araudit® and then with two layers of nail varnish. The canals were obturated by the single cone gutta

  15. Modelagem heurística no problema de distribuição de cargas fracionadas de cimento.

    OpenAIRE

    Marcos Miura

    2008-01-01

    Esta dissertação trata do problema do agrupamento de cargas fracionadas na distribuição de cimento ensacado partindo de um depósito central. O problema consiste em definir quais entregas de cimento serão carregadas juntas em um determinado veículo, de modo a aproveitar ao máximo sua capacidade e ao mesmo tempo reduzir o custo com o frete pago aos transportadores que farão sua distribuição. Em especial, o método de resolução proposto pode ser dividido em três fases. Na primeira fase, as entreg...

  16. Incidência de ocratoxina A em diferentes frações do café (Coffea arabica L.: bóia, mistura e varrição após secagem em terreiros de terra, asfalto e cimento Incidence of ochratoxin A in fraction diferents coffee beans (Coffea Arabica L: "boia", mixes and "varrição"

    Directory of Open Access Journals (Sweden)

    Luís Roberto Batista

    2007-06-01

    Full Text Available A incidência de ocratoxina A foi estudada em café mistura, bóia e varrição secas em três tipos de terreiro: terra, cimento e asfalto. Foram analisadas 238 amostras coletadas em 11 municípios da região sul do Estado de Minas Gerais, sendo 35 bóia, 97 - mistura e 106 varrição. Das amostras analisadas, em 40% não foi detectada a presença de ocratoxina A, em 31%, foram detectadas a presença de ocratoxina A em níveis que variaram de 0,1 a 5,0 µg/Kg de café. Estes resultados demonstram que 169 amostras (71% analisadas estariam dentro dos limites em estudo da Legislação Européia que regulamenta a concentração máxima de ocratoxina A em grãos de café torrado. As espécies de Aspergillus identificadas como produtoras de ocratoxina A foram Aspergillus ochraceus, A. sclerotiorum e A. sulphureus. Os níveis de contaminação de ocratoxina A em grãos de café foram maiores na fração varrição e nas frações bóia e mistura, secas em terreiro de terra. Os resultados deste estudo concluem que o terreiro de terra aumenta o risco de contaminação com ocratoxina A em grãos de café. A fração varrição devido aos riscos de exposição a ocratoxina A, deve ser reduzida através da adoção de boas práticas agrícolas e não ser utilizada para fins de consumo humano e animal.The ochratoxin incidence was studied in coffee it mixes, it "bóia" and "varrição" dry in three yard types: earth, cement and asphalt. 238 samples were analyzed collected in 11 municipal districts of the south of Minas Gerais state, being 35 "bóia", 97 - it mixes and 106 varrição. Of the analyzed samples, in 40% the ochratoxin A presence it was not detected, in 74 samples, 31%, ochratoxin A presence were detected the in levels that varied from 0,1 to 5,0 µg/Kg of coffee beans. These results demonstrate that in 169 samples (71% analyzed they would be inside of the limits in study of the European Legislation that regulates the maximum concentration of

  17. Chapas de cimento-madeira com resíduos da indústria madeireira da Região Amazônica

    OpenAIRE

    2012-01-01

    Este estudo teve como objetivo avaliar o emprego do resíduo da indústria madeireira da região da Amazônia brasileira na produção de material compósito cimento-madeira. Foi avaliada a compatibilidade de seis espécies de dicotiledôneas nativas da Amazônia com o cimento CP V ARI por meio da realização de ensaios de compressão axial em corpos de prova cilíndricos. Os resíduos foram utilizados ao natural e submetidos ao tratamento de lavagem em água quente por 2 h. A relação cimento-madeira foi de...

  18. Addition of polyurethane dispersions to Portland G for oil wells steam injection submitted to vapor injection; Adicao de poliuretana em dispersao a Portland G para cimentacao de pocos de petroleo sujeitos a injecao de vapor

    Energy Technology Data Exchange (ETDEWEB)

    Silva, L.B. da; Lima, F.M. de; Martinelli, A.M.; Bezerra, U.T.; Mello, D.M.A. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil); Araujo, R.G.S. [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    2004-07-01

    Portland cement is by far the most important binding material used in oil well cementing. The cement sheath is responsible for both the mechanical stability of the wellbore and zonal isolation. During primary cementing and the production lifespan of the well, the cement sheath is exposed to adverse thermo-mechanical conditions, which may crack the intrinsically brittle cement material. Cracking affects the mechanical integrity of the sheath resulting in the contamination of oil or gas pay zones, as well as in the increase of producing costs related to the extraction of pebble and water. This scenario is especially encountered in wells containing heavy oils, typical of the Northeastern region of Brazil. The objective of the present study was to improve the fracture toughness of hardened Special Portland Cement slurries by the addition of aqueous polyurethane to Portland-based slurries used in primary cementing, plug backs and squeeze operations, improving environmental and economical impacts. The results revealed that the addition of polyurethane increased the viscosity of the slurry but still within the limits established by oil well cement guidelines. No significant increase was observed in the compressive strength of the cement. However, the addition of polyurethane improved the toughness of the cement increasing its ability to withstand thermo-mechanical cycles typical of heavy oil recovery. In addition, significant reduction in permeability was observed as the contents of polyurethane increased, contributing to the reduction in set time and gas migration through the cement sheath. (author)

  19. Adiçăo de biopolímeros em pastas de cimento para utilizaçăo em poços de petróleo /

    OpenAIRE

    Garcia, Marcela Ines

    2007-01-01

    Orientador: Kleber Franke Portella Co-orientadora: Helena Maria Wilhelm Dissertaçao (mestrado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduaçao em Engenharia - PIPE. Defesa: Curitiba, 2007 Inclui bibliografia Área de concentraçao: Engenharia e cięncias de materiais

  20. In vitro evaluation of marginal microleakage of class II bonded amalgam restorations using a dentin adhesive and a glass ionomer cement Avaliação in vitro da microinfiltração marginal em restaurações de amálgama tipo classe II usando adesivo dentinário e cimento de ionômero de vidro

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    Edmêr Silvestre PEREIRA JÚNIOR

    1999-04-01

    Full Text Available The purpose of this study was to evaluate in vitro the effectiveness of the dentin bonding system All Bond 2 associated with Resinomer (Bisco, and of Vitrebond (3M glass ionomer cement fresh-mixed, both used in the bonded amalgam technique, to prevent short-term microleakage in class II cavities restored with Dispersalloy (Dentsply, an admixed alloy. The control group utilized the Copalite (Cooley & Cooley varnish. Forty five sound human extracted premolars were used. Class II cavity preparations were made on the mesial and distal surfaces of non-carious teeth, with the gingival margins wall established 1mm under the cementum enamel junction. The specimens were divided randomly into three groups with thirty cavities in each group. The teeth were stored in distilled water for 24 hours and were thermocyled through 500 cycles in distilled water between 5°C and 55°C with a dwell time of 15 seconds. The apices and roots of the teeth were sealed. They were placed in a 37°C bath of 0.5% basic fuchsin dye for 24 hours. The teeth were washed in tap water for 24 hours and cut. The microleakage scores per restoration were averaged and three values of various test groups were subjected to the Kruskal-Wallis and Dunn test at a significance level of p O objetivo deste estudo foi avaliar in vitro a efetividade na prevenção da microinfiltração do sistema adesivo All Bond 2 associado ao Resinomer (Bisco, e do cimento de ionômero de vidro Vitrebond (3M, sem polimerização, em amálgama adesivo classe II, restauradas com Dispersalloy (Dentsply. No grupo controle utilizou-se o verniz cavitário Copalite (Cooley & Cooley. Para tanto, 45 pré-molares humanos íntegros e extraídos, com finalidade ortodôntica, receberam cavidades classe II, sendo uma na face mesial e outra na face distal de cada dente, com a parede cervical localizada a 1mm além da junção cemento-esmalte, sendo 30 cavidades em cada grupo. Após as restaurações os dentes foram estocados

  1. In vivo evaluation of the sealing ability of two endodontic sealers in root canals exposed to the oral environment for 45 and 90 days Avaliação, in vivo, da capacidade de selamento de dois cimentos endodônticos em canais radiculares expostos ao meio bucal por 45 e 90 dias

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    Patrícia Maria Poli Kopper

    2006-01-01

    Full Text Available This in vivo study evaluated the sealing ability of a resin-based sealer (AH Plus and a zinc oxide-eugenol sealer (Endofill in dogs' teeth, exposed to the oral environment for 45 and 90 days. Forty eight lower incisors from 8 dogs were endodonticaly treated. A stratified randomization determined the sealer use in each root canal. All canals were filled using the lateral condensation technique. The excess filling material at the cervical portion of the root canal was sectioned, leaving a 10-mm obturation length inside the canal. Teeth were provisionally sealed with glass ionomer cement for 24 h and the canals were exposed to the oral environment for either 45 or 90 days. Therefore, the experimental groups were as follows: A45- AH Plus for 45 days; A90- AH Plus for 90 days; E45- Endofill for 45 days; and E90- Endofill for 90 days (n=12. After the experimental period, the dogs were killed and the lower jaw was removed. The incisors were extracted and the roots were covered with two coats of nail varnish. The teeth were immersed in India ink for 96 h and submitted to diaphanization. Dye leakage (in mm was measured using stereomicroscopy (10x magnification. The results were statistically analyzed using two-way ANOVA and Tukey test for multiple comparisons (á = 0.05. Group E90 (2.03±0.94 showed significantly higher mean leakage value than all other groups (pEste estudo in vivo avaliou a capacidade de selamento de um cimento endodôntico resinoso (AH Plus e um a base de óxido de zinco eugenol (Endofill, em dentes de cães, expostos ao meio bucal, por 45 e 90 dias. Foi realizado o tratamento endodôntico de 48 incisivos inferiores de 8 cães. Uma randomização estratificada determinou o tipo de cimento a ser usado em cada canal que foram tratados pela técnica de condensação lateral. Após a obturação, o excesso de material obturador, na porção cervical do canal radicular foi seccionado, restando o comprimento de 10 mm no interior do canal

  2. Fixação de fraturas ilíacas em cães com parafusos, fios de aço e cimento ósseo de polimetilmetacrilato Canine iliac fracture fixation with screws, orthopedic wire and polymethylmethacrylate bone cement

    Directory of Open Access Journals (Sweden)

    Claudio Roehsig

    2008-09-01

    Full Text Available O presente trabalho teve como objetivo verificar a recuperação da locomoção e o tempo para cicatrização óssea de fraturas ilíacas fixadas com parafusos, fios de aço e cimento ósseo de polimetilmetacrilato. Dezesseis cães de ambos os sexos, com peso de 1,8 a 16kg e idade entre sete meses e 11 anos, foram submetidos à osteossíntese da fratura de ílio, provocadas por acidente automobilístico. Em dois animais, realizou-se osteossíntese bilateral, totalizando 18 ossos ilíacos operados. A abordagem ao ílio foi lateral e quando necessária estendida caudalmente através da osteotomia do trocanter maior. As fraturas foram reduzidas e, em cada segmento ósseo, foram implantados dois a três parafusos e banda de tensão com fio de aço entre os parafusos adjacentes à linha de fratura. Sobre esses implantes aplicou-se cimento ósseo misturado com cefazolina sódica e após o endurecimento prosseguiu-se com a síntese dos tecidos moles com suturas rotineiramente utilizadas na clinica cirúrgica. No período pós-operatório, foram realizadas avaliações até 90 dias após a osteossíntese e observou-se locomoção apropriada em 15 animais. Avaliações radiográficas demonstraram sinais de completa consolidação óssea entre 60 e 90 dias. Falha da estabilização ocorreu em dois casos, obrigando a reintervenção cirúrgica em um deles. A partir dos resultados obtidos, é possível concluir que, em cães com até 16kg de peso, a fixação de fraturas ilíacas utilizando parafusos cimentados com PMMA constitui uma eficiente técnica, que proporciona adequada estabilidade, precoce recuperação funcional e cicatrização óssea.The present study aimed to verify the time for locomotion recovery and bone healing in canine iliac fractures fixated with screws, orthopedic wires and methylmetacrylate bone cement. Sixteen dogs from both genders accidentally hit by a car and showing iliac fractures were included. Dogs aged from 7 months to 11

  3. Avaliação da dureza superficial de cimentos resinosos utilizados na cimentação de pinos de fibra de vidro

    OpenAIRE

    Fernanda Zander Grande

    2006-01-01

    O objetivo deste trabalho foi analisar a interação de dois tipos de ativação de sistemas adesivos (fotoativável e ativação dual) e dois tipos de ativação de cimentos resinosos (ativação química e ativação dual) nos valores de microdureza Vickers dos cimentos em diferentes profundidades de polimerização e diferentes proximidades com o sistema adesivo utilizado. Foram utilizados 50 incisivos bovinos inferiores que tiveram suas coroas seccionadas transversalmente para a utilização...

  4. Influencia de sistemas adesivos sobre a resistencia a tração da união amalgama de prata-cimento de ionomero de vidro

    OpenAIRE

    Mauro Antonio de Arruda Nobilo

    1993-01-01

    Resumo: O objetivo deste estudo foi avaliar in vitro a resistência à tração da união amálgama de prata-cimento de ionômero de vidro, sob a influência de sistemas adesivos. Foram confeccionados corpos de prova com diferentes dimensões para cada material em matrizes cilindricas de Teflon, possuindo na região central uma cavidade de formato tronco-cônico retentivo. A base ionomérica foi confeccionada com cimento de ionômero de vidro VID ION F. Após o acondiciomento do sistema adesivo e perfeita ...

  5. "Uso do cimento de ionômero de vidro na prática odontológica."

    OpenAIRE

    Vania Aparecida Oliveira Queiroz

    2003-01-01

    O objetivo deste trabalho foi verificar a utilização dos cimentos de ionômero de vidro na clínica odontológica e associá-la ao perfil do cirurgião-dentista. Foram enviados 340 questionários a todos os membros da Associação Brasileira de Odontologia que residiam em Ponta Grossa, estado do Paraná. Os dados requisitados incluíram: ano de formatura, grau de formação, meios de informação utilizados, tipos de cimentos de ionômero de vidro empregados, para quais indicações e em quais pacientes. No t...

  6. Desempenho de telhas de escória de alto forno e fibras vegetais em protótipos de galpões Performance of tiles composed of blast furnace slag and vegetable fiber in prototype barns

    Directory of Open Access Journals (Sweden)

    Maristela N. da Conceição

    2008-10-01

    Full Text Available Busca-se, em todo o mundo, a substituição do cimento amianto por alternativas seguras para o ambiente e para a saúde do trabalhador, além de econômicas, razão por que o uso de fibras vegetais como aglomerado em países tropicais onde estes resíduos são abundantes, tem-se mostrado bastante viável. No presente experimento foram comparadas telhas de cimento amianto pintadas com tinta reflexiva, telhas cerâmicas e telhas compostas de uma matriz à base de cimento Portland CPII 32Z (ABNT NBR-5735, escória de alto-forno (EAF e sílica ativa, reforçadas com fibras de polpa celulósica de sisal (Agave sisalana. Utilizaram-se protótipos de galpões avícolas nos quais o calor produzido pelas aves foi simulado por lâmpadas incandescentes. Para caracterização do ambiente térmico lançou-se mão dos índices de conforto: ITU (índice de temperatura e umidade, ITGU (índice de temperatura de globo e umidade, CTR (carga térmica radiante e entalpia (H em que os resultados demonstraram que as telhas compostas apresentaram comportamento térmico semelhante ao das telhas cerâmicas, podendo ser utilizadas em substituição às telhas de cimento amianto.The substitution of cement asbestos by safer and equally economical alternatives has being searched for throughout the world. The usage of vegetal staple fiber as agglomerate in tropical countries where these residues are abundant has shown it self to be viable. In this study, roofing tiles fabricated with cement base Portland CPII 32Z (ABNT NBR-5735, blast furnace slag (EAF, active silica reinforced with cellulose pulp staple fibers of sisal (Agave sisalana were compared with cement asbestos roofing tiles with white paint and ceramic roofing tiles. Prototypes of poultry facilities were used and lamps simulated the heat produced by the birds. Indices ITU, ITGU, CTR and entalpy (H were employed for the characterization of the thermal atmospheric comfort and the results showed that the alternative

  7. Resistência à infiltração de glicose de quatro cimentos reparadores

    OpenAIRE

    2010-01-01

    O presente estudo teve como objetivo comparar a qualidade do selamento promovido por 3 cimentos reparadores endodônticos: Ceramicrete, iRoot-BP Plus e BioAggregate, com o ProRoot MTA branco, utilizando o modelo de infiltração de glicose sob pressão. 64 incisivos centrais superiores, recém-extraídos e sem tratamento endodôntico foram selecionados. A instrumentação do canal radicular foi realizada em todos os dentes com brocas Gates-Glidden e limas K-Flexofile (Dentsply Maillefer, Ballaigues Su...

  8. Cola à base de PVA e argamassa de solo-cimento como alternativas para o assentamento de alvenaria de tijolos maciços de solo-cimento PVA glue and cement soil mortars as alternatives for laying cement soil blocks masonry

    Directory of Open Access Journals (Sweden)

    Gisleiva C. dos S. Ferreira

    2011-04-01

    Full Text Available Neste trabalho, foi analisada a viabilidade de emprego de cola à base de PVA e argamassa de solo-cimento no assentamento de paredes de alvenaria de tijolos maciços de solo-cimento, em substituição à argamassa usual (cimento, cal e areia. Pequenos prismas, executados com quatro tijolos maciços de solo-cimento e assentados com as argamassas e a cola de PVA, foram ensaiados à compressão e à flexão. Os resultados dos ensaios dos prismas executados com a argamassa de assentamento usual foram tomados como padrão esperado de comportamento para os outros prismas executados com argamassa de solo-cimento e com cola de PVA. Os resultados obtidos nos ensaios dos prismas indicaram que tanto cola à base de PVA quanto argamassa de solo-cimento podem ser empregadas, satisfatoriamente, no assentamento de painéis de alvenaria de tijolos maciços de solo-cimento.This study presents the results of an experimental investigation in characterizing the properties of cement soil block masonry using cement-soil mortars and PVA glue. The study deals with the scantily explored area of tensile bond strength of soil-cement block masonry using cement-soil mortars and PVA glue. Flexural bond strength of masonry has been determined by testing stack-bonded prisms using a bond wrench test set-up. The study clearly demonstrates the superiority of cement-soil mortar over other conventional mortar such as cement mortar. The results of this study can be conveniently used to select a proportion for cement-soil mortar or PVA glue proportion for cement soil block masonry structures.

  9. El cemento portland blanco

    Directory of Open Access Journals (Sweden)

    Rimathé, W.

    1959-12-01

    Full Text Available Not availableEn un artículo precedente, el autor expuso los resultados de los ensayos hechos oficialmente con el cemento CBR extrablanco. El cemento blanco está químicamente emparentado con el cemento portland. En una tabla da el autor la composición química del cemento blanco producido en diferentes paises, en comparación con la del cemento portland.

  10. Propriedades microestruturais de argamassas de cimento Portland com adições minerais e poliméricas utilizadas na fixação de porcelanato Study of the influence of additions on the adherence between polymer-modified mortars and porcelain stoneware tiles

    Directory of Open Access Journals (Sweden)

    A. E. F. S. Almeida

    2006-09-01

    Full Text Available Apesar de suas excelentes características técnicas e estéticas, a aplicação do porcelanato requer especial atenção quanto aos procedimentos de execução, devido ser um material diferente das cerâmicas convencionais, principalmente quando aplicados às fachadas as quais estão sujeitas a diversos agentes capazes de danificar os revestimentos cerâmicos. Podem ser encontrados na literatura trabalhos científicos que estudam as propriedades das argamassas colantes para assentamento de materiais cerâmicos com absorção de água superior a 3%, o que não é observado para os porcelanatos que apresentam absorção de água próxima de zero. Essa é a principal causa da perda ou falta de aderência entre o tardoz da placa de porcelanato e a argamassa, pois não permite o mecanismo de aderência mecânica existente nas cerâmicas porosas. O presente trabalho apresenta algumas propriedades de argamassas com adições de polímero e sílica ativa para a fixação de porcelanato, contribuindo para solucionar os problemas encontrados quanto a falta de aderência. A adição combinada de polímero e sílica ativa às argamassas resulta em excelentes propriedades, ideais para reparos e revestimentos que exigem elevado desempenho, o que viabiliza seu estudo visando a fixação de porcelanato. Os procedimentos experimentais para a determinação da aderência seguiram as prescrições constantes na NBR 14084 - Argamassa colante industrializada para assentamento de cerâmica - Determinação da resistência de aderência. Os resultados obtidos evidenciaram a importância da continuidade do estudo, além da aplicabilidade das argamassas especiais quanto a fixação do revestimento cerâmico em estudo. São apresentadas micrografias das amostras fraturadas das argamassas obtidas por microscopia eletrônica de varredura, assim como o diâmetro médio dos poros das argamassas obtido por porosimetria por intrusão de mercúrio.Despite the excellent

  11. Development of electro fused aggregates for use in refractories for the burning zone of cement kilns; Desenvolvimento de agregados eletrofundidos para utilizacao em refratarios para a zona de queima de fornos de cimento

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Luis Leonardo Horne Curimbaba

    2006-07-01

    Electro fused aggregates are largely used in refractory production due to the better performance reached when they are employed. In this work electro fused aggregates were designed for application in refractories for the burning zone of cement kilns. Initially reaction evaluation was conducted aiming the identification of the most prone refractory systems when single refractory phases react with Portland cement phases at high temperatures. In the next step, raw materials of the best refractory systems were electro fused to generate different aggregate compositions. The electro fused aggregates properties were evaluated and the classified ones were used to produce refractory bricks for the burning zone of cement kilns. General characteristics of these bricks were measured and compared with a standard magnesia-spinel refractory. Aggregates of the system Mg O - TiO{sub 2} - Ca O, more specifically aggregates belonged to the compatibility triangle Mg O - Mg{sub 2}TiO{sub 4} - CaTiO{sub 3}, showed suitable characteristics for development of refractories for the burning zone cement kilns. (author)

  12. Alpha-tricalcium phosphate cement in the reconstruction of bone defects in rats Cimento de alfa-tricálcio-fosfato na reconstrução de defeitos ósseos em ratos

    Directory of Open Access Journals (Sweden)

    João Gabriel Souza Pinto

    2011-04-01

    Full Text Available PURPOSE: To evaluate the ability of a mixture of α-TCP and autogenous bone (AB vs. α-TCP alone and AB alone to promote new bone formation and tissue repair in bone defects. METHODS: Bone defects surgically created in 15 male Wistar rats were divided into four groups: Group I (AB, Group II (α-TCP, Group III (α-TCP+AB assessed by light microscopy, and Group IV (α-TCP+AB assessed by scanning electron microscopy. Bone repair findings were assessed at 30, 60, and 120 days postoperatively. RESULTS: The histological findings obtained in Groups I (p=0.459, II (p=0.368, and III (p=0.459 and at 30 days (p=0.717, 60 days (p=0.717, and 120 days (p=0.779 did not show statistically significant differences. Scanning electron microscopy revealed direct contact between the α-TCP+AB implant and the bone tissue at 120 days. CONCLUSION: The α-TCP implant is effective alternative bone substitutes for the treatment of critical size bone defects.OBJETIVO: Avaliar a capacidade da mistura de α-TCP e osso autógeno (OA Vs somente α-TCP e somente OA em promover a neoformação óssea e reparo tecidual em defeitos ósseos. MÉTODOS: Foram criados cirurgicamente defeitos ósseos em 15 ratos Wistar machos, distribuídos em quatro grupos: Grupo I (OA, Grupo II (α-TCP, Grupo III (α-TCP + OA avaliado por microscopia de luz e Grupo IV (α-TCP + OA avaliado por microscopia eletrônica de varredura. Os resultados da reparação óssea foram avaliados em 30, 60 e 120 dias. RESULTADOS:os achados histológicos obtidos nos grupos I (p = 0,459, II (p = 0,368 e III (p = 0,459 e aos 30 dias (p = 0,717, 60 dias (p = 0,717, e 120 dias (p = 0,779 não apresentaram diferenças estatisticamente significativas. A análise por microscopia eletrônica de varredura revelou contacto direto entre o implante de α-TCP + AO e o tecido ósseo aos 120 dias. CONCLUSÃO: O implante de α-TCP é alternativa eficaz como substitutos ósseos para o tratamento de defeitos ósseos de tamanho crítico.

  13. Grau de infiltração marginal de duas técnicas restauradoras com cimento de ionômero de vidro em molares decíduos: estudo comparativo " in vitro Microleakage between two filling restorative techniques using glass ionomer cement in primary molars: comparative "in vitro " study

    Directory of Open Access Journals (Sweden)

    Paulo Floriani Kramer

    2003-06-01

    Full Text Available A técnica do condicionamento ácido e o desenvolvimento e aprimoramento de novos materiais restauradores com características adesivas têm levado a mudanças importantes nas concepções e nos princípios da dentística operatória e restauradora. O objetivo deste estudo foi avaliar a microinfiltração marginal em cavidades proximais de molares decíduos restaurados com cimento de ionômero de vidro modificado por resina (Vitremer, 3M comparando duas diferentes técnicas: a técnica convencional (conforme recomendações do fabricante e a técnica de hibridização (ácido fosfórico-37% e sistema adesivo Scotchbond Multi-Uso, 3M . Foram utilizados 20 molares decíduos hígidos, onde foram preparadas cavidades proximais. A amostra foi dividida aleatoriamente em 2 grupos. No grupo 1 foi utilizado a técnica convencional e no grupo 2 a técnica com condicionamento ácido e aplicação de sistema adesivo. Os dentes foram submetidos ao processo de ciclagem térmica, impermeabilizados, mantendo uma área de 2mm² na margem cervical da restauração e imersos em solução de azul de metileno a 0,5%, por 72 horas. A seguir, foram seccionados e avaliados por um único examinador, que estabeleceu o grau de microinfiltração. Os dados obtidos revelaram que as duas técnicas utilizadas apresentaram microinfiltração marginal em diferentes graus, e que não houve diferença estatisticamente significante entre elas.This study evaluate the marginal microleakage in deciduous molars cavities restored with ionomer cement modified by resin (Vitremer, 3 M comparing two different techniques: the conventional (according to manufacturer instructions and with the hybridization technique (acid phosphoric 37% and adhesive system Scotchbond Multi Pourpose , 3M. Proximal cavities were prepared in 20 sound deciduous molars, right after extraction. The samples were randomly divided in two groups. Group 1 consisted in teeth prepared with the conventional technique and

  14. Estudo das características químicas e físicas da cinza da casca da castanha de caju para uso em materiais cimentícios = A study of the chemical and physical properties of cashew nut shell ash for use in cement materials

    Directory of Open Access Journals (Sweden)

    Sofia Araujo Lima

    2010-10-01

    Full Text Available As cinzas ocupam lugar de destaque dentre os resíduos agroindustriais por resultarem de processos de geração de energia. Sabe-se que muitas dessas cinzas possuem reatividade pozolânica, podendo ser utilizadas como adição mineral em matrizes de cimento Portland. O presente estudo tem como objetivo investigar as características físicas equímicas da cinza da casca da castanha de caju (CCCC, por meio dos seguintes ensaios: análise química, massa unitária, massa específica, extratos lixiviado e solubilizado, difratometria de raios X (DrX, superfície específica (BET e análise da pozolanicidade com o cimento Portland e com a cal. O conjunto de análises deste trabalho indica a restrição ao uso da CCCC em matrizes cimentícias em função da baixa reatividade com o hidróxido de cálcio (CH e dos altos teores de álcalis, dos metais pesados e do fenol detectados nessa cinza.Ash occupies a prominent place among agro-industrial wastes, as it is derived from energy generation processes. Several types of ash havepozzolanic reactivity, and might be used as replacement material for cement, resulting in less energy waste and lower cost. This work aimed to investigate the physical and chemical properties of the cashew nut shell ash (CNSA, by performing the following measurementtests: chemical analysis, bulk density, specific mass, leaching and solubilization process, Xray diffraction (XrD, specific surface area (BET and pozzolanicity analysis with cement and lime. The results indicate a low reactivity of CNSA and the presence of heavy metals,alkalis and phenol.

  15. Lodging Update: Portland, Maine

    Directory of Open Access Journals (Sweden)

    Rachel J. Roginsky

    2013-01-01

    Full Text Available Each quarter, Pinnacle Advisory Group prepares an analysis of the New England lodging industry, which provides a regional summary and then focuses in depth on a particular market. These reviews look at recent and proposed supply changes, factors affecting demand and growth rates, and the effects of interactions between such supply and demand trends. In this issue, the authors summarize regional performance for 2012, offer projections for 2013, and spotlight the lodging market in Portland, Maine.

  16. Scrap tire rubber as modifier of asphalt cement for use in road paving Borracha de pneus como modificador de cimentos asfálticos para uso em obras de pavimentação

    Directory of Open Access Journals (Sweden)

    Sandra Oda

    2001-05-01

    Full Text Available This work presents the results of a research on the technical feasibility of the use of asphalt-rubber binder by the asphalt paving industry. In Brazil more than 30 million tires a year are disposed of, mostly in inadequate sites, causing serious health and environmental problems. The effects of the main factors (rubber content, rubber particle size, temperature of mixture, reaction time on the behavior of asphalt-rubber binders are evaluated by traditional and Superpave Method tests, the latter based on certain fundamental properties directly related to field performance. Results of the statistical analysis of the factorial design of laboratory experiments show the most significant effect of rubber contents, or rather, that asphalt-rubber binder may increase the resistance against permanent deformation and fatigue crackingEste trabalho apresenta estudo sobre a incorporação de borracha de pneus em ligantes asfálticos utilizados em obras de pavimentação. Trata-se de uma alternativa para solucionar um grave problema ambiental, pois no Brasil, anualmente, são descartados mais de 30 milhões de pneus, dos quais a maior parte é disposta em locais inadequados, servindo para a procriação de vetores de doenças e representando risco de contaminação do meio-ambiente. Os efeitos dos principais fatores que condicionam o comportamento do ligante asfalto-borracha (teor e granulometria da borracha, temperatura de mistura, tempo de reação são avaliados através de ensaios tradicionais de caracterização de ligantes asfálticos e ensaios do Método Superpave, diretamente relacionadas ao desempenho dos pavimentos no campo. Os resultados da análise estatística evidenciam o efeito preponderante do teor de borracha e, principalmente, que o ligante asfalto-borracha pode aumentar a resistência ao acúmulo de deformação permanente e ao aparecimento de trincas por fadiga do revestimento

  17. INFILTRAÇÃO MARGINAL DE CIMENTOS IONOMÉRICOS MODIFICADOS POR RESINA

    Directory of Open Access Journals (Sweden)

    CARRARA Carlos Eduardo

    1997-01-01

    Full Text Available Comparou-se a infiltração marginal de dois cimentos restauradores que liberam flúor, o Vitremer/3M e o Variglass/Caulk Dentsply. Cavidades classe II foram confeccionadas nas faces mesiais e distais de pré-molares extraídos. Cada dente recebeu uma restauração de cada material. Procedeu-se, então, a termociclagem em solução de fucsina básica a 0,5%. Nenhum material foi capaz de evitar a infiltração marginal, porém, esta foi menor nas restaurações de Vitremer/3M (p<0,01.

  18. Atividade pozolânica dos resíduos do beneficiamento do caulim para uso em argamassas para alvenaria Pozolanic activity of kaolin processing residues for use in masonry mortars

    Directory of Open Access Journals (Sweden)

    Romualdo R. Menezes

    2009-12-01

    Full Text Available A indústria do beneficiamento do caulim gera enorme quantidade de resíduos, descartados indiscriminadamente no meio ambiente; assim, este trabalho tem por objetivo analisar a viabilidade técnica e a atividade pozolânica dos resíduos do beneficiamento do caulim para a produção de argamassas. Os resíduos foram caracterizados através da determinação de sua distribuição granulométrica e composição química, difração de raios X e análise térmica diferencial e gravimétrica; em seguida, determinou-se o índice de atividade pozolânica dos resíduos de caulim com a cal e o cimento Portland. Argamassas de cimento:cal:areia foram preparadas e o resíduo, na condição natural e após queima a 600 °C por 2 h, substituiu parcialmente o cimento nas proporções de 5, 10, 15 e 20% em massa. Corpos-de-prova foram moldados e determinada sua resistência a compressão simples. Conclui-se, com base nos resultados, que os resíduos são constituídos de caulinita, mica e quartzo e que a utilização do resíduo calcinado aumenta a resistência das argamassas após 28 dias de cura em até 150%.The kaolin processing industry generates large amounts of waste, which is indiscriminately dumped in open-air sites. This work evaluates the technical suitability and pozolanic activity of kaolin processing wastes for the production of mortars. The wastes were characterized by particle size distribution and chemical composition determination, X-ray diffraction and thermal differential and gravimetric analyses. The pozolanic activity index was determined using lime and Portland cement. Cement:lime:sand mortars were formulated and the kaolin wastes replaced cement by 5, 10, 15 and 20% on weight basis. The kaolin wastes were used in their natural condition and after thermal treatment at 600 °C for 2 h. Test specimens were produced and their compression strength determined. The results indicated that the waste consists of quartz, kaolinite and mica, and

  19. Mensuração digital da radiopacidade de diferentes cimentos obturadores resinosos e de base zinco-enólica = Digital radiopacity measurement of different resin- and zinc oxide-based root canal sealers

    Directory of Open Access Journals (Sweden)

    Bodanezi, Augusto

    2010-01-01

    Full Text Available Objetivo: Avaliar a radiopacidade produzida por sete cimentos comercialmente disponíveis (AH Plus, Epiphany, Sealapex, Acroseal, Sealer 26, Endomethasone and Endofill e um em estágio experimental (MBP. Metodologia: Depois de homogeneizados os materiais, o teste de radiopacidade foi executado conforme a especificação no 57 da ANSI/ADA. Radiografou-se os espécimes junto a uma escala de Alumínio e as imagens resultantes foram digitalizadas. As densidades radiográficas expressas em milímetros de Alumínio (mm Al foram comparadas por meio da análise de variância e teste de Tukey (a=0. 05. Resultados: Os cimentos AH Plus (10 mm Al e Epiphany (9 mm Al apresentaram as maiores radiopacidades seguidos pelo Sealapex (8 mm Al, Endofill (7 mm Al, Endométhasone (7 mm Al, MBP (7 mm Al e Sealer 26 (6 mm Al. Acroseal (5 mm Al mostrou a menor radiopacidade entre os cimentos testados (P<0. 05. Conclusão: Concluiu-se que as diferentes radiopacidades dos cimentos testados estão acima do nível mínimo recomendado pela especificação nº 57 da ANSI/ADA

  20. Resistência de união entre liga de níquel-cromo e cimentos resinosos

    Directory of Open Access Journals (Sweden)

    FRANÇA Rodrigo de Oliveira

    1998-01-01

    Full Text Available O objetivo do trabalho foi a determinação da retentividade, por ensaio de tração, entre uma liga de níquel-cromo e cimentos resinosos (Comspan, Panavia Ex e All-Bond C & B, com quatro tratamentos superficiais (liso, microjateado, ataque eletrolítico e silicoater e armazenagem por 3 e 30 dias em solução de NaCl a 0,9%, a 37° C e termociclagem intercalada na segunda (a 5 e 55° C, por 1 minuto em cada banho, perfazendo 600 ciclos. Os corpos de prova eram discos, providos de alça fixadora entre si dois a dois. Os resultados permitiram concluir que: superfícies lisas conduzem a baixíssimas retentividades e tratadas com silicoater a altíssimos valores, com qualquer cimento e condição de armazenagem; Panavia Ex com superfícies microjateadas também conduz a altas retentividades; a maior retentividade foi obtida pela combinação silicoater/All-Bond C&B.

  1. Avaliação da influência da solução de irrigação na resistência adesiva de um cimento resinoso

    Directory of Open Access Journals (Sweden)

    Veridiana Camilotti

    Full Text Available INTRODUÇÃO: A contaminação do substrato dentinário pode interferir na qualidade de união entre materiais adesivos e o dente. OBJETIVO: Investigar a influência de diferentes soluções de irrigação na resistência de união de um cimento resinoso. MATERIAL E MÉTODO: Foram selecionadas 40 coroas dentais bovinas, divididas em quatro grupos: G0 = soro; G1 = clorexidina; G2 = EDTA; G3 = clorexidina 0,12%, após condicionamento ácido. Em seguida, foram confeccionados cilindros de cimento resinoso utilizando-se uma matriz de Tygon com diâmetro interno de 1 mm e 2 mm de altura. A fotoativação foi realizada por aparelho de luz LED com 900 mW/cm² por 40 segundos. Foram confeccionados quatro cilindros de cimento resinoso para cada coroa bovina, totalizando 40 corpos de prova de cimento resinoso para cada grupo avaliado. O teste de resistência adesiva por microcisalhamento foi realizado após 24 horas. Decorrido esse período, os cilindros de cimento resinoso foram testados em uma máquina universal de ensaios (EMIC. Os dados obtidos foram submetidos à análise estatística pelos testes ANOVA e Tukey (p = 0,001. RESULTADO: Não houve diferenças estatisticamente significativas entre os grupos estudados, com exceção para o G3, que apresentou de forma significativa os menores valores de resistência adesiva. CONCLUSÃO: As diferentes soluções irrigadoras utilizadas previamente ao condicionamento ácido na dentina não interferem na resistência de união por microcisalhamento.

  2. Il nuovo cimento, scritti scelti 1855-1944 in occasione del 150 anniversario della fondazione

    CERN Document Server

    Cifarelli, L; De Sanctis, E; Piragino, G; Ricci, R A

    2006-01-01

    In occasione dell'Anno Mondiale della Fisica (2005) la Società Italiana di Fisica ha ritenuto utle ripresentare in un volume celebrativo alcuni dei contributi pubblicati si Il Nuovo Cimento dalla sua fondazione nel 1855, quando apparve come riedizione della rivista Il Cimento.

  3. \\"Estudo da evolução da reação de presa do cimento de fosfato de zinco através de luz laser, aplicando a técnica óptica de speckle dinâmico\\"

    OpenAIRE

    2006-01-01

    A cimentação de próteses e/ou de outros elementos protéticos constituem-se em uma preocupação permanente, já que uma das grandes aplicações do cimento de fosfato de zinco é como agente cimentante. No entanto, a reação de presa do cimento de fosfato de zinco, assim como o tempo de sua presa final, não estão ainda completamente esclarecidos. O presente estudo visa analisar, microestruturalmente, a evolução da reação de presa do cimento de fosfato de zinco. Mais especificamente, buscou-se mensur...

  4. Influence of different kinds of rosins and hydrogenated resins on the setting time of Grossman cements Influência de diferentes tipos de breus e resinas hidrogenadas sobre o tempo de endurecimento dos cimentos do tipo Grossman

    Directory of Open Access Journals (Sweden)

    Manoel Damião SOUSA NETO

    1999-01-01

    Full Text Available In this study, the effect on the setting time by the addition of different kinds of rosin and hydrogenated resin on the Grossman cement powder was evaluated. The experiments were carried out following the American Dental Association’s specification number 57 for root canal sealers. For this analysis, different Grossman cement powders were prepared using different rosins (X, WW and WG and hydrogenated resins (Staybelite and Staybelite ester 10. The study of the physicochemical properties of the Grossman cements obtained the different kinds of rosins and hydrogenated resins interference on the cement’s setting time. The hydrogenated resin, having a higher pH, increased the setting time of the cement when compared to the X, WW and WG rosins.No presente estudo, analisou-se o efeito da adição de diferentes tipos de breus e resinas hidrogenadas ao pó do cimento de GROSSMAN sobre o tempo de endurecimento. Os experimentos foram realizados de acordo com a Especificação 57 para materiais obturadores de canais radiculares da American Dental Association (ADA. Para análise, foram aviados pós do cimento de GROSSMAN com diferentes tipos de breu (X, WW e WG e resinas hidrogenadas (Stabylite e Stabylite éster 10. Os estudos das propriedades físico-químicas dos cimentos tipo GROSSMAN obtidos de diferentes tipos de breus e resinas hidrogenadas interferem no tempo de endurecimento do cimento. A resina hidrogenada, obtida do processo de hidrogenação tem o pH mais alto, provocando um aumento do tempo de endurecimento do cimento em relação aos breus tipo X, WW e WG, que têm pH mais ácido.

  5. Penetração intratubular de cimentos endodônticos Intratubular penetration of root canal sealers

    Directory of Open Access Journals (Sweden)

    Gustavo de Deus

    2002-12-01

    Full Text Available Este estudo foi desenvolvido para avaliar a capacidade de penetração de diferentes cimentos endodônticos (Endo Fill, Sealapex, AH Plus e Pulp Canal Sealer nos túbulos dentinários em dentes devidamente modelados e obturados. Foram utilizados 72 incisivos centrais superiores, os quais foram instrumentados no sentido coroa-ápice pela técnica de forças balanceadas. O comprimento de trabalho foi estabelecido a 1 mm do ápice radicular. Durante a limpeza e modelagem, todos os dentes foram irrigados com 10 ml de hipoclorito de sódio a 5,25%. Os dentes foram divididos em 4 grupos, sendo 1 para cada tipo de cimento. Estes grupos foram então subdivididos em função do uso ou não de EDTA a 17% previamente à obturação dos canais radiculares, para a remoção da lama dentinária. Todos os dentes foram obturados pela técnica da onda de condensação com cone médio calibrado. Após obturação, as raízes foram seccionadas no sentido mésio-distal e foi escolhida a secção de melhor qualidade visual. Estas foram então analisadas em microscopia eletrônica de varredura (MEV, sendo o foco de observação sempre a interface dentina/material obturador. Após obtenção das imagens, mensurou-se os prolongamentos dos cimentos para o interior dos túbulos dentinários. O cimento de Rickert (Pulp Canal Sealer apresentou a maior capacidade de penetração nos túbulos dentinários, sendo os piores resultados apresentados pelo grupo em que se utilizou o Sealapex. Os resultados foram avaliados estatisticamente pelo teste de Spearman, o qual mostrou diferença estatisticamente significante (p The purpose of this study was to evaluate the capacity of penetration of four endodontic sealers (Endo Fill, Sealapex, AH Plus and Pulp Canal Sealer into dentinal tubules. Seventy-two extracted human maxillary anterior teeth were utilized in this study. The teeth were cleaned and shaped by means of the balanced-forces technique. The work length was established at 1

  6. 75 FR 44304 - Noise Exposure Map Notice, Portland International Airport, Portland, OR

    Science.gov (United States)

    2010-07-28

    ... Noise Exposure Map Notice, Portland International Airport, Portland, OR AGENCY: Federal Aviation... determination that the noise exposure maps submitted by Port of Portland for Portland International Airport under the provisions of 49 U.S.C. 47501 et seq. (Aviation Safety and Noise Abatement Act) and 14...

  7. Efeito da escovação simulada sobre cimentos de ionômero de vidro indicados para tratamento restaurador atraumático

    OpenAIRE

    2008-01-01

    O objetivo deste estudo foi mensurar a perda de massa e as alterações de rugosidade média superficial (Ra) de diferentes cimentos de ionômero de vidro indicados para tratamento restaurador atraumático tendo uma resina composta como material controle, após teste de escovação simulada. As características de superfície antes e após abrasão foram avaliadas em microscópio eletrônico de varredura (MEV). Os materiais testados foram: Vitro Fil LC ,Fuji IX , Vitro Molar , Maxxion R, e a resina compost...

  8. LIBERAÇÃO DE FLÚOR DE QUATRO CIMENTOS DE IONÔMERO DE VIDRO RESTAURADORES

    Directory of Open Access Journals (Sweden)

    TENUTA Lívia Maria Andaló

    1997-01-01

    Full Text Available A liberação de flúor de quatro cimentos de ionômero de vidro usados para restauração? Photac Fil (PF, Vitremer (VT, Fuji II LC (F2 e Fuji IX (F9 ? foi testada durante 14 dias. As leituras do flúor liberado para água deionizada foram realizadas por um eletrodo específico para esse íon, acoplado a um analisador de pH/íons. Os dados foram submetidos a análise de variância e teste de Tukey-Kramer. A quantidade de flúor liberada foi significantemente maior para o PF em relação aos outros materiais (PF > VT > F9 > F2, sendo que VT/F9 e F2/F9 não apresentaram diferença significante entre si (p < 0,05.

  9. Mineral trioxide aggregate as root canal filing material: comparative study of physical properties = MTA como cimento endodôntico: estudo comparativo de propriedades físicas

    Directory of Open Access Journals (Sweden)

    Silva, Wander José da

    2010-01-01

    Full Text Available Objetivo: Este estudo avaliou as propriedades físicas de dois cimentos MTA disponíveis comercialmente. Metodologia: A resistência a compressão (CS dos materiais avaliados foi realizada após 21 horas e 14 dias de imersão em água. A avaliação da radiopacidade (RD dos materiais foi mensurada em função de espessura de alumínio. Com relação à propriedade de tempo de presa (ST, tanto os tempos de presa inicial e final foram mensurados. A solubilidade foi calculada em função da percentagem de massa perdida após armazenamento em água. Os valores de pH foram mensurados em três diferentes tempos (inicial, 1 e 24 horas de armazenamento em água. Todos os testes foram realizados de acordo com a norma ISO 6876-2: 2001. Resultados: Ambos os materiais apresentaram valores de CS e pH em acordo com os valores da norma ISO. Os dois cimentos apresentaram RD superiores ao limite de 3 mm de alumínio. Ambos os materiais mostraram resultados de SB inferiores ao limite de 3%. ST e pH também estão de acordo com a norma ISO 6876-2: 2001. Adicionalmente foram avaliadas as superfícies dos materiais por MEV, e ambos apresentaram fases estruturais amorfas e cristalinas. Conclusão: Concluiu-se que ambos os materiais avaliados estão de acordo com as normas ISO, permitindo o seu uso como material de preenchimento de canais radiculares

  10. Avaliação da resistência de união de cimentos resinosos autoadesivos à zircônia e à dentina : Bond strenght evaluation of self-adhesive resin cements to dentin and zirconia

    OpenAIRE

    Tiago Monteiro Dias

    2016-01-01

    Resumo: O objetivo deste estudo foi avaliar a resistência de união de cimentos resinosos autoadesivos à zircônia e à dentina. As análises envolveram testes de amostras armazenadas após 24 horas e um ano em água destilada. No Estudo 1, testou-se o efeito da aplicação de primers (Z-Prime Plus e Zirconia Bond) na resistência de união de um cimento resinoso autoadesivo (RelyX Unicem 2) à superfícies de duas zircônias (Lava e Zircad). Nesse estudo, foram utilizadas 90 placas de zircônia (13mm x 5m...

  11. Cimentos endodônticos - selamento marginal apical imediato e após armazenamento de seis meses Endodontic cements - immediate apical sealing and after a six-month storage

    Directory of Open Access Journals (Sweden)

    Marcia Carneiro VALERA

    1998-10-01

    Full Text Available Este trabalho avaliou o selamento marginal apical de canais radiculares obturados com os cimentos endodônticos Sealapex, Apexit, Sealer 26 e Ketac Endo. Utilizaram-se 136 raízes, cujos canais radiculares, após o preparo biomecânico, foram obturados pela técnica da condensação lateral ativa com os cimentos em estudo. Metade das amostras, imediatamente após as obturações, foram imersas na solução de azul de metileno a 2% e a outra metade após 6 meses de armazenamento em plasma sangüíneo humano. Observou-se que os cimentos Sealapex e Sealer 26 apresentaram infiltrações médias estatisticamente iguais entre si e menores que as observadas para os demais cimentos (p The aim of this study was to verify the apical sealing of root canals obturated with Sealapex, Apexit, Sealer 26, and Ketac Endo cements. A hundred and thirty six dental roots were used for the experiment. After biomechanical preparation and lateral condensation filling, half of the roots were placed in human blood plasma storage medium for 6 months. The remaining samples were immediately placed in methylene blue, under a temporary vacuum, and after one week the amount of dye penetration measured. The stored samples were similarly treated after the 6-month storage period. Statistical analysis of the results revealed that the groups obturated with Sealapex and Sealer 26 showed the smallest amount of apical leakage (p < 0.05. There were significant differences in the amount of dye penetration after 6 months of storage (1.275 mm, when compared to the results found without storage (0.829 mm (p < 0.05.

  12. Avaliação da cimentação de pinos não metálicos na dentina intraradicular utilizando cimentos resinosos auto-adesivos

    OpenAIRE

    Roperto, Renato Cássio [UNESP

    2007-01-01

    Este estudo avaliou por meio da microtrção (µTBS) a adesão de pinos de fibra de vidro à cimentos auto-adesivos e convencionais. Oitenta dentes humanos recém-extraídos tratados endodonticamente foram divididos em 8 grupos (n=10). Dois diferentes tipos de pinos de fibra de vidor foram utilizados; pino de fibra de vidro silanizado (Reforpost/Angelus) (RA) e pinos flexíveis de fibra de vidro silanizados (EverStick/Sticktech) (EP). Esses foram cimentados em preparos protéticos no interior dos cond...

  13. Influencia da convergencia axial na adaptação e infiltração marginal de coroas totais fixadas com cimentos de fosfato de zinco, ionomero de vidro e resinoso

    OpenAIRE

    Claudio Figueiro

    1997-01-01

    Resumo: Este estudo avaliou a influência da convergência axial na adaptação e infiltração marginal de coroas totais fixadas com cimentos de fosfato de zinco (S.S. White), ionômero de vidro (Vitremer) e resinoso (Panavia 2 hx). Foram realizados preparos padronizados do tipo coroa total em 60 dentes molares recém extraídos, nos quais foram confeccionadas coroas metálicas em NiCr. Foram formados 12 grupos de acordo com: o agente cimentante utilizado, a convergência axial de 12° e de 16°, e a ut...

  14. Reciclagem secundária de rejeitos de porcelanas elétricas em estruturas de concreto: determinação do desempenho sob envelhecimento acelerado Secondary recycling of electrical insulator porcelain waste in Portland concrete structures: determination of the performance under accelerated aging

    Directory of Open Access Journals (Sweden)

    K. F. Portella

    2006-09-01

    Full Text Available O uso de entulhos, entre outros rejeitos industriais e domésticos, pela construção civil vem sendo prática comum em diversos países desenvolvidos, em razão tanto do aumento da quantidade de rejeitos e conseqüente esgotamento de espaços apropriados para seu destino final, quanto da constante e cada vez mais rigorosa fiscalização e punição pelos organismos ambientais competentes. Antecipando maneiras para solução desses problemas, propôs-se o estudo da reciclagem e imobilização de rejeitos de porcelanas elétricas em concreto, em substituição parcial aos agregados graúdos e miúdos naturais. A vantagem não foi total por causa do indício de reações expansivas que poderiam prejudicar determinadas aplicações. Assim, foi proposto o estudo das condições ideais de dosagem para mitigar os efeitos de tais reações pela presença de contaminantes destes rejeitos. Os resultados demonstraram a efetiva promoção de reações do tipo álcali-agregado, e que o uso de cimentos especiais poderá diminuir o efeito prejudicial dos subprodutos formados.The use of rubbish and other kinds of domestic and industrial wastes on civil construction has been a common practice in many developed countries, due either to the increase in the amount of waste and the resultant reduction of appropriate places to its final disposal, as well as to the severity and steadiness of environmental inspection organizations. In order to provide beforehand manners to solve or reduce these problems, study of recycling and co-disposal of waste from porcelain electrical insulators in concrete was proposed. Besides the occurrence of expansive reactions, which may be harmful to the stability of important structures, the overall results were encouraging. Some contaminants found in the three phases of porcelain contributed to the happening of alkali-aggregate reaction, which can easily inhibited by the using of special cements, such as a sulfur-resistant one.

  15. Chapa aglomerada de cimento-madeira de Hevea brasiliensis Müll. Arg. Cement-bonded particleboard of Hevea brasiliensis Müll. Arg.

    Directory of Open Access Journals (Sweden)

    Esmeralda Yoshico Arakaki Okino

    2004-06-01

    Full Text Available Chapas de partículas de cimento-madeira foram confeccionadas com a madeira de quatro clones de Hevea brasiliensis Müll. Arg. (seringueira: IAN 717, IAN 873, GT 711 e AVROS 1301. Confeccionaram-se as chapas na proporção de 1:4:1 (madeira:cimento:água por peso e nas dimensões de 450 x 450 x 13 mm e densidade nominal de 1,4 g/cm³, com a adição de 4% de cloreto de cálcio di-hidratado (CaCl2.2H2O como acelerador. Foram testadas partículas fervidas e não-fervidas dos quatro clones, totalizando oito tratamentos, sendo em cada um destes, com quatro repetições, avaliadas as propriedades mecânicas e físicas das chapas, segundo a norma ASTM D 1037 - 96a. De forma geral, os melhores resultados de propriedades físicas e mecânicas foram obtidos nas chapas com partículas do clone AVROS 1301. No teste de hidratação do cimento, a madeira de seringueira in natura foi classificada como de "inibição extrema", porém com a adição de CaCl2 o foi como de "baixa inibição". Essa madeira se mostrou tecnicamente viável à produção de chapas de cimento-madeira, independentemente do clone.Cement-bonded particleboards of rubberwood were manufactured with four clones of Hevea brasiliensis Müll. Arg. (rubberwood: IAN 717, IAN 873, GT 711 and AVROS 1301. Boards of 450 x 450 x 13 mm were manufactured in a ratio of 1:4:1 (wood/cement/water, weight basis, with 1.4 g/cm³ density and 4% calcium chloride dihydrated - CaCl2.2H2O as accelerator. The particles of four clones were tested in treated and untreated conditions, totaling eight treatments. In each treatment with four replicates, the physical and mechanical properties were evaluated according to ASTM D 1037 - 96a standard. Overall, the best mechanical and physical results were obtained with the cement-bonded particleboard made with particles from clone AVROS 1301. Rubberwood has shown to be "highly inhibitory" in the hydration test, however when CaCl2 was added the inhibition index decreased and

  16. Processamento de concretos refratários zero-cimento contendo alumina e microssílica Processing of zero-cement refractory castables containing alumina and microsilica

    Directory of Open Access Journals (Sweden)

    P. Bonadia Neto

    2000-03-01

    Full Text Available Os concretos auto-escoantes de reduzido teor de cimento aliam facilidade de aplicação a um bom desempenho em temperaturas elevadas. Estudos anteriores mostraram que a auto-escoabilidade e o empacotamento de partículas necessário para redução do teor de cimento são função da granulometria e do estado de dispersão da matriz do concreto. Bonadia e outros propuseram, então, uma metodologia de formulação de concretos baseada nestes dois conceitos, enfocando a otimização dos parâmetros granulométricos. Com a granulometria otimizada, Studart et al. geraram mapas de estabilidade, que fornecem as condições ideais para dispersão de uma matriz contendo apenas alumina. Com o auxílio destes mapas foi possível preparar concretos auto-escoantes isentos de cimento (zero-cimento. Devido à importância da microssílica como precursora da fase mulita no concreto, o objetivo deste trabalho foi gerar mapas de estabilidade para matrizes contendo alumina e microssílica. Os resultados mostraram uma correlação entre a fluidez dos concretos e as regiões de menor viscosidade e tensão de escoamento indicadas nos mapas.Low and ultra-low cement self-flow castables combine good high temperature performance and faster application rate. It has been shown that the castable self-flow ability and packing is a function of its particle size distribution and matrix rheological conditions. Bonadia and others proposed a castable formulation methodology based on these two concepts, focusing mainly the particle size distribution parameters. Stability maps, which predict the ideal matrix dispersion conditions, were generated by Studart et al. for aluminous castables in order to complete the proposed methodology. Such maps allowed the preparation of self-flow zero-cement (without any hydraulic binder castables compatible with industrial applications. Since microsilica is essential for mullite formation in castables, the main objective of this work is to generate

  17. Análise da porosidade, resistência mecânica e desgaste de cimentos de ionómero de vidro e resina composta

    OpenAIRE

    Rodrigues, Daniela Santos

    2014-01-01

    Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária Os cimentos de ionómero de vidro e as resinas compostas são os materiais restauradores diretos mais usados em medicina dentária. Os ionómeros de vidro apresentam libertação e absorção de iões de flúor com potencial efeito preventivo e remineralizante no processo de cárie dentária. No entanto, apresentam pobres propriedades físico‒mec...

  18. Evaluation of the antimicrobial activity of each component in Grossman’s sealer Avaliação da atividade antimicrobiana de cada um dos componentes do cimento de Grossman

    Directory of Open Access Journals (Sweden)

    Ricardo Novak Savioli

    2006-04-01

    Full Text Available The antimicrobial activity of Grossman’s sealer and its components was evaluated on 13 different strains using the double layer well-diffusion method. Results revealed that Grossman’s sealer presented antimicrobial activity against all the tested strains. Among the components of the cement, sodium tetraborate presented the greatest antimicrobial activity, both in type and diameter of the halo and ring of inhibition. Sealer powder, rosin, and eugenol presented similar activity, with no effect on P. aeruginosa and C. albicans. Among these, only eugenol had an effect on E. coli. Zinc oxide was only active against S. sobrinus and E. coli. Barium sulfate and bismuth subcarbonate did not show any antimicrobial effect.Os autores estudaram a atividade antimicrobiana do cimento de Grossman e de seus componentes sobre 13 diferentes cepas pelo método de difusão de poço em camada dupla. Os resultados revelaram que o cimento de Grossman apresentou atividade antimicrobiana contra todas as cepas utilizadas. Dos componentes do cimento, o tetraborato de sódio foi o que apresentou maior atividade antimicrobiana, tanto por tipo como por tamanho do halo e aro de inibição. O pó do cimento, o breu e o eugenol apresentaram atividades semelhantes, sendo que eles não tiveram ação sobre P. aeruginosa e C. albicans e, dos três componentes, somente o eugenol teve ação sobre E coli. O óxido de zinco somente teve ação sobre S. sobrinus e E. coli. O sulfato de bário e o subcarbonato de bismuto não tiveram nenhuma ação antimicrobiana.

  19. Influência do tratamento térmico de diferentes silanos na resistência de união entre um cimento resinoso e uma cerâmica feldspática

    OpenAIRE

    De Carvalho, Rodrigo Furtado [UNESP

    2011-01-01

    O presente estudo teve como objetivo, avaliar a influência do tratamento térmico de diferentes silanos na resistência de união entre um cimento resinoso e uma cerâmica feldspática. Foram confeccionados 72 blocos da cerâmica VITA VM7 (VITA Zahnfabrik, Bad Säckingen, Germany) e de resina composta microhíbrida (W3D MASTER – Wilcos do Brasil Ind. e Com. Ltda., RJ, Brasil) de dimensões aproximadas de 6,4 x 6,4 x 4,8mm. Os blocos foram divididos em 12 grupos (n=25) de forma ...

  20. Obtenção de concretos auto-escoantes zero-cimento a partir do controle reológico da matriz Production of self-flow zero-cement castables based on matrix rheological control

    Directory of Open Access Journals (Sweden)

    A. R. Studart

    2000-03-01

    Full Text Available Os concretos refratários auto-escoantes com reduzido teor de cimento têm se destacado pelo fato de associarem a facilidade de aplicação dos concretos de elevada fluidez, com o bom desempenho termomecânico dos refratários contendo baixo teor de CaO. Através do controle simultâneo da distribuição granulométrica e do estado de dispersão da matriz, é possível eliminar o cimento aluminoso (fonte de CaO e quaisquer outros ligantes hidráulicos do concreto, mantendo sua auto-escoabilidade. Os concretos obtidos, denominados zero-cimento, apresentam resistência mecânica a verde compatível com aplicações industriais e excelentes propriedades a altas temperaturas. Neste trabalho, são apresentadas as condições de dispersão da matriz necessárias para a obtenção dos concretos zero-cimento, após um ajuste granulométrico prévio. As faixas de pH e de teor de dispersante ideais para a otimização da reologia da matriz são apresentadas graficamente em um mapa de estabilidade, o qual mostrou-se uma ferramenta bastante útil para a formulação dos concretos auto-escoantes zero-cimento.Self-flow low-cement refractory castables have attracted much attention in the latest years because they combine the installation benefits of high-flowability castables with the good thermomechanical behaviour of low CaO-content refractories. By simultaneously controlling the castable particle size distribution and the matrix dispersion state, it becomes possible to eliminate the aluminous cement (CaO source or any other hydraulic binder in the castable, keeping its self-flow ability. Such castables, named self-flow zero-cement castables, exhibit pre-firing mechanical strength compatible with industrial applications and outstanding high temperature properties. The matrix dispersion conditions necessary to obtain these castables are presented in this work. The optimum range of pH and dispersant amount for the matrix rheological optimisation are

  1. Perbandingan Sifat Fisik Beton Yang Menggunakan Semen Portland Pozzolan Dan Semen Portland Tipe I

    OpenAIRE

    Yusnita, Heni

    2011-01-01

    The research about concrete by using the Portland pozzolan cement and Portland cement type I has been done with the variation of submersion time is 7, 14, 21, and 28 days. The test is done for physics of the concrete. The sample is made from the ingredients 1 cement : 2 sand : 3 pebble. The result of the researching shows that the used of the Portland pozzolan cement can raise the impact of the concrete as much as 9,15% from concrete which uses the Portland cement type I. Orther side for the ...

  2. Gravity Data for the Greater Portland Area

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The gravity station data (1,522 records) were compiled by the Portland State University. This data base was received in August 1990. Principal gravity parameters...

  3. Basalt waste added to Portland cement

    Directory of Open Access Journals (Sweden)

    Thiago Melanda Mendes

    2016-08-01

    Full Text Available Portland cement is widely used as a building material and more than 4.3 billion tons were produced in 2014, with increasing environmental impacts by this industry, mainly through CO2 emissions and consumption of non-removable raw materials. Several by-products have been used as raw materials or fuels to reduce environmental impacts. Basaltic waste collected by filters was employed as a mineral mixture to Portland cement and two fractions were tested. The compression strength of mortars was measured after 7 days and Scanning Electron Microscopy (SEM and Electron Diffraction Scattering (EDS were carried out on Portland cement paste with the basaltic residue. Gains in compression strength were observed for mixtures containing 2.5 wt.% of basaltic residue. Hydration products observed on surface of basaltic particles show the nucleation effect of mineral mixtures. Clinker substitution by mineral mixtures reduces CO2 emission per ton of Portland cement.

  4. EnviroAtlas - Portland, OR - Block Groups

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset is the base layer for the Portland, OR EnviroAtlas area. The block groups are from the US Census Bureau and are included/excluded based on...

  5. Ensaio mecânico da resistência ao impacto do cimento ósseo puro e associado a duas drogas anestésicas locais Mechanical essay of impact resistance of acrylic bone cement used singly or the cement in combination with two local anesthetic drugs

    Directory of Open Access Journals (Sweden)

    Vincenzo Giordano

    2007-07-01

    Full Text Available OBJETIVO: Investigar o comportamento mecânico da combinação de anestésico local e cimento ósseo in vitro. MÉTODOS: Foram comparados dois cimentos ortopédicos (Simplex® e Biomecânica® e duas drogas anestésicas locais de largo uso na clínica anestesiológica (lidocaína e bupivacaína. Os anestésicos utilizados estavam em pó. Elaboraram-se seis grupos de investigação, baseados na combinação ou não das drogas. Nos grupos em que o polímero foi combinado à medicação, a mistura consistiu de 40g de polimetilmetacrilato com 2g de anestésico local. Foram confeccionados 60 corpos de prova prismáticos, medindo 5 x 120 x 30mm (n = 30 e 5 x 60 x 30mm (n = 30. Os corpos de prova foram testados mecanicamente em máquina universal. Foram realizados ensaios mecânicos de resistência ao impacto direto. Foi realizada análise estatística para verificar o efeito do cimento (Simplex® e Biomecânica® e da medicação (lidocaína e bupivacaína na resistência do corpo de prova, com alfa = 5%. RESULTADOS: Observou-se que existe influência significativa da medicação na resistência do corpo de prova (p = 0,0001. Pelo teste de comparações múltiplas de Tukey, identificou-se, ao nível de 5%, que a mistura com bupivacaína apresentou resistência significativamente maior do que com a lidocaína e com o polímero puro. Não existe diferença significativa na resistência entre a lidocaína e o polímero puro. Existe influência significativa do cimento na resistência do corpo de prova (p = 0,015. Mostrou-se que o cimento Simplex® apresentou resistência significativamente maior do que o Biomecânica®. Existe influência significativa da interação cimento-medicação na resistência do corpo de prova (p = 0,035. A análise dos contrastes mostrou que o cimento Simplex® apresentou resistência significativamente maior do que o Biomecânica® apenas quando sem adição da medicação (p = 0,002. Não existe diferença significativa na

  6. Synthesis of pure Portland cement phases

    DEFF Research Database (Denmark)

    Wesselsky, Andreas; Jensen, Ole Mejlhede

    2009-01-01

    Pure phases commonly found in Portland cement clinkers are often used to test cement hydration behaviour in simplified experimental conditions. The synthesis of these phases is covered in this paper, starting with a description of phase relations and possible polymorphs of the four main phases...... in Portland cement, i.e. tricalcium silicate, dicalcium silicate, tricalcium aluminate and tetracalcium alumino ferrite. Details of the The process of solid state synthesis are is described in general including practical advice on equipment and techniques. Finally In addition, some exemplary mix compositions...

  7. Propriedades e bioatividade de um cimento endodôntico à base de aluminato de cálcio Properties and bioactivity of endodontic calcium aluminate cement

    Directory of Open Access Journals (Sweden)

    I. R. Oliveira

    2011-09-01

    Full Text Available Desde sua introdução na endodontia como um material retro-obturador e selador de defeitos da raiz dental, o agregado de trióxido mineral (MTA tem sido considerado como um material endodôntico revolucionário. Apesar disso, este material apresenta algumas propriedades limitantes, necessitando alterações em sua composição bem como desenvolvimento de novos materiais. Assim, o objetivo desse trabalho foi mostrar a influência de aditivos no desenvolvimento de um cimento endodôntico à base de cimento de aluminato de cálcio (ECAC. Além disso, foram avaliadas as propriedades do ECAC em comparação com o MTA, quando em contato com solução de fluido corporal simulado (SBF. Testes de manipulação e medidas de resistência à compressão, porosidade aparente, tempo de endurecimento, pH e condutividade iônica, foram realizados para os materiais MTA puro e ECAC contendo aditivos. Considerando as propriedades apresentadas pelo ECAC, este material alternativo pode ser indicado para múltiplas aplicações em endodontia.The mineral trioxide aggregate (MTA, a material primarily developed as a root-end filling has been extensively investigated as an innovative product for endodontic applications. However, changes in its formulation/composition involving its mineral aggregates and the development of alternatives of materials have been proposed in an attempt to overcome its negative physical-chemical characteristics. In this work, the influence of additives addition on the development of a novel endodontic cement based on calcium aluminate, has been evaluated. In addition, the properties of endodontic calcium aluminate cement (ECAC were compared with the gold standard mineral-trioxide-aggregate in contact with simulated body fluid (SBF. Manipulation tests and measurements of compressive strength, apparent porosity, setting time, pH and ionic conductivity were carried out on plain MTA and calcium aluminate cement with and without various additives

  8. In vitro activity of zinc oxide-eugenol and glass ionomer cements on Candida albicans Atividade in vitro dos cimentos de óxido de zinco e eugenol e ionômero de vidro sobre Candida albicans

    Directory of Open Access Journals (Sweden)

    Anna Carolina Aguiar Cassanho

    2005-06-01

    Full Text Available The aim of this study was to evaluate in vitro the antimicrobial activity of glass ionomer (GIC and zinc oxide-eugenol (ZOE cements against Candida albicans. Standardized GIC and ZOE specimens were maintained in contact with C. albicans suspension (1 ´ 10(6 cells/ml at 37°C for 24 h, 48 h or 7 days. A control group without any testing cement was included. After the incubation period, aliquots of 0.1 ml were plated on Sabouraud's agar, and then the number of colonies was counted. The results were expressed as values of logarithms of colony-forming units per milliliter (log CFU/mL and were analyzed statistically by Kruskal-Wallis ANOVA. After 48 h of incubation, the ZOE group presented no growth of C. albicans. GIC and control groups presented similar mean values at all tested periods. According to the results obtained, it could be concluded that, under the experimental conditions, ZOE cement was more effective in vitro against C. albicans than GIC.O objetivo deste estudo foi avaliar in vitro a atividade antimicrobiana dos cimentos de ionômero de vidro (CIV e óxido de zinco e eugenol (OZE sobre Candida albicans. Corpos-de-prova padronizados de CIV e OZE foram mantidos em contato com suspensão (1 ´ 10(6 células/ml de C. albicans a 37°C por 24 horas, 48 horas ou 7 dias. Um grupo controle sem nenhum cimento teste foi incluído. Após o período de incubação, alíquotas de 0,1 ml foram semeadas em ágar Sabouraud e o número de colônias foi contado. Os resultados foram expressos em logaritmos de valores de unidades formadoras de colônias por ml (log UFC/mL e analisados estatisticamente pelo teste ANOVA Kruskal-Wallis. Após 48 horas de incubação, o grupo OZE não apresentou crescimento de C. albicans. Os grupos CIV e controle apresentaram médias similares em todos os períodos testados. De acordo com os resultados obtidos, pode ser concluído que, sob as condições experimentais testadas, o cimento OZE apresentou-se mais efetivo in

  9. Resistência de união entre cimentos e liga de níquel-cromo, em função da ciclagem térmica e variações no procedimento de união Tensile bond strength between cements and nickel-chromium alloy related to thermocycling and adhesive variations

    Directory of Open Access Journals (Sweden)

    Ricardo Ruiz MARTUCI

    1999-07-01

    Full Text Available A investigação teve a finalidade de avaliar a resistência de união de uma liga de níquel-cromo com diversos agentes cimentantes frente à imersão, sem ou com termociclagem e idade. A liga usada foi a Litecast B. Os sistemas adesivos usados foram Ketac-Cem, Vitremer, Enforce com Flúor em três variações: a com primer apenas (Enforce P; b com primer e adesivo (Enforce P + A; c apenas adesivo (Enforce A. Discos metálicos, obtidos por fundição, foram cimentados entre si, constituindo os corpos de prova, que foram imersos em água destilada e submetidos ou não à ciclagem térmica. Os testes foram feitos 1 e 90 dias após a cimentação. As conclusões foram: o Ketac-Cem apresentou baixa resistência adesiva, sendo superado pelo Vitremer; o Enforce P, embora aumentasse a resistência ao longo do tempo, fez com que ela permanecesse baixa; o Enforce P + A apresentou alta resistência em um dia, que diminuiu ao longo do tempo; o Enforce A apresentou superioridade adesiva, que se manteve ao longo do tempo com ciclagem térmica; a influência da ciclagem térmica foi dependente do sistema adesivo.We evaluated tensile bond strengths between a nickel-chromium alloy and cements at different times (one and 90 days using or not thermocycling. Alloy used was Litecast B, and luting cements were Ketac-Cem, Vitremer, and Fluoride Enforce with three variations: a only primer; b with primer and bond; c only with bond. Metallic discs with 6 mm diameter were cemented together and immersed in distilled water. Half specimens were thermocycled and half one not. Conclusions were: Ketac-Cem presented low bonding strength, being that of Vitremer very higher; the material Enforce when used only with primer increased adhesion with time but yet remained relatively low after 90 days; Enforce used with bond only achieved superior adhesion, still present specially with termocycling after 90 days; influence of thermocycling depends on adhesive system.

  10. Portland, Oregon: Solar in Action (Brochure)

    Energy Technology Data Exchange (ETDEWEB)

    2011-10-01

    This brochure provides an overview of the challenges and successes of Portland, OR, a 2007 Solar America City awardee, on the path toward becoming a solar-powered community. Accomplishments, case studies, key lessons learned, and local resource information are given.

  11. How Valid Are the Portland Baseline Essays?

    Science.gov (United States)

    Martel, Erich

    1991-01-01

    Portland, Oregon's "African-American Baseline Essays," widely used in creating multicultural curricula, inaccurately depicts ancient Egyptians as black people and Olmec civilization as derived from African influences. The authors advance racial theories long abandoned by mainline Africa scholars, attribute mystical powers to pyramids,…

  12. Alkali binding in hydrated Portland cement paste

    NARCIS (Netherlands)

    Chen, W.; Brouwers, H.J.H.

    2010-01-01

    The alkali-binding capacity of C–S–H in hydrated Portland cement pastes is addressed in this study. The amount of bound alkalis in C–S–H is computed based on the alkali partition theories firstly proposed by Taylor (1987) and later further developed by Brouwers and Van Eijk (2003). Experimental data

  13. At the source of western science: the organization of experimentalism at the Accademia del Cimento (1657-1667).

    Science.gov (United States)

    Beretta, M

    2000-05-01

    The Accademia del Cimento, founded by the Medici princes, Ferdinando II, Grand Duke of Tuscany, and his brother, Leopoldo, later Cardinal, had members and programmes of research very different from earlier academies in Italy. The Cimento foreshadowed later European academies and institutions specifically devoted to research and improvement of natural knowledge. It issued only one publication, the Saggi di naturali esperienze, and most of the observations and experimental results from its brief life remain unpublished. The Roman Accademia fisica-matematica, associated with Queen Christina of Sweden, continued to some extent its emphasis on experiment, while The Royal Society, with which it maintained links, placed even greater reliance on experiment and its validation through unvarnished publication. Comparisons between the Cimento and its contemporaries, The Royal Society and the French academy, illuminate the origin of scientific institutions in the early modern period.

  14. Co-disposição de lodo centrifugado de Estação de Tratamento de Água (ETA em matriz de concreto: método alternativo de preservação ambiental Disposal of centrifuged sludge from Water Treatment Plant (WTP in concrete matrix: an alternative method for environmental protection

    Directory of Open Access Journals (Sweden)

    C. Hoppen

    2005-06-01

    Full Text Available O crescimento da demanda por água potável tem implicado em um aumento da quantidade de resíduos nas estações de tratamento de água (ETA. Apesar destes terem sido gerados por processo erosivo do solo nos mananciais que antecedem as ETAs, o tratamento químico requerido para a sua remoção obriga a uma disposição correta para não impactar, negativamente, o meio ambiente. Até agora, o destino mais comum para o lodo de ETA são os cursos d'água, mesmo ele sendo considerado um resíduo sólido. Neste trabalho, é proposta alternativa de co-disposição deste resíduo, ainda úmido, em matrizes de concreto, substituindo-se parcialmente seus insumos: os agregados miúdos e o cimento, cuja extração e emprego também causam impacto ambiental. Inicialmente, caracterizaram-se os insumos do concreto (cimento Portland CPII-F 32, areia e brita, além do lodo extraído da ETA Passaúna, localizada na região metropolitana de Curitiba. Para os estudos de dosagem, utilizou-se um concreto-referência (sem adição de lodo e traços de concreto com teores de 3, 5, 7 e 10% de lodo em relação ao peso de areia e em substituição à mesma. Nos concretos resultantes foram avaliadas propriedades tanto no estado fresco quanto no endurecido. O lodo é constituído, praticamente, de compostos de Si, Al e Fe, e do argilomineral do grupo caulinita, tendo teor de umidade em torno de 87%. Nos ensaios de resistência à compressão, as dosagens até 5% apresentaram um f c28 maior que 25 MPa. Para as dosagens com teores de lodo superiores a 5%, o f c28 foi menor, principalmente, para a dosagem de 10%. A análise dos dados permite concluir que os traços com até 5% de lodo podem ser aplicados em situações que vão desde a fabricação de artefatos e blocos até a construção de pavimentos em concreto de cimento Portland. Em relação às misturas com teores acima de 5%, a sua utilização é restrita a aplicações em que a trabalhabilidade não é um par

  15. Formação de biofilme bacteriano sobre polimetilmetacrilato usado como cimento ósseo

    OpenAIRE

    Flávio Ferraz de Campos Júnior

    2009-01-01

    A infecção bacteriana é a principal complicação que um procedimento de artroplastia de quadril ou joelho pode apresentar. Mesmo após a incorporação de antibiótico (gentamicina) ao cimento ósseo, as taxas de infecções após este procedimento cirúrgico continuam gerando sérios prejuízos para o hospital e para o paciente. As principais bactérias envolvidas nas infecções relacionadas aos implantes ortopédicos são Pseudomonas aeruginosa, Staphylococcus aureus e Staphylococcus epidermidis. O objetiv...

  16. Resistência de união imediata por tração de diferentes cimentos de ionômero de vidro a uma liga de Ni-Cr = Immediate tensile bond strength of different glass ionomer luting cements to a NiCr alloy

    Directory of Open Access Journals (Sweden)

    Ferraz, Roberta Penteado

    2005-01-01

    Full Text Available O objetivo deste estudo foi avaliar a resistência de união imediata por tração de diferentes cimentos de ionômero de vidro: convencional (Vidrion C, Vidrion C Caps, Ketac Cem, resinomodificado (Rely X, Protec Cem e o cimento de Fosfato de Zinco a uma liga de NiCr. Foram confeccionados pares de dispositivos metálicos em NiCr, com superfícies planas, próprios para a cimentação e testes de tração. Foram cimentados 12 pares metálicos de NiCr para cada agente cimentante, preparados de acordo com as recomendações do fabricante, totalizando 72 corpos de prova. Para manter os corpos de prova em posição e com carga constante durante a cimentação utilizou-se uma mesa metálica. Os corpos de prova foram armazenados em água destilada a 37° C durante 1 hora e, em seguida, submetidos aos testes de tração. Os resultados obtidos foram submetidos a ANOVA e Teste de Tukey (p < 0. 05. As médias de resistência, em MPa, encontradas foram: Vidrion C = 8,86; Vidrion C Caps = 10,91; Ketac Cem = 11,48; Rely X = 9,48; Protec Cem = 10,06; Fosfato de Zinco = 2,69. Todos os cimentos de ionômero de vidro testados apresentaram a média de resistência de união imediata por tração maior e estatisticamente significante que o cimento de Fosfato de Zinco. Não houve diferença significativa entre as médias de resistência obtidas para o Ketac-Cem, Vidrion C Caps, Protec Cem e Rely X, porém, o Ketac-Cem apresentou média estatisticamente significante e superior ao Vidrion C

  17. Avaliação, in vitro, da atividade antimicrobiana de três cimentos endodônticos = In vitro analysis of antimicrobial activity of three endodontic sealers

    Directory of Open Access Journals (Sweden)

    Kopper, Patrícia Maria Poli

    2007-01-01

    Full Text Available O presente estudo teve como objetivo avaliar, in vitro, a atividade antimicrobiana dos cimentos endodônticos AH Plus (A, Endofill (E e Sealer 26 (S, imediatamente após a manipulação, em contatos com culturas isoladas de E. faecalis (EF, P. aeruginosa (PA, S. aureus (SA e C. albicans (CA. Para tanto, foram confeccionados 9 corpos de prova de cada um dos materiais a partir de discos de papel filtro com 5 mm de diâmetro. Oito destes, 2 para cada microrganismo, foram colocados sobre placas de Petri, contendo meio de cultura Brain Hart Infusion-Agar (BHI-A inoculado. O último foi colocado sobre uma placa com meio de cultura estéril (controle de esterilidade. Uma placa com BHI-A não inoculado serviu de controle negativo. As placas foram levadas a estufa bacteriológica e 48 horas após realizou-se a medida dos halos de inibição de crescimento microbiano com auxilio de paquímetro digital. Para o grupo do A, E e S, respectivamente, a média dos halos, em milímetros, foi de: 0,70, 3,13 e 1,79 para EF; 1,08, 3,40 e 3,01 para PA; 0,72, 3,16 e 4,03 para SA; 1,32, 2,59 e 1,40 para CA. O controle negativo e o controle de esterilidade dos materiais evidenciaram ausência de crescimento microbiano. Conclui-se que todos os cimentos testados apresentaram atividade antimicrobiana em contato com as culturas estudadas, sendo que para EF, PA e CA a ordem crescente do diâmetro do halo de inibição foi: A, S e E. Para SA a ordem crescente foi: A, E e S

  18. INCORPORAÇÃO DE RESÍDUOS VEGETAIS E SEUS EFEITOS SOBRE AS CARACTERÍSTICAS FÍSICO-MECÂNICAS DE MISTURAS DE SOLO-CIMENTO PARA FINS DE CONSTRUÇÃO RURAL PLANT RESIDUES INCORPORATION EFFECTS ON PHYSICAL AND MECHANICAL CHARACTERISTICS OF SOIL-CEMENT MIXTURES FOR AGRICULTURAL BUILDINGS PURPOSES

    Directory of Open Access Journals (Sweden)

    Marcos Fernandes Oliveira

    2007-12-01

    Full Text Available

    O presente trabalho teve como objetivo avaliar o efeito da adição da casca de arroz e da casca da semente do capim braquiária, sobre as propriedades físico-mecânicas de misturas de solo-cimento e conseqüente análise de sua viabilidade técnica com vistas à fabricação de materiais de construção alternativos para fins rurais. Para tal, os resíduos foram triturados, peneirados e tratados em solução de cal e o solo submetido aos ensaios de caracterização segundo normas brasileiras. Os resíduos foram adicionados em substituição ao cimento, variando os teores de cimento e de resíduo vegetal desde 100% de cimento e 0% de resíduo, até 60% de cimento e 40% de resíduo. Posteriormente foram moldados corpos-de-prova cilíndricos que foram submetidos aos ensaios de compressão simples, aos sete, 28 e 56 dias, e de capacidade de absorção de água, aos sete dias da moldagem. Após análise dos resultados, pôde-se concluir que as misturas obtidas a partir da substituição parcial do cimento por 10% de resíduos mostram-se viáveis como matéria-prima na fabricação de elementos construtivos não estruturais, tais como, blocos e tijolos prensados, destinados às construções e instalações rurais.

    PALAVRAS-CHAVE: Solo-cimento, resíduos vegetais, construções rurais.

    The aim of this research was to evaluate the effect of rice and Brachiaria brizantha husks on physical and mechanical properties of soil-cement mixtures and, consequently, to analyse their technical feasibility to manufacture alternative building materials for agricultural purposes. Husks were ground, sieved, and treated in lime solution and soil submitted to characterisation tests according to Brazilian standards. The plant residues were added in substitution to the cement. The cement content and

  19. Cinza de palha de cana-de-açúcar como adição mineral em fibrocimento

    Directory of Open Access Journals (Sweden)

    Michelle S. Rodrigues

    2013-12-01

    Full Text Available O Brasil é o maior produtor mundial de cana-de-açúcar e sua indústria sucroalcooleira gera grande quantidade de resíduos líquidos e sólidos, dentre eles a palha da cana-de-açúcar. Com o objetivo de agregar valor a este resíduo produziu-se, neste trabalho, cinza de palha de cana-de-açúcar por meio da queima controlada a 700 °C e se avaliou sua aplicação como adição mineral em compósitos de fibrocimento. A cinza foi caracterizada pelas técnicas de fluorescência de raios X, difração de raios X, granulometria a laser e superfície específica. Nos compósitos foram avaliadas as propriedades de absorção de água, porosidade aparente, massa específica aparente, módulo de ruptura, energia específica, módulo de elasticidade e limite de proporcionalidade. A caracterização das cinzas indicou superfície específica e porosidade elevadas, além de apresentar um halo de amorficidade no seu difratograma. Compósitos produzidos com as cinzas mostraram características físicas e mecânicas similares àquelas do controle o que viabiliza a substituição parcial do cimento Portland por esse tipo de cinzas.

  20. Influência de aditivos sobre a trabalhabilidade de concretos refratários de ultra-baixo teor de cimento Influence of additives on the working time of ultra-low cement refractory castables

    Directory of Open Access Journals (Sweden)

    I. R. de Oliveira

    2003-03-01

    Full Text Available A trabalhabilidade de concretos refratários é determinada principalmente pela cinética de hidratação do ligante hidráulico. Têm-se observado que o processo de gelificação/hidratação desse material em meio aquoso é sensivelmente influenciado pela presença de aditivos dispersantes. Em virtude disso, este trabalho investigou a correlação entre a trabalhabilidade de concretos refratários de ultra-baixo teor de cimento no sistema Al2O3-SiC-SiO2-C e as características apresentadas por suspensões aquosas de cimento na presença de diferentes aditivos. A influência desses aditivos no processo de hidratação do cimento foi estudada através de ensaios de microscopia eletrônica de varredura, difração de raios X, sedimentação, condutividade elétrica e ensaios reológicos. Os resultados obtidos indicam que a "pega" inicial do concreto ocorre devido à aglomeração das partículas induzida pela formação de um produto coloidal amorfo ("gel" entre elas. Observou-se que o citrato de sódio favorece a formação de uma quantidade significativa de "gel" entre as partículas, reduzindo a trabalhabilidade do concreto.The working time of refractory castables is mainly determined by the hydration kinetic of the hydraulic binder. It has been observed that the gelation/hydration process of this material in aqueous solutions is significantly influenced by the addition of dispersing additives. Hence, this work investigated the correlation between the working time of ULC refractory castables in the Al2O3-SiC-SiO2-C system and the physic-chemical characteristics of cement aqueous suspensions in the presence of different sort of additives. The influence of these additives in the cement hydration process was studied by scanning electron microscopy, X-ray diffraction, sedimentation experiments, electrical conductivity and rheological tests. The initial setting of castables was found to be associated to particle coagulation and the development of

  1. Avaliação biomecânica do cimento ortopédico combinado com antibiótico e azul de metileno Biomechanical evaluation of orthopaedic cement combined with antibiotic and methylene blue

    Directory of Open Access Journals (Sweden)

    Marcos Felipe Marcatto de Abreu

    2009-01-01

    Full Text Available OBJETIVO: O cimento acrílico é utilizado há anos nas cirurgias ortopédicas, especialmente nas artroplastias do joelho, merecendo atenção também quando utilizado com o acréscimo de antibióticos (para tratamento de infecções ou corantes (para facilitação de uma possível retirada. Neste estudo procurou-se avaliar diferenças mecânicas entre o cimento ortopédico puro e quando misturado com antibiótico e/ou corante. MÉTODOS: Foram utilizados cimento acrílico ortopédico Surgical Simplex®P Stryker, vancomicina em pó e azul de metileno e as misturas submetidas a testes físicos e mecânicos de acordo com a norma ABNT NBR ISO 5833. Avaliou-se: tempo para a formação de massa, capacidade de intrusão, resistência à compressão, resistência ao dobramento (tensão e temperatura máxima atingida pelas misturas. RESULTADOS: As misturas avaliadas foram aprovadas quanto ao tempo de preparação da mistura, temperatura máxima alcançada, profundidade da intrusão e resistência à compressão. Somente aquela contendo apenas cimento puro foi aprovada no ensaio de flexão. CONCLUSÃO: O acréscimo de vancomicina e/ou azul de metileno ao cimento ortopédico Surgical Simplex®P Stryker reduz a resistência da mistura à flexão, sendo reprovada pela norma ABNT NBR ISO 5833.OBJECTIVE: Acrylic cement has been used for years on orthopaedic surgeries, especially on knee arthroplasties, deserving special attention when added to antibiotics (for treatment of deep bone infections or stains (to facilitate its removal. The present study was conducted in order to evaluate potential mechanical differences between the orthopaedic cement itself and when this is added to antibiotic and/or stains. METHODS: Surgical bone cement Simplex®P Stryker, vancomycin and methylene blue were used, and the mixtures were submitted to physical and mechanical tests according the ABNT NBR ISO 5833 rule. The parameters studied here were: time for mass formation

  2. Avaliação da integridade e da retenção de metais pesados em materiais estabilizados por solidificação Assessment of integrity and retention of heavy metals in materials stabilized by solidification

    Directory of Open Access Journals (Sweden)

    André Luiz Fiquene de Brito

    2009-03-01

    Full Text Available A quantidade de resíduos sólidos industriais tem aumentado significativamente em decorrência da industrialização, e o seu gerenciamento adequado é necessário para reduzir o impacto ao meio ambiente e aos ecossistemas. Neste trabalho, foram avaliadas a integridade e a retenção de metais pesados em materiais estabilizados por solidificação. Foi adotado o planejamento completamente aleatorizado com um único fator, ou seja, foram comparadas as médias de quatro tratamentos (A, B, C e D com 0, 40, 50 e 60% respectivamente de contaminantes e três repetições. Cimento Portland comum, bentonita sódica e hidróxido de cálcio foram usados para estabilizar por solidificação o resíduo sólido sintético contendo óxido de Cd2+, Pb2+ e Cu2+. Pode-se concluir que os tratamentos influenciaram no resultado de lixiviação do cádmio, chumbo e cobre. Os tratamentos mostraram que as concentrações do extrato solubilizado e lixiviado aumentam em função da quantidade de cádmio, chumbo e cobre adicionada. O maior valor encontrado foi para o material proveniente do tratamento D, que apresentou lixiviação igual a 32,815 mg.kg-1 para o cádmio e 29,769 mg.kg-1 para o chumbo. Para os ensaios de integridade/durabilidade, constatou-se que o aumento da absorção de água fez com que a resistência à compressão diminuísse. O uso de cimento, de hidróxido de cálcio e de bentonita sódica se mostrou ideal para retenção de metais pesados, evitando a sua lixiviação e a solubilização para o meio ambiente.As the quantity of hazardous industrial wastes increases significantly owing to rapid industrialization, its appropriate management is required to reduce adverse impacts on humans and ecosystems. This work evaluated the integrity and retention of heavy metals in materials stabilized by solidification. It was adopted a completely randomized design with a single factor, that is, the averages of four treatments were compared (A, B, C and D with 0

  3. Análise comparativa da resistência de união de um cimento convencional e um cimento autoadesivo após diferentes tratamentos na superfície de pinos de fibra de vidro

    OpenAIRE

    Juliana das Neves MARQUES; GONZALEZ,Carolina Brum; Eduardo Moreira da SILVA; Pereira,Gisele Damiana da Silveira; Simão,Renata Antoun; Maíra do PRADO

    2016-01-01

    Resumo Introdução Os pinos de fibra de vidro são uma alternativa aos núcleos metálicos e apresentam vantagens, tais como: estética, módulo de elasticidade semelhante à dentina e cimentação imediata após o término do tratamento endodôntico. Ainda, apresentam a capacidade de aderir ao cimento resinoso e este, à dentina, por meio de técnicas adesivas. Objetivo Comparar a adesão de um cimento resinoso convencional e um autoadesivo a pinos de fibra de vidro, e os efeitos de diferentes tratamento...

  4. Avaliação da dureza superficial de cimentos de ionômero de vidro reforçados por nanotubos de carbono

    Directory of Open Access Journals (Sweden)

    Mayra Manoella Perez Reis dos Santos

    Full Text Available Introdução Os cimentos de ionômero de vidro (CIV são materiais com baixa resistência à tração e ao cisalhamento, mostrando-se, portanto, contraindicados para áreas sujeitas às grandes cargas oclusais. Objetivo Avaliar o efeito da incorporação de nanotubos de carbono em CIV por meio de dureza superficial Knoop. Material e método Foram confeccionados 48 espécimes, divididos em quatro grupos, de acordo com o tipo de CIV (n=12 – convencional ou de alta viscosidade, incorporados ou não de nanotubos de carbono (NC a 2%: (A Vidrion R; (B Vidrion R + NC 2%; (C Vitro Molar, e (D Vitro Molar + NC 2%. Os espécimes foram preparados utilizando-se seringa Centrix, para inserção do material em moldes plásticos, e armazenados em água deionizada por 24 horas. Após polimento, realizou-se o teste de dureza superficial com penetrador do tipo Knoop. Foram realizadas cinco endentações em cada espécime, distanciadas entre si em 100 µm. Resultado Os valores médios de dureza foram 58,96 ± 8,29 (A, 34,81 ± 5,78 (B, 60,84 ± 4,91 (C e 41,97 ± 5,45 (D. O teste ANOVA detectou diferenças estatisticamente significantes para os dois parâmetros estudados, tipo de material (p=0,016 e inclusão de NC (p0,05, enquanto os grupos B e D apresentaram diferenças significativas (p<0,05. Ao comparar o fator incorporação ou não de NC, observou-se diferença significativa entre os grupos A e B, e entre os grupos C e D (p<0,05. Conclusão A incorporação de nanotubos de carbono influenciou negativamente os valores de dureza superficial para os dois tipos de CIV utilizados.

  5. "Avaliação da retenção de coroas metálicas fundidas em função dos tipos de agentes cimentantes e das ciclagens térmica e mecânica"

    OpenAIRE

    2005-01-01

    Nesta pesquisa, foram avaliados a retenção de coroas cimentadas sobre dentes terceiros molares humanos extraídos, após submetê-los às ciclagens térmica e mecânica, e o tipo de falha dos cimentos. Vinte dentes foram preparados de maneira padronizada, com 4 mm de altura, 8 mm de diâmetro e 20º de expulsividade. Coroas metálicas fundidas em NiCr foram cimentadas sobre os preparos, sendo dez com cimento de fosfato de zinco e dez com cimento resinoso, e armazenadas em água a 37ºC por 24 horas. Ale...

  6. 76 FR 2832 - National Emission Standards for Hazardous Air Pollutants From the Portland Cement Manufacturing...

    Science.gov (United States)

    2011-01-18

    ... the Portland Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants... (NESHAP) from the Portland Cement Manufacturing Industry and Standards of Performance (NSPS) for Portland Cement Plants. The final rules were published on September 9, 2010. This direct final action...

  7. 75 FR 54969 - National Emission Standards for Hazardous Air Pollutants From the Portland Cement Manufacturing...

    Science.gov (United States)

    2010-09-09

    ... Portland Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants; Final Rule... Hazardous Air Pollutants From the Portland Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants AGENCY: Environmental Protection Agency (EPA). ACTION: Final rule. SUMMARY: EPA...

  8. 77 FR 46371 - National Emission Standards for Hazardous Air Pollutants for the Portland Cement Manufacturing...

    Science.gov (United States)

    2012-08-03

    ... the Portland Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants... Standards for Hazardous Air Pollutants for the Portland Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants,'' which was published in the Federal Register on July 18, 2012....

  9. 76 FR 28318 - National Emission Standards for Hazardous Air Pollutants From the Portland Cement Manufacturing...

    Science.gov (United States)

    2011-05-17

    ... the Portland Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants... Pollutants emitted by the Portland Cement Industry and the New Source Performance Standards for Portland Cement Plants issued under sections 112(d) and 111(b) of the Clean Air Act, respectively. The EPA is...

  10. 76 FR 2860 - National Emission Standards for Hazardous Air Pollutants From the Portland Cement Manufacturing...

    Science.gov (United States)

    2011-01-18

    ... the Portland Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants... of Performance (NSPS) for Portland Cement Plants. The final rules were published on September 9, 2010... Portland Cement Manufacturing Industry Docket, Docket ID No. EPA-HQ-OAR-2002-0051, 1200 Pennsylvania...

  11. Radiopacity of portland cement associated with different radiopacifying agents.

    Science.gov (United States)

    Húngaro Duarte, Marco Antonio; de Oliveira El Kadre, Guâniara D'arc; Vivan, Rodrigo Ricci; Guerreiro Tanomaru, Juliane Maria; Tanomaru Filho, Mário; de Moraes, Ivaldo Gomes

    2009-05-01

    This study evaluated the radiopacity of Portland cement associated with the following radiopacifying agents: bismuth oxide, zinc oxide, lead oxide, bismuth subnitrate, bismuth carbonate, barium sulfate, iodoform, calcium tungstate, and zirconium oxide. A ratio of 20% radiopacifier and 80% white Portland cement by weight was used for analysis. Pure Portland cement and dentin served as controls. Cement/radiopacifier and dentin disc-shaped specimens were fabricated, and radiopacity testing was performed according to the ISO 6876/2001 standard for dental root sealing materials. Using Insight occlusal films, the specimens were radiographed near to a graduated aluminum stepwedge varying from 2 to 16 mm in thickness. The radiographs were digitized and radiopacity compared with the aluminum stepwedge using Digora software (Orion Corporation Soredex, Helsinki, Finland). The radiographic density data were converted into mmAl and analyzed statistically by analysis of variance and Tukey-Kramer test (alpha = 0.05). The radiopacity of pure Portland cement was significantly lower (p oxide and Portland cement/lead oxide presented the highest radiopacity values and differed significantly from the other materials (p oxide presented the lowest radiopacity values of all mixtures (p < 0.05). All tested substances presented higher radiopacity than that of dentin and may potentially be added to the Portland cement as radiopacifying agents. However, the possible interference of the radiopacifiers with the setting chemistry, biocompatibility, and physical properties of the Portland cement should be further investigated before any clinical recommendation can be done.

  12. Serviceability and Reinforcement of Low Content Whisker in Portland Cement

    Institute of Scientific and Technical Information of China (English)

    CAO Mingli; WEI Jianqiang; WANG Lijiu

    2011-01-01

    In order to explore the serviceability and reinforcement of CaCO3 whisker in portland cement matrix,the durability of CaCO3 whisker and effect of low whisker content(0%-4.0%)on the working performance and mechanical properties of portland cement were investigated.The experimental results show that CaCO3 whiskers have a good stability and serviceability in cement,and should not significantly alter the rheological properties of the cement paste.The flexural and compressive strength of portland cement reinforced by CaCO3 whiskers was increased by 33.3% and 12.83%,respectively.

  13. Durabilidade de compósito biomassa vegetal-cimento modificado por polímero Durability of cellulose-cement composites modified by polymer

    Directory of Open Access Journals (Sweden)

    Lia L. Pimentel

    2006-08-01

    Full Text Available A durabilidade de compósito biomassa vegetal-cimento é um dos fatores mais importantes para a colocação desse material no mercado consumidor. A utilização de polímeros em concreto e argamassa, com o objetivo de melhorar sua durabilidade, é cada vez mais freqüente. Este estudo visou à caracterização de propriedades físicas e mecânicas de compósito biomassa vegetal-cimento modificado com polímeros e a análise da durabilidade desse compósito. Foi testado um polímero de base acrílica em compósitos produzidos com resíduo de Pinus caribaea. Foram realizados ensaios de envelhecimento acelerado, por meio de ciclos de molhamento e secagem, por imersão em água quente e ensaio de envelhecimento natural. As propriedades físicas do compósito avaliadas foram a massa específica aparente e a absorção total de água por imersão. As propriedades mecânicas foram determinadas por meio de ensaios de resistência à tração na flexão, analisando-se a tensão e a energia de ruptura. Os corpos-de-prova foram extraídos de placas executadas por simples prensagem. Ensaios de microscopia eletrônica de varredura foram utilizados para observar o estado da fibra e da matriz após os processos de envelhecimento. O uso de polímero melhorou o desempenho mecânico do compósito nas primeiras idades e também promoveu significativa redução da capacidade de absorção de água, demonstrando que o uso desse material pode vir a melhorar a durabilidade desses compósitos, uma vez que reduziu sensivelmente sua capacidade de absorção.The durability of the cellulose-cement composites is a decisive factor to introduce such material in the market. Polymers have been used in concrete and mortar production to increase its durability. The goal of this work was the physical and mechanical characterization of cellulose-cement composites modified by a polymer and the subsequent durability evaluation. The work also evaluated the dispersion of acrylic

  14. Infiltração marginal de agentes cimentantes em coroas metálicas fundidas Marginal microleakage of cast metal crowns luting agents

    Directory of Open Access Journals (Sweden)

    Tomie Nakakuki de CAMPOS

    1999-12-01

    Full Text Available Um dos principais objetivos do cimento, que fixa a restauração protética ao dente, é o selamento da fenda existente entre os mesmos. Para avaliar a infiltração marginal, foram feitos preparos cavitários padronizados, em 20 dentes naturais extraídos. As coroas totais foram fundidas em NiCr, sendo 10 cimentadas com cimento de fosfato de zinco e 10 com cimento resinoso Panavia 21. As amostras foram submetidas à ciclagem térmica e em seguida foram colocadas em solução de azul de metileno a 0,5%. Após o seccionamento vestíbulo-lingual, os corpos-de-prova foram examinados com lupa de aumento. Houve diferença significante entre os dois cimentos testados, sendo que 100% das amostras cimentadas com cimento de fosfato de zinco apresentaram infiltração atingindo dentina e polpa e 100% das amostras cimentadas com Panavia 21 não sofreram qualquer tipo de infiltração. Conclui-se que: o cimento resinoso Panavia 21 apresentou melhores resultados, quanto ao grau de infiltração, quando comparado com o cimento de fosfato de zinco, na cimentação de coroas metálicas fundidas em NiCr.One of the main goals of the luting agent, which bonds the cast restoration to the prepared tooth, is to seal the gap between them. Standardized preparations were made on 20 extracted teeth in order to evaluate microleakage. The crowns were made in NiCr, and in one group of 10 crowns zinc phosphate was used as the luting agent; in the other 10, Panavia 21 was used. The samples were thermocycled and then put into methylene blue solution (0.5%. After buccolingual sectioning of the cemented crowns, the samples were examined with a magnifier. There was a significant difference between the two groups: 100% of the zinc phosphate cemented crowns presented microleakage reaching the dentin and the pulp and 100% of the samples with Panavia 21 did not suffer any microleakage. So, as to the marginal microleakage with cast metal crowns in NiCr, the Panavia 21 luting agent

  15. Influence of activation modes on diametral tensile strength of dual-curing resin cements Influência dos métodos de ativação na resistência à tração diametral de cimentos resinosos duais

    Directory of Open Access Journals (Sweden)

    Renata Garcia Fonseca

    2005-12-01

    Full Text Available In metallic restorations, the polymerization of dual-curing resin cements depends exclusively on chemical activation. The effect of the lack of photoactivation on the strength of these cements has been rarely studied. This study evaluated the influence of activation modes on the diametral tensile strength (DTS of dual-curing resin cements. Base and catalyst pastes of Panavia F, Variolink II, Scotchbond Resin Cement, Rely X and Enforce were mixed and inserted into cylindrical metal moulds (4 x 2 mm. Cements were either: 1 not exposed to light (chemical activation = self-cured groups or 2 photoactivated through mylar strips (chemical and photo-activation = dual-cured groups (n = 10. After a 24 h storage in 37ºC distilled water, specimens were subjected to compressive load in a testing machine. A self-curing resin cement (Cement-It and a zinc phosphate cement served as controls. Comparative analyses were performed: 1 between the activation modes for each dual-curing resin cement, using Student’s t test; 2 among the self-cured groups of the dual-curing resin cements and the control groups, using one-way ANOVA and Tukey’s test (alpha = 0.05. The dual-cured groups of Scotchbond Resin Cement (53.3 MPa, Variolink II (48.4 MPa and Rely X (51.6 MPa showed higher DTS than that of self-cured groups (44.6, 40.4 and 44.5 MPa respectively (p 0.05. The self-cured groups of all the dual-curing resin cements presented statistically the same DTS as that of Cement-It (44.1 MPa (p > 0.05, and higher DTS than that of zinc phosphate (4.2 MPa. Scotchbond Resin Cement, Variolink II and Rely X depended on photoactivation to achieve maximum DTS. In the absence of light, all the dual-curing resin cements presented higher DTS than that of zinc phosphate and statistically the same as that of Cement-It (p > 0.05.Em restaurações metálicas, a polimerização dos cimentos resinosos duais depende exclusivamente da ativação química. Há poucas pesquisas sobre o efeito

  16. EnviroAtlas - Portland, OR - Atlas Area Boundary

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset shows the boundary of the Portland, OR Atlas Area. It represents the outside edge of all the block groups included in the EnviroAtlas Area....

  17. Portland, Maine Tsunami Forecast Grids for MOST Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Portland, Maine Forecast Model Grids provides bathymetric data strictly for tsunami inundation modeling with the Method of Splitting Tsunami (MOST) model. MOST...

  18. EFFECT OF PORTLAND-POZZOLAN CEMENTS ON CONCRETE MATURITY

    Directory of Open Access Journals (Sweden)

    Arın YILMAZ

    2004-03-01

    Full Text Available The maturity concept expressed by the combined effect of time and temperature on the concrete is a useful technique for prediction of the strength gain of concrete. According to maturity concept, samples of the same concrete at same maturity whatever combination of temperature and time, have approximately the same strength. Many maturity functions have been proposed for the last 50 years. The validity of these functions are only for ordinary portland cements. In this study, the suitable of traditional maturity functions for different types of Portland-pozzolan cements were investigated and a new maturity-strength relationship was tried to be established. For this purpose, four different pozzolans and one Portland cement was selected. Portland-pozzolan cements were prepared by using three different replacement amounts of % 5, % 20 and 40 % by weight of cement.

  19. Modification of Portland cement mortars with cactus gum

    OpenAIRE

    Hernandez-Zaragoza, Juan-Bosco; Caballero-Badillo, Carlos-Eduardo; Rosas-Juarez, Arnulfo; Lopez-Lara, Teresa; Hinojosa-Torres, Jaime; Castano, Victor-Manuel

    2007-01-01

    ????????, ?? ?????????? ??????? ?? ?????? ????????-???????, ??? ???????????????? ? ????????? ???????????, ???????????? ?????????? ?????????? ??????, ????????? ? ????????? ?????????????? ???????. ???????? ?????????? ???????? ??? ????????? ???????? ??? ????????? ?? 65 %, ????????? ?? ???????????? ?????????. Portland cement-based mortars of the standard type used for modern constructions, were modified by adding liophilized cactus gum, extracted froman indigenous Mexican cactus. The results show...

  20. EnviroAtlas - Portland, OR - Ecosystem Services by Block Group

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset presents environmental benefits of the urban forest in 1176 block groups in Portland, Oregon. Carbon attributes, temperature reduction,...

  1. EnviroAtlas - Portland, ME - Ecosystem Services by Block Group

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset presents environmental benefits of the urban forest in 146 block groups in Portland, Maine. Carbon attributes, temperature reduction,...

  2. Langstroth hive construction with cement-vermiculite Construção de colméia Langstroth com cimento-vermiculita

    Directory of Open Access Journals (Sweden)

    Maria Cristina Affonso Lorenzon

    2004-12-01

    Full Text Available Exfoliated vermiculite is a light-weight and cheap product that, because of its thermal resistance, has become a valuable insulating material. With regard to its use in beekeeping, this research tested whether the box for honey bees constructed with cement-vermiculite mortar (CVM presents physical characteristics similar to those of wood. The experiment was carried out at Seropédica, RJ, Brazil, for eight months. The cement-vermiculite mortar was compared with a control material (pinewood, in the construction of Langstroth boxes and boards, in a completely randomized design, with respect to thermal control, thermal conductivity and its capacity to absorb and lose water. The production cost for a CVM box was estimated. There were no internal temperature differences between CVM and wooden boxes. Thermal conductivity values for CVM and pinewood were similar. CVM absorbed more water and lost water faster than pinewood. Since CVM boxes can be easily constructed, at a low cost and with similar characteristics as traditional boxes, made of wood, the material can be recommended for use in non-migratory beekeeping.A vermiculita expandida é um material leve, barato e sua resistência térmica permite sua utilização como material isolante. Referente ao seu uso na Apicultura, esta pesquisa testou se a caixa para abelhas melíferas construída com argamassa cimento-vermiculita (ACV apresenta características similares às da madeira. O estudo foi realizado em Seropédica (ERJ, Brasil, durante oito meses. Comparou-se a argamassa com o material controle, que foi a madeira pinho, em caixas de abelhas e em placas, em um delineamento inteiramente casualizado, quanto ao: controle térmico, a condutividade térmica, a capacidade de absorver e perder água. O custo de produção da caixa ACV para abelhas foi estimado. Não se observaram diferenças da temperatura interna entre as caixas de ACV e de madeira. A condutividade térmica foi similar nas placas de ACV

  3. Rice husk derived waste materials as partial cement replacement in lightweight concrete Utilização de resíduos derivados da casca de arroz como substitutos parciais do cimento no concreto leve

    Directory of Open Access Journals (Sweden)

    Celso Yoji Kawabata

    2012-10-01

    Full Text Available In this study rice husk ash (RHA and broiler bed ash from rice husk (BBA, two agricultural waste materials, have been assessed for use as partial cement replacement materials for application in lightweight concrete. Physical and chemical characteristics of RHA and BBA were first analyzed. Three similar types of lightweight concrete were produced, a control type in which the binder was just CEMI cement (CTL and two other types with 10% cement replacement with, respectively, RHA and BBA. All types of similar lightweight concrete were prepared to present the same workability by adjusting the amount of superplasticizer. Properties of concrete investigated were compressive and flexural strength at different ages, absorption by capillarity, resistivity and resistance to chloride ion penetration (CTH method and accelerated carbonation. Test results obtained for 10% cement replacement level in lightweight concrete indicate that although the addition of BBA conducted to lower performance in terms of the degradation indicative tests, RHA led to the enhancement of mechanical properties, especially early strength and also fast ageing related results, further contributing to sustainable construction with energy saver lightweight concrete.Neste trabalho, cinzas de casca de arroz (RHA e cinzas de cama de frango (BBA, dois resíduos agrícolas, foram avaliadas para uso como substitutos parciais do cimento para produção de concreto leve. Características físicas e químicas de RHA e BBA foram analisadas. Três tipos semelhantes de concreto leve foram produzidos, um controle em que o ligante era totalmente cimento CEM I (CTL e dois outros tipos de concreto, com substituição de 10% com RHA e BBA, respectivamente. Todos os tipos de concreto leve foram feitos através do ajuste da quantidade de superplastificante para apresentarem a mesma trabalhabilidade. Propriedades de concreto investigados foram resistência à compressão e à flexão em diferentes idades

  4. Avaliação clínica de um cimento de ionômero de vidro utilizado como selante oclusal: a clinical evaluation Use of a glass ionomer cement as an occlusal sealant

    Directory of Open Access Journals (Sweden)

    Pedro Cheque BERNARDO

    2000-03-01

    Full Text Available Sabendo-se do papel do flúor na Odontologia Preventiva, cada vez mais procuram-se materiais restauradores com propriedades de liberação deste íon. Dentre os selantes oclusais, grande expectativa existe em relação aos cimentos de ionômero de vidro, particularmente os fotopolimerizáveis, por possuírem melhores propriedades. O objetivo deste trabalho foi testar um destes cimentos, Vitremer (3M, aplicado em: combinação ou não com um adesivo. A avaliação foi realizada em 159 dentes, 6 e 12 meses após a aplicação do selante, observando-se sua retenção e a presença ou ausência de lesão de cárie. Concluiu-se que a técnica modificada, com adesivo, propiciou significativamente melhor retenção após 6 e 12 meses que a técnica convencional, não havendo diferença entre molares e pré-molares. Apenas um dente do grupo sem adesivo desenvolveu lesão de cárie após a perda do material.Since fluoride’s properties are widely known in the field of Preventive Dentistry, fluoride-releasing materials have been extensively investigated. Among the occlusal sealants, there is great expectation regarding the results that can be achieved with light-curing glass-ionomer cements due to their excellent properties. The aim of this study was to assess the use of one of these cements, Vitremer (3M as an occlusal sealant. The material was applied using two different techniques; either associated or not with an adhesive system. After 6 and 12 months of observation, an evaluation was performed in 159 teeth to verify its retention as well as the presence of caries lesions. The technique that included the adhesive system showed better retention than the conventional one. Total retention was 84.9% for the experimental technique and 37.2% for the conventional technique after 12 months. There was no difference between bicuspids and molars regarding retention. Caries lesion was observed in a single tooth, for which a total loss of material was observed

  5. Iterated transportation simulations for Dallas and Portland

    Energy Technology Data Exchange (ETDEWEB)

    Nagel, K.; Simon, P.; Rickert, M.; Esser, J.

    1998-09-02

    The goal of the TRansportation ANalysis and SIMulation System (TRANSIMS) is to combine the most important aspects of human decision-making related to transportation, from activities planning (sleep, work, eat, shop,...) via modal and route planning to driving, into a single, consistent methodological and software framework. This is meant to combine the functionalities of activities-based travel demand generation, modal choice and route assignment, and micro-simulation. TRANSIMS attempts to employ advanced methodologies in all these modules. Yet, it is probably the overall framework that is the most important part of this attempt. It is, for example, possible to replace the TRANSIMS microsimulation by another micro-simulation that uses the same input and generates the same output. TRANSIMS uses specific regions as examples in order to ensure that the technology is rooted in the real world. Until about the middle of 1997, an approximately five miles by five miles area in Dallas/Texas was used. Since then, TRANSIMS has moved to using data from Portland/Oregon; a case study for this region is planned to be completed by the end of the year 2000. In this paper the authors give short descriptions of these projects and give references to related publications.

  6. Alkali segregation in Portland cement pastes

    Directory of Open Access Journals (Sweden)

    Triviño, F.

    1966-09-01

    Full Text Available Not availableEn el presente trabajo se pone de manifiesto experimentalmente la formación y presencia de aphthitalita -sulfato doble de potasio y sodio en la relación S04K2/S04Na2 = 3/1 en las pastas puras de cemento portland, desde el comienzo del fraguado de las mismas. Se estudia el mecanismo de la citada formación, íntimamente relacionada con el proceso general de formación de eflorescencias salinas, a base de una emigración de sulfatos alcalinos hacia las partes externas de las pastas, en virtud de fenómenos de exudación equivalentes a arrastres capilares. Se sintetiza y aísla la aphthitalita por dos procedimientos y se obtiene su difractograma.de rayos· X, a efectos de su identificación y de la confirmación de los resultados experimentales obtenidos, así como de la interpretación de los mismos.

  7. Alternative Fuel for Portland Cement Processing

    Energy Technology Data Exchange (ETDEWEB)

    Schindler, Anton K; Duke, Steve R; Burch, Thomas E; Davis, Edward W; Zee, Ralph H; Bransby, David I; Hopkins, Carla; Thompson, Rutherford L; Duan, Jingran; ; Venkatasubramanian, Vignesh; Stephen, Giles

    2012-06-30

    The production of cement involves a combination of numerous raw materials, strictly monitored system processes, and temperatures on the order of 1500 °C. Immense quantities of fuel are required for the production of cement. Traditionally, energy from fossil fuels was solely relied upon for the production of cement. The overarching project objective is to evaluate the use of alternative fuels to lessen the dependence on non-renewable resources to produce portland cement. The key objective of using alternative fuels is to continue to produce high-quality cement while decreasing the use of non-renewable fuels and minimizing the impact on the environment. Burn characteristics and thermodynamic parameters were evaluated with a laboratory burn simulator under conditions that mimic those in the preheater where the fuels are brought into a cement plant. A drop-tube furnace and visualization method were developed that show potential for evaluating time- and space-resolved temperature distributions for fuel solid particles and liquid droplets undergoing combustion in various combustion atmospheres. Downdraft gasification has been explored as a means to extract chemical energy from poultry litter while limiting the throughput of potentially deleterious components with regards to use in firing a cement kiln. Results have shown that the clinkering is temperature independent, at least within the controllable temperature range. Limestone also had only a slight effect on the fusion when used to coat the pellets. However, limestone addition did display some promise in regards to chlorine capture, as ash analyses showed chlorine concentrations of more than four times greater in the limestone infused ash as compared to raw poultry litter. A reliable and convenient sampling procedure was developed to estimate the combustion quality of broiler litter that is the best compromise between convenience and reliability by means of statistical analysis. Multi-day trial burns were conducted

  8. Shear bond strength of glass-ionomer cements to dentin: Effects of dentin depth and type of material activation Resistência ao cisalhamento da união de cimentos de ionômero de vidro à dentina: Efeitos da profundidade do substrato e do tipo de ativação do material

    Directory of Open Access Journals (Sweden)

    Elda PISANESCHI

    1997-01-01

    Full Text Available The purpose of this study was to determine, through the shear bond strength of in vitro tests, that the type of glass-ionomer cements (conventional or hybrid and dentin depth (superficial or deep are factors that may influence the adhesion of these materials to the dentin structure. Specimens of two conventional glass-ionomer cements (Vidrion R® - SS White and Chelon Fil®- Espe and a hybrid-glass ionomer cement (Vitremer® - 3M were separated in groups and prepared for the shear bond strength test. The results submitted to statistical analysis were (all values are in MPa: Group I - Vidrion R - superficial dentin 1.97 (± 0.56; deep dentin 3.15 (± 1.51; Group II - Chelon Fil - superficial dentin 2.43 (± 1.43; deep dentin 3.21 (± 0.89; and Group III - Vitremer - superficial dentin 7.04 (± 2.04; deep dentin 10.30 (± 1.99. There were significant differences between dentin depth and type of materialsA proposta deste trabalho foi determinar, através da resistência ao cisalhamento em testes in vitro, se o tipo de cimento de ionômero de vidro, convencional ou híbrido, e a profundidade de dentina, superficial ou profunda, são fatores que influenciam a adesão desses materiais na estrutura dentinária. Espécimes de dois cimentos convencionais (Vidrion R® - SSWhite e Chelon Fil®- Espe e um cimento de ionômero de vidro híbrido (Vitremer®- 3M foram divididos em grupos. Os resultados (todos os valores em MPa submetidos à análise estatística foram: Grupo I - Vidrion R - dentina superficial, 1,97 (± 0,56; dentina profunda, 3,15 (± 1,51; Grupo II - Chelon Fil - dentina superficial, 2,43 (± 1,43; dentina profunda, 3,21 (± 0,89; e Grupo III - Vitremer - dentina superficial, 7,04 (± 2,04; dentina profunda, 10,30(± 1,99. Houve diferenças significantes entre a profundidade de dentina e o tipo de ativação do material

  9. Avaliação in vitro da atividade antibacteriana de um cimento odontológico à base de óleo-resina de Copaifera multijuga Hayne In vitro assessment of antibacterial activity of a dental cement constituted of a Copaifera multijuga Hayne oil-resin

    Directory of Open Access Journals (Sweden)

    Kátia Regina Felizardo Vasconcelos

    2008-12-01

    Full Text Available Um dos materiais utilizados para a adequação do meio bucal no serviço público é o cimento produzido a partir de óxido de zinco e eugenol. Entretanto, o eugenol é uma substância citotóxica que pode desencadear alguns efeitos adversos. Por essa razão, procura-se substituir o eugenol por uma substância que apresente baixa toxicidade, mantendo ou mesmo melhorando as propriedades do cimento. O óleo-resina de copaíba é um produto natural, utilizado pelas populações amazônicas e reconhecido por suas propriedades medicinais. Baseando-se nas propriedades desse óleo-resina, na ação antimicrobiana comprovada do hidróxido de cálcio e na ação anti-séptica do óxido de zinco, propôs-se formular um cimento odontológico obtido da associação do ZnO, Ca(OH2 e óleo-resina de Copaifera multijuga Hayne e avaliar sua atividade antibacteriana através do teste de diluição em meio líquido frente às cepas padrão de Streptococcus mutans (ATCC 25175 e S. sanguinis (ATCC 15300. Nesse ensaio, utilizaram-se os seguintes grupos experimentais: o cimento contendo ZnO, Ca(OH2 e óleo-resina de copaíba (G1 e cada um dos constituintes isoladamente, ZnO (G2, Ca(OH2 (G3 e óleo-resina de copaíba (G4. Todos os grupos analisados demonstraram atividade antibacteriana, o G4 apresentou os melhores resultados e o G1 mostrou-se um cimento promissor a ser utilizado em odontologia.One of the materials utilized for suitability of the oral means in the public service is the cement produced from zinc oxide and eugenol. However, eugenol is a cytotoxic substance that can trigger some adverse effects. For this reason, it is desired to replace eugenol for another substance that presents low toxicity, keeping or even improving the cement properties. The copaiba oil-resin is a natural product, utilized by the Amazonian population and recognized for its medicinal properties. Based on the properties of this oil-resin, on the proven antimicrobial activity of calcium

  10. EnviroAtlas - Portland, OR - One Meter Resolution Urban Land Cover Data (2012)

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Portland, OR land cover dataset includes data for the Portland metropolitan area plus the city of Vancouver, Washington and various smaller towns and rural areas...

  11. EnviroAtlas - Portland, OR - One Meter Resolution Urban Land Cover (2012) Web Service

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Portland, OR land cover web service includes data for the Portland metropolitan area plus the city of Vancouver, Washington and various smaller towns and rural...

  12. Apatite formation on calcined kaolin-white Portland cement geopolymer.

    Science.gov (United States)

    Pangdaeng, S; Sata, V; Aguiar, J B; Pacheco-Torgal, F; Chindaprasirt, P

    2015-06-01

    In this study, calcined kaolin-white Portland cement geopolymer was investigated for use as biomaterial. Sodium hydroxide and sodium silicate were used as activators. In vitro test was performed with simulated body fluid (SBF) for bioactivity characterization. The formation of hydroxyapatite bio-layer on the 28-day soaked samples surface was tested using SEM, EDS and XRD analyses. The results showed that the morphology of hydroxyapatite was affected by the source material composition, alkali concentration and curing temperature. The calcined kaolin-white Portland cement geopolymer with relatively high compressive strength could be fabricated for use as biomaterial. The mix with 50% white Portland cement and 50% calcined kaolin had 28-day compressive strength of 59.0MPa and the hydroxyapatite bio-layer on the 28-day soaked sample surface was clearly evident.

  13. Pavement management and rehabilitation of portland cement concrete pavements

    Science.gov (United States)

    Zegeer, C. V.; Agent, K. R.; Rizenbergs, R. L.; Curtayne, P. C.; Scullion, T.; Pedigo, R. D.; Hudson, W. R.; Roberts, F. L.; Karan, M. A.; Haas, R.

    Pavement management and rehabilitation projects and techniques are discussed. The following topics are discussed: economic analyses and dynamic programming in resurfacing project selection; implementation of an urban pavement management system; pavement performance modeling for pavement management; illustration of pavement management: from data inventory to priority analysis; rehabilitation of concrete pavements by using portland cement concrete overlays; pavement management study: Illinois tollway pavement overlays; resurfacing of plain jointed-concrete pavements; design procedure for premium composite pavement; model study of anchored pavement; prestressed concrete overlay at O'Hare International Airport: in-service evaluation; and, bonded portland cement concrete resurfacing.

  14. 40 CFR 81.51 - Portland Interstate Air Quality Control Region.

    Science.gov (United States)

    2010-07-01

    ... Quality Control Regions § 81.51 Portland Interstate Air Quality Control Region. The Portland Interstate Air Quality Control Region (Oregon-Washington) has been revised to consist of the territorial area... Portland Interstate Air Quality Control Region (Oregon-Washington) will be referred to by...

  15. 78 FR 10005 - National Emission Standards for Hazardous Air Pollutants for the Portland Cement Manufacturing...

    Science.gov (United States)

    2013-02-12

    ... Standards for Hazardous Air Pollutants for the Portland Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants; Final Rule #0;#0;Federal Register / Vol. 78 , No. 29 / Tuesday... RIN 2060-AQ93 National Emission Standards for Hazardous Air Pollutants for the Portland...

  16. 77 FR 42367 - National Emission Standards for Hazardous Air Pollutants for the Portland Cement Manufacturing...

    Science.gov (United States)

    2012-07-18

    ... Standards for Hazardous Air Pollutants for the Portland Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants; Proposed Rule #0;#0;Federal Register / Vol. 77 , No. 138 / Wednesday...-AQ93 National Emission Standards for Hazardous Air Pollutants for the Portland Cement...

  17. 76 FR 76760 - Gray Portland Cement and Cement Clinker From Japan

    Science.gov (United States)

    2011-12-08

    ... Portland Cement and Cement Clinker From Japan Determination On the basis of the record \\1\\ developed in the... antidumping duty order on gray Portland cement and cement clinker from Japan would be likely to lead to... the Commission are contained in USITC Publication 4281 (December 2011), entitled Gray Portland...

  18. 76 FR 78240 - Gray Portland Cement and Clinker From Japan: Continuation of Antidumping Duty Order

    Science.gov (United States)

    2011-12-16

    ... International Trade Administration Gray Portland Cement and Clinker From Japan: Continuation of Antidumping Duty... antidumping duty order on gray portland cement and clinker from Japan, pursuant to section 751(c) of the... International Trade Commission (ITC) that revocation of the antidumping duty order on gray portland cement...

  19. Laboratory Investigation on the Strength Gaining of Brick Aggregate Concrete Using Ordinary Portland Cement and Portland Composite Cement

    Directory of Open Access Journals (Sweden)

    Hoque M H, Numen E H, Islam N., Mohammed

    2014-05-01

    Full Text Available This study focused on the laboratory investigation of strength variation of brick aggregate concrete made with ordinary Portland cement (OPC and Portland composite cement (PCC.The investigation was conducted by testing concrete cylinder specimens at different ages of concrete with concrete mix ratios: 1:1.5:3 and 1:2:4 by volume and with water cement ratios=0.45 and 0.60. The test result reveals that at the early age, concrete composed with OPC attained larger compressive strength than the concrete made of PCC. However, in the later age concrete made with PCC achieved higher strength than OPC.

  20. Análise da influência de dois processos distintos de moagem nas propriedades do pó precursor e do cimento de beta-TCP Analysis of the influence of two different milling processes on the properties of beta-TCP precursor powder and cement

    Directory of Open Access Journals (Sweden)

    H. A. I. Cardoso

    2012-06-01

    Full Text Available São várias as características que tem colocado os cimentos de fosfato de cálcio em evidência na área dos biomateriais, como sua bioatividade e reabsorção in vivo. Neste trabalho, analisou-se a influência de dois processos de moagem nas propriedades morfológicas do pó de [beta]-fosfato tricálcico, [beta]-TCP, e na resistência mecânica do cimento. O pó foi obtido via reação no estado sólido de CaCO3 e CaHPO4 a 1050 ºC, apresentando pureza de fase e ausência de elementos tóxicos. O pó foi moído em: (A moinho de bolas e (B moinho vibratório de alta energia; sendo analisado por MEV e distribuição granulométrica. Os pós apresentaram propriedades diferentes com relação à distribuição e tamanho médio de grão. Finalmente, o cimento preparado com o pó submetido ao processo (B apresentou valores de resistência mecânica significativamente maiores que o preparado com o pó submetido ao processo (A. Conclui-se que o processo de moagem (B é muito mais eficiente que o processo (A.There are several characteristics that put calcium phosphate cements in evidence, like its bioactivity and in vivo resorption. The influence of two milling processes on the morphological properties of the [beta]-tricalcium phosphate powder, [beta]-TCP, and in the mechanical properties of the cement were analyzed. The powder was obtained by solid state reaction of CaCO3 and CaHPO4 at 1050 ºC. It showed high phase purity and absence of toxic elements. The powder was processed in ball mill (A and high-energy vibratory mill (B, with posterior analysis by SEM and particle size distribution. The powders showed different average and distribution of grain size. Finally, the cement prepared with powder submitted to process (B showed values of axial tensile strength significantly greater than that prepared with powder submitted to process (A. The milling process (B is much more efficient than the process (A.

  1. Portland cement-blast furnace slag blends in oilwell cementing applications

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, D.T.; DiLullo, G.; Hibbeler, J. [and others

    1995-12-31

    Recent investigations of blast furnace slag cementing technologies. have been expanded to include Portland cement/blast furnace slag blends. Mixtures of Portland cement and blast furnace slag, while having a long history of use in the construction industry, have not been used extensively in oilwell cementing applications. Test results indicate that blending blast furnace slag with Portland cement produces a high quality well cementing material. Presented are the design guidelines and laboratory test data relative to mixtures of blast furnace slag and Portland cements. Case histories delineating the use of blast furnace slag - Portland cement blends infield applications are also included.

  2. 76 FR 81475 - Foreign-Trade Zone 45-Portland, OR

    Science.gov (United States)

    2011-12-28

    ... privileged foreign (PF) status (19 CFR 146.41) inputs in manufacturing of ink for inkjet printer cartridges... would be either inkjet ink (duty rate--1.8%) or inkjet printer cartridges (duty- free). New material... Portland Inc. ] (Inkjet Ink Manufacturing), Hillsboro, OR An application has been submitted to the...

  3. Dehydration kinetics of Portland cement paste at high temperature

    NARCIS (Netherlands)

    Zhang, Q.; Ye, G.

    2012-01-01

    Portland cement paste is a multiphase compound mainly consisting of calcium-silicate-hydrate (CSH) gel, calcium hydroxide (CH) crystal, and unhydrated cement core. When cement paste is exposed to high temperature, the dehydration of cement paste leads to not only the decline in strength, but also th

  4. Hydration process in Portland cement blended with activated coal gangue

    Institute of Scientific and Technical Information of China (English)

    Xian-ping LIU; Pei-ming WANG; Min-ju DING

    2011-01-01

    This paper deals with the hydration of a blend of Portland cement and activated coal gangue in order to determine the relationship between the degree of hydration and compressive strength development.The hydration process was investigated by various means:isothermal calorimetry,thermal analysis,non-cvaporable water measurement,and X-ray diffraction analysis.The results show that the activated coal gangue is a pozzolanic material that contributes to the hydration of the cement blend.The pozzolanic reaction occurs over a period of between 7 and 90 d,consuming portlandite and forming both crystal hydrates and ill-crystallized calcium silicate hydrates.These hydrates are similar to those found in pure Portland cement.The results show that if activated coal gangue is substituted for cement at up to 30% (w/w),it does not significantly affect the final compressive strength of the blend.A long-term compressive strength improvement can in fact be achieved by using activated coal gangue as a supplementary cementing material.The relationship between compressive strength and degree of hydration for both pure Portland cement and blended cement can be described with the same equation.However,the parameters are different since blended cement produces fewer calcium silicate hydrates than pure Portland cement at the same degree of hydration.

  5. Avaliação da influência do tratamento térmico do silano sobre a resistência de união entre cimentos resinosos e uma cerâmica feldspática

    OpenAIRE

    Carvalho, Ronaldo Luís Almeida de

    2013-01-01

    O objetivo do presente estudo foi avaliar três hipóteses: H0- O tratamento térmico do silano e o tipo de cimento resinoso não influencia na resistência de união entre cimentos resinosos e uma cerâmica feldspática; H1- O tratamento térmico do silano influencia na resistência de união entre cimentos resinosos e uma cerâmica feldspática; H2- O cimento resinoso influencia na resistência de união de uma cerâmica feldspática. Foram confeccionados 30 blocos cerâmicos (VITA Mark II, Zahnfabrik), os q...

  6. 77 FR 17409 - Foreign-Trade Zone 45-Portland, OR Expansion of Manufacturing Authority Epson Portland, Inc...

    Science.gov (United States)

    2012-03-26

    ... of certain PF status inputs in the manufacturing of ink for inkjet printer cartridges within Subzone... Portland, Inc. (Inkjet Ink); Notice of Approval of Restricted Authority On December 22, 2011, the Port of... involved the use of privileged foreign (PF) status (19 CFR 146.41) inputs in manufacturing of ink...

  7. Projeto da reologia de concretos refratários zero-cimento no sistema Al2O3-SiC-C

    Directory of Open Access Journals (Sweden)

    Oliveira I. R. de

    2001-01-01

    Full Text Available Concretos refratários no sistema Al2O3-SiC-C vêm sendo utilizados principalmente no revestimento de canais de corrida de altos-fornos. A associação dessas matérias-primas tem elevado o desempenho dos concretos refratários frente às severas condições de trabalho, devido ao aumento da resistência ao choque térmico e ao ataque por escória e metal fundido. Apesar disso, o nível de conhecimento científico sobre a dispersão das partículas desse sistema multifásico é limitado. Neste trabalho, suspensões representativas da matriz de concretos refratários zero-cimento no sistema Al2O3-SiC-C foram preparadas para a avaliação da eficiência de aditivos na dispersão simultânea de diferentes matérias-primas, bem como para a análise do comportamento reológico da matriz em função do pH e teor de aditivo. Os ácidos poliacrílico e cítrico e um surfactante não iônico foram usados como dispersantes. Os valores de viscosidade aparente e tensão de escoamento obtidos foram usados para construir mapas de estabilidade da matriz. Medidas de pH e fluidez de concretos preparados com diferentes teores de aditivo mostraram que as condições iniciais de pH não foram correspondentes à região ótima de dispersão estabelecida pelos mapas de estabilidade. O uso de altos teores de ácido cítrico, bem como, o deslocamento do pH do concreto na direção da região ótima de dispersão foram eficientes para otimizar a sua fluidez.

  8. City of Portland: Businesses for an environmentally sustainable tomorrow

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-12-01

    The sustainable business development program in Portland (OR) is known as BEST. BEST stands for Businesses for an Environmentally Sustainable Tomorrow. The Portland Energy Office operates BEST as a {open_quotes}one-stop service center{close_quotes} for business owners and managers. BEST provides information and assistance on resource efficient buildings and business practices. The results of BEST`s two years of operation have been generally impressive. Nearly 150 new or expanding businesses have been connected with utility design assistance programs. Businesses have also received assistance with water conservation, telecommuting, construction debris recycling, and alternative fuel vehicles. BEST has received local and national publicity and BEST services have been the topic at more than a dozen conferences, meetings, or other speaking engagements. A guidebook for communities wishing to start a similar program will be available in early 1996.

  9. Microdureza superficial do cimento resinoso de ativado por duas diferentes fontes de luz com interposição de cerômero e porcelana

    OpenAIRE

    Alencar Júnior, Emmanuel Arraes de [UNESP

    2005-01-01

    Nessa pesquisa utilizou-se de três unidades fotoativardoras na polimerização de uma marca comercial de cimento resinoso de dupla ativação, com a interposição de uma lâmina de cerômero e de porcelana, para avaliar a microdureza superficial do cimento resinoso, considerando sua superfície do topo e da base Os corpos-de-prova foram confeccionados utilizando-se matrizes metálicas com 2mm de espessura e 16mm de diâmetro, com o orifício central medindo 8mm de diâmetro (figura 4), coincidindo com o ...

  10. Estudo da influência da radiação ionizante na tração diametral de cimentos de ionômero de vidro

    OpenAIRE

    Carvalho, Lígia Maria Nogarett Pibernat de

    2013-01-01

    Este estudo teve como objetivo avaliar a influência da radiação ionizante sobre três cimentos de ionômero de vidro, convencional, modificado por resina e modificado por liga de prata, quanto à tração diametral. A hipótese nula deste estudo testou a ação da radiação ionizante sobre os cimentos de ionômero de vidro submetidos a tração diametral. Para o teste de tração diametral foram confeccionadas amostras para cada grupo de ionômero de vidro: Convencional (n=20), modificado por resina (n=20),...

  11. Effect of one-bottle adhesive systems on the fluoride release of a resin-modified glass ionomer Efeito dos sistemas adesivos de frasco único na liberação de flúor de um cimento de ionômero de vidro modificado por resina

    Directory of Open Access Journals (Sweden)

    Linda Wang

    2004-03-01

    Full Text Available A dhesive systems associated to resin-modified glass ionomer cements are employed for the achievement of a higher bond strength to dentin. Despite this benefit, other properties should not be damaged. This study aimed at evaluating the short-time fluoride release of a resin-modified glass ionomer cement coated with two one-bottle adhesive systems in a pH cycling system. Four combinations were investigated: G1: Vitremer (V; G2: Vitremer + Primer (VP; G3: Vitremer + Single Bond (VSB and G4: Vitremer + Prime & Bond 2.1 (VPB. SB is a fluoride-free and PB is a fluoride-containing system. After preparation of the Vitremer specimens, two coats of the selected adhesive system were carefully applied and light-cured. Specimens were immersed in demineralizing solution for 6 hours followed by immersion in remineralizing solution for 18 hours, totalizing the 15-day cycle. All groups released fluoride in a similar pattern, with a greater release in the beginning and decreasing with time. VP showed the greatest fluoride release, followed by V, with no statistical difference. VSB and VPB released less fluoride compared to V and VP, with statistical difference. Regardless the one-bottle adhesive system, application of coating decreased the fluoride release from the resin-modified glass ionomer cements. This suggests that this combination would reduce the beneficial effect of the restorative material to the walls around the restoration.Sistemas adesivos são associados aos cimentos de ionômero de vidro modificados por resina para a obtenção de maior resistência adesiva à dentina. Apesar deste benefício, outras propriedades não devem ser prejudicadas. Este estudo se propôs a avaliar a liberação de flúor a curto prazo de um cimento de ionômero de vidro modificado por resina coberto com dois diferentes sistemas adesivos em um modelo de ciclagem de pH. Quatro associações foram testadas: G1: Vitremer (V; G2: Vitremer + Primer (VP; G3: Vitremer + Single

  12. Corrosion inhibitor mechanisms on reinforcing steel in Portland cement pastes

    Science.gov (United States)

    Martin, Farrel James

    2001-07-01

    The mechanisms of corrosion inhibitor interaction with reinforcing steel are investigated in the present work, with particular emphasis on effects associated with corrosion inhibitors admixed into Portland cement paste. The principal objective in reinforcing steel corrosion inhibition for Portland cement concrete is observed to be preservation of the naturally passive steel surface condition established by the alkaline environment. Introduction of chloride ions to the steel surface accelerates damage to the passive film. Excessive damage to the passive film leads to loss of passivity and a destabilization of conditions that facilitate repair of the passive film. Passive film preservation in presence of chloride ions is achieved either through stabilization of the passive film or by modification of the chemical environment near the steel surface. Availability of inhibitors to the steel surface and their tendency to stabilize passive film defects are observed to be of critical importance. Availability of admixed corrosion inhibitors to the passive film is affected by binding of inhibitors during cement paste hydration. It is determined that pore solution concentrations of inorganic admixed inhibitors tend to be lower than the admixed concentration, while pore solution concentrations of organic admixed inhibitors tend to be higher than the admixed concentration. A fundamental difference of inhibitor function is observed between film-forming and defect stabilizing corrosion inhibitors. Experiments are conducted using coupons of reinforcing steel that are exposed to environments simulating chloride-contaminated Portland cement concrete. A study of the steel/cement paste interface is also performed, and compounds forming at this interface are identified using X-Ray diffraction.

  13. 40 CFR 81.78 - Metropolitan Portland Intrastate Air Quality Control Region.

    Science.gov (United States)

    2010-07-01

    ... Quality Control Region. 81.78 Section 81.78 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Air Quality Control Regions § 81.78 Metropolitan Portland Intrastate Air Quality Control Region. The Metropolitan Portland Intrastate Air Quality Control Region (Maine) consists of the territorial...

  14. 33 CFR 100.1302 - Special Local Regulation, Annual Dragon Boat Races, Portland, Oregon.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Special Local Regulation, Annual Dragon Boat Races, Portland, Oregon. 100.1302 Section 100.1302 Navigation and Navigable Waters COAST... § 100.1302 Special Local Regulation, Annual Dragon Boat Races, Portland, Oregon. (a) Regulated area....

  15. Índices de conforto térmico e respostas fisiológicas de bezerros da raça holandesa em bezerreiros individuais com diferentes coberturas Thermal comfort indexes and physiological responses of holstein calves in individual houses with different roofings

    Directory of Open Access Journals (Sweden)

    Celso Y. Kawabata

    2005-12-01

    Full Text Available Este trabalho avaliou a eficiência de abrigos para bezerros, a partir de índices de conforto térmico (carga térmica radiante, índice de temperatura de globo e umidade e índice de globo negro, pela comparação entre abrigos cobertos por telha de cimento-amianto e telha de cimento- celulose. O experimento foi implantado num sistema de abrigos convencionais, tipo boxe, com cinco tratamentos: telhados de cimento-amianto, cimento-celulose, cimento-celulose pintado de branco e telhado duplo de cimento-celulose, todos expostos ao sol, e telhado de cimento-celulose em área sombreada. Foram realizadas cinco repetições (um bezerro por repetição, de setembro a novembro de 2002, em Pirassununga - SP. As variáveis fisiológicas registradas foram freqüência respiratória e temperatura retal. Os abrigos expostos ao sol e com telha de cimento-amianto apresentaram os índices menos satisfatórios quanto ao conforto térmico animal, em relação aos demais abrigos ao sol. Os abrigos com telhas de cimento-celulose e em área sombreada apresentaram os melhores índices de conforto térmico animal. Os resultados das variáveis fisiológicas foram melhores para o tratamento posicionado à sombra. Encontrou-se relação entre os resultados de conforto térmico e os fisiológicos, em especial para a freqüência respiratória.This work was focused in the efficiency of housing for calves, based on thermal comfort indexes (radiant thermal load, black globe humidity index and black globe index. It was compared animal housing covered with commercial corrugated sheets produced with asbestos cement and cellulose cement tiles. The experiment was carried out in a system of conventional housing, box type, with five treatments: roofs with asbestos cement tiles, cellulose cement tiles, cellulose cement painted tiles and double layer of cement cellulose tiles, all of them exposed to the sunlight and cement cellulose roof under shade. The experiment involved five

  16. 76 FR 24519 - Gray Portland Cement and Cement Clinker From Japan; Institution of a Five-Year Review Concerning...

    Science.gov (United States)

    2011-05-02

    ... COMMISSION Gray Portland Cement and Cement Clinker From Japan; Institution of a Five-Year Review Concerning the Antidumping Duty Order on Gray Portland Cement and Cement Clinker From Japan AGENCY: United States... determine whether revocation of the antidumping duty order on gray portland cement and cement clinker...

  17. 76 FR 54206 - Gray Portland Cement and Clinker From Japan: Final Results of the Expedited Third Sunset Review...

    Science.gov (United States)

    2011-08-31

    ... International Trade Administration Gray Portland Cement and Clinker From Japan: Final Results of the Expedited... review of the antidumping duty order on gray portland cement and clinker from Japan. As a result of this... duty order on gray portland cement and clinker from Japan \\1\\ pursuant to section 751(c) of the...

  18. Una nota sobre los Hormigones de Cemento Portland (HCP y Hormigones de Cemento Portland con Adiciones (HCPA

    Directory of Open Access Journals (Sweden)

    Talero Morales, Rafael

    1993-09-01

    Full Text Available El hombre contemporáneo ha dividido el proceso evolutivo de la humanidad en macroperíodos de tiempo relacionados con avances significativos obtenidos en el campo de los materiales. Así se define la edad de piedra, bronce, hierro, cobre, etc. Y siguiendo esta tendencia, probablemente las generaciones futuras podrán hablar de esta época como la "edad del hormigón" y mostrar los monumentales vestigios que, en su mayor parte, se han construido con hormigón de cemento portland.

  19. Influence of the sealer and a plug in coronal leakage after post space preparation Influência do cimento obturador e de um "plug" na infiltração coronária após preparo para pino

    Directory of Open Access Journals (Sweden)

    Roberto Holland

    2004-09-01

    Full Text Available The subject of this paper was to conduct an in vitro study of the coronal leakage after root canal filling and post space preparation. One hundred single-rooted human teeth had their crowns removed and the canals prepared and filled by the lateral condensation technique with gutta-percha points and the sealers CRCS and Endofill (a Grossman cement. After post space preparation, the remainder of the filling was protected or not with 1mm of a plug of the following materials: Coltosol, Super Bonder (cyanoacrylate-ester, CRCS and Endofill. After 24 hours in saline, the specimens were immersed in a 2% methylene blue solution in a vacuum environment for 24 hours. The teeth were then sectioned longitudinally, leakage was evaluated linearly and the obtained data were submitted to the Kruskal-Wallis test. The results with the two sealers studied were similar between themselves and worse (pO objetivo deste trabalho foi avaliar "in vitro" a infiltração marginal coronária após obturação de canal e preparo para pino, empregando-se ou não um "plug" protetor. Cem dentes humanos unirradiculares extraídos tiveram suas coroas removidas, e os canais preparados biomecanicamente e obturados pela técnica da condensação lateral com cones de guta-percha e os cimentos CRCS e Endofill. Após preparo para pino, os remanescentes das obturações foram ou não protegidos por 1 mm de um "plug" dos seguintes materiais: Coltosol, Super Bonder, CRCS e Endofill. Após permanecerem 24 horas em soro fisiológico, os espécimes foram imersos em solução de azul de metileno a 2%, em ambiente com vácuo, por 24 horas. Os dentes foram então seccionados longitudinalmente, as infiltrações marginais mensuradas linearmente, e os dados obtidos submetidos à análise de variância e teste de Kruskal-Wallis. Os resultados com os 2 cimentos estudados foram semelhantes entre si e piores (ñ<0,01 do que os grupos com "plugs" protetores. A análise estatística ordenou os grupos

  20. Compósitos de cimento - borracha de pneus: efeito da escória nas propriedades Tire rubber-cement composites: effect of slag on properties

    Directory of Open Access Journals (Sweden)

    N. Segre

    2006-12-01

    Full Text Available Compósitos de cimento-borracha de pneus preparados com cimentos tipo I e contendo adições de três diferentes escórias foram estudados. Resistência à flexão, absorção de água e resistência ao ataque ácido foram investigadas. Um decréscimo no módulo de ruptura (MOR foi observado para todos os corpos de prova contendo borracha, quando comparados com os corpos de prova sem borracha (controles. Para as pastas controle e com borracha e argamassas controle, preparadas com cimento com escória, o MOR aumenta com o aumento da atividade hidráulica da escória utilizada, até valores indistinguíveis dos obtidos para as argamassas e pastas preparadas com cimento tipo I. Argamassas com borracha apresentaram valores de MOR independentes do cimento utilizado. Uma redução na sorção de água é observada para corpos de prova controle e contendo borracha, preparados com todos os cimentos contendo adição de escória, quando comparados com os corpos de prova preparados com cimento tipo I. Para corpos de prova de argamassa com borracha, quanto mais baixa é a basicidade da escória, menor é a sorção de água dos compósitos. Estes resultados indicam baixa porosidade e consequentemente uma melhor adesão entre a borracha e a matriz de cimento nestes corpos de prova. Além disso, uma velocidade menor de sorção de água é observada para os corpos de prova com borracha, com destaque para os corpos de prova com cimento que contém a escória menos básica, quando comparados com os controles. Resultados de ataque ácido aos corpos e prova de argamassas, preparadas com os cimentos contendo adição de escória, mostram que a susceptibilidade dos corpos de prova frente à degradação por ácido é governada não somente por aspectos microestruturais, como porosidade e permeabilidade, mas também por aspectos químicos, como diferenças na quantidade de álcalis presentes nas escórias ou quantidade de escória não reagida nos corpos de prova

  1. Effect of three natural pozzolans in portland cement hydration

    Directory of Open Access Journals (Sweden)

    Rahhal, V.

    2003-03-01

    Full Text Available Natural pozzolans have been used since ancient times and continues to be used today. The chemistry and morphological composition of natural pozzolans and their particle size distribution allows classifying them as more or less reactive pozzolan. In this research several techniques have been used to study the influence of pozzolan on portland cement hydration as much as to evaluate the mechanical and durable properties of concretes, mortars and pastes containing pozzolans. This paper describes the effect of incorporating three natural pozzolans to two cements with very different mineralogical composition. The techniques used were: conduction calorimetry and Fratini test. Results proved that pozzolanic activity and the acceleration and retardation of hydration reaction depend on the mineralogical composition of the portland cernent used. Effects of dilution, stimulation, acceleration or retardation reactions, behavior into areas of heat dissipation and pozzolanic activity depend on the percentage of pozzolan used and the age in which it has been analyzed.

    El uso de las puzolanas naturales se remonta a la antigüedad, no obstante, actualmente continúa su utilización. La composición química y morfológica de las puzolanas naturales, sumado al tamaño de sus partículas, las califican como más o menos reactivas. En el estudio de las mismas, se han aplicado variadas técnicas para el análisis de sus interferencias en las reacciones de hidratación de los cementos portland; así como para la evaluación de las propiedades resistentes y duraderas que pueden conferirle a los hormigones, morteros o pastas de los que formen parte. Este trabajo versará sobre los efectos que produce la incorporación de tres puzolanas naturales a dos cementos portland de muy diferente composición mineralógica. Las técnicas aplicadas para su estudio han sido: la calorimetría de conducción y el ensayo de Fratini. Los resultados obtenidos permiten determinar

  2. Avaliação da dureza superficial de cimentos resinosos após cimentação de pinos de fibra de vidro: efeito de profundidade de polimerização e sistemas adesivos

    OpenAIRE

    Jardim, Patrícia dos Santos [UNESP

    2004-01-01

    Os pinos pré-fabricados de fibra de vidro têm sido o sistema de escolha para reconstrução de dentes anteriores tratados endodonticamente e o sucesso da cimentação dos pinos de fibra de vidro está associado à cimentação do tipo adesiva, sendo que o agente cimente normalmente utilizado é um cimento resinoso de dupla polimerização, entretanto questiona-se a eficácia dos cimentos de dupla polimerização, principalmente nas regiões muito distantes da fonte de luz, bem como sua compatibilidade quími...

  3. Avaliação quantitativa da microinfiltração em cavidades de classe V restauradas com materiais hibridos de ionomero de vidro/resina composta

    OpenAIRE

    Claudia Salami de Magalhães

    1997-01-01

    Resumo: O objetivo deste estudo "in vitro" foi avaliar quantitativamente a microinfiltração em cavidades de classe V restauradas com materiais híbridos de ionômero de vidro/resina composta, comparando-os com um cimento de ionômero de vidro e com um sistema de resina composta/adesivo dentinário. Foram preparadas cavidades cilíndricas na superfície radicular de 105 dentes humanos extraídos, a cerca de 4 mm da junção amelo-cemeotária. Os dentes foram divididos aleatoriamente em cinco grupos, cad...

  4. Simple Queueing Model Applied to the City of Portland

    Science.gov (United States)

    Simon, Patrice M.; Esser, Jörg; Nagel, Kai

    We use a simple traffic micro-simulation model based on queueing dynamics as introduced by Gawron [IJMPC, 9(3):393, 1998] in order to simulate traffic in Portland/Oregon. Links have a flow capacity, that is, they do not release more vehicles per second than is possible according to their capacity. This leads to queue built-up if demand exceeds capacity. Links also have a storage capacity, which means that once a link is full, vehicles that want to enter the link need to wait. This leads to queue spill-back through the network. The model is compatible with route-plan-based approaches such as TRANSIMS, where each vehicle attempts to follow its pre-computed path. Yet, both the data requirements and the computational requirements are considerably lower than for the full TRANSIMS microsimulation. Indeed, the model uses standard emme/2 network data, and runs about eight times faster than real time with more than 100 000 vehicles simultaneously in the simulation on a single Pentium-type CPU. We derive the model's fundamental diagrams and explain it. The simulation is used to simulate traffic on the emme/2 network of the Portland (Oregon) metropolitan region (20 000 links). Demand is generated by a simplified home-to-work destination assignment which generates about half a million trips for the morning peak. Route assignment is done by iterative feedback between micro-simulation and router. An iterative solution of the route assignment for the above problem can be achieved within about half a day of computing time on a desktop workstation. We compare results with field data and with results of traditional assignment runs by the Portland Metropolitan Planning Organization. Thus, with a model such as this one, it is possible to use a dynamic, activities-based approach to transportation simulation (such as in TRANSIMS) with affordable data and hardware. This should enable systematic research about the coupling of demand generation, route assignment, and micro

  5. Liberação de fluor e aluminio e efeito anticariogenico de cimentos de ionomero de vidro : estudo "in situ"

    OpenAIRE

    Roberta Dalcico

    2002-01-01

    Resumo: Vários trabalhos in vitro e in vivo mostram que os cimentos de ionômero de vidro (CIVs) são capazes de diminuir cáries recorrentes. Além disso, alguns estudos têm sugerido que esses materiais podem apresentar efeito inibitório sobre a microbiota cariogênica. Tal efeito tem sido atribuído a alguns componentes liberados pelo material, entre eles flúor (F) e alumínio (AI). Desta maneira, o objetivo deste estudo foi analisar bioquímica e microbiologicamente a placa formada sobre dois cime...

  6. Avaliação das propriedades mecânicas de quatro cimentos de ionômero de vidro convencionais utilizados na cimentação de bandas ortodônticas Evaluation of mechanical properties of four conventional glass ionomer cements used in orthodontic bands cementation

    Directory of Open Access Journals (Sweden)

    Diego Andrei Aguiar

    2008-06-01

    Full Text Available OBJETIVO: objetivo deste estudo foi comparar a resistência flexural, resistência à compressão e resistência à tração diametral de quatro diferentes cimentos de ionômero de vidro convencionais utilizados para cimentação de bandas ortodônticas (Vidrion C/SS White; Meron/Voco; Ketac Cem/3M ESPE; Vivaglasss/Ivoclar-Vivadent. METODOLOGIA: foram confeccionados 12 corpos-de-prova para cada cimento, em cada teste, seguindo a norma 66 da ADA para resistência à tração diametral e à compressão, e norma 4049 da ISO para resistência flexural. Os testes foram feitos após 24 horas de armazenagem em água destilada a 37ºC, na máquina de testes Universal Instron 4444 sob velocidade de 0,75mm/minuto para resistência flexural e 1mm/min para resistência à tração diametral e à compressão. Os resultados obtidos para o teste de resistência flexural foram: 25,85 ± 5,43MPa (Meron; 21,85 ± 6,96MPa (Vidrion C; 20,85 ± 4,17MPa (Vivaglass; 20,50 ± 4,89MPa (Ketac Cem. Para o teste de compressão os resultados foram (na mesma ordem: 77,72 ± 20,21MPa; 56,49 ± 8,54MPa; 47,84 ± 9,25MPa; 81,93 ± 13,37MPa. RESULTADOS: os resultados para o teste de resistência à tração diametral foram (na mesma ordem: 9,59 ± 2,09MPa; 5,25 ± 1,29MPa; 7,69 ± 2,09MPa; 4,08 ± 1,32MPa. RESULTADOS: os quatro cimentos mostraram-se estatisticamente equivalentes quanto ao teste de resistência flexural. Os cimentos Meron e Ketac Cem foram estatisticamente mais resistentes à compressão que o Vidrion C e o Vivaglass. Em relação ao teste de resistência à tração diametral, o cimento Meron mostrou-se estatisticamente superior aos demais.AIM: The aim of this in vitro study was to compare the flexural strength, the compressive strength and the diametral tensile strength of four conventional glass-ionomer cements (Vidrion C/SS White; Meron/Voco; Ketac Cem/3M ESPE; Vivaglass/Ivoclar-Vivadent used in Orthodontics for band cementation. METHODS: Twelve specimens of

  7. Research on the nanolevel influence of surfactants on structure formation of the hydrated Portland cement compositions

    Directory of Open Access Journals (Sweden)

    Guryanov Alexander

    2016-01-01

    Full Text Available The research of the structure formation process on a nanolevel of the samples of hydrated Portland cement compositions containing the modifying additives has been conducted with the help of small angle neutron scattering method. Carbonate and aluminum alkaline slimes as well as the complex additives containing surfactants were used as additives. The influence of slimes and surfactants on structural parameters change of Portland cement compositions of the average size of the disseminating objects, fractal dimension samples is considered. These Portland cement compositions are shown to be fractal clusters.

  8. Contribution to Portland cement hemihydrite and gypsum content determination

    Directory of Open Access Journals (Sweden)

    Moreno Arús, F.

    1974-09-01

    Full Text Available Not availableLa mayoría de los técnicos de cemento eceptan que las anormalidades del fraguado, conocidas como "falso fraguado" en el cemento portland, se deben primordialmente a la presencia de yeso parcialmente deshidratado (SO4Ca 1/2H2O. Si el clinker que se muele está enriquecido en cal libre, o la temperatura del molino es elevada (superior a los 110 ºC o hay escasa ventilación de éste, se llega a originar una parcial deshidratación del yeso, que se mantiene durante el proceso de ensilado y origina las anormalidades del fraguado anteriormente referidas. Por esta razón creemos muy importante el poder conocer el grado de deshidratación en que se encuentra el yeso en un cemento.

  9. Pulpotomies with portland cement in human primary molars

    Directory of Open Access Journals (Sweden)

    Taísa Regina Conti

    2009-02-01

    Full Text Available Two clinical cases in which Portland cement (PC was applied as a medicament after pulpotomy of mandibular primary molars in children are presented. Pulpotomy using PC was carried out in two mandibular first molars and one mandibular second molar, which were further followed-up. At the 3, 6 and 12-month follow-up appointments, clinical and radiographic examinations of the pulpotomized teeth and their periradicular area revealed that the treatments were successful in maintaining the teeth asymptomatic and preserving pulpal vitality. Additionally, the formation of a dentin bridge immediately below the PC could be observed in the three molars treated. PC may be considered as an effective alternative for primary molar pulpotomies, at least in a short-term period. Randomized clinical trials with human teeth are required in order to determine the suitability of PC before unlimited clinical use can be recommended.

  10. The Portland Basin: A (big) river runs through it

    Science.gov (United States)

    Evarts, Russell C.; O'Connor, Jim E.; Wells, Ray E.; Madin, Ian P.

    2009-01-01

    Metropolitan Portland, Oregon, USA, lies within a small Neogene to Holocene basin in the forearc of the Cascadia subduction system. Although the basin owes its existence and structural development to its convergent-margin tectonic setting, the stratigraphic architecture of basin-fill deposits chiefly reflects its physiographic position along the lower reaches of the continental-scale Columbia River system. As a result of this globally unique setting, the basin preserves a complex record of aggradation and incision in response to distant as well as local tectonic, volcanic, and climatic events. Voluminous flood basalts, continental and locally derived sediment and volcanic debris, and catastrophic flood deposits all accumulated in an area influenced by contemporaneous tectonic deformation and variations in regional and local base level.

  11. Influence of Cellulose Ethers on Hydration Products of Portland Cement

    Institute of Scientific and Technical Information of China (English)

    MA Baoguo; OU Zhihua; JIAN Shouwei; XU Rulin

    2011-01-01

    Cellulose ethers are widely used to mortar formulations, and it is significant to understand the interaction between cellulose ethers and cement pastes. FT-IR spectra, thermal analysis and SEM are used to investigate hydration products in the cement pastes modified by HEMC and HPMC in this article. The results show that the hydration products in modified cement pastes were finally identical with those in the unmodified cement paste, but the major hydration products, such as CH (calcium hydroxide), ettringite and C-S-H, appeared later in the modified cement pastes than in the unmodified cement paste. The cellulose ethers decrease the outer products and increase inner products of C-S-H gels. Compared to unmodified cement pastes, no new products are found in the modified cement pastes in the present experiment. The HEMC and HPMC investigation shows almost the same influence on the hydration products of Portland cement.

  12. Hydration of Portland cement with additions of calcium sulfoaluminates

    Energy Technology Data Exchange (ETDEWEB)

    Le Saout, Gwenn, E-mail: gwenn.le-saout@mines-ales.fr [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Lothenbach, Barbara [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Hori, Akihiro [DENKA Chemicals GmbH, Wehrhahn-Center, Cantadorstr. 3, D-40211 Duesseldorf (Germany); Higuchi, Takayuki [Denki Kagaku Kogyo Kabushiki Kaisha (DENKA), Omi, Itoigawa, Niigata, 949-0393 (Japan); Winnefeld, Frank [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland)

    2013-01-15

    The effect of mineral additions based on calcium aluminates on the hydration mechanism of ordinary Portland cement (OPC) was investigated using isothermal calorimetry, thermal analysis, X-ray diffraction, scanning electron microscopy, solid state nuclear magnetic resonance and pore solution analysis. Results show that the addition of a calcium sulfoaluminate cement (CSA) to the OPC does not affect the hydration mechanism of alite but controls the aluminate dissolution. In the second blend investigated, a rapid setting cement, the amorphous calcium aluminate reacts very fast to ettringite. The release of aluminum ions strongly retards the hydration of alite but the C-S-H has a similar composition as in OPC with no additional Al to Si substitution. As in CSA-OPC, the aluminate hydration is controlled by the availability of sulfates. The coupling of thermodynamic modeling with the kinetic equations predicts the amount of hydrates and pore solution compositions as a function of time and validates the model in these systems.

  13. Simple queueing model applied to the city of Portland

    Energy Technology Data Exchange (ETDEWEB)

    Simon, P.M.; Nagel, K. [Los Alamos National Lab., NM (United States)]|[Santa Fe Inst., NM (United States)

    1998-07-31

    The authors present a simple traffic micro-simulation model that models the effects of capacity cut-off, i.e. the effect of queue built-up when demand is exceeding capacity, and queue spillback, i.e. the effect that queues can spill back across intersections when a congested link is filled up. They derive the model`s fundamental diagrams and explain it. The simulation is used to simulate traffic on the emme/2 network of the Portland (Oregon) metropolitan region (20,000 links). Demand is generated by a simplified home-to-work assignment which generates about half a million trips for the AM peak. Route assignment is done by iterative feedback between micro-simulation and router. Relaxation of the route assignment for the above problem can be achieved within about half a day of computing time on a desktop workstation.

  14. Detecting flaws in Portland cement concrete using TEM horn antennae

    Science.gov (United States)

    Al-Qadi, Imad L.; Riad, Sedki M.; Su, Wansheng; Haddad, Rami H.

    1996-11-01

    To understand the dielectric properties of PCC and better correlate them with type and severity of PCC internal defects, a study was conducted to evaluate PCC complex permittivity and magnetic permeability over a wideband of frequencies using both time domain and frequency domain techniques. Three measuring devices were designed and fabricated: a parallel plate capacitor, a coaxial transmission line, and transverse electromagnetic (TEM) horn antennae. The TEM horn antenna covers the microwave frequencies. The measurement technique involves a time domain setup that was verified by a frequency domain measurement. Portland cement concrete slabs, 60 by 75 by 14 cm, were cast; defects include delamination, delamination filled with water, segregation, and chloride contamination. In this paper, measurements using the TEM horn antennae and the feasibility of detecting flaws at microwave frequency are presented.

  15. Dispersão e comportamento reológico de concretos refratários ultra-baixo teor de cimento no sistema Al2O3-SiC-SiO2-C Dispersion and setting control of ultra-low cement refractory castables in the Al2O3-SiC-SiO2-C system

    Directory of Open Access Journals (Sweden)

    I. R. de Oliveira

    2003-03-01

    Full Text Available Concretos refratários no sistema Al2O3-SiC-SiO2-C vêm sendo amplamente utilizados em indústrias siderúrgicas como revestimento de canais de corrida de altos-fornos, em virtude principalmente da sua elevada refratariedade aliada a altas resistências ao choque térmico e ao ataque por escória e metal fundido. Neste trabalho, investigou-se a influência de diferentes tipos de aditivos na trabalhabilidade e dispersão de concretos refratários de ultra-baixo teor de cimento nesse sistema. Apesar da sua alta capacidade de complexar íons de cálcio, moléculas de citrato não foram capazes de controlar adequadamente o tempo de pega do concreto estudado, contradizendo a idéia geral de que os íons de citrato devem ser utilizados para controlar a sua trabalhabilidade. Por outro lado, o aditivo polimetacrilato de sódio mostrou-se eficiente na otimização simultânea da dispersão e da trabalhabilidade do concreto devido provavelmente ao retardamento da dissolução dos íons advindos do cimento.Refractory castables in the Al2O3-SiC-SiO2-C system have been extensively used as linings for blast furnace runners, due mainly to their improved resistance to thermal shock damage and to slag and metal corrosion, respectively. In this work, ULC refractory castables in the Al2O3-SiC-SiO2-C system were prepared in order to evaluate the efficiency of different sort of additives on their dispersion and setting behavior. Although citrate ions are known to be efficient chelating agents, they were not able to properly control the working time of the castable studied, contradicting the general idea that citrate ions are necessary for controlling castable setting. On the other hand, the sodium polymethacrylate additive was found to be more efficient for the simultaneous optimization of the castable dispersion state and working time. This may be attributed to a retardation effect imparted by polymethacrylate molecules on the dissolution of ions from the surface

  16. Sulfate resistance of ordinary Portland cement with fly ash

    Directory of Open Access Journals (Sweden)

    Irassar, Edgardo F.

    1989-03-01

    Full Text Available Low calcium fly ash has demonstrated to be an effective pozzolan to improve sulfate resistance of ordinary portland cement (type I. In this paper physico-chemical effects that produce this pozzolan in the mortar exposed to sulfate attack are studied. Dilution and dispersion affects are analyzed using mixes of cement with an inert mineral admixture. Mineralogical changes of mortar are studied using X-ray diffraction and the help of scanning electron microscope. The results show that fly ash delays mortar cracking phenomenon due to less content of unstable compounds in sulfate environment, greater available space to be occupied by expansive compounds and less CH present in the mortars.

    La ceniza volante de bajo contenido de óxido de calcio ha demostrado ser una efectiva puzolana para mejorar la resistencia a los sulfatos del cemento portland normal (CRN. En el presente trabajo se estudian los efectos físico-químicos que produce esta puzolana en el mortero expuesto al ataque de sulfatos. Se analizan los efectos de dilución y dispersión utilizando mezclas de cemento con una adición mineral inactiva. Los cambios mineralógicos del mortero se estudian con difracción de rayos X (DRX y la ayuda del microscopio electrónico. Los resultados indican que la ceniza volante retarda el fenómeno de fisuración del mortero debido a la menor cantidad de compuestos inestables en ambiente con sulfatos, el mayor espacio disponible para albergar a los compuestos expansivos y la disminución del CH presente en la mezcla.

  17. Processo de hidratação e os mecanismos de atuação dos aditivos aceleradores e retardadores de pega do cimento de aluminato de cálcio Hidration process and the mechanisms of retarding and accelerating the setting time of calcium aluminate cement

    OpenAIRE

    Garcia, J. R.; Oliveira, I. R. de; V. C. Pandolfelli

    2007-01-01

    Um dos aspectos principais para o desenvolvimento de concretos refratários está no aprimoramento dos conhecimentos sobre o cimento de alta alumina ou cimento de aluminato de cálcio (CAC), já que esse ligante é o mais utilizado nesta classe de produtos. O objetivo desse trabalho foi o de analisar as informações disponíveis na literatura para se obter um conhecimento mais aprofundado dos mecanismos de ação dos aditivos retardadores e aceleradores da pega deste cimento. Da análise dos dados comp...

  18. EnviroAtlas -Portland, ME- One Meter Resolution Urban Land Cover (2010) Web Service

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas web service supports research and online mapping activities related to EnviroAtlas (https://www.epa.gov/enviroatlas). The Portland, ME land cover...

  19. EnviroAtlas -Portland, ME- One Meter Resolution Urban Land Cover (2010)

    Data.gov (United States)

    U.S. Environmental Protection Agency — The EnviroAtlas Portland, ME land cover map was generated from USDA NAIP (National Agricultural Imagery Program) four band (red, green, blue and near infrared)...

  20. EnviroAtlas - Portland, OR - BenMAP Results by Block Group

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset demonstrates the effect of changes in pollution concentration on local populations in 1176 block groups in Portland, Oregon. The US EPA's...

  1. EnviroAtlas - Portland, ME - BenMAP Results by Block Group

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset demonstrates the effect of changes in pollution concentration on local populations in 146 block groups in Portland, Maine. The US EPA's...

  2. Hydration of Blended Portland Cements Containing Calcium-Aluminosilicate Glass Powder and Limestone

    DEFF Research Database (Denmark)

    Moesgaard, Mette; Poulsen, S.L.; Herfort, D.;

    2012-01-01

    This work investigates the hydration of blended Portland cement containing 30 wt.% Na2O-CaO-Al2O3-SiO2 (NCAS) glass particles either as the only supplementary cementitious material (SCM) or in combination with limestone, using 29Si MAS NMR, powder XRD, and thermal analyses. The NCAS glass...... of hydration. The hydrated glass contributes to the formation of the calcium-silicate-hydrate (C-S-H) phase, consuming a part of the Portlandite (Ca(OH)2) formed during hydration of the Portland cement. Furthermore, the presence of the glass and limestone particles, alone or in combination, results...... in an accelerated hydration for alite (Ca3SiO5), the main constituent of Portland cement. A higher degree of limestone reaction has been observed in the blend containing both limestone and NCAS glass as compared to the limestone – Portland mixture. This reflects that limestone reacts with a part of the alumina...

  3. Sulfatos en el cemento portland y su incidencia sobre el falso fraguado: Estado actual del conocimiento

    Directory of Open Access Journals (Sweden)

    de la Cruz, Ignacio

    1983-12-01

    Full Text Available A bibliographical study is carried out of the sulphates which may be present in the clinker and Portland cement, as likewise the effects of the aeration and temperature on the setting. This work is a prior phase of a wide experimental investigation carried out in the IETCC, on anomalies or setting and phenomena of "lumping" in Portland cement.

    Se realiza un estudio bibliográfico de los sulfatos que pueden estar presentes en el clínker y cemento portland, así como de los efectos de la aireación y temperatura sobre el fraguado. Este trabajo es la fase previa de una amplia investigación experimental realizada en el IETCC, sobre anomalías de fraguado y fenómenos de "aterronamiento" en el cemento portland.

  4. Comparison of the root-end sealing ability of MTA and Portland cement.

    Science.gov (United States)

    Islam, Intekhab; Chng, Hui Kheng; Yap, Adrian U Jin

    2005-08-01

    The aim of this study was to compare the in vitro sealing ability of ProRoot MTA, ProRoot MTA (Tooth-Coloured Formula), ordinary Portland cement and white Portland cement when used as root-end filling materials. Twenty-four single-rooted human premolars were prepared and obturated using standard techniques, then retrofilled with the test materials. The prepared teeth were immersed in 1% methylene blue dye for 72 hours and then assessed for dye leakage. The depth of dye penetration was measured and expressed as a percentage of the length of the retrofilling. Data was analysed using ANOVA and Fisher's Least Significant Test (LSD) (p cements, it is reasonable to consider Portland cement as a possible substitute for MTA as a root-end filling material. However, further tests, especially in vivo biocompatibility tests, need to be conducted before Portland cement can be recommended for clinical use.

  5. Study of thermocycling effect on the bond strength between an aluminous ceramic and a resin cement Estudo do efeito da ciclagem térmica na resistência da união adesiva entre uma cerâmica aluminizada e um cimento resinoso

    Directory of Open Access Journals (Sweden)

    Osvaldo Daniel Andreatta Filho

    2005-03-01

    Full Text Available This study evaluated the effect of thermocycling on the bond strength between Procera AllCeram (Nobel-Biocare and a resin cement (Panavia F, Kuraray CO. Nine ceramic blocks with dimensions of 5x6x6mm were conditioned at one face with Rocatec System (Espe. After, they were luted with Panavia F to composite resin blocks (Clearfil AP-X, Kuraray CO. The nine groups formed by ceramic, cement and composite resin were split up obtaining 75 samples with dimensions of 12x1x1mm and adhesive surface presenting 1mm²±0.1mm² of area. The samples were divided into 3 groups (n=25: G1 - 14 days in distilled water at 37ºC; G2 - 6,000 cycles in water (5ºC - 55ºC - 30s; G3 - 12,000 cycles in water (5ºC - 55ºC - 30s. The samples were tested in a universal testing machine (EMIC at a crosshead speed of 1mm/min. Data were analyzed by ANOVA and Tukey tests. The results indicated that mean values of rupture tension (MPa of G1 (10.71 ± 3.54 did not differ statistically (p Este trabalho avaliou o efeito da ciclagem térmica sobre a resistência adesiva entre a cerâmica aluminizada (Procera AllCeram, Nobel-Biocare e um cimento resinoso (Panavia F, Kuraray CO. Nove blocos de cerâmica, com dimensões de 5x6x6mm, foram condicionados em uma de suas faces com o Sistema Rocatec (ESPE. A seguir foram cimentados a blocos de resina composta (Clearfil AP-X, Kuraray CO. Os conjuntos cerâmica-cimento-resina foram cortados em 75 corpos-de-prova com formato retangular com dimensões de 12x1x1mm e superfície adesiva apresentando 1mm² ± 0,1mm². Os corpos-de-prova foram divididos em três grupos (n=25: G1 - 14 dias em água destilada a 37ºC, G2 - 6000 ciclos em água (5ºC e 55ºC e G3 - 12000 ciclos em água (5ºC e 55ºC. Os corpos-de-prova foram ensaiados sob velocidade de 1mm/min em máquina de ensaio universal (EMIC. Os dados foram tratados estatisticamente com os testes de Anova e Tukey e indicaram que os valores médios de tensão de rupturas (MPa de G1 (10,71 ± 3

  6. Effect of different mixing methods on the physical properties of Portland cement

    OpenAIRE

    Shahi, Shahriar; Ghasemi, Negin; Rahimi, Saeed; Yavari, Hamidreza; Samiei, Mohammad; Jafari, Farnaz

    2016-01-01

    Background The Portland cement is hydrophilic cement; as a result, the powder-to-liquid ratio affects the properties of the final mix. In addition, the mixing technique affects hydration. The aim of this study was to evaluate the effect of different mixing techniques (conventional, amalgamator and ultrasonic) on some selective physical properties of Portland cement. Material and Methods The physical properties to be evaluated were determined using the ISO 6786:2001 specification. One hundred ...

  7. The hardening of Portland cement studied by ? NMR stray-field imaging

    Science.gov (United States)

    Nunes, Teresa; Randall, E. W.; Samoilenko, A. A.; Bodart, P.; Feio, G.

    1996-03-01

    Hydration and hardening processes of Portland cement (type I) were studied by analysis of the one-dimensional projections (profiles) obtained periodically with the 0022-3727/29/3/044/img8 stray-field imaging technique over two days. The influence of additives, such as gypsum, in Portland cement (type IA) was also investigated. The decay of the signal intensity as a function of time was found to be bi-exponential for type I and mono-exponential for type IA.

  8. Evaluation of the radiopacity of root canal sealers by digitization of radiographic images Avaliação da radiopacidade de cimentos endodônticos por meio da digitalização de imagens radiográficas

    Directory of Open Access Journals (Sweden)

    Juliane Maria Guerreiro Tanomaru

    2004-12-01

    Full Text Available The aim of this study was to evaluate the radiopacity of a zinc oxide and eugenol-based (Endofill, a calcium hydroxide-based (Sealapex, two resin-based (Sealer 26 and AH Plus, and a silicone-based root canal sealer (Roeko Seal. Specimens, measuring 10mm in diameter and 1mm in thickness, were radiographed simultaneously with an aluminum step wedge using occlusal films, according to ISO 6876/2001 standards. Radiographs were digitized, and the radiopacity of sealers was compared to the different thicknesses of the aluminum step wedge, using the VIXWIN 2000 software. Results demonstrated that AH Plus was the most radiopaque sealer, while Sealapex was the least radiopaque (pO objetivo deste trabalho foi avaliar a radiopacidade de cimentos endodônticos à base de óxido de zinco e eugenol (Endofill, hidróxido de cálcio (Sealapex, resina (Sealer 26 e AH Plus e silicone (Roeko Seal. Os corpos de prova foram padronizados com 10 milímetros de diâmetro e 1 milímetro de espessura e radiografados conjuntamente com uma escala de alumínio empregando-se filmes oclusais, de acordo com as Normas ISO 6876/2001. As radiografias foram digitalizadas e as radiopacidades dos cimentos comparadas à escala de alumínio com diferentes espessuras, utilizando o software VIXWIN 2000. Os resultados demonstraram que o AH Plus foi o cimento mais radiopaco e o Sealapex apresentou menor radiopacidade (p<0,05, sendo intermediários os resultados para os cimentos Roeko Seal, Endofill e Sealer 26. Sealapex apresenta menor radiopacidade que outros tipos de cimentos endodônticos.

  9. Arsenic content in Portland cement: A literature review

    Directory of Open Access Journals (Sweden)

    Tenorio de Franca Talita

    2010-01-01

    Full Text Available Portland cement (PC is a hydraulic binding material widely used in the building industry. The main interest in its use in dentistry is focused on a possible alternative to mineral trioxide aggregate (MTA because PC is less expensive and is widely available. In dentistry, PC has been used in dental procedures such as pulpotomy, pulp capping, repair of root perforation and root-end filling. The purpose of this article is review the dental literature about the PC, its composition with special attention to arsenic content, properties, and application in dentistry. A bibliographic research was performed in Bireme, PubMed, LILACS and Scopus data bases looking for national and international studies about the PC composition, properties and clinical use. It was observed that PC has favorable biological properties very similar to those of MTA. The PC has shown good cell proliferation induction with formation of a monolayer cell, satisfactory inflammatory response, inhibitory effect of prostaglandin and antimicrobial effect. Studies have shown that PC is not cytotoxic, stimulates the apposition of reparative dentin and permits cellular attachment and growth. Regarding arsenic presence, its levels and release are low. PC has physical, chemical and biological properties similar to MTA. Arsenic levels and release are low, therefore, unable to cause toxic effects.

  10. Stabilization of chromium salt in ordinary portland cement

    Indian Academy of Sciences (India)

    Damir Barbir; Pero Dabić; Petar Krolo

    2012-12-01

    Ordinary Portland cement (OPC) samples containing the chromium salt have been investigated using differential microcalorimetry, conductometry and Fourier transform infrared spectroscopic analysis. The effect of chromium on OPC hydration was evaluated by continuous observing of early hydration. The microcalorimetrical results show that with increasing the share of chromium salt, heat maximums assume lower values and the occurrence of the maximum registered in the earlier hydration times. Conductometrical measurements show that with increasing addition of chromium salt, curve did not show any specific shape, immediate drop in specific conductivity is noticed and the maximum is reached earlier. This coincides with microcalorimetrical results. It can be concluded that the addition of chromium does not affect the mechanism of the hydration process, but it does affect the kinetic parameters and dynamics of the cement hydration process. It was found that chromium salt addition to the cement–water system is acceptable up to 2 wt.%. According to standard EN 196-3 for OPC, the beginning of binding time should occur after 60 minutes. Increased amount of chromium over 2 wt.% significantly accelerate the beginning of binding time and for the system it is not acceptable.

  11. Coprocessamento de cascas de arroz e pneus inservíveis e logística reversa na fabricação de cimento Rice husk and scrap tires co-processing and reverse logistics in cement manufacturing

    Directory of Open Access Journals (Sweden)

    Miguel Afonso Sellitto

    2013-03-01

    Full Text Available O objetivo deste artigo é descrever o caso de um fabricante de cimento que implantou e consolidou o coprocessamento de casca de arroz e de pneus inservíveis em fornos de clínquer, apoiado em práticas de logística reversa, através de estudo de caso como método de pesquisa. A empresa estudada já usava casca de arroz como combustível alternativo e recebeu oferta da indústria de pneumáticos para queima de pneus que não seriam mais aproveitados em fornos de clínquer. Para aproveitar os resíduos, a empresa integrou fluxos diretos e reversos de matéria-prima, combustíveis e resíduos industriais, reduzindo em mais de 30% os custos de transporte. O coprocessamento conjunto substituiu parcialmente combustíveis fósseis originados na indústria petrolífera. O ganho ambiental mais importante foi a redução na queima de cerca de 10 mil toneladas de combustível fóssil, o que acarretava a geração de cerca de 30 mil toneladas de CO2 por ano.El propósito de este artículo es describir el caso de un fabricante de cemento que ha desplegado y consolidado el coprocesamiento de neumáticos inútiles y cascarilla de arroz en hornos de clínker, apoyados en prácticas de logística inversa. El método de investigación fue el estudio de caso. La empresa estudiada ya usaba cascarilla de arroz como combustible alternativo y recibió una oferta de la industria neumática para quema de chatarra de neumáticos en hornos de clínker. Para tomar ventaja de los residuos, la compañía ha integrado los flujos directo e inverso de materias primas, combustibles y residuos industriales, reduciendo los costos de transporte más de 30%. El coprocesamiento reemplazó parcialmente combustibles fósiles obtenidos en la industria petrolera. La ganancia ambiental más importante fue la reducción en la quema de unas 10.000 toneladas de combustibles fósiles, que implica la generación de cerca de 30.000 toneladas de CO2 al año.The purpose of this article is to

  12. Immediate and delayed solubility of mineral trioxide aggregate and Portland cement

    Directory of Open Access Journals (Sweden)

    Augusto Bodanezi

    2008-04-01

    Full Text Available This study investigated the solubility of mineral trioxide aggregate (MTA and Portland cement since its mixture until 672 hours, by means of two complimentary methods. Metal ring molds filled with the cements were covered with distilled water and, at each experimental time (3, 24, 72, 168, 336 and 672 hours, were weighed as soon as the plates in which the samples have been placed. Empty rings served as the control group (n=8. Mean weight gain and loss was determined and analyzed statistically by two-way ANOVA and Tukey's test for all pairwise comparisons. Only Portland cement showed less than 3% weight loss through 24 hours. Detached MTA residues were heavier than those of Portland cement over the 3 to 168 hours. The weight of MTA rings increased more than that of Portland rings within 672 hours (p=0.05. The findings of the present study indicate that, in an aqueous environment MTA is more soluble than Portland cement and exceeds the maximum weight loss considered acceptable by ISO 6876 standard (2001.

  13. Manganese substitutions into the portland cement clinker phases

    Directory of Open Access Journals (Sweden)

    Puertas, F.

    1989-06-01

    Full Text Available The effect of manganese substitution into the crystal structures of the main Portland cement clinker phases (3CaO.SiO2, 2CaO.SiO2, 3CaO.Al2O3, 2CaO.Fe2O3 y 4CaO.Al2O3.Fe2O3 has been studied by X-ray and analytical electron microscopy. In oxidizing conditions, the limit of solid solution in 3CaO.SiO2 is about 0.72 ±0.11% (wt, while in 2CaO.SiO2 is 1.53±0,12%(wt. Mn solid solubility on 3CaO.Al2O3structure, in oxidizing conditions is close to 0.78 ± 0,12% (wt. In identical atmosphere, the proportion of Mn in the ferrite phases (2CaO.Fe2O3 and 4CaO.Al2O3.Fe2O3 is 6.80 ± 0.87% (wt and 6.7% (wt, respectively. To each mentioned clinker phases a solid solution formula has been proposed. In these formula, the manganese substitutions and also the different oxidation states which this element can be introduced in those crystalline structure are defined.

    Se ha estudiado, por difracción de rayos X y microanálisis por espectroscopia de energías dispersivas, el efecto de la sustitución del manganeso en las estructuras cristalinas de las fases más importantes del clinker del cemento portland (3CaO.SiO2, 2CaO.SiO2, 3CaO.Al2O3, 2CaO.Fe2O3 y 4CaO.Al2O3.Fe2O3. En condiciones oxidantes, el límite de solubilidad sólida en 3CaO.SiO2 es del orden de 0,72 ± 0,11% en peso; mientras que en 2CaO.SiO2 es de 1,53 ±0,12% en peso. La solución sólida del Mn en la estructura del 3CaO.Al2O3, en condiciones oxidantes, es próxima al 0,78 ±0,12% en peso. En idéntica atmósfera, la proporción del Mn en las fases terríficas (2CaO.Fe2O3 y 4CaO.Al2

  14. DURABILIDAD DEL CEMENTO PORTLAND BLANCO ADICIONADO CON PIGMENTO AZUL ULTRAMAR

    Directory of Open Access Journals (Sweden)

    CAROLINA GIRALDO

    2010-01-01

    Full Text Available El pigmento Azul Ultramar (AU es un aluminosilicato polisulfurado de sodio que reacciona con el aluminato tricálcico (C3A y con el óxido de calcio (CaO del cemento Pórtland blanco en presencia de agua, generando cantidades considerables de etringita a edad temprana y en menor proporción de tobermorita. Esta etringita primaria se presenta en forma de fibras no orientadas mejorando el desempeño mecánico de los morteros, y al mismo tiempo dejando pocas cantidades de C3A disponible para la formación de etringita secundaria. En esta investigación se evalúa la durabilidad a diferentes edades de curado en morteros de cemento Portland blanco sustituidos por 0%, 10% y 20% de AU en peso, mediante pruebas de succión capilar y evaluación del cambio longitudinal de morteros expuestos a una solución de sulfato de sodio con una concentración del 5% (ASTM C1012. Los resultados evidencian una mayor resistencia a compresión y a flexión, una significativa disminución de la expansión y una reducción hasta del 800% de la absorción de agua en morteros con AU. Todo esto debido a la formación de las fases minerales adicionales (etringita primaria y tobermorita, las cuales fueron identificadas mediante microscopía electrónica de barrido (SEM.

  15. Compósitos à base de cimento reforçados com polpa celulósica de bambu. Parte I: Determinação do teor de reforço ótimo Cement-based composite reinforced with bamboo pulp. Part I: Determination of optimum reinforcement percentage

    Directory of Open Access Journals (Sweden)

    Marcos A. S. dos Anjos

    2003-08-01

    Full Text Available Este trabalho apresenta os resultados experimentais de um estudo em que se procurou desenvolver compósitos de matriz cimentícia reforçada com polpa de bambu. Foram usados dois tipos de polpa: refinada e sem refino. Fez-se variar o teor de fibras de 0 a 16% em massa de cimento e se desenvolveu um processo com sucção, moldagem e prensagem para fabricação dos compósitos. As relações constitutivas dos compósitos foram definidas através de ensaio a compressão e tração de corpos-de-prova cilíndricos de 5x10 cm e do ensaio de flexão em três pontos. A partir delas, foi obtida a capacidade de absorção de energia. Determinaram-se, também, algumas propriedades físicas, como absorção, porosidade aparente, densidade seca e úmida dos compósitos. Os resultados mostraram melhor performance dos compósitos com fibras refinadas em relação àquelas com fibras sem refino e também indicaram que o teor ótimo de fibras refinadas se situou em torno de 8%, quando promoveram notáveis melhoramentos das propriedades mecânicas dos compósitos em relação à matriz plena.This work presents the experimental results of a study which intended to develop a composite with cementations matrix reinforced with bamboo pulp. Two types of pulps were used: refined and unrefined pulps. The fibre content varied between 0 and 16% cement (weight basis. After the preparation of fresh composite mix the experimental specimens were prepared applying a specially developed process based on Hastshek method using suction then moulding and pressing. The compression, tension and the flexural behavior and their constitutive relations were established using 5 cm diameter by 10 cm high cylindrical specimens and three point bending tests at respectively. The energy absorbing capacity of the new composites was also established. Physical properties such as water absorption, apparent porosity, dry and humid density were also obtained. The results showed a better performance

  16. Pulpal response of dogs primary teeth to an adhesive system or to a calcium hydroxide cement Resposta pulpar de dentes decíduos de cães a um sistema adesivo ou ao cimento de hidróxido de cálcio

    Directory of Open Access Journals (Sweden)

    Rosângela Almeida RIBEIRO

    2000-03-01

    de cada cavidade. A hemorragia foi controlada com "bolinhas" de algodão esterilizadas. O esmalte, dentina e local da exposição pulpar de cinco dentes foram condicionados com ácido fosfórico a 35%, seguido da aplicação de um sistema adesivo (Scotchbond Multi-Uso - 3M. Nos outros cinco dentes, um cimento de hidróxido de cálcio (Hydro C - Dentsply foi aplicada no local da exposição pulpar antes da aplicação do mesmo sistema adesivo. Todos os dentes foram restaurados com uma resina composta (Z-100 - 3M. Após 7, 30 ou 45 dias os cães foram anestesiados e perfundidos com solução salina seguida de uma solução de formalina neutra tamponada. A maxila e a mandíbula foram seccionadas em três partes e estocadas em uma solução para desmineralização. Após a desmineralização óssea, todos os dentes foram cortados, incluídos em parafina e seccionados longitudinalmente. A seguir todos os dentes foram corados com hematoxilina e eosina e observados em microscópio de luz. Os resultados demonstraram a presença e persistência de uma resposta inflamatória de diferentes intensidades nos três períodos experimentais. Não houve variação na resposta inflamatória pelos diferentes tratamentos propostos.

  17. Effect of Fine Steel Slag Powder on the Early Hydration Process of Portland Cement

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Hydration heat evolution, non-evaporative water, setting time and SEM tests were performed to investigate the effect of fine steel slag powder on the hydration process of Portland cement and its mechanism.The results show that the effect of fine steel slag powder on the hydration process of Portland cement is closely related to its chemical composition, mineral phases, fineness, etc.Fine steel slag powder retards the hydration of portland cement at early age.The major reason for this phenomenon is the relative high content of MgO , MnO2, P2 O5in steel slag, and MgO solid solved in C3 S contained in steel slag.

  18. High-resolution synchrotron powder diffraction analysis of ordinary Portland cements: Phase coexistence of alite

    Science.gov (United States)

    de la Torre, Ángeles G.; Losilla, Enrique R.; Cabeza, Aurelio; Aranda, Miguel A. G.

    2005-08-01

    The mineralogical composition of four commercial and NIST RM-8488 Portland clinkers have been analysed by Rietveld methodology using high-resolution synchrotron X-ray powder diffraction data. Alite phase coexistence has been observed in four patterns. White Portland clinkers show a single alite or a very small amount of a second alite with smaller volume due to higher magnesium content. Grey Portland clinkers show a much pronounced alite phase coexistence which has been related to higher magnesium contents. Details about these analyses are given. Furthermore, the full mineralogical composition (including the non-diffracting content) has been determined from the overestimation of the added standard, α-Al2O3, in the Rietveld analyses. White clinkers contain ∼15 wt.% of non-diffracting content while this fraction is much smaller in grey clinkers, ∼7 wt.%.

  19. High-resolution synchrotron powder diffraction analysis of ordinary Portland cements: Phase coexistence of alite

    Energy Technology Data Exchange (ETDEWEB)

    Torre, Angeles G. de la [Departamento de Quimica Inorganica, Cristalografia y Mineralogia, Universidad de Malaga, 29071 Malaga (Spain); Losilla, Enrique R. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia, Universidad de Malaga, 29071 Malaga (Spain); Cabeza, Aurelio [Departamento de Quimica Inorganica, Cristalografia y Mineralogia, Universidad de Malaga, 29071 Malaga (Spain); Aranda, Miguel A.G. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia, Universidad de Malaga, 29071 Malaga (Spain)]. E-mail: g_aranda@uma.es

    2005-08-15

    The mineralogical composition of four commercial and NIST RM-8488 Portland clinkers have been analysed by Rietveld methodology using high-resolution synchrotron X-ray powder diffraction data. Alite phase coexistence has been observed in four patterns. White Portland clinkers show a single alite or a very small amount of a second alite with smaller volume due to higher magnesium content. Grey Portland clinkers show a much pronounced alite phase coexistence which has been related to higher magnesium contents. Details about these analyses are given. Furthermore, the full mineralogical composition (including the non-diffracting content) has been determined from the overestimation of the added standard, {alpha}-Al{sub 2}O{sub 3}, in the Rietveld analyses. White clinkers contain {approx}15 wt.% of non-diffracting content while this fraction is much smaller in grey clinkers, {approx}7 wt.%.

  20. Desempenho físico-químico e mecânico de concreto de cimento Portland com borracha de estireno-butadieno reciclada de pneus Physicochemical and mechanical performance of portland cement concrete with recycled styrene-butadiene tyre-rubber waste

    Directory of Open Access Journals (Sweden)

    Camila Freitas

    2009-01-01

    Full Text Available Physicochemical and mechanical techniques were carried out to characterize three concrete tyre-rubber waste dosages such as 5, 10 and 15%, w/w. The elastomeric material was identified as styrene-butadiene rubber (SBR. It was observed that the growing SBR content in the mixture decreased the concrete performance. The best results were presented by 5% w/w tyre-rubber waste concrete sample. This composition was tested at Mourão hydroelectric powerplant spillway as repairing material.

  1. Analysis of Chemical Composition of Portland Cement in Ghana: A Key to Understand the Behavior of Cement

    Directory of Open Access Journals (Sweden)

    Mark Bediako

    2015-01-01

    Full Text Available The performance of Portland cement in concrete or mortar formation is very well influenced by chemical compositions among other factors. Many engineers usually have little information on the chemical compositions of cement in making decisions for the choice of commercially available Portland cement in Ghana. This work analyzed five different brands of Portland cement in Ghana, namely, Ghacem ordinary Portland cement (OPC and Portland limestone cement (PLC, CSIR-BRRI Pozzomix, Dangote OPC, and Diamond PLC. The chemical compositions were analyzed with X-Ray Fluorescence (XRF spectrometer. Student’s t-test was used to test the significance of the variation in chemical composition between standard literature values and each of the commercial cement brands. Analysis of variance (ANOVA was also used to establish the extent of variations between chemical compositions and brand name of the all commercial Portland cement brands. Student’s t-test results showed that there were no significant differences between standard chemical composition values and that of commercial Portland cement. The ANOVA results also indicated that each brand of commercial Portland cement varies in terms of chemical composition; however, the specific brands of cement had no significant differences. The study recommended that using any brand of cement in Ghana was good for any construction works be it concrete or mortar formation.

  2. 76 FR 50252 - Gray Portland Cement and Cement Clinker From Japan; Scheduling of an Expedited Five-Year Review...

    Science.gov (United States)

    2011-08-12

    ... COMMISSION Gray Portland Cement and Cement Clinker From Japan; Scheduling of an Expedited Five-Year Review Concerning the Antidumping Duty Order on Gray Portland Cement and Cement Clinker From Japan AGENCY: United... cement and cement clinker from Japan would be likely to lead to continuation or recurrence of...

  3. Avaliação in vitro da resistência ao cisalhamento e liberação de flúor de dois cimentos de ionômero de vidro reforçado por resina = In vitro evaluation of shear bond strength and fluoride release from two resin-reinforced glass ionomer cements

    Directory of Open Access Journals (Sweden)

    Pithon, Matheus Melo

    2007-01-01

    Full Text Available O objetivo deste estudo foi avaliar os cimentos de ionômero de vidro reforçados com resina Fuji Ortho LC e Fuji Ortho Band (GC América Corporation, Tokyo, Japan quanto a resistência ao cisalhamento e liberação de flúor. Para avaliação da resistência ao cisalhamento utilizou-se 60 incisivos inferiores permanentes bovinos divididos em três grupos (n = 15. No Grupo 1, 2 e 3, as colagens foram realizadas com Transbond XT, Fuji Ortho LC e Fuji Ortho Band respectivamente. Após a colagem realizou-se o ensaio de cisalhamento de toda amostra à velocidade de 0,5 mm por minuto. A liberação de flúor dos materiais foram medidas durante 28 dias (1h, 24 h, 3, 7, 14, 21 e 28 dias através de eletrodo íon seletivo conectado a um analisador de íons. Os resultados demonstraram que quanto a resistência ao cisalhamento (MPa houve diferenças estatísticas entre os grupos 1 e 3, 2 e 3 (p > 0,05. Quanto a liberação de flúor os resultados evidenciaram diferença estatisticamente significante entre os grupos 1 e 3 e 2 e 3 em todos os tempos (p = 0. 00 e entre os grupos 1 e 2 na avaliação de 3 dias de liberação de flúor (p = 0. 00. Baseado nos resultados obtidos conclui-se que os materiais Transbond XT e Fuji Ortho possuem melhor resistência ao cisalhamento porém menor liberação de flúor quando comparado ao Fuji Ortho Band

  4. Hydration of Blended Portland Cements Containing Calcium-Aluminosilicate Glass Powder and Limestone

    DEFF Research Database (Denmark)

    Moesgaard, M; Poulsen, Søren Lundsted; Herfort, D;

    2012-01-01

    M. MOESGAARD, S.L. POULSEN, D. HERFORT, M. STEENBERG, L.F. KIRKEGAARD, J. SKIBSTED, Y. YUE, Hydration of Blended Portland Cements Containing Calcium-Aluminosilicate Glass Powder and Limestone, Journal of the American Ceramic Society 95, 403 – 409 (2012).......M. MOESGAARD, S.L. POULSEN, D. HERFORT, M. STEENBERG, L.F. KIRKEGAARD, J. SKIBSTED, Y. YUE, Hydration of Blended Portland Cements Containing Calcium-Aluminosilicate Glass Powder and Limestone, Journal of the American Ceramic Society 95, 403 – 409 (2012)....

  5. Portland cement hydration in the presence of admixtures: black gram pulse and superplasticizer

    Directory of Open Access Journals (Sweden)

    Viveka Nand Dwivedi

    2008-12-01

    Full Text Available Effect of admixtures such as black gram pulse (BGP and sulfonated naphthalene based superplasticizer (SP on the hydration of Portland cement has been studied. The hydration characteristics of OPC in the presence of BGP and SP were studied with the help of non evaporable water content determinations, calorimetric method, Mössbauer spectroscopic and atomic force microscopic techniques. Results have shown that both BGP and SP get adsorbed at the surface of cement and its hydration products. The hydration of Portland cement is retarded in the presence of both the admixtures and nanosize hydration products are formed.

  6. Clinical evaluation of glass-ionomer cement restorations Avaliação clínica de restaurações de cimento de ionômero de vidro

    Directory of Open Access Journals (Sweden)

    Martin John Tyas

    2006-01-01

    Full Text Available This article mentions the general structure, properties and clinical performance of conventional and resin-modified glass-ionomer cements, focusing on adhesion, caries inhibition effect and recommendations of their use.Este artigo menciona a estrutura geral, propriedades e performance clínica de cimentos de ionômero de vidro convencionais e modificados por resina, enfocando propriedades como adesão, efeito anti-cariogênico e recomendações de uso.

  7. Clinical evaluation of glass-ionomer cement restorations Avaliação clínica de restaurações de cimento de ionômero de vidro

    OpenAIRE

    Martin John Tyas

    2006-01-01

    This article mentions the general structure, properties and clinical performance of conventional and resin-modified glass-ionomer cements, focusing on adhesion, caries inhibition effect and recommendations of their use.Este artigo menciona a estrutura geral, propriedades e performance clínica de cimentos de ionômero de vidro convencionais e modificados por resina, enfocando propriedades como adesão, efeito anti-cariogênico e recomendações de uso.

  8. Evaluation of flood inundation in Crystal Springs Creek, Portland, Oregon

    Science.gov (United States)

    Stonewall, Adam; Hess, Glen

    2016-05-25

    Efforts to improve fish passage have resulted in the replacement of six culverts in Crystal Springs Creek in Portland, Oregon. Two more culverts are scheduled to be replaced at Glenwood Street and Bybee Boulevard (Glenwood/Bybee project) in 2016. Recently acquired data have allowed for a more comprehensive understanding of the hydrology of the creek and the topography of the watershed. To evaluate the impact of the culvert replacements and recent hydrologic data, a Hydrologic Engineering Center-River Analysis System hydraulic model was developed to estimate water-surface elevations during high-flow events. Longitudinal surface-water profiles were modeled to evaluate current conditions and future conditions using the design plans for the culverts to be installed in 2016. Additional profiles were created to compare with the results from the most recent flood model approved by the Federal Emergency Management Agency for Crystal Springs Creek and to evaluate model sensitivity.Model simulation results show that water-surface elevations during high-flow events will be lower than estimates from previous models, primarily due to lower estimates of streamflow associated with the 0.01 and 0.002 annual exceedance probability (AEP) events. Additionally, recent culvert replacements have resulted in less ponding behind crossings. Similarly, model simulation results show that the proposed replacement culverts at Glenwood Street and Bybee Boulevard will result in lower water-surface elevations during high-flow events upstream of the proposed project. Wider culverts will allow more water to pass through crossings, resulting in slightly higher water-surface elevations downstream of the project during high-flows than water-surface elevations that would occur under current conditions. For the 0.01 AEP event, the water-surface elevations downstream of the Glenwood/Bybee project will be an average of 0.05 ft and a maximum of 0.07 ft higher than current conditions. Similarly, for the 0

  9. Use of copper slag in the manufacture of Portland cement

    Directory of Open Access Journals (Sweden)

    Aquilar Elguézabal, A.

    2006-03-01

    Full Text Available Given its chemical and mineralogical characteristics, copper slag, a solid industrial by-product, may serve as a partial substitute for silica and hematite in raw mixes used to manufacture Portland cement clinker. The benefits of such substitution include lower production costs and energy savings. The effect of slag-containing raw mixes on the reactivity of the CaO-Si02-Al203-Fe203 system was studied at three temperatures (1,350, 1,400 and 1,450ºC. Four mixes were used: M-1 and M-2 prepared with conventional prime materials and M-3 and M-4, in which ignimbrite and hematite were substituted for slag. In M-3 the slag replaced 45.54% of the ignimbrite and 100% of the hematite, and in M-4 100% of the mineral iron. The samples were clinkerized at 1,350, 1,400 and 1,450ºC. At 1,400ºC, clinker M-3 was found to have 10.7% less free lime than M-1, while the level in M-4 it was 15.93% lower than in M-2. The presence of the main clinker phases was confirmed by X-ray diffraction, which also showed that adding slag during c/inker manufacture slightly improves raw mix burnability without generating new unwanted phases. Consequently, recovery in cement kilns would appear to be an economically and environmentally feasible alternative to coprocessing such waste, although the industrial use of slag depends on its heavy metal content.En acuerdo con las características químicas y mineralógicas de la escoria de cobre, este residuo sólido industrial puede ser utilizado en el proceso de fabricación de clínker Portland como sustituto parcial de los minerales de sílice y hematita en la formación de mezclas crudas cuyos beneficios serían: disminución de los costos de producción de mezclas crudas y del consumo calorífico. El efecto de la adición de la escoria en las mezclas crudas sobre la reactividad del sistema CaO-Si02-Al203-Fe20 3 se estudió en tres niveles de temperatura (1.350, 1.400 Y 1.450ºC. Se trabajó con cuatro mezclas crudas, M-1 y M

  10. Steel foundry electric arc furnace dust management: stabilization by using lime and Portland cement.

    Science.gov (United States)

    Salihoglu, Guray; Pinarli, Vedat

    2008-05-30

    The purpose of this study was to determine an appropriate treatment for steel foundry electric arc furnace dust (EAFD) prior to permanent disposal. Lime and Portland cement (PC)-based stabilization was applied to treat the EAFD that contains lead and zinc above the landfilling limits, and is listed by USEPA as hazardous waste designation K061 and by EU as 10 02 07. Three types of paste samples were prepared with EAFD content varying between 0 and 90%. The first type contained the EAFD and Portland cement, the second contained the EAFD, Portland cement, and lime, and the third contained the EAFD and lime. All the samples were subjected to toxicity characteristics leaching procedure (TCLP) after an air-curing period of 28 days. pH changes were monitored and acid neutralization capacity of the samples were examined. Treatment effectiveness was evaluated in terms of reducing the heavy metal leachability to the levels below the USEPA landfilling criteria. An optimum composition for the EAFD stabilization was formulated as 30% EAFD +35% lime +35% Portland cement to achieve the landfilling criteria. The pH interval, where the solubility of the heavy metals in the EAFD was minimized, was found to be between 8.2 and 9.4.

  11. Microstructure engineering of Portland cement pastes and mortars through addition of ultrafine layer silicates

    DEFF Research Database (Denmark)

    Lindgreen, Holger; Geiker, Mette; Krøyer, Hanne;

    2008-01-01

    Pozzolanic submicron-sized silica fume and the non-pozzolanic micron- and nano-sized layer silicates (clay minerals) kaolinite, smectite and palygorskite have been used as additives in Portland cement pastes and mortars. These layer silicates have different particle shape (needles and plates), su...

  12. Prediction of compressive strength up to 28 days from microstructure of Portland cement

    DEFF Research Database (Denmark)

    Svinning, K.; Høskuldsson, Agnar; Justnes, H.

    2008-01-01

    The influence of the characteristics or the microstructure of Portland cement on compressive strength up to 28 days has been statistically investigated by application of partial least square (PLS) analysis. The main groups of characteristics were mineralogy and superficial microstructure represen...

  13. Prediction of potential compressive strength of Portland clinker from its mineralogy

    DEFF Research Database (Denmark)

    Svinning, K.; Høskuldsson, Agnar; Justnes, H.

    2010-01-01

    Based on a statistical model first applied for prediction of compressive strength up to 28 d from the microstructure of Portland cement, potential compressive strength of clinker has been predicted from its mineralogy. The prediction model was evaluated by partial least squares regression. The mi...

  14. Clients' Experience with Vouchered On-The-Job Training in the Portland Win Program.

    Science.gov (United States)

    Wulf, Douglas; And Others

    From 1974 through 1976, a program to test the feasibility of vouchering manpower training was incorporated into the existing Work Incentive (WIN) program in Portland, Oregon. The purpose of the second phase of the program was to evaluate the feasibility of incorporating vouchers into an on-the-job (OJT) program as an optional component that…

  15. 33 CFR 80.115 - Portland Head, ME to Cape Ann, MA.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Portland Head, ME to Cape Ann, MA. 80.115 Section 80.115 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY..., MA. (a) Except inside lines specifically described in this section, the 72 COLREGS shall apply on...

  16. Physical and Thermodynamical Properties of Water Phases in Hardening Portland Cement Systems

    DEFF Research Database (Denmark)

    Hansen, T. Bæk

    The present study is devoted to the description of water phases in hardening portland cement paste systems containing a significant amount of micro-filler and having a low to moderate water/powder ratio. Emphasis has been placed on the early stages of the hardening process....

  17. Pulp tissue response to Portland cement associated with different radio pacifying agents on pulpotomy of human primary molars.

    Science.gov (United States)

    Marques, N; Lourenço Neto, N; Fernandes, A P; Rodini, C; Hungaro Duarte, M; Rios, D; Machado, M A; Oliveira, T

    2015-12-01

    The objective of this research was to evaluate the response of Portland cement associated with different radio pacifying agents on pulp treatment of human primary teeth by clinical and radiographic exams and microscopic analysis. Thirty mandibular primary molars were randomly divided into the following groups: Group I - Portland cement; Group II - Portland cement with iodoform (Portland cement + CHI3 ); Group III - Portland cement with zirconium oxide (Portland cement + ZrO2 ); and treated by pulpotomy technique (removal of a portion of the pulp aiming to maintain the vitally of the remaining radicular pulp tissue using a therapeutic dressing). Clinical and radiographic evaluations were recorded at 6, 12 and 24 months follow-up. The teeth at the regular exfoliation period were extracted and processed for histological analysis. Data were tested using statistical analysis with a significance level of 5%. The microscopic findings were descriptively analysed. All treated teeth were clinically and radiographically successful at follow-up appointments. The microscopic analysis revealed positive response to pulp repair with hard tissue barrier formation and pulp calcification in the remaining roots of all available teeth. The findings of this study suggest that primary teeth pulp tissue exhibited satisfactory biological response to Portland cement associated with radio pacifying agents. However, further studies with long-term follow-up are needed to determine the safe clinical indication of this alternative material for pulp therapy of primary teeth.

  18. Effects of Thaumasite Formation on the Performance of Portland-limestone Concrete Stored in Magnesium Sulfate Solution

    Institute of Scientific and Technical Information of China (English)

    GAO Lixiong; YAO Yan; WANG Ling

    2005-01-01

    The influence of thaumasite formation on the performance of Portland- limestone cement concrete stored in magnesium sulfate solution was studied. The experimental results show that the deterioration of Portlandlimestone cement concrete is higher than that of Portland cement concrete. The more the content of limestone, the more serious the deterioration of concrete, and also the lower the temperature, the earlier the deterioration of concrete. Thaumasite was detected to form in the Portland-limestone pastes when stored in 10wt% MgSO4 solution at 3- 10 ℃ and it was easy to form at lower temperatures.

  19. Contribución al estudio de los reacciones de hidratación del cemento portland por espectroscopia infrarroja II. Estudio de clínkeres y de cementos portland anhidros

    Directory of Open Access Journals (Sweden)

    Vázquez-Moreno, Tomás

    1976-06-01

    Full Text Available Not availableEn un artículo anterior (1 se dio cuenta de los trabajos realizados sobre la aplicación de la espectroscopia IR al estudio de las principales fases sintetizadas del clínker de cemento portland como fase previa al estudio de diversos clínkeres, obtenidos por nosotros en el laboratorio a partir de crudos industriales, y de distintos cementos portland comerciales anhidros.

  20. Use of thermodynamic chemical potential diagrams (µCaO, µCO2 to understand the weathering of cement by a slightly carbonated water Uso de diagramas de potencial químico termodinâmico (µCaO, µCO2 para o entendimento da resistência do cimento à água levemente carbonatada

    Directory of Open Access Journals (Sweden)

    A. Blandine

    2008-09-01

    Full Text Available Cement is a ubiquitous material that may suffer hazardous weathering. The chemical weathering of cement in natural environment is mostly characterized by the leaching of CaO and the addition of CO2. The different weathering zones that develop at the expense of the cement may be predicted by the help of chemical potential phase diagrams; these diagrams simulate the behaviour of systems open to some chemical elements. Some components have a so-called inert status, that is to say the system is closed for these components, their amount in the system remains constant; some other components have a mobile status, that is to say these components can be exchanged with the outside of the system, their amount can vary from one sample zone to another. The mobile components are represented in the model by their chemical potentials (linked to their concentrations that are variable in the external environment. The main features of the weathering of a cement system open to CaO and CO2 are predicted in a phase diagram with µCaO et µCO2 as diagram axes. From core to rim, one observes the disappearance of portlandite, ettringite and calcium monosulfoaluminate, the precipitation of calcite and amorphous silica, the modification of the composition of the CSH minerals (hydrated calcium silicates that see a decrease of their c/s ratio (CaO/SiO2 from the core to the rim of the sample. For the CSH minerals, we have separated their continuous solid solution into three compositions defined by different CaO/SiO2 ratios and called phases 1, 2 and 3: CaO = 0.8, 1.1, 1.8 respectively for one mole of SiO2 knowing that H2O varies in the three compositions.Cimento é um material de ampla utilização que pode ser sujeito a modificação pelo tempo. A modificação química do cimento em meio natural é principalmente caracterizada por lixiviação de CaO e adição de CO2. As diferentes zonas de resistência que se desenvolvem às custas do cimento podem ser previstas com os

  1. Galvanic corrosion of Mg-Zr fuel cladding and steel immobilized in Portland cement and geopolymer at early ages

    Science.gov (United States)

    Rooses, Adrien; Lambertin, David; Chartier, David; Frizon, Fabien

    2013-04-01

    Galvanic corrosion behaviour of Mg-Zr alloy fuel cladding and steel has been studied in Ordinary Portland cement and Na-geopolymer. Portland cements implied the worse magnesium corrosion performances due to the negative effects of cement hydrates, grinding agents and gypsum on the galvanic corrosion. Galvanic corrosion in Na-geopolymer paste remains very low. Silicates and fluoride from the geopolymer activation solution significantly improve the corrosion resistance of the magnesium alloy while coupling with a cathode.

  2. Ação sonoquímica e influência das condições de tratamento térmico na preparação de cimentos do sistema binário CaO-Al2O3 Sonochemical action and the influence of heat treatment conditions on the preparation of cements of the CaO-Al2O3 binary system

    Directory of Open Access Journals (Sweden)

    R. R Lourenço

    2010-03-01

    Full Text Available Foram preparados cimentos do sistema binário CaO-Al2O3 por meio de uma rota que emprega o processo sonoquímico seguido de tratamento térmico. Convencionalmente estes compostos são fabricados a partir da fusão ou da sinterização de uma mistura de calcário com bauxito ou com alumina. O maior inconveniente associado a este tipo de síntese é a necessidade de temperaturas elevadas e o grande consumo de energia. Na rota sonoquímica a cálcia, juntamente com a alumina em suspensão aquosa, são introduzidas num banho de ultra-som por tempo determinado. Em seguida, após a evaporação da água, o material resultante é tratado termicamente. Quando um sistema é submetido ao processo sonoquímico, alterações na morfologia superficial das partículas podem ser induzidas pelas ondas ultra-sônicas, incluindo a redução do tamanho dessas partículas. Como conseqüência, estes materiais tornam-se mais reativos, facilitando a síntese final dos aluminatos de cálcio durante o tratamento térmico. Foi estudada a ação das ondas ultra-sônicas e a influência das condições de tratamento térmico em duas composições molares de cálcia:alumina de 1:1 e 1:2. As temperaturas empregadas foram 1000 ºC, 1200 ºC e 1300 ºC com patamares de 1 e 6 h. O material obtido foi caracterizado por microscopia eletrônica de varredura, difração de raios X e as fases presentes foram semi-quantificadas pelo método de Rietveld. Também foram realizados ensaios de compressão diametral para avaliar a resistência mecânica dos produtos da síntese. Foram preparadas pastas constituídas de cimento, alumina e água, utilizando como cimento os aluminatos de cálcio preparados pelo processo sonoquímico e um cimento comercial, como referência.Cements of the CaO-Al2O3 binary system were prepared through a sonochemical process at room temperature followed by heat treatment. The conventional production consists of a reaction in which a stoichiometric mixture of

  3. Adição de cimento de aluminato de cálcio e seus efeitos na hidratação do óxido de magnésio Effects of calcium aluminate cement addition on magnesia hydration

    Directory of Open Access Journals (Sweden)

    R Salomão

    2010-06-01

    Full Text Available Cimento de aluminato de cálcio (CAC e óxido de magnésio (MgO são duas importantes matérias primas para a indústria de concretos refratários e apresentam grande tendência à hidratação. Os efeitos dessa reação em cada caso isolado são distintos e bem conhecidos: enquanto o CAC hidratado atua como ligante e garante a resistência mecânica do material antes da sinterização, a hidratação do MgO pode causar sua total desintegração em alguns casos. Devido ao interesse tecnológico nesses materiais, é importante investigar as peculiaridades desses processos e as potenciais interações entre eles. Neste trabalho, os efeitos da adição de diferentes teores de CAC na hidratação do MgO foram investigados em suspensões aquosas usando medidas de expansão volumétrica aparente, pH das suspensões e difração de raios X. Foi observado que os efeitos danosos da hidratação do MgO podem ser significativamente reduzidos com um controle adequado do teor de CAC nas formulações.Calcium aluminate cement (CAC and magnesium oxide (MgO are two of the most important raw materials for refractory castables industry and both present a high driving force for hydration. The effects of this reaction for each compound are well known: whereas the hydrated CAC behaves as a binder, hardening the castable, MgO hydration can cause the total disintegration of the material. Due to the technological interests involved, it is important to study the peculiarities in these processes and their potential interactions. In the present work, the effects of the addition of different CAC contents on MgO hydration were investigated in aqueous suspensions by means of apparent volumetric expansion, pH measurements and qualitative X-ray diffraction. It was found out that the deleterious effects of MgO hydration can be significantly reduced with a proper control of the CAC content for the formulations.

  4. Energy conservation choices for the City of Portland, Oregon: energy information retrieval system. Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    1980-07-01

    Volume 2 sets forth and describes the developmental history as well as the technical accomplishment and design of the non-computerized information retrieval system realized under the aegis of the Portland Energy Conservation Demonstration Project (PECDP). An optical coincidence mechanism, a thesaurus, and an indexing procedure which combine to yield a method to selectively store and retrieve discriminate information in such a fashion whereby that information is readily available in a format acceptable to local government decision makers, the City's capital budgeting process, planning agency personnel, and citizens are described. PECDP's Energy Information Retrieval System was housed in existing library space of the Portland Bureau of Planning and since its establishment, there has been a 500% increase in library use among Planning staff. (MCW)

  5. The Property of Portland Cement and its Employment in Dentistry: Review of the Literature

    Directory of Open Access Journals (Sweden)

    Antonio Vinícius Holanda BARBOSA

    2007-03-01

    Full Text Available Objective: The aim of the present study was to investigate the performance of the Portland cement when used as material in the dentistry. Methods: It was accomplished a bibliographical research using scientific goods published in national and international literature, which intended to evaluate the physical properties, chemical and biological behavior, as well as the antimicrobial activity of this product. In the selected article, the authors used methods of investigation in vitro and in vivo for study comparing the cement with materials consecrated in dentistry. Conclusion: In agreement with the consulted bibliography it was possible to ensure the similarity in the chemical composition between the Portland cement and the MTA, in the effectiveness of the sealing ability of the roads areas between the root canal and the periodontal tissue, satisfactory antimicrobial action, and demonstrate favorable biological properties, stimulating the deposition of the cement and inducing the reparative pulpar answer.

  6. Self-service fare collection on buses in Portland, Oregon. Final report, Septtember 1980-April 1984

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, D.; Harper, W.; Schueftan, O.

    1986-09-01

    In 1980, the Urban Mass Transportation Administration (UMTA) awarded grants to the Tri-County Metropolitan Transportation District (TRI-MET) to implement self-service fare collection (SSFC) on its bus system. TRI-MET, the transit authority serving Portland, Oregon, is the second authority in the United States to use SSFC and the first to use it on buses. TRI-MET expected SSFC to improve bus productivity, facilitate distance-based fares, and reduce fare evasion. Problems encountered with SSFC on buses in Portland included increased fare evasion, high enforcement costs, no productivity improvements, low surcharge/ fine collections, overburdened courts, and increased vandalism. These problems need to be overcome before SSFC can be successful on buses in other U.S. cities.

  7. Inspection of surveillance activities and administrative leave policy at Bonneville Power Administration, Portland, Oregon

    Energy Technology Data Exchange (ETDEWEB)

    1994-04-01

    The authors conducted an inspection of surveillance activities and administrative leave policy at the Bonneville Power Administration, Portland, Oregon. The purpose of their inspection was to determine if a covert video surveillance operation conducted at Bonneville Power Administration was consistent with Department of Energy policies and procedures and other applicable regulations and procedures, and to determine if administrative leave policies and procedures used at Bonneville Power Administration in a specific instance were consistent with Department of Energy requirements and the Code of Federal Regulations. This inspection focused on a specific incident that occurred in 1989 on the 5th floor of the BPA Headquarters Building located in Portland, Oregon. The incident involved the soiling of an employee`s personal property with what appeared to be urine.

  8. Anti-Crack Performance of Low-Heat Portland Cement Concrete

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The properties of low-heat Portland cement concrete(LHC) were studied in detail. The experimental results show that the LHC concrete has characteristics of a higher physical mechanical behavior, deformation and durability. Compared with moderate-heat Portland cement(MHC), the average hydration heat of LHC concrete is reduced by about 17.5%. Under same mixing proportion, the adiabatic temperature rise of LHC concrete was reduced by 2℃-3℃,and the limits tension of LHC concrete was increased by 10×10-6-15×10-6 than that of MHC. Moreover, it is indicated that LHC concrete has a better anti-crack behavior than MHC concrete.

  9. Performance Characteristics of Waste Glass Powder Substituting Portland Cement in Mortar Mixtures

    Science.gov (United States)

    Kara, P.; Csetényi, L. J.; Borosnyói, A.

    2016-04-01

    In the present work, soda-lime glass cullet (flint, amber, green) and special glass cullet (soda-alkaline earth-silicate glass coming from low pressure mercury-discharge lamp cullet and incandescent light bulb borosilicate glass waste cullet) were ground into fine powders in a laboratory planetary ball mill for 30 minutes. CEM I 42.5N Portland cement was applied in mortar mixtures, substituted with waste glass powder at levels of 20% and 30%. Characterisation and testing of waste glass powders included fineness by laser diffraction particle size analysis, specific surface area by nitrogen adsorption technique, particle density by pycnometry and chemical analysis by X-ray fluorescence spectrophotometry. Compressive strength, early age shrinkage cracking and drying shrinkage tests, heat of hydration of mortars, temperature of hydration, X-ray diffraction analysis and volume stability tests were performed to observe the influence of waste glass powder substitution for Portland cement on physical and engineering properties of mortar mixtures.

  10. Effect of superplasticizers on the hydration kinetic and mechanical properties of Portland cement pastes

    Directory of Open Access Journals (Sweden)

    Safaa M.A. El-Gamal

    2012-04-01

    Full Text Available Hydration of ordinary Portland cement in the presence of two different types of superplasticizers namely sodium lignosulfonate (LS and naphthalene sulfonate-formaldehyde condensate (NSF was studied using different experimental techniques. Superplasticized ordinary Portland cement pastes were prepared using the values of standard water of consistency with different additions of each type of superplasticizers used. Pastes were hydrated for different time intervals under normal curing conditions. The results reveal that both superplasticizers increase the workability and reduce the standard water of consistency. This results in an improvement in the mechanical properties of superplasticized cement pastes at all ages of the hydration–hardening process. Naphthalene sulfonate-formaldehyde condensate was found to have the higher efficiency in improving the mechanical properties of the hardened pastes than that of sodium lignosulfonate superplasticizer.

  11. Mechanical properties of Portland cement and its constituents at the nano-level

    Science.gov (United States)

    French, Brent Alexander

    The following is a summary of research for a portion of the project titled Nano to Continuum Multi-Scale Modeling Techniques and Analysis For Cementitious Materials Under Dynamic Loading in association with North Carolina Agricultural & Technical State University and the US Army. This research investigates several attempts at creating a better Portland cement model at the atomistic level through molecular dynamics simulations. These models are modified to simulate damage to the basic cement structure, and are simulated using several combinations of forcefields and molecular dynamics tools. Experimental techniques such as nanoindentation, atomic force microscopy, and x-ray diffraction are applied to Portland cement samples to correlate mechanical properties among these techniques, as well as the numerical simulations.

  12. Hydration Study of Ordinary Portland Cement in the Presence of Lead(II) Oxide

    OpenAIRE

    Barbir, D.; Dabić, P.; Krolo, P.

    2013-01-01

    The aim of this work was to investigate the effect of the addition of lead(II) oxide on hydration heat and specific conductivity of a CEM I Portland cement. The heat released during hydration was determined by differential microcalorimetry up to 48 hours of hydration and the specific conductivity by a digital conductometer. Thermogravimetric analysis was employed in the characterization of the cement structure. The hydration heat results show that the addition of lead(II) oxide affects the...

  13. The influence of clay additives in Portland cement on the compressive strength of the cement stone

    Directory of Open Access Journals (Sweden)

    A.R. Gaifullin

    2015-11-01

    Full Text Available The introduction of mineral additives to binders, especially to Portland cement, is one of the promising trends for solving the resource and energy saving problems, as well as problems of environmental protection during production and application. Expanding the supplementary cementitious materials resource base can be achieved through the use of natural pozzolans and thermally activated polymineral clays(commonly known as glinites in Russia. One type of glinite is metakaolin, which is obtained by calcination of kaolin clays. Metakaolin is widely and effectively used as a pozzolanic additive due to its beneficial effect on the physical and mechanical properties of Portland cement-based materials. The obstacle to its wide production and use are the limited deposits of pure kaolin clays in many countries, including the Russian Federation. In this respect, the studies of pozzolanic activity of the most common mineral clays and their use in some countries have significantly advanced. Similar studies were widely performed in the 1940s in USSR. It seems reasonable to renew this trend to provide a scientific base for the production of local pozzolans made of clays commonly used in different regions. Comparative studies of the effect of 5 clays differing in mineral and chemical composition, calcination temperature and specific surface area, and high-quality metakaolin, on the strength of hardened Portland cement paste have been performed. It has been established that introducing 5…10 % of composite clays calcined at 400…8000 C° and milled to a specific surface area of 290…800 m2/kg into Portland cement enhanced the strength of the hardened cement paste considerably better than the introduction of metakaolin with a specific surface area of 1200 m2/kg. The findings of the study suggest that many kinds of commonly used polymineral clays have a specific calcination temperature and dispersity, which results in a higher pozzolanic activity compared with

  14. Effects of Using Pozzolan and Portland Cement in the Treatment of Dispersive Clay

    OpenAIRE

    Vakili, A. H.; Selamat, M. R.; H. Moayedi

    2013-01-01

    Use of dispersive clay as construction material requires treatment such as by chemical addition. Treatments to dispersive clay using pozzolan and Portland cement, singly and simultaneously, were carried out in this study. When used alone, the optimum amount of pozzolan required to treat a fully dispersive clay sample was 5%, but the curing time to reduce dispersion potential, from 100% to 30% or less, was 3 month long. On the other hand, also when used alone, a 3% cement content was capable o...

  15. Comparative Analysis of Selected Physicochemical Properties of Pozzolan Portland and MTA-Based Cements

    OpenAIRE

    Dorileo, Maura Cristiane Gonçales Orçati; Villa, Ricardo Dalla; Guedes, Orlando Aguirre; Aranha, Andreza Maria Fábio; Semenoff-Segundo, Alex; Bandeca, Matheus Coelho; Borges, Alvaro Henrique

    2014-01-01

    Physicochemical properties of pozzolan Portland cement were compared to ProRoot MTA and MTA BIO. To test the pH, the samples were immersed in distilled water for different periods of time. After the pH analysis, the sample was retained in the plastic recipient, and the electrical conductivity of the solution was measured. The solubility and radiopacity properties were evaluated according to specification 57 of the American National Standard Institute/American Dental Association (ANSI/ADA). Th...

  16. Feasibility study of the Portland cement industry waste for the reduction of energy consumption

    Energy Technology Data Exchange (ETDEWEB)

    Bernardo, Ana Carla de Souza Masselli; Junqueira, Mateus Augusto F. Chaib; Jorge, Ariosto Bretanha; Silva, Rogerio Jose da [Universidade Federal de Itajuba (UNIFEI), MG (Brazil). Institute of Mechanical Engineering]. E-mails: anacarlasz@unifei.edu.br; mateus_afcj@yahoo.com.br; ariosto.b.jorge@unifei.edu.br; rogeriojs@unifei.edu.br

    2008-07-01

    The Portland cement industry demand a high specific consumption of energy for the production of the clinker. The energy consumption for clinker production varies between 3000 and 5300 kJ/kg of produced clinker. The clinker is produced by blending of different raw materials in order t o achieve precise chemical proportions of lime, silica, alumina and iron in the finished product and by burning them at high temperatures. The Portland cement is a mixture of clinker, gypsum and other materials. Due to need of high temperatures, tradition ally the fuels used in the cement industry are mineral coal, fuel oil, natural gas and petroleum coke. The fuel burning in high temperature leads to the formation of the pollutant thermal NOx. The level of emissions of this pollutant is controlled by environmental law, thus the formation of pollutants in process need be controlled. Moreover, industrial waste has been used by Portland cement industries as a secondary fuel through a technique called co -processing. Materials like waste oils, plastics, waste tyres and sewage sludge are often proposed as alternative fuels for the cement industry. The residues can be introduced as secondary fuel or secondary raw material. For energy conservation in the process, mineralizers are added during the process production of the clinker. The mineralizers promote certain reactions which decrease the temperature in the kiln and improve the quality of the clinker. The adequate quantity of constituents in production process is complex, for maintain in controlled level, the quality of final product, the operational conditions of kiln, and the pollutant emissions. The purpose of the present work is to provide an analysis of an optimal production point through of the optimization technique considering, the introduction of the fuels, industrial wastes as secondary fuels, and raw materials, for the reduction of energy in the process of Portland cement production. (author)

  17. Portland cement hydration in the presence of admixtures: black gram pulse and superplasticizer

    OpenAIRE

    Viveka Nand Dwivedi; Shiva Saran Das; Nakshatra Bahadur Singh; Sarita Rai; Namdev Shriram Gajbhiye

    2008-01-01

    Effect of admixtures such as black gram pulse (BGP) and sulfonated naphthalene based superplasticizer (SP) on the hydration of Portland cement has been studied. The hydration characteristics of OPC in the presence of BGP and SP were studied with the help of non evaporable water content determinations, calorimetric method, Mössbauer spectroscopic and atomic force microscopic techniques. Results have shown that both BGP and SP get adsorbed at the surface of cement and its hydration products. Th...

  18. Substitution of the clayey mineral component by lignite fly ash in portland cement clinker synthesis

    Directory of Open Access Journals (Sweden)

    Jovanović Nataša

    2006-01-01

    Full Text Available Fly ash from four power plants in Serbia (PP "Morava" - Svilajnac, PP "Kolubara" - Veliki Grijani, PP "Kostolac" - units B1 and B2 - Kostolac and PP "Nikola Tesla" - units A and B - Obrenovac was utilized as the starting raw component for Portland cement clinker synthesis. Limestone and quartz sand from the "Holcim - Serbia, a.d." cement factory were the other two starting raw components. Based on the chemical composition of the raw components and from the projected cement moduli, the amounts of raw components in the raw mixtures were calculated. Six different raw mixtures were prepared - each one consisted of limestone, sand and different fly ash. A raw mixture from the industrial production of the "Holcim - Serbia, a.d." cement factory was used as the reference material. The prepared raw mixtures were sintered in a laboratory furnace at 1400°C. The chemical and mineralogical compositions of the synthesized clinkers were determined. The characteristics of clinkers, based on fly ash, were compared to the characteristics of the industrial Portland cement clinker from the "Holcim - Serbia, a.d." cement factory. The results of the investigation showed that fly ash from power plants in Serbia can be suitable for Portland cement clinker synthesis.

  19. HYDRATING CHARACTERISTICS OF MODIFIED PORTLAND WITH Ba-BEARING SULPHOALUMINATE MINERALS

    Directory of Open Access Journals (Sweden)

    Chenchen Gong

    2016-03-01

    Full Text Available The hydrating characteristics of modified Portland cement with Ba-bearing sulphoaluminate minerals were studied in this paper. Scanning Electron Microscopy-Energy Dispersive Spectrometer (SEM-EDS, mercury intrusion porosimeter (MIP and compressive strength were determined to characterize hydrating products and microstructure. Results show that basic physical properties of modified Portland cement with Ba-bearing sulphoaluminate minerals (SMPC are similar with PC except the shorter setting time. Ettringite and C-S-H are the main hydrating produces in SMPC, which is similar to Portland cement (PC. Because of volume expansion of ettringite, SMPC paste structure is denser than PC according to SEM-EDS analysis and the pore size and pore content of SMPC pastes was smaller especially for the harmful pores. Because sulfur aluminum barium calcium was a new early-strength mineral and parts of BaO went into the C₂S lattice and caused lattice distortion to enhance C₂S hydration activity, the compressive strengths of SMPC grew faster and higher than PC.

  20. Comparative Analysis of Selected Physicochemical Properties of Pozzolan Portland and MTA-Based Cements.

    Science.gov (United States)

    Dorileo, Maura Cristiane Gonçales Orçati; Villa, Ricardo Dalla; Guedes, Orlando Aguirre; Aranha, Andreza Maria Fábio; Semenoff-Segundo, Alex; Bandeca, Matheus Coelho; Borges, Alvaro Henrique

    2014-01-01

    Physicochemical properties of pozzolan Portland cement were compared to ProRoot MTA and MTA BIO. To test the pH, the samples were immersed in distilled water for different periods of time. After the pH analysis, the sample was retained in the plastic recipient, and the electrical conductivity of the solution was measured. The solubility and radiopacity properties were evaluated according to specification 57 of the American National Standard Institute/American Dental Association (ANSI/ADA). The statistical analyses were performed using ANOVA and Tukey's test at a 5% level of significance. Pozzolan Portland cement exhibited pH and electrical conductivity mean values similar to those of the MTA-based cements. The solubilities of all tested materials were in accordance with the ANSI/ADA standards. Only the MTA-based cements met the ANSI/ADA recommendations for radiopacity. It might be concluded that the pH and electrical conductivity of pozzolan Portland cement are similar to and comparable to those of MTA-based cements.

  1. Comparative SEM study of the marginal adaptation of white and grey MTA and Portland cement.

    Science.gov (United States)

    Bidar, Maryam; Moradi, Saeed; Jafarzadeh, Hamid; Bidad, Salma

    2007-04-01

    The use of a suitable substance that prevents egress of potential contaminants into the periapical tissues is important in endodontic surgery. The aim of the present study was to compare the marginal adaptation of three root-end filling materials (white mineral trioxide aggregate (MTA), grey MTA and Portland cement), using scanning electron microscopy. Seventy-five single-rooted extracted human teeth were used. The canals were instrumented and filled with gutta-percha. Following root-end resection and cavity preparation, root-end cavities were filled with white MTA, grey MTA or Portland cement. Using a diamond saw, roots were longitudinally sectioned into two halves. Under scanning electron microscopy, the gaps between the material and dentinal wall were measured. The data were analysed using Kruskal-Wallis test. The mean of the gap in grey MTA, white MTA and Portland cement was 211.6, 349 and 326.3 microm, respectively. The results indicate that the gap between grey MTA and the dentinal wall is less than other materials, but there was no significant difference between the materials tested in this study (P > 0.05).

  2. Model Analysis of Initial Hydration and Structure Forming of Portland Cement

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The auto efficiently hydration heat arrangement and the non-contacting electrical resistivity device were used to test the thermology effect and the resistivity variation of Portland cement hydration.The structure forming model of Portland cement initial hydration was established through the systematical experiments with different cements, the amount of mixing water and the chemical admixture. The experimental results show that, the structure forming model of cement could be divided into three stages, i e, solution-solution equilibrium period, structure forming period and structure stabilizing period. Along with the increase of mixing water, the time of inflexion appeared is in advance for thermal process of cement hydration and worsened for the structure forming process. Comparison with the control specimen, adding Na2SO4 makes the minimum critical point lower, the flattening period shorter and the growing slope after stage one steeper. So the hydration and structure forming process of Portland cement could be described more exactly by applying the thermal model and the structure-forming model.

  3. Rheological Properties of Very High-Strength Portland Cement Pastes: Influence of Very Effective Superplasticizers

    Directory of Open Access Journals (Sweden)

    Adriano Papo

    2010-01-01

    Full Text Available The influence of the addition of very effective superplasticizers, that are commercially available, employed for maximising the solid loading of very high-strength Portland cement pastes, has been investigated. Cement pastes were prepared from deionized water and a commercially manufactured Portland cement (Ultracem 52.5 R. Cement and water were mixed with a vane stirrer according to ASTM Standard C305. The 0.38 to 0.44 water/cement ratio range was investigated. Three commercial superplasticizing agents produced by Ruredil S.p.a. were used. They are based on a melamine resin (Fluiment 33 M, on a modified lignosulphonate (Concretan 200 L, and on a modified polyacrylate (Ergomix 1000. Rheological tests were performed at 25°C by using the rate controlled coaxial cylinder viscometer Rotovisko-Haake 20, system M5-osc., measuring device MV2P with serrated surfaces. The tests were carried out under continuous flow conditions. The results of this study were compared with those obtained in a previous article for an ordinary Portland cement paste.

  4. Effects of oral environment stabilization procedures on counts of Candida spp. in children Efeitos da adequação do meio bucal na contagem de Candida spp. em crianças

    Directory of Open Access Journals (Sweden)

    Marcos Augusto do Rego

    2003-12-01

    microorganismos em crianças. Foram coletados enxágües bucais de 30 meninos e 30 meninas com idades entre quatro e dez anos, positivos para Candida na saliva, obtendo-se a contagem inicial. As crianças foram divididas ao acaso em dois grupos e procedeu-se à adequação de meio utilizando um dos cimentos a serem testados. Uma semana depois, novo enxágüe bucal foi coletado, obtendo-se, dessa forma, a contagem final de Candida spp. Uma redução expressiva nas contagens foi observada em ambos os grupos. Os dois materiais testados foram eficazes na diminuição das contagens de Candida, e diferenças estatisticamente significantes foram observadas entre as contagens inicial e final nos dois grupos. Considerando o percentual de redução, o cimento de óxido de zinco e eugenol apresentou resultados mais favoráveis, promovendo uma redução de 70%, ao passo que para o cimento de ionômero de vidro esse valor foi de 46%. De acordo com os resultados obtidos, concluiu-se que a adequação de meio é um procedimento eficaz na redução das contagens de Candida spp. na cavidade bucal, especialmente quando o cimento de óxido de zinco e eugenol é utilizado.

  5. Influência do alívio, tipo de cimento e anatomia radicular na remoção de núcleos metálicos com ultrassom sob diferentes condições

    OpenAIRE

    2009-01-01

    O objetivo deste estudo foi avaliar o tempo de remoção de núcleos metálicos utilizando o ultrassom, dentro das variáveis: confecção de alívio, tipo de cimento (fosfato de zinco e ionômero de vidro) e anatomia do conduto radicular (circular e oval). Para isto, foram selecionados 80 dentes humanos higidos unirradiculares (caninos superiores e inferiores, incisivos superiores e pré molares inferiores) com diâmetros radiculares. Os dentes tiveram as coroas removidas e os canais radiculares recebe...

  6. Obtenção e caracterização de espumas de cimento de fosfato de cálcio: avaliação dos métodos de emulsão e gelcasting Fabrication and characterization of calcium phosphate cement foams: evaluation of emulsion and gelcasting methods

    Directory of Open Access Journals (Sweden)

    E. de Sousa

    2012-12-01

    Full Text Available Em Engenharia Tecidual, a fabricação de scaffolds capazes de guiar o crescimento, a organização e a diferenciação de células no processo de formação de novos tecidos apresenta grande relevância. Várias são as técnicas de processamento para a fabricação desta classe de material: réplica de esponjas poliméricas, incorporação de material orgânico ao pó cerâmico, gelcasting, emulsão, entre outras. Na fabricação de scaffolds focados na terapia de tecidos ósseos, os cimentos de fosfato de cálcio (CFC apresentam grande destaque, pois além de reabsorvíveis, apresentam morfologia e composição química semelhante à fase mineral óssea. Este trabalho tem como objetivo a obtenção de espumas de CFC por meio de duas rotas de processamento, emulsão e gelcasting. As espumas foram caracterizadas quanto suas propriedades físicas e mecânicas e as fases cristalinas formadas após a cura do cimento foram determinadas por difração de raios X. As amostras obtidas por ambos os métodos apresentaram porosidade entre 58-62% e microestrutura constituída de poros aproximadamente esféricos (d50=50-100 µm. A resistência mecânica das amostras variou entre 5,5-1,5 MPa. As fases cristalinas encontradas foram monetita (CaHPO4 e brushita (CaHPO4 2H2O.In Tissue Engineering, the need for scaffolds which are capable of guiding the organization, differentiation and growth of cells leading to the formation of new tissues is highly relevant. For the development of new scaffolds focused on bone tissue therapy, calcium phosphate cements (CPC have great potential, because besides their resorbability, they present morphology and chemical composition similar to the bone mineral phase. Moreover, there are several processing techniques to produce ceramic scaffolds: polymeric sponge replication, incorporation of organic material into the ceramic powder, gelcasting, emulsion, among others. The aim of this work was to obtain CPCs foams by using two

  7. Influência de materiais restauradores liberadores de flúor na evolução de lesões de cárie em esmalte de molares decíduos

    OpenAIRE

    Santos,Lucineide de Melo

    2001-01-01

    Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde, Curso de Pós-Graduação em Odontologia. O objetivo deste estudo foi avaliar a influência de materiais restauradores liberadores de flúor na evolução de lesões de cárie em esmalte, quando aplicados em molares decíduos e submetidos a uma situação de alto desafio cariogênico. Os resultados sugerem que os cimentos de ionômero de vidro oferecem maior resistência à lesão de cárie secundária que a resina compos...

  8. Reaction of rat subcutaneous tissue to mineral trioxide aggregate and Portland cement: A secondary level biocompatibility test

    Directory of Open Access Journals (Sweden)

    P Karanth

    2013-01-01

    Full Text Available Objectives: This secondary-level animal study was conducted to assess and compare the subcutaneous tissue reaction to implantation of white mineral trioxide aggregate (MTA and white Portland cement. Study Design: Polyethylene tubes filled with either freshly mixed white MTA (Group I or white Portland cement (Group II were implanted subcutaneously into 12 Wistar Albino rats. Each animal also received an empty polyethylene tube as the control (Group III. After 7, 14, 21 and 30 days, the implants, together with surrounding tissues were excised. Two pathologists blinded to the experimental procedure, evaluated sections taken from the biopsy specimens for the severity of the inflammatory response, calcification and the presence and thickness of fibrous capsule surrounding the implant. Statistical analysis was performed using the Cross-tabs procedure, Univariate analysis of the variance two-way and the Pearson product moment correlation to assess inter-rater variability between the two evaluators. Results: At 7 days, there was no significant difference in the severity of inflammation between the control group, white MTA, and white Portland cement groups. In the 14 day, 21 day and 30 day test periods, control group had significantly less inflammation than white MTA and white Portland cement. There was no significant difference in the grading of inflammation between white MTA and white Portland cement. All materials exhibited thick capsule at 7 days and thin capsule by 30 days. Conclusion: Both white MTA and white Portland cement were not completely non-irritating at the end of 30 days as evidenced by the presence of mild inflammation. However, the presence of a thin capsule around the materials, similar to the control group, indicates good tissue tolerance. White MTA and white Portland cement seem to be materials of comparable biocompatibility.

  9. O entendimento do espaço em Ângelo de Sousa a dança‑minimalista e a experiência do observador‑experimentador

    OpenAIRE

    Rosas, Patrícia

    2012-01-01

    Ângelo de Sousa (1938-2011) mereceu a denominação de “experimentador”, e é sob a lente da “experimentação” que olhámos para o seu percurso, e mais especificamente para o filme experimental Chão de Cimento (1) (1972), em Super 8, com cerca de 4’43’’ (cor e sem som). Este ensaio é marcado por dois objectivos principais. Em primeiro lugar, procura perceber o que é a experimentação no trabalho de Ângelo de Sousa, partindo da definição de experimentação de José Gil, e entender qual a relação de...

  10. Avaliação da microinfiltração marginal e profundidade de penetração dos cimentos de ionômero de vidro utilizados como selantes oclusais Evaluation of marginal microleakage and depth of penetration of glass ionomer cements used as occlusal sealants

    Directory of Open Access Journals (Sweden)

    Marina de Lourdes Calvo Fracasso

    2005-09-01

    Full Text Available OBJETIVE: the aim of this study was to conduct an in vitro comparison of marginal microleakage (MM and the depth of penetration (DP of glass ionomer cements (GIC and a resin sealant (RS into occlusal pit and fissures. METHODS: for that purpose, 60 intact third molars were equally distributed to 5 groups: G1 - 37% phosphoric acid / Delton; G2 - 40% polyacrylic acid / Ketac-Molar / nail varnish; G3 - Fuji Plus conditioner / Fuji Plus/ nail varnish; G4 -37% phosphoric acid / Vitremer / Finishing gloss; G5 -37% phosphoric acid / Vitremer prepared with a 1:4 ratio of powder / Finishing gloss. The teeth were submitted to a thermal treatment corresponding to 300 cycles (15 sec, 5/55(0C, followed by complete coating with nail varnish, except for 1mm beyond the contour of the sealant. Afterwards, the teeth were immersed in 0.5% basic fuchsine for 24 hours. Thereafter, the teeth were sectioned in buccolingual direction and microscopically analyzed (150x magnification by means of predetermined scores. The results were subject to the Kruskal-Wallis test. RESULTS: there was no statistical difference between the materials tested in relation to the DP, being that all groups displayed nearly complete filling of the fissures. No sealant material was able to prevent dye penetration; however, the GICs provided better results of MM, with significant difference when compared to the RS. CONCLUSION: all materials investigated presented a satisfactory degree of penetration into the fissures; however, the glass ionomer cements displayed better performance in the marginal microleakage test compared to the resin sealant.OBJETIVO: o objetivo deste estudo foi comparar in vitro a microinfiltração marginal (MM e o grau de profundidade de penetração (DP de cimentos de ionômero de vidro (CIV e um selante resinoso (SR em fossas e fissuras oclusais. MATERIAIS E MÉTODOS: para tanto, 60 terceiros molares hígidos foram igualmente distribuídos em 5 grupos: G1- ácido fosf

  11. Biocompatibility assessment of modified Portland cement in comparison with MTA® : In vivo and in vitro studies

    Directory of Open Access Journals (Sweden)

    I Khalil

    2012-01-01

    Full Text Available Aim: The aim of our study is to elaborate a new cement based on Portland cement (PC, Modified Portland Cement (MPC with modified chemical and physical properties that allow easier clinical manipulation and faster setting time than MTA® and then to evaluate its cytotoxicity in vitro and its biocompatibility in vivo in comparison with MTA® . Materials and Methods: Elaboration of MPC: Portland cement powder slenderly grinded to homogenize the particles, mixed with a radiopaque element and a setting time accelerator. A comparative in vitro study (MTS test of the toxic effect of MTA® and MPC with culture isolated from the calvaria of 18-day-old fetal Swiss OF1 mice are done. A comparative in vivo study of the biocompatibility of MTA® and MPC: Under general anaesthesia, three holes (2.5 mm were made in both the left and right femurs of six White New Zealand rabbits. In the first hole MPC is placed, in the second MTA® and the third one is left empty (negative control group. Three weeks after implantation, two rabbits are sacrificed, then two other rabbits over six weeks and the last two after twelve weeks. The neck of the femur is trimmed and prepared for undecalcified histological studies. Mann-Whitney test was used to analyze the results. Results: The cell viability test according to the morphological observations suggested the biocompatibility of the two biomaterials tested. The in vivo test showed similar biocompatibility between MTA® and MPC. Bone healing and minimal inflammatory response adjacent to MTA® and MPC implants were observed at all experimental periods (3, 6 and 12 weeks, suggesting that both materials are well tolerated. Conclusion: This pilot comparative study of MTA® and MPC showed no or very limited toxic effects of both cements in vitro and similar biocompatibility in vivo. However, additional in vivo and clinical studies should be done on MPC before it can be introduced in our clinical practice.

  12. Hydration study of ordinary portland cement in the presence of zinc ions

    Directory of Open Access Journals (Sweden)

    Monica Adriana Trezza

    2007-12-01

    Full Text Available Hydration products of Portland cement pastes, hydrated in water and in the presence of zinc ions were studied comparatively at different ages. Hydration products were studied by X ray diffractions (XRD and infrared spectroscopy (IR. Although IR is not frequently used in cement chemistry, it evidenced a new phase Ca(Zn(OH32. 2H2O formed during cement hydration in the presence of zinc. The significant retardation of early cement hydration in the presence of zinc is assessed in detail by differential calorimetry as a complement to the study carried out by IR and XRD, providing evidence that permits to evaluate the kinetic of the early hydration.

  13. Evolution and quantification of the main sensitisers in commercial Portland cements

    OpenAIRE

    2002-01-01

    [ES] Los cementos Portland comerciales contienen elementos minoritarios en su composición química. La presencia de estos elementos tiene una incidencia directa en diferentes aspectos: comportamiento reológico, cinética de reacción, contaminación ambiental, etc. Algunos de ellos, aparte de su incidencia mencionada anteriormente, tienen un efecto negativo en la salud humana. Así, el cromo (Cr), níquel (Ni) y cobalto (Co) son los principales alérgenos contenidos en los cementos y, po...

  14. Tritium/Helium-3 Apparent Ages of Shallow Ground Water, Portland Basin, Oregon, 1997-98

    Science.gov (United States)

    Hinkle, Stephen R.

    2009-01-01

    Water samples for tritium/helium-3 age dating were collected from 12 shallow monitoring wells in the Portland basin, Oregon, in 1997, and again in 1998. Robust tritium/helium-3 apparent (piston-flow) ages were obtained for water samples from 10 of the 12 wells; apparent ages ranged from 1.1 to 21.2 years. Method precision was demonstrated by close agreement between data collected in 1997 and 1998. Tritium/helium-3 apparent ages generally increase with increasing depth below the water table, and agree well with age/depth relations based on assumptions of effects of recharge rate on vertical ground-water movement.

  15. Hydration of portland cement, natural zeolite mortar in water and sulphate solution

    Directory of Open Access Journals (Sweden)

    Janotka, I.

    2003-03-01

    Full Text Available The objective of this paper is to characterise sulphate resistance of mortars made from ordinary Portland cement ( PC and Portland-pozzolan cement with 35 wt.% of zeolite addition (zeolite-blended cement-ZBC . Mortars with two different cement types were tested in water and 5% sodium sulphate solution for 720 days. A favourable effect of zeolite on increased sulphate resistance of the cement is caused by decrease in free Ca(OH2 content of the mortar There is not sufficient of Ca(OH2 available for reacting with the sulphate solution to form voluminous reaction products. A decreased C3A, content due to 35 wt.% replacement of PC by zeolite is the next pronounced factor improving resistance of the mortar with such blended cement.

    El objetivo de este trabajo ha sido estudiar la resistencia a los sulfatos de morteros preparados con cemento portland ordinario (PC y cemento portland puzolánico, con un 35% en peso de zeolita (zeolite-blended cement (ZBC. Ambos tipos de morteros fueron conservados en agua y en una disolución de sulfato sódico al 5% durante 720 días. Se observó una mayor resistencia a los sulfatos en el mortero preparado con el cemento que contenía zeolita debido a su menor contenido en Ca(OH2. No hay cantidad suficiente de Ca(OH2 para que se produzca la reacción de los constituyentes de la pasta con la disolución de sulfato sódico y formar así productos de naturaleza expansiva. La disminución en el contenido de C,3A, debida a la sustitución de un 35% en peso de PC por zeolita, es el factor más determinante en el aumento de la resistencia del mortero en los cementos con adición.

  16. Conduction calorimetric studies of ternary binders based on Portland cement, calcium aluminate cement and calcium sulphate

    OpenAIRE

    Torrens Martín, David; Fernández Carrasco, Lucía; Blanco Varela, M.Teresa

    2013-01-01

    Different binders of Portland cement, calcium aluminate cement and calcium sulphate (PC/CAC/CS) have been investigated to determinate the in¿uence the CAC and CS amount in the reactions mechanism. Several mixtures were studied, ratios of 100, 85/15 and 75/25 of PC/CAC with 0, 3 and 5 % of CS. Conduction calorimetric technique was used to follow the hydration during 100 h. The XRD and FTIR techniques were used as support in the analysis of the hydration products. The results have shown tha...

  17. Dimensional stability of materials based on Portland cement at the early stages

    Science.gov (United States)

    Mesa Yandy, Angélica; Zerbino, Raúl L.; Giaccio, Graciela M.; Russo, Nélida A.; Duchowicz, Ricardo

    2014-09-01

    In this work two fiber optic sensing techniques are used to study the dimensional stability in fresh state of different cementitious materials. A conventional Portland cement mortar and two commercial grouts were selected. The measurements were performed by using a Bragg grating embedded in the material and a non-contact Fizeau interferometer. The first technique was applied in a horizontal sample scheme, and the second one, by using a vertical configuration. In addition, a mechanical length comparator was used in the first case in order to compare the results. The evolution with time of the dimensional changes of the samples and the analysis of the observed behavior are included.

  18. A Comparative Study Between the Early Stages Hydration of a High Strength and Sulphate Resistant Portland Cement and the Type II F Portland Cement Through Non Conventional Differential Thermal Analysis and Thermogravimetry

    OpenAIRE

    Neves Junior,Alex; Viana,Marcelo Mendes; Dweck,Jo; Toledo Filho,Romildo Dias

    2015-01-01

    This work presents a study, which compares the early stages of hydration of a High Initial Strength and Sulphate Resistant Portland Cement (HIS SR PC) with those of Type II F Portland Cement (PC II), by Non-Conventional Differential Thermal Analysis (NCDTA) within the first 24 hours of hydration. Water/cement (w/c) ratios equal to 0.5, 0.6 and 0.66 were used to prepare the pastes. The hydration of these two types of cement was monitored on real time by NCDTA curves, through the thermal effect...

  19. Improved quantification of alite and belite in anhydrous Portland cements by 29Si MAS NMR: Effects of paramagnetic ions

    DEFF Research Database (Denmark)

    Poulsen, Søren Lundsted; Kocaba, Vanessa; Le Saoût, Gwenn;

    2009-01-01

    The applicability, reliability, and repeatability of 29Si MAS NMR for determination of the quantities of alite (Ca3SiO5) and belite (Ca2SiO4) in anhydrous Portland cement was investigated in detail for 11 commercial Portland cements and the results compared with phase quantifications based...... on powder X-ray diffraction combined with Rietveld analysis and with Taylor-Bogue calculations. The effects from paramagnetic ions (Fe3+) on the spinning sideband intensities, originating from dipolar couplings between 29Si and the spins of the paramagnetic electrons, were considered and analyzed in spectra...

  20. Microstructure Development and Transport Properties of Portland Cement-fly Ash Binary Systems: in view of service life predictions

    OpenAIRE

    Z. Yu

    2015-01-01

    Fly ash is a by-product of burning coal in electric power generating plants. It is commonly known that owing to its pozzolanic properties fly ash is widely used as a partial replacement for Portland cement in concrete. The use of fly ash in concrete not only reduces the landfill costs of fly ash, but also reduces the use of Portland cement in concrete, consequently reduces CO2 emission per ton concrete. More important, the presence of fly ash improves the durability of concrete and extends th...

  1. Food mirages: geographic and economic barriers to healthful food access in Portland, Oregon.

    Science.gov (United States)

    Breyer, Betsy; Voss-Andreae, Adriana

    2013-11-01

    This paper investigated the role of grocery store prices in structuring food access for low-income households in Portland, Oregon. We conducted a detailed healthful foods market basket survey and developed an index of store cost based on the USDA Thrifty Food Plan. Using this index, we estimated the difference in street-network distance between the nearest low-cost grocery store and the nearest grocery store irrespective of cost. Spatial regression of this metric in relation to income, poverty, and gentrification at the census tract scale lead to a new theory regarding food access in the urban landscape. Food deserts are sparse in Portland, but food mirages are abundant, particularly in gentrifying areas where poverty remains high. In a food mirage, grocery stores are plentiful but prices are beyond the means of low-income households, making them functionally equivalent to food deserts in that a long journey to obtain affordable, nutritious food is required in either case. Results suggested that evaluation of food environments should, at a minimum, consider both proximity and price in assessing healthy food access for low-income households.

  2. Full phase analysis of portland clinker by penetrating synchrotron powder diffraction.

    Science.gov (United States)

    de la Torre, A G; Cabeza, A; Calvente, A; Bruque, S; Aranda, M A

    2001-01-15

    Fabrication of portland cements commonly depends on X-ray fluorescence (XRF), which measures the elemental compositions. XRF is used to adjust the raw material proportions and to control the process conditions. However, to predict the mechanical strength of the resulting concrete, it is essential to know the phase composition which is, so far, indirectly inferred by the Bogue method. Here, we report a phase analysis of an industrial portland clinker containing six crystalline phases, Ca3SiO5, Ca2SiO4, Ca4Al2Fe2O10, Ca3Al2O6, NaK3(SO4)2, and CaO, by Rietveld refinement of synchrotron X-ray powder diffraction data (lambda = 0.442377 A). Even the minor component, CaO 0.45(2)%, was readily analyzed. We have also carried out a phase study of the same clinker with laboratory X-rays to characterize the changes in the detection limit and errors. Furthermore, by adding a suitable crystalline standard to the same clinker, we have determined the overall amorphous phase content. The procedure established for this state-of-the-art phase analysis shows the high precision that can be achieved by using penetrating X-rays, which is of interest not only in cement chemistry but in other industrially important multiphase systems such as slags, superalloys, or catalysts.

  3. Recycling of porcelain tile polishing residue in portland cement: hydration efficiency.

    Science.gov (United States)

    Pelisser, Fernando; Steiner, Luiz Renato; Bernardin, Adriano Michael

    2012-02-21

    Ceramic tiles are widely used by the construction industry, and the manufacturing process of ceramic tiles generates as a major residue mud derived from the polishing step. This residue is too impure to be reused in the ceramic process and is usually discarded as waste in landfills. But the analysis of the particle size and concentration of silica of this residue shows a potential use in the manufacture of building materials based on portland cement. Tests were conducted on cement pastes and mortars using the addition of 10% and 20% (mass) of the residue. The results of compressive strength in mortars made up to 56 days showed a significant increase in compressive strength greater than 50%. The result of thermogravimetry shows that portlandite is consumed by the cement formed by the silica present in the residue in order to form calcium silicate hydrate and featuring a pozzolanic reaction. This effect improves the performance of cement, contributes to research and application of supplementary cementitious materials, and optimizes the use of portland cement, reducing the environmental impacts of carbon dioxide emissions from its production.

  4. The Greenhouse Gas Emission from Portland Cement Concrete Pavement Construction in China.

    Science.gov (United States)

    Ma, Feng; Sha, Aimin; Yang, Panpan; Huang, Yue

    2016-06-24

    This study proposes an inventory analysis method to evaluate the greenhouse gas (GHG) emissions from Portland cement concrete pavement construction, based on a case project in the west of China. The concrete pavement construction process was divided into three phases, namely raw material production, concrete manufacture and pavement onsite construction. The GHG emissions of the three phases are analyzed by a life cycle inventory method. The CO₂e is used to indicate the GHG emissions. The results show that for 1 km Portland cement concrete pavement construction, the total CO₂e is 8215.31 tons. Based on the evaluation results, the CO₂e of the raw material production phase is 7617.27 tons, accounting for 92.7% of the total GHG emissions; the CO₂e of the concrete manufacture phase is 598,033.10 kg, accounting for 7.2% of the total GHG emissions. Lastly, the CO₂e of the pavement onsite construction phase is 8396.59 kg, accounting for only 0.1% of the total GHG emissions. The main greenhouse gas is CO₂ in each phase, which accounts for more than 98% of total emissions. N₂O and CH₄ emissions are relatively insignificant.

  5. The impact of zirconium oxide radiopacifier on the early hydration behaviour of white Portland cement.

    Science.gov (United States)

    Coleman, Nichola J; Li, Qiu

    2013-01-01

    Zirconium oxide has been identified as a candidate radiopacifying agent for use in Portland cement-based biomaterials. During this study, the impact of 20 wt.% zirconium oxide on the hydration and setting reactions of white Portland cement (WPC) was monitored by powder X-ray diffraction (XRD), (29)Si and (27)Al magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR), transmission electron microscopy (TEM) and Vicat apparatus. The presence of 20 wt.% zirconium oxide particles in the size-range of 0.2 to 5 μm was found to reduce the initial and final setting times of WPC from 172 to 147 min and 213 to 191 min, respectively. Zirconium oxide did not formally participate in the chemical reactions of the hydrating cement; however, the surface of the zirconium oxide particles presented heterogeneous nucleation sites for the precipitation and growth of the early C-S-H gel products which accelerated the initial setting reactions. The presence of zirconium oxide was found to have little impact on the development of the calcium (sulpho)aluminate hydrate phases.

  6. Use of ancient copper slags in Portland cement and alkali activated cement matrices.

    Science.gov (United States)

    Nazer, Amin; Payá, Jordi; Borrachero, María Victoria; Monzó, José

    2016-02-01

    Some Chilean copper slag dumps from the nineteenth century still remain, without a proposed use that encourages recycling and reduces environmental impact. In this paper, the copper slag abandoned in landfills is proposed as a new building material. The slags studied were taken from Playa Negra and Púquios dumps, both located in the region of Atacama in northern Chile. Pozzolanic activity in lime and Portland cement systems, as well as the alkali activation in pastes with copper slag cured at different temperatures, was studied. The reactivity of the slag was measured using thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), electrical conductivity and pH in aqueous suspension and Fourier Transform Infrared Spectroscopy (FTIR). Furthermore, copper slag-Portland cement mortars with the substitution of 25% (by weight) of cement by copper slag and alkali-activated slag mortars cured at 20 and 65 °C were made, to determine the compressive strength. The results indicate that the ancient copper slags studied have interesting binding properties for the construction sector.

  7. Properties of expansive cements, made with Portland cement, gypsum and high alumina cement

    Directory of Open Access Journals (Sweden)

    Monfore, G. E.

    1966-03-01

    Full Text Available Not availableLos cementos expansivos se han desarrollado durante las tres décadas pasadas, principalmente por las investigaciones llevadas a cabo en Francia, URSS y Estados Unidos. Los cementos expansivos que fueron utilizados en los estudios de los cuales se da cuenta en el presente trabajo se obtuvieron mediante la mezcla de cemento Portland, cemento aluminoso y yeso. En las investigaciones se utilizaron morteros con los cuales se pudo determinar los efectos de la composición, tiempo y temperatura de curado sobre las resistencias, dilatación libre, retracción y desarrollo de resistencias en probetas pretensadas. Se hace una revisión sobre los estudios hechos con cementos expansivos y desarrollados en la Universidad de California. Las propiedades de taIes hormigones son, en términos generales, comparables a aquellos obtenidos con mezclas de cementos portland, cemento aluminoso y yeso. Es necesaria más información sobre pérdidas de tensión en los aceros y durabilidad de los hormigones autopretensados.

  8. Application of the fluorescence light microscopy in the textural study of portland cement clinker

    Directory of Open Access Journals (Sweden)

    Montoto San Miguel, Modesto

    1987-03-01

    Full Text Available The application of fluorescence light microscopy in the textural study of Portland cement clinker, specially its porosity, is presented. Principles and types of the technique are commented and the suggested sample preparation method is described. The use of fluorescence microscopy allows an easier study of the clinker porosity, and very proper images for automated quantification can be obtained. Besides, the samples can also be observed by reflected-light polarizing microscopy.

    Se presenta la utilidad de la microscopía óptica de fluorescencia para el estudio textural del clínker de cemento Portland, especialmente su porosidad. Se comentan los fundamentos y modalidades de la técnica, y se describe el método recomendado de preparación de muestras. La utilización de la microscopía de fluorescencia permite un estudio más fácil de la porosidad, obteniéndose imágenes muy apropiadas para su cuantificación mediante técnicas automatizadas. Además, las muestras para fluorescencia pueden ser estudiadas complementariamente por microscopía óptica de polarización por luz reflejada.

  9. Bioactive coatings on Portland cement substrates: Surface precipitation of apatite-like crystals

    Energy Technology Data Exchange (ETDEWEB)

    Gallego, Daniel [Biomedical Engineering Department, Ohio State University, 1080 Carmack Road, 270 Bevis Hall, Columbus (OH) - 43210 (United States); Higuita, Natalia [Biomedical Engineering Department, Ohio State University, 1080 Carmack Road, 270 Bevis Hall, Columbus (OH) - 43210 (United States); Grupo de Investigacion en Ingenieria Biomedica CES-EIA (GIBEC), Carrera 43 A No. 52 Sur - 99, Sabaneta (Colombia); Garcia, Felipe [Grupo de Investigacion en Ingenieria Biomedica CES-EIA (GIBEC), Carrera 43 A No. 52 Sur - 99, Sabaneta (Colombia); Ferrell, Nicholas [Biomedical Engineering Department, Ohio State University, 1080 Carmack Road, 270 Bevis Hall, Columbus (OH) - 43210 (United States); Hansford, Derek J. [Biomedical Engineering Department, Ohio State University, 1080 Carmack Road, 270 Bevis Hall, Columbus (OH) - 43210 (United States)], E-mail: hansford.4@osu.edu

    2008-04-01

    We report a method for depositing bioactive coatings onto cement materials for bone tissue engineering applications. White Portland cement substrates were hydrated under a 20% CO{sub 2} atmosphere, allowing the formation of CaCO{sub 3}. The substrates were incubated in a calcium phosphate solution for 1, 3, and 6 days (CPI, CPII, and CPIII respectively) at 37 deg. C to induce the formation of carbonated apatite. Cement controls were prepared and hydrated with and without CO{sub 2} atmosphere (C+ and C- respectively). The presence of apatite-like crystals was verified by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). The substrate cytocompatibility was evaluated via SEM after 24 hour cell cultures. SEM revealed the presence Ca(OH){sub 2} on C-, and CaCO{sub 3} on C+. Apatite-like crystals were detected only on CPIII, confirmed by phosphorus EDS peaks only for CPIII. Cells attached and proliferated similarly well on all the substrates except C-. These results prove the feasibility of obtaining biocompatible and bioactive coatings on Portland cement for bone tissue engineering applications.

  10. Use of disposed waste ash from landfills to replace Portland cement.

    Science.gov (United States)

    Rukzon, Sumrerng; Chindaprasirt, Prinya

    2009-09-01

    In this study, waste ash was utilized as a pozzolanic material in blended Portland cement in order to reduce negative environmental effects and landfill volume required to dispose of waste ash. The influence of waste ash, namely palm oil fuel ash, rice husk ash and fly ash on compressive strength and sulfate resistance in mortar were studied and evaluated by some accelerated short-term techniques in sodium sulfate solutions. Ordinary Portland cement (OPC) was partially replaced with ground palm oil fuel ash (POA), ground rice husk ash (RHA) and classified fly ash (FA). Single pozzolan and a blend of equal weight portions of POA, RHA and FA were also used. The resistance to sulfate attack of mortar improves substantially with partial replacement of OPC with POA, RHA and FA. The use of a blend of equal weight portions of FA and POA or RHA produced mixes with good strength and resistance to sulfate attack. POA, RHA and FA have a high potential to be used as a pozzolanic material.

  11. A Thermoelectric Waste-Heat-Recovery System for Portland Cement Rotary Kilns

    Science.gov (United States)

    Luo, Qi; Li, Peng; Cai, Lanlan; Zhou, Pingwang; Tang, Di; Zhai, Pengcheng; Zhang, Qingjie

    2015-06-01

    Portland cement is produced by one of the most energy-intensive industrial processes. Energy consumption in the manufacture of Portland cement is approximately 110-120 kWh ton-1. The cement rotary kiln is the crucial equipment used for cement production. Approximately 10-15% of the energy consumed in production of the cement clinker is directly dissipated into the atmosphere through the external surface of the rotary kiln. Innovative technology for energy conservation is urgently needed by the cement industry. In this paper we propose a novel thermoelectric waste-heat-recovery system to reduce heat losses from cement rotary kilns. This system is configured as an array of thermoelectric generation units arranged longitudinally on a secondary shell coaxial with the rotary kiln. A mathematical model was developed for estimation of the performance of waste heat recovery. Discussions mainly focus on electricity generation and energy saving, taking a Φ4.8 × 72 m cement rotary kiln as an example. Results show that the Bi2Te3-PbTe hybrid thermoelectric waste-heat-recovery system can generate approximately 211 kW electrical power while saving 3283 kW energy. Compared with the kiln without the thermoelectric recovery system, the kiln with the system can recover more than 32.85% of the energy that used to be lost as waste heat through the kiln surface.

  12. Effect of blastfurnace slag addition to Portland cement for cationic exchange resins encapsulation

    Directory of Open Access Journals (Sweden)

    Stefan L.

    2013-07-01

    Full Text Available In the nuclear industry, cement-based materials are extensively used to encapsulate spent ion exchange resins (IERs before their final disposal in a repository. It is well known that the cement has to be carefully selected to prevent any deleterious expansion of the solidified waste form, but the reasons for this possible expansion are not clearly established. This work aims at filling the gap. The swelling pressure of IERs is first investigated as a function of ions exchange and ionic strength. It is shown that pressures of a few tenths of MPa can be produced by decreases in the ionic strength of the bulk solution, or by ion exchanges (2Na+ instead of Ca2+, Na+ instead of K+. Then, the chemical evolution of cationic resins initially in the Na+ form is characterized in CEM I (Portland cement and CEM III (Portland cement + blastfurnace slag cements at early age and an explanation is proposed for the better stability of CEM III material.

  13. The Estimation of Compaction Parameter Values Based on Soil Properties Values Stabilized with Portland Cement

    Science.gov (United States)

    Lubis, A. S.; Muis, Z. A.; Pasaribu, M. I.

    2017-03-01

    The strength and durability of pavement construction is highly dependent on the properties and subgrade bearing capacity. This then led to the idea of the selection methods to estimate the density of the soil with the proper implementation of the system, fast and economical. This study aims to estimate the compaction parameter value namely the maximum dry unit weight (γd max) and optimum moisture content (wopt) of the soil properties value that stabilized with Portland Cement. Tests conducted in the laboratory of soil mechanics to determine the index properties (fines and liquid limit) and Standard Compaction Test. Soil samples that have Plasticity Index (PI) between 0-15% then mixed with Portland Cement (PC) with variations of 2%, 4%, 6%, 8% and 10%, each 10 samples. The results showed that the maximum dry unit weight (γd max) and wopt has a significant relationship with percent fines, liquid limit and the percentation of cement. Equation for the estimated maximum dry unit weight (γd max) = 1.782 - 0.011*LL + 0,000*F + 0.006*PS with R2 = 0.915 and the estimated optimum moisture content (wopt) = 3.441 + 0.594*LL + 0,025*F + 0,024*PS with R2 = 0.726.

  14. DSC and TG Analysis of a Blended Binder Based on Waste Ceramic Powder and Portland Cement

    Science.gov (United States)

    Pavlík, Zbyšek; Trník, Anton; Kulovaná, Tereza; Scheinherrová, Lenka; Rahhal, Viviana; Irassar, Edgardo; Černý, Robert

    2016-03-01

    Cement industry belongs to the business sectors characteristic by high energy consumption and high {CO}2 generation. Therefore, any replacement of cement in concrete by waste materials can lead to immediate environmental benefits. In this paper, a possible use of waste ceramic powder in blended binders is studied. At first, the chemical composition of Portland cement and ceramic powder is analyzed using the X-ray fluorescence method. Then, thermal and mechanical characterization of hydrated blended binders containing up to 24 % ceramic is carried out within the time period of 2 days to 28 days. The differential scanning calorimetry and thermogravimetry measurements are performed in the temperature range of 25°C to 1000°C in an argon atmosphere. The measurement of compressive strength is done according to the European standards for cement mortars. The thermal analysis results in the identification of temperature and quantification of enthalpy and mass changes related to the liberation of physically bound water, calcium-silicate-hydrates dehydration and portlandite, vaterite and calcite decomposition. The portlandite content is found to decrease with time for all blends which provides the evidence of the pozzolanic activity of ceramic powder even within the limited monitoring time of 28 days. Taking into account the favorable results obtained in the measurement of compressive strength, it can be concluded that the applied waste ceramic powder can be successfully used as a supplementary cementing material to Portland cement in an amount of up to 24 mass%.

  15. CALCIUM ORTHOPHOSPHATES HYDRATES: FORMATION, STABILITY AND INFLUENCE ON STANDARD PROPERTIES OF PORTLAND CEMENT

    Directory of Open Access Journals (Sweden)

    Kaziliunas A.

    2013-12-01

    Full Text Available Preparation of phosphogypsum to produce the binders requires a much higher input than preparation of natural gypsum stone. This makes it uncompetitive material. The investigations presented therein are meant to reduce this input by looking for the ways of rendering impurities harmless. Soluble acid orthophosphates are the main harmful impurity of phosphogypsum. The studies show that dry insoluble calcium orthophosphates hydrates (1.09 % and 2.18 % P2O5 in gypsum have little effect on W/C, setting times and soundness of Portland cement pastes. Insoluble calcium orthophosphates hydrates {CaHPO4∙2H2O, Ca8(HPO42(PO44∙5H2O and Ca9(HPO4(PO45(OH∙4H2O} formed in acidic medium (pH = 4.2 - 5.9 have been destroyed in alkaline medium and reduce standard compressive strength of cement up to 28 %. Calcium orthophosphates hydrates of hydroxyapatite group are stable in alcaline medium, while in dry state they reduce the standard compressive strength of cement until 10 %, but their suspensions prolong setting times of Portland cement as soluble orthophosphates – 2 - 3 times. Alkalis in cement increase pH of paste, but do not change the process of formation of calcium orthophosphates hydrates of hydroxyapatite group: it takes place through an intermediate phase - CaHPO4·2H2O, whose transformation into apatite lasts for 2 - 3 months.

  16. Microstructure Development and Transport Properties of Portland Cement-fly Ash Binary Systems: in view of service life predictions

    NARCIS (Netherlands)

    Yu, Z.

    2015-01-01

    Fly ash is a by-product of burning coal in electric power generating plants. It is commonly known that owing to its pozzolanic properties fly ash is widely used as a partial replacement for Portland cement in concrete. The use of fly ash in concrete not only reduces the landfill costs of fly ash, bu

  17. 78 FR 8493 - Foreign-Trade Zone 45-Portland, OR; Notification of Proposed Production Activity; SoloPower Inc...

    Science.gov (United States)

    2013-02-06

    ... Activity; SoloPower Inc. (Thin Film Photovoltaic Solar Panels); Portland, OR SoloPower Inc. (SoloPower) has... production of thin film photovoltaic solar panels. Pursuant to 15 CFR 400.14(b), FTZ activity would be... sourced from abroad include: Polymer film; diodes; conductive paste; junction boxes; sealant;...

  18. Contribución al estudio de los reacciones de hidratación del cemento portland por espectroscopia infrarroja

    Directory of Open Access Journals (Sweden)

    Vázquez Moreno, Tomás

    1976-09-01

    Full Text Available Not availableEn dos artículos anteriores (1 y (2 que figuran en los n.° 161 y 162 de esta Revista, respectivamente, se estudiaron, por medio de la espectroscopia IR, las fases del clinker y el cemento portland anhidro. Con el presente trabajo se da paso al estudio de los procesos de hidratación.

  19. ECIA, Chapter 1 Early Childhood Education Program in the Portland Public Schools. 1985-86 Evaluation Report.

    Science.gov (United States)

    Yagi, Kan

    This year-end evaluation report of the Chapter 1 Early Childhood Education (Preschool) Program in Portland (Oregon) Public Schools is a narrative supplement to the statistical forms used by Chapter 1 Education Consolidation Improvement Act (ECIA) evaluation and is organized into six sections: (1) introduction; (2) description of the program,…

  20. "Why Is This the Only Place in Portland I See Black People?": Teaching Young Children about Redlining

    Science.gov (United States)

    Johnson, Katharine

    2012-01-01

    As in many historically black neighborhoods in the United States, the gentrification of northeast Portland rests on an older history of economic injustice perpetrated by banks, realtors, governments, and white property owners. Redlining was one piece of an elaborate puzzle denying people of color access to housing and to wealth. The term refers to…

  1. Comparing the Environmental Impacts of Alkali Activated Mortar and Traditional Portland Cement Mortar using Life Cycle Assessment

    Science.gov (United States)

    Matheu, P. S.; Ellis, K.; Varela, B.

    2015-11-01

    Since the year 1908 there has been research into the use alkali activated materials (AAM) in order to develop cementitious materials with similar properties to Ordinary Portland Cement. AAMs are considered green materials since their production and synthesis is not energy intensive. Even though AAMs have a high compressive strength, the average cost of production among other issues limits its feasibility. Previous research by the authors yielded a low cost AAM that uses mine tailings, wollastonite and ground granulated blast furnace slag (GGBFS). This mortar has an average compressive strength of 50MPa after 28 days of curing. In this paper the software SimaPro was used to create a product base cradle to gate Life Cycle Assessment (LCA). This compared the environmental impact of the AAM mortar to an Ordinary Portland Cement mortar (PCHM) with similar compressive strength. The main motivation for this research is the environmental impact of producing Ordinary Portland Cement as compared to alkali activated slag materials. The results of this LCA show that the Alkali Activated Material has a lower environmental impact than traditional Portland cement hydraulic mortar, in 10 out of 12 categories including Global Warming Potential, Ecotoxicity, and Smog. Areas of improvement and possible future work were also discovered with this analysis.

  2. 76 FR 34252 - Notice Pursuant to the National Cooperative Research and Production Act of 1993; Portland Cement...

    Science.gov (United States)

    2011-06-13

    ... Cement Association Notice is hereby given that, on May 12, 2011, pursuant to Section 6(a) of the National Cooperative Research and Production Act of 1993, 15 U.S.C. 4301 et seq. (``the Act''), Portland Cement... specified circumstances. Specifically, Drake Cement, LLC, Scottsdale, AZ; Argos USA Corporation, Houston,...

  3. Arsenic Encapsulation Using Portland Cement With Ferrous Sulfate/Lime And Terra-BondTM Technologies - Microcharacterization And Leaching Studies

    Science.gov (United States)

    This work reports the results of an investigation on the treatment and encapsulation of arsenic-containing materials by Portland cement with ferrous sulfate and lime (PFL) and Terra-BondTM, a commercially available patented technology. The arsenic materials treated we...

  4. WOOD PRE-TREATMENT INFLUENCE ON THE HYDRATION OF PORTLAND CEMENT IN COMBINATION WITH SOME TROPICAL WOOD SPECIES

    Directory of Open Access Journals (Sweden)

    Nusirat Aderinsola SADIKU

    2014-06-01

    Full Text Available The influence of three pre-treatment methods on the hydration characteristics of Portland cement in combination with three tropical hardwood species was investigated. The maximum hydration temperature and time to reach maximum hydration temperature were analysed for the wood-cement-water mixtures of the three species after removing inhibitory extractives of wood samples by extraction with 5% Sodium hydroxide (NaOH, cold and hot water after removing inhibitory extractives of wood samples. There were differences in the hydration reaction of the wood species with Portland cement using the different pre-treatment methods. The compatibility of the wood species with Portland cement improved following pre-treatment. Sodium hydroxide pre-treatment had the most significant effect followed by hot water. Terminalia ivorensis (Idigbo, and Antiaris africana (Oriro species showed considerable improvement in their compatibility with Portland cement at 5% Sodium hydroxide pre-treatment with maximum hydration temperature of 65oC where Arere had 60.5oC where both cold and hot water were unable to raise the hydration temperature beyond 55.5oC . This study shows that the wood species requires more than cold and hot water extraction to make them suitable for wood cement composite materials as extraction with sodium hydroxide (1% solution was found to be the most effective treatment for the wood species under investigation.

  5. AVALIAÇÃO IN VITRO DA LIBERAÇÃO DE FLÚOR DE CIMENTOS DE IONÔMERO DE VIDRO E OUTROS MATERIAIS QUE CONTÊM FLÚOR

    OpenAIRE

    Terada, Raquel Sano Suga; Navarro,Maria Fidela de Lima; de CARVALHO, Ricardo Marins; Eulázio TAGA; FERNANDES Renata Bastos Del'Hoyo

    1998-01-01

    Este estudo avaliou in vitro, durante 28 dias, a propriedade de liberação de flúor de cimentos de ionômero de vidro (CIV) restauradores e outros materiais que contêm flúor. Os resultados mostraram que o padrão de liberação de flúor foi semelhante para todos os CIV testados, sendo que houve uma liberação inicial acentuada, seguida por um rápido declínio, tendendo a uma estabilização após 7 dias. Os CIV liberaram mais flúor do que uma resina composta e um selante de cicatrículas e fissuras. Den...

  6. Effectiveness of shrinkage-reducing admixtures on Portland pozzolan cement concrete

    Directory of Open Access Journals (Sweden)

    Videla, C.

    2005-06-01

    Full Text Available Drying shrinkage causes tensile stress in restrained concrete members. Since all structural elements are subject to some degree of restraint, drying shrinkage is regarded to be one of the main causes of concrete cracking. The purpose of the present study was to evaluate the effectiveness of SRA in reducing drying shrinkage strain in Portland pozzolan cement concrete. The major variables examined included slump, admixture type and dose, and specimen size. The measured results indicate that any of the admixtures used in the study significantly reduced shrinkage. Concrete manufactured with shrinkage reducing admixtures shrank an average of 43% less than concrete without admixtures. As a rule, the higher the dose of admixture, the higher was its shrinkage reduction performance. The experimental results were compared to the shrinkage strain estimated with the ACI 209, CEB MC 90, B3, GL 2000, Sakata 1993 and Sakata 2001 models. Although none of these models was observed to accurately describe the behaviour of Portland pozzolan cement concrete with shrinkage reducing admixtures, the Sakata 2001 model, with a weighted coefficient of variation of under 30%, may be regarded to be roughly adequate.

    La retracción por secado es un fenómeno intrínseco del hormigón que produce tensiones de tracción en elementos restringidos de hormigón. Puesto que todos los elementos presentan algún grado de retracción, se considera a la retracción por secado como una de las principales causas de agrietamiento en proyectos de construcción en hormigón. Por lo tanto, el objetivo de esta investigación fue evaluar la efectividad de los aditivos reductores de retracción (SRA en hormigones fabricados con cemento Portland puzolánico. Las variables principales estudiadas incluyen el asentamiento de cono de Abrams, marca y dosis de aditivo reductor de retracción, y tamaño de espécimen de hormigón. Los resultados obtenidos permiten concluir que el uso de

  7. Contribution to the determination of gypsum and hemihydrates content in Portland cements

    Directory of Open Access Journals (Sweden)

    Moreno Arús, Fernando

    1975-09-01

    Full Text Available Not availableLa mayoría de los técnicos de cemento, aceptan, que las anormalidades del fraguado, conocidas como "falso fraguado" en el cemento portland, se deben primordialmente a la presencia de yeso parcialmente deshidratado (S04Ca1/2H20. Si el clínker que se muele está enriquecido en cal libre, o la temperatura del molino es elevada (superior a los 110 °C o hay escasa ventilación de éste, se llega a originar una parcial deshidratación del yeso, que se mantiene durante el proceso de ensilado y que origina las anormalidades del fraguado al que anteriormente nos hemos referido. Por esta razón creemos muy importante poder conocer el grado de deshidratación en que se encuentra el yeso en un cemento.

  8. Effects of High Temperature on the Residual Performance of Portland Cement Concretes

    Directory of Open Access Journals (Sweden)

    Evandro Tolentino

    2002-09-01

    Full Text Available In this work we analyzed the "residual" performance of Portland cement concretes heat-treated at 600 °C after cooling down to room temperature. Concretes with characteristic compressive strength at 28 days of 45 MPa and of 60 MPa were studied. The heat-treatment was carried out without any imposed load. We measured the residual compressive strength and modulus of elasticity. The geometry of the structure was described by mercury intrusion porosimetry and nitrogen sorption tests. We observed a decrease of residual compressive strength and modulus of elasticity, with the raise of heat-treatment temperature, as a result of heat-induced material degradation. The results also indicated that the microstructural damage increased steadily with increasing temperature. Based on the results of this experimental work we concluded that residual mechanical properties of concrete are dependent of their original non heat-treated values.

  9. Pore size distribution, strength, and microstructure of portland cement paste containing metal hydroxide waste

    Energy Technology Data Exchange (ETDEWEB)

    Majid, Z.A.; Mahmud, H.; Shaaban, M.G.

    1996-12-31

    Stabilization/solidification of hazardous wastes is used to convert hazardous metal hydroxide waste sludge into a solid mass with better handling properties. This study investigated the pore size development of ordinary portland cement pastes containing metal hydroxide waste sludge and rice husk ash using mercury intrusion porosimetry. The effects of acre and the addition of rice husk ash on pore size development and strength were studied. It was found that the pore structures of mixes changed significantly with curing acre. The pore size shifted from 1,204 to 324 {angstrom} for 3-day old cement paste, and from 956 to 263 {angstrom} for a 7-day old sample. A reduction in pore size distribution for different curing ages was also observed in the other mixtures. From this limited study, no conclusion could be made as to any correlation between strength development and porosity. 10 refs., 6 figs., 3 tabs.

  10. Increasing the compressive strength of portland cement concrete using flat glass powder

    Energy Technology Data Exchange (ETDEWEB)

    Miranda Junior, Edson Jansen Pedrosa de; Bezerra, Helton de Jesus Costa Leite; Politi, Flavio Salgado; Paiva, Antonio Ernandes Macedo, E-mail: edson.jansen@ifma.edu.br [Instituto Federal de Educacao, Ciencia e Tecnologia do Maranha (IFMA), Sao Luis, MA (Brazil). Dept. de Mecanica e Materiais

    2014-08-15

    This paper analyzes the compressive strength of Portland cement concrete in response to the incorporation of 5%, 10% and 20% of flat glass powder in place of sand, at w/c (water/cement) ratios of 0.50, 0.55 and 0.58. A statistical analysis of variance (ANOVA) was performed after 7, 14 and 28 days of curing. The compressive strength test results indicate that the concrete containing a w/c ratio of 0.50 can be used for structural applications, regardless of the waste glass content, as can that with a w/c ratio of 0.55 containing 20% of waste glass. We suggest that the use of flat glass powder in place of sand in the above mentioned percentages is feasible for the production of an environmentally appropriate and structurally applicable concrete. However, the concrete's fluidity and void content must be taken into account. (author)

  11. Mechanical Properties and Microstructure of Portland Cement Concrete Prepared with Coral Reef Sand

    Institute of Scientific and Technical Information of China (English)

    WANG Qiankun; LI Peng; TIAN Yapo; CHEN Wei; SU Chunyi

    2016-01-01

    The feasibility of using coral reef sand (CRS) in Portland cement concrete is investigated by testing the mechanical property and microstructure of concrete. The composition, structure and properties of the CRS are analyzed. Mechanical properties and microstructure of concrete with CRS are studied and compared to concrete with natural river sand. The relationship between the microstructure and performance of CRS concrete is established. The CRS has a porous surface with high water intake capacity, which contributes to the mechanical properties of concrete. The interfacial transition zone between the cement paste and CRS is densiifed compared to normal concrete with river sand. Hydration products form in the pore space of CRS and interlock with the matrix of cement paste, which increases the strength. The total porosity of concrete prepared with CRS is higher than that with natural sand. The main difference in pore size distribution is the fraction of ifne pores in the range of 100 nm.

  12. Dielectric properties of portland cement paste as a function of time since mixing

    Science.gov (United States)

    Camp, Paul R.; Bilotta, Stephen

    1989-12-01

    The dielectric properties of portland cement paste and mortar have been measured in the frequency range 100 Hz-7 MHz as a function of time since mixing. Over much of the spectrum, the ac conductance of the samples appears directly related to the amount of unbound water remaining in the sample and ionic conduction predominates. In addition, interesting structure was found in both the conductance and capacitance data at high frequencies as the free water content was reduced. We conclude that relatively simple measurements of this kind can be a useful tool in concrete research and may provide the basis for simple, in situ, nondestructive measurement of the degree of curing of concrete or for monitoring water migration in concrete structures. Measurements on sealed samples of partially or fully cured concrete reveal also the water-cement ratio of the original mix.

  13. Standard Test Method for Bond Strength of Ceramic Tile to Portland Cement Paste

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2002-01-01

    1.1 This test method covers the determination of the ability of glazed ceramic wall tile, ceramic mosaic tile, quarry tile, and pavers to be bonded to portland cement paste. This test method includes both face-mounted and back-mounted tile. 1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  14. Lime kiln dust as a potential raw material in portland cement manufacturing

    Science.gov (United States)

    Miller, M. Michael; Callaghan, Robert M.

    2004-01-01

    In the United States, the manufacture of portland cement involves burning in a rotary kiln a finely ground proportional mix of raw materials. The raw material mix provides the required chemical combination of calcium, silicon, aluminum, iron, and small amounts of other ingredients. The majority of calcium is supplied in the form of calcium carbonate usually from limestone. Other sources including waste materials or byproducts from other industries can be used to supply calcium (or lime, CaO), provided they have sufficiently high CaO content, have low magnesia content (less than 5 percent), and are competitive with limestone in terms of cost and adequacy of supply. In the United States, the lime industry produces large amounts of lime kiln dust (LKD), which is collected by dust control systems. This LKD may be a supplemental source of calcium for cement plants, if the lime and cement plants are located near enough to each other to make the arrangement economical.

  15. Effects of Two Redispersible Polymer Powders on Efflorescence of Portland Cement-based Decorative Mortar

    Directory of Open Access Journals (Sweden)

    Huimei ZHU

    2014-09-01

    Full Text Available The effects of redispersible polymer powders of ethylene/Vinyl acetate copolymer (EVA and ethylene/vinyl laurate/vinyl chloride terpolymer (E/VL/VC on the efflorescence of Portland cement-based decorative mortar (PCBDM were studied. The results showed that EVA slightly prolongs the efflorescence duration of fresh PCBDM; and exacerbates efflorescence of hardened PCBDM, because it increases the content of soluble salts such as Ca2+, K+, Na+ ions in hardened PCBDM and promotes their migration. E/VL/VC exacerbates efflorescence of fresh PCBDM due to it easily dissolves in the surface water; but reduces efflorescence of hardened PCBDM, which is attributed to that it decreases the soluble salts content in hardened PCBDM and prohibits salts migration. DOI: http://dx.doi.org/10.5755/j01.ms.20.3.4053

  16. Influence of portland cement replacement in high calcium fly ash geopolymer paste

    Directory of Open Access Journals (Sweden)

    Tanakorn Phoo-ngernkham

    2014-03-01

    Full Text Available This article presents the influence of ordinary Portland cement (OPC replacement in high calcium fly ash (FA geopolymer paste. FA was used to replace OPC at the rate of 5, 10 and 15% by mass of binder. Sodium silicate (Na2SiO3 and 10 molar sodium hydroxide (NaOH solutions were used as the alkaline solution in the reaction. The Na2SiO3/NaOH ratio of 2.0 and the liquid/binder (L/B ratio of 0.60 were used in all mixtures. The results of increase OPC replacement, the setting time and compressive strain capacity decreased while the compressive strength and modulus of elasticity increased. The compressive strength and modulus of elasticity at 28 days of geopolymer pastes with 15% OPC replacement were 36.7 MPa and 13,300 MPa, respectively.

  17. Energy Edge Post-Occupancy Evaluation Project: The Dubal/Beck Office Building Portland, Oregon

    Energy Technology Data Exchange (ETDEWEB)

    1990-06-01

    The Workspace Satisfaction Survey measures occupant satisfaction with the thermal, lighting, acoustical, and air quality aspects of the work environment. In addition, to ratings of these ambient environmental features, occupants also rate their satisfaction with a number of functional aesthetic features of the office environment as well as their satisfaction with specific kinds of workspaces (e.g., computer rooms, the lobby, employee lounge, etc.) Each section on ambient conditions includes questions on the frequency with which people experience particular kinds of discomforts or problems, how much the discomfort bothers them, and how much it interferes with their work. Occupants are also asked to identify how they cope with discomfort or environmental problems, and to what extent these behaviors enable them to achieve more satisfactory conditions. This report documents the results of this survey of the occupants of the Dubal/Beck Office building, Portland, Oregon. 21 figs., 8 tabs.

  18. The effects of utilizing silica fume in Portland Cement Pervious Concrete

    Science.gov (United States)

    Mann, Daniel Allen

    Silica fume has long been used as a supplementary cementing material to provide a high density, high strength, and durable building material. Silica fume has a particle size a fraction of any conventional cement, which allows it to increase concrete strength by decreasing the porosity especially near the aggregates surface. Because Portland Cement Pervious Concrete (PCPC) has a smaller bond area between aggregate and paste, silica fume has significant impacts on the properties of the PCPC. The research in this paper studies the workability of a cement paste containing silica fume in addition to analyzing the results of testing on Portland Cement Pervious Concrete mixtures that also contained silica fume. Testing conducted included a study of the effects of silica fume on cement's rheological properties at various dosage rates ranging from zero to ten percent by mass. It was determined that silica fume has negligible effects on the viscosity of cement paste until a dosage rate of five percent, at which point the viscosity increases rapidly. In addition to the rheological testing of the cement paste, trials were also conducted on the pervious concrete samples. Sample groups included mixes with river gravel and chipped limestone as aggregate, washed and unwashed, and two different void contents. Workability tests showed that mixtures containing a silica fume dosage rate of 5 percent or less had comparable or slightly improved workability when compared to control groups. Workability was found to decrease at a 7 percent dosage rate. Samples were tested for compressive strength at 7 and 28 days and splitting tensile strength at 28 days. It was found in most sample groups, strength increased with dosage rates of 3 to 5 percent but often decreased when the dosage reached 7 percent. Abrasion testing showed that both samples containing washed aggregate and samples containing silica fume exhibited a reduced mass loss.

  19. Assessment of ferrous chloride and Portland cement for the remediation of chromite ore processing residue.

    Science.gov (United States)

    Jagupilla, Santhi C; Wazne, Mahmoud; Moon, Deok Hyun

    2015-10-01

    Chromite Ore Processing Residue (COPR) is an industrial waste containing up to 7% chromium (Cr) including up to 5% hexavalent chromium [Cr(VI)]. The remediation of COPR has been challenging due to the slow release of Cr(VI) from a clinker like material and thereby the incomplete detoxification of Cr(VI) by chemical reagents. The use of sulfur based reagents such as ferrous sulfate and calcium polysulfide to detoxify Cr(VI) has exasperated the swell potential of COPR upon treatment. This study investigated the use of ferrous chloride alone and in combination with Portland cement to address the detoxification of Cr(VI) in COPR and the potential swell of COPR. Chromium regulatory tests, X-ray powder diffraction (XRPD) analyses and X-ray absorption near edge structure (XANES) analyses were used to assess the treatment results. The treatment results indicated that Cr(VI) concentrations for the acid pretreated micronized COPR as measured by XANES analyses were below the New Jersey Department of Environmental Protection (NJDEP) standard of 20 mg kg(-1). The Toxicity characteristic leaching procedure (TCLP) Cr concentrations for all acid pretreated samples also were reduced below the TCLP regulatory limit of 5 mg L(-1). Moreover, the TCLP Cr concentration for the acid pretreated COPR with particle size ⩽0.010 mm were less than the universal treatment standard (UTS) of 0.6 mg L(-1). The treatment appears to have destabilized all COPR potential swell causing minerals. The unconfined compressive strength (UCS) for the treated samples increased significantly upon treatment with Portland cement.

  20. Corrosion of steel bars in cracked concrete made with ordinary portland, slag and fly ash cements

    Energy Technology Data Exchange (ETDEWEB)

    Mohammed, T.U.; Yamaji, T.; Hamada, H. [Port and Harbor Research Inst., Ministry of Land, Infrastructure and Transport (Japan); Aoyama, T. [PS Corp. (Japan)

    2001-07-01

    A study was conducted in which the marine durability of ordinary portland cement, slag and fly ash cement was examined using 15 year old plain and reinforced concrete cylindrical specimens. The performance of these cements was then examined for pre-cracked reinforced concrete prism samples. The process of manufacturing cement emits huge amounts of carbon dioxide into the global atmosphere. Replacing a portion of the cement with by-products from the steel industry and thermal power plants (which are both huge emitters of carbon dioxide) can lower carbon dioxide emissions and also solve the disposal issue of slag and fly ash while increasing the long-term durability of concrete structures. In this study, concrete cylindrical specimens were made of ordinary portland cement, slag and fly ash cements. The specimens were 100 x 100 x 600 mm prisms of different types of cement. Water-to-cement ratios were 0.45 and 0.55. Both tap water and seawater were used as mixing water. The samples were exposed in tidal pools for 15 years to evaluate the compressive strength of the concrete, corrosion of the steel bars, and chloride-ion concentrations in the concrete. It was shown that, with the exception of fly ash cements, the compressive strength of most cements increased after 15 years of exposure compared to its 28 day strength. Type C slag cement demonstrated the best performance against chloride-ion at the surface of concrete made with slag and fly ash. Voids in the steel-concrete interface make it possible for corrosion pits to develop. The use of seawater as mixing water results in earlier strength development at 28 days and does not cause to the strength of the concrete to regress after 15-years of exposure, but it causes more corrosion of steel bars at a lower cover depth. Corrosion of steel bars is not an issue at deeper cover depths. 15 refs., 19 tabs., 13 figs.

  1. Physical and mechanical characterization of Portland cement mortars made with expanded polystyrene particles addition (EPS

    Directory of Open Access Journals (Sweden)

    Ferrándiz-Mas, V.

    2012-12-01

    Full Text Available On this work the influence of the addition of different types (commercial and recycled and contents of expanded polystyrene on the physical and mechanical properties of Portland cement mortars has been studied. Variables studied are: workability, air content, bulk density, mechanical strength, porosity, water absorption and sound absorption. Mixtures have been also characterized by scanning electron microscopy. Air-entraining agents, water retainer and superplasticizer additives have been used in order to improve the workability of mortars. The results show that the workability and mechanical strength decreases with increasing content of expanded polystyrene. Additives improve the workability and porosity, allowing manufacture mortars with high levels of recycled material that show mechanical properties suitable for use as masonry mortars, stucco and plaster.

    El objetivo de este estudio es evaluar la influencia de la adición de distintos tipos y dosificaciones de poliestireno expandido, tanto comerciales como procedentes de reciclado, sobre las características físicas y mecánicas de morteros de cemento portland. Las variables estudiadas fueron: consistencia, aire ocluido, densidad aparente, resistencias mecánicas, porosidad, absorción de agua y absorción acústica. Los morteros también se han caracterizado por microscopia electrónica de barrido. Con objeto de mejorar la trabajabilidad de los morteros se ha empleado aditivos aireante, retenedor de agua y fluidificante. Los resultados muestran que al aumentar la cantidad de poliestireno expandido la trabajabilidad y las resistencias mecánicas disminuyen. El empleo de aditivos mejora la trabajabilidad y la porosidad, permitiendo fabricar morteros con altos contenidos de residuo, con propiedades mecánicas adecuadas para su empleo como morteros de albañilería, revoco y enlucido.

  2. Regenerative Portland cement sorbents for fluidized-bed combustion of coal

    Energy Technology Data Exchange (ETDEWEB)

    Albanese, A S; Sethi, D; Steinberg, M

    1980-01-01

    Portland cements are commercially available construction materials that contain high concentrations of calcium silicates. The silicates are highly reactive towards SO/sub 2/ at temperatures and pressures encountered in atmospheric and pressurized FBC's. Of the Portland cements tested, PC III appears to have the highest sulfation capacity when sulfated by SO/sub 2/ at FBC conditions. A thermodynamic analysis of the sulfation of calcium silicates indicates that they are capable of reducing the concentration of SO/sub 2/ in FBC combustion gases to within the current EPA emission limits. The optimum temperature for sulfation of 16/20 mesh PC III pellets is about 1000/sup 0/C in comparison to about 875/sup 0/ for natural limestones. The higher observed optimum temperature is an advantage because combustion and power cycle efficiencies tend to increase as bed temperature increases. The reactions for regenerating sulfated calcium silicates are similar to those for regenerating calcium sulfate. However, the equilibrium partial pressures of SO/sub 2/ in the reductive decomposition of sulfated silicates are much higher than for sulfate lime. This implies that higher SO/sub 2/ concentrations will be attainable in the regenerator off-gas which will result in more economical conversion of SO/sub 2/ to sulfur or sulfuric acid. The sulfation capacity and regeneration efficiency of PC III pellets do not deteriorate with repeated sulfation/regeneration cycling. This indicates that PC III pellets are suitable for use in regenerative systems. The sulfation capacity of PC III is independent of pressure up to at least 10 atm.

  3. Properties of SiMn slag as apozzolanic material in portland cement manufacture

    Directory of Open Access Journals (Sweden)

    Frías, M.

    2005-12-01

    Full Text Available The primary purpose of this study was to evaluate the behaviour of SiMn slag as a pozzolanic material in commercial Portland cement manufacture. This necessitated exploring different scientific and technical aspects to ensure a correct valuation. The results obtained revealed that silica and calcium are the main components of SiMn slag, whose pozzolanic activity occupies an intermediate position between silica fume and fly ash; it reduces heat of hydration and mortars made with cement containing SiMn slag exhibit compressive strength values similar to the figures for standard mortar. Consequently, the use of SiMn slag as an active addition to cement is feasible, inasmuch as the resulting product meets the requirements laid down in the present legislation.

    El objetivo principal de este trabajo es evaluar el comportamiento de la escoria de SiMn como material puzolánico en la fabricación de cementos Portland comerciales. Para ello, resulta necesario investigar diferentes aspectos científicos y técnicos que conlleven a una correcta valorización de las mismas. Los resultados obtenidos en el presente trabajo han puesto de manifiesto que la escoria de SiMn presenta una naturaleza sílico-cálcica, actividad puzolúnica intermedia entre el humo de sílice y ceniza volante, reduce el calor de hidratación y los morteros con escoria de SiMn muestra alcanzan resistencias a compresión similares a las del mortero patrón. Por lo tanto, la utilización de la escoria de SiMn como adición activa al cemento es viable, cumpliendo con las exigencias recogidas en la norma vigente.

  4. Development of a CE-QUAL-W2 temperature model for Crystal Springs Lake, Portland, Oregon

    Science.gov (United States)

    Buccola, Norman L.; Stonewall, Adam J.

    2016-05-19

    During summer 2014, lake level, streamflow, and water temperature in and around Crystal Springs Lake in Portland, Oregon, were measured by the U.S. Geological Survey and the City of Portland Bureau of Environmental Services to better understand the effect of the lake on Crystal Springs Creek and Johnson Creek downstream. Johnson Creek is listed as an impaired water body for temperature by the Oregon Department of Environmental Quality (ODEQ), as required by section 303(d) of the Clean Water Act. A temperature total maximum daily load applies to all streams in the Johnson Creek watershed, including Crystal Springs Creek. Summer water temperatures downstream of Crystal Springs Lake and the Golf Pond regularly exceed the ODEQ numeric criterion of 64.4 °F (18.0 °C) for salmonid rearing and migration. To better understand temperature contributions of this system, the U.S. Geological Survey developed two-dimensional hydrodynamic water temperature models of Crystal Springs Lake and the Golf Pond. Model grids were developed to closely resemble the bathymetry of the lake and pond using data from a 2014 survey. The calibrated models simulated surface water elevations to within 0.06 foot (0.02 meter) and outflow water temperature to within 1.08 °F (0.60 °C). Streamflow, water temperature, and lake elevation data collected during summer 2014 supplied the boundary and reference conditions for the model. Measured discrepancies between outflow and inflow from the lake, assumed to be mostly from unknown and diffuse springs under the lake, accounted for about 46 percent of the total inflow to the lake.

  5. Spectroscopic and microscopic characterization of portland cement based unleached and leached solidified waste

    Science.gov (United States)

    Salaita, Ghaleb N.; Tate, Philip H.

    1998-05-01

    In this study, portland cement based solidified/stabilized (S/S) waste and a cement-only control were studied before and after leaching. The solidified waste samples were prepared from a mix of organic-containing industrial waste sludge and portland cement. Toxicity characterization leaching procedure (TCLP) was the leaching test employed. The samples were studied using multi-surface analytical techniques including XPS, SIMS, XRD, FE-SEM and EDS. The data obtained from the various techniques show that leaching does not measurably affect the morphology or composition of the solidified waste sample. However, subtle changes in the composition of the cement control sample were observed. While the concentration of the elements observed on the surface of leached and unleached waste samples by XPS are very similar (except for Mg, Na and N), study of the corresponding cement samples exhibit differences in the level of C, Si, S, and Ca. The unleached cement sample shows lower levels of C and Si, but higher levels of O, S, Ca and Mg, indicating that leaching alters the cement sample. EDS analyses of the elemental composition of the bulk of the leached and unleached waste samples are similar, and also are similar for the leached and unleached cement samples, indicating that under the conditions of the TCLP test, leaching has no effect on the bulk. The high level of Ca present on the surface of the solidified waste indicates entrapment of the waste by the cement. The information and results obtained show that the surface analytical techniques used in this work, when combined with environmental wet methods, can provide a more complete picture of the concentration, chemical state and immobility of solidified waste.

  6. Crystallographic characterization of cement pastes hydrated with NaCl; Caracterizacao cristalografica de pastas de cimento hidratadas com NaCl

    Energy Technology Data Exchange (ETDEWEB)

    Melo, Carina Gabriela de Melo e; Martinelli, Antonio Eduardo; Melo, Dulce Maria Araujo; Melo, Marcus Antonio de Freitas; Melo, Vitor Rodrigo de Melo e [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

    2012-07-01

    One of the major current challenges faced by oil companies is the exploration of pre salt basins. Salt layers deposited upon the evaporation of ocean water and continental separation are mainly formed by NaCl and isolate immense oil reservoirs. The mechanical stability and zonal isolation of oil wells that run through salt layers must be fulfilled by cement sheaths saturated with NaCl to assure chemical compatibility between cement and salt layer. The present study aimed at evaluating the effect of NaCl addition on the hydration of oil well cement slurries as well as identifying the nature of crystalline phases present in the hardened cement. To that end, cement slurries containing NaCl were mixed, hardened and characterized by X-ray diffraction. The results revealed that the presence of NaCl affects the formation of hydration products by the presence of Friedel's salt. The intensity of the corresponding peaks increase as the contents of NaCl in the slurry increase. High concentrations of NaCl in Portland slurries increase the setting time of cement and the presence of Friedel's salt decreases the strength of the hardened cement. (author)

  7. Influence of Portland Cement Class on the Corrosion Rate of Steel Reinforcement in Cement Mortar Caused by Penetrating Chloride and Sulfate from the Environment

    OpenAIRE

    Bikić, F.; Cacan, M.; Rizvanović, M.

    2013-01-01

    The influence of portland cement class on the corrosion rate of steel reinforcement in cement mortar caused by penetrating chloride or sulfate from the environment in already hardened cement mortar is investigated in this paper. Three classes of portland cement have been used for the tests, PC 35, PC 45 and PC 55. Cylindrical samples of cement mortar with steel reinfor- cement in the middle were treated 6 months at room temperature in the follow...

  8. Estimated Depth to Ground Water and Configuration of the Water Table in the Portland, Oregon Area

    Science.gov (United States)

    Snyder, Daniel T.

    2008-01-01

    Reliable information on the configuration of the water table in the Portland metropolitan area is needed to address concerns about various water-resource issues, especially with regard to potential effects from stormwater injection systems such as UIC (underground injection control) systems that are either existing or planned. To help address these concerns, this report presents the estimated depth-to-water and water-table elevation maps for the Portland area, along with estimates of the relative uncertainty of the maps and seasonal water-table fluctuations. The method of analysis used to determine the water-table configuration in the Portland area relied on water-level data from shallow wells and surface-water features that are representative of the water table. However, the largest source of available well data is water-level measurements in reports filed by well constructors at the time of new well installation, but these data frequently were not representative of static water-level conditions. Depth-to-water measurements reported in well-construction records generally were shallower than measurements by the U.S. Geological Survey (USGS) in the same or nearby wells, although many depth-to-water measurements were substantially deeper than USGS measurements. Magnitudes of differences in depth-to-water measurements reported in well records and those measured by the USGS in the same or nearby wells ranged from -119 to 156 feet with a mean of the absolute value of the differences of 36 feet. One possible cause for the differences is that water levels in many wells reported in well records were not at equilibrium at the time of measurement. As a result, the analysis of the water-table configuration relied on water levels measured during the current study or used in previous USGS investigations in the Portland area. Because of the scarcity of well data in some areas, the locations of select surface-water features including major rivers, streams, lakes, wetlands, and

  9. Solidification of ion exchange resins saturated with Na+ ions: Comparison of matrices based on Portland and blast furnace slag cement

    Science.gov (United States)

    Lafond, E.; Cau dit Coumes, C.; Gauffinet, S.; Chartier, D.; Stefan, L.; Le Bescop, P.

    2017-01-01

    This work is devoted to the conditioning of ion exchange resins used to decontaminate radioactive effluents. Calcium silicate cements may have a good potential to encapsulate spent resins. However, certain combinations of cement and resins produce a strong expansion of the final product, possibly leading to its full disintegration. The focus is placed on the understanding of the behaviour of cationic resins in the Na+ form in Portland or blast furnace slag (CEM III/C) cement pastes. During hydration of the Portland cement paste, the pore solution exhibits a decrease in its osmotic pressure, which causes a transient expansion of small magnitude of the resins. At 20 °C, this expansion takes place just after setting in a poorly consolidated material and is sufficient to induce cracks. In the CEM III/C paste, swelling of the resins also occurs, but before the end of setting, and induces limited stress in the matrix which is still plastic.

  10. Structural Investigations of Portland Cement Components, Hydration, and Effects of Admixtures by Solid-State NMR Spectroscopy

    DEFF Research Database (Denmark)

    Skibsted, Jørgen Bengaard; Andersen, Morten D.; Jakobsen, Hans Jørgen

    2006-01-01

    for the C-S-H phase formed during hydration. It will be demonstrated that Al3+ and flouride guest-ions in the anhydrous and hydrated calcium silicates can be studied in detail by 27Al and 19F MAS NMR, thereby providing information on the local structure and the mechanisms for incorporation of these ions...... in the cement phases. The role of flouride ions is of special interest for mineralized Portland cements and it demonstrated that the location of these anions in anhydrous and hydrated Portland cements can be clarified using 19F MAS or 29Si{19F} CP/MAS NMR despite these cements contain only about 0.2 wt...

  11. Influence of Calcium Sulfate State and Fineness of Cement on Hydration of Portland Cements Using Electrical Measurement

    Institute of Scientific and Technical Information of China (English)

    WEI Xiaosheng; LI Zongjin; XIAO Lianzhen; THONG Wangfai

    2006-01-01

    The influence of calcium sulfate state and fineness of cement on hydration of Portland cement was studied using electrical resistivity measurement. The bulk resistivity curve of the paste from the abnormal cement mainly with hemihydrate had a characteristic abnormal peak and rapid increase in early period. The resistivity measurement technique can be used to discriminate abnormal setting. For normal cement with gypsum, the increase in fineness of the Portland cement decreases the minimum resistivity due to a higher ionic concentration and increases the 24 hour resistivity due to a reduction in macroscopic pore size. Thesetting time, compressive strength, pore structure of pastes made from different cements were carried out to compare the influence of water to cement ratio, calcium sulfate state and fineness. It is found that the electrical and mechanical properties are strongly affected by the initial porosity, the presence of hemihydrate or gypsum, and the fineness of cement.

  12. Effect of fly ash on the optimum sulfate of Portland Cement

    Science.gov (United States)

    Niemuth, Mark D.

    Calcium sulfate is typically added to ordinary portland cement (OPC) clinker during grinding to prevent flash set and to improve early-age strength development without causing volume instabilities. Recent changes to ASTM C150, Standard Specification for Portland Cement, have enabled greater flexibility in determining optimum sulfate levels in portland cement by not requiring ASTM C563, Approximation of Optimum SO3 in Hydraulic Cement Using Compressive Strength, to be used in setting sulfate target levels. ASTM C563 requires strength testing using only the hydraulic cement, which is not always indicative of the optimum sulfate for field use, since supplementary materials (e.g., fly ash) may be used by the concrete producer. Adding additional sulfate to account for the sulfate demand of fly ashes can enable an improvement in the early age strength for cement-fly ash systems and decrease in problems that may be attributed to OPC-admixture-fly ash incompatibility such as abnormal setting and slow strength gain. This thesis provides experimental data on the strength development and heat release during early hydration for cement-fly ash systems with different sulfate levels. The thesis focused on high calcium fly ashes, but low calcium fly ash was also tested. It is demonstrated that some fly ashes have their own sulfate demand and when these ashes are used in cement-fly ash blends there is effectively an increase in the optimal sulfate level that could be used for the OPC. It is also shown that optimum sulfate determined by heat of hydration measured with isothermal calorimetry is similar to the optimum sulfate determined by compressive strength at 1 day. Using isothermal calorimetry can result in substantial time and cost savings at plants for determining the optimal sulfate content. Theories for the mechanisms that drive the differences in sulfate demand in OPC are reviewed. These theories are adapted for OPC-fly ash blends and are outlined, tested and discussed. The

  13. Evolution and quantification of the main Sensitisers in commercial portland cements

    Directory of Open Access Journals (Sweden)

    Frías, M.

    2002-03-01

    Full Text Available The commercial Portland cements contain minor elements in their chemical compositions. The presence of these elements has a direct incidence in different aspects: rheological behaviour, reaction kinetics, environmental, etc. Some of them also have a negative effect on the human health; so, chromium (Cr, nickel (Ni and cobalt (Co are the main allergens present in Portland cements, causing of Professional Dermatitis in construction workers. The current study is focussed on the quantification of total and soluble chromium, nickel and cobalt in a wide range of Spanish commercial cements. These values can represent a contribution to the establishing of possible limitations or reductions of these elements in forthcoming standards. Analytical data show that clinkers are the main responsibles of the presence of soluble chromium in commercial cements. This fact could be indicating that chromium solubility (from inert Cr III to soluble Cr VI would be closely related to the clinkerisation conditions. On the other hand, there is not a direct ratio between total chromium and soluble chromium; it means that analytical results are punctual and not any case can be extrapolating ones. Ni and Co solubility in water is practically negligible either raw as clinkers.

    Los cementos Portland comerciales contienen elementos minoritarios en su composición química. La presencia de estos elementos tiene una incidencia directa en diferentes aspectos: comportamiento reológico, cinética de reacción, contaminación ambiental, etc. Algunos de ellos, aparte de su incidencia mencionada anteriormente, tienen un efecto negativo en la salud humana. Así, el cromo (Cr, níquel (Ni y cobalto (Co son los principales alérgenos contenidos en los cementos y, por lo tanto, los principales causantes de la Dermatitis Profesional. Este trabajo se centra en la cuantifîcación de los contenidos totales y solubles de cromo, níquel y cobalto presentes en los cementos comerciales

  14. Microstructure and mechanical properties of microwave-assisted heating of pozzolan-Portland cement paste at a very early stage

    OpenAIRE

    Natt Makul; Dinesh Kumar Agrawa

    2013-01-01

    Portland-pozzolan cement pastes at a very early stage subjecting to microwave heating were investigated. Microwave with a 2.45 GHz and multimode cavity was used for the experiments. The pastes containing pozzolan materials (pulverized fuel ash, metakaolin and silica fume) were proportioned with a 0.38 water/solid mass ratio and a 20% by weight replacement of total solid content. It was observed that the temperature increased continuously during microwave heating. Some ettringite rods and a...

  15. The most suitable techiniques and methods to identify high alumina cement and based portland cement in concretes

    OpenAIRE

    Blanco, M. T.; Puertas, F; Vázquez, T.; de la Fuente, A

    1992-01-01

    Instrumental techniques are indicated and the most adequated methodologies for determining the nature of the binder in concretes are explained. These methods are: a) Determination of the Silicic Moduli through chemical analysis of the sample. This test reveáis very different valúes between cement portland based concrete and high alumina cement based concretes. b) X-ray diffraction. It is considered as the best method. In the present paper the main diffraction Unes corresponding to...

  16. Combined effect of sodium sulphate and superplasticizer on the hydration of fly ash blended Portland® cement

    OpenAIRE

    Mukesh Kumar; Narendra Pratap Singh; Sanjay Kumar Singh; Nakshatra Bahadur Singh

    2010-01-01

    Combined effect of polycarboxylate type superplasticizer and sodium sulphate on the hydration of fly ash blended Portland® cement has been studied by using different techniques. Water consistency, setting times, non-evaporable water contents, water percolation, air contents, compressive strengths and expansion in corrosive atmosphere were determined. Hydration products were examined with the help of DTA and X-ray diffraction techniques. It is found that the superplasticizer reduces the pore s...

  17. Effects of composition and exposure on the solar reflectance of Portland cement concrete

    Energy Technology Data Exchange (ETDEWEB)

    Levinson, Ronnen; Akbari, Hashem

    2001-12-21

    Increasing the solar reflectance (albedo) of a paved surface keeps it cooler in the sun, reducing convection of heat from pavement to air and thereby decreasing the ambient air temperature. Simulations of the influence of pavement albedo on air temperature in Los Angeles predict that increasing the albedo of 1,250 km2 of pavement by 0.25 would save cooling energy worth $15M yr-1, and reduce smog-related medical and lost-work expenses by $76M yr-1. Most sidewalks and a small fraction of roads and parking areas are paved with portland cement concrete, which can be made quite reflective through suitable choice of cement and aggregate. Variations with composition and environmental exposure of the albedos of portland cement concrete pavements were investigated through laboratory fabrication and exposure of 32 mixes of concrete. Twenty-four mixes yielded substandard, ''rough'' concretes due to high, unmet aggregate water demand. The albedos of the remaining eight ''smooth'' concrete mixes ranged from 0.41 to 0.77 (mean 0.59). Simulated weathering, soiling, and abrasion each reduced average concrete albedo (mean decreases 0.06, 0.05, and 0.19, respectively), though some samples became slightly more reflective through weathering or soiling. Simulated rain (wetting) strongly depressed the albedos of concretes (mean decrease 0.23) until their surfaces were dried. Concrete albedo grew as the cement hydration reaction progressed (mean increase 0.08), but stabilized within six weeks of casting. White-cement concretes were on average significantly more reflective than gray-cement concretes. The albedo of the most-reflective white-cement concrete was 0.18 to 0.39 higher than that of the most-reflective gray-cement concrete, depending on state of exposure. Concrete albedo generally correlated with cement albedo and sand albedo, and, after abrasion, with rock albedo. Cement albedo had a disproportionately strong influence on the reflectance

  18. Demonstration Assessment of LED Roadway Lighting: NE Cully Boulevard Portland, OR

    Energy Technology Data Exchange (ETDEWEB)

    Royer, Michael P.; Poplawski, Michael E.; Tuenge, Jason R.

    2012-06-29

    A new roadway lighting demonstration project was initiated in late 2010, which was planned in conjunction with other upgrades to NE Cully Boulevard, a residential collector road in the northeast area of Portland, OR. With the NE Cully Boulevard project, the Portland Bureau of Transportation hoped to demonstrate different light source technologies and different luminaires side-by-side. This report documents the initial performance of six different newly installed luminaires, including three LED products, one induction product, one ceramic metal halide product, and one high-pressure sodium (HPS) product that represented the baseline solution. It includes reported, calculated, and measured performance; evaluates the economic feasibility of each of the alternative luminaires; and documents user feedback collected from a group of local Illuminating Engineering Society (IES) members that toured the site. This report does not contain any long-term performance evaluations or laboratory measurements of luminaire performance. Although not all of the installed products performed equally, the alternative luminaires generally offered higher efficacy, more appropriate luminous intensity distributions, and favorable color quality when compared to the baseline HPS luminaire. However, some products did not provide sufficient illumination to all areas—vehicular drive lanes, bicycle lanes, and sidewalks—or would likely fail to meet design criteria over the life of the installation due to expected depreciation in lumen output. While the overall performance of the alternative luminaires was generally better than the baseline HPS luminaire, cost remains a significant barrier to widespread adoption. Based on the cost of the small quantity of luminaires purchased for this demonstration, the shortest calculated payback period for one of the alternative luminaire types was 17.3 years. The luminaire prices were notably higher than typical prices for currently available luminaires

  19. Effects of occupational dust exposure on the health status of portland cement factory workers

    Directory of Open Access Journals (Sweden)

    R Manjula

    2013-07-01

    Full Text Available Introduction: Chronic exposure to Portland cement dust has been reported to lead to greater prevalence of various clinical conditions (includes both respiratory and non-respiratory. These conditions are consistently associated with the degree and duration of exposure. Regular use of appropriate personal protective equipment if made available at the work site could protect the cement factory workers from adverse health effects. Objective: To study the morbidity profile of the cement factory workers. Type of Study: Retrospective cohort study. Material and Methods: This study was conducted in the Portland Cement Factory in North Karnataka. Data was collected using predesigned questionnaire by personal interview method and clinical examination. A total of 64 male workers are randomly selected who are working in various departments like crushing, raw/cement mill, rotary kiln and packing department. Equal number of unexposed controls was selected from the area atleast 5 kms from the factory and those who are not exposed to cement dust in the past, who are matched for age, Socio economic status and smoking with the exposed population. Statistical Analysis: Chisquare test for qualitative data and unpaired t test for quantitative data using Epi info. Results: A total of 64 male workers and equal number of matched controls who are not exposed to the cement dust were included in the study. Among exposed maximum of 36% were employed in Crushing department, 25% each in Packing and cement/raw mill. Systolic and Diastolic blood pressure was found to be higher among the exposed, which is statistically highly significant (p<0.001. There is significant increase in weight among exposed (p<0.001. Maximum 29(45.3% of the workers had stuffy nose and epistaxis when compared to unexposed with Relative risk(RR of 2.6, followed by Dermatological complaints and lower respiratory complaints with RR of 2.18 and 2.3 respectively. Conclusion: Personal protective equipment

  20. Water dynamics in hardened ordinary Portland cement paste or concrete: from quasielastic neutron scattering.

    Science.gov (United States)

    Bordallo, Heloisa N; Aldridge, Laurence P; Desmedt, Arnaud

    2006-09-14

    Portland cement reacts with water to form an amorphous paste through a chemical reaction called hydration. In concrete the formation of pastes causes the mix to harden and gain strength to form a rock-like mass. Within this process lies the key to a remarkable peculiarity of concrete: it is plastic and soft when newly mixed, strong and durable when hardened. These qualities explain why one material, concrete, can build skyscrapers, bridges, sidewalks and superhighways, houses, and dams. The character of the concrete is determined by the quality of the paste. Creep and shrinkage of concrete specimens occur during the loss and gain of water from cement paste. To better understand the role of water in mature concrete, a series of quasielastic neutron scattering (QENS) experiments were carried out on cement pastes with water/cement ratio varying between 0.32 and 0.6. The samples were cured for about 28 days in sealed containers so that the initial water content would not change. These experiments were carried out with an actual sample of Portland cement rather than with the components of cement studied by other workers. The QENS spectra differentiated between three different water interactions: water that was chemically bound into the cement paste, the physically bound or "glassy water" that interacted with the surface of the gel pores in the paste, and unbound water molecules that are confined within the larger capillary pores of cement paste. The dynamics of the "glassy" and "unboud" water in an extended time scale, from a hundred picoseconds to a few nanoseconds, could be clearly differentiated from the data. While the observed motions on the picosecond time scale are mainly stochastic reorientations of the water molecules, the dynamics observed on the nanosecond range can be attributed to long-range diffusion. Diffusive motion was characterized by diffusion constants in the range of (0.6-2) 10(-9) m(2)/s, with significant reduction compared to the rate of diffusion

  1. Influence of bismuth oxide concentration on the pH level and biocompatibility of white Portland cement

    Directory of Open Access Journals (Sweden)

    Marina Angélica MARCIANO

    2014-07-01

    Full Text Available Objectives: To investigate if there is a relation between the increase of bismuth oxide and the decrease of pH levels and an intensification of toxicity in the Portland cement. Material and Methods: White Portland cement (WPC was mixed with 0, 15, 20, 30 and 50% bismuth oxide, in weight. For the pH level test, polyethylene tubes were filled with the cements and immersed in Milli-Q water for 15, 30 and 60 days. After each period, the increase of the pH level was assessed. For the biocompatibility, two polyethylene tubes filled with the cements were implanted in ninety albino rats (n=6. The analysis of the intensity of the inflammatory infiltrate was performed after 15, 30 and 60 days. The statistical analysis was performed using the Kruskal-Wallis, Dunn and Friedman tests for the pH level and the Kruskal-Wallis and Dunn tests for the biological analysis (p0.05. For the inflammatory infiltrates, no significant statistical differences were found among the groups in each period (p>0.05. The 15% WPC showed a significant decrease of the inflammatory infiltrate from 15 to 30 and 60 days (p<0.05. Conclusions: The addition of bismuth oxide into Portland cement did not affect the pH level and the biological response. The concentration of 15% of bismuth oxide resulted in significant reduction in inflammatory response in comparison with the other concentrations evaluated.

  2. Pacific lamprey (Entosphenus tridentatus) ammocoetes exposed to contaminated Portland Harbor sediments: Method development and effects on survival, growth, and behavior

    Science.gov (United States)

    Unrein, Julia R.; Morris, Jeffrey M.; Chitwood, Rob S.; Lipton, Joshua; Peers, Jennifer; van de Wetering, Stan; Schreck, Carl B.

    2016-01-01

    Many anthropogenic disturbances have contributed to the decline of Pacific lampreys (Entosphenus tridentatus), but potential negative effects of contaminants on lampreys are unclear. Lamprey ammocoetes are the only detritivorous fish in the lower Willamette River, Oregon, USA, and have been observed in Portland Harbor sediments. Their long benthic larval stage places them at risk from the effects of contaminated sediment. The authors developed experimental methods to assess the effects of contaminated sediment on the growth and behavior of field-collected ammocoetes reared in a laboratory. Specifically, they developed methods to assess individual growth and burrowing behavior. Burrowing performance demonstrated high variability among contaminated sediments; however, ammocoetes presented with noncontaminated reference sediment initiated burrowing more rapidly and completed it faster. Ammocoete reemergence from contaminated sediments suggests avoidance of some chemical compounds. The authors conducted long-term exposure experiments on individually held ammocoetes using sediment collected from their native Siletz River, which included the following: contaminated sediments collected from 9 sites within Portland Harbor, 2 uncontaminated reference sediments collected upstream, 1 uncontaminated sediment with characteristics similar to Portland Harbor sediments, and clean sand. They determined that a 24-h depuration period was sufficient to evaluate weight changes and observed no mortality or growth effects in fish exposed to any of the contaminated sediments. However, the effect on burrowing behavior appeared to be a sensitive endpoint, with potentially significant implications for predator avoidance.

  3. Pacific lamprey (Entosphenus tridentatus) ammocoetes exposed to contaminated Portland Harbor sediments: Method development and effects on survival, growth, and behavior.

    Science.gov (United States)

    Unrein, Julia R; Morris, Jeffrey M; Chitwood, Rob S; Lipton, Joshua; Peers, Jennifer; van de Wetering, Stan; Schreck, Carl B

    2016-08-01

    Many anthropogenic disturbances have contributed to the decline of Pacific lampreys (Entosphenus tridentatus), but potential negative effects of contaminants on lampreys are unclear. Lamprey ammocoetes are the only detritivorous fish in the lower Willamette River, Oregon, USA, and have been observed in Portland Harbor sediments. Their long benthic larval stage places them at risk from the effects of contaminated sediment. The authors developed experimental methods to assess the effects of contaminated sediment on the growth and behavior of field-collected ammocoetes reared in a laboratory. Specifically, they developed methods to assess individual growth and burrowing behavior. Burrowing performance demonstrated high variability among contaminated sediments; however, ammocoetes presented with noncontaminated reference sediment initiated burrowing more rapidly and completed it faster. Ammocoete reemergence from contaminated sediments suggests avoidance of some chemical compounds. The authors conducted long-term exposure experiments on individually held ammocoetes using sediment collected from their native Siletz River, which included the following: contaminated sediments collected from 9 sites within Portland Harbor, 2 uncontaminated reference sediments collected upstream, 1 uncontaminated sediment with characteristics similar to Portland Harbor sediments, and clean sand. They determined that a 24-h depuration period was sufficient to evaluate weight changes and observed no mortality or growth effects in fish exposed to any of the contaminated sediments. However, the effect on burrowing behavior appeared to be a sensitive endpoint, with potentially significant implications for predator avoidance. Environ Toxicol Chem 2016;35:2092-2102. © 2016 SETAC.

  4. Solidification/Stabilization of Fly Ash from a Municipal Solid Waste Incineration Facility Using Portland Cement

    Directory of Open Access Journals (Sweden)

    Qiang Tang

    2016-01-01

    Full Text Available This study investigated the solidification/stabilization of fly ash containing heavy metals using the Portland cement as a binder. It is found that both the cement/fly ash ratio and curing time have significant effects on the mechanical (i.e., compressive strength and leaching behaviors of the stabilized fly ash mixtures. When the cement/fly ash ratio increases from 4 : 6 to 8 : 2, the increase of compressive strength ratio raises from 42.24% to 80.36%; meanwhile, the leaching amount of heavy metals decreases by 2.33% to 85.23%. When the curing time increases from 3 days to 56 days, the compressive strength ratio of mixtures raises from 240.00% to 414.29%; meanwhile, the leaching amount of heavy metals decreases by 16.49% to 88.70%. The decrease of compressive strength with the lower cement/fly ash ratios and less curing time can be attributed to the increase of fly ash loading, which hinders the formation of ettringite and destroys the structure of hydration products, thereby resulting in the pozzolanic reaction and fixation of water molecules. Furthermore, the presence of cement causes the decrease of leaching, which results from the formation of ettringite and the restriction of heavy metal ion migration in many forms, such as C-S-H gel and adsorption.

  5. Plans and Living Practices for the Green Campus of Portland State University

    Directory of Open Access Journals (Sweden)

    Yoon Jung Choi

    2017-02-01

    Full Text Available This study aims to comprehend Portland State University (PSU’s green campus strategies, and students’ level of knowledge and living practices relating to green campus. PSU’s sustainable campus plan has been nationally and internationally recognized. A literature review, field investigation, and interviews were conducted to ascertain the PSU green campus strategies. This study also used a survey to understand students’ level of knowledge and practices. The survey results were analyzed by SPSS. Green campus projects at PSU were operated by official organizations and funded according to PSU’s long term plans in 12 multilateral categories: administration, energy, water, climate action, green buildings, green purchasing, waste reduction and recycling, food and dining services, transportation, land use, action, and education and student activity. The survey results show that the level of students’ understanding about PSU’s green campus strategies was somewhat low, but the amount of practice of a sustainable lifestyle was higher. Students who had taken courses related with sustainability or were engaged in sustainable activities had more knowledge about green campus strategies than students who had not. Therefore, it would be important to focus more on educating students and developing related programs in order to have more positive effects of green campus projects.

  6. INVESTIGATING EFFECTS OF INTRODUCTION OF CORNCOB ASH INTO PORTLAND CEMENTS CONCRETE: MECHANICAL AND THERMAL PROPERTIES

    Directory of Open Access Journals (Sweden)

    Antonio Price

    2014-01-01

    Full Text Available The purpose of this study was to evaluate the benefits of replacing Ordinary Portland Cement (OPC with Corncob Ash (CCA blended cements. The cement industry contributes considerable amount of Carbon Dioxide (CO2 emissions into the atmosphere. The main contribution of CO2 emissions from cement production results from the process of creating Calcium Oxide (CaO from limestone (CaCO3 commonly known as the calcination process. Blending OPC with a pozzolanic material will assist in the reduction of CO2 emissions due to calcination as well as enhance the quality of OPC. There are various pozzolanic materials such as fly ash, rice husk, silica fume and CCA that could be promising partial replacement for OPC. In this study, CCA will serve as the primary blending agent with OPC. An experiment was performed to designate an appropriate percentage replacement of CCA that would comply with specific standards of cement production. The experimental plan was designed to analyze compressive strength, workability and thermal performance of various CCA blended cements. The data from the experiment indicates that up to 10% CCA replacement could be used in cement production without compromising the structural integrity of OPC. In addition, it was found that the compressive strength and workability of the resulting concrete could be improved when CCA is added to the mixtures. Furthermore, it was shown that the introduction of 10% CCA can lead to significant reduction in thermal conductivity of the mixture.

  7. Effects of Using Pozzolan and Portland Cement in the Treatment of Dispersive Clay

    Directory of Open Access Journals (Sweden)

    A. H. Vakili

    2013-01-01

    Full Text Available Use of dispersive clay as construction material requires treatment such as by chemical addition. Treatments to dispersive clay using pozzolan and Portland cement, singly and simultaneously, were carried out in this study. When used alone, the optimum amount of pozzolan required to treat a fully dispersive clay sample was 5%, but the curing time to reduce dispersion potential, from 100% to 30% or less, was 3 month long. On the other hand, also when used alone, a 3% cement content was capable of reducing dispersion potential to almost zero percent in only 7 days; and a 2% cement content was capable of achieving similar result in 14 days. However, treatment by cement alone is costly and could jeopardize the long term performance. Thus, a combined 5% pozzolan and 1.5% cement content was found capable of reducing dispersion potential from 100% to zero percent in 14 days. The results indicate that although simultaneous treatment with pozzolan and cement would extend the required curing time in comparison to treatment by cement alone of a higher content, the task could still be carried out in a reasonable period of curing time while avoiding the drawbacks of using either pozzolan or cement alone.

  8. SUGARCANE BAGASSE ASH AS A PARTIAL-PORTLAND-CEMENT-REPLACEMENT MATERIAL

    Directory of Open Access Journals (Sweden)

    MARCOS OLIVEIRA DE PAULA

    2010-01-01

    Full Text Available Esta investigación se centra en la evaluación de los efectos de la sustitución parcial del cemento Portland por cenizas de bagazo de caña de azúcar (CBC en morteros. El objetivo principal fue encontrar un uso adecuado para este residuo agrícola que es generado en una cantidad cada vez mayor en Brasil, ya que el uso de CBC como un mineral mezclado en morteros y concretos, contribuye a disminuir el impacto ambiental de estos materiales relacionados con la producción de cemento. Técnicas experimentales fueron aplicadas tanto para la caracterización del CBC, como para la evaluación de su uso como una mezcla de minerales en los morteros, basados en pruebas físicas y mecánicas. Los resultados de las pruebas con morteros indicaron la viabilidad de la sustitución parcial del cemento por CBC, hasta en un 20%.

  9. Carbonation of low heat portland cement paste procured in water for different time

    Institute of Scientific and Technical Information of China (English)

    Deping Chen; Etsuo Sakai; Masaki Daimon; Yoko Ohba

    2007-01-01

    The carbonation technique was applied to accelerate the hydration of low heat portland cement (LHC). Before carbonation, the demoulded pastes were precured in water for 0, 2, 7, and 21 d, respectively. The results show that procuring time in water strongly influences the carbonation process. The phenolphthalein test indicates that the paste precured in water for a shorter time is more quickly carbonated than that for a longer time. The content of calcium hydroxide increases with increasing the procuring time in water, whereas, the amount of absorbed carbon dioxide changes contrarily. Scanning electron microscope (SEM) observation shows that portlandite always fills up big air bubbles in the paste during precuring in water, and the mercury intrusion porosimetry (MIP) results show that there are less large capillary pores in the paste precured in water for a longer time. It is found that the paste without precuring in water has more carbon dioxide absorption during curing in carbon dioxide atmosphere, and its total pore volume decreases remarkably with an increase in the carbonation time than that precured in water. X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) surface area analyses indicate that the carbonate products are vaterite and calcite; CxSHy,, formed from carbonation has low BET surface area in comparison with that of C-S-H formed from curing in water.

  10. Long-term Performance of Moderate Heat Portland Cement with Double-expansive Sources

    Institute of Scientific and Technical Information of China (English)

    YE Qing; CHEN Huxing; KONG Deyu; WANG Shangxian; LOU Zonghan

    2007-01-01

    The long-term performance of moderate heat Portland cement with double-expansive sources (DE cement) in the system of high MgO clinker and gypsum was studied by XRD, SEM/EDAX and test methods for strength and expansion of cement. Results indicate that the periclase particle, whose size was 5-7.5 μm in DE cement clinker containing 4.8 % MgO, existed individually. The periclase hydration in hardened DE cement paste started at about 60 days and completed up to 2 000 days, and ettringite in the paste was stable from 3 days to 2 000 days. Under the conditions of 4.5%-5.0 % MgO in clinker and 2.8%-3.4 %SO3 in cement,ettringite expansion and brucite expansion in DE cement paste had a continuity, entirety and stability. At the ages of 90, 365, 730 and 2 000 days the expansion of the paste reached 0.07%-0.11%, 0.16%-0.21%, 0.21%-0.27% and 0.29%-0.38 %, respectively. The results suggest that by using this cement in mass concrete it may compensate its temperature shrinkage and autogenous shrinkage to some extent.

  11. Radiopacity and cytotoxicity of Portland cement associated with niobium oxide micro and nanoparticles

    Directory of Open Access Journals (Sweden)

    Leticia Boldrin MESTIERI

    2014-12-01

    Full Text Available Objective Mineral Trioxide Aggregate (MTA is composed of Portland Cement (PC and bismuth oxide (BO. Replacing BO for niobium oxide (NbO microparticles (Nbµ or nanoparticles (Nbη may improve radiopacity and bioactivity. The aim of this study was to evaluate the radiopacity and cytotoxicity of the materials: 1 PC; 2 White MTA; 3 PC+30% Nbµ; 4 PC+30% Nbη. Material and Methods For the radiopacity test, specimens of the different materials were radiographed along an aluminum step-wedge. For cell culture assays, Saos-2 osteoblastic-cells (ATCC HTB-85 were used. Cell viability was evaluated through MTT assay, and bioactivity was assessed by alkaline phosphatase activity assay. Results The results demonstrated higher radiopacity for MTA, followed by Nbµ and Nbη, which had similar values. Cell culture analysis showed that PC and PC+NbO associations promoted greater cell viability than MTA. Conclusions It was concluded that the combination of PC+NbO is a potential alternative for composition of MTA.

  12. Properties of high calcium fly ash geopolymer pastes with Portland cement as an additive

    Science.gov (United States)

    Phoo-ngernkham, Tanakorn; Chindaprasirt, Prinya; Sata, Vanchai; Pangdaeng, Saengsuree; Sinsiri, Theerawat

    2013-02-01

    The effect of Portland cement (OPC) addition on the properties of high calcium fly ash geopolymer pastes was investigated in the paper. OPC partially replaced fly ash (FA) at the dosages of 0, 5%, 10%, and 15% by mass of binder. Sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) solutions were used as the liquid portion in the mixture: NaOH 10 mol/L, Na2SiO3/NaOH with a mass ratio of 2.0, and alkaline liquid/binder (L/B) with a mass ratio of 0.6. The curing at 60°C for 24 h was used to accelerate the geopolymerization. The setting time of all fresh pastes, porosity, and compressive strength of the pastes at the stages of 1, 7, 28, and 90 d were tested. The elastic modulus and strain capacity of the pastes at the stage of 7 d were determined. It is revealed that the use of OPC as an additive to replace part of FA results in the decreases in the setting time, porosity, and strain capacity of the paste specimens, while the compressive strength and elastic modulus seem to increase.

  13. Characteristics of Portland blast-furnace slag cement containing cement kiln dust and active silica

    Directory of Open Access Journals (Sweden)

    A. Abdel Rahman

    2016-09-01

    Full Text Available This investigation dealt with the effect of active silica, silica fume (SF or rice husk ash (RHA, on the mechanical and physico-chemical characteristics of the hardened blended cement pastes made of Portland blast-furnace slag cement (PSC containing cement kiln dust (CKD cured under normal conditions. Two blends made of PSC and CKD, improved by SF and two blends made of PSC and CKD improved by RHA were investigated. Hardened blended cement pastes were prepared from each cement blend by using water/cement ratio (W/C of 0.30 by weight and hydrated for various curing ages of 1, 3, 7, 28 and 90 days at the normal curing conditions under tap water at room temperature. Each cement paste was tested for its physico-chemical and mechanical characteristics; these characteristics include: compressive strength and kinetics of hydration. The phase composition of the formed hydration products was identified using X-ray diffraction (XRD and differential thermal analysis (DTA. It was found that the partial substitution of PSC by 10% and 15% of CKD is associated with an increase in the rate of hydration and a subsequent improvement of compressive strength of hardened PSC–CKD pastes. In addition, the replacement of PSC, in PSC–CKD blends, by 5% active silica was accompanied by further improvement of the physico-mechanical characteristics of the hardened PSC–CKD pastes.

  14. Stabilization/solidification of selenium-impacted soils using Portland cement and cement kiln dust.

    Science.gov (United States)

    Moon, Deok Hyun; Grubb, Dennis G; Reilly, Trevor L

    2009-09-15

    Stabilization/solidification (S/S) processes were utilized to immobilize selenium (Se) as selenite (SeO(3)(2-)) and selenate (SeO(4)(2-)). Artificially contaminated soils were prepared by individually spiking kaolinite, montmorillonite and dredged material (DM; an organic silt) with 1000 mg/kg of each selenium compound. After mellowing for 7 days, the Se-impacted soils were each stabilized with 5, 10 and 15% Type I/II Portland cement (P) and cement kiln dust (C) and then were cured for 7 and 28 days. The toxicity characteristic leaching procedure (TCLP) was used to evaluate the effectiveness of the S/S treatments. At 28 days curing, P doses of 10 and 15% produced five out of six TCLP-Se(IV) concentrations below 10mg/L, whereas only the 15% C in DM had a TCLP-Se(IV) concentration phases for all three soil-cement slurries were calcium selenite hydrate (CaSeO(3).H(2)O) and selenate substituted ettringite (Ca(6)Al(2)(SeO(4))(3)(OH)(12).26H(2)O), respectively.

  15. Analysis of Metal Contents in Portland Type V and MTA-Based Cements

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    Maura Cristiane Gonçales Orçati Dorileo

    2014-01-01

    Full Text Available The aim of this study was to determine, by Atomic Absorption Spectrometry (AAS, the concentration levels of 11 metals in Type V gray and structural white PC, ProRoot MTA, and MTA Bio. Samples, containing one gram of each tested cement, were prepared and transferred to a 100 mL Teflon tube with a mixture of 7.0 mL of nitric acid and 21 mL of hydrochloric acid. After the reaction, the mixture was filtered and then volumed to 50 mL of distilled water. For each metal, specific patterns were determined from universal standards. Arsenic quantification was performed by hydride generator. The analysis was performed five times and the data were statistically analyzed at 5% level of significance. Only the cadmium presented concentration levels of values lower than the quantification limit of the device. The AAS analysis showed increased levels of calcium, nickel, and zinc in structural white PC. Type V PC presented the greatest concentration levels of arsenic, chromium, copper, iron, lead, and manganese (P<0.05. Bismuth was found in all cements, and the lowest concentration levels were observed in Portland cements, while the highest were observed in ProRoot MTA. Both PC and MTA-based cements showed evidence of metals inclusion.

  16. Properties of steel foundry electric arc furnace dust solidified/stabilized with Portland cement.

    Science.gov (United States)

    Salihoglu, Guray; Pinarli, Vedat; Salihoglu, Nezih Kamil; Karaca, Gizem

    2007-10-01

    Electric arc furnace dust from steel production is generated in considerable amounts worldwide and needs to be treated as hazardous waste. The aim of this study was to investigate the properties of electric arc furnace dust solidified/stabilized by using Portland cement. Mortar and paste samples were prepared with varying waste-to-binder ratios between 0% and 90%. A comprehensive experimental program was designed including XRF characterization, setting time, unconfined compressive strength, and toxicity characteristics leaching procedure (TCLP), synthetic precipitation leaching procedure (SPLP), and acid neutralization capacity (ANC) tests. The results were evaluated in order to determine if the solidified /stabilized product can be disposed of at a landfill site with domestic waste or at a segregated landfill. The effect of using sand on S/S performance was also investigated. The results indicated that the solidification /stabilization process using PC helps the heavy metals to be bound in the cement matrix, but the TCLP leaching results exceeded the EPA landfilling limits. The SPLP leaching results conformed to the limits implying that the waste or S/S products can be disposed of at a segregated landfill; however the low ANC of the S/S products reveals that there may be leaching in the long-term. The sand used in the mortar samples adversely affected the S/S performance, causing higher heavy metal leaching levels, and lower pH levels in the leachate after the TCLP extraction than those measured in the leachate of the paste samples.

  17. Constitutive modeling of the aging viscoelastic properties of portland cement paste

    Science.gov (United States)

    Grasley, Zachary C.; Lange, David A.

    2007-12-01

    Analytical approaches for modeling aging viscoelastic behavior of concrete include the time-shift approach (analogous to time-temperature superposition), the solidification theory, and the dissolution-precipitation approach. The aging viscoelastic properties of concrete are generally attributed solely to the cement paste phase since the aggregates are typically linear elastic. In this study, the aging viscoelastic behavior of four different cement pastes has been measured and modeled according to both the time-shift approach and the solidification theory. The inability of each individual model to fully characterize the aging viscoelastic response of the materials provides insight into the mechanisms for aging of the viscoelastic properties of cement paste and concrete. A model that considers aging due to solidification in combination with inherent aging of the cement paste gel (modeled using the time-shift approach) more accurately predicted the aging viscoelastic behavior of portland cement paste than either the solidification or time-shift approaches independently. The results provide evidence that solidification and other intrinsic gel aging mechanisms are concurrently active in the aging process of cementitious materials.

  18. ESTUDIO SOBRE PASTAS Y MORTEROS DE CEMENTO PORTLAND CON REEMPLAZO POR LOZA SANITARIA

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    Silvina Zito

    2016-01-01

    Full Text Available En este trabajo se analiza el uso de Loza Sanitaria como reemplazo del cemento portland. Los reemplazos utilizados fueron 8, 24 y 40 % en peso; los ensayos empleados contemplaron la evolución de la hidratación desde los primeros minutos (hasta 48 horas a través de la calori metría , y a partir de los dos días (hasta 28 días por medio de la velocidad de fijación del hidróxido de calcio, el agua químicamente combinada, la resistencia mecánica a flexión y a compresión y la porosidad. Los resultados mostraron que a medida que aum enta el porcentaje de reemplazo, a las primeras edades d el efecto de dilución solapa y se contrapone con el de estimulación física ; y a la edad de 28 días todas las mezclas presentan además de la estimulación física también la química , por la reactividad puzolánica.

  19. The impact of sulphate and magnesium on chloride binding in Portland cement paste

    Energy Technology Data Exchange (ETDEWEB)

    De Weerdt, K., E-mail: klaartje.d.weerdt@ntnu.no [Department of Structural Engineering, Norwegian University of science and Technology, Trondheim (Norway); SINTEF Building and Infrastructure, Trondheim (Norway); Orsáková, D. [Department of Civil Engineering, Technical University of Brno, Brno (Czech Republic); Geiker, M.R. [Department of Structural Engineering, Norwegian University of science and Technology, Trondheim (Norway)

    2014-11-15

    The effect of magnesium and sulphate present in sea water on chloride binding in Portland cement paste was investigated. Ground well hydrated cement paste was exposed to MgCl{sub 2}, NaCl, NaCl + MgCl{sub 2}, MgSO{sub 4} + MgCl{sub 2} and artificial sea water solutions with a range of concentrations at 20 °C. Chloride binding isotherms are determined and pH of the solutions were measured. A selection of samples was examined by SEM-EDS to identify phase changes upon exposure. The experimental data were compared with calculations of a thermodynamic model. Chloride binding from sea water was similar to chloride binding for NaCl solutions. The magnesium content in the sea water lead to a slight decrease in pH, but this did not result in a notable increase in chloride binding. The sulphate present in sea water reduces both chloride binding in C–S–H and AFm phases, as the C–S–H incorporates more sulphates instead of chlorides, and part of the AFm phases converts to ettringite.

  20. Modeling of Hydration, Compressive Strength, and Carbonation of Portland-Limestone Cement (PLC Concrete

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    Xiao-Yong Wang

    2017-01-01

    Full Text Available Limestone is widely used in the construction industry to produce Portland limestone cement (PLC concrete. Systematic evaluations of hydration kinetics, compressive strength development, and carbonation resistance are crucial for the rational use of limestone. This study presents a hydration-based model for evaluating the influences of limestone on the strength and carbonation of concrete. First, the hydration model analyzes the dilution effect and the nucleation effect of limestone during the hydration of cement. The degree of cement hydration is calculated by considering concrete mixing proportions, binder properties, and curing conditions. Second, by using the gel–space ratio, the compressive strength of PLC concrete is evaluated. The interactions among water-to-binder ratio, limestone replacement ratio, and strength development are highlighted. Third, the carbonate material contents and porosity are calculated from the hydration model and are used as input parameters for the carbonation model. By considering concrete microstructures and environmental conditions, the carbon dioxide diffusivity and carbonation depth of PLC concrete are evaluated. The proposed model has been determined to be valid for concrete with various water-to-binder ratios, limestone contents, and curing periods.

  1. Effects of using pozzolan and Portland cement in the treatment of dispersive clay.

    Science.gov (United States)

    Vakili, A H; Selamat, M R; Moayedi, H

    2013-01-01

    Use of dispersive clay as construction material requires treatment such as by chemical addition. Treatments to dispersive clay using pozzolan and Portland cement, singly and simultaneously, were carried out in this study. When used alone, the optimum amount of pozzolan required to treat a fully dispersive clay sample was 5%, but the curing time to reduce dispersion potential, from 100% to 30% or less, was 3 month long. On the other hand, also when used alone, a 3% cement content was capable of reducing dispersion potential to almost zero percent in only 7 days; and a 2% cement content was capable of achieving similar result in 14 days. However, treatment by cement alone is costly and could jeopardize the long term performance. Thus, a combined 5% pozzolan and 1.5% cement content was found capable of reducing dispersion potential from 100% to zero percent in 14 days. The results indicate that although simultaneous treatment with pozzolan and cement would extend the required curing time in comparison to treatment by cement alone of a higher content, the task could still be carried out in a reasonable period of curing time while avoiding the drawbacks of using either pozzolan or cement alone.

  2. Characterization of Moroccan coal waste: valorization in the elaboration of the Portland clinker

    Directory of Open Access Journals (Sweden)

    Belkheiri D.

    2014-04-01

    Full Text Available Coal exploited in the mine of Jerada (northeast of Morocco was accompanied by large quantities of waste. The purpose of this work is to characterize this waste with the aim of its use as a material for civil engineering. Mineral and chemical investigations on this waste in the raw state, and at different temperature of heat treatments, were carried out by various methods: X-ray fluorescence, X-ray diffraction, infrared spectroscopy. These analyzes showed that the studied waste, contain essentially a mineral part formed by silica and various clays, as well as coal’s residues. The thermal investigation of waste, by differential scanning calorimetry (DSC, revealed an exothermic phenomenon attributed to the combustion of coal residues. Other phenomena were noted on the thermograms due to the mineral part transformations. In this analysis a comparison was also made with pure coal. These characteristics of coal waste encourage studying its development in reducing energy consumption in the Portland cement manufacture. Mixtures of waste with limestone or with raw cement materials were studied, and the resulting products were analyzed by different methods.

  3. Degradation of Alumina and Magnesia Chrome refractory bricks in Portland cement kiln – Corrected version*

    Directory of Open Access Journals (Sweden)

    Ben Addi K.

    2014-05-01

    Full Text Available In cement plants, the refractory products are particularly confronted to partially liquid oxide phases at temperature ranging between 900°C and 1700°C. All constituents of these products have to resist not only to thermal constraints, but also to the thermochemical solicitations which result from contact material/coating. In order to study the phenomenon of degradation of refractory bricks in cement kilns and to identify the causes of their degradation, we proceed to the examination of industrial cases in cement kiln. Many chemical tests of the degraded refractory bricks have been done and the results acquired were compared to the ones not used. The analysis of the results is doing using different techniques (Loss of ignition, X-ray Fluorescence, X-ray Diffraction. The results show that the degradation of the used bricks in the clinkering and cooling zone is due to the infiltration of aggressive elements such us sulphur, alkali (Na2O, K2O .... The chemical interaction between the Portland clinker phases and refractory material has also an importance on the stability of the coating and consequently on the life of the refractories.

  4. Relation between the Rheology Characteristic and Initial Hydration Structure of Portland Cement

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Based on the rheology characteristic and the resistivity variation under alternating electric-field of Portland cement hydration by means of AR2000 advanced rheometer and non-contacting electrical resistivity device, the influence of cement kinds and the chemical admixtures on the initial rheology characteristic and structure forming and developing of cement hydration was studied. The relationship between the rheology characteristic, the initial hydration structure forming and the hydration process at very early ages was analyzed by macro properties and microstructure tests. The results showed that, the storage modulus, acted as S, could be described more subtle distinction accompanying with hydration of fresh paste model at very early period. Combining the resistivity alterations, a sudden change on structure forming emerged when the hydration of cement becoming inducing age. The rheology characteristic was interrelated to the hydration structure forming, development and the physical mechanics properties. The sudden change on storage modulus moved up due to the addition of retarder, but the structure forming and developing was retarded to a certain extent.

  5. A Binder of Phosphogypsum-Ground Granulated Blast Furnace Slag-Ordinary Portland Cement

    Institute of Scientific and Technical Information of China (English)

    HUANG Yun; LIN Zongshou

    2011-01-01

    A new hydraulic cementitious binder was developed by mainly utilizing industrial byproducts phosphogypsum (PG) and ground granulated blast furnace slag (GGBFS) with small addition of ordinary portland cement (OPC). The hydration process and microstructure were studied by X-ray diffraction (XRD)and scanning electronic microscopy (SEM). OPC hydrated first at early age to form primarily C-S-H gel, ettringite and calcium hydroxide (CH). GGBFS activated by CH and sulfate ions hydrated continuously at later age, producing more and more hydration products, C-S-H gel and ettringite. Thus the paste developed a denser microstructure and its strength increased. The 28 d compressive strength of the mixture of 50% PG, 46% GGBFS and 4% OPC exceeded 45 MPa. The setting time was faster and 3 d and 7 d strength were higher when the proportion of OPC increased. But the 28 d strength decreased when OPC exceeded 4% due to large amount of ettringite formed at late hydration age which damaged the microstructure.

  6. Microstructure and Composition of Hydration Products of Ordinary Portland Cement with Ground Steel-making Slag

    Institute of Scientific and Technical Information of China (English)

    LI Yong-xin; CHEN Yi-min; ZHANG Hong-tao; HE Xing-yang; WEI Jiang-xiong; ZHANG Wen-sheng

    2003-01-01

    The effect of ground steel-making slag on microstructure and composition of hydration products of ordinary Portland cement (OPC) was investigated by mercury intrusion porosimetry ( MIP ), X- ray diffraction (XRD) and differential thermal analysis (DTA). Results show that ground steel-making slag is a kind of high activity mineral additives and it can raise the longer-age strength of OPC mortar. The total porosity and average pore diameter of OPC paste with groand steel-making slag increase with the increase of the amount of ground steelmaking slag replacing OPC at various ages, while after 28 days most pores in OPC paste with ground steel-making slag do not influeace the strength because the diameter of those pores is in the rang of 20 to 50nm. The hydration mechanism of ground steel-making slag is similar to that of OPC but different from that of fly ash and blast furnace slag. The hydration products of ground steel-making slag contain quite a lot of Ca( OH)2 in long age.

  7. Monitoring accelerated carbonation on standard Portland cement mortar by nonlinear resonance acoustic test

    Science.gov (United States)

    Eiras, J. N.; Kundu, T.; Popovics, J. S.; Monzó, J.; Borrachero, M. V.; Payá, J.

    2015-03-01

    Carbonation is an important deleterious process for concrete structures. Carbonation begins when carbon dioxide (CO2) present in the atmosphere reacts with portlandite producing calcium carbonate (CaCO3). In severe carbonation conditions, C-S-H gel is decomposed into silica gel (SiO2.nH2O) and CaCO3. As a result, concrete pore water pH decreases (usually below 10) and eventually steel reinforcing bars become unprotected from corrosion agents. Usually, the carbonation of the cementing matrix reduces the porosity, because CaCO3 crystals (calcite and vaterite) occupy more volume than portlandite. In this study, an accelerated carbonation-ageing process is conducted on Portland cement mortar samples with water to cement ratio of 0.5. The evolution of the carbonation process on mortar is monitored at different levels of ageing until the mortar is almost fully carbonated. A nondestructive technique based on nonlinear acoustic resonance is used to monitor the variation of the constitutive properties upon carbonation. At selected levels of ageing, the compressive strength is obtained. From fractured surfaces the depth of carbonation is determined with phenolphthalein solution. An image analysis of the fractured surfaces is used to quantify the depth of carbonation. The results from resonant acoustic tests revealed a progressive increase of stiffness and a decrease of material nonlinearity.

  8. Evolución de la Porosidad de Pastas de Cemento Portland por la Incorporación de una Puzolana Natural Evolution of Porosity in Portland Cement Pastes by addition of Natural Pozzolan

    OpenAIRE

    J. L. Fernández; González, E.L.; Brown, S.A.; O.R. Batic

    2004-01-01

    Se ha determinado la evolución que se produce en la porosidad de las pastas elaboradas con cemento Portland para uso general (CPN IRAM 50000), al incorporarle una puzolana natural de la región, en distintas proporciones y en función del tiempo de curado. El ensayo de porosidad se realiza según Norma API-RP-40, basada en la ley de Boyle, por la cual se determina el volumen de los vacíos de las pastas. Este se determina por diferencia entre el volumen total del gas a una presión P1 de 6.9.10(5)...

  9. Habitat Restoration and Monitoring in Urban Streams: The Case of Tryon Creek in Portland, OR

    Science.gov (United States)

    Rios Touma, B. P.; Prescott, C.; Axtell, S.; Kondolf, G. M.

    2013-12-01

    Habitat enhancement in urban streams can be important for threatened species but challenging, because of altered catchment hydrology and urban encroachment on floodplains and channel banks. In Portland (OR) restoration actions have been undertaken at the watershed scale (e.g.: storm water management, protection of sites with high watershed value) to improve water quality, and at reach scale, when water quality and quantity are adequate, to increase habitat heterogeneity and stabilize banks. To evaluate reach-scale restoration projects in the Tryon Creek watershed, we sampled benthic macroinvertebrates and conducted habitat quality surveys pre-project and over 4 years post- project. Species sensitive to pollution and diversity of trophic groups increased after restoration. Although taxonomical diversity increased after restoration, but was still low compared to reference streams. We found no significant changes in trait proportions and functional diversity. Functional diversity, proportion of shredders and semivoltine invertebrates were significantly higher in reference streams than the restored stream reaches. We hypothesized that inputs of coarse particulate organic matter and land use at watershed scale may explain the differences in biodiversity between restored and reference stream reaches. Variables such as substrate composition, canopy cover or large wood pieces did not change from pre- to post-project, so could not explain the changes in the community. This may have been partly attributable to insensitivity of the visual estimate methods used, but likely also reflects an importance influence of watershed variables on aquatic biota - suggesting watershed actions may be more effective for the ecological recovery of streams. For future projects, we recommend multihabitat benthic sampling supported by studies of channel geomorphology to better understand stream response to restoration actions.

  10. Glycerol Salicylate-based Pulp-Capping Material Containing Portland Cement.

    Science.gov (United States)

    Portella, Fernando Freitas; Collares, Fabrício Mezzomo; Santos, Paula Dapper; Sartori, Cláudia; Wegner, Everton; Leitune, Vicente Castelo Branco; Samuel, Susana Maria Werner

    2015-01-01

    The purpose of this study was to evaluate the water sorption, solubility, pH and ability to diffuse into dentin of a glycerol salicylate-based, pulp-capping cement in comparison to a conventional calcium hydroxide-based pulp capping material (Hydcal). An experimental cement was developed containing 60% glycerol salicylate resin, 10% methyl salicylate, 25% calcium hydroxide and 5% Portland cement. Water sorption and solubility were determined based on mass changes in the samples before and after the immersion in distilled water for 7 days. Material discs were stored in distilled water for 24 h, 7 days and 28 days, and a digital pHmeter was used to measure the pH of water. The cement's ability to diffuse into bovine dentin was assessed by Raman spectroscopy. The glycerol salicylate-based cement presented higher water sorption and lower solubility than Hydcal. The pH of water used to store the samples increased for both cements, reaching 12.59 ± 0.06 and 12.54 ± 0.05 after 7 days, for Hydcal and glycerol salicylate-based cements, respectively. Both cements were able to turn alkaline the medium at 24 h and sustain its alkalinity after 28 days. Hydcal exhibited an intense diffusion into dentin up to 40 µm deep, and the glycerol salicylate-based cement penetrated 20 µm. The experimental glycerol salicylate-based cement presents good sorption, solubility, ability to alkalize the surrounding tissues and diffusion into dentin to be used as pulp capping material.

  11. Storm runoff as related to urbanization in the Portland, Oregon-Vancouver, Washington Area

    Science.gov (United States)

    Laenen, Antonius

    1980-01-01

    A series of equations was developed to provide a better method of determining flood frequencies in the Portland-Vancouver urban area than is now available. The resulting regression equations can be used to compute peak discharge and storm runoff with a standard error of estimate of approximately 30 percent. Basins used to define the regression equations ranged in size from 0.2 to 26 square miles. Those physical basin parameters that proved to be significant are: drainage area, effective impervious area, storage, rainfall intensity, basin slope, and soil infiltration. The equations indicate that total urbanization of an undeveloped basin can increase peak discharge as much as 3? times and almost double the volume of storm runoff. Impervious area, as delineated by mapping techniques, proved to be an inadequate physical parameter for use in the regression equations because builders and planners have devised many methods of routing storm runoff from impervious areas to the main channel (in effect, speeding up or slowing down the response to the storm). In some parts of the study area, storm runoff was diverted into dry wells and never entered the main channel. To define the effect of this rerouting, the digital model was used to find an effective impervious area that would 'best fit' the rainfall-runoff data. Field estimates to verify the effectiveness of the impervious area for two of the basins showed that optimizations were within 20 percent of those shown by the digital model. Users of these data who may find the effective impervious area a difficult, expensive, and time-consuming parameter to obtain have an alternative. The combination of land-use type I (parks, forests, and vacant lots) and Type II (agriculture) proved to be an excellent inverse indicator of impervious area. Land-use types I and II, coupled with the street-gutter density, an indication of effective routing, provide the user with alternative indices of urbanization.

  12. The effect of portland cement for solidification of soils contaminated by mine tailings containing heavy metals

    Science.gov (United States)

    Jian-Jun, Chen; Zheng-Miao, Xie

    2010-05-01

    Portland cement(PC) was used to solidify the lead-zinc mine tailings contaminated soils(CS) in this work. The soils were heavily polluted by heavy metals with lead(up to 19592 mg/kg), zinc(up to 647mg/kg), Cd(up to 14.65mg.kg) and Cu(up to 287mg/kg). Solidified/stabilized(s/s)forms with a range of cement contents, 40-90 wt%, were evaluated to determine the optimal binder content. Unconfined compression strength test(UCS), Chinese solid waste-extraction procedure for leaching toxicity - Horizontal vibration method, toxicity characteristic leaching procedures(TCLP) were used for physical and chemical characterization of the s/s forms. The procedure of Tessier et al.(1979) was used to separate S/S forms Pb, Zn, Cd, Cu into different fractions. The results show that addition of 50% cement was enough for the s/s forms to satisfy the MU10 requirements (0.10 MPa). Under the 50% addition, the content of the water-exchangeable fraction of Pb reduced from 2.25% to 0.2%, the carbonate-bound fraction and organic-bound fraction reduced by about half, while the Fe-Mn oxide-bound fraction was more than doubled. The residual fraction decreased 8% on the contrary. For Zn, except for the carbonate-bound fraction increased slightly, the features of other items were same as that of Pb. For Cd, the water-exchangeable fraction was reduced largely, the residual fraction and Fe-Mn oxide-bound fraction increased 2-3%. For Cu, A distinct feature is the organic-bound fraction reduced with the reduction in consumption of cement, at the same time, the residual fraction increased corresponding. Leaching test results indicate that the leaching contents of Pb2+ of the six specimens are quite different at low pH value(

  13. Prospection of Portland cement raw material: A case study in the Marmara region of Turkey

    Science.gov (United States)

    Özgüner, A. M.

    2014-09-01

    Representative sampling of the raw materials used to make Portland cement, correct calculations for the possible clinker mixtures, sufficient reserves of the raw materials and selection of the correct infrastructure for the location of a cement factory are essential to the protection of the great investment in the factory. The results of chemical analyses of pipe samples taken in the field at right angles to the strikes of favourable limestone, clay, shale, and marl outcrops were used in Kind's lime saturation formula for clinker calculations of the possible mixtures. The cement modulus values were calculated using the corresponding clinker oxide ratios and were confirmed to be within the standard intervals for positive cement raw material mixtures. The most promising raw material source, a double lithologic mixture of limestone and mudstone was found during the prospection in north of Bilecik Province, where rhyolitic tuff outcrops with pozzolanic properties also exist. Some marble quarries nearby have been inclined to dispose of their marble wastes for use in cement production to prevent polluting the environment with them. The nearby Gemlik fertiliser factory provides inexpensive waste gypsum that can be used as a cool cement mixing material. The limestone, mudstone and trass raw material reserves in this area were calculated to be sufficient for the factory's requirements for more than 100 years of operation as results of the detailed geological mapping. The regional infrastructure is most suitable for distribution and marketing of cement products. The cement factory described in this study has been producing cement for the last 3 years, after coring and testing of the raw material reserves.

  14. Stabilization/solidification of selenium-impacted soils using Portland cement and cement kiln dust

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Deok Hyun, E-mail: dmoon10@hotmail.com [W.M. Keck Geoenvironmental Laboratory, Center for Environmental Systems, Stevens Institute of Technology, Hoboken, NJ 07030 (United States); Department of Environmental Engineering, Chosun University, Gwangju 501-759 (Korea, Republic of); Grubb, Dennis G. [W.M. Keck Geoenvironmental Laboratory, Center for Environmental Systems, Stevens Institute of Technology, Hoboken, NJ 07030 (United States); Schnabel Engineering, LLC, 510 East Gay Street, West Chester, PA 19380 (United States); Reilly, Trevor L. [W.M. Keck Geoenvironmental Laboratory, Center for Environmental Systems, Stevens Institute of Technology, Hoboken, NJ 07030 (United States)

    2009-09-15

    Stabilization/solidification (S/S) processes were utilized to immobilize selenium (Se) as selenite (SeO{sub 3}{sup 2-}) and selenate (SeO{sub 4}{sup 2-}). Artificially contaminated soils were prepared by individually spiking kaolinite, montmorillonite and dredged material (DM; an organic silt) with 1000 mg/kg of each selenium compound. After mellowing for 7 days, the Se-impacted soils were each stabilized with 5, 10 and 15% Type I/II Portland cement (P) and cement kiln dust (C) and then were cured for 7 and 28 days. The toxicity characteristic leaching procedure (TCLP) was used to evaluate the effectiveness of the S/S treatments. At 28 days curing, P doses of 10 and 15% produced five out of six TCLP-Se(IV) concentrations below 10 mg/L, whereas only the 15% C in DM had a TCLP-Se(IV) concentration <10 mg/L. Several treatments satisfied the USEPA TCLP best demonstrated available technology (BDAT) limits (5.7 mg/L) for selenium at pozzolan doses up to 10 times less than the treatments that established the BDAT. Neither pozzolan was capable of reducing the TCLP-Se(VI) concentrations below 25 mg/L. Se-soil-cement slurries aged for 30 days enabled the identification of Se precipitates by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM)-energy dispersive X-ray spectroscopy (EDX). XRD and SEM-EDX analyses of the Se(IV)- and Se(VI)-soil-cement slurries revealed that the key selenium bearing phases for all three soil-cement slurries were calcium selenite hydrate (CaSeO{sub 3}.H{sub 2}O) and selenate substituted ettringite (Ca{sub 6}Al{sub 2}(SeO{sub 4}){sub 3}(OH){sub 12}.26H{sub 2}O), respectively.

  15. Waste brick's potential for use as a pozzolan in blended Portland cement.

    Science.gov (United States)

    Lin, Kae-Long; Chen, Bor-Yann; Chiou, Chyow-San; An Cheng

    2010-07-01

    This study investigated the pozzolanic reactions and engineering properties of waste brick-blended cements in relation to various replacement ratios (0-50%). The waste brick consisted of SiO(2) (63.21%), Al(2)O(3) (16.41%), Fe(2)O(3) (6.05%), Na(2)O (1.19%), K(2)O (2.83%) and MgO (1.11%), and had a pozzolanic activity index of 107%. The toxic characteristic leaching procedure (TCLP) results demonstrate that the heavy-metal content in waste bricks met the Environmental Protection Agency regulatory limits. Experimental results indicate that 10, 20, 30, 40 and 50% of cement can be replaced by waste brick, which causes the initial and final setting times to increase. Compressive strength development was slower in waste brick-blended cement (WBBC) pastes in the early ages; however, strength at the later ages increased significantly. Species analyses demonstrate that the hydrates in WBBC pastes primarily consisted of Ca(OH)(2) and calcium silicate hydrate (C-S-H) gel, like those found in ordinary Portland cement (OPC) paste. Pozzolanic reaction products formed in the WBBC pastes, in particular, various reaction products, including hydrates of calcium silicates (CSH), aluminates (CAH) and aluminosilicates (CASH), formed as expected, resulting in consumption of Ca(OH)(2) during the late ages of curing. The changes in the properties of WBBC pastes were significant as blend ratio increased, due to the pores of C-S-H gels and CAH filling via pozzolanic reactions. This filling of gel pores resulted in densification and subsequently enhanced the gel/space ratio and degree of hydration. Experimental results demonstrate waste brick can be supplementary cementitious material.

  16. OBTENTION D’UN CLINKER PORTLAND CONSOMMANT PEU D’ENERGIE

    Directory of Open Access Journals (Sweden)

    L Kacimi

    2007-06-01

    Full Text Available L’objectif de notre travail consiste à diminuer la température de cuisson du clinker Portland par l'ajout de minéralisateurs dans le mélange des matières premières. Une série de composés chimiques purs, de matières naturelles et de déchets industriels ont été additionnés séparément aux mélanges crus de trois cimenteries algériennes (Zahana, Béni-Saf et Chlef. La plupart de ces additifs, avec un pourcentage ne dépassant pas 4% du mélange, ont pu diminuer la température de clinkerisation à 1300 °C. Leurs effets sur les propriétés hydrauliques du clinker sont cependant différents. Ceci est lié à la composition minéralogique et la structure des minéraux du clinker synthétisé. Les déchets industriels et les fluorures ont présenté une grande efficacité dans la baisse de la température de cuisson. Le phosphogypse et NaF ont amélioré la cristallisation des minéraux du clinker en formant un taux élevé d’alite. Ces caractéristiques expliquent l’amélioration des propriétés physiques et mécaniques de ce clinker.

  17. Precipitation Intensity Trend Detection using Hourly and Daily Observations in Portland, Oregon

    Directory of Open Access Journals (Sweden)

    Alexis Cooley

    2017-02-01

    Full Text Available The intensity of precipitation is expected to increase in response to climate change, but the regions where this may occur are unclear. The lack of certainty from climate models warrants an examination of trends in observational records. However, the temporal resolution of records may affect the success of trend detection. Daily observations are often used, but may be too coarse to detect changes. Sub-daily records may improve detection, but their value is not yet quantified. Using daily and hourly records from 24 rain gages in Portland, Oregon (OR, trends in precipitation intensity and volume are examined for the period of 1999–2015. Daily intensity is measured using the Simple Daily Intensity Index, and this method is adapted to measure hourly scale intensity. Kendall’s tau, a non-parametric correlation coefficient, is used for monotonic trend detection. Field significance and tests for spatial autocorrelation using Moran’s Index are used to determine the significance of group hypothesis tests. Results indicate that the hourly data is superior in trend detection when compared with daily data; more trends are detected with hourly scale data at both the 5% and 10% significance levels. Hourly records showed a significant increase in 6 of 12 months, while daily records showed a significant increase in 4 of 12 months at the 10% significance level. At both scales increasing trends were concentrated in spring and summer months, while no winter trends were detected. Volume was shown to be increasing in most months experiencing increased intensity, and is a probable driver of the intensity trends observed.

  18. Characterization via nuclear magnetic resonance of Portland cement and related materials

    Science.gov (United States)

    Edwards, Christopher Lane

    The physicochemical and engineering performance properties of several API class G and H ordinary Portland cements (OPCs) from various foreign and domestic sources have been investigated. The engineering performance properties are found to vary from sample to sample, and sources for this variation were sought out and identified. Magic angle spinning (MAS) 29Si nuclear magnetic resonance (NMR) experiments were marked by unusual relaxation behavior due to paramagnetism inherent in OPCs. A model system was created to mimic the paramagnetism of the cements and the system's relaxation behavior was analyzed. The iron in the calcium aluminoferrite (C4AF) provides the paramagnetism sufficient to substantially increase the relaxation rates of the 29Si in the tricalcium silicate (C3S) and dicalcium silicate (C2S) of cement. Several relaxation techniques were evaluated for analyzing cement relaxation, and saturation recovery was identified as the preferred technique. Correlations of data from the saturation recovery experiments with engineering performance properties, especially the strength development of cement pastes, were obtained facilely. An error analysis of the NMR and engineering performance testing techniques was conducted, which indicated that NMR measurements produced less error than the engineering performance tests. A best practice, modified from the saturation recovery experiment, is proposed for use in property correlations. Additionally, 13C MAS NMR was used to characterize various fluorinated single-walled carbon nanotubes (F-SWNTs), which proved surprisingly effective in attenuating 13C-19F dipolar interactions and quantifying the extent of functionalization present at high degrees of reaction. The mixed-metal nanocluster known as FeMoC was also characterized by MAS NMR. The impact of the paramagnetic Fe3+ in the Keplerate cage on the 31P nuclei in the caged Keggin ion of FeMoC was evident in the greatly reduced relaxation times measured.

  19. Vibrational study on the bioactivity of Portland cement-based materials for endodontic use

    Science.gov (United States)

    Taddei, P.; Tinti, A.; Gandolfi, M. G.; Rossi, P. L.; Prati, C.

    2009-04-01

    The bioactivity of a modified Portland cement (wTC) and a phosphate-doped wTC cement (wTC-P) was studied at 37 °C in Dulbecco's Phosphate Buffered Saline (DPBS). The cements, prepared as disks, were analysed at different ageing times (from 1 day to 2 months) by micro-Raman and ATR/FT-IR spectroscopies. The presence of deposits on the surface of the cements and the composition changes as a function of the storage time were investigated. The presence of an apatite deposit on the surface of both cements was already revealed after one day of ageing in DPBS. The trend of the I 965/I 991 Raman intensity ratio indicated the formation of a meanly thicker apatite deposit on the wTC-P cement at all the investigated times. This result was confirmed by the trend of the I 1030/I 945 IR intensity ratio calculated until 14 days of ageing. At 2 months, the thickness of the apatite deposit on wTC and wTC-P was about 200 and 500 μm, respectively, as estimated by micro-Raman spectroscopy, confirming the higher bioactivity of the phosphate-doped cement. Vibrational techniques allowed to gain more insights into the cement transformation and the different hydration rates of the various cement component. The setting of the cement and the formation of the hydrated silicate gel (C-S-H phase) was spectroscopically monitored through the I 830/I 945 IR intensity ratio.

  20. Use of Variamine Blue dye in Spectrophotometric determination of Water Soluble Cr(VI in Portland Cement

    Directory of Open Access Journals (Sweden)

    Devesh K. Sharma

    2015-12-01

    Full Text Available Variamine blue dye as chromogenic reagent was used for Portland cement samples in determination of soluble hexavalent chromium. This method was based on the reaction of Cr(VI with potassium iodide in acidic medium to liberate iodine, which oxidized variamine blue to form a violet colored species having an absorption maximum 556 nm. The extraction of soluble Cr(VI for quantification in cement was done according to European method. The validity of this method was thoroughly examined by comparing with standard DPC method as well as the accuracy of the method was checked using a standard reference material of National Institute of Standards & Technology (NIST, USA.

  1. Design and manufacture of Portland cement - application of sensitivity analysis in exploration and optimisation Part II. Optimisation

    DEFF Research Database (Denmark)

    Svinning, K.; Høskuldsson, Agnar

    2006-01-01

    A program for a model-based optimisation has been developed. The program contains two subprograms. The first one does minimising or maximising constrained by one original PLS-component or one equal to a combination of several. The second one does searching for the optimal combination of PLS......-components, which gives max or min y. The program has proved to be applicable for achieving realistic results for implementation in the design of Portland cement with respect to performance and in the quality control during production....

  2. Applications of solid-state Nuclear Magnetic Resonance (NMR) in studies of Portland cements-based materials

    DEFF Research Database (Denmark)

    Skibsted, Jørgen; Andersen, Morten Daugaard; Jakobsen, Hans Jørgen

    2007-01-01

    Solid-state NMR spectroscopy represents an important research tool in the characterization of a range of structural properties for cement-based materials. Different approaches of the technique can be used to obtain information on hydration kinetics, mobile and bound water, porosity, and local...... atomic structures. After a short introduction to these NMR techniques, it is exemplified how magic-angle spinning (MAS) NMR can provide quantitative and structural information about specific phases in anhydrous and hydrated Portland cements with main emphasis on the incorporation of Al3+ ions...

  3. Estudo comparativo da infiltração marginal em restaurações de classe V

    Directory of Open Access Journals (Sweden)

    FARIAS Débora Gonçalves de

    2002-01-01

    Full Text Available Este estudo teve como objetivo avaliar o comportamento laboratorial de adesivos dentinários, cimentos ionoméricos modificados por resina e resinas compostas modificadas por poliácidos, no selamento das margens gengivais de cavidades de classe V preparadas na junção amelocementária. Quarenta cavidades foram executadas nas faces vestibular e palatina/lingual de 20 terceiros molares humanos extraídos, e restauradas com os seguintes materiais: grupo 1 (G1- Vitremer (3M; grupo 2 (G2- Vitremer (3M e Syntac Sprint/Tetric Ceram (Vivadent; grupo 3 (G3- Syntac Sprint/Tetric Ceram (Vivadent; grupo 4 (G4- Prime & Bond 2.1/Variglass (Dentsply. Após termociclagem em corante azul de metileno, os espécimes foram seccionados longitudinalmente e analisados em lupa estereoscópica para avaliação do grau de infiltração marginal. Os resultados após teste estatístico de Mann-Whitney revelaram melhor vedamento marginal para o grupo 1, quando comparado com o grupo 4 (p = 0,05, mas não foram demonstradas diferenças significantes entre os demais grupos. Nas condições desse experimento, o material Vitremer ofereceu melhor vedamento marginal que o sistema Prime & Bond 2.1/Variglass.

  4. Avaliação da variação de pH e da permeabilidade da dentina cervical em dentes submetidos ao tratamento clareador

    Directory of Open Access Journals (Sweden)

    Dezotti Mariela S. G.

    2002-01-01

    Full Text Available A reabsorção cervical externa da raiz é uma das desvantagens do procedimento clareador. Vários são os mecanismos que podem ser responsáveis por desencadear esta reabsorção, dentre eles, a ação química e física dos materiais utilizados, bem como a morfologia da junção amelocementária. Este trabalho teve como objetivo observar uma possível via de comunicação entre a câmara pulpar e a superfície externa da raiz, medindo o pH e a infiltração de corante na dentina cervical após o procedimento clareador. Realizou-se o tratamento endodôntico em 34 dentes incisivos permanentes. Os dentes foram divididos em 3 grupos experimentais de acordo com o nível do corte da obturação e selamento da embocadura dos canais com cimento de ionômero de vidro. O clareamento foi realizado usando perborato de sódio e peróxido de hidrogênio a 30%. As leituras do pH foram realizadas após 30 min, 24 h, 48 h e 72 h do início do procedimento. A seguir, os dentes foram imersos em fucsina básica a 0,5% por 24 h para determinarmos possíveis diferenças na permeabilidade da dentina cervical. Os resultados mostraram que o pH apresentou tendência a se modificar quando o corte da obturação permaneceu na embocadura dos canais, bem como quando se removeram 2 mm da obturação e quando se selou a embocadura com cimento de ionômero de vidro. A permeabilidade dentinária aumentou nos 3 grupos experimentais, em comparação com os dentes que compreenderam o grupo controle. Estas leves diferenças podem sugerir uma via de comunicação entre a câmara pulpar e a superfície externa da raiz.

  5. Effect of saliva and blood contamination on the bi-axial flexural strength and setting time of two calcium-silicate based cements: Portland cement and biodentine.

    Science.gov (United States)

    Alhodiry, W; Lyons, M F; Chadwick, R G

    2014-03-01

    This study evaluated the effect of contamination with saliva and blood on the bi-axial flexural strength and setting time of pure gray Portland cement and Biodentine (Septodont, Allington, UK). A one-way ANOVA showed that contamination caused no significant difference between the cements in bi-axial flexural strength (P> 0.05). However there was a significant difference in setting time (Pcement taking longer than Biodentine, regardless of the contaminant, and contamination with blood increased the setting time of both materials. Biodentine was similar in strength to Portland cement, but had a shorter setting time for both contaminated and non-contaminated samples.

  6. Avaliação in vitro da resistência de união à tração de três tipos de pinos de fibra cimentados a raízes bovinas com diferentes cimentos resinosos

    OpenAIRE

    Mayra Zamboni Quintero

    2012-01-01

    Este estudo teve como objetivo avaliar, através de testes de tração, a resistência de união de pinos pré-fabricados, com diferentes graus de translucidez, à dentina bovina, utilizando três tipos de cimentos resinosos. Noventa incisivos bovinos tiveram suas coroas anatômicas separadas das raízes através de uma secção perpendicular ao longo eixo dos dentes na junção amelocementária, de modo que as raízes apresentassem 14 mm de comprimento. Os condutos radiculares foram tratados endodonticamente...

  7. MASSA ESPECÍFICA APARENTE E REAL E POROSIDADE DE GRÃOS DE CAFÉ EM FUNÇÃO DO TEOR DE UMIDADE

    Directory of Open Access Journals (Sweden)

    Sandra Maria Couto

    1999-04-01

    Full Text Available RESUMO Esta pesquisa foi desenvolvida com o objetivo de se obter valores para algumas características físicas do café, necessárias ao desenvolvimento de unidades de separação aerodinâmicas e ao dimensionamento de secadores e silos. Investigou-se o efeito do teor de umidade nos valores da massa específica real e aparente, e nos da porosidade de grão de café das variedades Catuaí e Timor. Os grãos, colhidos em dois estádios de maturação (verde e cereja foram submetidos a um processo de secagem em terreiro de cimento; trabalhou-se com dois lotes de café da variedade Catuaí, colhidos em épocas diferentes e a época de colheita não produziu alterações relevantes nos valores das massas específicas real e aparente; por outro lado, a massa específica real do café aumenta com acréscimos na umidade do grão, enquanto a massa específica aparente decresce. Os valores para essas massas são menores que aqueles para a maioria dos grãos agrícolas; entretanto, a porosidade de ambas encontra-se na mesma faixa de valores.

  8. Quantitative determination of tricalcicum aluminate in portland cement by X-ray diffraction

    Directory of Open Access Journals (Sweden)

    Sagrera Moreno, José Luis

    1989-06-01

    Full Text Available Tricalcium aluminate (C3A is one of the constitutive phase of the cement-clinker. Its concentration influences the cement behaviour in sulphate aggressive soils. Therefore its quantification is very convenient and International standards fix its content when the concrete is used in contact with soils or liquids containing sulphate compounds. There are two possibilities in order to calculate the amount of C3A in clinker phases: one consist in a mathematical calculation from the results of the chemical analysis (Bogue formulae and the order is based in X-ray diffraction, using the height of the representative peak of the C3A phase. In the present note, the experimental procedure in order to determine the C3A content from X-ray test is presented.

    El aluminato tricáicico es una de las fases constitutivas del clinker de cemento portland. Su concentración en el cemento influye en el comportamiento de éste, en las obras sometidas a la posible agresividad de diferentes sulfatos cuando entran en contacto con las estructuras que se fabrican con él. Por ello la determinación de su concentración es un dato que puede invalidar su uso en una obra. De ahí que las normas internacionales fijen la cantidad de aluminato tricáicico según se clasifique la agresividad del entorno en el que una estructura será colocada. Existen fórmulas matemáticas para calcular la concentración de cada una de las fases del clinker a partir de las concentraciones de los elementos químicos de clinker expresados en forma de óxidos. Los posibles errores en los análisis químicos producen errores en los cálculos de las concentraciones de cada fase. Para determinar la concentración de dichas fases se puede emplear también la técnica de difracción de rayos X, basándose en la medida de la altura del pico representativo de la fase que se quiere determinar.

  9. Microscopic air void analysis of hardened Portland cement concrete by the isolated shadow technique

    Science.gov (United States)

    Harris, Basil Mark

    The Isolated Shadow Technique is an image processing and analysis procedure for identifying and characterizing surface voids dispersed on an otherwise flat plane of heterogeneous solids. The objective of the Isolated Shadow Technique is to capture, process, and analyze images of a flat surface in which all of the features, save the boundary outlines of any surface voids, are eliminated. In short, the technique utilizes a series of digital images of the subject planar surface; where each image of the series is subjected to a unique lighting condition. By positioning the lights such that the shadows cast into the craters vary between images, these variations can be sequestered and the edges of the voids can subsequently be reconstructed from the isolated shadows. The primary purpose of this work was the development of the Isolated Shadow Technique for the particular application of quantitatively describing the microscopic voids in hardened Portland cement concrete. The Isolated Shadow System was developed for this application of the technique. The hardware and software of the system are described and the function is demonstrated. The system was found to have an average accuracy of 2.7% with a maximum deviation of 5.0% when compared to physical measurements. The results of polished sections of concrete specimens characterized by the Isolated Shadow System are compared to the results obtained with the commonly used standard methods (ASTM C 457; A and B). The coefficients of variation of parameters calculated to describe the air-void system (according to the ASTM C 457 formulations) are shown to be in the neighborhood of one percent when the observed test area includes at least 7,830 mmsp2 of polished concrete (with paste contents ranging from approximately 28% to 32%). The sensitivity of the air-void system parameters (as computed by the system) to changes in magnification and mosaic size are evaluated. A critical analysis of the underlying assumptions of the ASTM C

  10. Low-cost computer classification of land cover in the Portland area, Oregon, by signature extension techniques

    Science.gov (United States)

    Gaydos, Leonard

    1978-01-01

    Computer-aided techniques for interpreting multispectral data acquired by Landsat offer economies in the mapping of land cover. Even so, the actual establishment of the statistical classes, or "signatures," is one of the relatively more costly operations involved. Analysts have therefore been seeking cost-saving signature extension techniques that would accept training data acquired for one time or place and apply them to another. Opportunities to extend signatures occur in preprocessing steps and in the classification steps that follow. In the present example, land cover classes were derived by the simplest and most direct form of signature extension: Classes statistically derived from a Landsat scene for the Puget Sound area, Wash., were applied to the Portland area, Oreg., using data for the next Landsat scene acquired less than 25 seconds down orbit. Many features can be recognized on the reduced-scale version of the Portland land cover map shown in this report, although no statistical assessment of its accuracy is available.

  11. Assessment of the interaction of Portland cement-based materials with blood and tissue fluids using an animal model

    Science.gov (United States)

    Schembri Wismayer, P.; Lung, C. Y. K.; Rappa, F.; Cappello, F.; Camilleri, J.

    2016-01-01

    Portland cement used in the construction industry improves its properties when wet. Since most dental materials are used in a moist environment, Portland cement has been developed for use in dentistry. The first generation material is mineral trioxide aggregate (MTA), used in surgical procedures, thus in contact with blood. The aim of this study was to compare the setting of MTA in vitro and in vivo in contact with blood by subcutaneous implantation in rats. The tissue reaction to the material was also investigated. ProRoot MTA (Dentsply) was implanted in the subcutaneous tissues of Sprague-Dawley rats in opposite flanks and left in situ for 3 months. Furthermore the material was also stored in physiological solution in vitro. At the end of the incubation time, tissue histology and material characterization were performed. Surface assessment showed the formation of calcium carbonate for both environments. The bismuth was evident in the tissues thus showing heavy element contamination of the animal specimen. The tissue histology showed a chronic inflammatory cell infiltrate associated with the MTA. MTA interacts with the host tissues and causes a chronic inflammatory reaction when implanted subcutaneously. Hydration in vivo proceeds similarly to the in vitro model with some differences particularly in the bismuth oxide leaching patterns. PMID:27683067

  12. Microstructure: Surface and cross-sectional studies of hydroxyapatite formation on the surface of white Portland cement paste in vitro

    Science.gov (United States)

    Chaipanich, Arnon; Torkittikul, Pincha

    2011-08-01

    The formation of hydroxyapatite was investigated at the surface and at the cross-section of white Portland cement paste samples before and after immersion in simulated body fluid. Scanning electron microscope images showed that hydroxyapatite were found at the surface of white Portland cement after immersion in simulated body fluid. Hydroxyapatite grains of mostly ≈1 μm size with some grain size of ≈2-3 μm were seen after 4 days immersion period. More estabilshed hydroxyapatite grain size of ≈3 μm grains were observed at longer period of immersion at 7 and 10 days. The cross-section of the samples was investigated using line scanning technique and was used to determine the hydroxyapatite layer. A strong spectrum of phosphorus is detected up to 6-8 μm depth for samples after 4, 7 and 10 days immersion in simulated body fluid when compared to weak spectrum detected before immersion. The increase in the phosphorus spectrum corresponds to the hydroxyapatite formation on the surface of the samples after the samples were placed in simulated body fluid.

  13. Avaliação da permeabilidade de filtros de aerossóis para altas temperaturas, preparados a partir da técnica de adição de espuma aquosa em suspensão cerâmica Permeability characterization of hot aerosol filters prepared with foaming of ceramic suspensions

    Directory of Open Access Journals (Sweden)

    M. D. M. Innocentini

    2009-12-01

    Full Text Available Este trabalho é parte de um projeto de desenvolvimento de filtros cerâmicos para a remoção de material particulado disperso em correntes gasosas em temperaturas elevadas. Os filtros cerâmicos utilizados para esta finalidade devem apresentar elevada porosidade aliada a uma distribuição homogênea de poros interconectados, resultando em estrutura permeável e com boa resistência mecânica e eficiência de coleta. Uma rota de processamento recentemente desenvolvida é utilizada para o processamento das peças, já que permite a obtenção de todas as características requeridas para uma filtração eficiente. Nesta técnica, os materiais porosos são processados a partir da incorporação de espumas aquosas em uma suspensão cerâmica de alumina e consolidados a partir da adição de cimento aluminoso. Comparado com outras rotas de processamento, este processo é mais atrativo, pois permite a fabricação de peças com geometrias complexas, economicamente viáveis e sem utilização de aditivos tóxicos. O objetivo deste trabalho foi otimizar a composição cerâmica de modo a atender aos requisitos de permeabilidade do filtro, tendo como base sua operação econômica em temperaturas elevadas em processos como incineração de resíduos, produção de cimento ou queima de biomassa em caldeiras em plantas químicas.This work is part of a project to develop ceramic filters to treat flue gases from cement plants, biomass boilers and waste incinerators. Ceramic filters used for these purposes must present high porosity, homogeneous porous distribution (interconnected to result in bodies with high mechanical strength, permeability and collection efficiency for fine particles. A method recently developed has been used for the filters processing. In this new processing route, the porous samples were prepared through the incorporation of aqueous foams into alumina-based suspensions. Compared to other techniques, this process seems to be an

  14. Otimização da permeabilidade de filtros de aerossóis para altas temperaturas preparados a partir da técnica de adição de espuma aquosa em suspensão cerâmica Permeability optimization of hot aerosol filters prepared from foaming of ceramic suspensions

    Directory of Open Access Journals (Sweden)

    M. D. M. Innocentini

    2009-03-01

    Full Text Available Este trabalho é parte de um projeto de desenvolvimento de filtros cerâmicos para a remoção de material particulado disperso em correntes gasosas em temperaturas elevadas. Os filtros cerâmicos utilizados para esta finalidade devem apresentar elevada porosidade aliada a uma distribuição homogênea de poros interconectados, resultando em estrutura permeável e com boa resistência mecânica e eficiência de coleta. Uma rota de processamento recentemente desenvolvida é utilizada para o processamento das peças, já que permite a obtenção de todas as características requeridas para uma filtração eficiente. Nesta técnica, os materiais porosos são processados a partir da incorporação de espumas aquosas em uma suspensão cerâmica de alumina e consolidados a partir da adição de cimento aluminoso. Comparado com outras rotas de processamento, este processo é mais atrativo, pois permite a fabricação de peças com geometrias complexas, economicamente viáveis e sem utilização de aditivos tóxicos. O objetivo deste trabalho foi otimizar a composição cerâmica de modo a atender aos requisitos de permeabilidade do filtro, tendo como base sua operação econômica em temperaturas elevadas em processos como incineração de resíduos, produção de cimento ou queima de biomassa em caldeiras em plantas químicas.This work is part of a Brazilian project to develop ceramic filters to treat flue gases from cement plants, biomass boilers and waste incinerators. Ceramic filters used for these purposes must present high porosity, homogeneous porous distribution (interconnected to result in bodies with high mechanical strength, permeability and collection efficiency for fine particles. A method recently developed has been used for the filters processing. In this new processing route, the porous samples were prepared through the incorporation of aqueous foams into alumina-based suspensions. Compared to other techniques, this process seems to be

  15. Manufacturing of mortars and concretes non-traditionals, by Portland cement, metakaoline and gypsum (15.05%

    Directory of Open Access Journals (Sweden)

    Talero, R.

    1999-12-01

    Full Text Available In a thorough previous research (1, it appeared that creation, evolution and development of the values of compressive mechanical strength (CS and flexural strength (FS, measured in specimens 1x1x6cm of mortar type ASTM C 452-68 (2, manufactured by ordinary Portland cement P-1 (14.11% C3A or PY-6 (0.00% C3A, metakaolin and gypsum (CaSO4∙2H2O -or ternary cements, CT-, were similar to the ones commonly developed in mortars and concretes of OPC. This paper sets up the experimental results obtained from non-traditional mortars and concretes prepared with such ternary cements -TC-, being the portland cement/metakaolin mass ratio, as follows: 80/20, 70/30 and 60/40. Finally, the behaviour of these cements against gypsum attack, has been also determined, using the following parameters: increase in length (ΔL%, compressive, CS, and flexural, FS, strengths, and ultrasound energy, UE. Experimental results obtained from these non-traditional mortars and concretes, show an increase in length (ΔL, in CS and FS, and in UE values, when there is addition of metakaolin.

    En una exhaustiva investigación anterior (1, se pudo comprobar que la creación, evolución y desarrollo de los valores de resistencias mecánicas a compresión, RMC, y flexotracción, RMF, proporcionados por probetas de 1x1x6 cm, de mortero 1:2,75, selenitoso tipo ASTM C 452-68 (2 -que habían sido preparadas con arena de Ottawa, cemento portland, P-1 (14,11% C3A o PY- 6 (0,00% C3A, metacaolín y yeso (CaSO4∙2H2O-, fue semejante a la que, comúnmente, desarrollan los morteros y hormigones tradicionales de cemento portland. En el presente trabajo se exponen los resultados experimentales obtenidos de morteros y hormigones no tradicionales, preparados con dichos cementos ternarios, CT, siendo las proporciones porcentuales en masa ensayadas, cemento portland/metacaolín, las siguientes: 80/20, 70

  16. Imaging a fossil oolitic system with GPR, insights into the exposures of the Isle of Portland (UK)

    Science.gov (United States)

    Moreau, Julien; Hansen, Trine L.; Nielsen, Lars

    2015-04-01

    The Isle of Portland shows exposure of uppermost Jurassic oolitic carbonate all along its coast. The stone of Portland properties are famous as standards for concrete composition, as building material but also for sculpture. As a consequence, the Isle has been quarried intensively for hundreds of years. The regional exposure quality is very high with a potential 3D control. The site has seen generations of geologist trainees coming for field work. The Wessex Basin where the Isle is sitting contains an active petroleum system and the geologists visiting/training there use the carbonates of Portland as an analogue to equivalent Middle-East oil and gas reservoir. Surprisingly, although the site has a tremendous potential to understand the 3D architecture and the sedimentary dynamic of an oolitic system, only punctual observations of logs (1D), sometimes correlated have been published. Several studies place a shore line between the Isle and the continent striking NEE-SWW and facing towards the Channel. Facies changes are attributed to rapid sea-level variations and Walter's Law. We have collected an extensive GPR survey of the same stratigraphic interval (The Portland Freestone). With a total of 99 GPR profiles, we have produced grids on top of most of the coastal cliffs and quarry faces. We have encountered 3 main architectures: 2-m-high bars with steep clinoforms, 10s of metres-wide channels plugged with a variety of organisms and stacked aggrading bundles of multidirectional dunesets. Our dataset does not illustrate any major unconformity which could be attributed to a sharp sea-level drop. We have interpreted our sedimentary architecture to be the result of various hydrodynamic conditions associated with a mix of wave and tide influences. The Isle shows an island barrier complex which progrades into the basin but also expands laterally filling up the available space and cannibalising itself. More proximal facies are effectively observed in the north of the island

  17. Reference Gene Selection in the Desert Plant <em>Eremosparton songoricuem>m>

    Directory of Open Access Journals (Sweden)

    Dao-Yuan Zhang

    2012-06-01

    Full Text Available <em>Eremosparton songoricum em>(Litv. Vass. (<em>E. songoricumem> is a rare and extremely drought-tolerant desert plant that holds promise as a model organism for the identification of genes associated with water deficit stress. Here, we cloned and evaluated the expression of eight candidate reference genes using quantitative real-time reverse transcriptase polymerase chain reactions. The expression of these candidate reference genes was analyzed in a diverse set of 20 samples including various <em>E. songoricumem> plant tissues exposed to multiple environmental stresses. GeNorm analysis indicated that expression stability varied between the reference genes in the different experimental conditions, but the two most stable reference genes were sufficient for normalization in most conditions.<em> EsEFem> and <em>Esα-TUB> were sufficient for various stress conditions, <em>EsEF> and <em>EsACT> were suitable for samples of differing germination stages, and <em>EsGAPDH>and <em>Es>UBQ em>were most stable across multiple adult tissue samples. The <em>Es18Sem> gene was unsuitable as a reference gene in our analysis. In addition, the expression level of the drought-stress related transcription factor <em>EsDREB2em>> em>verified the utility of<em> E. songoricumem> reference genes and indicated that no single gene was adequate for normalization on its own. This is the first systematic report on the selection of reference genes in <em>E. songoricumem>, and these data will facilitate future work on gene expression in this species.

  18. Participação do colmo principal e dos afilhos na produtividade do arroz irrigado, em função da densidade de semeadura

    Directory of Open Access Journals (Sweden)

    Eduardo do Valle Lima

    2010-01-01

    Full Text Available Entre as práticas culturais a serem consideradas na implantação da cultura do arroz destaca-se a densidade de semeadura, que deve estabelecer, em grande parte, a participação do colmo principal e dos afilhos nos componentes da produção, possibilitando a obtenção da máxima produtividade. O trabalho teve como objetivo avaliar a participação do colmo principal e dos afilhos na produtividade de grãos de arroz, cv. IAC 102, no sistema irrigado por inundação, em função da densidade de semeadura. O experimento foi desenvolvido sob túnel plástico, em Botucatu (SP, em caixas d'água de cimento amianto de 500 L, contendo Neossolo Flúvico Ta Eutrófico, com profundidade de 30 cm. O delineamento experimental foi o inteiramente casualizado, com quatro repetições. As densidades de semeadura foram: 100, 200, 300, 400, 500 e 600 sementes viáveis por m², em 4 linhas de 1 m por caixa, espaçadas com 20 cm. A elevação da densidade de semeadura diminui o afilhamento e proporciona a maior participação dos colmos principais, porém, não resultando em incremento de produtividade, devido à plasticidade das plantas de arroz, que proporciona o ajustamento dos componentes da produção.

  19. High-volume natural volcanic pozzolan and limestone powder as partial replacements for portland cement in self-compacting and sustainable concrete

    KAUST Repository

    Celik, Kemal

    2014-01-01

    A laboratory study demonstrates that high volume, 45% by mass replacement of portland cement (OPC) with 30% finely-ground basaltic ash from Saudi Arabia (NP) and 15% limestone powder (LS) produces concrete with good workability, high 28-day compressive strength (39 MPa), excellent one year strength (57 MPa), and very high resistance to chloride penetration. Conventional OPC is produced by intergrinding 95% portland clinker and 5% gypsum, and its clinker factor (CF) thus equals 0.95. With 30% NP and 15% LS portland clinker replacement, the CF of the blended ternary PC equals 0.52 so that 48% CO2 emissions could be avoided, while enhancing strength development and durability in the resulting self-compacting concrete (SCC). Petrographic and scanning electron microscopy (SEM) investigations of the crushed NP and finely-ground NP in the concretes provide new insights into the heterogeneous fine-scale cementitious hydration products associated with basaltic ash-portland cement reactions. © 2013 Published by Elsevier Ltd.

  20. Fontes e níveis de proteína bruta em dietas para alevinos de pacu (Piaractus mesopotamicus

    Directory of Open Access Journals (Sweden)

    Fernandes João Batista Kochenborger

    2000-01-01

    Full Text Available Foi conduzido um experimento, com 100 dias duração, utilizando-se 288 alevinos de pacu, distribuídos em 36 caixas de cimento amianto com volume de 100 litros, para avaliar a substituição da farinha de peixe por farelo de soja e os níveis protéicos nas dietas. Durante o período experimental, a temperatura média da água permaneceu em 28ºC e os demais parâmetros limnológicos (oxigênio dissolvido, pH, alcalinidade e condutividade apresentaram-se dentro dos níveis adequados para o desenvolvimento desta espécie. O delineamento experimental foi de blocos casualizados, em que foram avaliados nove tratamentos em esquema fatorial 3 x 3, três níveis de proteína bruta (22, 26 e 30% e três níveis de substituição da farinha de peixe pelo farelo de soja (0, 50 e 100%. O nível de 26% de proteína bruta foi mais adequado. A farinha de peixe pode ser substituída parcial ou totalmente pelo farelo de soja, sem influir no ganho de peso, na conversão alimentar, na taxa de crescimento específico e na taxa de eficiência protéica dos alevinos. A substituição das fontes protéicas também não influenciou a composição corporal dos peixes, a eficiência de retenção de nitrogênio, o nitrogênio corporal, a gordura corporal e o nitrogênio e a gordura no ganho de peso.

  1. A Histologic Evaluation on Tissue Reaction to Three Implanted Materials (MTA, Root MTA and Portland Cement Type I in the Mandible of Cats

    Directory of Open Access Journals (Sweden)

    F. Sasani

    2004-09-01

    Full Text Available Statement of Problem: Nowadays Mineral Trioxide aggregate (MTA is widely used for root end fillings, pulp capping, perforation repair and other endodontic treatments.Investigations have shown similar physical and chemical properties for Portland cement and Root MTA with those described for MTA.Purpose: The aim of this in vitro study was to evaluate the tissue reaction to implanted MTA, Portland cement and Root MTA in the mandible of cats.Materials and Methods: Under asepsis condition and general anesthesia, a mucoperiosteal flap, following the application of local anesthesia, was elevated to expose mandibular symphysis. Two small holes in both sides of mandible were drilled. MTA, Portland cement and Root MTA were mixed according to the manufacturers, recommendation and placed in bony cavities. In positive control group, the test material was Zinc oxide powder plus tricresoformalin. In negative control group, the bony cavities were left untreated. After 3,6 and 12 weeks, the animals were sacrificed and the mandibular sections were prepared for histologic examination under light microscope. The presence and thickness of inflammation, presence of fibrosis capsule, the severity of fibrosis and bone formation were investigated. The data were submitted to Exact Fisher test, chi square test and Kruskal-Wallis test for statistical analysis.Results: No statistically significant differences were found in the degree of inflammation,presence of fibrotic capsule, severity of fibrosis and inflammation thickness between Root MTA, Portland cement and MTA (P>0.05. There was no statistical difference in boneformation between MTA and Portland cement (P>0.05. However, bone formation was not found in any of the Root MTA specimens and the observed tissue was exclusively of fibrosis type.Conclusion: The physical and histological results observed with MTA are similar to those of Root MTA and Portland cement. Additionally, all of these three materials are biocompatible

  2. Characterization of high-calcium fly ash and its influence on ettringite formation in portland cement pastes

    Science.gov (United States)

    Tishmack, Jody Kathleen

    High-calcium Class C fly ashes derived from Powder River Basin coal are currently used as supplementary cementing materials in portland cement concrete. These fly ashes tend to contain significant amounts of sulfur, calcium, and aluminum, thus they are potential sources of ettringite. Characterization of six high-calcium fly ashes originating from Powder River Basin coal have been carried out. The hydration products formed in pastes made from fly ash and water were investigated. The principal phases produced at room temperature were ettringite, monosulfate, and stratlingite. The relative amounts formed varied with the specific fly ash. Removal of the soluble crystalline sulfur bearing minerals indicated that approximately a third of the sulfur is located in the fly ash glass. Pore solution analyses indicated that sulfur concentrations increased at later ages. Three fly ashes were selected for further study based on their ability to form ettringite. Portland cement-fly ash pastes made with the selected fly ashes were investigated to evaluate ettringite and monosulfate formation. Each of the fly ashes were mixed with four different types of portland cements (Type I, I/II, II, and III) as well as three different Type I cements exhibiting a range of C3A and sulfate contents. The pastes had 25% or 35% fly ash by total weight of solids and a water:cement-fly ash ratio of 0.45. The samples were placed in a curing room (R.H. = 100, 23°C) and were then analyzed at various ages by x-ray diffraction (XRD) and differential scanning calorimetry (DSC) to determine the principal hydration products. The hydration products identified by XRD were portlandite, ettringite (an AFt phase), monosulfate, and generally smaller amounts of hemicarboaluminate and monocarboaluminate (all AFm phases). Although the amount of ettringite formed varied with the individual cement, only a modest correlation with cement sulfate content and no correlation with cement C3A content was observed. DSC

  3. Corrosion rate of steel embedded in blended Portland and fluid catalytic cracking catalyst residue (FC3R cement mortars

    Directory of Open Access Journals (Sweden)

    Payá, J.

    2008-12-01

    Full Text Available This paper reports on a study of the corrosion levels in steel bars embedded in mortars made with a blend of Portland cement and (0-20% spent fluid catalytic cracking catalyst residue (FC3R, with a variable (0.3-0.7 water/binder (w/b ratio. The specimens were stored in the following conditions: relative humidity of 40, 80 or 100% and CO2 concentrations of 5 and 100%. The steel corrosion rate was measured with polarization resistance techniques. In the absence of aggressive agents, the steel was found to remain duly passivated in mortars with an FC3R content of up to 15% under all the conditions of relative humidity tested. The reinforcement corrosion level in mortars with a w/b ratio of 0.3 and 15% FC3R subjected to accelerated carbonation was similar to the level observed in the unblended Portland cement control mortar.En este trabajo se ha estudiado el nivel de corrosión de barras de acero embebidas en morteros de cemento Portland con relación agua/material cementante (a/mc variable (0,3-0,7, en los que parte del cemento (0-20% se sustituyó por catalizador de craqueo usado (FC3R. Las condiciones de conservación de las probetas elaboradas fueron las siguientes: distintas humedades relativas (40, 80 y 100% y dos concentraciones de CO2 (5 y 100%. La velocidad de corrosión de los aceros se midió mediante la técnica de resistencia de polarización. Se ha podido determinar que, bajo las distintas condiciones de humedad relativa y ausencia de agresivo, los aceros se mantuvieron correctamente pasivados en los morteros con contenidos de FC3R de hasta el 15%. El nivel de corrosión que presenta el refuerzo embebidos en morteros con sustitución de un 15% de cemento por FC3R y relación a/mc 0,3, al ser sometidos a un proceso de carbonatación acelerada, era muy similar al mostrado por el mortero patrón, sin FC3R.

  4. Effect of mixes made of coal bottom ash and fly ash on the mechanical strength and porosity of Portland cement

    Directory of Open Access Journals (Sweden)

    Argiz, C.

    2013-03-01

    Full Text Available New additions to the cement are needed to achieve a more sustainable and durable construction material. Within this context, bottom ashes can be used as a main constituent of Portland cements when it is mixed in an optimized proportion with fly ashes. The mechanical characteristics of standarized mortars made of mixes of pulverized coal combustion bottom and fly ashes are studied. The mortars were made of ordinary Portland cement (CEM I 42.5 N and mixes of bottom ashes with fly ashes in similar proportions to those of CEM II/A-V, CEM II/B-V and CEM IV/A (V. Summing up, it can be said that the utilization of bottom ashes mixed with fly ashes in replacement levels from 0% to 100% do not affect significantively on the mechanical caracteristics of the mortars considered in the present study which had an addition maximum content of 35%.

    La utilización de nuevas adiciones en el cemento es necesaria con el fin de obtener un material más sostenible y durable. En este sentido, las cenizas de fondo o cenicero de las centrales termoeléctricas de carbón se podrían reciclar siendo empleadas como un componente principal de los cementos Portland. Se han estudiado las propiedades mecánicas de unos morteros normalizados elaborados con mezclas de cenizas volantes con cenizas de fondo fabricados con unos porcentajes similares a los correspondientes de los CEM II/A-V, CEM II/B-V y CEM IV/A (V. En conclusión, la utilización de mezclas de cenizas de fondo o cenicero con cenizas volantes sustituyendo a éstas últimas entre el 0% y el 100%, no influye significativamente en el comportamiento mecánico de los morteros estudiados en los que el contenido máximo de adición ha sido del 35%, si bien afecta a determinados aspectos microestructurales, como la cantidad y distribución de poros capilares.

  5. Effect of sewage sludge ash (SSA on the mechanical performance and corrosion levels of reinforced Portland cement mortars

    Directory of Open Access Journals (Sweden)

    Andión, L. G.ª

    2006-06-01

    Full Text Available The article describes a study conducted to determinecorrosion in reinforcement embedded in Portland cement(PC mortars with different percentages of sewage sludgeash (SSA admixtures. The polarization resistancetechnique was used to determine the steel corrosion rate(Icorr in the test specimens. The samples were subjectedto different environmental conditions and aggressiveagents: 100% relative humidity (RH, accelerated carbonationat 70% RH and seawater immersion. Portlandcement was partially substituted for SSA in the mixes atrates of 0, 10, 20, 30 and 60% (by mass to make thedifferent mortars. The results show that where cementwas replaced by SSA at rates of up to 10% by mass,mortar corrosion performance was comparable to thebehaviour observed in SSA-free mortars (control mortar:0% SSA. Data for higher rates are also shown. From themechanical standpoint, SSA exhibited moderate pozzolanicactivity and the best performance when SSA wasadded at a rate of 10% to mixes with a water/(binder:PC + SSA (w/b ratio of 0.5.Se ha estudiado el nivel de corrosion que presentan lasarmaduras embebidas en morteros fabricados con cementoPortland (CP con diferentes porcentajes de sustitucion deceniza de lodo de depuradora (CLD. Se ha utilizado la tecnicade la Resistencia a la Polarizacion para determinar lavelocidad de corrosion del acero embebido en las muestrasestudiadas. Las muestras se han sometido a diferentes condicionesambientales y agentes agresivos: 100% de humedadrelativa (HR, carbonatacion acelerada al 70% HR einmersion en agua de mar. Para la fabricacion de los distintosmorteros, el cemento Portland ha sido parcialmente sustituidopor CLD en los siguientes porcentajes en masa: 0,10, 20, 30 y 60%. Los resultados muestran que sustitucionesde cemento por CLD de hasta el 10% en masa no alteranel comportamiento frente a la corrosion de los morterosal compararlos con los morteros libres de CLD (morteroscontrol: 0% de sustitucion de cemento por CLD. Se

  6. Synthesis, Crystal Structure and Luminescent Property of Cd (II Complex with <em>N-Benzenesulphonyl-L>-leucine

    Directory of Open Access Journals (Sweden)

    Xishi Tai

    2012-09-01

    Full Text Available A new trinuclear Cd (II complex [Cd3(L6(2,2-bipyridine3] [L =<em> Nem>-phenylsulfonyl-L>-leucinato] has been synthesized and characterized by elemental analysis, IR and X-ray single crystal diffraction analysis. The results show that the complex belongs to the orthorhombic, space group<em> Pem>212121 with<em> aem> = 16.877(3 Å, <em>b> em>= 22.875(5 Å, <em>c em>= 29.495(6 Å, <em>α> em>= <emem>= <emem>= 90°, <em>V> em>= 11387(4 Å3, <em>Z> em>= 4, <em>Dc>= 1.416 μg·m−3, <emem>= 0.737 mm−1, <em>F> em>(000 = 4992, and final <em>R>1 = 0.0390, <em>ωR>2 = 0.0989. The complex comprises two seven-coordinated Cd (II atoms, with a N2O5 distorted pengonal bipyramidal coordination environment and a six-coordinated Cd (II atom, with a N2O4 distorted octahedral coordination environment. The molecules form one dimensional chain structure by the interaction of bridged carboxylato groups, hydrogen bonds and p-p interaction of 2,2-bipyridine. The luminescent properties of the Cd (II complex and <em>N-Benzenesulphonyl-L>-leucine in solid and in CH3OH solution also have been investigated.

  7. Characterization and utilization of cement kiln dusts (CKDs) as partial replacements of Portland cement

    Science.gov (United States)

    Khanna, Om Shervan

    The characteristics of cement kiln dusts (CKDs) and their effects as partial replacement of Portland Cement (PC) were studied in this research program. The cement industry is currently under pressure to reduce greenhouse gas (GHG) emissions and solid by-products in the form of CKDs. The use of CKDs in concrete has the potential to substantially reduce the environmental impact of their disposal and create significant cost and energy savings to the cement industry. Studies have shown that CKDs can be used as a partial substitute of PC in a range of 5--15%, by mass. Although the use of CKDs is promising, there is very little understanding of their effects in CKD-PC blends. Previous studies provide variable and often conflicting results. The reasons for the inconsistent results are not obvious due to a lack of material characterization data. The characteristics of a CKD must be well-defined in order to understand its potential impact in concrete. The materials used in this study were two different types of PC (normal and moderate sulfate resistant) and seven CKDs. The CKDs used in this study were selected to provide a representation of those available in North America from the three major types of cement manufacturing processes: wet, long-dry, and preheater/precalciner. The CKDs have a wide range of chemical and physical composition based on different raw material sources and technologies. Two fillers (limestone powder and quartz powder) were also used to compare their effects to that of CKDs at an equivalent replacement of PC. The first objective of this study was to conduct a comprehensive composition analysis of CKDs and compare their characteristics to PC. CKDs are unique materials that must be analyzed differently from PC for accurate chemical and physical analysis. The present study identifies the chemical and physical analytical methods that should be used for CKDs. The study also introduced a method to quantify the relative abundance of the different

  8. Evaluation of red mud as pozzolanic material in replacement of cement for production of mortars; Avaliacao da lama vermelha como material pozolanico em substituicao ao cimento para producao de argamassas

    Energy Technology Data Exchange (ETDEWEB)

    Manfroi, E.P.; Cheriaf, M.; Rocha, J.C., E-mail: elizmanfroi@yahoo.com.b, E-mail: malik@valores.ufsc.b [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. de Engenharia Civil

    2010-07-01

    Red mud is a by-product of the alkaline extraction of aluminum from the bauxite and represents a renewed environmental problem due the significant annual throughput by the plants. In the present work, the pozzolanic properties of Brazilian red mud fired at 600, 700, 800 and 900 deg C were investigated by monitoring lime consumption using DTA analysis and Brazilian standard methodology NBR 5772 (1992). Products and kinetics of hydration were determined in cement pastes produced with 5 and 15% red mud using x-ray diffraction and DTA analysis. Compressive strength and capillary absorption tests were realized on mortars constituted by 5, 10 and 15% red mud in replacement of cement. When calcined at 600 deg C, the red mud develops good pozzolanic properties, and the compressive strength of mortars produced with this waste meet values in accordance with regulatory standard. These results shown than red mud can be used, in partial replacement of cement, as new construction material to produce sustainable mortars with low environmental impact. (author)

  9. Penetration of natural gas in industrial processes for direct burning: the case of ceramics, cement and glass industries; Penetracao do gas natural em processos industriais de queima direta: caso das industrias ceramica, cimento e vidro

    Energy Technology Data Exchange (ETDEWEB)

    Berni, Mauro Donizeti; Leite, Alvaro A. Furtado [Universidade Estadual de Campinas (UNICAMP), SP (Brazil); Dorileo, Ivo Leandro [Universidade Federal do Mato Grosso (NIEPE/UFMT), Cuiaba, MT (Brazil). Nucleo Interdisciplinar de Estudos em Planejamento Energetico; Bajay, Sergio Valdir [Universidade estadual de Campinas (FEM/UNICAMP), SP (Brazil). Fac. de Engenharia Mecanica. Dept. de Energia], e-mail: bajay@fem.unicamp.com.br

    2008-07-01

    Industrial sector can use the natural gas (NG) as raw material, as fuel and in co-generation. The NG as fuel is used, predominantly, to produce heat in the Brazilian industries. That rate, both main forms of industrial use of the NG are its direct burning in kilns - when the direct contact is had with the product - and the supply of process heat through boilers, for instance. Direct burning is used in the ceramic, cement and glass industries. This work discuss the penetration opportunity of the NG in the direct burning regarding the fuel oil and other energy that it can substitute, the environmental effects and the co-generation possibilities in each one of the analyzed industrial blanches in this work. (author)

  10. Evolución de la Porosidad de Pastas de Cemento Portland por la Incorporación de una Puzolana Natural Evolution of Porosity in Portland Cement Pastes by addition of Natural Pozzolan

    Directory of Open Access Journals (Sweden)

    J.L. Fernández

    2004-01-01

    Full Text Available Se ha determinado la evolución que se produce en la porosidad de las pastas elaboradas con cemento Portland para uso general (CPN IRAM 50000, al incorporarle una puzolana natural de la región, en distintas proporciones y en función del tiempo de curado. El ensayo de porosidad se realiza según Norma API-RP-40, basada en la ley de Boyle, por la cual se determina el volumen de los vacíos de las pastas. Este se determina por diferencia entre el volumen total del gas a una presión P1 de 6.9.10(5 Pa y el volumen calibrado de una celda donde se encuentra la muestra a presión atmosférica P0. Posteriormente, se ingresa en la curva de calibración del porosímetro y se obtienen los volúmenes de sólido de las mezclas. Como conclusión se demuestra que la porosidad de las pastas disminuye con el aumento de la cantidad de cemento reemplazado y del tiempo de curadoA determination was made of the evolution of porosity in Portland cement pastes for general usage (CPN IRAM 50000 by incorporating different proportions of natural pozzolan from the region, and as a function of curing time. The API-RP-40 norm based on Boyle´s law was used to measure the porosity, determining the paste effective void volume. This is done by calculating the difference between the total gas space at a pressure P1 of 6,9 .10(5 Pa and the calibrated volume of the cell at atmospheric pressure P0. Then the paste volume was obtained by porosimeter calibration curves. In conclusion, this study demonstrates that the porosity of pastes decreases as a function of the amount of cement replaced and time of cure

  11. Adsorption of cefixime from aqueous solutions using modified hardened paste of Portland cement by perlite; optimization by Taguchi method.

    Science.gov (United States)

    Rasoulifard, Mohammad Hossein; Khanmohammadi, Soghra; Heidari, Azam

    In the present study, we have used a simple and cost-effective removal technique by a commercially available Fe-Al-SiO2 containing complex material (hardened paste of Portland cement (HPPC)). The adsorbing performance of HPPC and modified HPPC with perlite for removal of cefixime from aqueous solutions was investigated comparatively by using batch adsorption studies. HPPC has been selected because of the main advantages such as high efficiency, simple separation of sludge, low-cost and abundant availability. A Taguchi orthogonal array experimental design with an OA16 (4(5)) matrix was employed to optimize the affecting factors of adsorbate concentration, adsorbent dosage, type of adsorbent, contact time and pH. On the basis of equilibrium adsorption data, Langmuir, Freundlich and Temkin adsorption isotherm models were also confirmed. The results showed that HPPC and modified HPPC were both efficient adsorbents for cefixime removal.

  12. Characterization using thermomechanical and differential thermal analysis of the sinterization of Portland clinker doped with CaF{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Dominguez, O., E-mail: nanoquimica@yahoo.com [Fac. de Quimica-UASLP, Av. Dr. Salvador Nava 6, CP 78210, San Luis Potosi, SLP (Mexico); Torres-Castillo, A. [Fac. de Quimica-UASLP, Av. Dr. Salvador Nava 6, CP 78210, San Luis Potosi, SLP (Mexico); Flores-Velez, L.M. [Instituto de Metalurgia-UASLP, Sierra Leona 550, CP 78210, San Luis Potosi, SLP (Mexico); Torres, R. [Mexichem Fluor S.A., Eje 106 s/n CP 78395, San Luis Potosi, SLP (Mexico)

    2010-04-15

    In this work, the sintering process of Portland cement was studied by combining thermomechanical analysis (TMA) and differential thermal analysis (DTA), together with X-ray diffraction (XRD) and scanning electron microscopy (SEM). Thermal analysis results employing both techniques indicted that phase transformations appeared at lower temperatures when CaF{sub 2} was incorporated in the raw materials. Besides, it was observed at high temperature that in some phase transformations TMA conducts to better resolution compared with the DTA measurements. Furthermore, mechanical properties and X-ray diffraction patterns corroborate the TMA and DTA results, corroborating that the final amount of alite (Ca{sub 3}SiO{sub 5}) is higher when a certain amount of CaF{sub 2} was present during the clinkerization process.

  13. The radiation stability of ground granulated blast furnace slag/ordinary Portland cement grouts containing organic admixtures

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, J.D.; Fairhall, G.A. [British Nuclear Fuels, Sellafield (United Kingdom)

    1993-12-31

    At the British Nuclear Fuels (BNFL) Sellafield reprocessing plant in the United Kingdom, cement grouts based on ground granulated blast-furnace slag (BFS) and ordinary Portland cement (OPC) are used extensively for immobilizing radioactive wastes. These grouts have excluded organic admixtures in order to reduce process complexity and uncertainties, regarding the performance of organic admixtures with BFS/OPC grouts, particularly under irradiation. This study has investigated the effects of sulfonated melamine formaldehyde and naphthalene condensates on grout properties. The results show grout settlement and strengths increase on addition of additives, with the additives remaining largely in the pore solution. Under irradiation the additives breakdown liberating hydrogen and carbon dioxide. Strength and product dimensions are unaffected by irradiation.

  14. Demonstration Assessment of Light-Emitting Diode (LED) Retrofit Lamps at the Lobby of the Bonneville Power Administration, Portland, OR

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Naomi

    2011-07-01

    This report describes the process and results of a demonstration of solid-state lighting (SSL) technology in the lobby of the Bonneville Power Administration (BPA) headquarters building in Portland, Oregon. The project involved a simple retrofit of 32 track lights used to illuminate historical black-and-white photos and printed color posters from the 1930s and 1940s. BPA is a federal power marketing agency in the Northwestern United States, and selected this prominent location to demonstrate energy efficient light-emitting diode (LED) retrofit options that not only can reduce the electric bill for their customers but also provide attractive alternatives to conventional products, in this case accent lighting for BPA's historical artwork.

  15. Evaluation of physical stability and leachability of Portland pozzolona cement (PPC) solidified chemical sludge generated from textile wastewater treatment plants.

    Science.gov (United States)

    Patel, Hema; Pandey, Suneel

    2012-03-15

    The chemical sludge generated from the treatment of textile dyeing wastewater is a hazardous waste as per Indian Hazardous Waste Management rules. In this paper, stabilization/solidification of chemical sludge was carried out to explore its reuse potential in the construction materials. Portland pozzolona cement (PPC) was selected as the binder system which is commercially available cement with 10-25% fly ash interground in it. The stabilized/solidified blocks were evaluated in terms of unconfined compressive strength, block density and leaching of heavy metals. The compressive strength (3.62-33.62 MPa) and block density (1222.17-1688.72 kg/m3) values as well as the negligible leaching of heavy metals from the stabilized/solidified blocks indicate that there is a potential of its use for structural and non-structural applications.

  16. Evaluation of Compatibility between Beetle-Killed Lodgepole Pine (Pinus Contorta var. Latifolia Wood with Portland Cement

    Directory of Open Access Journals (Sweden)

    Ian D. Hartley

    2010-12-01

    Full Text Available The compatibility of wood from mountain pine beetle (Dendroctonus ponderosa killed lodgepole pine (Pinus contorta var. latifolia with Portland cement was investigated based on time-since-death as a quantitative estimator, and the presence of blue-stained sapwood, brown rot, or white rot as qualitative indicators. The exothermic behavior of cement hydration, maximum heat rate, time to reach this maximum, and total heat released within a 3.5–24 h interval were used for defining a new wood-cement compatibility index (CX. CX was developed and accounted for large discrepancies in assessing wood-cement compatibility compared to the previous methods. Using CX, no significant differences were found between fresh or beetle-killed wood with respect to the suitability for cement; except for the white rot samples which reached or exceeded the levels of incompatibility. An outstanding physicochemical behavior was also found for blue-stained sapwood and cement, producing significantly higher compatibility indices.

  17. Marine durability of 15 year old concrete specimens made with ordinary portland, slag, and fly ash cements

    Energy Technology Data Exchange (ETDEWEB)

    Mohammed, T.U.; Yamaji, T.; Hamada, H. [Port and Harbor Research Inst., Ministry of Land, Infrastructure and Transport (Japan); Aoyama, T. [PS Corp. (Japan)

    2001-07-01

    A study was conducted in which the marine durability of ordinary portland cement, slag and fly ash cement was examined using 15 year old plain and reinforced concrete cylindrical specimens. In addition, the performance of these cements was also examined in another study for pre-cracked reinforced concrete prism samples. The process of manufacturing cement emits huge amounts of carbon dioxide into the global atmosphere. Replacing a portion of the cement with by-products from the steel industry and thermal power plants (which are both huge emitters of carbon dioxide) can lower carbon dioxide emissions and also solve the disposal issue of slag and fly ash while increasing the long-term durability of concrete structures. In this study, concrete cylindrical specimens were made of ordinary portland cement, slag and fly ash cements. Water-to-cement ratios were 0.45 and 0.55 and the compressive strength of the concrete, corrosion of the steel bars, and chloride-ion concentrations in the concrete were evaluated. It was shown that, with the exception of fly ash cements, the compressive strength of most cements increased after 15 years of exposure compared to its 28 day strength. Type C slag cement demonstrated the best performance against chloride-ion at the surface of concrete made with slag and fly ash. Voids in the steel-concrete interface make it possible for corrosion pits to develop. The use of seawater as mixing water results in earlier strength development at 28 days and does not cause to the strength of the concrete to regress after 15-years of exposure, but it causes more corrosion of steel bars at a lower cover depth. Corrosion of steel bars is not an issue at deeper cover depths. 15 refs., 18 tabs., 8 figs.

  18. Resistência à remoção por tração de coroas totais metálicas cimentadas em dentes com e sem reconstrução coronária Tensile strength of metal crowns cemented on dental and buildup surfaces

    Directory of Open Access Journals (Sweden)

    Eduardo Batista FRANCO

    1999-12-01

    Full Text Available O objetivo deste estudo foi verificar a resistência à remoção por tração de coroas totais metálicas cimentadas com o cimento de ionômero de vidro Ketac-Cem (ESPE em dentes adequadamente preparados, com e sem o pré-tratamento dentinário com o ácido poliacrílico a 40%, assim como sobre dentes previamente reconstruídos com o cimento ionomérico Vitremer (3M. Para efeito de comparação, empregou-se o cimento de fosfato de zinco (SS White. Foram selecionados 50 dentes humanos (primeiros pré-molares superiores sendo os mesmos fixados em bases cilíndricas de resina acrílica poliestirênica e divididos em 5 grupos de 10 elementos cada. Após a cimentação, os espécimes foram termociclados nas temperaturas de 5ºC, 37ºC e 55ºC e posteriormente acoplados à máquina de ensaios universal (Kratos, para a realização dos testes de resistência à tração. Os resultados obtidos foram submetidos a ANOVA, observando-se diferença estatística significante ao nível de 5% entre as diferentes condições estudadas. Com relação aos dentes sem reconstrução, verificou-se um resultado superior para o cimento Ketac-Cem quando da utilização do ácido poliacrílico. Para os grupos reconstruídos com o Vitremer, não observou-se diferença estatística significante entre os dois agentes cimentantes. A reconstrução coronária não prejudicou a retentividade das coroas totais metálicas.The purpose of this study was to evaluate the tensile strength of metal crowns cemented with Ketac-Cem (ESPE glass ionomer cement, on teeth properly prepared with and without previous treatment of 40% polyacrylic acid, as well as on built-up teeth reconstructed with Vitremer (3M ionomer cement. For comparison purposes, zinc phosphate cement (SS White was also employed. Fifty upper pre-molar human teeth were selected, embedded in epoxy resin, and divided into 5 groups of 10 elements each. After cementing, the specimens were submitted to thermocycling at 5

  19. <em>α>-Glucosidase Inhibitory Constituents from <em>Acanthopanax senticosusem> Harm Leaves

    Directory of Open Access Journals (Sweden)

    Hai-Xue Kuang

    2012-05-01

    Full Text Available A new triterpene glycoside, 3-<em>O-[(α>-L-rhamnopyranosyl(1→2]-[<em>β>-D-glucuronopyranosyl-6-<em>O>-methyl ester]-olean-12-ene-28-olic acid (1 and a new indole alkaloid, 5-methoxy-2-oxoindolin-3-acetic acid methyl ester (5 were isolated from the leaves of <em>Acanthopanax senticosusem> Harms along with six known compounds. The structures of the new compounds were determined by means of 2D-NMR experiments and chemical methods. All the isolated compounds were evaluated for their glycosidase inhibition activities and compound 6 showed significant <em>α>-glucosidase inhibition activity.

  20. Reuse of a residue from petrochemical industry with portland cement Reutilización de un residuo de la industria petroquímica como adición al cemento portland

    Directory of Open Access Journals (Sweden)

    Janneth Torres Agredo

    2012-06-01

    Full Text Available In this article the possibility of using waste from the petrochemical industry,as partial replacement of Portland cement is studied, evaluating the presenceof contaminants in the waste and the encapsulation, once it is confined on the cement. This has been done, in order to find a use to this residue without cause damage to the environment. This residue, called spent fluid catalytic cracking catalyst (FCC, is mainly formed by a type Y zeolite, which is dispersing in an inorganic oxides matrix. The toxicity characteristic leaching proceeding was applied, in mortars adding with 20% of FCC as Portland cement replacement. The results showed that the residue does not represent a problem from the point of view of the leaching of elements, such as As, Pb, Zn, Cr, and La, which were below to the permissible limits. Additionally, the pozzolanic activity of FCC was evaluated according to ASTM C311, where the efficiency of the residue as pozzolanic addition is demonstrated. With the results the importance of reusing a residue of the petrochemical industry is emphasized, that decreases the amount of cement to be used and improves the mechanical resistance of the materials containing it.En el presente artículo se estudia la posibilidad de utilizar un residuo de la industria petroquímica, como sustitución parcial del cemento Portland, evaluando la presencia de elementos contaminantes en el residuo y su encapsulación, una vez se haya confinado con el cemento. Lo anterior, con el fin de determinar si su uso como material de construcción, puede o no causar un efecto negativo al medio ambiente. El residuo, denominado catalizador usado de craqueo catalítico (FCC, es un material que está compuesto por una zeolita tipo Y, dispersa en una matriz de óxidos inorgánicos. Se aplicó la técnica de TCLP (del inglés Toxicity Characteristic Leaching Procedure, en morteros adicionados con un 20%, de FCC con respecto a la cantidad de cemento. Los resultados

  1. Reposição de nutrientes durante três cultivos de alface em hidroponia

    Directory of Open Access Journals (Sweden)

    Backes Fernanda Alice A.L.

    2003-01-01

    Full Text Available O experimento foi realizado em estufa plástica na UFSM, de agosto a novembro/99. Avaliou-se cinco formas de reposição de nutrientes na solução nutritiva com base na condutividade elétrica (CE, no sistema 'NFT' (Nutrient Film Technique e duas cultivares de alface: Regina e Deisy, cultivadas em bancadas de sustentação formadas por telhas de fibro-cimento revestidas com tinta betuminosa Neutrolâ. Foram dispostas 14 plantas por canal para cada repetição e uma cultivar em cada três canais, totalizando 84 plantas por bancada de produção. Comparou-se a eficiência de métodos de reposição de nutrientes na produção de alface, assim como a utilização da mesma solução, com reposição de nutrientes, durante três cultivos consecutivos. O delineamento experimental foi de blocos casualizados, com três repetições, em esquema fatorial 5x2. Os resultados demonstraram que o desempenho das cultivares avaliadas não foi influenciado pelos métodos de reposição de nutrientes. A ausência de reposição de nutrientes na solução nutritiva, durante um cultivo, permitiu maior produtividade da cultura, não se recomendando a reposição quando o objetivo for renovar a solução ao final do cultivo. As formas de reposição de nutrientes na solução nutritiva, durante o primeiro e segundo cultivos, não alteraram a produtividade da cultura em relação à renovação completa da solução nutritiva ao final do cultivo hidropônico. Para a reutilização de solução nutritiva, recomenda-se a reposição de nutrientes sempre que a CE diminuir 50% da inicial, possibilitando a produção por pelo menos três cultivos.

  2. Three New Myrsinol Diterpenes from <em>Euphorbia proliferaem> and Their Neuroprotective Activities

    Directory of Open Access Journals (Sweden)

    Yuanqiang Guo

    2012-08-01

    Full Text Available Three new myrsinol diterpenes were isolated from the roots of<em> em>>Euphorbia proliferaem>. Their structures were elucidated as 2<em>α-O>-isobutyryl-3<em>β>,5<em>α>,7<em>β>,10,15<em>β-penta-O>-acetyl-14<em>α-O>-benzoyl-10,18-dihydromyrsinol (1, 2<em>α-O>-isobutyryl-3<em>β-O>-propion-yl-5<em>α>,7<em>β>,10,15<em>β-tetra-O>-acetyl-10,18-dihydromyrsinol (2, and 2<em>α>,14<em>α-di-O>-benzoyl-3<em>β>,5<em>α>,7<em>β>,10,15<em>β-penta-O>-acetyl-10,18-dihydromyrsinol (3 on the basis of spectroscopic data analyses (IR, ESI-MS, HR-ESI-MS, and 1D and 2D NMR. Their neuroprotective activities were evaluated and compounds 1 and 2 showed neuroprotective effects against MPP+-induced neuronal cell death in SH-SY5Y cells.

  3. Performance of portland limestone cements: Cements designed to be more sustainable that include up to 15% limestone addition

    Science.gov (United States)

    Barrett, Timothy J.

    In 2009, ASTM and AASHTO permitted the use of up to 5% interground limestone in ordinary portland cement (OPC) as a part of a change to ASTM C150/AASHTO M85. When this work was initiated a new proposal was being discussed that would enable up to 15% interground limestone cement to be considered in ASTM C595/AASHTO M234. This work served to provide rapid feedback to the state department of transportation and concrete industry for use in discussions regarding these specifications. Since the time this work was initiated, ASTM C595/AASHTO M234 was passed (2012c) and PLCs are now able to be specified, however they are still not widely used. The proposal for increasing the volume of limestone that would be permitted to be interground in cement is designed to enable more sustainable construction, which may significantly reduce the CO2 that is embodied in the built infrastructure while also extending the life of cement quarries. Research regarding the performance of cements with interground limestone has been conducted by the cement industry since these cements became widely used in Europe over three decades ago, however this work focuses on North American Portland Limestone Cements (PLCs) which are specifically designed to achieve similar performance as the OPCs they replace.This thesis presents a two-phase study in which the potential for application of cements containing limestone was assessed. The first phase of this study utilized a fundamental approach to determine whether cement with up to 15% of interground or blended limestone can be used as a direct substitute to ordinary portland cement. The second phase of the study assessed the concern of early age shrinkage and cracking potential when using PLCs, as these cements are typically ground finer than their OPC counterparts. For the first phase of the study, three commercially produced PLCs were obtained and compared to three commercially produced OPCs made from the same clinker. An additional cement was tested

  4. Aluminatos de cálcio e seu potencial para aplicação em endodontia e ortopedia

    Directory of Open Access Journals (Sweden)

    L. L. M. F. Pompeu

    2013-06-01

    Full Text Available Os materiais de maior uso em Endodontia como retro-obturador ou selador de defeitos na comunicação da raiz com o periodonto lateral (MTA, mineral trioxide aggregate e em Ortopedia, para fixar implantes e na remodelação óssea perdida (PMMA, polimetilmetacrilato, apresentam respectivamente, algumas propriedades limitantes como: longo tempo de presa e alta temperatura durante a polimerização. Tais limitações indicam a necessidade de alterações em suas composições bem como o desenvolvimento de materiais alternativos visando expandir suas aplicações. Neste contexto, um novo biomaterial a base de cimento de aluminato de cálcio (CAC tem sido estudado visando preservar as propriedades positivas e aplicações clínicas do MTA e PMMA superando algumas de suas desvantagens. Estudos recentes envolvendo o uso de CAC têm sido baseados em produtos comerciais compostos por uma mistura de fases. Melhorias neste sentido podem ser alcançadas pesquisando as rotas de síntese do CAC visando o adequado balanço entre as fases e o controle das impurezas que podem prejudicar a sua atuação em aplicações em áreas da saúde. A produção de fases de CAC isoladamente foi estudada anteriormente e neste trabalho é apresentada a sua caracterização quanto à temperatura de reação de hidratação; trabalhabilidade/tempo de presa e quanto a influência sobre pH, condutividade iônica e concentração de sólidos da água e diferentes soluções simuladoras de fluido corporal quando em contato com as fases. Os resultados apresentados indicaram as fases CaO.Al2O3 (CA e CaO.2Al2O3 (CA2 como as mais promissoras para as aplicações pretendidas.

  5. Determination of strontium and simultaneous determination of strontium oxide, magnesium oxide and calcium oxide content of Portland cement by derivative ratio spectrophotometry.

    Science.gov (United States)

    Idriss, K A; Sedaira, H; Ahmed, S S

    2009-04-15

    A derivative spectrophotometric method has been developed for the determination of strontium in Portland cement. The method is applied successfully for the simultaneous determination of SrO, MgO and CaO. It is based on the use of Alizarin Complexone (AC) as a complexing agent and measurement of the derivative ratio spectra of the analytes. Interferences of manganese(II) and zinc(II) were eliminated by precipitation. The validity of the method was examined by analyzing several Standard Reference Material (SRM) Portland cement samples. The strontium complex formed at pH 9.5 allows precise and accurate determination of strontium over the concentration range of 1.5-18 mg L(-1) of strontium. The MDL (at 95% confidence level) was found to be 25 ng mL(-1) for strontium in National Institute of Standards and Technology (NIST) cement samples using the proposed method.

  6. Utilización de ladrillos de adobe estabilizados con cemento portland al 6% y reforzados con fibra de coco, para muros de carga en Tampico

    Directory of Open Access Journals (Sweden)

    Olivares Santiago, Manuel

    2002-04-01

    Full Text Available In this article conclusions are presented about adobe bricks stabilized with 6% portland cement and reinforced with different percentages of coconut fibers. The author, has developed an experimental plan in laboratory and has built in situ several walls with different bricks, different joints and different orientations, to analyze the behaviour ofthe brick prototypes for the weather conditions in Tampico.En este artículo se presentan las conclusiones acerca del refuerzo Ide ladrillos de adobe, estabilizados con cemento portland al 6% con diferentes porcentajes de fibra de coco. El autol; para llegar a estas conclusiones, desarrolla un plan experimental en laboratorio asi como construye in situ muestras de muros con diferentes clases de ladrillos, diferentes uniones entre ellos y distintas orientaciones, para analizar el comportamiento de prototipos ante las condiciones climáticas de la zona de Tampico.

  7. Preliminary Examination of the System Fly Ash-Bottom Ash-Flue Gas Desulphurization Gypsum-Portland Cement-Water for Road Construction

    Directory of Open Access Journals (Sweden)

    R. Tokalic

    2013-01-01

    Full Text Available This paper describes an investigation into the use of three power plant wastes: fly ash, flue gas desulphurization gypsum, and bottom ash for subbase layers in road construction. Two kinds of mixtures of these wastes with Portland cement and water were made: first with fly ash consisting of coarser particles (<1.651 mm and second with fly ash consisting of smaller particles (<0.42 mm. The mass ratio of fly ash-Portland cement-flue gas desulphurization gypsum-bottom ash was the same (3 : 1 : 1 : 5 in both mixtures. For both mixtures, the compressive strength, the mineralogical composition, and the leaching characteristics were determined at different times, 7 and 28 days, after preparation. The obtained results showed that both mixtures could find a potential use for subbase layers in road construction.

  8. Geologic map of the Vancouver and Orchards quadrangles and parts of the Portland and Mount Tabor quadrangles, Clark County, Washington, and Multnomah County, Oregon

    Science.gov (United States)

    O'Connor, Jim E.; Cannon, Charles M.; Mangano, Joseph F.; Evarts, Russell C.

    2016-06-03

    IntroductionThis is a 1:24,000-scale geologic map of the Vancouver and Orchards quadrangles and parts of the Portland and Mount Tabor quadrangles in the States of Washington and Oregon. The map area is within the Portland Basin and includes most of the city of Vancouver, Washington; parts of Clark County, Washington; and a small part of northwestern Multnomah County, Oregon. The Columbia River flows through the southern part of the map area, generally forming the southern limit of mapping. Mapped Quaternary geologic units include late Pleistocene cataclysmic flood deposits, eolian deposits, and alluvium of the Columbia River and its tributaries. Older deposits include Miocene to Pleistocene alluvium from an ancestral Columbia River. Regional geologic structures are not exposed in the map area but are inferred from nearby mapping.

  9. Geospatial Analysis of Pediatric EMS Run Density and Endotracheal Intubation

    Directory of Open Access Journals (Sweden)

    Matthew Hansen

    2016-09-01

    Full Text Available Introduction: The association between geographic factors, including transport distance, and pediatric emergency medical services (EMS run clustering on out-of-hospital pediatric endotracheal intubation is unclear. The objective of this study was to determine if endotracheal intubation procedures are more likely to occur at greater distances from the hospital and near clusters of pediatric calls. Methods: This was a retrospective observational study including all EMS runs for patients less than 18 years of age from 2008 to 2014 in a geographically large and diverse Oregon county that includes densely populated urban areas near Portland and remote rural areas. We geocoded scene addresses using the automated address locator created in the cloud-based mapping platform ArcGIS, supplemented with manual address geocoding for remaining cases. We then use the Getis-Ord Gi spatial statistic feature in ArcGIS to map statistically significant spatial clusters (hot spots of pediatric EMS runs throughout the county. We then superimposed all intubation procedures performed during the study period on maps of pediatric EMS-run hot spots, pediatric population density, fire stations, and hospitals. We also performed multivariable logistic regression to determine if distance traveled to the hospital was associated with intubation after controlling for several confounding variables. Results: We identified a total of 7,797 pediatric EMS runs during the study period and 38 endotracheal intubations. In univariate analysis we found that patients who were intubated were similar to those who were not in gender and whether or not they were transported to a children’s hospital. Intubated patients tended to be transported shorter distances and were older than non-intubated patients. Increased distance from the hospital was associated with reduced odds of intubation after controlling for age, sex, scene location, and trauma system entry status in a multivariate logistic

  10. Radon in homes of the Portland, Oregon Area: Radon data from local radon testing companies collected by CRM (Continuous Radon Measurement) machines

    Science.gov (United States)

    Whitney, H.; Lindsey, K.; Linde, T.; Burns, S. F.

    2013-12-01

    Students from the Department of Geology at Portland State University paired up with the Oregon Health Authority to better understand radon gas values in homes of the Portland metropolitan area. This study focuses on radon values collected by continuous radon measurement (CRM) machines, taken by local radon testing companies. The local companies participating in this study include Alpha Environmental Services, Inc., Cascade Radon, Environmental Works, The House Detectives, LLC, and Soil Solutions Environmental Services, Inc. In total, 2491 radon readings spanning across 77 zip codes were collected from local companies in the Portland metropolitan area. The maximum value, average value, percentage of homes greater than 4 pCi/L and total rank sum was calculated and used to determine the overall radon potential for each zip code (Burns et al., 1998). A list and four maps were produced showing the results from each category. Out of the total records, 24 zip codes resulted in high radon potential and the average reading for the entire Portland Metropolitan area was 3.7 pCi/L. High potential zip codes are thought to be a result of sand and gravel (Missoula Flood deposits) and faults present in the subsurface. The CRM data was compared with both long-term and short-term data provided by the Oregon Health Authority to validate radon potentials in each zip code. If a home is located in a zip code with high or moderate radon potential across two types of data sets, it is recommended that those homes be tested for radon gas.

  11. Acción del agua de mar sobre un cemento portland de alta resistencia inicial, sobre un cemento portland resistente a los sulfatos y sobre un cemento portland: influencia de la adición de escoria. Estudio por DRX

    Directory of Open Access Journals (Sweden)

    Gaspar-Tébar, Demetrio

    1987-09-01

    Full Text Available Not available

    En este trabajo se estudia, por medio de difracción de rayos X, la evolución de las características estructurales de los compuestos cristalinos de la fracción enriquecida (cemento hidratado-atacado extraída de uno de los prismas de mortero (1:3 de 1 X 1 X 6 cm de cada una de las series de probetas fabricadas con tres cementos portland (alta resistencia inicial, cemento 1; resistente a los sulfatos, cemento 2, y normal, cemento 3 y con las mezclas cemento (1, 2 y 3/escoria = 85/15 - 65/35 - 40/60 y 30/70 (en peso, sometidas a la acción del agua de mar artificial (ASTM D 1141-75 durante 56-90-180 y 360 días, después del período de curado (1 día en cámara húmeda y 21 días bajo agua potable filtrada; del mismo modo, se estudia por DRX la composición estructural de la nueva fase sólida formada en el agua de mar artificial en donde han estado sumergidas las probetas de mortero. En los DRX de la nueva fase sólida se han identificado los picos de los compuestos cristalinos calcita, aragonito y brucita, de acuerdo con las condiciones del sistema y, de un modo especial, de las mezclas cemento/escoria utilizadas en la fabricación de las probetas de mortero. Los picos de la brucita, únicamente, se han identificado en la fase sólida formada en el agua de mar artificial en donde han estado sumergidas las probetas de mortero fabricadas con cualquiera de los cementos estudiados y con las mezclas de estos cementos con el 15% de escoria (en peso. En los DRX de la fracción enriquecida (cemento hidratado-atacado se han identificado, con intensidad variable, los picos de los compuestos cristalinos ettringita, brucita y calcita en todos los DRX y los picos de la sal de Friedel, yeso y portlandita en determinados DRX. En este trabajo, se ha puesto de manifiesto la influencia que ejerce la adición de escoria, así como el tiempo de conservación-ataque, en la formación y eliminación de los compuestos mencionados. [fr

  12. Neonatal Phosphate Nutrition Alters <em>in em>Vivo> and <em>in em>Vitro> Satellite Cell Activity in Pigs

    Directory of Open Access Journals (Sweden)

    Chad H. Stahl

    2012-05-01

    Full Text Available Satellite cell activity is necessary for postnatal skeletal muscle growth. Severe phosphate (PO4 deficiency can alter satellite cell activity, however the role of neonatal PO4 nutrition on satellite cell biology remains obscure. Twenty-one piglets (1 day of age, 1.8 ± 0.2 kg BW were pair-fed liquid diets that were either PO4 adequate (0.9% total P, supra-adequate (1.2% total P in PO4 requirement or deficient (0.7% total P in PO4 content for 12 days. Body weight was recorded daily and blood samples collected every 6 days. At day 12, pigs were orally dosed with BrdU and 12 h later, satellite cells were isolated. Satellite cells were also cultured <em>in vitroem> for 7 days to determine if PO4 nutrition alters their ability to proceed through their myogenic lineage. Dietary PO4 deficiency resulted in reduced (<em>P> < 0.05 sera PO4 and parathyroid hormone (PTH concentrations, while supra-adequate dietary PO4 improved (<em>P> < 0.05 feed conversion efficiency as compared to the PO4 adequate group. <em>In vivoem> satellite cell proliferation was reduced (<em>P> < 0.05 among the PO4 deficient pigs, and these cells had altered <em>in vitroem> expression of markers of myogenic progression. Further work to better understand early nutritional programming of satellite cells and the potential benefits of emphasizing early PO4 nutrition for future lean growth potential is warranted.

  13. Effect of Combined Calcium Hydroxide and Accelerated Portland Cement on Bone Formation and Soft Tissue Healing in Dog Bone Lesions

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    Khorshidi H

    2015-09-01

    Full Text Available Statement of Problem: Recent literatures show that accelerated Portland cement (APC and calcium hydroxide Ca (OH2 may have the potential to promote the bone regeneration. However, certain clinical studies reveal consistency of Ca (OH2, as one of the practical drawbacks of the material when used alone. To overcome such inconvenience, the combination of the Ca (OH2 with a bone replacement material could offer a convenient solution. Objectives: To evaluate the soft tissue healing and bone regeneration in the periodontal intrabony osseous defects using accelerated Portland cement (APC in combination with calcium hydroxide Ca (OH2, as a filling material. Materials and Methods: Five healthy adult mongrel dogs aged 2-3 years old (approximately 20 kg in weight with intact dentition and healthy periodontium were selected for this study. Two one-wall defects in both mesial and distal aspects of the 3rd premolars of both sides of the mandible were created. Therefore, four defects were prepared in each dog. Three defects in each dog were randomly filled with one of the following materials: APC alone, APC mixed with Ca (OH2, and Ca (OH2 alone. The fourth defect was left empty (control. Upon clinical examination of the sutured sites, the amount of dehiscence from the adjacent tooth was measured after two and eight weeks, using a periodontal probe mesiodistally. For histometric analysis, the degree of new bone formation was estimated at the end of the eighth postoperative week, by a differential point-counting method. The percentage of the defect volume occupied by new osteoid or trabecular bone was recorded. Results: Measurement of wound dehiscence during the second week revealed that all five APCs had an exposure of 1-2 mm and at the end of the study all samples showed 3-4 mm exposure across the surface of the graft material, whereas the Ca (OH2, control, and APC + Ca (OH2 groups did not show any exposure at the end of the eighth week of the study. The most

  14. Influence of mixture ratio and pH to solidification/stabilization process of hospital solid waste incineration ash in Portland cement.

    Science.gov (United States)

    Sobiecka, Elzbieta; Obraniak, Andrzej; Antizar-Ladislao, Blanca

    2014-09-01

    Solidification/stabilization (S/S) is an established utilization technology to treat hazardous wastes. This research explored the influence of pH (3-12) on the immobilization of heavy metals present in five mixtures of hospital solid waste incinerator ash and Portland cement, following two different processes of waste solidification/stabilization (cement hydration and granulation). In general, cement hydration process resulted in more stable products than granulation process. A high ash content in the mixture with Portland cement (60wt%) resulted in the highest immobilization of Pb(2+) and Cu(2+), while a low ash content in the mixture (10wt%) resulted in the lowest leachability of Zn(2+). When ash and Portland cement was mixed in equal proportions (50wt%) the highest encapsulation was observed for Ni(2+), Cd(2+) and Cr(3+). Neutral and weak alkaline pH values within the range pH=7-8 resulted in the lowest leachability of the monitored heavy metals.

  15. Quantitative Analysis of the Mineralogical Stages of the Clinkers of Portland Cement. Qualitative and Quantitative Analysis, by Infrared Spectroscopy of the Mineralogical Stages of the Clinker of Portland Cement

    Directory of Open Access Journals (Sweden)

    Käsner, Bernd

    1972-09-01

    Full Text Available Not availablePara la determinación cuantitativa de las fases mineralógicas del clinker de cemento portland, tan sólo se emplean el análisis microscópico y el de difracción de rayos X. Ambas técnicas exigen una preparación de muestras muy cuidadosa, lo que lleva bastante tiempo. A causa de estas circunstancias surge el interés de desarrollar un procedimiento con el que se pueda obtener resultados de exactitud y con poco trabajo, basado en la espectroscopia infrarroja. En principio existen dificultades, tanto en el método de trabajo como de interpretación de resultados. Por ejemplo, la formación y composición de las fases del clíñker se hallan sometidas a variaciones; por otra parte, aún no se ha llegado a elaborar un procedimiento para estudio por IR de sistemas que contengan varios componentes inorgánicos en estado sólido. Se ha pensado en la realización previa de análisis elementales, con los que se aclararían los de las fases minerales de los clínkeres, ya que no está aún suficientemente resuelto —a pesar de la importancia que esto representa— el análisis cuantitativo de estas fases.

  16. Liberação de flúor de cimentos ortodônticos antes e após recarga com solução fluoretada = Fluoride release of orthodontic cements before and after recharge with fluoride solution

    OpenAIRE

    Rogério Lacerda dos SANTOS

    2009-01-01

    Objetivo: O objetivo deste estudo foi comparar a liberação de flúor de cimentos de ionômero de vidro (CIV) utilizados para cimentação ortodôntica, antes e após recarga de flúor. Metodologia: Foram avaliados três CIV: Meron (VOCO), Vidrion C (SS WHITE) e Ketac-Cem (3M ESPE). A liberação de flúor foi medida através de eletrodo íon seletivo conectado a um analisador de íons após 1 h e 1, 3, 7, 14, 21 e 28 dias. Para avaliação da recarga de flúor e capacidade de retenção de flúor, os espécimes fo...

  17. Constituents from <em>Vigna em>vexillata> and Their Anti-Inflammatory Activity

    Directory of Open Access Journals (Sweden)

    Guo-Feng Chen

    2012-08-01

    Full Text Available The seeds of <em>Vigna em>genus are important food resources and there have already been many reports regarding their bioactivities. In our preliminary bioassay, the chloroform layer of methanol extracts of<em> V. vexillata em>demonstrated significant anti-inflammatory bioactivity. Therefore, the present research is aimed to purify and identify the anti-inflammatory principles of <em>V. vexillataem>. One new sterol (1 and two new isoflavones (2,3 were reported from the natural sources for the first time and their chemical structures were determined by the spectroscopic and mass spectrometric analyses. In addition, 37 known compounds were identified by comparison of their physical and spectroscopic data with those reported in the literature. Among the isolates, daidzein (23, abscisic acid (25, and quercetin (40 displayed the most significant inhibition of superoxide anion generation and elastase release.

  18. A comparative evaluation of ProRoot mineral trioxide aggregate and Portland cement as a pulpotomy medicament

    Directory of Open Access Journals (Sweden)

    Dipti Bhagat

    2016-01-01

    Full Text Available Introduction: Recently, some studies have compared mineral trioxide aggregate (MTA with portland cement (PC, concluding that the principle ingredients of PC are similar to those of MTA. The purpose of the present study was to evaluate the biocompatibility of PC as a pulpotomy medicament. Materials and Methods: Thirty premolars that scheduled for extraction for therapeutic reasons were randomly assigned to two experimental groups: ProRoot MTA (PMTA and PC. After isolation and pulp exposure, pulpotomy was carried out and pulps were dressed with PMTA and PC. After 6 months, the teeth were extracted and prepared for histological analysis based on Cox et al. criteria. The data were analyzed by Z-test of proportion with 1% of allowed error. Results: No statistically significant difference was found between the two groups with respect to inflammatory response, soft tissue organization, and dentine bridge formation (P > 0.05. Conclusions: PC was associated with similar favorable biological response to pulpotomy treatment as PMTA. The findings of this study support the idea that PC can be considered a cheaper substitute to MTA.

  19. An investigation on the use of tincal ore waste, fly ash, and coal bottom ash as Portland cement replacement materials

    Energy Technology Data Exchange (ETDEWEB)

    Kula, I.; Olgun, A.; Sevinc, V.; Erdogan, Y. [Dumlupinar University, Kutahya (Turkey). Dept. of Chemistry

    2002-02-01

    The possibility of using tincal ore waste (TW), coal bottom ash (BA), and fly ash (FA) as partial replacement in concrete was examined through a number of tests. The properties examined include setting time, compressive strength, mortar expansion, water consistency of mortar, and microstructure. The results showed that compressive strength of all specimens containing 1 wt.% of TW was higher than that of the control at the 28th day of curing. At 90 days, the contribution to strength by BA + TW and FA + TW was higher than in the concrete-prepared equivalent TW beyond 3 wt.% of Portland cement (PC) replacement. With the replacement of 3-5 wt.% of PC by TW, the compressive strength of the concrete decreased compared to control concrete. However, the values obtained are within the limit of Turkish Standards. Adding BA or FA with TW improved the performance relative to TW replacement only. Increasing replacement of TW gives rise to a higher setting time. As a result. TW, BA, and FA samples may be used as cementitious materials.

  20. Outcome prediction in home- and community-based brain injury rehabilitation using the Mayo-Portland Adaptability Inventory.

    Science.gov (United States)

    Malec, James F; Parrot, Devan; Altman, Irwin M; Swick, Shannon

    2015-01-01

    The objective of the study was to develop statistical formulas to predict levels of community participation on discharge from post-hospital brain injury rehabilitation using retrospective data analysis. Data were collected from seven geographically distinct programmes in a home- and community-based brain injury rehabilitation provider network. Participants were 642 individuals with post-traumatic brain injury. Interventions consisted of home- and community-based brain injury rehabilitation. The main outcome measure was the Mayo-Portland Adaptability Inventory (MPAI-4) Participation Index. Linear discriminant models using admission MPAI-4 Participation Index score and log chronicity correctly predicted excellent (no to minimal participation limitations), very good (very mild participation limitations), good (mild participation limitations), and limited (significant participation limitations) outcome levels at discharge. Predicting broad outcome categories for post-hospital rehabilitation programmes based on admission assessment data appears feasible and valid. Equations to provide patients and families with probability statements on admission about expected levels of outcome are provided. It is unknown to what degree these prediction equations can be reliably applied and valid in other settings.

  1. Examples of cooler reflective streets for urban heat-island mitigation : Portland cement concrete and chip seals

    Energy Technology Data Exchange (ETDEWEB)

    Pomerantz, M.; Akbari, H.; Chang, S.-C.; Levinson, R.; Pon, B.

    2003-04-30

    Part of the urban heat island effect can be attributed to dark pavements that are commonly used on streets and parking lots. In this paper we consider two light colored, hence cooler, alternative paving materials that are in actual use in cities today. These are Portland cement concrete (PCC) pavements and chip seals. We report measurements of the albedos of some PCC and chip sealed pavements in the San Francisco Bay Area. The albedos of the PCC pavements ranged from about 0.18 to 0.35. The temperatures of some PCC pavements are also measured and calculated. We then consider how the albedos of the constituent materials of the PCC (stone, sand and cement) contribute to the albedos of the resulting finished concrete. The albedos of a set of chip sealed pavements in San Jose, CA, were measured and correlated with the times of their placement. It is found that the albedos decrease with age (and use) but remain higher than that of standard asphalt concrete (AC) for about five years. After t hat, the albedos of the chip seals are about 0.12, similar to aged AC. The fact that many PCC pavements have albedos at least twice as high as aged AC suggests that it is possible to have pavement albedos that remain high for many years.

  2. Effect of Nanosilica on the Fresh Properties of Cement-Based Grouting Material in the Portland-Sulphoaluminate Composite System

    Directory of Open Access Journals (Sweden)

    Shengli Li

    2016-01-01

    Full Text Available The effect of NS particle size and content on the fresh properties of the grouting material based on the portland-sulphoaluminate composite system was analyzed. The experimental results indicated that air content increased and apparent density decreased, with increased NS content, but the NS particle sizes have minimal effect on the air content and apparent density. The setting time of mortar was significantly shortened, with increased NS content; however, NS particle sizes had little influence on the setting time. The effect of fluidity on the mortars adding NS with particle size of 30 nm is larger than NS with particle sizes of 15 and 50 nm and the fluidity decreased with increased NS content, but the fluidity of mortars with the particle sizes of 15 and 50 nm is almost not affected by the NS content. XRD analysis shows that the formation of ettringite was promoted and the process of hydration reaction of cement was accelerated with the addition of NS. At the microscopic level, the interfacial transition zone (ITZ of the grouting material became denser and the formation of C-S-H gel was promoted after adding NS.

  3. Portland clinker production with carbonatite waste and tire-derived fuel: crystallochemistry of minor and trace elements

    Directory of Open Access Journals (Sweden)

    F. R. D. Andrade

    2014-12-01

    Full Text Available This paper presents results on the composition of Portland clinkers produced with non-conventional raw-materials and fuels, focusing on the distribution of selected trace elements. Clinkers produced with three different fuel compositions were sampled in an industrial plant, where all other parameters were kept unchanged. The fuels have chemical fingerprints, which are sulfur for petroleum coke and zinc for TDF (tire-derived fuel. Presence of carbonatite in the raw materials is indicated by high amounts of strontium and phosphorous. Electron microprobe data was used to determine occupation of structural site of both C3S and C2S, and the distribution of trace elements among clinker phases. Phosphorous occurs in similar proportions in C3S and C2S; while considering its modal abundance, C3S is its main reservoir in the clinker. Sulfur is preferentially partitioned toward C2S compared to C3S. Strontium substitutes for Ca2+ mainly in C2S and in non-silicatic phases, compared to C3S.

  4. Influence of natural pozzolan, colemanite ore waste, bottom ash, and fly ash on the properties of Portland cement

    Energy Technology Data Exchange (ETDEWEB)

    Targan, S.; Olgun, A.; Erdogan, Y.; Sevinc, V. [Dumlupinar University, Kutahya (Turkey). Dept. of Chemistry

    2003-08-01

    The effect of natural pozzolan (NP), colemanite ore waste (CW), coal fly ash (FA), and coal bottom ash (BA) on the properties of cement and concrete was examined. The parameters studied included compressive strength, bending strength, volume expansion, and setting time. A number of cements were prepared (in the presence of fixed quantity of 10% FA, 10% BA, and 4% CW) by the replacement of Portland cement (PC) with NP in range of 5 - 30%. The results showed that the final setting time of cement pastes were generally accelerated when the NP replaced part of the cement. However, NP exhibited a significant retarding effect when used in combination with CW. The results also showed that the inclusion of NP at replacement levels of 5% resulted in an increase in compressive strength of the specimens compared with that of the control concrete. The replacement of PC by 10 - 15% of NP in the presence of fixed quantity of CW improves the bending strength of the specimens compared with control specimens after 60 days of curing age.

  5. Comparison of the sealing ability of mineral trioxide aggregate and Portland cement used as root-end filling materials.

    Science.gov (United States)

    Shahi, Shahriar; Yavari, Hamid R; Rahimi, Saeed; Eskandarinezhad, Mahsa; Shakouei, Sahar; Unchi, Mahsa

    2011-12-01

    Inadequate apical seal is the major cause of surgical endodontic failure. The root-end filling material used should prevent egress of potential contaminants into periapical tissue. The purpose of this study was to compare the sealing ability of four root-end filling materials: white mineral trioxide aggregate (MTA), gray MTA, white Portland cement (PC) and gray PC by dye leakage test. Ninety-six human single-rooted teeth were instrumented, and obturated with gutta-percha. After resecting the apex, an apical cavity was prepared. The teeth were randomly divided into four experimental groups (A: white MTA, B: gray MTA, C: white PC and D: gray PC; n = 20) and two control groups (positive and negative control groups; n = 8). Root-end cavities in the experimental groups were filled with the experimental materials. The teeth were exposed to Indian ink for 72 hours. The extent of dye penetration was measured with a stereomicroscope at 16× magnification. The negative controls showed no dye penetration and dye penetration was seen in the entire root-end cavity of positive controls. However, there was no statistically significant difference among the four experimental groups (P > 0.05). All retrograde filling materials tested in this study showed the same microleakage in vitro. Given the low cost and apparently similar sealing ability of PC, PC could be considered as a substitute for MTA as a root-end filling material.

  6. Experimental determination of carbonation rate in Portland cement at 25°C and relatively high CO2 partial pressure

    Science.gov (United States)

    Hernández-Rodríguez, Ana; Montegrossi, Giordano; Huet, Bruno; Virgili, Giorgio; Orlando, Andrea; Vaselli, Orlando; Marini, Luigi

    2016-04-01

    The aim of this work is to study the alteration of Portland class G Cement at ambient temperature under a relatively high CO2 partial pressure through suitably designed laboratory experiments, in which cement hydration and carbonation are taken into account separately. First, the hydration process was carried out for 28 days to identify and quantify the hydrated solid phases formed. After the completion of hydration, accompanied by partial carbonation under atmospheric conditions, the carbonation process was investigated in a stirred micro-reactor (Parr instrument) with crushed cement samples under 10 bar or more of pure CO2(g) and MilliQ water adopting different reaction times. The reaction time was varied to constrain the reaction kinetics of the carbonation process and to investigate the evolution of secondary solid phases. Chemical and mineralogical analyses (calcimetry, chemical composition, SEM and X-ray Powder Diffraction) were carried out to characterize the secondary minerals formed during cement hydration and carbonation. Water analyses were also performed at the end of each experimental run to measure the concentrations of relevant solutes. The specific surface area of hydrated cement was measured by means of the BET method to obtain the rates of cement carbonation. Experimental outcomes were simulated by means of the PhreeqC software package. The obtained results are of interest to understand the comparatively fast cement alteration in CO2 production wells with damaged casing.

  7. Follow up of the glassy phase formation as silicon oxide was added to Brownmillerite phase of Portland cement clinker

    Energy Technology Data Exchange (ETDEWEB)

    Hassaan, M. Y., E-mail: yousry@tedata.net.eg; Salem, S. M.; Ebrahim, F. M. [Al-Azhar University, Moessbauer Lab, Physics Department, Faculty of Science (Egypt)

    2009-01-15

    Brownmillerite phase is one of the four main phases of Portland cement clinker. It was prepared as pure C{sub 4}AF{sup 1} and C{sub 4}AF with different amount of SiO{sub 2}, (5, 10, 15, 20, 25, and 40 mol%) by addition. Pure C{sub 4}AF was prepared using CaO, Al{sub 2}O{sub 3} and Fe{sub 2}O{sub 3} according to the ratios 4:1:1. Each sample mixture was fired at 1,400 deg. C for 1 h then ground and introduced again to 1,400 deg. C for 1/2 h then quenched in air. The prepared samples were ground and measured using x-ray diffraction, scanning electron microscope, A.C. conductivity and Moessbauer spectroscopy. The results were correlated and discussed. The main finding is the formation of a glassy phase besides the C{sub 4}AF structure, in addition to the formation of the C{sub 2}S phase of cement clinker as SiO{sub 2} addition was upgraded. The electrical conductivity results showed that the 20 mol% SiO{sub 2} sample has the lowest ({sigma}) value.

  8. In vitro cytotoxicity of white MTA, MTA Fillapex® and Portland cement on human periodontal ligament fibroblasts.

    Science.gov (United States)

    Yoshino, Patrícia; Nishiyama, Celso Kenji; Modena, Karin Cristina da Silva; Santos, Carlos Ferreira; Sipert, Carla Renata

    2013-01-01

    The aim of this study was to compare the in vitro cytotoxicity of white mineral trioxide aggregate (MTA), MTA Fillapex® and Portland cement (PC) on human cultured periodontal ligament fibroblasts. Periodontal ligament fibroblast culture was established and the cells were used for cytotoxic tests after the fourth passage. Cell density was set at 1.25 X10 4 cells/well in 96-well plates. Endodontic material extracts were prepared by placing sealer/cement specimens (5x3mm) in 1mL of culture medium for 72 h. The extracts were then serially two-fold diluted and inserted into the cell-seeded wells for 24, 48 and 72 h. MTT assay was employed for analysis of cell viability. Cell supernatants were tested for nitric oxide using the Griess reagent system. MTA presented cytotoxic effect in undiluted extracts at 24 and 72 h. MTA Fillapex® presented the highest cytotoxic levels with important cell viability reduction for pure extracts and at ½ and ¼ dilutions. In this study, PC did not induce alterations in fibroblast viability. Nitric oxide was detected in extract-treated cell supernatants and also in the extracts only, suggesting presence of nitrite in the soluble content of the tested materials. In the present study, MTA Fillapex displayed the highest cytotoxic effect on periodontal ligament fibroblasts followed by white MTA and PC.

  9. Microstructure and mechanical properties of microwave-assisted heating of pozzolan-Portland cement paste at a very early stage

    Directory of Open Access Journals (Sweden)

    Natt Makul

    2013-12-01

    Full Text Available Portland-pozzolan cement pastes at a very early stage subjecting to microwave heating were investigated. Microwave with a 2.45 GHz and multimode cavity was used for the experiments. The pastes containing pozzolan materials (pulverized fuel ash, metakaolin and silica fume were proportioned with a 0.38 water/solid mass ratio and a 20% by weight replacement of total solid content. It was observed that the temperature increased continuously during microwave heating. Some ettringite rods and amorphous C-S-H fibers appear at 4 hrs. The metakaolin-cement paste exhibited little difference between the watercured and microwave-cured pastes. For the silica fume-cement paste the SF particles under microwave curing had dispersed more than with the 4 hr–cement paste. The produced phases included calcium silicate hydrate, calcium hydroxide and xenotile. The pastes can be developed in compressive strength quite rapidly and also consumed more Ca(OH2 in the pozzolan reaction to produce more C-S-H.

  10. Determinación volumétrica de la sílice en el cemento Portland

    Directory of Open Access Journals (Sweden)

    Calleja, J.

    1966-09-01

    Full Text Available Not availableSe describe un método volumétrico para la determinación cuantitativa de la sílice en el cemento portland, basado en la precipitación de la misma como fluorosilicato potásico, hidrólisis de esta sal insoluble en las condiciones de ensayo y valoración del ácido fluorhídrico liberado, con una disolución de hidróxido sódico. El método da valores reproducibles con muy escasa dispersión. La diferencia entre los valores más dispares de series de diez determinaciones hechas en una misma muestra por el mismo operador, son del orden de la tolerada por las normas A.S.T.M. (método gravimétrico para valores de un mismo operador obtenidos sobre una muestra. La diferencia entre cualesquiera otros dos valores de las series, o entre uno cualquiera de ellos y la media correspondiente a dicha serie, es muy inferior al margen de tolerancia de la A.S.T.M. Finalmente, entre el valor gravimétrico según el método de las normas A.S.T.M. y los valores volumétricos obtenidos por el método descrito, a la media de ellos, existe una concordancia aceptable.

  11. Reaproveitamento de cinzas de carvão mineral na formulação de argamassas Reuse of ash coal in the formulation of mortars

    Directory of Open Access Journals (Sweden)

    J. S. Siqueira

    2012-06-01

    Full Text Available Este trabalho tem como objetivo o estudo da incorporação de cinzas provenientes da combustão do carvão mineral em caldeiras de leito fluidizado, na produção de argamassas, em substituição parcial do cimento. Foram elaborados corpos de prova utilizando-se os cimentos Portland com as especificações CPII-E-32 de características normais e areia de classificação abaixo da malha 100. Foram preparadas misturas na proporção 4 partes de agregado e 1 parte de cimento, com a inserção de cinzas nas proporções 0, 10, 20, 30, 40 e 50%. A argamassa foi desenvolvida em misturador e a moldagem foi feita em moldes de 5 cm x 10 cm. Foi analisado o comportamento de resistência à compressão após 28 dias. A resistência diminui conforme o aumento da porcentagem de cinzas. Foram feitas análises complementares de difração de raios X e constatou-se que a substituição desse resíduo pode ser feita com sucesso em argamassas com teores de até 30%.This paper aims to study the ash incorporation from the combustion of coal in fluidized bed boilers, in production of mortar, replacing part of cement. Specimens were prepared using Portland cement to the specifications CPII-E-32 of normal characteristics and classification of sand below 100 mesh. Blends in the 4:1 ratio, that is, 4 parts of aggregate to 1 part of cement, with insertion of ashes in the proportions 0, 10, 20, 30, 40 and 50%. The mortar was developed in mixing and casting was made in a mold of 5 cm x 10 cm. The behavior of compressive strength was evaluated after 28 days; the strength decreases with increasing percentage of ash. Additional analysis was carried out by X-ray diffraction, and it was found that the substitution of this waste can be successfully used in mortars with blends of up to 30%.

  12. The Antimicrobial Efficacy of <em>Elaeis guineensisem>: Characterization, <em>in Vitroem> and <em>in Vivoem> Studies

    Directory of Open Access Journals (Sweden)

    Sreenivasan Sasidharan

    2012-04-01

    Full Text Available The urgent need to treat multi-drug resistant pathogenic microorganisms in chronically infected patients has given rise to the development of new antimicrobials from natural resources. We have tested <em>Elaeis guineensis em>Jacq> em>(Arecaceae methanol extract against a variety of bacterial, fungal and yeast strains associated with infections. Our studies have demonstrated that <em>E. guineensisem> exhibits excellent antimicrobial activity <em>in vitroem> and <em>in vivoem> against the bacterial and fungal strains tested. A marked inhibitory effect of the <em>E. guineensisem> extracts was observed against <em>C. albicansem> whereby <em>E. guineensisem> extract at ½, 1, or 2 times the MIC significantly inhibited <em>C. albicansem> growth with a noticeable drop in optical density (OD of the bacterial culture. This finding confirmed the anticandidal activity of the extract on <em>C. albicansem>. Imaging using scanning (SEM and transmission (TEM electron microscopy was done to determine the major alterations in the microstructure of the extract-treated <em>C. albicansem>. The main abnormalities noted via SEM and TEM studies were the alteration in morphology of the yeast cells. <em>In vivoem> antimicrobial activity was studies in mice that had been inoculated with <em>C. albicansem> and exhibited good anticandidal activity. The authors conclude that the extract may be used as a candidate for the development of anticandidal agent.<em> em>

  13. Efficient Heterologous Transformation of <em>Chlamydomonas> reinhardtiiem> <em>npq2em> Mutant with the Zeaxanthin Epoxidase Gene Isolated and Characterized from<em> Chlorella zofingiensisem>

    Directory of Open Access Journals (Sweden)

    Herminia Rodríguez

    2012-09-01

    Full Text Available In the violaxanthin cycle, the violaxanthin de-epoxidase and zeaxanthin epoxidase catalyze the inter-conversion between violaxanthin and zeaxanthin in both plants and green algae. The zeaxanthin epoxidase gene from the green microalga <em>Chlorella zofingiensisem> (<em>Czzep> has been isolated<em>. em>This gene encodes a polypeptide of 596 amino acids. A single copy of <em>Czzep> has been found in the <em>C. zofingiensisem> genome by Southern blot analysis. qPCR analysis has shown that transcript levels of <em>Czzep> were increased after zeaxanthin formation under high light conditions. The functionality of <em>Czzep> gene by heterologous genetic complementation in the <em>Chlamydomonas> mutant <em>npq2em>, which lacks zeaxanthin epoxidase (ZEP activity and accumulates zeaxanthin in all conditions, was analyzed. The <em>Czzep> gene was adequately inserted in the pSI105 vector and expressed in <em>npq2em>. The positive transformants were able to efficiently convert zeaxanthin into violaxanthin, as well as to restore their maximum quantum efficiency of the PSII (Fv/Fm. These results show that <em>Chlamydomonas> can be an efficient tool for heterologous expression and metabolic engineering for biotechnological applications.

  14. PERCEPÇÃO DO TRABALHO DOCENTE EM UMA UNIVERSIDADE DA REGIÃO NORTE DO BRASIL

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    Rozilaine Redi Lago

    Full Text Available Buscou-se conhecer a percepção da experiência do trabalho docente em cursos de saúde de uma universidade federal da região Norte do Brasil. Utilizando-se abordagem qualitativa, foram entrevistados seis docentes de cursos de saúde dessa universidade, cujos dados foram submetidos à análise de conteúdo. Predominaram mulheres na função docente, e a valorização dessa função como vínculo estável de trabalho, fonte de rendimentos e função social. No trabalho docente, a maioria se concentra no desenvolvimento de habilidades técnico-científicas dos alunos, expressando a necessidade da qualificação contínua e apoio institucional insuficiente. As relações pessoais desses docentes com alunos e outros professores e técnico-administrativos são reconhecidamente mediadoras da qualidade do processo de ensino-apren-dizagem e trabalho. Quanto à saúde, a maior parte se sente vulnerável e desgastada, principalmente em aspectos psicoemocionais, o que influencia as suas relações sociais dentro e fora do ambiente de trabalho. Embora o exercício profissional tenha sido identificado como fonte de estabilidade, realização pessoal e financeira, destacam-se a precariedade e a sobrecarga de trabalho, que tendem a induzir sofrimento e adoe-cimento. Esta reflexão entre docentes, movimentos sindicais e instituições de ensino pode subsidiar ajustes institucionais, legais, curriculares e sociais para melhorar o processo de ensino-aprendizagem e a qualidade de vida dos docentes.

  15. Dermatoses em renais cronicos em terapia dialitica

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    Luis Alberto Batista Peres

    2014-03-01

    Full Text Available Objetivo: As desordens cutâneas e das mucosas são comuns em pacientes em hemodiálise a longo prazo. A diálise prolonga a expectativa de vida, dando tempo para a manifestação destas anormalidades. Os objetivos deste estudo foram avaliar a prevalência de problemas dermatológicos em pacientes com doença renal crônica (DRC em hemodiálise. Métodos: Cento e quarenta e cinco pacientes com doença renal crônica em hemodiálise foram estudados. Todos os pacientes foram completamente analisados para as alterações cutâneas, de cabelos, mucosas e unhas por um único examinador e foram coletados dados de exames laboratoriais. Os dados foram armazenados em um banco de dados do Microsolft Excel e analisados por estatística descritiva. As variáveis contínuas foram comparadas pelo teste t de Student e as variáveis categóricas utilizando o teste do qui-quadrado ou o teste Exato de Fischer, conforme adequado. Resultados: O estudo incluiu 145 pacientes, com idade média de 53,6 ± 14,7 anos, predominantemente do sexo masculino (64,1% e caucasianos (90,0%. O tempo médio de diálise foi de 43,3 ± 42,3 meses. As principais doenças subjacentes foram: hipertensão arterial em 33,8%, diabetes mellitus em 29,6% e glomerulonefrite crônica em 13,1%. As principais manifestações dermatológicas observadas foram: xerose em 109 (75,2%, equimose em 87 (60,0%, prurido em 78 (53,8% e lentigo em 33 (22,8% pacientes. Conclusão: O nosso estudo mostrou a presença de mais do que uma dermatose por paciente. As alterações cutâneas são frequentes em pacientes em diálise. Mais estudos são necessários para melhor caracterização e manejo destas dermatoses.

  16. Bioassay-Guided Isolation and Identification of Cytotoxic Compounds from <em>Gymnosperma> <em>glutinosum> Leaves

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    Cristina Rodríguez-Padilla

    2012-09-01

    Full Text Available Bioassay-guided fractionation of hexane extracts of<em> Gymnosperma glutinosumem> (Asteraceae leaves, collected in North Mexico, afforded the known compounds hentriacontane (1 and (+-13<em>S>,14<em>R>,15-trihydroxy-<em>ent>-labd-7-ene (2, as well as the new <em>ent>-labdane diterpene (−-13<em>S>,14<em>R>,15-trihydroxy-7-oxo-<em>ent>-labd-8(9-ene (3. In addition, D-glycero-D-galactoheptitol (4 was isolated from the methanolic extract of this plant. Their structures were established on the basis of high-field 1D- and 2D NMR methods supported by HR-MS data. The cytotoxic activity was determined by using the <em>in vitroem> L5178Y-R lymphoma murine model. Hentriacontane (1 and the new <em>ent>-labdane 3 showed weak cytotoxicity, whereas the <em>ent>-labdane 2 showed significant (<em>p> < 0.05 and concentration dependent cytotoxicity (up to 78% against L5178Y-R cells at concentrations ranging from 7.8 to 250 µg/mL.

  17. Reaction of CO2 and brine at the interface between Portland cement and casing steel: Application to CO2 sequestration

    Science.gov (United States)

    Carey, J. W.; Zhang, J.; Lichtner, P. C.; Grigg, R.; Svec, B.; Pawar, R.

    2008-12-01

    Prediction of CO2 leakage through wellbore systems is a multiscale problem in geologic sequestration. In order for wellbore leakage to occur, km-scale processes must deliver CO2 from the point of injection to the wellbore. But, in order for the wellbore to actually leak, μm-scale processes must operate to allow CO2 to flow up the wellbore. In this study, we describe experiments and modeling of microscale processes accompanying CO2 leakage along the cement-casing interface. This work fits within a broader predictive study of CO2 sequestration performance (Viswanathan et al. 2008, Env Sci and Tech, in press) that includes calculation of CO2-migration times to wellbores. Experiments carried out in this report consisted of synthetic wellbore systems constructed of Portland cement and casing-grade steel in which a mixture of CO2 and brine were forced along the cement-casing interface at in situ sequestration conditions (40 °C and 14 MPa). The CO2-brine mixture was pre- equilibrated by flow through limestone before encountering the cement-casing composite. (The limestone- equilibrated fluid was calculated to be strongly out of equilibrium with both cement and the casing.) We used a high CO2-brine flux (10-20 ml/hour along the interface) and hypothesized that the interface would widen with time due to dissolution of either or both cement and steel. In addition to experiments, we conducted reactive transport modeling of cement reactivity using FLOTRAN, which was modified to allow representation of solid solution in the dominant cement phase, calcium-silicate-hydrate. We also developed a corrosion model for the steel. The experimental results showed that the steel was more reactive than the Portland cement. Extensive deposits or oxidation products of FeCO3-rich material developed at the interface and in some places led to an apparent closure of the interface despite the large flux through the system. In contrast, alteration of the cement appeared to be limited by

  18. em arquitetura e urbanismo

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    Ana Maria Sala Minucci Martins

    2006-01-01

    Full Text Available Está sendo desenvolvido projeto de pesquisa denominado Geometria Fractal e suas Aplicações em Arquitetura e Urbanismo, com o fito de estudar e desenvolver ferramentas analíticas e propositivas para serem aplicadas em arquitetura e urbanismo, com base em conceitos provenientes da geometria fractal.

  19. Antimicrobial Activity of Geranium Oil against Clinical Strains<em> em>of <em>Staphylococcus aureusem>

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    Monika Sienkiewicz

    2012-08-01

    Full Text Available The aim of this work was to investigate the antibacterial properties of geranium oil obtained from <em>Pelargonium graveolensem> Ait. (family <em>Geraniaceae>, against one standard <em>S. aureus em>strain ATCC 433000 and seventy clinical <em>S. aureusem> strains. The agar dilution method was used for assessment of bacterial growth inhibition at various concentrations of geranium oil. Susceptibility testing of the clinical strains to antibiotics was carried out using the disk-diffusion and E-test methods. The results of our experiment showed that the oil from <em>P. graveolensem> has strong activity against all of the clinical <em>S. aureusem> isolates—including multidrug resistant strains, MRSA strains and MLSB-positive strains—exhibiting MIC values of 0.25–2.50 μL/mL.

  20. Evaluation of Photocatalytic Properties of Portland Cement Blended with Titanium Oxynitride (TiO2−xNy Nanoparticles

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    Juan D. Cohen

    2015-07-01

    Full Text Available Photocatalytic activity of Portland cement pastes blended with nanoparticles of titanium oxynitride (TiO2−xNy was studied. Samples with different percentages of TiO2−xNy (0.0%, 0.5%, 1%, 3% and TiO2 (1%, 3% were evaluated in order to study their self-cleaning properties. The presence of nitrogen in the tetragonal structure of TiO2 was evidenced by X-ray diffraction (XRD as a shift of the peaks in the 2θ axis. The samples were prepared with a water/cement ratio of 0.5 and a concentration of Rhodamine B of 0.5 g/L. After 65 h of curing time, the samples were irradiated with UV lamps to evaluate the reduction of the pigment. The color analysis was carried out using a Spectrometer UV/Vis measuring the coordinates CIE (Commission Internationale de l’Eclairage L*, a*, b*, and with special attention to the reddish tones (Rhodamine B color which correspond to a* values greater than zero. Additionally, samples with 0.5%, 1%, 3% of TiO2−xNy and 1%, 3% of TiO2 were evaluated under visible light with the purpose of determining the Rhodamine B abatement to wavelengths greater than 400 nm. The results have shown a similar behavior for both additions under UV light irradiation, with 3% being the addition with the highest photocatalytic efficiency obtained. However, TiO2−xNy showed activity under irradiation with visible light, unlike TiO2, which can only be activated under UV light.

  1. Determinación complexométrica de trióxido de azufre en el cemento Portland

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    Calleja, J.

    1960-12-01

    Full Text Available Not availableSe describe un método volumétrico (complexométrico para la determinación cuantitativa del trióxido de azufre en el cemento portland, basado en el ataque de la muestra con ácido nítrico, precipitación del trióxido de azufre con nitrato de plomo, redisolución del precipitado con tartrato sodopotásico amortiguamiento de la disolución a pH = 10 y valoración del plomo por complexometría con EDTA (complexonsa III utilizando como indicador negro de eriocromo T. Los resultados concuerdan con los obtenidos por el método gravimétrico clásico (precipitación del trióxido de azufre con cloruro bárico. La diferencia entre dos valores obtenidos por un mismo operador con la misma muestra, aplicando el método propuesto, están dentro de la tolerancia admitida por las normas A. S. T. M. para el método gravimétrico. La diferencia entre valores volumétricos y gravimétricos correspondientes a una misma muestra también entran dentro de dicha tolerancia. El método descrito tiene la ventaja de ser más rápido, no requerir calcinación y poder ser aplicado por cualquier operador con los medios ordinarios de un laboratorio.

  2. Effect of high doses of chemical admixtures on the strength development and freeze-thaw durability of portland cement mortar

    Science.gov (United States)

    Korhonen, Charles J.

    This thesis examines the low-temperature strength development of portland cement concrete made with high doses of chemical admixtures dissolved in the mixing water and the possible beneficial effect of these admixtures on that concrete's long-term freeze-thaw durability. The literature shows that high doses of chemical admixtures can protect fresh concrete against freezing and that, under certain conditions, these admixtures can enhance the freeze-thaw durability of concrete. The challenge is that there are no acceptance standards in the U.S. that allow chemicals to be used to protect concrete against freezing. Also, the perception is that chemicals might somehow harm the concrete. This perception seems to be based on the fact that deicing salts, when applied to concrete pavement, cause roadways to scale away. This study investigated the effect of high doses of commercially available admixtures on fresh concrete while it gained strength at low temperature and on hardened concrete exposed to repeated cycles of freezing and thawing in a moist environment. The reason for studying off-the-shelf admixtures was that these materials are approved for use in concrete; they were already governed by their own set of standards. Four mortars were examined, each with a different cement and water content, when dosed with five commercial admixtures. This allowed the fresh mortar to gain appreciable strength when it was kept at nearly -10C. The admixtures also enhanced the freeze-thaw durability of the mortar, even when it was not air-entrained. Clearly, as the dosage of admixture increased beyond approximately 22% by weight of water, the mortar appeared to be unaffected by up to 700 cycles of freezing and thawing.

  3. Translational and rotational dynamics of water contained in aged Portland cement pastes studied by quasi-elastic neutron scattering.

    Science.gov (United States)

    Li, Hua; Zhang, Li-Li; Yi, Zhou; Fratini, Emiliano; Baglioni, Piero; Chen, Sow-Hsin

    2015-08-15

    Cement is a widely used construction material in the world. The quality and durability of aged cement pastes have a strong relationship with the water contained in it. The translational and rotational dynamics of water in ordinary Portland cement (OPC) pastes cured for 7, 14 and 30days were studied by analyzing Quasi-elastic Neutron Scattering (QENS) data. The effect of a new super-plasticizer (SP) additive was also studied by comparing the samples with and without the additive. By fitting the QENS spectra with the Jump-diffusion and Rotation-diffusion Model (JRM), six important parameters including the bound water index (BWI), the self-diffusion coefficient, D(t), the average residence time, τ0, the rotational diffusion constant, D(r), the rotational residence time, τ(r), and the mean squared displacement (MSD), 〈u(2)〉, were obtained. From these parameters, we can quantitatively follow the evolution of the bound water fraction (BWI). We can clearly see the different time ranges for the translational and rotational dynamics of water contained in the OPC pastes by τ0 and τ(r). From the MSD values compared with those of molecular dynamics simulation, we can distinguish between immobile water (mainly bound water) and mobile water, which includes confined water and ultraconfined water. Furthermore, by the fitted parameters' values and their change of slopes with increasing setting time for cement pastes with and without additive SP, it becomes clear that the effect of additive SP is to make the mobile water more confined and induce a more uniform the aging process during the evolution of the OPC pastes.

  4. Effect of Water to Cement Ratio and Age on Portland Composite Cement Mortar Porosity, Strength and Evaporation Rate

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    Enamur R. Latifee

    2016-08-01

    Full Text Available Durability and the compressive strength of concrete are directly related to the porosity. Water to cement ratio is the main parameter behind the nature and amount of pores within the matrix. Porosity is also influenced by the degree of cement hydration and the length of moist-curing. Even after the standard moist curing period, i.e. 28 days the concrete can gain strength and porosity can be reduced under ambient relative humidity and temperature. However, this fact, that is the age effect on porosity reduction of the cement mortar or concrete, kept in air with ambient relative humidity and temperature for long duration could not be found in the literature. Therefore, in this research, different w/c were used with constant amount Portland Composite Cement to find out whether the mortar porosity decreases significantly over time, after 28 days of water curing, while kept in air and if there is any interaction effect between the age of the mortar and different w/c; regarding porosity. It was also intended to find out if water-loss rate variation with different w/c has similar trend as porosity variation with different w/c. It was found that, there is significant decrease in porosity with time for the first six weeks in air and after that it dwindles down gradually, and there is no interaction between age and w/c. Also, after 100 days in air, samples were submerged under water for 24 hours and then kept in air for the evaporation in subsequent days. It has been found that the water evaporation vs. w/c curve, using 11-day evaporation of water from different w/c specimens in ambient condition is almost parallel to porosity vs. w/c curve. Therefore, 11-day evaporation of aged saturated mortar or concrete sample, such as core can also be used as a durability index, which can be used for old structure evaluation.

  5. Solidificación-Estabilización de Cromo, Níquel y Plomo en una Matriz Sólida de Hormigón Fabricada con Cemento Portland Solidification-Stabilization of Chromium, Nickel and Lead in a Concrete Solid Matrix of Portland Cement

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    René A Lara-Díaz

    2009-01-01

    Full Text Available Se validó la técnica de cementación como alternativa para la solidificación-estabilización de residuos sintéticos de metales pesados, cromo, níquel y plomo, usando probetas sólidas de hormigón de cemento Portland. El proceso de cementación se realiza a partir de una mezcla base para obtener hormigón con resistencia a la compresión de 29.4 N/mm², los metales fueron incorporados como sales metálicas en el agua de amasado. Se realizaron pruebas de resistencia a la compresión, lixiviación de metales por la prueba PECT con absorción atómica y se calculó la eficiencia de retención. El hormigón fabricado con cemento Portland es adecuado para su uso en la solidificación-estabilización de níquel y plomo a una concentración máxima de 0.43% para níquel y 1.94% para plomo.The technique of cementation was validated as an alternative method for the solidification-stabilization of heavy metal synthetic wastes, chromium, nickel and lead, using concrete solid cylinders made of Portland cement. The cementation process takes place starting with a concrete mixture base with compressive strength of 29.4 N/mm². Metals were incorporated as metallic salts in the mixing water. Tests of compressive strength, leaching of metals by PECT with atomic absorption were performed and retention efficiencies were calculated. Concrete made with Portland cement is appropriate for the solidification-stabilization of nickel and lead, with maximum concentrations of 0.43% of nickel and 1.94% of lead in concrete.

  6. EM International. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    1993-07-01

    It is the intent of EM International to describe the Office of Environmental Restoration and Waste Management`s (EM`s) various roles and responsibilities within the international community. Cooperative agreements and programs, descriptions of projects and technologies, and synopses of visits to international sites are all highlighted in this semiannual journal. Focus on EM programs in this issue is on international collaboration in vitrification projects. Technology highlights covers: in situ sealing for contaminated sites; and remote sensors for toxic pollutants. Section on profiles of countries includes: Arctic contamination by the former Soviet Union, and EM activities with Germany--cooperative arrangements.

  7. Portland Group推出新一代支持x86平台的NVIDIA CUDA架构编译器

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    ST全资子公司、全球领先的高性能计算(HPC)技术提供商Portland Group宣布PGI CUDA C和C++编译器已正式出货,针对基于产业标准的通用64位和32位x86架构的处理器系统。CUDA是英伟达(NVIDIA)开发的并行计算架构,可利用NVIDIA GPU(图形处理器)的动态提升系统计算性能。

  8. Mossbauer Effect Study of the Hyper fine Structure of the Different Phases of Iron in the Portland Cement Produced in Qatar

    OpenAIRE

    Eissa, N. A. [نبيل عيسى; Sallam, H. A.; Al-Houty, L.; Al-Mauraikhy, M.

    1981-01-01

    Various samples of the raw materials used in the manufacture of Portland cement in Qatar, the clinker produced and the cement itself were studied by using Mossbauer Effect and X-ray diffraction analysis in order to investigate the hyperfine structure of the iron forms present and the distribution of these forms among the different phases of the cement. The results obtained revealed the presence of five forms of iron in the cement clinker (a) Fe3"1" ions in octahedral sites existed in the ferr...

  9. Evaluation of bacterial leakage of four root- end filling materials: Gray Pro Root MTA, White Pro Root MTA, Root MTA and Portland Cement (type I

    Directory of Open Access Journals (Sweden)

    Zarabian M.

    2005-07-01

    Full Text Available Background and Aim: Today several materials have been used for root- end filling in endodontic surgery. Optimal properties of Pro Root MTA in in-vitro and in-vivo studies has been proven. On the other hand, based on some studies, Root MTA (Iranian Pro Root MTA and Portland cement are similar to Pro Root MTA in physical and biologic properties. The aim of this study was to evaluate bacterial leakage (amount and mean leakage time of four root- end filling materials. Materials and Methods: In this experimental in-vitro study, seventy six extracted single- rooted human teeth were randomly divided into six groups for root-end filling with gray Pro Root MTA, white Pro Root MTA, Root MTA (Iranian Pro Root MTA, Portland Cement (type I and positive and negative control groups. Root canals were instrumented using the step- back technique. Root- end filling materials were placed in 3mm ultra sonic retro preparations. Samples and microleakage model system were sterilized in autoclave. The apical 3-4 mm of the roots were immersed in phenol red with 3% lactose broth culture medium. The coronal access of each specimen was inoculated every 24h with a suspension of Streptococcus sanguis (ATCC 10556. Culture media were observed every 24h for colour change indicating bacterial contamination for 60 days. Statistical analysis was performed using log- rank test with P<0.05 as the limit of significance. Results: At the end of study 50%, 56.25%, 56.25% and 50% of specimens filled with Gray Pro Root MTA, White Pro Root MTA. Root MTA and Portland Cement (type I had evidence of leakage respectively. The mean leakage time was 37.19±6.29, 36.44±5.81, 37.69±5.97 and 34.81±6.67 days respectively. Statistical analysis of data showed no significant difference among the leakage (amount and mean leakage time of the four tested root- end filling materials (P=0.9958. Conclusion: Based on the results of this study, there were no significant differences in leakage among the four

  10. Microsatellite Loci in the Gypsophyte <em>Lepidium subulatum em>(Brassicaceae, and Transferability to Other <em>Lepidieae>

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    José Gabriel Segarra-Moragues

    2012-09-01

    Full Text Available Polymorphic microsatellite markers were developed for the Ibero-North African, strict gypsophyte <em>Lepidium subulatumem> to unravel the effects of habitat fragmentation in levels of genetic diversity, genetic structure and gene flow among its populations. Using 454 pyrosequencing 12 microsatellite loci including di- and tri-nucleotide repeats were characterized in <em>L. subulatumem>. They amplified a total of 80 alleles (2–12 alleles per locus in a sample of 35 individuals of <em>L. subulatumem>, showing relatively high levels of genetic diversity, <em>H>O = 0.645, <em>H>E = 0.627. Cross-species transferability of all 12 loci was successful for the Iberian endemics <em>Lepidium cardaminesem>, <em>Lepidium stylatumem>, and the widespread, <em>Lepidium graminifoliumem> and one species each of two related genera, <em>Cardaria drabaem> and <em>Coronopus didymusem>. These microsatellite primers will be useful to investigate genetic diversity, population structure and to address conservation genetics in species of <em>Lepidium>.

  11. New Trifluoromethyl Triazolopyrimidines as Anti-<em>Plasmodium> <em>falciparum> Agents

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    Núbia Boechat

    2012-07-01

    Full Text Available According to the World Health Organization, half of the World’s population, approximately 3.3 billion people, is at risk for developing malaria. Nearly 700,000 deaths each year are associated with the disease. Control of the disease in humans still relies on chemotherapy. Drug resistance is a limiting factor, and the search for new drugs is important. We have designed and synthesized new 2-(trifluoromethyl[1,2,4]triazolo[1,5-<em>a>]pyrimidine derivatives based on bioisosteric replacement of functional groups on the anti-malarial compounds mefloquine and amodiaquine. This approach enabled us to investigate the impact of: (i ring bioisosteric replacement; (ii a CF3 group substituted at the 2-position of the [1,2,4]triazolo[1,5-<em>a>]pyrimidine scaffold and (iii a range of amines as substituents at the 7-position of the of heterocyclic ring; on <em>in vitroem> activity against <em>Plasmodium falciparumem>. According to docking simulations, the synthesized compounds are able to interact with <em>P. falciparumem> dihydroorotate dehydrogenase (<em>Pf>DHODH through strong hydrogen bonds. The presence of a trifluoromethyl group at the 2-position of the [1,2,4]triazolo[1,5-<em>a>]pyrimidine ring led to increased drug activity. Thirteen compounds were found to be active, with IC50 values ranging from 0.023 to 20 µM in the anti-HRP2 and hypoxanthine assays. The selectivity index (SI of the most active derivatives 5, 8, 11 and 16 was found to vary from 1,003 to 18,478.

  12. Screening and Analysis of the Potential Bioactive Components in Rabbit Plasma after Oral Administration of Hot-Water Extracts from Leaves of <em>B>ambusa em>>textilis em>McClure

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    Jia Sun

    2012-07-01

    Full Text Available <em>Bambusa textilisem> McClure is a traditional Chinese medicinal plant belonging to the Bambusoideae subfamily and used to treat chronic fever and infectious diseases. To investigate the bioactive compounds absorbed in the rabbit blood after oral administration of hot-<em>water extractem>>s from em>>the leaves of em>>B. textilisem> McClure, a validated chromatographic fingerprint method was established using LC-Q-TOF-MS. Twenty compounds in bamboo leaves and three potential bioactive compounds in rabbit plasma were detected. Of the twenty detected compounds <em>in vitroem>, fifteen of which were tentatively identified either by comparing the retention time and mass spectrometry data with that of reference compounds or by reviewing the literature. Three potential bioactive compounds, including (<em>E-p>-coumaric acid, (<em>Z-p>-coumaric acid, and apigenin-8-<em>C>-β-D-(2"-<em>O>-α-L-rhamnosyl-gluco-pyranoside, were detected in both <em>the leaves of em>>B. textilis em>McClure and rabbit plasma. Of the three compounds, apigenin-8-<em>C>-β-D-(2"-<em>O>-α-L-rhamnosylglucopyranoside was identified based on its UV, MS, and NMR spectra. This study provides helpful chemical information for further pharmacology and active mechanism research on <em>B. textilisem> McClure.

  13. Aplicaciones prácticas de la espectroscopía de absorción infrarroja en el estudio de los crudos, del clínker y del cemento portland anhidro

    Directory of Open Access Journals (Sweden)

    Vázquez, Tomás

    1980-09-01

    Full Text Available Not available

    En la primera parte de este trabajo (* se trató brevemente y de una manera fundamentalmente práctica el estudio por espectroscopía infrarroja de calizas, arcillas, clínker portland y sus fases constituyentes. En, el presente trabajo finalizará esta exposición con una visión general de algunas posibilidades que tiene la espectroscopía IR en el estudio del cemento portland anhidro, así como el estudio breve de puzolanas, escorias y cenizas volantes, como adiciones activas.

  14. Infiltração marginal em restaurações de resina composta com diferentes materiais adesivos intermediários = Marginal leakage in resin composite restorations lined with different adhesive materials

    Directory of Open Access Journals (Sweden)

    Moraes, Rafael Stanziona de

    2007-01-01

    Full Text Available Este estudo avaliou a capacidade de selamento de restaurações de resina composta com diferentes materiais adesivos intermediários. Cavidades Classe V padronizadas, com margens em esmalte e dentina/cemento, foram confeccionadas em incisivos bovinos. A resina de alto escoamento Fill Magic (Vigodent e o cimento ionomérico Vitremer (3M ESPE foram empregados como intermediários de restaurações com os compósitos Charisma e Solitaire (Heraeus Kulzer, formando 6 grupos (n = 14: [C1] – compósito microhíbrido Charisma; [C2] – Fill Magic + Charisma; [C3] – Vitremer + Charisma; [S1] – compósito condensável Solitaire; [S2] – Fill magic + Solitaire; [S3] – Vitremer + Solitaire. Após acabamento e polimento, as amostras foram armazenadas em solução fisiológica a 37ºC, por 30 dias, e então imersas em solução de fucsina básica a 0,5% por 24h. Os dentes foram longitudinalmente seccionados e a penetração do corante avaliada sob magnificância (40×, por dois examinadores, com escores padronizados. Os dados foram submetidos ao teste estatístico não-paramétrico de Kruskal-Wallis. Nas margens em esmalte, diferenças significativas foram verificadas apenas para a associação de intermediários à resina Solitaire, com os grupos S2 (p < 0,05 e S3 (p < 0,001 apresentando escores de infiltração significativamente maiores em relação aos demais. As margens em dentina/cemento apresentaram maior penetração em relação às margens em esmalte (p < 0,001. Apenas a associação do Vitremer às duas resinas melhorou o selamento deste substrato, com os grupos C3 (p < 0,001 e S3 (p < 0,05 apresentando os menores escores de infiltração

  15. Genotoxicity of <em>Euphorbia hirtaem>: An <em>Allium cepaem> Assay

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    Kwan Yuet Ping

    2012-06-01

    Full Text Available The potential genotoxic effects of methanolic extracts of <em>Euphorbia hirta em>which is commonly used in traditional medicine to treat a variety of diseased conditions including asthma, coughs, diarrhea and dysentery was investigated using <em>Allium cepaem> assay. The extracts of 125, 250, 500 and 1,000 µg/mL were tested on root meristems of <em>A. cepaem>. Ethylmethanesulfonate was used as positive control and distilled water was used as negative control. The result showed that mitotic index decreased as the concentrations of <em>E. hirtaem> extract increased. A dose-dependent increase of chromosome aberrations was also observed. Abnormalities scored were stickiness, c-mitosis, bridges and vagrant chromosomes. Micronucleated cells were also observed at interphase. Result of this study confirmed that the methanol extracts of <em>E. hirta em>exerted significant genotoxic and mitodepressive effects at 1,000 µg/mL.

  16. <em>In Vitroem> Antioxidant Properties of Flavonoids and Polysaccharides Extract from Tobacco (<em>Nicotiana> em>tabacum> L. Leaves

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    Jing-Lu Wang

    2012-09-01

    Full Text Available In the present study, antioxidant properties of flavonoids and polysaccharides from tobacco (<em>Nicotiana> tabacumem> L. leaves were evaluated in several <em>in vitroem> systems, e.g., scavenging activities on hydroxyl, superoxide anion, 1,1-diphenyl-2-picrylhydrazyl (DPPH and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid (ABTS radicals, and reducing power. Flavonoids showed much better activity than polysaccharides in scavenging activities on free radicals. When compared to the positive control, ascorbic acid, both showed weaker antioxidant potential. However, flavonoids possessed comparable superoxide anion, DPPH and ABTS radical scavenging abilities to ascorbic acid at high concentration (600 μg/mL. Meanwhile, it was found that flavonoids had prominent effects on the reducing power, which was equivalent to ascorbic acid, and was significantly higher than polysaccharides. These results clearly indicate that flavonoids are effective in scavenging free radicals and have the potential to be powerful antioxidants. Thus, tobacco leaves could be considered as a potential source of natural antioxidants for food, pharmaceutical, cosmetics or nutraceutical industries.

  17. Freeze-Thaw Performance and Moisture-Induced Damage Resistance of Base Course Stabilized with Slow Setting Bitumen Emulsion-Portland Cement Additives

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    Mojtaba Shojaei Baghini

    2015-01-01

    Full Text Available Freeze-thaw (FT cycles and moisture susceptibility are important factors influencing the geotechnical characteristics of soil-aggregates. Given the lack of published information on the behavior of cement-bitumen emulsion-treated base (CBETB under environmental conditions, especially freezing and thawing, this study investigated the effects of these additives on the CBETB performance. The primary goal was to evaluate the resistance of CBETB to moisture damage by performing FT, Marshall conditioning, and AASHTO T-283 tests and to evaluate the long-term stripping susceptibility of CBETB while also predicting the liquid antistripping additives to assess the mixture’s durability and workability. Specimens were stabilized with Portland cement (0%–6%, bitumen emulsion (0%–5%, and Portland cement-bitumen emulsion mixtures and cured for 7 days, and their short- and long-term performances were studied. Evaluation results of both the Marshall stability ratio and the tensile strength ratio show that the additions of additives increase the resistance of the mixtures to moisture damage. Results of durability tests performed for determining the resistance of compacted specimens to repeated FT cycles indicate that the specimen with the 4% cement-3% bitumen emulsion mixture significantly improves water absorption, volume changes, and weight losses. This indicates the effectiveness of this additive as a road base stabilizer with excellent engineering properties for cold regions.

  18. Effect of Curing Regime on Degree of Al3+Substituting for Si4+in C-S-H Gels of Hardened Portland Cement Pastes

    Institute of Scientific and Technical Information of China (English)

    HU Chenguang; HU Shuguang; DING Qingjun; FENG Xiaoxin; HUANG Xiulin

    2014-01-01

    The effect of curing regime on degree of Al3+substituting for Si4+(Al/Si ratio) in C-S-H gels of hardened Portland cement pastes was investigated by 29Si magic angel spinning (MAS) nuclear magnetic resonance (NMR) with deconvolution technique. The curing regimes included the constant temperature (20, 40, 60 and 80℃) and variable temperature (simulated internal temperature of mass concrete with 60℃peak). The results indicate that constant temperature of 20℃is beneficial to substitution of Al3+for Si4+, and Al/Si ratio changes to be steady after 180 d. The increase of Al/Si ratio at 40℃is less than that at 20℃for 28 d. The other three regimes of high temperature increase Al/Si ratio only before 3 d, on the contrary to that from 3 to 28 d. However, the 20℃curing stage from 28 to 180 d at variable temperature regime, is beneficial to the increase of Al/Si ratio which is still lower than that at constant temperature regime of 20℃for the same age. A nonlinear relation exists between the Al/Si ratio and temperature variation or mean chain length (MCL) of C-S-H gels, furthermore, the amount of Al3+which can occupy the bridging tetrahedra sites in C-S-H structure is insufficient in hardened Portland cement pastes.

  19. Chemical composition, effective atomic number and electron density study of trommel sieve waste (TSW), Portland cement, lime, pointing and their admixtures with TSW in different proportions.

    Science.gov (United States)

    Kurudirek, Murat; Aygun, Murat; Erzeneoğlu, Salih Zeki

    2010-06-01

    The trommel sieve waste (TSW) which forms during the boron ore production is considered to be a promising building material with its use as an admixture with Portland cement and is considered to be an alternative radiation shielding material, also. Thus, having knowledge on the chemical composition and radiation interaction properties of TSW as compared to other building materials is of importance. In the present study, chemical compositions of the materials used have been determined using a wavelength dispersive X-ray fluorescence spectrometer (WDXRFS). Also, TSW, some commonly used building materials (Portland cement, lime and pointing) and their admixtures with TSW have been investigated in terms of total mass attenuation coefficients (mu/rho), photon interaction cross sections (sigma(t)), effective atomic numbers (Z(eff)) and effective electron densities (N(e)) by using X-rays at 22.1, 25keV and gamma-rays at 88keV photon energies. Possible conclusions were drawn with respect to the variations in photon energy and chemical composition.

  20. Vulnerability of water systems to the effects of climate change and urbanization: a comparison of Phoenix, Arizona and Portland, Oregon (USA).

    Science.gov (United States)

    Larson, Kelli L; Polsky, Colin; Gober, Patricia; Chang, Heejun; Shandas, Vivek

    2013-07-01

    The coupled processes of climate change and urbanization pose challenges for water resource management in cities worldwide. Comparing the vulnerabilities of water systems in Phoenix, Arizona and Portland, Oregon, this paper examines (1) exposures to these stressors, (2) sensitivities to the associated impacts, and (3) adaptive capacities for responding to realized or anticipated impacts. Based on a case study and survey-based approach, common points of vulnerability include: rising exposures to drier, warmer summers, and suburban growth; increasing sensitivities based on demand hardening; and limited capacities due to institutional and pro-growth pressures. Yet each region also exhibits unique vulnerabilities. Comparatively, Portland shows: amplified exposures to seasonal climatic extremes, heightened sensitivity based on less diversified municipal water sources and policies that favor more trees and other irrigated vegetation, and diminished adaptive capacities because of limited attention to demand management and climate planning for water resources. Phoenix exhibits elevated exposure from rapid growth, heightened sensitivities due to high water demands and widespread increases in residential and commercial uses, and limited adaptive capacities due to weak land use planning and "smart growth" strategies. Unique points of vulnerability suggest pathways for adapting to urban-environmental change, whether through water management or land planning. Greater coordination between the land and water sectors would substantially reduce vulnerabilities in the study regions and beyond.