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  1. 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

  2. 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

  3. 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.

  4. Alternativas analíticas para determinação de ferro e titânio em cimento Portland

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    Franco Jr. Jorge de O.; Korn Maria das Graças A.; Costa Antonio Celso S.; Santos Jr. Anibal de Freitas; Teixeira Leonardo S. G.

    2001-01-01

    In the present work four different analytical methodologies were studied for the determination of iron and titanium in Portland cement. The cement samples were dissolved with hot HCl and HF, being compared Fe and Ti concentrations through four analytical methods: molecular absorption spectrophotometry using the reagents 1,2-hydroxybenzene-3,5-disulfonic acid (Tiron) and the 5-chloro-salicylic acid (CSA), inductively coupled plasma atomic emission spectrometry (ICP-AES) and flame atomic absorp...

  5. Alternativas analíticas para determinação de ferro e titânio em cimento Portland

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    Franco Jr. Jorge de O.

    2001-01-01

    Full Text Available In the present work four different analytical methodologies were studied for the determination of iron and titanium in Portland cement. The cement samples were dissolved with hot HCl and HF, being compared Fe and Ti concentrations through four analytical methods: molecular absorption spectrophotometry using the reagents 1,2-hydroxybenzene-3,5-disulfonic acid (Tiron and the 5-chloro-salicylic acid (CSA, inductively coupled plasma atomic emission spectrometry (ICP-AES and flame atomic absorption spectrophotometry (FAAS. In the spectrophotometric determinations were studied pH conditions, reagents addition order, interferences, amount of reagents, linear range and stability of the system. In the techniques of ICP-AES and FAAS were studied the best lines, interferences, sensibility and linear range. The obtained results were compared and the agreement was evaluated among the methods for the determination of the metals of interest.

  6. Decomposição da fase majoritária do cimento Portland - Parte I: Alita Pura

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    Jorge Alberto Soares Tenório; Fernando Gabriel da Silva Araújo; Sérgio Sônego Raymundo Pereira; Andréa Vidal Ferreira; Denise Crocce Romano Espinosa; Alexandre Barros

    2003-01-01

    As propriedades mecânicas do cimento Portland estão intrinsecamente relacionadas à composição química do clínquer, em especial à concentração de silicato tricálcico 3CaO.SiO2, ou C3S. No processo produtivo industrial, o clínquer deve ser resfriado rapidamente, para evitar a decomposição do silicato tricálcico em silicato dicálcico e cal. Esse trabalho estuda a cinética de decomposição térmica do C3S puro. A decomposição do C3S puro em resfriamento contínuo apresentou uma velocidade mais eleva...

  7. Alternativas analíticas para determinação de ferro e titânio em cimento Portland Comparative study of analytical methods for iron and titanium determination in Portland cement

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    Jorge de O. Franco Jr.; Maria das Graças A. Korn; Antonio Celso S. Costa; Anibal de Freitas Santos Jr.; Leonardo S. G. Teixeira

    2001-01-01

    In the present work four different analytical methodologies were studied for the determination of iron and titanium in Portland cement. The cement samples were dissolved with hot HCl and HF, being compared Fe and Ti concentrations through four analytical methods: molecular absorption spectrophotometry using the reagents 1,2-hydroxybenzene-3,5-disulfonic acid (Tiron) and the 5-chloro-salicylic acid (CSA), inductively coupled plasma atomic emission spectrometry (ICP-AES) and flame atomic absorp...

  8. 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.

  9. 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)

  10. Utilização de rejeitos de pilha zinco-carvão em argamassas e concretos de cimento Portland Waste preparing of zinc battery for use in mortar and concrete materials of portland cement

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    Coimbra, M. A.; W. Libardi; M. R. Morelli

    2004-01-01

    O objetivo deste trabalho foi recuperar um resíduo proveniente de pilhas do tipo zinco-carvão para ser utilizado como aditivo em argamassas e concretos, dando assim, uma solução para as pilhas e ao mesmo tempo ajudando a resolver a questão ambiental incluindo-as na indústria brasileira de reciclagem. Desse modo, foi possível caracterizar e avaliar as possibilidades de utilização desse rejeito. Foram coletadas pilhas para serem caracterizadas através de diferentes análises, assim como, densida...

  11. Utilização de rejeitos de pilha zinco-carvão em argamassas e concretos de cimento Portland Waste preparing of zinc battery for use in mortar and concrete materials of portland cement

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    M. A. Coimbra

    2004-12-01

    Full Text Available O objetivo deste trabalho foi recuperar um resíduo proveniente de pilhas do tipo zinco-carvão para ser utilizado como aditivo em argamassas e concretos, dando assim, uma solução para as pilhas e ao mesmo tempo ajudando a resolver a questão ambiental incluindo-as na indústria brasileira de reciclagem. Desse modo, foi possível caracterizar e avaliar as possibilidades de utilização desse rejeito. Foram coletadas pilhas para serem caracterizadas através de diferentes análises, assim como, densidade real e área específica (BET. Também se utilizou a técnica de difração de raios X, pH e microscopia eletrônica de varredura em conjunto com espectroscopia dispersiva de energia por raios X.The aim of this work was to recover one waste from zinc battery by use like additive in mortar and concrete materials and this way, promoting both battery and environment solutions. Hence, the morphological, chemical and mineralogical characterizations were made focusing its use in the recycling Brazilian industry. Moreover, the tests performed in a true density and specific surface area (BET, X-ray diffraction, pH and scanning electron microscopy with energy dispersive spectroscopy (EDS.

  12. 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

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    M. S. Picanço; R. S. Angélica; M. S. Barata

    2011-01-01

    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 nece...

  13. 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

  14. 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.

  15. Decomposição da fase majoritária do cimento Portland - Parte II: alita com adições de Fe e Al

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    Jorge Alberto Soares Tenório; Fernando Gabriel da Silva Araújo; Sérgio Sônego Raymundo Pereira; Andréa Vidal Ferreira; Denise Crocce Romano Espinosa; Alexandre Barros

    2003-01-01

    As propriedades do cimento Portland estão diretamente relacionadas às concentrações de suas fases constituintes, principalmente a alita, a belita, a fase ferrítica e o aluminato. A alita, de composição 3CaO.SiO2 e abreviada por C3S, deve ser o constituinte majoritário do clínquer após o processamento, pois é sua reação de hidratação que confere a resistência mecânica ao cimento curado. A belita, de composição 2CaO.SiO2 e abreviada por C2S, está presente como o primeiro complexo de cal e sílic...

  16. Estudo de argilas calcinadas para produção de cimento portland pozolânico na Região de Curitiba, Paraná - Brasil

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    Christófolli, Jorge Luiz

    2010-01-01

    Resumo: Algumas razões importantes justificam a necessidade do estudo de novas formas de explorar os recursos naturais de nosso planeta e assegurar a sustentabilidade da existência humana. Dentre as diversas áreas do conhecimento, a engenharia civil tem o dever e obrigação de viabilizar suas atividades e minimizar os impactos das obras através de ações que reduzam o consumo de energia, que aumentem a durabilidade das construções e que causem menor impacto ambiental. O uso de cimentos portland...

  17. The strength retrogression of special class Portland oilwell cement Regressão de resistência de um cimento Portland classe especial para cimentação de poço de petróleo

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    U. T. Bezerra

    2011-06-01

    Full Text Available Temperatures in excess of 110 ºC result in phase transformations of cement, significantly decreasing its compressive strength. This effect is referred to as strength retrogression. It is frequently observed in cement sheaths of heavy oil wells submitted to steam injection. The present study evaluated the mechanical behavior of Special Class Portland Oilwell Cement (SCPOC slurries containing silica flour to prevent retrogression. A factorial statistical planning was used to assess the effect of the main variables on the mechanical behavior of cement slurries, i.e., mechanical testing temperature (30, 100, 120, 180 and 230 ºC; contents of silica flour replacing cement (0-18 and 36% and curing time for rupture (12 h and 7 days. The results revealed that slurries containing 18% of silica flour tested at 230 ºC depicted an increase in compressive strength up to 30% after curing for 12 h and 10% after curing for 7 days, indicating retrogression. On the other hand, testing slurries containing silica flour at temperatures up to 180 ºC revealed strength increase of just 10%, suggesting the mechanical stability of the SCPOC, which prevents retrogression. Such behavior was probably related to the relatively low content of C3A and low specific area of the material. Therefore, strength retrogression at typical bottom hole temperatures of up to 180 ºC can be controlled by small additions of silica flour, economically contributing to the use of SCPOC cementing.Temperaturas superiores a 110 ºC provocam mudanças de fase nos cimentos, reduzindo de forma significativa sua resistência à compressão. Isto é observado com frequência em bainhas de cimento em poços de petróleo pesado, que são submetidos a injeção de vapor. O presente estudo avaliou o comportamento mecânico de pastas para cimentação preparadas com um cimento portland Classe especial contendo silica flour para prevenção da regressão de resistência. Um planejamento fatorial foi

  18. 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

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    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

  19. 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

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    Panzera, T. H.; A. L. R. Sabariz; K. Strecker; Borges, P. H. R.; D. C. L. Vasconcelos; W. L. Wasconcelos

    2010-01-01

    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 aument...

  20. 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

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    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.

  1. Thermal model for rotary kiln used in the production of Portland cement clinker; Modelo termico para forno rotativo utilizado para produzir clinquer de cimento Portland

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    Duarte, Vanisa C.; Menon, Genesio J.; Silva, Rogerio J. [Escola Federal de Engenharia de Itajuba, MG (Brazil). Dept. de Mecanica

    1998-07-01

    This paper presents a heat transfer model for a rotary kiln used for producing clinker of Portland cement. The temperatures will depend only on position throughout length of the kiln and time. It has been considered the heat loss through wall and the transferred heat to the solids. The finite element method has been utilized on a one-dimensional representation basis. From the results obtained it was possible to evaluate the kiln behavior, as starting point for a study of co-incineration of waste. (author)

  2. 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)

  3. In vitro evaluation of the antimicrobial activity of endodontic sealers Avaliação in vitro da atividade antimicrobiana de cimentos endodônticos

    Directory of Open Access Journals (Sweden)

    Daniela Cristina Miyagak

    2006-12-01

    Full Text Available The purpose of this study is to evaluate the antimicrobial activity of the endodontic sealers: N-Rickert, Sealapex, AH Plus, Mineral Trioxide Aggregate (MTA and portland cement. The Agar diffusion method was used in plates previously inoculated with the following microorganisms: C. albicans, S. aureus, E. faecalis, E. coli. The diameters of microbial inhibition zones were measured after 24 hours of incubation in kiln at 37°C. According to the methodology used, it was possible to conclude that only the sealers AH Plus and N-Rickert presented antimicrobial activity against C. albicans, S. aureus, and E. coli; no antimicrobial activity in MTA, Sealapex and portland cement was observed. N-Rickert presented the largest inhibition zones varying from 8 to 18 mm, and the microorganism E. faecalis was resistant against all sealers tested.O objetivo deste estudo é avaliar a capacidade antimicrobiana dos cimentos obturadores de canal: N-Rickert, Sealapex, AH Plus e também do Agregado Trióxido Mineral (MTA e Cimento de Portland. O método utilizado foi a difusão em Ágar, em placas previamente inoculadas com os seguintes microorganismos: C. albicans, S. aureus, E. faecalis, E. coli. A leitura do diâmetro do halo de inibição do crescimento microbiano foi realizada, após 24 horas de incubação, em estufa a 37°C. De acordo com a metodologia empregada, foi possível concluir que: somente os cimentos obturadores AH Plus e N-Rickert apresentaram atividade antimicrobiana contra C. albicans, S. aureus e E. coli; não foi observada atividade antimicrobiana no cimento de Portland, MTA e Sealapex. O cimento N-Rickert apresentou halos de inibição maiores variando de 8 a 18 mm. O microorganismo E. faecalis foi resistente contra todos os cimentos testados.

  4. Estudo para o aproveitamento de resíduos pétreos de marmorarias, como agregados para concreto de cimento Portland

    OpenAIRE

    Fábio Conrado de Queiroz; Maria Heloisa Barros de Oliveira Frascá

    2008-01-01

    In this paper, it is presented a study for the utilization of marble shops waste (stone by-products) as aggregate of Portland cement concrete. First, the material were separated and classified by lithologic type. After that, they were mixed in a crusher, producing the required aggregates. Several tests for technological characterization of the material were done, intending to evaluate the use of the material as aggregate. Some simulations of Portland cement concrete dosage were done with vari...

  5. Influência da incorporação de lodo de estação de tratamento de água (ETA nas propriedades tecnológicas de tijolos solo-cimento

    Directory of Open Access Journals (Sweden)

    L. P. Rodrigues

    2013-12-01

    Full Text Available As estações de tratamento de água são unidades industriais empregadas em grande escala no tratamento de água doce bruta para o consumo humano. No entanto, o processo de tratamento de água bruta gera enorme volume de lodo que necessita ser descartado. No Brasil este lodo tem sido descartado principalmente nos recursos hídricos mais próximos, resultando em problemas ambientais, econômicos e sociais. Neste trabalho foi feito um estudo objetivando avaliar a influência da adição do lodo de estação de tratamento de água (ETA sobre as propriedades tecnológicas de tijolo solo-cimento para uso na construção civil. As matérias-primas utilizadas foram solo, lodo de ETA e cimento Portland. Corpos cimentício cilíndricos contendo até 5% em peso de lodo de ETA em substituição parcial do solo foram preparados por prensagem uniaxial e curados em câmara úmida por 28 dias. Os tijolos solo-cimento foram caracterizados em termos de absorção de água, massa específica bulk e resistência à compressão simples. Análise microestrutural dos tijolos curados foi acompanhada por microscopia confocal e difração de raios X. Os resultados indicaram que a incorporação do lodo de ETA influencia diretamente nas propriedades tecnológicas dos tijolos solo-cimento. Além do mais, o lodo de ETA estudado pode ser incorporado em tijolo solo-cimento numa quantidade de até 1,25% em peso como substituto parcial do solo natural.

  6. 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)

  7. 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.

  8. Processo de trabalho e riscos para a saúde dos trabalhadores em uma indústria de cimento

    OpenAIRE

    Fátima Sueli Neto Ribeiro; Simone de Oliveira; Marcelo Moreno dos Reis; Célia Regina Sousa da Silva; Marco Antônio Carneiro Menezes; Ana Elisa Xavier de Oliveira e Dias; Josino Costa Moreira; Gisele Sayuri Kuryiama

    2002-01-01

    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. ...

  9. 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

    Directory of Open Access Journals (Sweden)

    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

  10. Avaliação in vitro da microinfiltração em cavidades de classe V restauradas com diferentes combinações de resina composta e cimento de ionômero de vidro In vitro evaluation of marginal leakage in class V restorations using different combinations of composite resin and glass ionomer cement

    OpenAIRE

    Zanata, Régia Luzia; PALMA Regina Guenka; Navarro, Maria Fidela de Lima

    1998-01-01

    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 componente...

  11. A influência do tipo de cimento no desempenho de concretos avançados formulados a partir do método de dosagem computacional The influence of cement type on the performance of advanced concretes designed by computing mix proportion technique

    Directory of Open Access Journals (Sweden)

    A. L. de Castro

    2011-03-01

    Full Text Available Ao se produzir uma mistura de concreto, especialmente de alto desempenho, a primeira escolha a ser feita é quanto ao tipo de cimento a ser empregado, o que faz deste ligante um material essencial para a produção desses materiais. As características reológicas de formulações de concretos de alto desempenho estão relacionadas com a hidratação dos aluminatos do cimento, enquanto o desenvolvimento da resistência mecânica é dependente dos silicatos hidratados formados. Assim, variações nas características do cimento influenciam as propriedades dos concretos, sendo observados comportamentos distintos para misturas produzidas com diferentes cimentos. O presente artigo visa avaliar a influência do tipo de cimento sobre o desempenho de concretos especiais aplicados na construção civil, dosados a partir de um método computacional. As propriedades no estado fresco foram avaliadas medindo-se o índice de fluidez e determinando-se o comportamento reológico do material. No estado endurecido, a resistência mecânica foi avaliada pelos ensaios de compressão uniaxial, tração por compressão diametral e flexão em 3 pontos, enquanto o módulo de elasticidade foi avaliado pelos métodos estático e dinâmico. Comparando-se todas as propriedades medidas, verifica-se que os concretos produzidos com cimento Portland apresentaram desempenhos superiores ao do concreto produzido com cimento aluminoso, sendo o cimento Portland de alta resistência inicial ainda mais eficiente que o cimento Portland composto com escória para a produção de misturas de alto desempenho e até os 28 dias de idade.When a concrete is produced, especially a high performance one, the first concern is the cement type to be used, making this binder an essential compound. The rheological properties of high performance concretes are related to the hydration of cement aluminates phase, whereas the development of mechanical strength depends on the hydrated silicates formed

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

    OpenAIRE

    Andréa Regina Kaneko Kobayashi; Alexandre Benetti Parreira

    2009-01-01

    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 me...

  13. 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

    Directory of Open Access Journals (Sweden)

    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

  14. 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

    OpenAIRE

    Renato Menezes; Clóvis Monteiro Bramante; Roberto Brandão Garcia; Ariadne Letra; Vanessa Graciela Gomes Carvalho; Everdan Carneiro; Sérgio Brunini; Rodrigo Cardoso de Oliveira; Giovana Calichio Canova; Fernanda Gomes de Moraes

    2004-01-01

    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 ...

  15. 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

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

    Directory of Open Access Journals (Sweden)

    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

  17. Cimento aluminoso e seus efeitos em concretos refratários magnesianos espinelizados in situ Calcium aluminate cement and its effects on in-situ spinel containing magnesia refractory castables

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    D. H Milanez

    2010-03-01

    Full Text Available O uso de concretos refratários alumina-magnésia ligados por cimento aluminoso (CAC apresenta vantagens decorrentes da presença de espinélio e de CA6 (CaO.6Al2O3, ambas formadas in-situ e acompanhadas de expansão. Estas fases possuem alta resistência a escórias básicas e ao choque térmico, propriedades estas imprescindíveis para aplicação em panelas siderúrgicas. Estudos anteriores mostraram que o teor de CAC utilizado em concretos alumina-magnésia influencia a expansão do material, principalmente devido à formação de CA6. Este trabalho visa estudar a influência do teor de cimento no sistema magnésia-alumina, utilizando-se a mesma matriz de um concreto alumina-magnésia tradicional. Os resultados indicaram que o CAC influencia na estabilidade volumétrica do sistema MgO-espinélio: quanto menor o teor de CAC, menor a retração das amostras. Isso refletiu na sinterização dos concretos e, assim, nas propriedades mecânicas após queima em temperaturas elevadas.Calcium aluminate cement (CAC bonded alumina-magnesia refractory castables present great advantages for steel ladle applications as a result of in-situ expansive formation of spinel and CA<6, which leads to high basic slag and thermal shock resistance. The CAC content in those castables strongly influences its expansive behavior mainly due to CA6 formation. In the present work, the effects of the CAC content in magnesia-alumina castables were analyzed. The results showed that calcium aluminate cement affects the volumetric stability of MgO-spinel system: the lower the CAC content, the lower the shrinkage. These effects on the sintering and in the mechanical properties after sintering at high temperatures are also presented and discussed.

  18. Misturas de um solo laterítico com cimento e bentonita para uso em cortinas verticais Mixtures of a lateritic soil with cement and bentonite for slurry wall purposes

    Directory of Open Access Journals (Sweden)

    Priscila Batista

    2010-06-01

    Full Text Available É crescente mundo afora o uso de cortinas verticais para contenção da contaminação em água subterrânea. Os solos lateríticos, pela sua ampla distribuição no Brasil, possuem grande potencial de aplicação nessas obras. Entretanto algumas questões ainda carecem de maior investigação, como a interação e compatibilidade desses solos com a bentonita e o cimento, principais aditivos usados para melhorar as propriedades das cortinas. O presente artigo avalia propriedades de um solo laterítico e suas misturas com bentonita e cimento, incluindo a investigação de parâmetros geotécnicos mecânicos e hidráulicos. A campanha laboratorial consistiu de ensaios de caracterização física, físico-química e mineralógica, de condutividade hidráulica, de compressão simples e de cisalhamento direto. Os resultados demonstram que a adição de 3% de bentonita em amostras compactadas não trouxe a diminuição esperada da condutividade hidráulica do solo laterítico, ainda que tenha proporcionado um considerável incremento na resistência ao cisalhamento da mistura.There is an increasing worldwide demand for slurry walls to contain contaminated groundwater. Lateritic soils, due to their wide distribution in the Brazilian territory, have great potential to be used in these cases. However, some issues remain uncertain and need investigation, including the interaction and compatibility of these soils with bentonite or cement, the most used additives to improve their geotechnical properties. This work evaluates some mechanical and hydraulic properties of a lateritic soil sample and its mixtures with bentonite and cement. The laboratorial procedures consisted of physical, physico-chemical and mineralogical characterization, hydraulic conductivity, uniaxial compression and direct shearing testing. The results demonstrate that the addition of 3% of bentonite in compacted samples did not decrease the hydraulic conductivity of the lateric soil as

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

    Directory of Open Access Journals (Sweden)

    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.

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

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    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.

  1. 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

  2. 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.

  3. O cimento de ionômero de vidro na odontologia

    OpenAIRE

    Ian Matos Vieira; Renata Loureiro Louro; Maria Teresa Atta; Maria Fidela Lima Navarro; Paulo Afonso Silveira Francisconi

    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 ...

  4. 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

    OpenAIRE

    Loris L. Zucco; Antonio L. Beraldo

    2008-01-01

    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...

  5. 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

  6. 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

  7. The effect of microsilica and refractory cement content on the properties of andalusite based Low Cement Castables used in aluminum casthouse O efeito do teor de microsílica e de cimento refratário nas propriedades de LCCs usados em moldagem de alumínio

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    E. A. Firoozjaei

    2010-12-01

    Full Text Available The bonding system in low cement castables is achieved by the use of calcium aluminate cement, microsilica and reactive alumina. The lime/silica ratio critically impacts the liquid phase formation at high temperatures and subsequently the corrosion resistance and the mechanical and physical properties of the refractory. In the current study, the effects of microsilica and cement contents on the corrosion resistance and the physical and mechanical properties of Andalusite Low Cement Castables (LCCs refractories were investigated. Alcoa Cup test was used to evaluate the corrosion resistance of the castables at 850 ºC and 1160 ºC. The study showed that an increase in the microsilica/cement ratio improves the physical and mechanical properties of the castable, but at the expense of the corrosion resistance. When a fixed amount of BaSO4 was added to the base refractory material, barium celsian along with glassy phase formation was observed to increase with the increase in the microsilica/cement ratio in the refractory. The presence of the glassy phases was noted to lower the positive effect of Ba-celsian formation on improving the corrosion resistance of the refractory. The observed results were validated using thermodynamic calculations which indicated that Ba-celsian phase was more resistant than Ca-anorthite for applications involving contact with molten aluminum.O sistema de ligantes em concretos de baixo cimento é produzido com o uso de cimento de aluminato de cálcio, microsílica e alumina reativa. A razão cálcia/sílica tem importância crucial na formação de fase líquida a altas temperaturas e posteriormente na resistência a corrosão e nas propriedades mecânicas e físicas do refratário. Neste trabalho foram investigados os efeitos do teor de microsílica e de cimento na resistência à corrosão e nas propriedades mecânicas e físicas de refratários de baixo teor de cimento Andalusita (LCC. O teste da Alcoa foi usado para

  8. 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.

  9. 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

  10. 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

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    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.

  11. 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)

  12. A correlation between Bogue's equations and Taylor's procedure for the evaluation of crystalline phases in special class Portland oilwell cement clinker Correlação entre as equações de Bogue e o procedimento de Taylor na avaliação das fases cristalinas de um cimento Portland especial para cimentação de poços de petróleo

    OpenAIRE

    U. T. Bezerra; A. E. Martinelli; D. M. A. Melo; M. A. F. Melo; F. M. Lima

    2011-01-01

    The crystalline composition of Portland cement clinker is commonly established by Bogue's equations, which are based on a series of assumptions that seldom apply to oilwell cements. This is probably due to the presence of additional oxides and phase reconversion upon cooling of the clinker from the calcination temperature. Important differences are therefore observed between the numerical values yielded by the mathematical equations and image analysis quantification. In this study, the concen...

  13. O cimento de ionômero de vidro na odontologia

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    Ian Matos Vieira

    2006-09-01

    Full Text Available 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 fóssulas e fissuras. Mais recentemente passou a ser o material de escolha na técnica restauradora atraumática (ART, e também tem sido utilizado na medicina e fonoaudiologia em tratamentos em regiões ósseas. Sua popularidade evidenciou-se devido as suas propriedades biologicamente favoráveis, pois apesar de ainda possuir uma solubilidade inicial crítica e um comportamento estético insatisfatório, o cimento ionomérico libera flúor para o meio bucal, possui uma adesão química à estrutura dental e demonstra ser biocompatível. Com isso, ele evidencia propriedades anticariogênicas importantes, podendo assim ser utilizado em diversas situações na odontologia.

  14. Estudo das características químicas e físicas da cinza da casca da castanha de caju para uso em materiais cimentícios - 10.4025/actascitechnol.v32i4.7434

    OpenAIRE

    Sofia Araujo Lima; João Adriano Rossignolo

    2010-01-01

    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 e químicas da cinza da casca da castanha de caju (CCCC), por meio dos seguintes ensaios: análise química, massa unitária, massa específica, extratos lixiviado e ...

  15. 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

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    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

  16. Estudo comparativo do uso isolado de plasma rico em plaquetas e combinado com cimento de alfa-fosfato tricálcico no reparo ósseo em ratos Comparative study on use of platelet-rich plasma alone and in combination with alpha-tricalcium phosphate cement for bone repair in rats

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    Alessandra Deise Sebben

    2012-01-01

    Full Text Available OBJETIVOS: Avaliar o efeito do cimento α-TCP combinado com PRP sobre a osteogênese, comparando os resultados com PRP utilizado isoladamente. MÉTODOS: Foi confeccionado defeito bilateral no fêmur de ratos e preenchido com um dos dois tipos de tratamentos (PRP ou α-TCP+PRP, sendo avaliado em quatro e oito semanas. As imagens radiográficas forneceram valores da área da lesão, e a histologia (coloração Picrosirius indicou a área de neoformação óssea. RESULTADOS: As médias referentes à área de lesão do grupo α-TCP+PRP (2,64mm² ± 2,07 e 1,91mm² ± 0,93; quatro e oito semanas, respectivamente demonstraram numericamente melhores resultados, porém não significativos (p > 0,05, em comparação com aqueles observados no grupo PRP (5,59mm² ± 2,69 e 3,23mm² ± 1,46; quatro e oito semanas, respectivamente. As médias de neoformação óssea foram de 62,7% ± 12,1% e 79,01% ± 6,25 no grupo PRP, e 73,3% ± 12,7 e 85,86% ± 10,45 no grupo α-TCP+PRP, em quatro e oito semanas, respectivamente (p > 0,05. CONCLUSÃO: Os dados deste estudo sugerem que o tratamento com cimento α-TCP combinado com PRP não demonstra diferença significativa quando comparado ao PRP isolado. Entretanto, há um possível efeito precoce sobre a regeneração óssea quando os dois biomateriais são aplicados em conjunto.OBJECTIVES: To evaluate the effect of alpha-tricalcium phosphate (α-TCP cement combined with platelet-rich plasma (PRP on osteogenesis, and to compare the results with use of PRP alone. METHODS: A bilateral defect was produced in rat femurs and was filled with one of two types of treatments (PRP or α-TCP + PRP. The outcomes were evaluated after four and eight weeks. Radiographic images provided values for the lesion area, and histology (picrosirius staining indicated the area of ​​new bone formation. RESULTS: The means relating to the lesion area of the α-TCP + PRP group (2.64 ± 2.07 and 1.91 ± 0.93 mm², after four and eight weeks

  17. 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

  18. A indústria do cimento como vector estratégico para o desenvolvimento de Moçambique: estudo de caso: Cimentos de Moçambique

    OpenAIRE

    Thay, António Hama

    2012-01-01

    Trabalho de dissertação, Mestrado em Gestão de Empresas O presente estudo debruça-se sobre a Indústria do Cimento como Vector Estratégico para o Desenvolvimento de Moçambique, estudo de caso: Cimentos de Moçambique. O trabalho faz uma abordagem tendo em conta a literatura disponível e a realidade moçambicana e sul africana. O trabalho está estruturado em 4 capítulos: No Capítulo I apresenta-se a evolução da actividade económica em Moçambique, bem como uma descrição...

  19. Comparison of the interface dentin-endodontic sealer using two SEM magnifications = Comparação da interface dentina-cimento endodôntico usando dois aumentos de MEV

    OpenAIRE

    Steier, Liviu; de Figueiredo, José Antonio Poli; Belli, Sema

    2010-01-01

    Objetivo: Este estudo teve por objetivo comparar a interface dentina – cimento endodôntico de dois cimentos (RealSeal e AH Plus) usando dois aumentos de Microscopia Eletrônica de Varredura (MEV). Metodologia: Os dois terços coronários de oito molares extraídos foram removidos e as superficies dentinárias foram desgastadas com o uso sequencial de lixas abrasivas 180 e 320, sob refrigeração a água. Os espécimes foram divididos em dois grupos com quatro espécimes cada de acordo com o cimento ...

  20. 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"

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    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

  1. 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

    OpenAIRE

    Fátima Sueli Neto Ribeiro; Simone de Oliveira; Marcelo Moreno dos Reis; Célia Regina Sousa da Silva; Marco Antônio Carneiro Menezes; Ana Elisa Xavier de Oliveira e Dias; Josino Costa Moreira; Gisele Sayuri Kuryiama

    2002-01-01

    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. ...

  2. 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

  3. 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

  4. 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

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    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

  5. 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

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    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.

  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

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    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. Produção de cimentos ósseos à base de fosfato de cálcio

    OpenAIRE

    Mansos, Patrícia Alexandra de Oliveira

    2008-01-01

    Os cimentos fosfato de cálcio (CPC) têm vindo a despertar cada vez mais interesse por apresentarem vantagens em relação a outros materiais, tais como o cimento acrílico ou os blocos cerâmicos, usualmente utilizados na reparação óssea. Estes são constituídos por um ou mais fosfato de cálcio, e uma solução líquida, originando uma pasta que endurece rapidamente, e que resulta num material cristalino, biocompatível e osteocondutor. O objectivo deste estudo foi investigar algumas das propriedades ...

  8. 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

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    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

  9. Vigas de grande vão prefabricadas em betão de alta resistência pré-esforçado : viabilidade, dimensionamento, fabrico e comportamento

    OpenAIRE

    Fernandes, Paulo Alexandre Lopes

    2007-01-01

    A prefabricação pesada em Portugal é, na sua grande maioria, constituída por um conjunto de produtos que pouca evolução conheceu nos últimos anos. Fabricados com betões que raramente ultrapassam a classe de resistência C40/50, carecem de uma abordagem mais actual. O desenvolvimento da tecnologia do betão, o fabrico em Portugal de cimento Portland CEM I 52.5 R, a disponibilização pela industria química de superplastificantes de 3ª geração e de adições de elevado efeito pozolânico, são razõe...

  10. 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)

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

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    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.

  12. 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

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    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

  13. A eficácia das medidas de recuperação ambiental implantadas em minas de calcário para cimento Effectiveness of environmental reclamation measures implemented in cement limestone mines

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    Ana Claudia Neri

    2010-06-01

    Full Text Available Esse trabalho analisa a eficácia das medidas de recuperação ambiental implantadas em nove minas de calcário. Utilizou-se o procedimento desenvolvido por Neri e Sánchez (2008, o qual envolve: (i realização de inspeções técnicas, apoiadas por um roteiro fundamentado nas boas práticas internacionais e nacionais relacionadas à recuperação ambiental em minas, (ii classificação das evidências encontradas (prática totalmente aplicada ou adaptada satisfatoriamente, parcialmente aplicada, não aplicada ou não se aplica, e (iii cálculo de índices de conformidade. Constatou-se que as atividades de planejamento apresentaram pior desempenho (baixo índice de conformidade, as práticas operacionais atingiram, em geral, resultados satisfatórios e as de gestão apresentaram nível médio de conformidade. Alguns exemplos de boas práticas são destacados. Conclui-se que as atuais práticas não apresentam boa conformidade com as melhores práticas internacionais e nacionais. Há, principalmente, deficiências de planejamento, com reflexos nas práticas operacionais, em que pese a adoção de várias práticas satisfatórias, especialmente de manejo de solo e de proteção das águas. Não há reconhecimento, por parte das empresas, da importância da gestão do processo de recuperação.The effectiveness of environmental reclamation measures implemented in limestone mines is reviewed. An assessment procedure developed by Neri and Sánchez (2008 was used. This tool comprises a set of statements of good practice grouped in three categories (essential, important and accessory practices which are assessed through (i carrying out field technical inspections guided by a series of protocols especially designed for this purpose; (ii classifying inspection evidences according to previously defined categories (totally applied or satisfactorily adapted, partially applied, not applied or not applicable; and (iii calculating conformity indexes. The

  14. 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

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    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

  15. Avaliação do emprego de carepa de aço como agregado miúdo em concreto Evaluation of the use of mill scale as fine aggregate in concrete

    OpenAIRE

    Fernanda Macedo Pereira; José Carlos Krause de Verney; Denise Maria Lenz

    2011-01-01

    A carepa de aço é um resíduo sólido gerado na etapa de laminação da fabricação do aço, normalmente depositado ao ar livre no pátio de siderúrgicas. O presente trabalho visa a avaliar a possibilidade de incorporação da carepa de aço em concretos de cimento Portland, como substituição à areia natural quartzosa. Foram produzidos concretos com traços 1:3,5; 1:5,0 e 1:6,5, com diferentes teores do resíduo (0%, 10%, 25% e 40%) e abatimento de 110±10mm, para determinação da resistência à compressão ...

  16. 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

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    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.

  17. 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

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    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 (α=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

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

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    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.

  19. 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

    OpenAIRE

    Marcos A. S. dos Anjos; Khosrow Ghavami; Normando P. Barbosa

    2003-01-01

    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 mesm...

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

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    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

  1. Estudo das propriedades dos adjuvantes na compatibilidade/robustez cimento/adjuvante

    OpenAIRE

    Coelho, Sónia Alexandra Guerreiro Báia Pessoa

    2012-01-01

    A qualidade do betão pode ser controlada pelo comportamento da fluidez da pasta de cimento, o qual está relacionado com a dispersão das partículas de cimento. Um dos maiores avanços na tecnologia do betão tem sido o desenvolvimento de aditivos. Um destes tipos de aditivos, os Superplastificantes (SP), fornecem a possibilidade de se obter uma melhor dispersão das partículas de cimento, produzindo pastas com elevada fluidez. Com o desenvolvimento de betões de alta resistência e elevado desempen...

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

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    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.

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

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    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.

  4. Avaliação da influência do cimento na interação cimento-superplastificante

    OpenAIRE

    Catarino, Joana Filipa

    2012-01-01

    Um dos materiais mais utilizados na indústria da construção civil é o betão. É um material cuja aplicação é diversificada: edifícios, pontes, barragens, entre outros e tem tido um grande desenvolvimento ao longo dos tempos. A sua ampla utilização deve-se às suas características, tais como a trabalhabilidade (no estado fresco), a durabilidade ou a resistência a cargas e ao fogo (no estado endurecido). O cimento é o principal componente para obtenção de betão, constituindo o ligante que o ma...

  5. Características físicas e mecânicas de misturas de solo, cimento e cinzas de bagaço de cana-de-açúcar Physical and mechanical characteristics of soil-cement-bagasse ash mixtures

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    Martha Del C. Mesa Valenciano

    2004-12-01

    Full Text Available Este trabalho teve por finalidade analisar algumas características de misturas de solo, cimento e cinzas de bagaço de cana-de-açúcar para sua possível utilização na fabricação de materiais alternativos de construção. Para tal, amostras de cinzas de bagaço de cana-de-açúcar foram submetidas a um tratamento prévio que consistia de peneiramento e moagem, antes de serem incorporadas às misturas de solo e cimento. Diferentes combinações de cimento-cinzas foram estudadas, determinando-se, para cada uma delas, a consistência normal e a resistência à compressão simples, aos 7 e 28 dias. Posteriormente, corpos-de-prova moldados com tais misturas de solo-cimento-cinzas foram submetidos a ensaios de compactação, compressão simples e absorção de água. Os resultados indicaram a possibilidade de substituir até 20% do cimento Portland, na mistura, por cinzas de bagaço de cana-de-açúcar, sem prejuízo da resistência à compressão simples.This work was done with the objective of studying some physical and mechanical characteristics of the sugarcane bagasse ash added to a soil-cement mixture, in order to obtain an alternative construction material. The sugarcane bagasse ash pre-treatment included both sieving and grinding, before mixing with soil and cement. Different proportions of cement-ash were tested by determining its standard consistence and its compressive resistance at 7 and 28 days age. The various treatments were subsequently applied to the specimens molded with different soil-cement-ash mixtures which in turns were submitted to compaction, unconfined compression and water absorption laboratory tests. The results showed that it is possible to replace up to 20% of Portland cement by sugarcane bagasse ash without any damage to the mixture's compressive strength.

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

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    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

  7. Orthodontic cements: immediate protection and fluoride release Cimentos ortodônticos: proteção imediata e liberação de flúor

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    Rogério Lacerda dos Santos

    2012-08-01

    Full Text Available OBJECTIVES: The objective of the authors was to evaluate fluoride release of 3 glass ionomer cements with immediate protection of fluoride varnish (Cavitine, SS White, divided into 3 groups: Group M (Meron, VOCO, Group V (Vidrion C, SS White and Group KC (Ketac-Cem, 3M ESPE. METHODS: Fluoride release was measured during 60 days by means of an ion-selective electrode connected to an ion analyzer. After 4 weeks, the test specimens were exposed to a solution of 0.221% sodium fluoride (1000 ppm of fluoride. RESULTS: Results showed that the cements reached a maximum peak of fluoride release in a period of 24 h. There was a statistically significant difference between the amount of fluoride released after the applications of fluoride among the groups from the 31st to 60th day (p> 0.05. CONCLUSION: The Vidrion C and Meron cements showed better performance to uptake and release fluoride when compared with Ketac-Cem cement.OBJETIVO: o objetivo desse estudo foi avaliar a liberação de flúor dos seguintes três cimentos de ionômero de vidro, com proteção imediata de verniz fluoretado (Cavitine, S. S. White: Meron / VOCO (Grupo M; Vidrion C / S. S. White (Grupo V; e Ketac Cem / 3M ESPE (Grupo KC. MÉTODOS: a liberação de flúor foi medida durante 60 dias, através de eletrodo íon seletivo conectado a um analisador de íons. Após quatro semanas, os corpos de prova foram expostos a uma solução de fluoreto de sódio a 0,221% (1.000ppm de flúor. RESULTADOS: os resultados evidenciaram que os cimentos atingiram o pico máximo de liberação de flúor com 24h após a presa inicial. Houve diferença estatisticamente significativa entre os grupos, quanto à quantidade de flúor liberado após as aplicações de flúor, do 31º ao 60° dia (p > 0,05. CONCLUSÃO: os cimentos Meron e Vidrion apresentaram maior capacidade de captação e liberação de flúor, em comparação ao cimento Ketac Cem.

  8. Influência de aditivos sobre a trabalhabilidade de concretos refratários de ultra-baixo teor de cimento

    OpenAIRE

    Oliveira I. R. de; Studart A. R.; Valenzuela F. A. O.; Pandolfelli V. C.

    2003-01-01

    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 aq...

  9. 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

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    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.

  10. 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.

  11. INCORPORAÇÃO DE RESÍDUOS SÓLIDOS NA FABRICAÇÃO DE TIJOLOS SOLO-CIMENTO

    Directory of Open Access Journals (Sweden)

    Josiane Rodrigues de Oliveira

    2014-03-01

    Full Text Available O modo inadequado de extração de recursos naturais e a poluição provocada por resíduos geram impactos sobre o meio ambiente. Visando oferecer alternativas de destinação dos resíduos sólidos urbanos, como os resíduos de tornearia mecânica, objetivou-se analisar as características físicas e mecânicas de tijolos compostos por misturas ternárias de solo-cimento-resíduo e avaliar a viabilidade da sua utilização em construções. Os tijolos solo-cimento-resíduo foram moldados em prensa manual, empregando 10% de cimento na mistura e diferentes teores de resíduo (0%, 10% e 15%. Após a prensagem, os tijolos foram submetidos a cura úmida por 7 dias. Os ensaios de compressão simples ocorreram aos 7 e 28 dias e os ensaios de absorção de água foram realizados aos 28 dias de idade. Os melhores resultados de resistência à compressão simples e absorção de água foram obtidos pela incorporação de 15% de resíduo na mistura. Em geral, os resultados não atenderam as recomendações das normas técnicas brasileiras pertinentes, contudo mostraram que a utilização de resíduo de tornearia mecânica para a fabricação de tijolos solo-cimento, proporcionou melhorias nas características físico-mecânicas do tijolo solo-cimento. Palavras-chave: tijolo ecológico, resíduos de tornearia mecânica, resistência à compressão. INCORPORATION OF SOLID RESIDUES FROM MECHANICAL TURNINGIN SOIL-CEMENT BRICKSMANUFACTURING ABSTRACT: The inadequate form of natural resources extraction and pollution caused by urban solid residues generate impacts on the environment. With the intent of investigate alternative for urban solid residues, such as the residues generated by mechanical turning operation, this study was accomplished with the purpose of analyze the physical and mechanical characteristics of brick composed of ternary mixtures of soil-cement-residue as well as the feasibility of its use in construction. The soil-cement-residues bricks

  12. Um cimento mais sustentável frente a um ataque severo por sulfatos

    OpenAIRE

    Alves, Maria Teresa Pinheiro; Gomà, Ferrán; Jalali, Said

    2007-01-01

    A necessidade de encontrar um cimento plenamente resistente aos sulfatos e que também seja ambientalmente sustentável levou a que se analisasse o comportamento de um cimento sulfoaluminato-belítico (SAB) frente a um ataque severo por sulfato de sódio e por sulfato de magnésio, ambos sujeitos a várias temperaturas. Efectuou-se a comparação das amostras atacadas pelos diferentes tipos de sulfato com outras intactas da mesma idade e submetidas às mesmas temperaturas do ensaio. Os resultados m...

  13. Cimentos endodônticos: análise morfológica imediata e após seis meses utilizando microscopia de força atômica Endodontic cements: morphological analysis carried out immediately and after a six-month storage, using atomic force microscopy

    Directory of Open Access Journals (Sweden)

    Marcia Carneiro VALERA

    2000-09-01

    Full Text Available O objetivo deste trabalho foi analisar a morfologia dos cimentos Sealapex, Apexit, Sealer 26 (cimentos a base de hidróxido de cálcio e Ketac Endo (cimento de ionômero de vidro, através da microscopia de força atômica, verificando-se as características de suas partículas após a obturação dos canais radiculares e após um período de seis meses de contato com o plasma sanguíneo humano. Utilizaram-se 16 dentes unirradiculares humanos extraídos e incluídos em blocos de resina após o preparo biomecânico. As raízes foram divididas em quatro grupos de quatro raízes cada e os canais radiculares obturados pela técnica de condensação lateral passiva com os cimentos em estudo. Verificou-se que o cimento Apexit foi o que mais sofreu desintegração após seis meses de imersão em plasma sanguíneo humano, seguido pelo Ketac Endo e Sealapex. Dentre todos os cimentos estudados, o Sealer 26 mostrou-se o mais uniforme e com a menor desintegração.The aim of this study was to analyze the high resolution morphological characteristics of Sealapex, Apexit, Sealer 26 (calcium hydroxide cements and Ketac Endo (glass ionomer cement, using atomic force microscopy (AFM, immediately after root canal obturation and six months after it, keeping the roots stored in human blood plasma. The AFM evaluation used 16 single-rooted human teeth embedded in resin blocks after biomechanical preparation. The samples were divided into four groups (four roots each and the passive lateral condensation filling technique was used in the obturation of the canals with the mentioned sealers. Apexit suffered the highest degree of disintegration after the six-month storage in human blood plasma, followed by Ketac Endo and Sealapex. Sealer 26 was the most uniform cement and suffered the least disintegration.

  14. 75 FR 20778 - Security Zone; Portland Rose Festival Fleet Week, Willamette River, Portland, OR

    Science.gov (United States)

    2010-04-21

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA87 Security Zone; Portland Rose Festival Fleet Week... Hawthorne and Steel Bridges in Portland, Oregon during the Portland Rose Festival Fleet Week from June 2... and other vessels participating in Fleet Week as well as the maritime public in general and will do...

  15. 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

    OpenAIRE

    Miguel Afonso Sellitto; Nelson Kadel Jr.; Miriam Borchardt; Giancarlo Medeiros Pereira; Jeferson Domingues

    2013-01-01

    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...

  16. Estudo da influência da microestrutura do clínquer sobre a moagem na fabricação de cimento: microscopia eletrônica de varredura

    OpenAIRE

    Vládia Cristina Gonçalves Souza; Carlos Hoffmann Sampaio; Luis Marcelo Marques Tavares

    2002-01-01

    Como continuação de um estudo anteriormente realizado com microscopio óptico (MO) e lupa, sobre amostras de clínquer coletadas em uma fábrica de cimento no sul do Brasil, foram realizadas análises em microscópio eletrônico de varredura (MEV). O objetivo foi buscar mais informações que pudessem ou não corroborar o resultado de alto grau de corrosão dos cristais, apontado pelos primeiros instrumentos, devido à presença de um alto conteúdo de metais. As análises em MEV mostraram a existência de ...

  17. ANÁLISE DA AÇÃO ANTIMICROBIANA DE CIMENTOS E PASTAS EMPREGADOS NA PRÁTICA ENDODÔNTICA ANALYSIS OF THE ANTIMICROBIAL ACTION OF SEALERS AND PASTES USED IN ENDODONTIC PRACTICE

    Directory of Open Access Journals (Sweden)

    Marco Antonio Hungaro DUARTE

    1997-10-01

    Full Text Available Foi avaliado o poder antimicrobiano dos cimentos Endomethasone, AH26, Sealer 26, Sealer 26 acrescido de 5% de hexametilenotetramina, Sealer 26 acrescido de 10% de hexametilenotetramina, Sealapex e pasta aquosa de hidróxido de cálcio. Foram utilizados o método de difusão radial em placas ágar escavadas e cepas puras de microorganismos, sendo que as leituras foram efetuadas após 24 e 48 horas de incubação em aerobiose e microaerofilia. Os resultados mostraram que o Endomethasone apresentou os maiores halos de inibição do crescimento bacteriano e que o acréscimo de hexametilenotetramina acarretou um aumento nos halos proporcionados pelo Sealer 26. O cimento Sealapex e a pasta de hidróxido de cálcio não inibiram os microorganismos testadosAn evaluation of the antimicrobial action of the sealers Endomethasone, AH26, Sealapex, Sealer 26, Sealer 26 with 5% hexametilenotetramine, Sealer 26 with 10% hexametilenotetramine and aqueous calcium hydroxide paste was carried out. Microorganisms were spread over hollowed agar plates, by means of the radial diffusion method. Halo measurements were done after 24 and 48 hours of incubation under aerobic and microaerophilia conditions. The results showed bigger halos when Endomethasone was used, and the increment of hexametilenotetramine in the Sealer 26 increased the inhibition halos of this sealer. The Sealapex and the calcium hydroxide paste did not inhibit bacterial growth

  18. 77 FR 4006 - Foreign-Trade Zone 45-Portland, Oregon; Expansion of Manufacturing Authority; Epson Portland, Inc...

    Science.gov (United States)

    2012-01-26

    ... Foreign-Trade Zones Board Foreign-Trade Zone 45--Portland, Oregon; Expansion of Manufacturing Authority; Epson Portland, Inc. (Inkjet Ink Manufacturing); Portland, OR An application has been submitted to the... of the scope of manufacturing authority approved within Subzone 45F, on behalf of Epson Portland,...

  19. 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...

  20. 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...

  1. 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

  2. Teor de cimento e seus efeitos sobre a resistência ao choque térmico de concretos espinelizados in-situ Cement content and the thermal shock performance of in-situ spinel formation in refractory castables

    Directory of Open Access Journals (Sweden)

    G. B. Cintra

    2008-12-01

    Full Text Available Concretos refratários aluminosos contendo espinélio são amplamente utilizados como revestimentos de panelas siderúrgicas, devido a sua elevada resistência à corrosão. Além do bom desempenho anti-corrosivo, estes materiais devem suportar as variações bruscas de temperatura causadas pela ciclagem térmica, responsáveis pela diminuição da vida útil do revestimento. Neste contexto, a análise da resistência ao dano por choque térmico se torna parâmetro fundamental para a correta seleção do revestimento refratário. Esta propriedade pode ser melhorada por meio da incorporação de mecanismos de tenacificação à estrutura do concreto. Uma fase que auxilia na tenacificação do material é o CA6, que está associada ao cimento de aluminato de cálcio (CAC, matéria-prima usada como ligante. Sendo assim, o objetivo deste trabalho é caracterizar o efeito do teor de cimento na microestrutura do concreto e suas conseqüências nos danos causados por choque térmico. Os resultados obtidos indicam que concretos com valores intermediários de cimento possuem melhor desempenho em relação ao choque térmico, nas temperaturas de uso das panelas. Dessa forma, o controle do teor de cimento possibilita aumentar a resistência ao dano por choque térmico e, consequentemente, a vida útil do revestimento.Spinel containing aluminous refractory castables are currently used in steel ladle due to their high corrosion resistance. Besides this property, these materials have to withstand sudden temperature variations caused by thermal cycling, which could be one of the main causes for shortening the lining's working life. Within this context, the thermal shock damage resistance analysis becomes a fundamental variable for the correct refractory selection. This property can be improved by toughening mechanisms, such as the presence of CA6, associated to calcium aluminate cement in the castable composition. Therefore, the objective of this work is to

  3. Urban carbon dioxide in Portland, Oregon

    Science.gov (United States)

    Bostrom, G. A.; Brooks, M.; Rice, A. L.

    2010-12-01

    Ambient concentrations of atmospheric carbon dioxide (CO2) are reported for the Portland, Oregon (USA) metropolitan region since late July, 2009. Three stationary locations were established: a downtown location on the campus of Portland State University; a residential site in southeast Portland; and a rural station on Sauvie Island, located ~30km northwest of Portland in the Columbia River Gorge. Continuous measurements of CO2 at the sites average 400-410ppm and show considerable variability due to CO2 sources, sinks and meteorological drivers of ventilation. Within this variability, a marked 20-30ppm diurnal cycle is observed due to photosynthetic activity and variations in the planetary boundary layer. In-city CO2 concentrations are on average enhanced by 5-6ppm over the Sauvie Island site during upgorge wind conditions, a difference which is greatest in the afternoon. Measurements of the 13C/12C ratio of CO2 in downtown Portland are significantly depleted in 13C relative to 12C compared with background air and suggest that regional CO2 is dominated by petroleum sources (70-80%). High degrees of relationship between CO2 variability and primary air pollutants CO and NO (r2=0.70 to 0.80), measured by the Oregon Department of Environmental Quality at the Southeast Portland location, corroborate this finding and illustrate the importance of traffic emissions on elevated ambient CO2 concentrations. In addition to CO2 at the fixed sites, measurements of street-level CO2 concentrations were obtained using a mobile instrument mounted in a bike trailer. Results from these field data show relatively homogenous CO2 concentrations throughout residential Portland neighborhoods with significant enhancements in CO2 on busy roadways or near areas of traffic congestion.

  4. 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

  5. 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.

  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...

  7. 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

    OpenAIRE

    Pithon, Matheus Melo

    2007-01-01

    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-...

  8. 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

  9. Avaliação do potencial do grits como material de construção na produção de tijolos de solo-cimento

    OpenAIRE

    Larissa de Almeida Miranda; Rita de Cássia Silva Sant' Anna Alvarenga; Paulo Cesar Moreira Pinto Junior; Eduardo Dantas de Paula Júnior; Carlos Alexandre Braz de Carvalho; Délio Porto Fassoni; Lauro Gontijo Couto

    2011-01-01

    O "grits" é um resíduo sólido de características arenosas e coloração acinzentada, gerado pela indústria de polpa kraft durante a etapa de recuperação do licor branco empregado no cozimento dos cavacos de madeira. O objetivo deste trabalho foi estudar o potencial do grits como material de construção, considerando-se a sua empregabilidade na fabricação de tijolos de solo-cimento. Para a determinação da quantidade ideal de resíduo a ser utilizada, foram estudados os traços em volume 1:14:0; 1:1...

  10. 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

  11. INFILTRAÇÃO MARGINAL DE CIMENTOS IONOMÉRICOS MODIFICADOS POR RESINA MICROLEAKAGE OF RESIN-MODIFIED GLASS IONOMER CEMENT

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo CARRARA

    1997-04-01

    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 (pThe microleakage behavior of two hybrid glass ionomer cements used as restorative materials (Variglass/Caulk Dentsply and Vitremer/3M was compared. Separate class II cavities were prepared on the mesial and distal aspects of thirteen extracted premolars. One restoration of each material was placed on every tooth. The cervical margins of the restorations were left one millimeter below the cementoenamel junction. Thermocycling was conduced in a 0.5% basic fuchsin solution. The teeth were washed and sectioned for microleakage analysis under a dissecting microscope. None of the materials tested were able to inhibit dye penetration at the cervical margin. Vitremer/3M was more effective than Variglass/Caulk Dentsply in reducing microleakage.

  12. MTA versus Portland cement: review of literature

    OpenAIRE

    Naiana Viana Viola; Mário Tanomaru Filho; Paulo Sérgio Cerri

    2011-01-01

    Introduction: Both Mineral Trioxide Aggregate (MTA) and Portland cement (PC) have been highlighted because of their favorable biological properties, with extensive applications in Endodontics, including the possibility of using into root canal filling. Objective: This article reviews literature related to MTA and PC comparing their physical, chemical and biological properties, as well as their indications. Literature review: Literature reports studies revealing the similarities between these ...

  13. Coprocessamento de CDR no processo de produção de cimento

    OpenAIRE

    Costa, João Miguel Bandeira

    2014-01-01

    A presente dissertação possui como objetivo avaliar o impacto e a viabilidade do coprocessamento de Combustíveis Derivados de Resíduos (CDR) no processo de produção de cimento, mais especificamente no Centro de Produção de Alhandra (CPA) da CIMPOR, quer a nível processual, quer a nível das emissões atmosféricas e da qualidade do produto final. O CDR é um dos combustíveis alternativos utilizados na indústria cimenteira, de modo a diminuir a dependência relativamente aos combustíveis fósseis...

  14. New method for analysis of portland cements with secondary components

    Directory of Open Access Journals (Sweden)

    Gomá, F.

    1986-03-01

    Full Text Available We describe a new method for the determination of the composition of Portland cement mixtures with active additions and the identification of the type of addition. This method enables us to classify a Portland cement or Portland with active additions, whatever this addition may be, and it is specially suitable for discriminating the type of slag when there are slags present.

    Se describe un nuevo método para determinar la composición de las mezclas de cemento Portland con adiciones activas e identificar el tipo de adición. Permite la clasificación de un cemento Portland o Portland con adiciones activas cualquiera que sea la adición y es especialmente indicado para discriminar el tipo de escoria cuando están presentes.

  15. 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

  16. Cimentos de fosfato de magnésio: consolidação e caracterização

    OpenAIRE

    Carvalho, Maria Arlete Carneiro Ribeiro de

    2013-01-01

    A reação entre o óxido de magnésio (MgO) e o fosfato de monoamónio (MAP), à temperatura ambiente, origina os cimentos de fosfato de magnésio, materiais caracterizados pela sua presa rápida e pelas excelentes propriedades mecânicas adquiridas precocemente. As propriedades finais são dependentes, essencialmente, da composição do cimento (razão molar magnésia:fosfato e utilização de retardantes de presa) mas também são influenciadas pela reatividade da magnésia utilizada. Neste trabalho, a...

  17. 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

  18. 75 FR 20523 - Regulated Navigation Areas; Port of Portland Terminal 4, Willamette River, Portland, OR

    Science.gov (United States)

    2010-04-20

    ..., Portland, OR'' in the Federal Register (74 FR 69047). We received one comment on the proposed rule. There... site. The RNAs will do so by prohibiting activities that could disturb or damage the engineered... viewing the docket, call Renee V. Wright, Program Manager, Docket Operations, telephone...

  19. A Portlander's View of Smart Growth

    OpenAIRE

    Randal O'Toole

    2004-01-01

    Metro, a regional planning authority, has written and implemented the nation's strongest and most comprehensive smart-growth plan in Portland, Oregon. For a region expected to grow in population by 80 percent in the next five decades, Metro's plan calls for a mere 6 percent expansion of land area; high-density housing in the form of apartments, mixed-use developments, and single-family homes on small lots; pedestrian-friendly design codes; 125 miles of rail transit; and almost no new highway ...

  20. MTA versus Portland cement: review of literature

    Directory of Open Access Journals (Sweden)

    Naiana Viana Viola

    2011-10-01

    Full Text Available Introduction: Both Mineral Trioxide Aggregate (MTA and Portland cement (PC have been highlighted because of their favorable biological properties, with extensive applications in Endodontics, including the possibility of using into root canal filling. Objective: This article reviews literature related to MTA and PC comparing their physical, chemical and biological properties, as well as their indications. Literature review: Literature reports studies revealing the similarities between these materials’ properties, including both biocompatibility and bone repair induction. Moreover, there is the need for the development of a root canal sealer based on these materials (MTA and PC. Conclusion: MTA and CP show promissory perspective both in Dentistry and Endodontics.

  1. 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

  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. Lithofacies and petrophysical properties of Portland Base Bed and Portland Whit Bed limestone as related to durability

    NARCIS (Netherlands)

    Dubelaar, C.W.; Engering, S.; Hees, R.P.J. van; Koch, R.; Lorenz, H.G.

    2003-01-01

    This study focuses on the differences in lithofacies and petrophysical properties of Base Bed and Whit Bed Portland limestone and the presumed relationships between these characteristics and the durability of this building stone. As Portland limestone probably will be used as a stone for several res

  4. Lithofacies and Petrophysical Properties of Portland Base Bed and Portland Whit Bed Limestone as Related to Durability

    NARCIS (Netherlands)

    Dubelaar, C.W.; Engering, S.; Van Hees, R.P.J.; Koch, R.; Lorenz, H.G.

    2003-01-01

    This study focuses on the differences in lithofacies and petrophysical properties of Base Bed and Whit Bed Portland limestone and the presumed relationships between these characteristics and the durability of this building stone. As Portland limestone probably will be used as a stone for several res

  5. 33 CFR 110.6 - Portland Harbor, Portland, Maine (between Little Diamond Island and Great Diamond Island).

    Science.gov (United States)

    2010-07-01

    ... (between Little Diamond Island and Great Diamond Island). 110.6 Section 110.6 Navigation and Navigable... Areas § 110.6 Portland Harbor, Portland, Maine (between Little Diamond Island and Great Diamond Island). Beginning at the southeasterly corner of the wharf, at the most southerly point of Great Diamond Island...

  6. 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

    OpenAIRE

    Marcos A. S. dos Anjos; Khosrow Ghavami; Normando P. Barbosa

    2003-01-01

    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 cilíndrico...

  7. 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

  8. 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

  9. In vitro evaluation of the marginal microleakage of amalgam restorations associated with dentin adhesive, glass ionomer cement and cavity varnish by means of different evaluation methods Avaliação in vitro da microinfiltração marginal em restaurações de amálgama associadas a adesivo dentinário, cimento de ionômero de vidro e verniz cavitário, utilizando diferentes métodos de avaliação

    Directory of Open Access Journals (Sweden)

    Adriano Tomio Hoshi

    2005-03-01

    Full Text Available This in vitro study evaluated the marginal microleakage of amalgam restorations associated with the cavity varnish Copalite - Cooley & Cooley (GI-CP, dentin adhesive OptiBond Solo - Kerr (GII-OS and the glass ionomer cement Vitremer - 3M (GIII-VT. Forty-five premolars were employed, which were submitted to independent class II preparations at the mesial and distal aspects comprising the marginal ridges and were restored with Dispersalloy - Dentsply. Afterwards, the teeth were thermocycled and stored in 0.5% basic fuchsine for 24 hours. The evaluations were conducted on a light microscope with 150x magnification and on the Sigma Scan software with employment of a single line and segmented lines. Data analysis allowed to establish that none of the materials was able to eliminate the marginal microleakage, having the GI - CP presented greater and statistically significant values in relation to the other groups in all evaluation methods (pEste trabalho avaliou, in vitro, a microinfiltração marginal de restaurações de amálgama associadas ao verniz cavitário Copalite - Cooley & Cooley (GI - CP, ao adesivo dentinário OptiBond Solo - Kerr (GII - OS e ao CIV Vitremer - 3M (GIII - VT. Foram utilizados 45 pré-molares que receberam preparos cavitários independentes classe II nas faces mesial e distal, envolvendo as cristas marginais. Todas as cavidades foram restauradas com a liga Dispersalloy - Dentsply. Posteriormente, os dentes sofreram termociclagem e foram armazenados em solução de fucsina básica a 0,5% por 24 horas. As avaliações foram realizadas através de um microscópio óptico com aumento de 150 vezes e no software Sigma Scan, utilizando linha única e linhas segmentadas. A análise dos dados obtidos permitiu constatar que nenhum dos materiais foi capaz de eliminar a microinfiltração marginal, sendo que o GI - CP apresentou valores maiores e estatisticamente significantes (p<0,05 em relação aos demais grupos em todos os m

  10. 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

  11. 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

  12. 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...

  13. Preterm delivery among people living around Portland cement plants.

    Science.gov (United States)

    Yang, Chun-Yuh; Chang, Chih-Ching; Tsai, Shang-Shyue; Chuang, Hung-Yi; Ho, Chi-Kung; Wu, Trong-Neng; Sung, Fung-Chang

    2003-05-01

    The Portland cement industry is the main source of particulate air pollution in Kaohsiung city. Data in this study concern outdoor air pollution and the health of individuals living in communities in close proximity to Portland cement plants. The prevalence of delivery of preterm birth infants was significantly higher in mothers living within 0-2 km of a Portland cement plant than in mothers living within 2-4 km. After controlling for several possible confounders (including maternal age, season, marital status, maternal education, and infant sex), the adjusted odds ratio was 1.30 (95% CI=1.09-1.54) for the delivery of preterm infants for mothers living close to the Portland cement plants, chosen at the start to be from 0 to 2 km. These data provide further support for the hypothesis that air pollution can affect the outcome of pregnancy. PMID:12706757

  14. Preterm delivery among people living around Portland cement plants

    International Nuclear Information System (INIS)

    The Portland cement industry is the main source of particulate air pollution in Kaohsiung city. Data in this study concern outdoor air pollution and the health of individuals living in communities in close proximity to Portland cement plants. The prevalence of delivery of preterm birth infants as significantly higher in mothers living within 0-2 km of a Portland cement plant than in mothers living within 2-4 km. After controlling for several possible confounders (including maternal age, season, marital status, maternal education, and infant sex), the adjusted odds ratio was 1.30 (95% I=1.09-1.54) for the delivery of preterm infants for mothers living close to he Portland cement plants, chosen at the start to be from 0 to 2 km. These data provide further support for the hypothesis that air pollution can affect he outcome of pregnancy

  15. 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,...

  16. 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,...

  17. 77 FR 26437 - Drawbridge Operation Regulation; Willamette River, Portland, OR

    Science.gov (United States)

    2012-05-04

    ... of Portland's Rock-n-Roll Half Marathon. This deviation allows the bridge to remain in the closed... facilitate safe, uninterrupted roadway passage of participants of the Rock-n-Roll Half Marathon event....

  18. 78 FR 21064 - Drawbridge Operation Regulations; Willamette River, Portland, OR

    Science.gov (United States)

    2013-04-09

    ... Portland's Rock-n-Roll Half Marathon. This deviation allows the bridge to remain in the closed position to... roadway passage of participants of the Rock-n-Roll Half Marathon event. The Hawthorne Bridge crosses...

  19. 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....

  20. 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.

  1. 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.

  2. Viabilidade técnica da fabricação de cimento com mistura de escória de aciaria LD e resíduo de granito Technical feasibility of fabrication of cement agglomerated with granite waste and BOF steel slag

    OpenAIRE

    Lúcio Flávio Arrivabene; Luiz Alberto Baptista Pinto Junior; José Roberto de Oliveira; Jorge Alberto Soares Tenório; Denise Crocce Romano Espinosa

    2012-01-01

    Esse trabalho estuda a viabilidade técnica da fabricação de cimento com uma mistura de resíduo proveniente da serragem de blocos de granito e escória de aciaria LD. Para isso, foi preparada uma mistura desses materiais de modo que a relação %CaO / %SiO2 fosse 1,2. Essa mistura foi fundida e resfriada rapidamente em água. A amostra foi caracterizada e o difratograma de raios X mostrou um material amorfo e a presença das fases mineralógicas Akermanita e Gehlenita, as quais são consideradas como...

  3. 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

  4. 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. PMID:25842101

  5. 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...

  6. 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...

  7. Anthropogenic carbon dioxide in the Portland metropolitan region

    Science.gov (United States)

    Rice, A. L.; Bostrom, G. A.; Brooks, M. K.; Hill, L.; Shandas, V.

    2011-12-01

    The Portland metropolitan region, located in the Columbia River Gorge, is the most populous region in Oregon. Greenhouse gas emissions inventories for Multnomah County (population ~710k) estimate 2008 emissions to be 8.5 million metric tons carbon dioxide equivalent, of which CO2 is the dominant source. These inventories suggest that County-wide greenhouse gas emissions are near 1990 levels, despite a 22% growth in population. This contrasts with US National greenhouse gas emissions, which are estimated to have grown ~14% since 1990. Despite this apparent progress, there has been no validation of either emissions inventories for the Portland metropolitan region or their trends in time. We present more than two years of measurements of CO2 at three stationary locations in the Portland metropolitan region: a downtown location on the campus of Portland State University; a residential site in southeast Portland; and a rural station on Sauvie Island, located ~30km northwest of Portland in the Columbia River Gorge. Beginning in July 2009, continuous measurements of CO2 at the sites show considerable variability due to global and regional CO2 sources, sinks and boundary layer meteorology. Here we focus on the enhancement of in-city concentrations above the rural Sauvie Island site (CO2 excess), a difference which averages ~6ppm during upgorge wind conditions. The southeast Portland residential site shows a significant enhancement of ~5ppm in CO2 concentration throughout the day. The downtown site shows a substantial diurnal cycle in CO2 excess with 10-15ppm higher values during the day and negative values for CO2 excess during the early morning hours, the cause of which is not well understood. Both in-city sites show an increase in CO2 excess centered around 7-8 am and 5-6 pm during the two rush-hour periods. To examine spatial variability, measurements of street-level CO2 concentrations were obtained using a mobile instrument mounted in a bike trailer during a summer

  8. Estudo de um ligante cimentício com baixo teor em clínquer

    OpenAIRE

    Luís, Raquel Filipa Cardoso Pereira

    2014-01-01

    Cada vez mais há uma preocupação acrescida no que diz respeito à diminuição da poluição e consequentemente com a proteção do meio ambiente, desta forma a presente dissertação dirige-se à necessidade de reduzir as emissões de CO2 no planeta. Neste sentido dá enfase os estudos relativos a ligantes cimentícios com menor teor de clínquer portland tornam-se mais pertinentes, dado que a produção deste componente do cimento faz-se com libertação significativa daquele gás. A possibilid...

  9. 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.

  10. 77 FR 29897 - Drawbridge Operation Regulation; Willamette River, Portland, OR

    Science.gov (United States)

    2012-05-21

    ... efficient movement of light rail and roadway traffic associated with the Rose Parade in Portland, Oregon... Steel Bridge remain closed to vessel traffic to facilitate safe efficient movement of light rail and... schedule of the lower deck which opens on signal. Vessels which do not require an opening of the upper...

  11. Análise do ciclo de vida do cimento. Caso de estudo: fábrica da Secil-Outão

    OpenAIRE

    Pato, Pedro Alexandre Melo de Oliveira

    2015-01-01

    O cimento é o material de construção mais utilizado na edificação de estruturas. A sua produção compreende um consumo material e energético muito significativo que se traduz numa contribuição igualmente relevante para a deterioração do ambiente. A presente dissertação consistiu na aplicação da abordagem de ciclo de vida ao processo de produção de dois tipos de cimento – CEM I 42,5 e CEM II 32,5 – com a finalidade de calcular o impacte ambiental de cada um e comprovar o desempenho ambiental...

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

    OpenAIRE

    Esmeralda Yoshico Arakaki Okino; Mário Rabelo de Souza; Marcos Antonio Eduardo Santana; Maria Eliete de Sousa; Divino Eterno Teixeira

    2004-01-01

    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, totaliza...

  13. 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

  14. Hábito e seletividade alimentar de pós-larvas de piavuçu, <em>Leporinus macrocephalusem> (Garavello & Britski, 1988), submetidas a diferentes dietas em cultivos experimentais Feeding habits of piavuçu post-larvae <em>Leporinus macrocephalusem> (Garavello & Britski, 1988), with different diets in trial tanks

    OpenAIRE

    Ricardo Pereira Ribeiro; Carmino Hayashi; Elias Nunes Martins; Leonardo Martin Nieto; Fábio Rosa Sussel

    2001-01-01

    Com o objetivo de conhecer alguns aspectos da dinâmica do hábito e seletividade alimentar de pós-larvas do piavuçu, Leporinus macrocephalus (Characiformes, Anostomidae) foi desenvolvido um experimento em 18 tanques de cimento amianto de 1m3, os quais foram previamente adubados de maneira uniforme e posteriormente povoados com 400 pós-larvas/tanque desta espécie. Foi esquematizado um delineamento inteiramente casualizado, com três tratamentos e seis repetições, e os dados foram analisados pelo...

  15. Cementing quality evaluation with ultrasonic logs in fiberglass casings; Avaliacao da qualidade do cimento em revestimentos de fibra de vidro

    Energy Technology Data Exchange (ETDEWEB)

    Campos, Wellington; Lazaro, Andre F. [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    2008-07-01

    The sonic and ultrasonic profiles are used as the main tools in assessing the cementing quality between formation and casing in oil wells. This assessment is important, because, if there is a failure in the primary cementing, both the structural integrity and zone isolation will be compromised. The sonic profiles are based on the acoustic energy attenuation in casing, cement and formation, while the ultrasonic profiles are based on the resonance of the wave pulse within the media where they travel (casings, cement and formation). The attenuation and resonance are due to the difference in the way the wave travel within these media. The acoustic impedance is the quantification of this difference, determining the refraction and reflection between the environments, and wave attenuation as well. In steel casings, this difference is meaningful, allowing the captured signals (reflected pulses) to be interpreted as good adhesion between cement and casing, or a lack of adhesion at some interval. In fiber glass casings, the impedance contrast between glass and cement is small and not detectable with the CBL/VDL sensors. The CBL/VDL tools provide an inefficient assessment of the quality of the cementing. The ultrasonic profile does not have this problem, theoretically. The goal of this work is to demonstrate and recommend the ultrasonic tool as the main instrument to assess the cementation quality in fiber glass casings. (author)

  16. Measurements of Carbon Dioxide in the Portland, Oregon Metropolitan Region

    Science.gov (United States)

    Bostrom, G. A.; Rice, A. L.

    2009-12-01

    Urban centers provide large sources of carbon dioxide (CO2) to the atmosphere through intensive use of fossil fuels. Due to a lack of federal regulatory framework in the United States, a patchwork of regional and statewide approaches to reducing CO2 emissions has emerged. The City of Portland together with Multnomah County established itself as an early frontier in this regard by creating greenhouse gas emissions inventories in 1990 and adopting a regional plan to reduce emissions in 1993. Most recent emissions inventories suggest that County-wide emissions of CO2 are near 1990 levels, despite a growing population, with an ambitious goal of reducing emissions 80% by 2050. However, there has been no validation of either emissions inventories or their trends in time. Here, we detail preliminary results of a study aimed at testing regional CO2 emissions inventories through measurements of CO2 concentrations and its 13C isotopic composition. In collaboration with Oregon Department of Environmental Quality three test sites were established: a downtown Portland location on the campus of Portland State University; a residential Southeast Portland location; and at Sauvie Island, located ~30km northwest (upwind, rural) of Portland in the Columbia River Gorge. Continuous measurements of summertime CO2 concentrations since late July, 2009 range from approximately 370ppm to 420ppm (±2.7σ) for downtown and residential sites, and 360ppm to 420ppm for Sauvie Island, while maximum outlier levels at all three sites exceed 480ppm. Measurements at all three sites show a marked diurnal cycle averaging 25-35ppm. Maximum CO2 concentrations typically occur 6-8 am and minimum concentrations 5-7 pm. The two dominant forcing mechanisms of this strong diurnal cycle are varying biological sources and sinks and the dynamics of the planetary boundary layer. There is also a significant enhancement of ~7ppm in the average measured concentrations at the two urban sites (~395ppm) compared with

  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

    Directory of Open Access Journals (Sweden)

    J. R. Garcia

    2007-03-01

    Full Text Available 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 compilados pode-se concluir que os aditivos retardadores agem geralmente de duas maneiras: 1 dificultando o processo de dissolução do cimento, por meio da formação de barreiras insolúveis ao redor das suas partículas e 2 favorecendo a formação de hidratos mais solúveis, o que aumenta o tempo necessário para que se inicie a precipitação. Por outro lado, os aditivos aceleradores de pega podem atuar favorecendo a formação de hidratos menos solúveis, diminuindo assim o tempo necessário para a precipitação ou ainda pela formação de núcleos iniciadores do processo de crescimento dos cristais dos hidratos. A análise destas informações leva a constatação de que a ação de alguns aditivos retardadores e aceleradores ocorre em estágios distintos no processo de hidratação do CAC. Portanto, pode-se imaginar uma situação onde a combinação desses dois aditivos poderia conferir um tempo de trabalhabilidade adequado e seguro, aliado a um curto tempo de desmoldagem.One of the main aspects for the development of refractories castables is to master the knowledge regarding calcium aluminate cement (CAC, as this binder is the most applied in these products. The objective of this work was to analyze the available information in the literature in order to explain the understanding regarding the actions of retarder and accelerator additives in the setting mechanisms of CACs. The analysis of the compiled information pointed out that the

  18. Portland cement conditioning of the oil radioactive wastes

    International Nuclear Information System (INIS)

    Cementation is a widely used method to immobilize radioactive wastes generated during the operation of nuclear power plants. The oily radioactive wastes resulting during the normal service of Nuclear Power Plant at Cernavoda, Romania, can be conditioned in Portland cement as emulsions. In this way the interaction with cement water is not blocked. For this purpose, four compositions for conditioning were studied, namely: i) cement-emulsion; ii) cement-emulsion-sodium silicate; iii) cement-emulsion-sodium silicate-lime; iv) cement-emulsion-sand. The apparent density of hardened binding mixtures, setting time, compressive strength of hardened samples, leaching rate of tritium were determined. The results have shown that the oily wastes can be conditioned in a good manner when using Portland cement, emulsion conditioners, sodium silicate and lime. (authors)

  19. 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.

  20. Use of red mud as addition for portland cement mortars

    International Nuclear Information System (INIS)

    The aim of the present research work was to investigate the possibility of adding red mud, an alkaline leaching waste that is obtained from bauxite during the Bayer process for alumina production, in the raw meal of Portland cement mortars. The red mud is classified as dangerous, according to NBR 10004/2004, and world while generation reached over 117 million tons/year. This huge production requires high consuming products to be used as incorporation matrix and we studied the influence of red mud addition on the characteristics of cement mortars and concrete. In this paper the properties of Portland cement mortars incorporating high amounts of red mud was evaluated: pH variation, fresh (setting time, workability or normal consistency and water retention), and hardened state (mechanical strength, capillary water absorption, density and apparent porosity). Results seem promising for red mud additions up to 20 wt%. (author)

  1. 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

  2. THE INFLUENCE OF ORTHOPHOSPHATES ON THE PROPERTIES OF PORTLAND CEMENT

    OpenAIRE

    Antanas Kaziliunas

    2014-01-01

    The article continues the research of input reduction of phosphogypsum preparation for the production of building materials. Desiccated apatite (2.18 % P2O5 in gypsum) makes the least changes in the properties of Portland cement: it prolongs the cement setting times and reduces the compressive strength about 10 %. The apatite formation in the pastes of soluble orthophosphate-cement occurs during the formation of X-ray amorphous colloidal calcium orthophosphate hydrate, which prolo...

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

    OpenAIRE

    Pangdaeng, S.; Sata, V.; Aguiar, J. L. Barroso de; Torgal, Fernando Pacheco; Chindaprasirt, P.

    2015-01-01

    In this study, calcined kaolin–white Portland cement geopolymerwas investigated for use as biomaterial. Sodiumhydroxide 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 co...

  4. The African American Wellness Village in Portland, Ore

    OpenAIRE

    McKeever, Corliss; Koroloff, Nancy; Faddis, Collaine

    2006-01-01

    More than 80% of African Americans in Oregon reside in the Portland metropolitan area; African Americans comprise 1.7% of the state's population. Although relatively small, the African American population in the state experiences substantial health disparities. The African American Health Coalition, Inc was developed to implement initiatives that would reduce these disparities and to promote increased communication and trust between the African American community and local institutions and or...

  5. Injectable citrate-modified Portland cement for use in vertebroplasty

    OpenAIRE

    Wynn-Jones, Gareth; Shelton, Richard M.; Hofmann, Michael P

    2014-01-01

    The injectability of Portland cement (PC) with several citrate additives was investigated for use in clinical applications such as vertebroplasty (stabilization of a fractured vertebra with bone cement) using a syringe. A 2-wt % addition of sodium or potassium citrate with PC significantly improved cement injectability, decreased cement setting times from over 2 h to below 25 min, while increasing the compressive strength to a maximum of 125 MPa. Zeta-potential measurements indicated that the...

  6. Utilization of gold tailings as an additive in Portland cement.

    Science.gov (United States)

    Celik, Ozlem; Elbeyli, Iffet Yakar; Piskin, Sabriye

    2006-06-01

    Mine tailings are formed as an industrial waste during coal and ore mining and processing. In the investigated process, following the extraction of gold from the ore, the remaining tailings are subjected to a two-stage chemical treatment in order to destroy the free cyanide and to stabilize and coagulate heavy metals prior to discharge into the tailings pond. The aim of this study was the investigation of the feasibility of utilization of the tailings as an additive material in Portland cement production. For this purpose, the effects of the tailings on the compressive strength properties of the ordinary Portland cement were investigated. Chemical and physical properties, mineralogical composition, particle size distribution and microstructure of the tailings were determined by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), particle size analyzer (Mastersizer) and scanning electron microscope (SEM). Following the characterization of the tailings, cement mortars were prepared by intergrinding Portland cement with dried tailings. Composition of the cement clinkers were adjusted to contain 5, 15, 25% (wt/wt) dried tailings and also silica fume and fly ash samples (C and F type) were added to clinker in different ratios. The mortars produced with different amounts of tailings, silica fume, fly ashes and also mixtures of them were tested for compressive strength values after 2, 7, 28 and 56 days according to the European Standard (EN 196-1). The results indicated that gold tailings up to 25% in clinker could be beneficially used as an additive in Portland cement production. It is suggested that the gold tailings used in the cement are blended with silica fume and C-type fly ash to obtain higher compressive strength values. PMID:16784164

  7. 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

  8. Avaliação da atividade pozolânica dos resíduos de cerâmica vermelha produzidos nos principais polos ceramistas do Estado de S. Paulo

    OpenAIRE

    Garcia, E.; M. Cabral Junior; V. A. Quarcioni; F. F. Chotoli

    2015-01-01

    Com intuito de se obter vantagens técnicas, econômicas e ambientais, vem se acentuando o interesse da indústria do cimento para adições minerais em substituição parcial ao clínquer no cimento Portland. Uma das adições minerais mais comuns e que vem ganhando espaço no mercado brasileiro corresponde à argila calcinada, que agrega basicamente as características de pozolanicidade aos seus produtos compostos. Um material com propriedades potencialmente similares às argilas calcinadas e ainda não a...

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

    OpenAIRE

    Marcos Felipe Marcatto de Abreu; Riccardo Gomes Gobbi; Maurício Rodrigues Zenaide; Gustavo Constantino de Campos; César Augusto Martins Pereira; José Ricardo Pécora; Gilberto Luis Camanho

    2009-01-01

    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,...

  10. 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

  11. 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

  12. Low porosity portland cement pastes based on furan polymers

    International Nuclear Information System (INIS)

    The effect of three different types of Furan polymers on the porosity, mechanical properties, mechanism of hydration and microstructure of Ordinary Portland cement (OPC) pastes was investigated. The results showed that mixing the OPC with Furan polymers, the standard water of consistency of the different cement pastes decreases and therefore the setting times (initial and final) are shortened. The total porosity of the hardened cement pastes decreased, while the mechanical properties improved and enhanced at all curing ages of hydration compared with those of the pure OPC pastes. The hydration process with Furan polymers proceeded according to the following decreasing order: F.ac. > F.ph. > F.alc. > OPC

  13. Synthesis report: D-cracking in portland cement concrete pavements

    Science.gov (United States)

    Thompson, S. R.; Olsen, M. P. J.; Dempsey, B. J.

    1980-06-01

    The mechanisms and testing procedures for D-cracking in portland cement concrete pavements are examined. Benefication procedures are also investigated. The three general responses to freezing in the aggregate/paste system include elastic accommodation, high internal pressure, and high external pressure. It is found that the critical aggregate parameters influencing D-cracking are degree of saturation, maximum particle size, permeability, porosity, and pore size distribution. Evaluation of present laboratory testing procedures indicated that the ASTM C666, VPI slow-cool, Mercury Porosimetry, and Iowa Pore Index Tests correlated the best with field performance of concrete with respect to D-cracking.

  14. Symptoms, ventilatory function, and environmental exposures in Portland cement workers.

    OpenAIRE

    Abrons, H L; Petersen, M R; Sanderson, W T; Engelberg, A L; Harber, P

    1988-01-01

    Data on respiratory symptoms and pulmonary function were obtained for 2736 Portland cement plant workers and 755 controls. Personal dust samples contained a geometric mean concentration of 0.57 mg/m3 for respirable dust and 2.90 mg/m3 for total dust. Cement workers and controls had similar prevalences of symptoms, except that 5.4% of the cement workers had dyspnoea compared with 2.7% of the controls. The mean pulmonary function indices were similar for the two groups. Among cement plant worke...

  15. 75 FR 54969 - National Emission Standards for Hazardous Air Pollutants From the Portland Cement Manufacturing...

    Science.gov (United States)

    2010-09-09

    ..., 1998; see also 63 FR at 14193 (March 24, 1998) (area source cement kilns' emissions of mercury, dibenzo... NESHAP on May 6, 2009. See 74 FR 21136. We received a total of 3,229 comments from the Portland cement... v. EPA Litigation On June 14, 1999 (64 FR 31898), EPA issued the NESHAP for the Portland...

  16. Differentiating seawater and groundwater sulfate attack in Portland cement mortars

    International Nuclear Information System (INIS)

    The study reported in this article deals with understanding the physical, chemical and microstructural differences in sulfate attack from seawater and groundwater. Portland cement mortars were completely immersed in solutions of seawater and groundwater. Physical properties such as length, mass, and compressive strength were monitored periodically. Thermal analysis was used to study the relative amounts of phases such as ettringite, gypsum, and calcium hydroxide, and microstructural studies were conducted by scanning electron microscopy. Portland cement mortars performed better in seawater solution compared to groundwater solution. The difference in performance could be attributed to the reduction in the quantity of the expansive attack products (gypsum and ettringite). The high Cl concentration of seawater could have played an important role by binding the C3A to form chloroaluminate compounds, such as Friedel's salt (detected in the microstructural studies), and also by lowering the expansive potential of ettringite. Furthermore, the thicker layer of brucite forming on the specimens in seawater could have afforded better protection against ingress of the solution than in groundwater

  17. Portland's experience with land use tools to promote green roofs

    International Nuclear Information System (INIS)

    In the late 1990s, the City of Portland, Oregon faced environmental challenges that prompted the City to mandate environmentally sensitive development. Several programs were developed in response to these challenges, some of which resulted in the creation of land use policies and incentives that promote green roofs. Zoning code provisions were adopted in 2001 to promote eco-roofs in an effort to reduce stormwater runoff, mitigate urban heat island effects, provide habitat for birds, and improve air quality and energy efficiency. The Central City Fundamental Design Guidelines were also revised to encourage eco-roof development. In 2002, the South Waterfront Plan was created to integrate ecological design into an urban environment through sustainability principles and practices. Land use tools were developed to introduce developers to an approach that reduced energy costs and stormwater costs, while also contributing to a project's marketability. These tools were created with the support of programs and policies such as the CSO (Combined Sewer Overflow) Program; eco-roof research which began in 1995 to determine the stormwater management potential of eco-Green roofs; technical assistance to encourage and highlight sustainable development practices; the Stormwater Management Manual that set standards for the amount and quality of stormwater runoff leaving development sites; the G/Rated Program that offers resources for green building practices; the Green Investment Fund that supports the G/Rated Program; and, the Portland Development Commission Green Building Policy financing tool for earth-friendly designs and materials. 34 refs., 2 figs

  18. 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

  19. In vitro study of the effect of Er: YAG laser irradiation on the apical sealing of different root canal sealers Estudo "in vitro" do efeito da irradiação do laser Er: YAG no selamento apical de diferentes tipos de cimentos obturadores

    Directory of Open Access Journals (Sweden)

    Fernanda Vieira Medina

    2006-08-01

    Full Text Available OBJECTIVES: The aim of this study was to determine the effect of Er:YAG laser irradiation used to clean dentinal walls on the apical sealing of root canals filled with different types of sealers. Background Data: Laser application to the dentinal walls removed debris, rendering the root canals free of smear layers and leaving the dentinal canaliculi open. METHODS: Sixty-four maxillary canines obtained from laboratory files were instrumented with K-files (Dentsply, Maillefer, Ballaigues, Switzerland using the crown-down technique, and irrigated with a 0.5% sodium hypochlorite solution. The specimens were divided into two groups of 32 teeth each. In group I, the teeth were instrumented and irrigated with sodium hypochlorite solution, and divided into four subgroups to be sealed with the different materials (Endofill, N-Rickert, Sealapex and Sealer 26. In group II, the root canals were subjected to Er:YAG laser irradiation (200 mJ, 7 Hz and 60 J total energy, followed by root canal sealing as in group I. RESULTS: The data showed lower levels of apical microleakage in the teeth filled with N-Rickert, Sealapex and Sealer 26 cements than in those sealed with Endofill (p 0.05. CONCLUSIONS: The Er:YAG laser irradiation applied to the root canal walls was not able to prevent apical microleakage.OBJETIVOS: Avaliou-se a infiltração marginal apical em caninos superiores, obturados com quatro tipos diferentes de cimento, os quais foram imersos em tinta nanquim e mantidos a uma temperatura de 37º C por 96 horas, descalcificados em solução de ácido clorídrico a 5%, desidratados em série crescente de álcoois e diafanizados em salicilato de metila. MÉTODOS: Para isto, 64 dentes de estoque foram instrumentados pela técnica "crown-down", irrigados com solução de hipoclorito de sódio a 0,5% e divididos em dois grupos experimentais. Os dentes do Grupo I foram subdivididos em quatro sub-grupos de oito elementos e obturados cada um deles com os cimentos

  20. 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.

  1. Cement for oil well developed from ordinary cement: characterization physical, chemical and mineralogical; Cimento para poco de petroleo desenvolvido a partir de cimento comum: caracterizacao fisica, quimica e mineralogica

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, D.N.S.; Neves, G. de A.; Chaves, A.C.; Mendonca, A.M.G.D.; Lima, M.S. de [Universidade Federal de Campina Grande (UFCG), PB (Brazil); Bezerra, U.T., E-mail: daninascimento.eng@gmail.com [Instituto Federal de Educacao, Ciencia e Tecnologia da Paraiba (IFPB), Campina Grande, PB (Brazil)

    2012-07-01

    This work aims to characterize a new type of cement produced from the mixture of ordinary Portland cement, which can be used as an option in the cementing of oil wells. To enable this work we used the method of lineal programming for the new cement composition, then conducted tests to characterize through particle size analysis by laser diffraction, chemical analysis by EDX, TGA, X-ray diffraction, time grip, resistance to compression. The overall result showed that the new cement had made low-C3A, takes more time to the CPP, thermal stability up to 500 ° C, the kinetics of hydration and low levels of major components consistent with the specifications of ABNT. (author)

  2. Physical evaluation of a new pulp capping material developed from portland cement

    Science.gov (United States)

    Negm, Ahmed; Hassanien, Ehab; Abu-Seida, Ashraf

    2016-01-01

    Background This study examined the effects of addition of 10% and 25% by weight calcium hydroxide on the physicochemical properties of Portland cement associated with 20% bismuth oxide in order to develop a new pulp capping material. Material and Methods The solubility, pH value, setting time, compressive strength, and push out bond strength of modified Portland were evaluated and compared to those of mineral trioxide aggregate (MTA) and Portland cement containing 20% bismuth oxide. Results The statistical analysis was performed with ANOVA and Duncan’s post-hoc test. The results show that the strength properties and push out bond strength of Portland cement were adversely affected by addition of calcium hydroxide especially with a ratio of 25 wt%, however, the setting time and pH were not affected. MTA showed a statistically significant lower setting time than other cements (P≤0.001). Portland cement with bismuth oxide and Port Cal I showed a statistically significant higher Push out Bond strength than MTA and Port Cal II (P=0.001). Conclusions Taking the setting time, push out bond strength and pH value into account, addition of 10 wt% calcium hydroxide to Portland cement associated with 20% bismuth oxide produces a new pulp capping material with acceptable physical and adhesive properties. Further studies are recommended to test this cement biologically as a new pulp capping material. Key words:Calcium hydroxide, MTA, Portland cement, setting time, solubility, strength. PMID:27398178

  3. 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.

  4. 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.

  5. Hydration of Portland cement with additions of calcium sulfoaluminates

    International Nuclear Information System (INIS)

    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.

  6. Early hydration of portland cement with crystalline mineral additions

    International Nuclear Information System (INIS)

    This research presents the effects of finely divided crystalline mineral additions (quartz and limestone), commonly known as filler, on the early hydration of portland cements with very different mineralogical composition. The used techniques to study the early hydration of blended cements were conduction calorimeter, hydraulicity (Fratini's test), non-evaporable water and X-ray diffraction. Results showed that the stimulation and the dilution effects increase when the percentage of crystalline mineral additions used is increased. Depending on the replacement proportion, the mineralogical cement composition and the type of crystalline addition, at 2 days, the prevalence of the dilution effect or the stimulation effect shows that crystalline mineral additions could act as sites of heat dissipation or heat stimulation, respectively

  7. 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

  8. Aspectos do coprocessamento de resíduos em fornos de clínquer Aspects of waste co-processing in clinker kilns

    OpenAIRE

    Sônia Denise Ferreira Rocha; Vanessa de Freitas Cunha Lins; Belinazir Costa do Espírito Santo

    2011-01-01

    A prática do coprocessamento de resíduos na indústria de cimento tem se expandido devido à necessidade crescente de uma destinação ambiental e socialmente mais adequada de resíduos perigosos provenientes de diversos processos industriais. O objetivo deste trabalho foi realizar uma revisão sobre o coprocessamento de resíduos em fornos de clínquer, no Brasil e no mundo, visando contribuir para a otimização dos processos, identificando os aspectos já estudados e os que ainda demandam pesquisas. ...

  9. 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...

  10. 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)...

  11. 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...

  12. 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.

  13. 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...

  14. 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

  15. Utilization of Iron Ore Tailings as Raw Material for Portland Cement Clinker Production

    OpenAIRE

    Li Luo; Yimin Zhang; Shenxu Bao; Tiejun Chen

    2016-01-01

    The cement industry has for some time been seeking alternative raw material for the Portland cement clinker production. The aim of this research was to investigate the possibility of utilizing iron ore tailings (IOT) to replace clay as alumina-silicate raw material for the production of Portland cement clinker. For this purpose, two kinds of clinkers were prepared: one was prepared by IOT; the other was prepared by clay as a reference. The reactivity and burnability of raw meal, mineralogical...

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

    OpenAIRE

    Chenchen Gong; Jibao Xin; Shoude Wang; Lingchao Lu

    2016-01-01

    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 ...

  17. The comparison between sulfate salt weathering of portland cement paste and calcium sulfoaluminate cement paste

    OpenAIRE

    Liu, Zanqun; Deng, Dehua; De Schutter, Geert

    2015-01-01

    In this paper, the damage performances of sulfate salt weathering of Portland cement paste and calcium sulfoaluminate (CSA) cement paste were compared according to authors' previous studies. It was found that the evaporation zone of speciments partially immersed in 10% Na2SO4 solution were both severely deteriorated for Portland cement and CSA cement. However, the differences were more significant: (1) the CSA cement paste were damaged just after 7 days exposure compared to the 5 months expos...

  18. How Do Social Service Providers View Recent Immigrants? Perspectives from Portland, Maine, and Olympia, Washington

    OpenAIRE

    CLEVENGER, CASEY; DERR, AMELIA SERAPHIA; Cadge, Wendy; CURRAN, SARA

    2014-01-01

    This article explores how social service providers in two small, geographically distinct cities—Portland, Maine, and Olympia, Washington—understand the importance of welcoming and incorporating new immigrants in their cities. We focus on how providers characterize their responsibilities, how they understand the importance of responding to new immigrants, and what they describe as the challenges and opportunities presented by recent immigration to their cities. Despite differences in Portland ...

  19. 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.

  20. Comparação das propriedades de sorção e solubilidade de cimentos submetidos a diferentes soluções e tempos de armazenagem Comparison of sorption and solubility properties of cements submitted to different solutions and storage times

    Directory of Open Access Journals (Sweden)

    Priscilla do M. R. Busato

    2012-01-01

    Full Text Available A finalidade deste estudo foi avaliar in vitro algumas propriedades dos cimentos Rely X U100 (3M ESPE, Rely X Luting (3M ESPE e All Cem (FGM, como a sorção e solubilidade em água destilada e numa solução de álcool 75%, por períodos de 7 e 15 dias. Foram confeccionados 60 corpos-de-prova, divididos em três grupos (n = 20, de acordo com o cimento escolhido. Eles foram então divididos em quatro grupos de acordo com os fatores avaliados, tipo de solução e período de avaliação. Os espécimes foram padronizados com 8 mm de diâmetro e 1 mm de espessura, sendo polimerizados sobre lâminas de microscopia e matriz de poliéster e os excessos foram removidos com lâmina de bisturi. As amostras foram transferidas para uma estufa a 37 °C até atingir a massa constante, denominada M1. Na sequência, foram imersas em suas respectivas soluções e permaneceram armazenadas por 7 e 15 dias. Decorrido este período, os espécimes foram pesados novamente, obtendo-se a M2. Para obter a nova massa constante, denominada M3, os mesmos retornaram à estufa a 37 °C. Para o cálculo da sorção e da solubilidade, foram utilizadas equações, sendo (M2-M3/V e (M1-M3/V, respectivamente. Os resultados foram submetidos à ANOVA de dois fatores.The aim of this study was to evaluate in vitro some properties of the resin cement Rely X U100 (3M ESPE, such as the sorption and solubility in water and a solution of alcohol 75% for periods of 7 and 15 days. The 60 samples were divided into three groups according to the cement used, and then divided into four groups according to the factors evaluated, type of solution and evaluation period. The samples were standardized with 8 mm diameter and 1 mm in thickness and light cured in polyester matrix, with the excess being removed with a scalpel blade. The samples were transferred to a greenhouse at 37 °C until reaching constant mass, referred to as M1. The samples were then immersed in solutions and stored for 7 and 15

  1. Superplasticized Portland cement: Production and compressive strength of mortars and concrete

    Energy Technology Data Exchange (ETDEWEB)

    Bouzoubaa, N.; Zhang, M.H.; Malhotra, V.M. [Natural Resources Canada, Ottawa, Ontario (Canada)

    1998-12-01

    This paper deals with the effect of intergrinding different percentages of a naphthalene-based superplasticizer with Portland cement clinker and gypsum on the fineness of the product, and on the water requirement and the compressive strength of the mortars made with the superplasticized cement. The properties of the fresh and hardened concrete made with the superplasticized cements were also investigated. The results showed that the intergrinding of a given amount of a naphthalene-based superplasticizer with Portland clinker and gypsum reduced the grinding time required for obtaining the same Blaine fineness as that of the control Portland cement without the superplasticizer. The water requirement of the mortars made with the superplasticized cements was similar to that of the mortars made with the control Portland cements when the same amount of the superplasticizer was added at the mortar mixer; for a given grinding time and a Blaine fineness of {approximately}4500 cm{sup 2}/g, the mortars made with the superplasticized cement had higher compressive strength than those made with the control Portland cement. For a given grinding time or Blaine fineness of cement {ge}5000 cm{sup 2}/g, the slump loss, air content stability, bleeding, autogenous temperature rise, setting times, and compressive strength of the concrete made with the superplasticized cements were generally comparable to those of the concrete made with the control Portland cements when the superplasticizer was added at the concrete mixer.

  2. 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

  3. 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.

  4. Hydrolitical equilibrium of hydrates of portland cement, part 1

    International Nuclear Information System (INIS)

    Based on the basic principles of thermodynamics the present report (Part 1) provides a contribution to thermodynamically favoured stable states of the most important hydrated compounds of portland cement. An extensive literature search was made to find the related thermodynamic data for the data-base. According to our calculations even at room temperature the C-S-H-Gel is not the thermodynamically most stable end product of hydrated calcium silicates. The most stable products might be Hillebrandit, Foshagit, 11A Tobermorit or Gyrolit. It is generally agreed, that the cubic hydrate C3AH6 is the stable end product of calcium aluminate hydrates. Our calculations lead to the same results. By sulfates we have found, that at lower temperatures Ettringit is the stable phase, but at higher temperatures the corresponding monosulfate is more stable. Ettringit is not stable relative to C3AH6 even in its water solutions. Ettringit is also not stable relative to Friedl's salt. More information could be found in Part 2 of this report (in preparation). 46 figs., 13 refs., 18 tabs. (Authors)

  5. Estimated longevity of performance of Portland cement grout seal materials

    International Nuclear Information System (INIS)

    The sealing of boreholes, fractures and underground workings of repositories is a common concern for all programs investigating the deep burial of nuclear waste as a disposal mechanism. Two grouting materials, bentonite and portland cement, have been identified by many programs as likely candidate seal materials. The longevity of performance of both of these materials is currently being investigated under the auspices of the Stripa Project. These investigations comprise coordinated laboratory, field and modeling studies to produce fundamental data, practical experience and estimates of long-range performance, respectively. Long-term performance is an especially sensitive issue for cement because the phases that comprise cement are metastable. Accordingly, it may be assumed that cement grout performance will degrade with time. For a simplified cement system, two mechanisms for chemical degradation have been considered: phase change and dissolution. When considering dissolution, both equilibrium (slow flow) and open (fast flow) systems have been analyzed to establish bounds. Granitic terrain groundwaters ranging from fresh to saline have been taken as solvents. To assess the consequences in terms of flow, an empirical relation between cement permeability and porosity has been developed. Predictions of performance changes with time have been produced by making conservative estimates of local hydraulic head conditions for various periods of repository history. For the crystalline rock environments considered, preliminary results indicate that cement grout performance may be acceptable for tens of thousands to millions of years providing its initial hydraulic conductivity is on the order of 10-12 m/s

  6. Injectable citrate-modified Portland cement for use in vertebroplasty.

    Science.gov (United States)

    Wynn-Jones, Gareth; Shelton, Richard M; Hofmann, Michael P

    2014-11-01

    The injectability of Portland cement (PC) with several citrate additives was investigated for use in clinical applications such as vertebroplasty (stabilization of a fractured vertebra with bone cement) using a syringe. A 2-wt % addition of sodium or potassium citrate with PC significantly improved cement injectability, decreased cement setting times from over 2 h to below 25 min, while increasing the compressive strength to a maximum of 125 MPa. Zeta-potential measurements indicated that the citrate anion was binding to one or more of the positively charged species causing charged repulsion between cement particles which dispersed aggregates and caused the liquefying effect of the anion. Analysis of the hydrating phases of PC indicated that the early strength producing PC phase (ettringite) developed within the first 2 h of setting following addition of the citrate anion, while this did not occur in the control cement (PC only). Within 24 h ettringite developed in PC as well as calcium-silicate-hydrate (C-S-H), the major setting phase of PC, whereas cements containing citrate did not develop this phase. The evidence suggested that in the presence of citrate the cements limited water supply appeared to be utilized for ettringite formation, producing the early strength of the citrate cements. The present study has demonstrated that it is possible to modify PC with citrate to both improve the injectability and crucially reduce the setting times of PC while improving the strength of the cement. PMID:24711245

  7. In situ hydration of Portland cement monitored by neutron diffraction

    Science.gov (United States)

    Castellote, M.; Alonso, C.; Andrade, C.; Campo, J.; Turrillas, X.

    Ordinary Portland cement was mixed with deuterium oxide with a heavy water/cement ratio of 0.6 to monitor the in situ hydration, while acquiring diffraction patterns every 2.5min. Two different experiments were carried out under different heating conditions. In one case, the temperature was uniformly raised from room temperature to 98 °C at a heating rate of 20 °C/h. In the second case, the heating was performed from 32 °C to 100 °C at a slower rate: 12 °C/h. The disappearance and appearance of relevant anhydrous and hydrated phases were monitored and quantified by fitting isolated diffraction peaks to Gaussians. Ca3SiO5 dissolved completely during the experiment and Ca2SiO4 only partially disappeared. Ca(OD)2 precipitated and its growth rate exhibited a sigmoidal shape. Ettringite and hillebrandite formed but then dissolved before the end of the experiments. At the end only Ca(OD)2 and some Ca2SiO4 remained as crystalline phases.

  8. 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.

  9. Optimization of calcium chloride content on bioactivity and mechanical properties of white Portland cement

    International Nuclear Information System (INIS)

    This research investigates the optimization of calcium chloride content on the bioactivity and mechanical properties of white Portland cement. Calcium chloride was used as an addition of White Portland cement at 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10% by weight. Calcium chloride was dissolved in sterile distilled water and blended with White Portland cement using a water to cement ratio of 0.5. Analysis of the bioactivity and pH of white Portland cement pastes with calcium chloride added at various amounts was carried out in simulated body fluid. Setting time, density, compressive strength and volume of permeable voids were also investigated. The characteristics of cement pastes were examined by X-ray diffractometer and scanning electron microscope linked to an energy-dispersive X-ray analyzer. The result indicated that the addition of calcium chloride could accelerate the hydration of white Portland cement, resulting in a decrease in setting time and an increase in early strength of the pastes. The compressive strength of all cement pastes with added calcium chloride was higher than that of the pure cement paste, and the addition of calcium chloride at 8 wt.% led to achieving the highest strength. Furthermore, white Portland cement pastes both with and without calcium chloride showed well-established bioactivity with respect to the formation of a hydroxyapatite layer on the material within 7 days following immersion in simulated body fluid; white Portland cement paste with added 3%CaCl2 exhibited the best bioactivity. - Highlights: ► Optimization CaCl2 content on the bioactivity and mechanical properties. ► CaCl2 was used as an addition at 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10% by weight. ► CaCl2 resulted in a decrease in setting time and an increase in early strength. ► Addition of 3%CaCl2 exhibited the optimum formation of hydroxyapatite.

  10. 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.

  11. 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.

  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. Utilization of Iron Ore Tailings as Raw Material for Portland Cement Clinker Production

    Directory of Open Access Journals (Sweden)

    Li Luo

    2016-01-01

    Full Text Available The cement industry has for some time been seeking alternative raw material for the Portland cement clinker production. The aim of this research was to investigate the possibility of utilizing iron ore tailings (IOT to replace clay as alumina-silicate raw material for the production of Portland cement clinker. For this purpose, two kinds of clinkers were prepared: one was prepared by IOT; the other was prepared by clay as a reference. The reactivity and burnability of raw meal, mineralogical composition and physical properties of clinker, and hydration characteristic of cement were studied by burnability analysis, differential thermal analysis, X-ray diffraction, and hydration analysis. The results showed that the raw meal containing IOT had higher reactivity and burnability than the raw meal containing clay, and the use of IOT did not affect the formation of characteristic mineralogical phases of Portland cement clinker. Furthermore, the physical and mechanical performance of two cement clinkers were similar. In addition, the use of IOT was found to improve the grindability of clinker and lower the hydration heat of Portland cement. These findings suggest that IOT can replace the clay as alumina-silicate raw material for the preparation of Portland cement clinker.

  14. Compósito de colágeno com silicato e hidroxiapatita como material para endodontia: preparação e caracterização = Collagen composite with silicate and hydroxyapatite as endodontic material: preparation and characterization

    OpenAIRE

    E'Gues, Miguel Antônio Menezes; Paula, Márcio de; Goissis, Gilberto

    2008-01-01

    Objetivo: Este trabalho teve por objetivo preparar e caracterizar um novo compósito de colágeno com silicato e hidroxiapatita que possa vir a ser utilizado como material endodôntico em capeamento pulpar direto e em pulpotomia. Metodologia: Os materiais utilizados como matéria-prima foram colágeno do tipo I na forma aniônica, silicato (cimento Portland Branco) e hidroxiapatita sintetizada. Estes materiais foram misturados em proporções variadas de modo a obter um material compósito na forma de...

  15. Interfacial morphology and domain configurations in 0-3 PZT-Portland cement composites

    International Nuclear Information System (INIS)

    Cement-based piezoelectric composites have attracted great attention recently due to their promising applications as sensors in smart structures. Lead zirconate titanate (PZT) and Portland cement (PC) composite were fabricated using 60% of PZT by volume. Scanning Electron Microscope and piezoresponse force microscope were used to investigate the morphology and domain configurations at the interfacial zone of PZT-Portland cement composites. Angular PZT ceramic grains were found to bind well with the cement matrix. The submicro-scale domains were clearly observed by piezoresponse force microscope at the interfacial regions between the piezoelectric PZT phase and Portland cement phase, and are clearer than the images obtained for pure PZT. This is thought to be due to the applied internal stress of cement to the PZT ceramic particle which resulted to clearer images.

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

    International Nuclear Information System (INIS)

    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.%

  17. 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.%.

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

    DEFF Research Database (Denmark)

    Moesgaard, M; Poulsen, Søren Lundsted; Herfort, D; Steenberg, M; Kirkegaard, L F; Skibsted, Jørgen; Yue, Y

    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)....

  19. 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.......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....

  20. Multi-scale simulation of capillary pores and gel pores in Portland cement paste

    OpenAIRE

    Gao, Peng; YE, guang; Wei, Jiangxiong; Yu, Qijun

    2015-01-01

    The microstructures of Portland cement paste (water to cement ratio is 0.4, curing time is from 1 day to 28 days) are simulated based on the numerical cement hydration model, HUMOSTRUC3D (van Breugel, 1991; Koenders, 1997; Ye, 2003). The nanostructures of inner and outer C-S-H are simulated by the packing of monosized (5 nm) spheres. The pore structures (capillary pores and gel pores) of Portland cement paste are established by upgrading the simulated nanostructures of C-S-H to th...

  1. Four Decades of Systems Science Teaching and Research in the USA at Portland State University

    Directory of Open Access Journals (Sweden)

    Wayne Wakeland

    2014-04-01

    Full Text Available Systems science is defined in general fashion, and a brief background is provided that lists some of the systems science-related societies, conferences, journals, research institutes, and educational programs. The Systems Science Graduate Program at Portland State University in Portland, OR, USA, is described in detail, including its history, curriculum, students, faculty, and degrees granted. Dissertation topics are summarized via word diagrams created from dissertation titles over the years. MS degrees, student placement, and undergraduate courses are also mentioned, and future plans for the program are described including its support for sustainability education.

  2. 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.

  3. 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

  4. 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

  5. Determinação espectrofotométrica de cloreto em cimento após preparo de amostra por piroidrólise

    Directory of Open Access Journals (Sweden)

    Fabio A. Duarte

    2013-01-01

    Full Text Available A method based on pyrohydrolysis was proposed for cement sample preparation and further chloride determination by spectrophotometry using flow injection analysis. Analytical parameters were evaluated and, under the selected conditions, the calibration curve was linear in the range of 0.2 to 10.0 µg mL-1 with r2 = 0.998. The limit of detection was5 µg g-1 of chloride and the relative standard deviation was less than 7%. The proposed pyrohydrolysis method is relatively simple and can be used for sample preparation for further spectrophotometric determination of low concentrations of chloride in cement.

  6. Determinação espectrofotométrica de cloreto em cimento após preparo de amostra por piroidrólise

    OpenAIRE

    Fabio A. Duarte; Ederson R. Pereira; Eder L. M. Flores; Edson I. Muller; Erico M. M. Flores; Valderi L. Dressler

    2013-01-01

    A method based on pyrohydrolysis was proposed for cement sample preparation and further chloride determination by spectrophotometry using flow injection analysis. Analytical parameters were evaluated and, under the selected conditions, the calibration curve was linear in the range of 0.2 to 10.0 µg mL-1 with r2 = 0.998. The limit of detection was5 µg g-1 of chloride and the relative standard deviation was less than 7%. The proposed pyrohydrolysis method is relatively simple and can be used fo...

  7. NO{sub x} formation in cement industry clinker kilns; Formacao de NO{sub x} em fornos rotativos de producao de clinquer da industria do cimento

    Energy Technology Data Exchange (ETDEWEB)

    Signoretti, Valdir Tesche; Silva, Rogerio Jose da [Universidade Federal de Itajuba (UNIFEI), MG (Brazil)], e-mail: valdirsg@unifei.edu.br, e-mail: rogeriojs@unifei.edu.br

    2006-07-01

    This work estimates the concentration of pollutant Nox generated in the process of combustion of petroleum coke and tires in rotary kiln for clinker production in the cement industry. Using a mixture of petroleum coke and tires in the burning process, the No{sub x} and CO emissions will be evaluated in kilns with precalciner with tertiary air. The emissions will be analyzed in this installation type still considering the staging combustion as a form of reduction of the Nox emissions. The proposed model is based on the knowledge of the chemical species concentrations involved in the chemical equilibrium and also in the knowledge of the reaction kinetics of Nox and CO formation in the combustion process. It is also done in this work a revision on No{sub x}, So{sub x} and CO concerning issues related to their formation and presenting the main controlling technologies of these pollutants used in the cement industry. (author)

  8. 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.

  9. 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

  10. 76 FR 53054 - Safety Zone; TriMet Bridge Project, Willamette River; Portland, OR

    Science.gov (United States)

    2011-08-25

    ... construction site. The safety hazards in the immediate area around this construction required actions to be... construction site. Discussion of Comments and Changes There were no comments received on the notice of proposed... safety zone during the construction of the TriMet Bridge on the Willamette River, in Portland, OR....

  11. STUDY OF AMMONIA SOURCE AT A PORTLAND CEMENT PRODUCTION PLANT (JOURNAL VERSION)

    Science.gov (United States)

    A source and process sampling study was conducted at a dry process Portland Cement production plant. One aspect of the study focused on the source or point of NH3 within the production process. An extensive number of process solids from raw feeds to baghouse solids were collected...

  12. 76 FR 76760 - Gray Portland Cement and Cement Clinker From Japan

    Science.gov (United States)

    2011-12-08

    ... review. Background The Commission instituted this review on May 2, 2011 (76 FR 24519) and determined on August 5, 2011 that it would conduct an expedited review (76 FR 50252, August 12, 2011). The Commission... COMMISSION Gray Portland Cement and Cement Clinker From Japan Determination On the basis of the record...

  13. 78 FR 10005 - National Emission Standards for Hazardous Air Pollutants for the Portland Cement Manufacturing...

    Science.gov (United States)

    2013-02-12

    ... Reporting Tool FR Federal Register gr/dscf grains per dry standard cubic foot HAP hazardous air pollutants... Information Document. On July 18, 2012 (77 FR 42368), the EPA proposed to amend the Portland cement... A. PM Parametric Monitoring B. Scaling for Continuous Parametric Monitoring of THC for...

  14. Radiopacity evaluation of Portland and MTA-based cements by digital radiographic system

    Directory of Open Access Journals (Sweden)

    Alvaro Henrique Borges

    2011-06-01

    Full Text Available OBJECTIVE: The aim of the present study was to evaluate the radiopacity of Portland and MTA-based cements using the Digora TM digital radiographic system. MATERIAL AND METHODS: The performed tests followed specification number 57 from the American National Standard Institute/American Dental Association (2000 for endodontic sealing materials. The materials were placed in 5 acrylic plates, especially designed for this experiment, along with a graduated aluminum stepwedge varying from 1 to 10 mm in thickness. The set was radiographed at a 30 cm focus-object distance and with 0.2 s exposure time. After the radiographs were taken, the optical laser readings of radiographs were performed by Digora TM system. Five radiographic density readings were performed for each studied material and for each step of the aluminum scale. RESULTS: White ProRoot MTA (155.99±8.04, gray ProRoot MTA (155.96±16.30 and MTA BIO (143.13±16.94 presented higher radiopacity values (p<0.05, while white non-structural Portland (119.76±22.34, gray Portland (109.71±4.90 and white structural Portland (99.59±12.88 presented lower radiopacity values (p<0.05. CONCLUSIONS: It was concluded that MTA-based cements were the only materials presenting radiopacity within the ANSI/ADA specifications.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. Compressive Strength and Hydration Process of Self Compacting Concrete (SCC) mixed with Sea Water, Marine Sand and Portland Composite Cement

    OpenAIRE

    Tjaronge, Wihardi; Irmawaty, Rita

    2014-01-01

    In order to eliminate the main problems of shortage of clean water and fine aggregate in the low land areas and the distant islands, this research utilized sea water and marine sand and Portland composite cement to produce high performance of Self Compacting Concrete (SCC). Portland composite cement containing of fly ash. The evaluation result on the mix design, workability (slumpflow, segregation), mechanical properties (compressive strength-static modulus) and hydration process of SCC were ...

  20. 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.

  1. 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.

  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

    represents a potential alternative to traditional SCMs, used for reduction of the CO2 emission associated with cement production. It is found that the NCAS glass takes part in the hydration reactions after about two weeks of hydration and a degree of reaction of approx. 50 % is observed after 90 days of......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...... 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...

  3. Search of a prompt gamma ray for chlorine analysis in a Portland cement sample

    International Nuclear Information System (INIS)

    Prompt Gamma Ray analysis of chlorine contaminated Portland cement samples have been carried out using an accelerator-based Prompt Gamma ray Neutron Activation Analysis setup. The chlorine concentration was measured over a range of 0.25-4 wt% using 1.165 MeV capture γ-rays from chlorine. The experimental results were compared with the results of Monte Carlo simulations and an excellent agreement was observed between the two results. Further theoretical study has shown that yield of the 1.165 MeV prompt γ-rays from chlorine is not very sensitive to variation in moisture contents of the Portland sample. An order of magnitude increase in sample moisture content resulted in only 16-20% increase in yield of 1.165 MeV prompt γ-rays

  4. Search of a prompt gamma ray for chlorine analysis in a Portland cement sample

    Energy Technology Data Exchange (ETDEWEB)

    Naqvi, A.A. [Center for Applied Physical Sciences, King Fahd University of Petroleum and Minerals, Box 1815, Dhahran-31261 (Saudi Arabia)]. E-mail: annaqvi@kfupm.edu.sa; Nagadi, M.M. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran-31261 (Saudi Arabia); Kidwai, S. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran-31261 (Saudi Arabia); Khateeb-ur-Rehman [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran-31261 (Saudi Arabia); Maslehuddin, M. [Center for Engineering Sciences, King Fahd University of Petroleum and Minerals, Dhahran-31261 (Saudi Arabia)

    2004-11-11

    Prompt Gamma Ray analysis of chlorine contaminated Portland cement samples have been carried out using an accelerator-based Prompt Gamma ray Neutron Activation Analysis setup. The chlorine concentration was measured over a range of 0.25-4 wt% using 1.165 MeV capture {gamma}-rays from chlorine. The experimental results were compared with the results of Monte Carlo simulations and an excellent agreement was observed between the two results. Further theoretical study has shown that yield of the 1.165 MeV prompt {gamma}-rays from chlorine is not very sensitive to variation in moisture contents of the Portland sample. An order of magnitude increase in sample moisture content resulted in only 16-20% increase in yield of 1.165 MeV prompt {gamma}-rays.

  5. Study irradiation damage by fast neutrons in Portland cement by means of ultra-sound

    International Nuclear Information System (INIS)

    The effect of neutron irradiation in samples of Portland cement paste was evaluated, using the resonance frequency method and pulse velocity of ultra-sound technique. The samples were divide in three groups: 1) Monitoring samples; 2) Samples to gamma heating simulation; 3) Fast neutron irradiated samples in reactor core. Santa Rita Portland cement was utilized for samples preparation with water-cement rate of 0,40 l/kg. The irradiation was performed in the research reactor IEA-R1, at IPEN-CNEN/SP, with an integrated flux of 7,2 X 10 sup(18) n/cm sup(2) (E approx. 1 Mev). The samples of group 2 were submitted to special micro-waves heat treatment-with the same number of cycles of the reactor-which allowed the detection of fast neutron radiation effects within the predominant thermal effects. (author)

  6. 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.

  7. X-ray diffractometry of steam cured ordinary Portland and blast-furnace-slag cements

    International Nuclear Information System (INIS)

    This work studies some aspects of the phases produced by hydration of ordinary and blast-furnace-slag cements, at normal conditions and steam cured (60 and 950 C), using an X-ray diffraction technique. The blast-furnace-slag cement was a mixture of 50% of ordinary Portland cement and 50% of blast-furnace-slag (separately grinding). After curing the X-ray diffraction reveals that, in relation to ordinary Portland cement, the main phases in blast-furnace-slag cement are hydrated silicates and aluminates, hydro garnet, etringitte and mono sulphate. After steam curing the hydration of blast-furnace-slag cement proceeds. This is a result of the slag activation by the curing temperature. (author). 8 refs., 3 figs., 1 tab

  8. Reverse extraction of early-age hydration kinetic equation from observed data of Portland cement

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The early-age hydration of Portland cement paste has an important impact on the formation of microstructure and development of strength.However,manual derivation of hydration kinetic equation is very difficult because there are multi-phased,multi-sized and interrelated complex chemical and physical reactions during cement hydration.In this paper,early-age hydration kinetic equation is reversely extracted automatically from the observed time series of hydration degree of Portland cement using evolutionary computation method that combines gene expression programming and particle swarm optimization algorithms.In order to reduce the computing time,GPUs are used for acceleration in parallel.Studies have shown that according to the extracted kinetic equation,simulation curve of early-age hydration is in good accordance with the observed experimental data.Furthermore,this equation still has a good generalization ability even changing chemical composition,particle size and curing conditions.

  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. Hydration and microstructure of Portland cement partially substituted with ultrafine silica

    OpenAIRE

    J. I. Escalante; Gómez-Zamorano, L. Y.

    2009-01-01

    Geothermal waste, a by-product of steam power plants that use geothermal underground resources, was studied as a possible replacement for Portland cement. This waste consists primarily in amorphous nanometric silica with traces of sodium and potassium chlorides. The replacement ratios studied were 0, 10 and 20% in cements cured at 20 and 60 ºC. X-ray diffraction analysis showed that clinker phase hydration took place earlier in the presence of the geothermal waste. Scanning electron microscop...

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

    OpenAIRE

    Jovanović Nataša; Komljenović Miroslav; Petrašinović-Stojkanović Ljiljana; Baščarević Zvezdana; Bradić Violeta; Rosić Aleksandra

    2006-01-01

    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 amount...

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

    OpenAIRE

    Kara, P; Csetényi, L; Borosnyói, A

    2014-01-01

    In several countries, waste glass causes environmental concerns as quantities stockpiled exceed recycling in the packaging stream. Being amorphous and having relatively high silicium and calcium contents, glass is pozzolanic or even cementitious, when finely ground. Reducing particle sizes typically to less than 100 µm may give control over the alkali-silica reaction in concrete, therefore making this material a possible substitute to Portland cement. Such use may moderate the problem of dump...

  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. Thermal analysis of borogypsum and its effects on the physical properties of Portland cement

    International Nuclear Information System (INIS)

    Borogypsum, which consists mainly of gypsum crystals, B2O3 and some impurities, is formed during the production of boric acid from colemanite, which is an important borate ore. In this study, the effect of borogypsum and calcined borogypsum on the physical properties of ordinary Portland cement (OPC) has been investigated. The calcination temperature and transformations in the structures of borogypsum and natural gypsum were determined by differential thermal analysis (DTA), thermogravimetric analysis (TGA) and X-ray diffraction (XRD) techniques. Thermal experiments were carried out between ambient temperature and 500 deg. C in an air atmosphere at a heating rate of 10 deg. C min-1. After calculation of enthalpy and determination of conversion temperatures, borogypsum (5% and 7%), hemihydrate borogypsum (5%) and natural gypsum (5%) were added separately to Portland cement clinker and cements were ground in the laboratory. The final products were tested for chemical analysis, compressive strength, setting time, Le Chatelier expansion and fineness properties according to the European Standard (EN 196). The results show that increasing the borogypsum level in Portland cement from 5% to 7% caused an increase in setting time and a decrease in soundness expansion and compressive strength. The cement prepared with borogypsum (5%) was found to have similar strength properties to those obtained with natural gypsum, whereas a mixture containing 5% of hemihydrate borogypsum was found to develop 25% higher compressive strength than the OPC control mixtures at 28 days. For this reason, utilization of calcined borogypsum in cement applications is expected to give better results than untreated borogypsum. It is concluded that hemihydrate borogypsum could be used as a retarder for Portland cement as an industrial side. This would play an important role in reducing environmental pollution

  15. Early and Late Strength Characterization of Portland Cement Containing Calcined Low-Grade Kaolin Clay

    OpenAIRE

    Mark Bediako; Gawu, S. K. Y.; A. A. Adjaottor; John Solomon Ankrah

    2016-01-01

    Heat treated low-grade kaolin clays are now considered as a suitable pozzolanic material to metakaolins. However their suitability as a good pozzolanic material depends on the geochemistry and structure of the clay which is usually influenced by the geographical environment. This study investigated a low-grade kaolin clay from Nyamebekyere in the Ashanti Region of Ghana. The influence of the calcined material on the early and late strength development of Portland cement was analyzed. The earl...

  16. Experimental and modeling study of Portland cement paste degradation in boric acid

    International Nuclear Information System (INIS)

    In the framework of Spent Fuel Pools (SFP) lifetime studies, an investigation of the Portland cement degradation in boric acid has been requested by the Electric Power Research Institute. The main goal of this study is to identify the physico-chemical degradation mechanisms involved in boric acid media. Both experimental and modeling approaches are considered. Concerning degradation experiments, sample of cement paste are immersed during three and nine months in a boric acid solution at 2400 ppm that is periodically renewed. Boric acid concentration has been chosen to be representative of SFP solution. Results will be confronted with reactive transport numerical calculations performed by the reactive transport code HYTEC associated with a dedicated extended database called Thermoddem. The analysis of degradation solution revealed a main ions release mechanism driven by diffusion especially for calcium, nitrate, sodium and sulfate. Leaching behavior of magnesium seems to be more complex. Decalcification is the major degradation process involved, even if a non-negligible contribution of further cations (Mg2+, Na+) and anions (SO42-) has been noticed. Analysis of degradation soution also revealed that kinetic of Portland cement paste degradation in boric acid is higher than in pure water, regarding the degraded depths measured and calcium leaching rate. This observation has been confirmed by solid characterization. Microstructure analysis of degraded Portland cement paste showed a global porosity increase in the degraded zone that might be mainly attributed to Portlandite dissolution. An Ettringite reprecipitation in the degraded zone has been suspected but could also be Ettringite-like phases containing boron. The analysis techniques used did not allow us to differentiate it, and no others specific mineral phases containing boron has been identified. Profile pattern by XRD analysis allowed us to identify four zones composing the degraded Portland cement paste

  17. Influence of cellulose ethers on the kinetics of early Portland cement hydration

    OpenAIRE

    Müller, Ingo

    2006-01-01

    The phase-specific influence of cellulose ether (CEs) on Portland cement hydration was investigated in-situ, using synchrotron X-ray diffractometry. CE-caused retardation can be traced to the polymers adsorption behaviour. The adsorption decreases in following order: silicates and their hydrates (high), sulfates (low), ettringite (zero). The retarding effect is strong on silicates, moderate on sulfates and unspecific on alluminates.

  18. EFFECT OF NATURAL ZEOLITE ON THE COMPRESSIVE STRENGTH AND FREEZE-THAW RESISTANCE OF PORTLAND CEMENT

    OpenAIRE

    Bayartsetseg, E.; Lkhagvajargal, G.; Batgerel, D.; Sarangerel, D.; Ochirkhuyag, B

    2011-01-01

    Effects of zeolites in various natural deposits as replacement cementing material on mechanical performance of Portland cement were studied. The blended cement pastes with zeolites were cured at room temperature in air for various durations (1, 7 and 28 days). Mechanical performance of the blended cement samples such as setting time, volume of water, compressive strength, normal consistency and freeze-thaw resistance of the mortar are determined. The optimal substitution ratio was 20 wt. % of...

  19. Various durability aspects of calcined Kaolin-blended Portland cement pastes and concretes

    OpenAIRE

    SAILLIO, Mickael; BAROGHEL BOUNY, Véronique; PRADELLE, Sylvain

    2015-01-01

    The use of calcined clay, in the form of metakaolin (MK), as a pozzolanic constituent for concrete has received considerable attention in recent years, due to the lower CO2 emission of this supplementary cementitious material compared to the production of a classic portland cement. Furthermore, concretes incorporating MK show some improve durability properties. In this paper, the durability of concretes and cement pastes with MK as partial replacement of cement (10 and 25%) has been investiga...

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

    OpenAIRE

    Evandro Tolentino; Fernando S. Lameiras; Abdias M. Gomes; Cláudio A. Rigo da Silva; Wander L. Vasconcelos

    2002-01-01

    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...

  1. DURABILITY PERFORMANCE OF RFCC SPENT CATALYSTBLENDED PORTLAND CEMENT PASTE EXPOSED TO SEA WATER ATTACK

    OpenAIRE

    Allahverdi A.; Mahdavan M.

    2013-01-01

    This paper discusses the performance of the paste of Portland cement blended with spent catalyst from Resid Fluidized Catalytic Cracking (RFCC) unit of petroleum refining processes in sea water. 28-day cured paste specimens prepared from binary cement mixes containing different amounts of spent catalyst were exposed to Persian Gulf sea water. Compressive strength, weight, and length changes of the specimens were monitored and considered for evaluating the extent of deterioration. Laboratory t...

  2. Tabular data base construction and analysis from thematic classified Landsat imagery of Portland, Oregon

    Science.gov (United States)

    Bryant, N. A.; George, A. J., Jr.; Hegdahl, R.

    1977-01-01

    A systematic verification of Landsat data classifications of the Portland, Oregon metropolitan area has been undertaken on the basis of census tract data. The degree of systematic misclassification due to the Bayesian classifier used to process the Landsat data was noted for the various suburban, industrialized and central business districts of the metropolitan area. The Landsat determinations of residential land use were employed to estimate the number of automobile trips generated in the region and to model air pollution hazards.

  3. 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.

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

    Directory of Open Access Journals (Sweden)

    Riccardo Ricceri

    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.

  5. 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.

  6. Ettringite and C-S-H Portland cement phases for waste ion immobilization: A review

    International Nuclear Information System (INIS)

    The formation, structure and chemistry of the ettringite and C-S-H phases of Portland cement have been reviewed as they relate to waste ion immobilization. The purpose of this review was to investigate the use of Portland cement as a host for priority metallic pollutants as identified by the Environmental Protection Agency and as a host for radioactive waste ions as identified in 40 CFR 191. Ettringite acts as host to a number of these ions in both the columnar and channel sections of the crystal structure. Substitutions have been made at the calcium, aluminum, hydroxide and sulfate sites. C-S-H also hosts a number of the waste species in both ionic and salt form. Immobilization mechanisms for C-S-H include sorption, phase mixing and substitution. The following ions have not apparently been reported as specifically immobilized by one of these phases: Ag, Am, Np, Pu, Ra, Tc, Th and Sn; however, some of these ions are immobilized by Portland cement

  7. 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.

  8. Possibility of using waste tire rubber and fly ash with Portland cement as construction materials.

    Science.gov (United States)

    Yilmaz, Arin; Degirmenci, Nurhayat

    2009-05-01

    The growing amount of waste rubber produced from used tires has resulted in an environmental problem. Recycling waste tires has been widely studied for the last 20 years in applications such as asphalt pavement, waterproofing systems and membrane liners. The aim of this study is to evaluate the feasibility of utilizing fly ash and rubber waste with Portland cement as a composite material for masonry applications. Class C fly ash and waste automobile tires in three different sizes were used with Portland cement. Compressive and flexural strength, dry unit weight and water absorption tests were performed on the composite specimens containing waste tire rubber. The compressive strength decreased by increasing the rubber content while increased by increasing the fly ash content for all curing periods. This trend is slightly influenced by particle size. For flexural strength, the specimens with waste tire rubber showed higher values than the control mix probably due to the effect of rubber fibers. The dry unit weight of all specimens decreased with increasing rubber content, which can be explained by the low specific gravity of rubber particles. Water absorption decreased slightly with the increase in rubber particles size. These composite materials containing 10% Portland cement, 70% and 60% fly ash and 20% and 30% tire rubber particles have sufficient strength for masonry applications. PMID:19110410

  9. Basalt mine-tailings as raw-materials for Portland clinker Rejeitos da mineração de basalto como matérias-primas para clínquer Portland

    Directory of Open Access Journals (Sweden)

    F. R. D Andrade

    2010-03-01

    Full Text Available Large volumes of waste materials are produced by crushing of basaltic rocks for aggregate production, which is widely used in regions that lack rocks of granitic or gneissic composition. Two types of waste materials are produced (a quarry fines, which are in part used as fine aggregates in concrete and (b vesicular basalt, a porous variety of basalt that is useless as aggregate. This paper presents a procedure to use basaltic mine-tailings as raw-mixtures for Portland cement by adjusting the proportion of the other raw-materials (limestone, clay, iron ore. It is demonstrated that there is no need for additional fluxes to the basalt-bearing raw-mixtures, since the setting of the chemical parameters is enough to guarantee clinker formation. Two series of experimental clinkers were synthesized with raw-mixtures containing residues from a basalt quarry that produces aggregates for concrete. Experimental clinkers were produced from raw-mixtures with similar lime saturation factors, silica and alumina modules, which were set by adjusting the proportions of limestone, clay and iron ore to the varying proportions of basaltic materials added to them. One series of clinkers was made with basalt quarry fines, which are in part used as fine aggregate, but also accumulate as mine-tailings. Other series was made using vesicular (porous basalt, a variety not resistant enough to be used as aggregate. It is demonstrated that the basaltic composition is fully compatible with clinker production, and no addition of fluxes or other additions is required. Composition of the raw-mixtures was checked by chemical analysis. Quantitative phase analysis of the clinkers was made by optical microscopy point counting, together with qualitative X-ray diffraction. All mixtures produced clinkers with acceptable proportions of major and minor crystalline phases, inside the range of common industrial Portland clinkers.Duas séries de clínqueres experimentais foram sintetizadas

  10. 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.

  11. Deposição de ácido linoléico conjugado (CLA) em tilápias-do-nilo Deposition of conjugated linoleic acid (CLA) in Nile tilapia

    OpenAIRE

    Lilian Dena dos Santos; Wilson Massamitu Furuya; Makoto Matsushita; Lilian Carolina Rosa da Silva; Tarcila Souza de Castro Silva; Daniele Botaro; Priscila Pinsetta Sales

    2007-01-01

    Objetivou-se avaliar a deposição de ácido linoléico conjugado (CLA) em filés de tilápia-do-nilo (Oreochromis niloticus). Foram utilizados peixes com 121,08 ± 8,48 g, distribuídos em quatro caixas de cimento amianto (1,0 m³ cada uma) e arraçoados até saciedade aparente, duas vezes ao dia, durante 49 dias. Como alimento, utilizou-se ração comercial extrusada com 28% de PB e 3.000 kcal de energia digestível/kg, acrescida de 2% do produto comercial Luta-CLAâ (BASF Brasil). No início do exp...

  12. A utilização de resíduos de pneus inservíveis em argamassa de revestimento = The use of scrap rubber tire residues in finishing mortar for construction

    OpenAIRE

    José Aparecido Canova; Rosangela Bergamasco; Generoso De Angelis Neto

    2007-01-01

    Este trabalho avalia uma argamassa de revestimento com resíduos de pneus inservíveis, produzida com cimento, cal virgem e areia, no traço 1: 1,5: 9 (em volume) e adição de pó de borracha moída, nas proporções 0, 6, 8, 10 e 12% do volume de agregado. Avaliou-se a massa específica, o teor de ar incorporado e a retenção de água no estado plástico e em corpos de prova cilíndricos, a resistência à compressão axial, a resistência à tração por compressão diametral, o módulo de deformação estática e ...

  13. Public health assessment for McCormick and Baxter Creosoting Company (Portland), Portland, Multnomah County, Oregon, Region 10. Cerclis No. ORD009020603. Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-06-13

    The McCormick and Baxter Creosoting site is located on the Willamette River in Portland, Oregon. ATSDR considers the site to have been a public health hazard for former plant workers because of past ingestion exposure to arsenic, creosote, pentachlorophenol, polychlorinated dibenzodioxins, and dibenzofurans at levels of public health concern. The site also poses an ongoing and future public health hazard because people might encounter hazardous chemicals along the shoreline on or near the site at levels that can damage the skin, as was reported to have happened to two boys. Finally, dioxin levels would pose a public health hazard if people subsist on crayfish and suckers contaminated with polychlorinated dibenzodioxins and dibenzofurans.

  14. Network Level Carbon Dioxide Emissions From On-road Sources in the Portland OR, (USA) Metropolitan Area

    Science.gov (United States)

    Powell, J.; Butenhoff, C. L.; Rice, A. L.

    2014-12-01

    To mitigate climate change, governments at multiple levels are developing policies to decrease anthropogenic carbon dioxide (CO2) emissions. The City of Portland (Oregon) and Multnomah County have adopted a Climate Action Plan with a stated goal of reducing emissions to 80% below 1990 levels by 2050. The transportation sector alone accounts for about 40% of total emissions in the Portland metropolitan area. Here we show a new street-level model of on-road mobile CO2 emissions for the Portland, OR metropolitan region. The model uses hourly traffic counter recordings made by the Portland Bureau of Transportation at 9,352 sites over 21 years (1986-2006), augmented with freeway loop detector data from the Portland Regional Transportation Archive Listing (PORTAL) transportation data archive. We constructed a land use regression model to fill in traffic network gaps with traffic counts as the dependent variable using GIS data such as road class (32 categories) and population density. The Environmental Protection Agency (EPA) MOtor Vehicle Emission Simulator (MOVES) model was used to estimate transportation CO2 emissions. The street-level emissions can be aggregated and gridded and used as input to atmospheric transport models for comparison with atmospheric measurements. This model also provides an independent assessment of top-down inventories that determine emissions from fuel sales, while being an important component of our ongoing effort to assess the effectiveness of emission mitigation strategies at the urban scale.

  15. Effect of thermocycling on the bond strength of a glass-infiltrated ceramic and a resin luting cement Efeito da ciclagem térmica sobre a resistência de união entre uma cerâmica infiltrada com vidro e um cimento resinoso

    Directory of Open Access Journals (Sweden)

    Osvaldo Daniel Andreatta Filho

    2003-03-01

    ílica/ silanização foi cimentada com Panavia F, sob peso constante de 750g, a outro bloco idêntico de resina composta Clearfil AP-X (Kuraray. Os blocos de resina foram obtidos por meio de duplicação daqueles de cerâmica a partir de moldes com silicona de adição Express (3M. Os quatro conjuntos formados por cerâmica, cimento e resina foram seccionados em 20 corpos-de-prova com forma de palitos, de modo que a região adesiva apresentasse 1mm² de área. Dois grupos (n=10 foram constítuidos: G1- estocagem por 7 dias em água deionizada à 36 ± 2ºC; G2- 1500 ciclos entre 5ºC e 55ºC com intervalos de 30 segundos. A seguir, foi realizado o teste de microtração em máquina de ensaio universal (EMIC com velocidade de 0,5 mm/min. Os resultados mostraram que os valores médios de tensão de ruptura (MPa para o grupo G2: (22,815 ± 5,254 não tiveram diferenças estatisticamente significantes daqueles do grupo G1: (25,628 ± 3,353 (t= 1,427; gl = 18; p-valor = 0,171, ao nível de significância de 5%. A partir destes resultados, entendemos lícito concluir que o efeito da ciclagem térmica não produziu alterações estatisticamente significantes nos valores da resistência adesiva.

  16. Phytochemical and Biological Studies of <em>Agave em>attenuata>

    OpenAIRE

    Vincenzo De Feo; Muhammad Riaz; Nasir Rasool; Muhammad Zubair; Komal Rizwan; Muhammad Zia-Ul-Haq

    2012-01-01

    The present study was conducted to examine various biological activities of a methanol extract of <em>Agave attenuataem> leaves. GC-MS analysis of the <em>n>-hexane fraction from the extract revealed the presence of 31 compounds, with mono-2-ethylhexyl phthalate (11.37%), 1,2-benzenedicarboxylic acid (6.33%), <em>n>-docosane (6.30%) and eicosane (6.02%) as the major components. The leaves contained appreciable levels of total phenolic contents (10...

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

    International Nuclear Information System (INIS)

    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), 29Si and 27Al 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. - Highlights: ► This is the first study of Portland cement-based biomaterials by 27Al and 29Si NMR. ► 20 wt.% ZrO2 radiopacifier accelerates the early cement hydration reactions. ► Extent of hydration after 6 h is increased from 5.7% to 15% in the presence of ZrO2. ► Initial and final setting times are reduced by 25 and 22 min, respectively. ► ZrO2 provides nucleation sites for the precipitation of early hydration products.

  18. Estudo por microscopia óptica e lupa das características mineralógicas e microestruturais do clínquer aplicado ao processo de moagem e qualidade do cimento

    OpenAIRE

    Souza Vládia Cristina Gonçalves; Sampaio Carlos Hoffmann; Tavares Luis Marcelo Marques

    2002-01-01

    Tem sido largamente estudada a influência das características mineralógicas e microestruturais do clínquer sobre a sua moabilidade, devido ao alto custo dessa etapa na fabricação de cimento e às exigências de qualidade do mercado. Nesse trabalho, usaram-se o microscópio óptico e a lupa para descrever e analisar as amostras de partículas de diversos tamanhos de clínquer, provenientes de uma fábrica situada no sul do Brasil. Através desse estudo, foi constatada, nas amostras coletadas, a ocorrê...

  19. 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; Carvalho, Ricardo Marins; TAGA Eulázio; 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...

  20. Resistência mecânica a quente de concretos refratários aluminosos zero-cimento auto-escoantes contendo adições de microssílica e microssílica coloidal

    OpenAIRE

    Gerotto M. V.; Pileggi R. G.; Pandolfelli V. C.

    2000-01-01

    Concretos refratários aluminosos contendo microssílica apresentam um grande potencial de aplicação tecnológica pela possibilidade de formação da fase mulita através da reação entre Al2O3 e SiO2. Porém, segundo o diagrama Al2O3 - SiO2 - CaO, seu uso é limitado a temperaturas próximas a 1300 ºC uma vez que a presença do CaO, contido no cimento de aluminato de cálcio, leva a formação de fases líquidas que prejudicam fortemente a sua resistência mecânica a altas temperaturas. Recentemente foi mos...

  1. 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.

  2. Structural Evaluation and Performance of Portland Cement Concretes After Exposure to High Temperatures

    Directory of Open Access Journals (Sweden)

    Evandro Tolentino

    2002-03-01

    Full Text Available We evaluated the "residual" thermal conductivity of Portland cement concretes (with characteristic compressive strength at 28 days, f ck, of 20 MPa and 50 MPa at room temperature after heat-treating at 180 °C, 300 °C and 600 °C. The description of the geometry of the structure was carried out using mercury intrusion porosimetry and nitrogen sorption. The results showed a decreasing tendency of residual thermal conductivity, which we attributed to heat-induced concrete degradation. Furthermore, the results from mercury intrusion porosimetry and nitrogen sorption tests showed that a coarser pore structure is produced with the raise of heat-treatment temperatures.

  3. Structural Evaluation and Performance of Portland Cement Concretes After Exposure to High Temperatures

    OpenAIRE

    Evandro Tolentino; Fernando S. Lameiras; Abdias M. Gomes; Cláudio A. Rigo da Silva; Wander L. Vasconcelos

    2002-01-01

    We evaluated the "residual" thermal conductivity of Portland cement concretes (with characteristic compressive strength at 28 days, f ck, of 20 MPa and 50 MPa) at room temperature after heat-treating at 180 °C, 300 °C and 600 °C. The description of the geometry of the structure was carried out using mercury intrusion porosimetry and nitrogen sorption. The results showed a decreasing tendency of residual thermal conductivity, which we attributed to heat-induced concrete degradation. Furthermor...

  4. 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.

  5. 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.

  6. Electromagnetic interference shielding with Portland cement paste containing carbon materials and processed fly ash

    OpenAIRE

    Zornoza, E.; Catalá, G.; Jiménez, F.; Andión, L. Gª; Garcés, P.

    2010-01-01

    The study described in this article explored the effect of adding different types of carbon materials (graphite powder and three types of carbon fibre), fly ash (with 5.6%, 15.9% and 24.3% Fe2O3), and a mix of both on electromagnetic interference (EMI) shielding in Portland cement pastes. The parameters studied included the type and aspect ratio of the carbonic material, composite material thickness, the frequency of the incident electromagnetic r...

  7. Immobilisation Of Spent Ion Exchange Resins Using Portland Cement Blending With Organic Material

    International Nuclear Information System (INIS)

    Immobilisation of spent ion exchange resins (spent resins) using Portland cement blending with organic material for example bio char was investigated. The performance of cement-bio char matrix for immobilisation of spent ion exchange resins was evaluated based on their compression strength and leachability under different experimental conditions. The results showed that the amount of bio char and spent resins loading effect the compressive strength of the waste form. Several factors affecting the leaching behaviour of immobilised spent resins in cement-bio char matrix. (author)

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

    DEFF Research Database (Denmark)

    Lindgreen, Holger; Geiker, Mette Rica; 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......, in comparison to the pure cement pasta and the paste containing kaolinite, a more open pore structure consisting of fine pores. Silica fume paste contains a significant amount of closed pores. As a secondary result, it is demonstrated that both the degree and duration of sample drying strongly modifies...

  9. AVALIAÇÃO DE GEOPOLÍMEROS COMO REVESTIMENTO ANTICORROSIVO

    OpenAIRE

    Mário Lucas Santana Silva; André de Araújo Abílio; Felipe Rocha Machado; Angelus Giuseppe Pereira da Silva; Dylmar Penteado Dias

    2014-01-01

    A corrosão consiste na deterioração dos materiais pela ação química ou eletroquímica do meio, podendo estar ou não associado a esforços mecânicos. Com as constantes pesquisas efetivadas na inovação de materiais para uso industrial, um novo material mostrou num primeiro momento um grande potencial para aplicações anticorrosivas e como sendo uma alternativa viável ao uso do cimento Portland. Denominado geopolímero, sua estrutura baseada em álcali-ativadores e compostos silicosos de ...

  10. Healing of apical rarefaction of three nonvital open apex anterior teeth using a white portland cement apical plug

    Directory of Open Access Journals (Sweden)

    Amitabha Chakraborty

    2012-01-01

    Full Text Available The major challenge of performing root canal treatment in an open apex pulp-less tooth is to obtain a good apical seal. MTA has been successfully used to achieve a good apical seal, wherein the root canal obturation can be done immediately. MTA and White Portland Cement has been shown similarity in their physical, chemical and biological properties and has also shown similar outcome when used in animal studies and human trials. In our study, open apex of three non vital upper central incisors has been plugged using modified white Portland cement. 3 to 6 months follow up revealed absence of clinical symptoms and disappearance of peri-apical rarefactions. The positive clinical outcome may encourage the future use of white Portland cement as an apical plug material in case of non vital open apex tooth as much cheaper substitute of MTA.

  11. Properties of Portland-Composite Cements with metakaolin: Commercial and manufactured by Thermal Activation of Serbian Kaolin Clay

    Directory of Open Access Journals (Sweden)

    Mitrovic A.

    2012-09-01

    Full Text Available Portland-composite cements (CEM II were prepared with addition of 5 to 35% of metakaolin (MK, manufactured by thermal activation/calcination of Serbian kaolin clay, and commercial matakaolin (CMK. Performance of the composite cements was evaluated, through the setting time (initial and final, compressive strengths (for ages 2, 7, 28, 90 and 180 days and soundness, and compared with control cement (Portland cement – CEM I. Setting time (initial and final is accelerated in Portlandcomposite cements, for both metakaolins used. The acceleration is higher in cement with addition of commercial metakaolin. Lower compressive strength is obtained after 2 days of curing for all Portland-composite cements in comparison with control cement, since pozzolanic reaction still did not show its effect. After 7 days, pozzolanic reaction show its effect, manifested as compressive strength increase of Portland-composite cements with addition of up to 35% of CMK, and 25% in the case of cements with MK. After 28 days compressive strength was higher than that for control cement for cements prepared with addition of CMK, and with addition of up to 25% MK. After 90 days increased compressive strength was noticed with addition of 10 - 20% of CMK, and with 10 and 15% of MK, while after 180 days addition of both metakaolins influences compressive strength decrease. The results of the soundness, 0.5 mm for CEM I, and 1.0 mm in most Portland-composite cements indicate soundness increase with addition of metakaolins. Generally, better performance of Portland-composite cements was obtained with addition of commercial metakaolin, which may be attributed to the differences in the pozzolanic activity of the applied metakaolins, 20.5 MPa and 14.9 MPa for CMK and MK, respectively. By our previous findings pozzolanic activity of the thermally activated clay may be increased by subsequent milling of the metakaolin manufactured by thermal activation process.

  12. Tsetsaut History: The Forgotten Tribe of Southern Southeast Alaska. Portland Canal Early History (Misty Fiord National Monument). Alaska Historical Commission Studies in History #147.

    Science.gov (United States)

    Dangeli, Reginald H.

    Written by one of the tribe's few remaining members and based on oral history and legend, this study traces the history of the Tsetsaut tribe, ancient original inhabitants of the Portland Canal area of southeastern Alaska. Chapters recount the quest for the coast, legends of Portland Canal, exploration of the area, material culture, establishment…

  13. A comparative evaluation of compressive strength of Portland cement with zinc oxide eugenol and Polymer-reinforced cement: An in vitro analysis

    Directory of Open Access Journals (Sweden)

    S Prakasam

    2014-01-01

    These samples were further subdivided based on time interval and were tested at 1 hour, 24 hours and at 7 th day. After each period of time all the specimens were tested by vertical CVR loaded frame with capacity of 5 tones/0473-10kan National Physical laboratory, New Delhi and the results were statistically analyzed using ANOVA and Scheffe test. Results: Polymer-reinforced cement with 50% Portland cement, Zinc oxide with 50% Portland cement, Polymer-reinforced cement with 25% Portland cement and Zinc oxide with 25% Portland cement exhibited higher compressive strength when compared to Zinc oxide with 0% Portland cement and Polymer-reinforced cement with 0% Portland cement, at different periods of time. The difference between these two groups were statistically significant (P < 0.05 and it is suggested that mixture of 50% and 25% Portland cement in Zinc oxide eugenol and Polymer-modified zinc oxide cement can be used as core build up material and permanent filling material. Conclusion: It is concluded that 50% and 25% Portland cement in zinc oxide eugenol and polymer-modified zinc oxide eugenol results in higher compressive strength and hence can be used as permanent filling material and core built-up material.

  14. The influence of shrinkage-cracking on the drying behaviour of White Portland cement using Single-Point Imaging (SPI).

    Science.gov (United States)

    Beyea, S D; Balcom, B J; Bremner, T W; Prado, P J; Cross, A R; Armstrong, R L; Grattan-Bellew, P E

    1998-11-01

    The removal of water from pores in hardened cement paste smaller than 50 nm results in cracking of the cement matrix due to the tensile stresses induced by drying shrinkage. Cracks in the matrix fundamentally alter the permeability of the material, and therefore directly affect the drying behaviour. Using Single-Point Imaging (SPI), we obtain one-dimensional moisture profiles of hydrated White Portland cement cylinders as a function of drying time. The drying behaviour of White Portland cement, is distinctly different from the drying behaviour of related concrete materials containing aggregates. PMID:9875607

  15. High Resolution Modeling of Anthropogenic and Biogenic Carbon Dioxide Fluxes From the Portland Oregon Metropolitan Area

    Science.gov (United States)

    Butenhoff, C. L.; Powell, J.; Tran, D.; Rice, A. L.

    2013-12-01

    The future of the North American carbon cycle is heavily dependent on urban ecosystems and their development. Around 75-80% of the current U.S. population is urbanized and this percentage is likely to increase in the future. Despite the lack of national climate policy, cities nationwide are developing their own plans to reduce carbon dioxide (CO2) emissions. The city of Portland OR for example (along with Multnomah County) has in place an ambitious goal of reducing CO2 emissions by 80% by the year 2050. Monitoring and verifying emission reductions will be integral to the successful operation of this and other mitigation policies. To do so requires both the modeling and measurement of CO2 at high spatial and temporal resolution. To this effort we developed gridded inventories of anthropogenic and biogenic fluxes of CO2 from Portland and the surrounding metropolitan region at 1-km resolution and at hourly time steps. Mobile emissions were estimated using traffic count data, a land-use regression model, and the EPA MOVES model. Biogenic fluxes of CO2 were calculated using high resolution remote sensing vegetation maps and the Vegetation Photosynthesis and Respiration Model coupled to the Weather Research and Forecasting Model (WRF-VPRM). This is part of an on-going effort to constrain emission estimates using measurements of CO2 from throughout the region. Here we compare simulated concentrations of CO2 with data available from three sites, representing upwind, downwind, and city center conditions.

  16. 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%.

  17. 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.

  18. 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.

  19. 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.

  20. Ordinary Portland Cement matrix for solidification of cellulosic protective clothes hazardous wastes

    International Nuclear Information System (INIS)

    The used cellulosic protective clothes constitutes considerable fraction of the hazardous and radioactive wastes accumulated during the practical daily life. The direct solidification of these wastes with ordinary Portland cement resulted in waste forms having undesired characters, therefore, it is recommended to immobilize the secondary waste solutions coming from the oxidative degradation of the used protective clothes waste simulates rather than direct imbedding. IR analyses, X-ray diffraction and thermal characteristics for products of both direct encapsulation of the waste and the cementation of its degradation products were performed to evaluate the properties of the final waste cemented form before their disposal. Based on the results reached from X-ray diffraction, IR spectrograms and thermal analyses reports, it could be stated that no detectable changes in hydration and curing coarse of ordinary Portland cement when mixing the residual secondary waste solution resulting from the oxidative degradation of the used protective clothes waste simulate compared with mixing cement with water and in reverse with imbedding the unprocessed waste in cement matrix

  1. 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.

  2. The impact of zirconium oxide nanoparticles on the hydration chemistry and biocompatibility of white Portland cement.

    Science.gov (United States)

    Li, Qiu; Deacon, Andrew D; Coleman, Nichola J

    2013-01-01

    Zirconium oxide (ZrO2) has been nominated as a radiopacifying agent for use in MTA-like Portland cement-based root-filling materials. This research examines the impact of 20 wt% ZrO2 nanoparticles in the size range 50 to 75 nm on the early hydration chemistry of white Portland cement. Nano-ZrO2 was found to accelerate the degree of hydration by 26% within the first 24 h by presenting efficient nucleation sites for the precipitation and growth of the early C-S-H gel products. The presence of nano-ZrO2 was also found to divert the fate of the aluminium-bearing reaction products by lowering the ettringite to monosulphate ratio, reducing the size of the ettringite crystals and by increasing the Al:Si ratio of the C-S-H gel phase. The chemical and microstructural changes conferred upon the cement matrix by the nano-ZrO2 particles had a positive impact on in vitro biocompatibility with respect to MG63 osteosarcoma cells (via MTT assay). PMID:24088838

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

    Science.gov (United States)

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

    2016-01-01

    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. PMID:27347987

  4. 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. PMID:24100236

  5. Evaluation of physico-chemical properties of Portland cements and MTA

    Directory of Open Access Journals (Sweden)

    Jorge Luis Gonçalves

    2010-09-01

    Full Text Available The purpose of this study was to evaluate the hydrogenionic potential and electrical conductivity of Portland cements and MTA, as well as the amount of arsenic and calcium released from these materials. In Teflon molds, samples of each material were agitated and added to plastic flasks containing distilled water for 3, 24, 72 and 168 h. The results were analyzed with a Kruskal-Wallis non-parametric test for global comparisons and a Dunn-Tukey test for pairwise comparisons. The results revealed no significant differences in the pH of the materials (p > 0.05. The electrical conductivity of the cements were not statistically different (p > 0.05. White non-structural cement and MTA BIO released the largest amount of calcium ions into solution (p 0.05. The results indicated that the physico-chemical properties of Portland cements and MTA were similar. Furthermore, all materials produced an alkaline environment and can be considered safe for clinical use because arsenic was not released. The electrical conductivity and the amount of calcium ions released into solution increased over time.

  6. Assessment of diabetic teleretinal imaging program at the Portland Department of Veterans Affairs Medical Center

    Directory of Open Access Journals (Sweden)

    Grace L. Tsan, OD

    2015-06-01

    Full Text Available We conducted a retrospective chart review of 200 diabetic patients who had teleretinal imaging performed between January 1, 2010, and January 1, 2011, at Portland Department of Veterans Affairs (VA Medical Center outpatient clinics to assess the effectiveness of the diabetic teleretinal imaging program. Twenty patients (10% had diabetic retinopathy. Ninety percent of the available teleretinal imaging studies were of adequate quality for interpretation. In accordance with local VA policy at that time, all teleretinal imaging patients should have been referred for a dilated retinal examination the following year. Image readers referred 97.5% of the patients to eye clinics for subsequent eye examinations, but the imagers scheduled appointments for only 80% of these patients. The redundancy rate, i.e., patients who had an eye examination within the past 6 mo, was 11%; the duplicate recall rate, i.e., patients who had a second teleretinal imaging performed within 1 yr of the eye examination, was 37%. Rates of timely diabetic eye examinations at clinics with teleretinal imaging programs, particularly when teleretinal imaging and eye clinics were colocated at the same community-based outpatient clinic, were higher than at those without a teleretinal imaging program. We concluded that the Portland VA Medical Center's teleretinal imaging program was successful in increasing the screening rate for diabetic retinopathy.

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

    Science.gov (United States)

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

    2016-01-01

    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. PMID:27347987

  8. 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. PMID:26615227

  9. 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)

  10. 76 FR 34252 - Notice Pursuant to the National Cooperative Research and Production Act of 1993; Portland Cement...

    Science.gov (United States)

    2011-06-13

    ... Cooperative Research and Production Act of 1993, 15 U.S.C. 4301 et seq. (``the Act''), Portland Cement... published a notice in the Federal Register pursuant to Section 6(b) of the Act on February 5, 1985 (50 FR... in the Federal Register pursuant to Section 6(b) of the Act on March 7, 2011 (76 FR 12370)....

  11. 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

  12. Determination of absorption length of CO2 and high power diode laser radiation for ordinary Portland cement

    OpenAIRE

    Lawrence, Jonathan; Johnston, Emma P.; Li, Lin

    2000-01-01

    The laser beam absorption lengths of CO2 and a high power diode laser (HPDL) radiation for the ordinary Portland cement (OPC) surface of concrete have been determined. By employing Beer-Lambert’s law the absorption lengths for concrete of CO2 and a HPDL radiation were 470±22 μm and 177±15 μm respectively.

  13. 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.

  14. "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…

  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

    OpenAIRE

    Celso Y. Kawabata; Rafael C. de Castro; Holmer Savastano Júnior

    2005-01-01

    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 cime...

  16. Resistência a compressão de tijolos de solo-cimento fabricados com o montículo do cupim Cornitermes cumulans (Kollar, 1832 Resistance the compression of manufactured cement bricks ground with the wooded hill of termite Cornitermes cumulans (Kollar, 1832

    Directory of Open Access Journals (Sweden)

    Leandro Queiroz Corrêa de Albuquerque

    2008-04-01

    Full Text Available Objetivou-se neste trabalho, comparar a resistência à compressão de tijolos de solo-cimento fabricados com o montículo do cupim Cornitermes cumulans (Kollar, 1832, com tijolos que utilizaram como matéria prima um NEOSSOLO QUARTZARÊNICO (EMBRAPA, 1999, ambos submetidos a duas idades de cura (07 ou 28 dias. O experimento foi montado em delineamento inteiramente casualizado, em esquema fatorial 2x2, sendo analisados dois cofatores: a matéria prima base e a idade de cura. Os ensaios físicos e mecânicos obedeceram às prescrições das normas da Associação Brasileira de Normas Técnicas NBR-8492 (ABNT, 1982 e NBR-8491 (ABNT, 1984. Concluiu-se que a resistência à compressão dos tijolos foi maior com o aumento das idades de cura. O tratamento T4 apresentou maior valor de resistência à compressão, não diferindo estatisticamente dos tratamentos T2 e T1. Os tijolos fabricados com o montículo do cupim C. cumulans (Kollar, 1832 apresentaram diminuição da absorção de água com o aumento das idades de cura, o que normalmente corresponde a um maior aumento da resistência à compressão, ao contrário dos que utilizaram o NEOSSOLO QUARTZARÊNICO (EMBRAPA, 1999.The aim of this research was to compare the compressive strength of ground-cement bricks manufactured with the wooded hill of termite Cornitermes cumulans (Kollar, 1832, to bricks that they were used as quartzaremico raw material one NEOSSOLO QUARTZARÊNICO (EMBRAPA, 1999, both submitted to two ages of cure (07 or 28 days. The experiment was performed in entirely randomized delineation, in factorial project 2x2, being analyzed two cofactors: the raw material base and age of cure. The physical and mechanical assays obeyed the lapsing of the norm of the Brazilian Association of Technical Rules NBR-8492 (ABNT, 1982 and NBR-8491 (ABNT, 1984. One concluded that the compressive strength of the bricks was bigger with the increase of the ages of cure. The T4 treatment presented bigger

  17. Modeling the degradation of Portland cement pastes by biogenic organic acids

    International Nuclear Information System (INIS)

    Reactive transport models can be used to assess the long-term performance of cement-based materials subjected to biodegradation. A bioleaching test (with Aspergillus niger fungi) applied to ordinary Portland cement pastes during 15 months is modeled with HYTEC. Modeling indicates that the biogenic organic acids (acetic, butyric, lactic and oxalic) strongly accelerate hydrate dissolution by acidic hydrolysis whilst their complexation of aluminum has an effect on the secondary gel stability only. The deepest degradation front corresponds to portlandite dissolution and decalcification of calcium silicate hydrates. A complex pattern of sulfate phases dissolution and precipitation takes place in an intermediate zone. The outermost degraded zone consists of alumina and silica gels. The modeling accurateness of calcium leaching, pH evolution and degradation thickness is consistently enhanced whilst considering increase of diffusivity in the degraded zones. Precipitation of calcium oxalate is predicted by modeling but was hindered in the bioleaching reactor.

  18. 谈硅酸盐水泥的强度%On strength of Portland cement

    Institute of Scientific and Technical Information of China (English)

    牛崇霞

    2012-01-01

    The paper illustrates the formation and development of the cement strength,analyzes the factors which influence the strength of the Portland cement from the mineral components of the clinker,the cement fineness,and the construction conditions,and points out the cement strength could adhere to the regulation of the relative standards only by controlling these factors in a strict way.%简要阐述了水泥强度的产生与发展,从熟料的矿物组成、水泥细度、施工条件三方面分析了影响硅酸盐水泥强度的因素,指出只有严格控制这些因素,才能保证水泥强度符合有关标准规定。

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

    International Nuclear Information System (INIS)

    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)

  20. A combined QXRD/TG method to quantify the phase composition of hydrated Portland cements

    Energy Technology Data Exchange (ETDEWEB)

    Soin, Alexander V.; Catalan, Lionel J.J. [Department of Chemical Engineering, Lakehead University, 955 Oliver Road, Thunder Bay, Ontario P7B 5E1 (Canada); Kinrade, Stephen D., E-mail: stephen.kinrade@lakeheadu.ca [Department of Chemistry, Lakehead University, 955 Oliver Road, Thunder Bay, Ontario P7B 5E1 (Canada)

    2013-06-15

    A new method is reported for quantifying the mineral phases in hydrated cement pastes that is based on a combination of quantitative X-ray diffractometry (QXRD) and thermogravimetry (TG). It differs from previous methods in that it gives a precise measure of the amorphous phase content without relying on an assumed stoichiometric relationship between the principal hydration products, calcium hydroxide (CH) and calcium silicate hydrate (C–S–H). The method was successfully applied to gray and white ordinary Portland cements (GOPC and WOPC, respectively) that were cured for up to 56 days. Phase distributions determined by QXRD/TG closely matched those from gray-level analysis of backscattered scanning electron microscope (BSEM) images, whereas elemental compositions obtained for the amorphous phase by QXRD/TG agreed well with those measured by quantitative energy dispersive X-ray spectroscopy (EDS)

  1. 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

  2. Plant-Wide Energy Efficiency Assessment at the Arizona Portland Cement Plant in Rillito, Arizona

    Energy Technology Data Exchange (ETDEWEB)

    Stephen J. Coppinger, P.E.; Bruce Colburn, Ph.D., P.E., CEM

    2007-05-17

    A Department of Energy Plant-wide Assessment was undertaken by Arizona Portland Cement (APC) beginning in May 2005. The assessment was performed at APC’s cement production facility in Rillito, Arizona. The assessment included a compressed air evaluation along with a detailed process audit of plant operations and equipment. The purpose of this Energy Survey was to identify a series of energy cost savings opportunities at the Plant, and provide preliminary cost and savings estimates for the work. The assessment was successful in identifying projects that could provide annual savings of over $2.7 million at an estimated capital cost of $4.3 million. If implemented, these projects could amount to a savings of over 4.9 million kWh/yr and 384,420 MMBtu/year.

  3. 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)

  4. 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.

  5. Chemical and morphological characteristics of mineral trioxide aggregate and Portland cements.

    Science.gov (United States)

    Khan, Shahbaz; Kaleem, Muhammad; Fareed, Muhammad Amber; Habib, Amir; Iqbal, Kefi; Aslam, Ayesha; Ud Din, Shahab

    2016-01-01

    The purpose of this study was to investigate the chemical composition and particle morphology of white mineral trioxide aggregate (WMTA) and two white Portland cements (CEM 1 and CEM 2). Compositional analysis was performed by energy dispersive X-ray spectroscopy, X-ray fluorescence spectrometry and X-ray diffraction whereas, morphological characteristics were analyzed by scanning electron microscope and Laser scattering particle size distribution analyzer. The elemental composition of WMTA, CEM 1 and CEM 2 were similar except for the presence of higher amounts of bismuth in WMTA. Calcium oxide and silicon oxide constitute the major portion of the three materials whereas, tricalcium silicate was detected as the major mineral phase. The particle size distribution and morphology of WMTA was finer compared to CEM 1 and CEM 2. The three tested materials had relatively similar chemical composition and irregular particle morphologies. PMID:26830831

  6. Study on the hydration and microstructure of Portland cement containing diethanol-isopropanolamine

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Suhua, E-mail: yc982@163.com; Li, Weifeng; Zhang, Shenbiao; Hu, Yueyang; Shen, Xiaodong

    2015-01-15

    Diethanol-isopropanolamine (DEIPA) is a tertiary alkanolamine used in the formulation of cement grinding-aid additives and concrete early-strength agents. In this research, isothermal calorimetry was used to study the hydration kinetics of Portland cement with DEIPA. A combination of X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC)–thermogravimetric (TG) analysis and micro-Raman spectroscopy was used to investigate the phase development in the process of hydration. Mercury intrusion porosimetry was used to study the pore size distribution and porosity. The results indicate that DEIPA promotes the formation of ettringite (AFt) and enhances the second hydration rate of the aluminate and ferrite phases, the transformation of AFt into monosulfoaluminate (AFm) and the formation of microcrystalline portlandite (CH) at early stages. At later stages, DEIPA accelerates the hydration of alite and reduces the pore size and porosity.

  7. 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.

  8. Analysis by X-Ray images of EVA waste incorporated in Portland Cement

    International Nuclear Information System (INIS)

    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)

  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. Remarks on durability of carbonated and uncarbonated Portland cement under sulphate action. Infrared spectroscopy study

    Directory of Open Access Journals (Sweden)

    Vázquez Moreno, T.

    1973-03-01

    Full Text Available Not availableAl objeto de poder comprobar y comparar los resultados obtenidos sobre una serie de ensayos de prismas pequeños (KOCH y STEINEGGER de 1 X 1 X 6 cm, hechos en colaboración con el "Subcomité de Resistencia Química" del CEMBUREAU, en el I.E.T.c.c. se realizaron tres nuevas series de ensayo con ocho cementos distintos, una de las cuales nos sirvió para estudiar el efecto inhibidor de la carbonatación. También sobre dos de estas series se ha efectuado un estudio de espectroscopia infrarroja, para un mejor esclarecimiento de la durabilidad del cemento portland frente a los sulfatos. En este artículo se resumen los resultados obtenidos, cuyo estudio completo saldrá en una próxima publicación del I.E.T.c.c.

  11. Durabilidad del hormigón frente al agua de mar. Estudio de dos cementos portland

    Directory of Open Access Journals (Sweden)

    Gaspar-Tebar, Demetrio

    1977-06-01

    Full Text Available In the present paper, the behaviour is set forth of mortars (1:3 made with two types of Spanish portland cement which have a C3A content of under 8 and 5 %, respectively, against sea water. This gives the evolution of mechanical bending strengths, corrosion coefficients (Koch-Steinegger, as well as the variation in the ionic concentration of the Solutions in which the mortar specimens were submerged (filtered water and sea water during a 56-day period, the structural composition of the solid stage formed and the hydrated cement paste. On the other hand, a bibliographic survey is included on the durability of mortars and concretes against sea water.En el presente trabajo se da cuenta del comportamiento de los morteros (1 : 3 hechos con dos cementos portland españoles que tienen un contenido de C3A menor del 8 y del 5%, respectivamente, frente al agua de mar, determinando la evolución de las resistencias mecánicas a flexión, los coeficientes de corrosión (Koch-Steinegger, así como la variación de la concentración iónica de las disoluciones en donde se han sumergido las probetas de mortero (agua filtrada y agua de mar durante 56 días, la composición estructural de la fase sólida formada y de la pasta de cemento hidratado. Por otra parte, se incluye un estudio bibliográfico sobre la durabilidad de los morteros y hormigones frente al agua de mar.

  12. Mechanical characterization of Portland cement mortars containing petroleum or coal tar

    Directory of Open Access Journals (Sweden)

    Garcés, P.

    2007-08-01

    Full Text Available This article discusses experimental data on the flexural and compressive strength of Portland cement mortars containing additions or cement replacements consisting in petroleum or coal tar, by-products of the oil and coal industries. The materials studied were two coal (BACA and BACB and two petroleum (BPP and BPT tars. The results show that it is feasible to use such materials as a partial replacement for cement in mortar manufacture. This should lead to the design of a new sustainable product that will contribute to lowering the environmental impact of construction materials while at the same time opening up an avenue for the re-use of this type of industrial by-products.En este artículo se presentan datos experimentales de resistencia a flexión y a compresión de morteros de cemento Portland con adición y sustitución de breas de petróleo y de alquitrán de carbón, que son subproductos de la industria del carbón o del petróleo. Los materiales estudiados son breas de alquitrán de carbón A (BACA y B (BACB, y dos breas de petróleo (BPP y (BPT. Los datos demuestran la viabilidad del uso de estas breas en la fabricación de morteros con menores contenidos de cemento, permitiendo diseñar un nuevo material sostenible con el medio ambiente y que contribuya a reducir el impacto ambiental de los materiales de construcción, hecho que permite abrir una nueva vía de valorización de estos subproductos.

  13. 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.

  14. 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. PMID:25966327

  15. Immobilisation of strontium, nickel and iodide by a sulphate-resisting Portland cement

    International Nuclear Information System (INIS)

    The interaction of Sr(II), Ni(II) and I(-I) with sulphate-resisting Portland cement was investigated under highly alkaline conditions. Batch-sorption studies were performed by contacting HTS cement (haute teneur en silice, sulphate-resisting Portland cement, Lafarge, France) with artificial cement pore water (ACW). The composition of ACW was 0.18 M KOH, 0.114 M NaOH and 1.2 mM Ca(OH)2. 85Sr, 63Ni and 125I were used as tracers. In the experiments with Sr(II) and Ni(II), isosaccharinic acid (ISA) was added to ACW at 10-5 M to 10-2 M in order to study the effect of complexing ligands on radionuclide retention. The stability of the tracer solutions and the cement suspensions were first assessed. Moreover, the inventory of the stable elements were determined in cement and cement pore water. We then studied the kinetics of the radionuclide-cement interaction process and measured the dependence of the distribution ratio (Rd) on the concentration of ISA and on the concentration of cement particles (S:L ratio). In the case of 63Ni and 125I a strong decrease in the distribution ratio (Rd) with increasing S:L ratio was observed. There is strong indication that the inventory of the stable fraction of an element present in cement pore water accounts for the retention of the radioisotope fraction. The results further indicate that phase transformations may occur in non-pre-equilibrated cement systems (non-equilibrium conditions) which affect 63Ni uptake by HTS cement. The distribution ratios measured on HTS cement were compared with values obtained from measurements on important cement components (portlandite, CSH/C(A)SH-phases)

  16. 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.

  17. Hydration kinetics for the alite, belite, and calcium aluminate phase in Portland cements from 27Al and 29Si MAS NMR spectroscopy

    DEFF Research Database (Denmark)

    Skibsted, Jørgen; Jensen, Ole Mejlhede; Jakobsen, Hans Jørgen

    1997-01-01

    29Si magic-angle spinning (MAS) NMR spectroscopy is shown to be a valuable tool for obtaining the quantities of alite and belite in hydrated Portland cements. The hydration (1-180 days) of a white Portland cement with 10 wt.% silica fume added is investigated and the degrees of hydration for alit...... belite, and silica fume are determined. It is demonstrated that 27Al MAS NMR spectra of hydrated Portland cements can give quantitative information about the formation of ettringite and the conversion of this phase to monosulphate during hydration....

  18. Características da sílica coloidal e seus efeitos em concretos refratários Characteristics of colloidal silica and its effects on refractory castables

    OpenAIRE

    M. V. M. Magliano; V. C. Pandolfelli

    2010-01-01

    A sílica coloidal se apresenta como um promissor substituto do cimento de aluminato de cálcio para utilização em concretos mulitizáveis. O uso deste ligante promove adequada resistência mecânica a verde, facilidade de secagem, inibe a formação de fases de baixo ponto de fusão, além de favorecer a formação de mulita in-situ. Entretanto, as propriedades finais do concreto dependem das características da solução coloidal utilizada. O objetivo deste trabalho é comparar as propriedades a verde e a...

  19. Aspectos do coprocessamento de resíduos em fornos de clínquer Aspects of waste co-processing in clinker kilns

    Directory of Open Access Journals (Sweden)

    Sônia Denise Ferreira Rocha

    2011-03-01

    Full Text Available A prática do coprocessamento de resíduos na indústria de cimento tem se expandido devido à necessidade crescente de uma destinação ambiental e socialmente mais adequada de resíduos perigosos provenientes de diversos processos industriais. O objetivo deste trabalho foi realizar uma revisão sobre o coprocessamento de resíduos em fornos de clínquer, no Brasil e no mundo, visando contribuir para a otimização dos processos, identificando os aspectos já estudados e os que ainda demandam pesquisas. Foram abordados aspectos socioambientais e tecnológicos do coprocessamento, bem como a análise do ciclo de vida (ACV na produção de cimento, e a produção técnico-científica sobre o coprocessamento.The practice of co-processing of residues has increased due to the requirement of environmental and social friendly disposal of dangerous wastes from several industrial processes. The aim of this work was to perform a revision of co-processing of residues in Brazil and in the world, aiming at process optimization and also to identify the aspects already studied as well as those which still request research efforts. Social, environmental, and technological aspects of co-processing were discussed in the present work as well as the life cycle analysis (LCA in the cement production and the technical and scientific literature about co-processing.

  20. 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

  1. 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

  2. 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

  3. Hydration and microstructure of Portland cement partially substituted with ultrafine silica

    Directory of Open Access Journals (Sweden)

    Escalante, J. I.

    2009-12-01

    Full Text Available Geothermal waste, a by-product of steam power plants that use geothermal underground resources, was studied as a possible replacement for Portland cement. This waste consists primarily in amorphous nanometric silica with traces of sodium and potassium chlorides. The replacement ratios studied were 0, 10 and 20% in cements cured at 20 and 60 ºC. X-ray diffraction analysis showed that clinker phase hydration took place earlier in the presence of the geothermal waste. Scanning electron microscopy, in turn, revealed a reduction in porosity and intense calcium hydroxide consumption as a result of the pozzolanic reaction. The pastes containing 20% waste, however, an intense cracking was observed due to the formation of alkali silica reaction gel and ettringite. Cracking was more prominent at 60 ºC but was not observed in either the neat cement or the blend with 10 % waste. The presence of these detrimental phases was attributed to the formation of Friedel’s salt in the initial hydration stages, induced by the chlorides in the geothermal material.Se investigaron pastas de cemento Portland sustituido con un desecho geotérmico, subproducto de la generación de electricidad en plantas que emplean recursos geotérmicos. El desecho está compuesto principalmente de sílice amorfa de tamaño nanométrico, con cloruros de sodio y potasio. Se investigaron cementos con niveles de substitución de 0, 10 y 20%, curados a 20 y 60 °C. En presencia del desecho geotérmico, se observó por Difracción de rayos X cuantitativa que la hidratación de las fases del clínker se aceleró; además mediante microscopía electrónica de barrido se encontró una disminución en la porosidad y un intenso consumo de hidróxido de calcio por la reacción puzolánica. Sin embargo, para pastas con 20% de desecho geotérmico, se observó agrietamiento con la presencia de gel de reacción álcali sílice y ettringita; fue más acentuado a 60 °C y no se observó para pastas de

  4. 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

  5. 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

  6. Influence of The Activated Qatari Attapulgite Clay Admixture on The Mechanical Properties and Hydration Kinetics of Ordinary Portland Cement

    OpenAIRE

    Al-Noaimi, Kawkab Kh. [كوكب النعيمي

    2001-01-01

    Blended cements are types of cements containing additives other than those used m Portland cement, which have considerable technological interest, because such addition increases the chemical resistance to sulfate and chloride attack. The present investigation represents a laboratory study, which provides a unique opportunity to introduce an effective practical attempt to deal with the problem of concrete deterioration m Qatar and the Arabian Gulf region, and to provide a solution to the prob...

  7. Microstructure and Engineering Properties of Alkali Activated Fly Ash -as an environment friendly alternative to Portland cement

    OpenAIRE

    Ma, Y.

    2013-01-01

    Alkali activated fly ash (AAFA), also named “geopolymer”, has emerged as a novel engineering material in the construction industry. This material is normally formed by the reaction between fly ash and aqueous hydroxide or alkali silicate solution. With proper mix design, AAFA can present comparable or superior engineering properties to Portland cement. Moreover, this material shows great potential for sustainable development since its production has a significantly lower CO2 emission than the...

  8. A review of the methods used to study biocompatibility of Portland cement-derived materials used in dentistry

    OpenAIRE

    Camilleri, Josette

    2006-01-01

    Advanced restorative dentistry may necessitate the need for surgical intervention to the infected root apex. Once access to the root end is achieved, the root apex is resected and filled with a dental restorative material. The materials currently in use are not satisfactory due to inadequate biocompatibility and failure to achieve desirable properties in an aqueous environment. With the introduction of a new material, essentially Portland cement used in the building industry, these desirable ...

  9. ENERGY, ACOUSTICS AND ENVIRONMENTAL SUSTAINABILITY ANALYSIS OF BUILDING SYSTEMS BASED ON WOOD WOOL MINERALIZED WITH PORTLAND CEMENT

    OpenAIRE

    Pavarin, Cora

    2014-01-01

    In the present work various aspects of the energetic, thermal and acoustic properties of porous materials with wood wool mineralized Portland cement have been analyzed, in cooperation with the company Celenit Srl, a manufacturer of panels for building insulation. These products are also recognized interesting and desirable for their environmental sustainability through specific certifications. Remind that sustainability means "development that meets the needs of the present without comprom...

  10. In vitro sealing ability of white and gray mineral trioxide aggregate (MTA and white Portland cement used as apical plugs

    Directory of Open Access Journals (Sweden)

    Patrícia Zanatta Aranha Coneglian

    2007-06-01

    Full Text Available This study evaluated the sealing ability of apical plugs made of white and gray MTA-Angelus® and white Portland cement placed via the root canal and having different thicknesses (2, 5 and 7 mm. Ninety extracted human single-rooted teeth were instrumented using a size 40 K-file to standardize the foraminal opening by the stepback technique. The teeth were assigned to 3 groups (n=30, according to the material used for fabrication of the apical plugs: A = gray MTA; B = white MTA; C = white Portland cement. The groups were subdivided into groups of 10 teeth each according to the apical plug thickness (2, 5 and 7 mm. Marginal apical dye leakage was assessed using 0.2% Rhodamine B solution in which the specimens were immersed for 72 hours at 37ºC. The roots were sectioned longitudinally in a buccolingual direction for apical plug exposure, and digital photographs were taken and analyzed by Image Tool image-analysis software. Data were analyzed statistically by Kruskal-Wallis and Dunn's tests. Significance level was set at 5%. The least percent leakage was observed for 5- and 7-mm-thick plugs (p0.05 was found between gray MTA and white Portland cement. Among the three materials analyzed, white MTA presented the highest marginal leakage (p<0.05. The findings of the present study showed that gray MTA and Portland cement had better sealing ability than white MTA when used as apical plugs. Dye leakage was smaller for 5- and 7-mm-thick plugs compared to 2-mm-thick plugs.

  11. El cemento portland en la consistencia del hormigón fresco. Finura de molido óptima

    Directory of Open Access Journals (Sweden)

    Sabesinsky Felperin, M.

    1977-03-01

    Full Text Available En el presente trabajo, se investiga en micro-hormigones frescos preparados con esqueletos granulares compactos y agregados normales, la influencia de la finura de molido del cemento portland en la consistencia del cuerpo compuesto fresco, de distintas relaciones agua/cemento. La relación agua/cemento de la pasta conglomerante y la finura de molido del cemento portland componente de la misma, gobiernan las propiedades del hormigón fresco. Para una determinada consistencia puede establecerse "una finura de molido óptima del cemento portland", la cual permite reducir a un mínimo los requerimientos de agua de amasado. Estimando la finura de molido por mediciones de superficie específica puede establecerse que, para consistencias del hormigón fresco dentro del rango plástico, la superficie específica óptima corresponde a valores entre 2.900 y 3.060 cm2/g (BLAINE.

  12. Microbial dechlorination of polychlorinated biphenyls, dibenzo-p-dioxins, and -furans at the Portland Harbor Superfund site, Oregon, USA.

    Science.gov (United States)

    Rodenburg, Lisa A; Krumins, Valdis; Curran, Joanna Crowe

    2015-06-16

    The Portland Harbor (Oregon, USA) has been declared a "Superfund" site because it is impacted by a variety of contaminants, including polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs). Using data collected in the remedial investigation, concentrations of PCBs and PCDD/Fs in sediment and water were examined using positive matrix factorization to look for evidence that PCBs and PCDD/Fs are dechlorinated by anaerobic bacteria. This process has long been known to occur in sediments. Recently, it has been recognized that PCB and PCDD/F dechlorination may also occur in other anaerobic environments, such as in landfills, sewers, and groundwater. The results indicate that a factor related to the dechlorination of PCBs and PCDD/Fs was present in the water but not in the sediment. Spatial patterns in dechlorination products suggest that they come primarily from groundwater. Dechlorination products comprise 22% of the PCBs in the water. The Portland Harbor therefore represents the third major US watershed in which PCBs appear to undergo dechlorination in an environment other than sediment, suggesting that the microbial dechlorination of PCBs and PCDD/Fs is more common than previously assumed. In addition, the Portland Harbor is impacted by PCBs generated inadvertently during the production of pigments, such as PCB 11, which alone exceeded the 64 pg/L federal water quality standard for the sum of PCBs in two of 120 whole water samples. PMID:26010118

  13. 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.

  14. Estudo comparativo da infiltração marginal em restaurações de classe V

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    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.

  15. 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.

  16. The chemistry and expansion of limestone - Portland cement mortars exposed to sulphate containing solutions

    International Nuclear Information System (INIS)

    Some concretes in sulphate-bearing groundwaters can deteriorate slowly through chemical reactions which cause expansion and stress. The overall process involves diffusion of sulphate into the concrete, chemical reaction with some cement constituents, internal expansion and, finally, physical disruption of the reacted zone. This work addresses the chemical reactions and the expansion resulting from them so that the overall process of sulphate attack can be modelled eventually. The extent and rate of reaction of calcium sulphate with ordinary and sulphate resisting Portland cements (OPC and SRPC) have been measured under various conditions. Additionally, mortar bars were fabricated from OPC, OPC/BFS (blast furnace slag) and SRPC cements with carboniferous limestone and exposed to various sulphate-containing solutions. The linear expansion of the bars was continuously monitored over a period of about 200 days and, after exposure, the bars were analysed in detail. The results show that the bulk expansion during sulphate attack is proportional to sulphur taken up in insoluble ettringite and magnesium (when present) precipitated as brucite. The results are used to rationalise the behaviour of concretes in sulphate-bearing environments. (author)

  17. Increase in the strength characteristics of Portland cement due to introduction of the compound mineral supplements

    Science.gov (United States)

    Il'ina, Liliia; Gichko, Nikolai; Mukhina, Irina

    2016-01-01

    At the initial phase of hardening it is the limestone component that plays a major role in the hardening process, which acts as the substrate for the crystallization of hydrate tumors due to its chemical affinity with the products of Portland cement hydration. After 7 days, the diopside supplement influences the processes more significantly. Diopside has a high modulus of elasticity compared to the cement paste. As a result, stresses are redistributed within the cement paste and the whole composition is hardened. An increase in the quantity of diopside in the compound supplement to more than 66.7% does not provide a substantial increase in the strength of the cement paste. As the hardness of diopside is higher than the hardness of limestone, much more energy is required to grind it down to a usable component. Therefore, a further increase in the quantity of diopside in the compound supplement is not economically feasible. An evaluation of the optimum quantity of input compound mineral supplements can be made based on the ideas of close packing of spherical particles and the Pauling rules. The optimum content of the supplement is 8-8.5% provided that its dispersion and density are close to the dispersion and density of the binder. An increase in the dispersion of the supplement reduces its optimal quantity.

  18. 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.

  19. 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.

  20. The impact of sulphate and magnesium on chloride binding in Portland cement paste

    International Nuclear Information System (INIS)

    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 MgCl2, NaCl, NaCl + MgCl2, MgSO4 + MgCl2 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

  1. Absorption Characteristics of Cement Combination Concrete Containing Portland Cement, fly ash, and Metakaolin

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    Folagbade S.O.

    2016-03-01

    Full Text Available The resistance to water penetration of cement combination concretes containing Portland cement (PC, fly ash (FA, and metakaolin (MK have been investigated at different water/cement (w/c ratios, 28-day strengths, and depths of water penetration using their material costs and embodied carbon-dioxide (eCO2 contents. Results revealed that, at equal w/c ratio, eCO2 content reduced with increasing content of FA and MK. MK contributed to the 28-day strengths more than FA. Compared with PC, FA reduced cost and increased the depth of water penetration, MK increased cost and reduced the depth of water penetration, and their ternary combinations become beneficial. At equal strengths and levels of resistance to water penetration, most of the cement combination concretes are more environmentally compatible and costlier than PC concrete. Only MK binary cement concretes with 10%MK content or more and ternary cement concretes at a total replacement level of 55% with 10%MK content or more have higher resistance to water penetration than PC concrete.

  2. 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.

  3. Seawater Resistance Evaluation of Existing NPP Concrete Structures Using High-sulfate Resistance Portland Cement

    International Nuclear Information System (INIS)

    For nuclear power plant(NPP) structures exposed to marine environment, low-heat and high sulfate resistance portland cement(Type V) with low content of C3A has been widely used to restrain the occurrence of chemical erosion caused by seawater. Despite the superior sulfate resistance of Type V cement, however, questions have been raised on the efficiency of Type V cement for resisting the chloride ion, which is one of the major substances found in seawater. Accordingly, the ACI 357R revised in 1984 required that Type I or II cement containing 4 ∼ 10% of C3A be used. In addition, the standard specifications of Korea Concrete Institute (KCI) were revised in 1996 in order to limit the use of Type V cement in the construction of marine concrete structures. In this regard, the mechanical properties and seawater resistance of concrete using various kinds of cement have been studied to evaluate the durability of existing NPP structures using Type V cement as well as to manifest the regulatory position for the materials of concrete. This paper presents detail observations obtained through this study

  4. Nanostructural Deformation Analysis of Calcium Silicate Hydrate in Portland Cement Paste by Atomic Pair Distribution Function

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    Hiroshi Suzuki

    2016-01-01

    Full Text Available The deformation of nanostructure of calcium silicate hydrate (C-S-H in Portland cement (PC paste under compression was characterized by the atomic pair distribution function (PDF, measured using synchrotron X-ray diffraction. The PDF of the PC paste exhibited a unique deformation behavior for a short-range order below 2.0 nm, close to the size of the C-S-H globule, while the deformation for a long-range order was similar to that of a calcium hydroxide phase measured by Bragg peak shift. The compressive deformation of the C-S-H nanostructure was comprised of three stages with different interactions between globules. This behavior would originate from the granular nature of C-S-H, which deforms with increasing packing density by slipping the interfaces between globules, rearranging the overall C-S-H nanostructure. This new approach will lead to increasing applications of the PDF technique to understand the deformation mechanism of C-S-H in PC-based materials.

  5. Effect of temperature on the hydration of Portland cement blended with siliceous fly ash

    International Nuclear Information System (INIS)

    The effect of temperature on the hydration of Portland cement pastes blended with 50 wt.% of siliceous fly ash is investigated within a temperature range of 7 to 80 °C. The elevation of temperature accelerates both the hydration of OPC and fly ash. Due to the enhanced pozzolanic reaction of the fly ash, the change of the composition of the C–S–H and the pore solution towards lower Ca and higher Al and Si concentrations is shifted towards earlier hydration times. Above 50 °C, the reaction of fly ash also contributes to the formation of siliceous hydrogarnet. At 80 °C, ettringite and AFm are destabilised and the released sulphate is partially incorporated into the C–S–H. The observed changes of the phase assemblage in dependence of the temperature are confirmed by thermodynamic modelling. The increasingly heterogeneous microstructure at elevated temperatures shows an increased density of the C–S–H and a higher coarse porosity. -- Highlights: •The reaction of quartz powder at 80 °C strongly enhances the compressive strength. •Almost no strength increase of fly ash blended OPC at 80 °C was found after 2 days. •Siliceous hydrogarnet is formed upon the reaction of fly ash at high temperatures. •Temperature dependent change of the system was simulated by thermodynamic modelling. •Destabilisation of ettringite above 50 °C correlates with sulphate content of C–S–H

  6. Development of Portland cement for orthopedic applications, establishing injectability and decreasing setting times.

    Science.gov (United States)

    Wynn-Jones, Gareth; Shelton, Richard M; Hofmann, Michael P

    2012-11-01

    The injectability of Portland cement (PC) with calcium chloride and calcium nitrate additives was investigated using a syringe with a 2 mm aperture for potential clinical applications such as vertebroplasty. Addition of either additive at 10 wt % increased the quantity of cement extruded through the syringe from approximately 25 wt % for the PC standard, to over 95 wt %. 10 wt % additions of either additive also decreased setting times from over 2 h to below 25 min. The compressive strength of the modified cements was all greater than the compressive strength of a human vertebral body. Decreasing either additive to 5 wt % generated compressive strengths after 24 h setting equal to polymethylmethacrylate, the cement used for the majority of vertebroplasty procedures. An initial early exotherm in the chloride cements was coupled with an X-ray diffraction (XRD) peak that indicated the early formation of the ettringite cement phase. In contrast, Fourier transform infrared (FTIR) spectroscopy and XRD data indicated that calcium nitrate may have stimulated early calcium silicate hydrate (C-S-H) production (the main strength producing phase of PC). Combining the two additives produced a synergistic effect with cements having increased injectabilities and compressive strengths compared with either addition used individually. This study has demonstrated that by modifying PC with nonproprietary chemicals it was possible to significantly increase cement injectability and reduce setting times whilst maintaining compressive strengths, making PC suitable for potential orthopedic applications. PMID:22887643

  7. Effect of temperature on the hydration of Portland cement blended with siliceous fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Deschner, Florian, E-mail: florian.deschner@gmail.com [Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Concrete and Construction Chemistry, Überlandstrasse 129, 8600 Dübendorf (Switzerland); Lothenbach, Barbara; Winnefeld, Frank [Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Concrete and Construction Chemistry, Überlandstrasse 129, 8600 Dübendorf (Switzerland); Neubauer, Jürgen [GeoZentrum Nordbayern, Mineralogy, University of Erlangen-Nuremberg, 91054 Erlangen (Germany)

    2013-10-15

    The effect of temperature on the hydration of Portland cement pastes blended with 50 wt.% of siliceous fly ash is investigated within a temperature range of 7 to 80 °C. The elevation of temperature accelerates both the hydration of OPC and fly ash. Due to the enhanced pozzolanic reaction of the fly ash, the change of the composition of the C–S–H and the pore solution towards lower Ca and higher Al and Si concentrations is shifted towards earlier hydration times. Above 50 °C, the reaction of fly ash also contributes to the formation of siliceous hydrogarnet. At 80 °C, ettringite and AFm are destabilised and the released sulphate is partially incorporated into the C–S–H. The observed changes of the phase assemblage in dependence of the temperature are confirmed by thermodynamic modelling. The increasingly heterogeneous microstructure at elevated temperatures shows an increased density of the C–S–H and a higher coarse porosity. -- Highlights: •The reaction of quartz powder at 80 °C strongly enhances the compressive strength. •Almost no strength increase of fly ash blended OPC at 80 °C was found after 2 days. •Siliceous hydrogarnet is formed upon the reaction of fly ash at high temperatures. •Temperature dependent change of the system was simulated by thermodynamic modelling. •Destabilisation of ettringite above 50 °C correlates with sulphate content of C–S–H.

  8. 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 ettringite (Ca(6)Al(2)(SeO(4))(3)(OH)(12).26H(2)O), respectively. PMID:19339110

  9. 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.

  10. Simultaneous Differential Scanning Calorimetry and Thermogravimetric Analysis of Portland Cement as a Function of Age

    Science.gov (United States)

    Trník, Anton; Scheinherrová, Lenka; Kulovaná, Tereza; Černý, Robert

    2016-01-01

    We study the hydration and pozzolanic reactions of an ordinary Portland cement as a function of age, using the differential scanning calorimetry and thermogravimetry. The measurements are done for 2 days, 7 days, 28 days, 90 days, 180 days, and 360 days cured samples in order to monitor the rate of hydration. The investigation is performed in the temperature range from 25° C to 1000° C with a heating rate 5° C {\\cdot} min^{-1} in an argon atmosphere. The temperature, enthalpy, and mass change during the decomposition of calcium silicate hydrate gels, ettringite, portlandite, vaterite, and calcite are determined, and the changes in the portlandite amount are estimated in dependence on the time of hydration. We found out that the temperature and enthalpy of liberation of physically bound water, C-S-H gels and ettringite decomposition (all occurring from 50° C to 250° C) and Portlandite decomposition (420° C to 530° C) decrease with hydration time of studied samples. On the other hand, vaterite and calcite decomposition (530° C to 850° C) the temperature varies and the enthalpy increases with hydration time of samples.

  11. 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.

  12. Setting temperature evolution of nitrate radwaste immobilized in ordinary portland cement

    International Nuclear Information System (INIS)

    Materials based on hydraulic cements such as ordinary Portland cement (OPC) have many applications in the radioactive waste disposal field. Cement hydration process is an exothermic reaction and can cause a considerable temperature rise in the cemented waste form. Specially when large blocks of waste forms are produced it is necessary to have some information about the temperature build up which occurs inside the mass, because this effect may have some influences on the ultimate properties of the hardened cement paste. This temperature rise cause expansion while the cement paste is hardening. When the cooling process takes place, to the surrounding temperature, crackings and contractions may then occur. Whether cracking arise it depends both on the magnitude of the temperature induced stress and on the capacity of the mixture to accommodate the strain. This paper compares the temperature growth in pastes into two different geometries: one uses a waste container with 3.8 dm3 (one US gallon) capacity placed inside a 0.21 m3 (55 gallons) concrete lined drum, which acts as a radiation shielding, and the other the same container placed in ambient at room temperature. Correlations between the time of temperature occurrence, maximum temperature, the water to cement ratio and salt content were observed

  13. DURABILITY PERFORMANCE OF RFCC SPENT CATALYSTBLENDED PORTLAND CEMENT PASTE EXPOSED TO SEA WATER ATTACK

    Directory of Open Access Journals (Sweden)

    Allahverdi A.

    2013-12-01

    Full Text Available This paper discusses the performance of the paste of Portland cement blended with spent catalyst from Resid Fluidized Catalytic Cracking (RFCC unit of petroleum refining processes in sea water. 28-day cured paste specimens prepared from binary cement mixes containing different amounts of spent catalyst were exposed to Persian Gulf sea water. Compressive strength, weight, and length changes of the specimens were monitored and considered for evaluating the extent of deterioration. Laboratory techniques of X-ray diffractometry, scanning electron microscopy, and Energy dispersive X-ray spectroscopy were also used to study the deteriorated specimens. The results confirm that at relatively high replacement levels, the pozzolanic property of the spent catalyst and the increased open pore volume of such blended cements may result in contradictory consequences. Specimens of relatively higher replacement levels exhibit higher rates of deterioration in spite of their superior mechanical strength behavior caused by pozzolanic reaction. The results obtained by X-ray diffractometry confirm the presence of higher amounts of chlorine-containing Friedel’s salt in specimens containing RFCC spent catalyst compared to plain reference specimens.

  14. Solidification of spent radioactive organic solvent by sulfoaluminate and Portland cements

    International Nuclear Information System (INIS)

    The solidification of simulated spent radioactive organic solvent, tri-butyl phosphate/kerosene, was investigated by emulsification–solidification method using sulfoaluminate cement (SAC) and Portland cement (PC). Zeolite, calcium hydroxide and MR-1 type emulsifier were mixed into the cement blends for improving the performance of solidified waste forms (SWF). The properties of SWF were evaluated in terms of mechanical strength, leachability and mineral phase analyses. The hydration products of SWF were characterized by X-ray diffraction (XRD). The experimental results showed that the 28 d compressive strengths of SAC solidified waste forms (SACF) and PC solidified waste forms (PCF) were 14.23 and 19.07 MPa, respectively. Leaching sequence of three radionuclides in two kinds of SWF is Cs+ > Sr2+ > Co2+. Compared with PCF, SACF had better performance in preventing nuclides Co2+ and Cs+ from leaching to the environment. The XRD patterns suggested that simulated spent radioactive organic solvent and emulsifier in SWF did not obviously change the hydration products of the two cements (SAC and PC). (author)

  15. Using portland cement for encapsulation of epipremnum aureum generated from phytoremediation process of liquid radioactive wastes

    International Nuclear Information System (INIS)

    Phyto remediation process was recommended for treatment of low and intermediate level liquid radioactive waste. Epipremnum aureum (golden pothas plant) was used to bioabsorbe, bioaccumulate and biostabilize Cs-137 and Co-60 from simulated waste solution containing both radionuclides. After the phyto remediation process, the collected golden pothas was solidified using portland cement aiming at complete and safe management scheme. In this part of work x-ray diffraction , infrared analysis and electron microscope examination as non-destructive techniques were used to evaluate the characteristics of obtained final waste forms of cemented golden pothas. In addition, mechanical, porosity and chemical optimizations were performed under various experimental parameters to asses the suitability of the two processes i.e. phyto remediation and cementation for managing these wastes categories. The experimental results obtained confirmed that encapsulation of 3 % dry ground golden pothas that collected from treatment process of radioactive waste solution, in cement materials did not affect the hydration, setting and curing of the cement matrix. In addition , the obtained cemented waste form exhibits acceptable constitutions that comply with the final disposal requirements.

  16. 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. PMID:23864828

  17. 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.

  18. Reactivity of Ordinary Portland Cement (OPC) grout and various lithologies from the Harwell research site

    International Nuclear Information System (INIS)

    Ordinary Portland Cement (OPC) has been used in the completion of boreholes on the Harwell Research Site, AERE, Oxfordshire. The purpose of this study was to examine the effect of OPC and the alkaline pore fluids generated during its setting on the various lithological types encountered in the boreholes. To facilitate this, samples of core representing the various rock types were selected and cement-rock composites were prepared from these in the laboratory to simulate the borehole cements. After a curing period of 15 months the cores and associated cement plugs were examined for any signs of reactivity or bonding. The best cement-rock bonding was shown by naturally well-cemented sandstone and limestone lithologies. Although no significant chemical reaction was seen to have occurred between OPC and rock, the OPC appears able to bind onto the rock surface because of the rigidity of the rock surface. Therefore, the best cement rock bonding and seal with OPC may be expected in the limestones of the Great Oolite Group, Inferior Oolite Group and parts of the Corallian Beds. Because of the reactivity of OPC towards certain lithologies a better borehole seal in such a sedimentary sequence might be achieved using a bentonite backfill in those parts of the sequence which either react with or bond only weakly to OPC. (author)

  19. Some aspects about the Portland cement utilization as a matrix for radioactive waste immobilization

    International Nuclear Information System (INIS)

    More recently, the environmental policy has concentrated the focus on the study of the waste disposal environmental impact. Since Portland cement is commonly used as a matrix in the low-and intermediate-level radioactive waste immobilization, in the present work, some relationships between the structure and properties of matrix, based on available concrete technology information, has been established by using the multi-level approach analysis. The relationships were developed based on hydrating reactions, the microstructure models, the pore system. It have been verified that: a) CSH gel is responsible for the cementing action and for the strength; b) it seems that the capillary porosity is the strength limiting; c) the permeability, regarded in terms of gel porosity and reduced capillary porosity of the hardened cement paste, may not be a decisive factor for the radionuclide release; d) the shrinkage and the swelling induced cracks can enhance the diffusion mechanism for the cracks increase the exposed surface. The durability of the waste disposal matrix concerning chemical attack in the acidic environment has been considered. (author)

  20. 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.

  1. Analysis of Metal Contents in Portland Type V and MTA-Based Cements

    Directory of Open Access Journals (Sweden)

    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.

  2. 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.

  3. Evaluation of Portland cement from X-ray diffraction associated with cluster analysis

    International Nuclear Information System (INIS)

    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)

  4. 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.

  5. Estudo da estabilidade dos componentes na artroplastia total do joelho sem cimento Study on implant stability in cementless total knee arthroplasty

    Directory of Open Access Journals (Sweden)

    Luís Eduardo Passarelli Tírico

    2012-01-01

    Full Text Available OBJETIVO: Comparar dois métodos de avaliação da estabilidade dos componentes tibial e femoral nas artroplastias de joelho não cimentadas com plataforma rotatória. MÉTODOS: Para isso foram avaliados 20 pacientes (20 joelhos através de uma análise de radiografias dinâmicas com intensificador de imagem e manobras de estresse em varo e valgo, que foram comparadas com radiografias estáticas em frente e perfil dos joelhos, analisadas por dois cirurgiões experientes, cegos um em relação ao outro. RESULTADOS: Os resultados das análises estáticas e dinâmicas foram comparados e demonstraram forte correlação estatística (pObjetives: Determine the stability of tibial and femoral components of 20 cementless knee arthroplasties with rotating platform. METHODS: The 20 patients (20 knees underwent an analysis of dynamic radiographs with an image amplifier and maneuvers of varus and valgus which were compared to static frontal and lateral radiographs of the knees and analyzed by two experienced surgeons in a double-blind way. RESULTS: We could observe in this study that both methods showed very similar results for the stability of the tibial and femoral components (p<0,001 using the Kappa method for comparison. CONCLUSION: The tibial component was more unstable in relation to the femoral component in both static and dynamic studies. Level of evidence IV, Case Series.

  6. 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.

  7. 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

  8. 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

  9. 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.

  10. Synthesis, Crystal Structure and Luminescent Property of Cd (II Complex with <em>N-Benzenesulphonyl-L>-leucine

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    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.

  11. 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.

  12. Multiple determinations of isotope diffusion in cementitious backfills and Ordinary Portland Cement (OPC) monoliths

    International Nuclear Information System (INIS)

    The full text of publication follows: The UK concept for geological disposal of intermediate level (ILW) and low level waste (LLW) includes backfill materials based on admixtures of Ordinary Portland Cement (OPC). It is expected that the evolution of these backfill materials will generate high pH conditions and the corrosion of the metal canisters used for disposal will promote a low Eh environment. This combination of conditions within the near field of the Geological Disposal Facility (GDF) will reduce the solubility of many radionuclides and retard migration. In addition, sorption to some of the cementitious phases may contribute significantly to the retardation of many radionuclides. It is clearly important to understand how diffusion of radionuclides contributes to the overall migration from the repository. However, it remains practically difficult to isolate the effect of diffusion from other processes such as sorption and advection which may also occur in the near field and far fields of the GDF. This presentation describes a series of experiments undertaken to evaluate the diffusion of a selection of relevant radionuclides in saturated backfills (including the NIREX reference vault backfill, NRVB) and OPC matrices. The experiments build upon a significant number of related sorption studies previously undertaken by the radiochemistry group at Loughborough University and complement a series of small scale advection experiments also being undertaken. The experimental technique uses small pre-cast blocks (monoliths) of the matrix under investigation. An appropriate concentration of the isotope of interest is introduced in a cavity in the centre of the block, which is then sealed, and finally, placed in a solution previously equilibrated with the matrix. The increase in concentration of the isotope in the external solution is then determined at defined time intervals. The interpretation of the results is undertaken with methods conventionally used for geological

  13. Individual and combined effects of chloride, sulfate, and magnesium ions on hydrated Portland-cement paste

    International Nuclear Information System (INIS)

    Ground water with a high concentration of magnesium ion is known to cause deterioration to portland cement concretes. A proposed mechanism for this deterioration process published previously involves an approximate 1:1 replacement of Ca ions by Mg ions in the crystalline phases of hydrated cement. The current study was undertaken to determine which ions, among magnesium, chloride, and sulfate, cause deterioration; whether their deleterious action is individual or interdependent; and to relate this mechanism of deterioration to the outlook for a 100-yr service life of concretes used in mass placements at the Waste Isolation Pilot Plant. Loss of Ca ion by cement pastes was found to be strongly related to the concentration of Mg ion in simulated ground-water solutions in which the paste samples were aged. This was true of both salt- containing and conventional cement pastes. No other ion in the solutions exerted a strong effect on Ca loss. Ca ion left first from calcium hydroxide in the pastes, depleting all calcium hydroxide by 60 days. Some calcium silicate hydrate remained even after 90 days in the solutions with the highest concentration of Mg ion, while the paste samples deteriorated noticeably. The results indicated a mechanism that involves dissolution of Ca phases and transport of Ca ions to the surface of the sample, followed by formation of Mg-bearing phases at this reaction surface rather than directly by substitution within the microstructure of hydrated cement. Given that calcium hydroxide and calcium silicate hydrate are the principal strength-giving phases of hydrated cement, this mechanism indicates the likelihood of significant loss of integrity of a concrete exposed to Mg-bearing ground water at the WIPP. The rate of deterioration ultimately will depend on Mg-ion concentration, the microstructure materials of the concrete exposed to that groundwater, and the availability of brine

  14. Incorporation of trace elements in Portland cement clinker: Thresholds limits for Cu, Ni, Sn or Zn

    International Nuclear Information System (INIS)

    This paper aims at defining precisely, the threshold limits for several trace elements (Cu, Ni, Sn or Zn) which correspond to the maximum amount that could be incorporated into a standard clinker whilst reaching the limit of solid solution of its four major phases (C3S, C2S, C3A and C4AF). These threshold limits were investigated through laboratory synthesised clinkers that were mainly studied by X-ray Diffraction and Scanning Electron Microscopy. The reference clinker was close to a typical Portland clinker (65% C3S, 18% C2S, 8% C3A and 8% C4AF). The threshold limits for Cu, Ni, Zn and Sn are quite high with respect to the current contents in clinker and were respectively equal to 0.35, 0.5, 0.7 and 1 wt.%. It appeared that beyond the defined threshold limits, trace elements had different behaviours. Ni was associated with Mg as a magnesium nickel oxide (MgNiO2) and Sn reacted with lime to form a calcium stannate (Ca2SnO4). Cu changed the crystallisation process and affected therefore the formation of C3S. Indeed a high content of Cu in clinker led to the decomposition of C3S into C2S and of free lime. Zn, in turn, affected the formation of C3A. Ca6Zn3Al4O15 was formed whilst a tremendous reduction of C3A content was identified. The reactivity of cements made with the clinkers at the threshold limits was followed by calorimetry and compressive strength measurements on cement paste. The results revealed that the doped cements were at least as reactive as the reference cement.

  15. Progress in the investigation of the longevity of Portland cement grout seal materials

    International Nuclear Information System (INIS)

    The sealing of openings in underground repositories and the assessment of the potential for seal materials to perform acceptably for long periods of time are concerns shared by programs considering the deep disposal of nuclear waste. Two grouting materials, bentonite and portland cement, have been identified by many programs as likely candidate seal materials. As a part of Phase III of the Stripa Project, the longevity of both of these materials is being investigated in a series of coordinated laboratory, modeling, and field studies. Long-term performance is an important issue particularly for cement, since most solid phases in cement are metastable, and therefore it is likely that cement seal performance would degrade with time. In this investigation, geochemical and permeability modeling have been used together to estimate how long cement seals may be expected to perform acceptably. Analyses to assess cement degradation due to phase inversion and dissolution have been performed; for dissolution calculations, both slow flow and fast flow hydrologic systems have been analyzed to establish bounding conditions. Actual granitic terrain grounwater compositions ranging from fresh to saline have been used to calculate cement-groundwater interactions. A relationship between cement permeability and porosity has been developed based on empirical data. Changes in performance with time have been predicted by conservatively estimating hydrologic conditions at successive stages of post-closure repository history. For the conditions considered, preliminary results indicate that the single largest determinant of seal performance is the initial hydraulic conductivity of the cement. Based on this investigation, cement grout performance may be acceptable for very long periods of time (tens of thousands to millions of years) providing its initial conductivity is on the order of 10-12 m/s

  16. Factors associated with the uptake of cervical cancer screening among women in Portland, Jamaica

    Directory of Open Access Journals (Sweden)

    Butho Ncube

    2015-01-01

    Full Text Available Background: Cervical cancer is the second most common cancer among women worldwide and is the leading cause of deaths in developing countries. Despite the strong evidence that cervical cancer screening results in decreased mortality from this disease, the uptake for cervical screening among Jamaican women remains low. Aims : This study was carried out to identify factors associated with Jamaican women′s decisions to screen for cervical cancer. Materials and Methods: Cross-sectional descriptive study of 403 women aged 19 years and older from Portland, Jamaica. An interviewer-administered questionnaire assessed the women′s cervical cancer screening history, as well as their knowledge, attitudes, and practices regarding the disease and screening. Results: Of the 403 women interviewed, 66% had a Papanicolaou (Pap smear and only 16% had a Pap test within the past year. Significant predicators of uptake of screening were being married, age, parity, discussing cancer with health provider, perception of consequences of not having a Pap smear, and knowing a person with cervical cancer. Women who did not know where to go for a Pap smear were 85% less likely to have been screened (prevalence odds ratio (POR: 0.15, 95% confidence interval (CI: 0.04, 0.52. Conclusions: This study showed suboptimal uptake of cervical cancer screening among Jamaican women. Multipronged approaches are needed to address barriers to screening, as well as identify and support conditions that encourage women′s use of reproductive health services, thereby reducing incidence and mortality rates from cervical cancer.

  17. Permeability predictions for sand-clogged Portland cement pervious concrete pavement systems.

    Science.gov (United States)

    Haselbach, Liv M; Valavala, Srinivas; Montes, Felipe

    2006-10-01

    Pervious concrete is an alternative paving surface that can be used to reduce the nonpoint source pollution effects of stormwater runoff from paved surfaces such as roadways and parking lots by allowing some of the rainfall to permeate into the ground below. This infiltration rate may be adversely affected by clogging of the system, particularly clogging or covering by sand in coastal areas. A theoretical relation was developed between the effective permeability of a sand-clogged pervious concrete block, the permeability of sand, and the porosity of the unclogged block. Permeabilities were then measured for Portland cement pervious concrete systems fully covered with extra fine sand in a flume using simulated rainfalls. The experimental results correlated well with the theoretical calculated permeability of the pervious concrete system for pervious concrete systems fully covered on the surface with sand. Two different slopes (2% and 10%) were used. Rainfall rates were simulated for the combination of direct rainfall (passive runoff) and for additional stormwater runoff from adjacent areas (active runoff). A typical pervious concrete block will allow water to pass through at flow rates greater than 0.2 cm/s and a typical extra fine sand will have a permeability of approximately 0.02 cm/s. The limit of the system with complete sand coverage resulted in an effective system permeability of approximately 0.004 cm/s which is similar to the rainfall intensity of a 30 min duration, 100-year frequency event in the southeastern United States. The results obtained are important in designing and evaluating pervious concrete as a paving surface within watershed management systems for controlling the quantity of runoff. PMID:16563606

  18. Degradation of normal portland and slag cement concrete under load, due to reinforcement corrosion

    International Nuclear Information System (INIS)

    The corrosion of reinforcement is one of the major degradation mechanisms of reinforced concrete elements. The majority of studies published on concrete-steel corrosion have been conducted on unstressed specimens. Structural concrete, however, is subjected to substantial strain near the steel reinforcing bars that resist tensile loads, which results in a system of microcracks. This report presents the initial results of an investigation to determine the effect of applied load and microcracking on the rate of ingress of chloride ion and corrosion of steel in concrete. Simply-supported concrete beam specimens were loaded to give a maximum strain of about 600 με on the tension face. Chloride ion ingress on cores taken from loaded specimens was monitored using energy-dispersive X-ray analysis techniques. Corrosion current and rate measurements using linear polarization electrochemical techniques were also obtained on the same loaded specimens. Variables investigated included two concrete types, two steel cover-depths, three applied load levels, bonded and unbonded rebars and the exposure of tension and compression beam faces to chloride solution. One concrete mixture was made with type 10 Portland cement, the other with 75% blast furnace slag, 22% type 50 cement and 3% silica fume. The rate of chloride ion ingress into reinforced concrete, and hence the time for chloride ion to reach the reinforcing steel, is shown to be dependent on applied load and the concrete quality. The dependence of corrosion process descriptors - passive layer formation, initiation period and propagation period - on the level of applied load is discussed. (Author) (6 refs., 3 tabs., 10 figs.)

  19. Influence of Plasticizer Amount on Rheological and Hydration Properties of CEM II Type Portland Cements

    Science.gov (United States)

    Šeputytė-Juciké, J.; Pundienė, I.; Kičaitė, A.; Pranckevičienė, J.

    2015-11-01

    The article analyzes the effect of plasticizer (based on polycarboxilates) amount (0.3 - 1.2% wt. of cement) on the rheological and hydration properties of two Portland cements pastes: CEM II/A-S 42.5N and CEM II/A-LL 42.5N. Increase of plasticizer amount reduces viscosity of CEM II/A-LL 42.5N cement paste from 3 to 12 times, where viscosity of CEM II/A-S 42.5N cement paste reduces from 5 to 20 times. The optimum plasticizer dose (0.3%) in case of CEM II/A-S 42.5N and (1.2%) in case of CEM II/A-LL 42.5N was established. Calorimetry studies have shown that plasticizer reduces the wetting heat release rate in CEM II/A-LL 42.5N cement twice and in CEM II/A-S 42.5N cement - by 25%. Plasticizer prolongs the maximum heat release rate time by 16 h in CEM II/A-LL 42.5N samples and reduces heat release rate by 19%. In CEM II/A-S 42.5N cement samples plasticizer prolongs maximum heat release rate time by 14.5 h and increases heat release rate by 15%. The goal of this study is to analyze the effect of the dosage of the most widely used plasticizer on solubility characteristics, rheological and hydration properties of two cements CEM II/A-S 42.5N and CEM II/A-LL 42.5N to establish the optimum dose of plasticizer in cements pastes.

  20. 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.

  1. Chemical Composition and Microstructure of Hydration Products of Hardened White Portland Cement Pastes Containing Admixtures

    Institute of Scientific and Technical Information of China (English)

    LI Qiu

    2015-01-01

    This study investigated the nature of hydration products of white portland cement (WPC) containing 20 mM malic acid or 1 M calcium chloride hydrated for 11 years. The study identiifed the hydration products and characterized the chemical composition, morphology, micro/nano structure of C-S-H and the main binding phase in cementitious materials. Calcium hydroxide (CH), ettringite and C-S-H were identiifed in WPC with 20 mM malic acid paste hydrated for 11 years. WPC with 1 M calcium chloride paste hydrated for 11 years contained the same phases, but with less CH, and the presence of Friedel’s salt (Ca2Al(OH)6Cl·2H2O). There were still small amount of anhydrous cement particles remaining in both pastes after 11 years hydration according to the SEM and29Si MAS NMR results. The hydration products of paste containing malic acid had a lower porosity than those prepared with calcium chloride upon visual inspection under SEM. The morphology of the outer product (Op) C-S-H was coarse ifbrillar and the inner product (Ip) C-S-H had a very ifne microstructure in both pastes under TEM. Both Ip and Op C-S-H formed in paste containing malic acid had lower Ca/Si and higher Al/Si than those in paste containing calcium chloride. C-S-H in paste containing calcium chloride had longer MCL and less percentage of bridging tetrahedra occupied by aluminum in silicon/aluminum chains due to relatively lessQ1 and moreQ2. A new type of silicon tetrahedra,Q2B, was introduced during deconvolution of29Si MAS NMR results. Ip and Op C-S-H in both pastes had aluminum substituted tobermorite-type and jennite-type structure, and all the charges caused by aluminum substituting silicon bridging tetrahedra were balanced by Ca2+.

  2. Estimation of longevity of portland cement grout using chemical modeling techniques

    International Nuclear Information System (INIS)

    Portland cement has been identified as a likely candidate seal material by programs investigating the deep burial of nuclear waste as a disposal mechanism. The longevity of performance of cement grout is currently being investigated, along with bentonite, under the auspices of the Stripa Project. Coordinated laboratory, field, and modeling studies are underway to produce fundamental data, practical experience, and estimates of long-range performance, respectively. Long-term performance of cement grout is of particular concern. Since most of the solid phases of which grout is comprised are metastable, it is likely that grout performance will decrease with time. The question is whether performance will still be acceptable after this decrease. This issue is being addressed with the coupled use of geochemical and permeability modeling. For a simplified cement system, two mechanisms for chemical degradation have been considered: phase change and dissolution. For dissolution, both equilibrium (slow flow) and open (fast flow) systems have been analyzed as bounding scenarios. Granitic terrain groundwaters ranging from fresh to saline have been used in the analyses. To assess the consequences in terms of flow, an empirical relation between cement permeability and porosity has been developed. Performance changes with time have been predicted by making conservative estimates of local hydraulic head conditions for successive periods of repository history. For the granitic rock environments considered, preliminary results indicate that cement grout performance may be acceptable for tens of thousands to millions of years, providing its initial hydraulic conductivity is on the order of 10-12 m/s. Other conditions favoring long-term performance include minimizing the ettringite content of the grout, and emplacement at a site where the groundwater has an elevated TDS, and where the local hydraulic gradient is flat or repository resaturation times are short

  3. Effect of additives on the compressive strength and setting time of a Portland cement

    Directory of Open Access Journals (Sweden)

    Desirée Freitas Mryczka Machado

    2010-06-01

    Full Text Available Improvements in strength and setting time of Portland cements (PC are needed to enhance their performance as endodontic and load bearing materials. This study sought to enhance the compressive strength and setting time of a PC by adding one of the following additives: 20% and 30% poly-methylmethacrylate (PMMA, 20% and 30% irregular and spherical amalgam alloys, and 10% CaCl2. The control consisted of unreinforced PC specimens. Setting time was determined using a Gillmore apparatus according to standardized methods while compressive strength was measured using a universal testing machine after 21 hours or 60 days of water storage. Data were analyzed by ANOVA, Tukey and Games-Howell tests (α = 5%. All additives significantly decreased both initial and final setting times as compared with the PC-control (p < .05. 30% PMMA and 30% irregular alloy had the lowest values of initial setting time. 30% irregular alloy also produced the lowest values of final setting time while 30% spherical alloy yielded the highest (p < .05. No differences were detected between the compressive strength values of 21 hours and 60 days. While 10% CaCl2, 20% and 30% PMMA produced values significantly lower than the PC-control, 30% spherical alloy significantly improved the compressive strength of the reinforced PC (p < .05. In summary, all additives significantly reduced the setting time and 30% spherical amalgam alloy yielded a significant increase in compressive strength for the tested PC, which might represent an improved composition for PCs to expand their use as endodontic and potentially load bearing materials.

  4. Enhancement of cemented waste forms by supercritical CO{sub 2} carbonation of standard portland cements

    Energy Technology Data Exchange (ETDEWEB)

    Rubin, J.B.; Carey, J.; Taylor, C.M.V.

    1997-08-01

    We are conducting experiments on an innovative transformation concept, using a traditional immobilization technique, that may significantly reduce the volume of hazardous or radioactive waste requiring transport and long-term storage. The standard practice for the stabilization of radioactive salts and residues is to mix them with cements, which may include additives to enhance immobilization. Many of these wastes do not qualify for underground disposition, however, because they do not meet disposal requirements for free liquids, decay heat, head-space gas analysis, and/or leachability. The treatment method alters the bulk properties of a cemented waste form by greatly accelerating the natural cement-aging reactions, producing a chemically stable form having reduced free liquids, as well as reduced porosity, permeability and pH. These structural and chemical changes should allow for greater actinide loading, as well as the reduced mobility of the anions, cations, and radionuclides in aboveground and underground repositories. Simultaneously, the treatment process removes a majority of the hydrogenous material from the cement. The treatment method allows for on-line process monitoring of leachates and can be transported into the field. We will describe the general features of supercritical fluids, as well as the application of these fluids to the treatment of solid and semi-solid waste forms. some of the issues concerning the economic feasibility of industrial scale-up will be addressed, with particular attention to the engineering requirements for the establishment of on-site processing facilities. Finally, the initial results of physical property measurements made on portland cements before and after supercritical fluid processing will be presented.

  5. Enhancement of cemented waste forms by supercritical CO2 carbonation of standard portland cements

    International Nuclear Information System (INIS)

    We are conducting experiments on an innovative transformation concept, using a traditional immobilization technique, that may significantly reduce the volume of hazardous or radioactive waste requiring transport and long-term storage. The standard practice for the stabilization of radioactive salts and residues is to mix them with cements, which may include additives to enhance immobilization. Many of these wastes do not qualify for underground disposition, however, because they do not meet disposal requirements for free liquids, decay heat, head-space gas analysis, and/or leachability. The treatment method alters the bulk properties of a cemented waste form by greatly accelerating the natural cement-aging reactions, producing a chemically stable form having reduced free liquids, as well as reduced porosity, permeability and pH. These structural and chemical changes should allow for greater actinide loading, as well as the reduced mobility of the anions, cations, and radionuclides in aboveground and underground repositories. Simultaneously, the treatment process removes a majority of the hydrogenous material from the cement. The treatment method allows for on-line process monitoring of leachates and can be transported into the field. We will describe the general features of supercritical fluids, as well as the application of these fluids to the treatment of solid and semi-solid waste forms. some of the issues concerning the economic feasibility of industrial scale-up will be addressed, with particular attention to the engineering requirements for the establishment of on-site processing facilities. Finally, the initial results of physical property measurements made on portland cements before and after supercritical fluid processing will be presented

  6. Effect of sulfur on the polymorphism and reactivity of dicalcium silicate of Portland clinker Efeito do enxofre no polimorfismo e reatividade do silicato dicálcico do clínquer Portland

    OpenAIRE

    F. R. D. Andrade; S. D Gomes; M Pecchio; Y Kihara; F. M. S Carvalho; J. R Matos

    2011-01-01

    The present study regards the effect of sulfur in dicalcium silicate (Ca2SiO4), a major crystalline phase (20 to 40 wt.%) of the ordinary Portland cement clinker. Dicalcium silicate is also known as C2S (2CaO.SiO2) or belite. The synthesis of the C2S samples was made with high purity reactants with addition of sulfur as CaSO4.2H2O, mixed according to the stoichiometric proportion 2Ca:(1-x)Si:xS, in which x corresponds to the cationic proportion of sulfur, with values ranging from 0 to 20%. Ad...

  7. Basalt mine-tailings as raw-materials for Portland clinker Rejeitos da mineração de basalto como matérias-primas para clínquer Portland

    OpenAIRE

    F. R. D. Andrade; M Pecchio; D. P Bendoraitis; T. J Montanheiro; Y Kihara

    2010-01-01

    Large volumes of waste materials are produced by crushing of basaltic rocks for aggregate production, which is widely used in regions that lack rocks of granitic or gneissic composition. Two types of waste materials are produced (a) quarry fines, which are in part used as fine aggregates in concrete and (b) vesicular basalt, a porous variety of basalt that is useless as aggregate. This paper presents a procedure to use basaltic mine-tailings as raw-mixtures for Portland cement by adjusting th...

  8. Evaluation of Antioxidant and Antiproliferative Properties of Three <em>Actinidia> (<em>Actinidia> <em>kolomikta>, <em>Actinidia argutaem>, <em>Actinidia> <em>chinensis> Extracts <em>in Vitroem>

    Directory of Open Access Journals (Sweden)

    Jia-Ren Liu

    2012-05-01

    Full Text Available The total phenolic content, total flavonoid content, vitamin C content, and antioxidant activities of ethanol extracts from different kiwifruit varieties (<em>Actinidia> <em>kolomikta>, <em>Actinidia argutaem>, <em>Actinidia> <em>chinensis> were determined in this study. Multiple scavenging activity assays including the hydroxyl radical, O2·radical, DPPH, and the ABTS+ radical scavenging activity assays were used to identify the antioxidant activities of <em>Actinidia> extracts. The cell viability of HepG2 and HT-29 cells was also examined in this study. The results demonstrated that the <em>Actinidia kolomiktaem> extract had a higher antioxidant activity than the other two <em>Actinidia> extracts. There is a positive correlation between antioxidant activity and the polyphenols and vitamin C content in all three extracts (<em>R>2 ≥ 0.712, <em>p> em>< 0.05. The <em>Actinidia argutaem> extract had the highest inhibitory effect on HepG2 and HT-29 cell growth. These results provide new insight into the health functions of fruit and demonstrate that <em>Actinidia> extracts can potentially have health benefits.

  9. Good Grief Kids: An Exploratory Analysis of Grieving Children and Teens at The Dougy Center in Portland, Oregon

    OpenAIRE

    Sorensen, Karen

    2002-01-01

    Every year in the United States, anywhere from 200,000 to 400,000 youths under the age of 19 will experience the death of a parent (or both) or a sibling. The Dougy Center in Portland, Oregon, was established in 1983 to assist grieving children. Support groups are based on principles of nondirective play therapy. During the years 1996-2000, The Dougy Center administered questionnaires to a number of its clients. The results of one of these questionnaires, The Center for Epidemiological Studie...

  10. What is the Role of Universities in High-tech Economic Development? The Case of Portland, Oregon, and Washington, DC

    OpenAIRE

    Heike Mayer

    2006-01-01

    This paper focuses on two regions in the United States that have emerged as high-technology regions in the absence of major research universities. The case of Portland's Silicon Forest is compared to Washington, DC. In both regions, high-technology economies grew because of industrial restructuring processes. The paper argues that in both regions other actors—such as firms and government laboratories—spurred the development of knowledge-based economies and catalysed the engagement of high...

  11. 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-compo......-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....

  12. 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.

  13. Corrosion rate of steel embedded in blended Portland and fluid catalytic cracking catalyst residue (FC3R) cement mortars

    OpenAIRE

    Payá, J.; Garcés, P.; Zornoza, E.

    2008-01-01

    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 ste...

  14. Healing of apical rarefaction of three nonvital open apex anterior teeth using a white portland cement apical plug

    OpenAIRE

    Amitabha Chakraborty; Bibhas Dey; Reema Dhar; Prabir Sardar

    2012-01-01

    The major challenge of performing root canal treatment in an open apex pulp-less tooth is to obtain a good apical seal. MTA has been successfully used to achieve a good apical seal, wherein the root canal obturation can be done immediately. MTA and White Portland Cement has been shown similarity in their physical, chemical and biological properties and has also shown similar outcome when used in animal studies and human trials. In our study, open apex of three non vital upper central incisors...

  15. 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

    Solid-state, magic-angle spinning (MAS) NMR spectroscopy represents a valuable tool for structural investigations on the nanoscale of the most important phases in anhydrous and hydrated Portland cements and of various admixtures. This is primarily due to the fact that the method reflects the first...... have been investigated in detail by 29Si and 27Al MAS NMR where the combination of the results for these spin-nuclei provides important information on the degree of Al-incorporation in the C-S-H structure and of the average chain lengths of tetrahedral SiO4 and AlO4 units. This presentation will...

  16. Detailed characterization of current North American portland cements and clinkers and the implications for the durability of modern concrete

    Science.gov (United States)

    Arjunan, P.

    The current study has been undertaken with a view to rationalize the relation between the cement characteristics and concrete properties with the fresh set of data collected from the North American portland cements. The important chemical and physical characteristics of the cement discussed are (a) chemical analysis, (b) phase calculations, (c) various particle characterizations and (d) rheological properties. The important concrete properties discussed are (a) alkali silica reactivity, (b) sulfate attack, (c) delayed ettringite formation (d) chloride ion permeability and (e) compressive strength. Relationship between the cement characteristics and concrete durability was determined using regression methods. The heat of hydration was mainly influenced by the variation in C 3A, SO3, equivalent Na2O contents, and fineness of portland cements. When there was no variation in C3A, SO 3, and fineness, the hydration kinetics of the cement was mainly controlled by the silicate phase hydration. The 7-day hydration was negatively correlated to C2S or C4AF content. As the C2S or C 4AF content increased, the 7-day heat of hydration decreased. C 3S content showed a positive correlation to 1 and 7-day heats of hydration, but significant negative correlation to 14 and 28-day hydration. Equivalent alkalis showed a strong positive correlation to ASR at 2 weeks. SO3 content of portland cement also showed a positive correlation to ASR expansion. A strong negative correlation was observed between C4AF content of portland cement and sulfate attack expansion at 4 and 6 months of exposure. The correlation to sulfate attack was stronger when the ratios of C3A/C4AF were taken into account. C3A content exhibited a negative correlation to chloride ion permeability. This correlation decreased as the curing period increased. SO 3 content also exhibited a negative correlation to the chloride ion permeability. Only alkalis showed a strong negative correlation to the compressive strength after 3

  17. 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)

  18. Study concerning the use of cement and/or charcoal as grounding resistance reducers in rods and counterweights; Estudo sobre utilizacao de cimento e/ou carvao vegetal (moinha) como redutores de resistencia de aterramento em hastes e contrapesos

    Energy Technology Data Exchange (ETDEWEB)

    Viegas, Cesar S. [Companhia Energetica de Minas Gerais (CEMIG), Belo Horizonte, MG (Brazil)

    1991-12-31

    This work presents an alternative to the minimization of the problems related to the resistivity value of grounding in radio communication stations placed in high resistivity soils. The work is based in the analysis of the behaviour of several materials used in the treatment of the soil aiming a satisfactory reduction of the grounding resistivity value added to a low cost. Among such materials the charcoal points as the one which presents better performance, even by the resistivity point of view as the economic cost point of view 5 refs., 7 figs., 4 tabs.

  19. 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

    OpenAIRE

    Sandra Oda; Jose Leomar Fernandes Junior

    2001-01-01

    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 la...

  20. 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)

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

    OpenAIRE

    Carlos Alberto Nobrega; Paulo Edison Martins da Silveira

    2005-01-01

    The generation of Construction and Demolition Wastes (CDW) is a hugeenvironmental problem. In Piracicaba-SP, approximately 620 tons of these wastes are generated every day. This problem results in several environmental damages such as: irregular placing of wastes accumulating trash that attract animals capable to transmit illness; rubble on public roads and on streams that affect draining and stability on hills; degradation of urban visual; reduction of shelf-life of the levellings and nonren...

  2. <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.

  3. 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

    OpenAIRE

    Gaspar-Tébar, Demetrio; Sagrera-Moreno, José Luis

    1987-01-01

    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...

  4. 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

  5. Electromagnetic interference shielding with Portland cement paste containing carbon materials and processed fly ash

    Directory of Open Access Journals (Sweden)

    Zornoza, E.

    2010-12-01

    Full Text Available The study described in this article explored the effect of adding different types of carbon materials (graphite powder and three types of carbon fibre, fly ash (with 5.6%, 15.9% and 24.3% Fe2O3, and a mix of both on electromagnetic interference (EMI shielding in Portland cement pastes. The parameters studied included the type and aspect ratio of the carbonic material, composite material thickness, the frequency of the incident electromagnetic radiation and the percentage of the magnetic fraction in the fly ash. The findings showed that the polyacrylonitrile-based carbon fibres, which had the highest aspect ratio, provided more effective shielding than any of the other carbon materials studied. Shielding was more effective in thicker specimens and at higher radiation frequencies. Raising the magnetic fraction of the fly ash, in turn, also enhanced paste shielding performance. Finally, adding both carbon fibre and fly ash to the paste resulted in the most effective EMI shielding as a result of the synergies generated.

    En el presente trabajo se investiga la influencia de la adición de diferentes tipos de materiales carbonosos (polvo de grafito y 3 tipos de fibra de carbono, de una ceniza volante con diferentes contenidos de fase magnética (5,6%, 15,9% y 24,3% de Fe2O3 y de una mezcla de ambos, sobre la capacidad de apantallar interferencias electromagnéticas de pastas de cemento Pórtland. Entre los parámetros estudiados se encuentra: el tipo de material carbonoso, la relación de aspecto del material carbonoso, el espesor del material compuesto, la frecuencia de la radiación electromagnética incidente y el porcentaje de fracción magnética en la ceniza volante. Los resultados obtenidos indican que entre los materiales carbonosos estudiados son las fibras de carbono basadas en poliacrilonitrilo con una mayor relación de aspecto las que dan mejores resultados de apantallamiento. Al aumentar

  6. 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.

  7. A study of naturally occurring, radionuclide bearing deposits at Portland Creek, Newfoundland

    International Nuclear Information System (INIS)

    A small uraniferous peat deposit located near Portland Creek, Newfoundland was investigated as part of the National Uranium Tailings Program (NUTP). The purpose of the investigation was to provide data on naturally occurring uranium series radionuclides at a surface location that could be used to compare with the predictions of mathematical models. The investigation was carried out between August 18 and 30, 1984 by CBCL Limited with the assistance of Golder Associates, SENES Consultants Limited, Environmental Design Group and Monenco Analytical Laboratories. The investigation involved the determination of the geological and hydrogeological conditions of the deposit site and collection of soil, water and biological samples. The samples were analyzed for major element chemistry, uranium and its various decay series radionuclides including radium-226 and the ratio of uranium-234 to uranium-238. The uranium mineralization was found to be associated with a peat deposit that has accumulated in post-glacial time. The deposit is situated within a groundwater discharge zone at the toe of a granitic talus pile that extends downward from the Long Range Mountains. The concentration of uranium within the peat deposit was found to vary from 100 to 28000 ppm, however, the activities of the uranium decay series radionuclides were comparatively very low. Radium-226 activities were found to vary from 0.5 Bq/g to 15.0 Bq/g. Little influence from the deposit was noted in the surrounding water bodies, fish samples and vegetation. Based on the results of the study the uranium mineralization within the peat is considered to be the result of precipitation or adsorption from groundwater that had previously leached uranium from the granitic talus which forms the groundwater recharge zone. The major geochemical mechanism for deposition is considered to be associated with the strong reducing conditions encountered within the peat. Being a recent deposit (i.e. less than 10,000-15,000 years old

  8. 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.

  9. 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.

  10. Influence on the physical-mechanical properties of portland-cement mortar, have admixtures of colophony and tannin

    Directory of Open Access Journals (Sweden)

    Fernández Cánovas, M.

    1989-12-01

    Full Text Available The colophony has been used as an admixture in the Portland cement mortar with the intention to observe its influence on the air content, water absorption, adhesive capacity and mechanical properties. The results obtained have shown that, the colophony acts as air entrainment, reduces the permeability and improves the adhesion between the past and aggregates. Likewise, the addition of tannin and montan wax to the colophony has the efect of reducing the formation of foam and improves the impermeability of the mortar.

    Se ha empleado la colofonia como aditivo en el mortero de cemento portland con el fin de observar su influencia sobre el contenido de aire, absorción de agua, capacidad adhesiva y propiedades mecánicas. Los resultados obtenidos han puesto de manifiesto que la colofonia actúa como aireante, aumenta la impermeabilidad y mejora la adherencia de la pasta al árido. Asimismo, la adición de tanino y cera montana a la colofonia tiene el efecto de reducir la formación de espuma y mejorar también la impermeabilidad del mortero.

  11. Evaluation of physical stability and leachability of Portland Pozzolona Cement (PPC) solidified chemical sludge generated from textile wastewater treatment plants

    International Nuclear Information System (INIS)

    Highlights: ► Stabilization/solidification of chemical sludge from textile wastewater treatment plants using Portland Pozzolona Cement (PPC) containing fly ash. ► Physical engineering (compressive strength and block density) indicates that sludge has potential to be reused for construction purpose after stabilization/solidification. ► Leaching of heavy metals from stabilized/solidified materials were within stipulated limits. ► There is a modification of microstructural properties of PPC with sludge addition as indicated by XRD and SEM patterns. - Abstract: 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.

  12. Microstructure: Surface and cross-sectional studies of hydroxyapatite formation on the surface of white Portland cement paste in vitro

    International Nuclear Information System (INIS)

    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. Crystal chemistry of portland cement hydrates as radioactive waste hosts. Final report, June 15, 1983-June 14, 1984

    International Nuclear Information System (INIS)

    Portland cement hydrates have been used as encapsulant/host phases in radioactive waste management. However, their phase chemistry and stability relationships are poorly defined. Therefore, on occasion, they have not performed as well as expected. As a result, their use has been mainly limited to low-level waste disposal. Since this knowledge gap existed, we had begun to investigate the crystal chemistry of the portland cement hydrates. It was our objective to identify potential hydrate host phases which were not only suitable for isolating radioactive-waste species but also inexpensive, easily processed, low-temperature materials. Initially, we were concentrating upon two areas of interest: the fixation of iodine by the calcium aluminate hydrates and the feasibility of using Stratling's compound as a host phase for cesium and strontium fixation. In both cases, a phase equilibrium study was initiated in order to identify phase relations and consequences of adding the species of interest to the system. An iodine-containing analogue of calcium monosulfoaluminate hydrate (C3A.CaI2.xH2O) was identified as a possible host phase. CsOH was added to formulations in the neighborhood of Stratling's compound, in order to establish phase relations and identify the fixation ability of Stratling's compound and its associated hydrates. 11 figures, 9 tables

  14. Crystal chemistry of portland cement hydrates as radioactive waste hosts. Progress report, June 15, 1983-February 7, 1984

    International Nuclear Information System (INIS)

    Portland cement hydrates have been used as encapsulant/host phases in radioactive waste management. However, their phase chemistry and stability relationships are poorly defined. Therefore, on occassion, they have not performed as well as expected. As a result, their use has been mainly limited to low-level waste disposal. Since this knowledge gap exists, we have begun to investigate the crystal chemistry of the portland cement hydrates. It is our objective to identify potential hydrate host phases which are not only suitable for isolating radioactive-waste species but also inexpensive, easily processed, low-temperature materials. Initially, we have been concentrating upon two areas of interest: The fixation of iodine by the calcium aluminate hydrates and the feasibility of using Straling's compound as a host phase for cesium and strontium fixation. In both cases, a phase equilibrium study has been initiated in order to identify phase relations and consequences of adding the species of interest to the system. An iodine-containing analogue of calcium monosulfoaluminate hydrate (C3A.CaI2.xH2O) has been identified as a possible host phase. CsOH and Sr(OH)2 are being added to formulations in the neighborhood of Stratling's compound, in order to establish phase relations and identify the fixation ability of Stratling's compound and its associated hydrates. 10 figures, 6 tables

  15. 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

  16. 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

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. Geochemistry of Wellbore Integrity in CO2 Sequestration: Portland Cement-Steel-Brine-CO2 Interactions (Invited)

    Science.gov (United States)

    Carey, J. W.

    2013-12-01

    Effective geologic sequestration of CO2 requires long-term storage with very low leak rates. Numerous studies have identified wells as one of the key risk factors for CO2 leakage including purpose-built injection and monitoring wells in addition to older wells in and above the storage reservoir. All wells have the potential to leak due to faulty construction or other defects. However, geochemical reactions induced by CO2 could result in damage to Portland cement and steel that are used in the well to isolate reservoir fluids from underground drinking water sources and the surface. This concern is based on the thermodynamic incompatibility of CO2-saturated aqueous fluids with Portland cement and steel, which leads to relatively rapidly reactions that form, principally, calcium carbonate and iron carbonate. Despite this thermodynamic fate, wellbore materials perform and maintain zonal isolation in field and experimental observations. This is understood as a consequence of coupled behavior between flow of reactants (CO2-water) and the rate of dissolution and precipitation of cement or corrosion of steel. In the restricted flow environments found in wellbore systems, cements are carbonated but do not suffer significant deterioration of hydrologic or mechanical properties. In fact, cement carbonation often results in reduced permeability and enhanced mechanical strength. While steel is susceptible to corrosion, wellbore environments allow development of protective iron carbonate scale. In addition, the presence of Portland cement, even carbonated cement, provides protection against significant rates of corrosion. The impact of geochemical reactions in the wellbore environment cannot be separated from coupled flow, thermal and mechanical processes. CO2-induced chemical reactions migrating upward from a storage reservoir will not result in the creation of defects or the wholesale dissolution of cement or steel. Defects must exist that allow CO2×brine to flow and to come

  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. 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

  5. Determination of appropriate mix ratios for concrete grades using Nigerian Portland-limestone grades 32.5 and 42.5

    Directory of Open Access Journals (Sweden)

    Kazeem Kayode ADEWOLE

    2015-05-01

    Full Text Available The construction of buildings by incompetent craftsmen and the use of low quality building materials, including low quality concrete have been identified in the literature as two of the major reasons for the incessant collapse of building in Nigeria. The roadside craftsmen/artisans usually/generally construct buildings using 1:2:4 cement-fine aggregate-large aggregate mix ratio irrespective of the cement strength class. In this paper, the investigation conducted to determine the appropriate concrete mix ratios required to produce Class 20/25 and Class 25/30 concretes commonly used for design of building structural members using the Portland-limestone cement grades 32.5 and 42.5 that are available in the Nigerian open market is presented. Investigation revealed that the cube compressive strength of 1:2:4 concrete produced with Portland-limestone cement grade 32.5 is less than the minimum 25MPa required for concrete Class 20/25 and a richer 1:1.5:3 concrete produced with Portland-limestone cement grade 32.5 may be needed to produce concrete Class 20/25. Investigation also revealed that Portland-limestone cement grade 32.5 may not be suitable for the production of concrete class 25/30 with cube compressive strength of 30MPa as the cube compressive strength of 1:1:2 concrete produced with Portland-limestone cement grade 32.5 may not attain 30MPa. Concrete strength classes 20/25 and class 25/30 can be produced with Portland-limestone cement grade 42.5 using 1:2:4 and 1:1.5:3 mix ratios respectively. To produce concrete with strength class C20/25 which is the minimum concrete strength class recommended for the construction of the load-bearing building structural members using the 1:2:4 mix ratio, Portland-limestone cement grade 42.5 is required.

  6. 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

  7. 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.

  8. 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.

  9. Characterization using thermomechanical and differential thermal analysis of the sinterization of Portland clinker doped with CaF2

    International Nuclear Information System (INIS)

    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 CaF2 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 (Ca3SiO5) is higher when a certain amount of CaF2 was present during the clinkerization process.

  10. Use of alumina spent catalyst and RFCC wastes from petroleum refinery to substitute bauxite in the preparation of Portland clinker.

    Science.gov (United States)

    Al-Dhamri, Hilal; Melghit, Khaled

    2010-07-15

    Bauxite was substituted with spent catalysts for clinker preparation. Three different clinkers were prepared: one with bauxite as a reference, one with spent alumina catalyst and another with reduced fluid cracking catalyst. Powder X-ray diffraction technique, thermal analysis and scanning electron microscope were used to characterize each clinker sample. Rietveld refinement shows that, in all clinkers prepared, alite was formed with hexagonal lattice and monoclinic belite has higher unit cell volume compared to the known beta-Ca(2)SiO(4). The physical and mechanical properties (specific area, setting time, heat of hydration, soundness and compressive strength) of the cement samples were studied. The results show that substitution of bauxite by spent catalysts gave close results in terms of chemical composition, physical and mechanical properties of the Portland clinker. Also it shows the spent catalysts do not affect the quality of the prepared cement. PMID:20395040

  11. Use of alumina spent catalyst and RFCC wastes from petroleum refinery to substitute bauxite in the preparation of Portland clinker

    International Nuclear Information System (INIS)

    Bauxite was substituted with spent catalysts for clinker preparation. Three different clinkers were prepared: one with bauxite as a reference, one with spent alumina catalyst and another with reduced fluid cracking catalyst. Powder X-ray diffraction technique, thermal analysis and scanning electron microscope were used to characterize each clinker sample. Rietveld refinement shows that, in all clinkers prepared, alite was formed with hexagonal lattice and monoclinic belite has higher unit cell volume compared to the known β-Ca2SiO4. The physical and mechanical properties (specific area, setting time, heat of hydration, soundness and compressive strength) of the cement samples were studied. The results show that substitution of bauxite by spent catalysts gave close results in terms of chemical composition, physical and mechanical properties of the Portland clinker. Also it shows the spent catalysts do not affect the quality of the prepared cement.

  12. Calculation of radiation attenuation coefficients in Portland cements mixed with silica fume, blast furnace slag and natural zeolite

    International Nuclear Information System (INIS)

    This paper presents the radiation attenuation coefficients expressed as mass attenuation coefficients for Portland cement, zeolite, blast furnace slag, silica fume and their mixed types in function of the Photon energy over the energy range of 1 keV to 2 MeV. It was observed that different percentages of constituents in cement and cement mixed with different additives such as zeolite, silica fume and blast furnace slag, lead to significant variations in total mass attenuation coefficients. The elemental compositions of samples were analyzed using a wavelength dispersive XRF spectrometer. The calculated values of total mass attenuation coefficients were discussed on the basis of different percentages of constituents of cement and cement mixed with different additives

  13. 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>

  14. Evaluation of Pseudopteroxazole and Pseudopterosin Derivatives against <em>Mycobacterium> <em>tuberculosis> and Other Pathogens

    Directory of Open Access Journals (Sweden)

    Malcolm W. B. McCulloch

    2012-08-01

    Full Text Available Pseudopterosins and pseudopteroxazole are intriguing marine natural products that possess notable antimicrobial activity with a commensurate lack of cytotoxicity. New semi-synthetic pseudopteroxazoles, pseudopteroquinoxalines and pseudopterosin congeners along with simple synthetic mimics of the terpene skeleton were synthesized. In order to build structure-activity relationships, a set of 29 new and previously reported compounds was assessed for <em>in> <em>vitro> antimicrobial and cytotoxic activities. A number of congeners exhibited antimicrobial activity against a range of Gram-positive bacteria including <em>Mycobacterium> <em>tuberculosis> H37Rv, with four displaying notable antitubercular activity against both replicating and non-replicating persistent forms of <em>M.> <em>tuberculosis>. One new semi-synthetic compound, 21-((1<em>H>-imidazol-5-ylmethyl-pseudopteroxazole (7a, was more potent than the natural products pseudopterosin and pseudopteroxazole and exhibited equipotent activity against both replicating and non-replicating persistent forms of <em>M.> <em>tuberculosis> with a near absence of <em>in> <em>vitro> cytotoxicity. Pseudopteroxazole also exhibited activity against strains of <em>M.> <em>tuberculosis> H37Rv resistant to six clinically used antibiotics.

  15. Stabilization/solidification (S/S) of mercury-contaminated hazardous wastes using thiol-functionalized zeolite and Portland cement.

    Science.gov (United States)

    Zhang, Xin-Yan; Wang, Qi-Chao; Zhang, Shao-Qing; Sun, Xiao-Jing; Zhang, Zhong-Sheng

    2009-09-15

    Stabilization/solidification (S/S) of mercury-containing solid wastes using thiol-functionalized zeolite and cement was investigated in this study. The thiol-functionalized zeolite (TFZ) used in the study was obtained by grafting the thiol group (-SH) to the natural clinoptilolite zeolites, and the mercury adsorption by TFZ was investigated. TFZ was used to stabilize mercury in solid wastes, and then the stabilized wastes were subjected to cement solidification to test the effectiveness of the whole S/S process. The results show that TFZ has a high level of -SH content (0.562 mmol g(-1)) and the adsorption of mercury by TFZ conform to the Freundlich adsorption isotherm. The mercury adsorption capacity is greatly enhanced upon thiol grafting, the maximum of which is increased from 0.041 mmol Hg g(-1) to 0.445 mmol Hg g(-1). TFZ is found to be effective in stabilizing Hg in the waste surrogate. In the stabilization process, the optimum pH for the stabilization reaction is about 5.0. The optimum TFZ dosage is about 5% and the optimum cement dosage is about 100%. Though Cl(-) and PO(4)(3-) have negative effects on mercury adsorption by TFZ, the Portland cement solidification of TFZ stabilized surrogates containing 1000 mg Hg/kg can successfully pass the TCLP leaching test. It can be concluded that the stabilization/solidification process using TFZ and Portland cement is an effective technology to treat and dispose mercury-containing wastes. PMID:19376646

  16. AVALIAÇÃO IN VITRO DA LIBERAÇÃO DE FLÚOR DE CIMENTOS DE IONÔMERO DE VIDRO E OUTROS MATERIAIS QUE CONTÊM FLÚOR IN VITRO FLUORIDE RELEASE FROM GLASS-IONOMERCEMENTS AND OTHER MATERIALS

    OpenAIRE

    TERADA, Raquel Sano Suga; Navarro, Maria Fidela de Lima; Carvalho, Ricardo Marins; TAGA Eulázio; 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...

  17. 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

    Santos, Rogério Lacerda dos

    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...

  18. Resistência mecânica a quente de concretos refratários aluminosos zero-cimento auto-escoantes contendo adições de microssílica e microssílica coloidal High temperature mechanical strength of self-flow zero-cement high-alumina castables containing microsilica and microsilica with coloidal silica additions

    OpenAIRE

    M. V. Gerotto; R. G. Pileggi; V. C. Pandolfelli

    2000-01-01

    Concretos refratários aluminosos contendo microssílica apresentam um grande potencial de aplicação tecnológica pela possibilidade de formação da fase mulita através da reação entre Al2O3 e SiO2. Porém, segundo o diagrama Al2O3 - SiO2 - CaO, seu uso é limitado a temperaturas próximas a 1300 ºC uma vez que a presença do CaO, contido no cimento de aluminato de cálcio, leva a formação de fases líquidas que prejudicam fortemente a sua resistência mecânica a altas temperaturas. Recentemente foi mos...

  19. 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.

  20. Reference Gene Selection in the Desert Plant <em>Eremosparton songoricuem>m>

    OpenAIRE

    Dao-Yuan Zhang; Yuan-Ming Zhang; Wood, Andrew J.; Xiao-Shuang Li; Hong-Lan Yang

    2012-01-01

    <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...

  1. 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

  2. In vitro evaluation of apical microleakage using different root-end filling materials Avaliação in vitro da microinfiltração marginal usando diferentes materiais retrobturadores

    Directory of Open Access Journals (Sweden)

    Márcia Carneiro Valera

    2006-01-01

    de guta-percha e cimento SealapexTM e, em seguida, foi realizado o seccionamento de 3mm do ápice radicular em ângulo de 90º em relação ao longo eixo do dente. Foram preparadas cavidades retroapicais com ponta diamantada em ultrasom, a uma profundidade de 3mm, e as raízes foram divididas aleatoriamente em 3 grupos de acordo com o material retrobturador: G1- Portland, G2 - MTA, G3 - Sealapex acrescido de óxido de zinco. As raízes foram impermeabilizadas externamente e imersas em fluido tissular simulado por 30 dias. Em cada grupo, 2 dentes serviram como controle positivo (não impermeabilização e negativo (total impermeabilização. Os espécimes foram imersos em corante Rhodamina B 0,2% por 24 horas para avaliação da infiltração marginal. Os cimentos Portland, SealapexTM + óxido de zinco e MTA apresentaram média de infiltração de 0,75; 0,35 e 0,35mm respectivamente, não havendo diferenças estatísticas significantes entre eles (p>0,05.

  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. 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

  5. Aoife Nolan, Rory O’Connell, Colin Harvey (eds., Human Rights and Public Finance: Budgets and the Promotion of Economic and Social Rights (Oxford and Portland: Hart Publishing, 2013

    Directory of Open Access Journals (Sweden)

    Floriana Ferro

    2014-03-01

    Full Text Available A review of: Aoife Nolan, Rory O’Connell, Colin Harvey (eds., Human Rights and Public Finance: Budgets and the Promotion of Economic and Social Rights (Oxford and Portland: Hart Publishing, 2013

  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. Quantitative study on the effect of high-temperature curing at an early age on strength development of concrete. Experiment with mortar using moderate-heat portland cement

    International Nuclear Information System (INIS)

    The effect of high-temperature curing at an early age on the strength development of concrete using moderate-heat portland cement was quantitatively studied. High-temperature curing conditions were set so as to give systematic variations in the temperature-time factors. As a result, the integrated value of curing temperature during the period having a significant effect on the strength development was proposed as a parameter that expressed the degree of high-temperature curing. The effect of high-temperature curing on the strength development of concrete using moderate-heat portland cement could be exactly predicted with the integrated value of curing temperature during the period from 0 to 3 days. (author)

  8. Acción del CO2 sobre un cemento portland. I. Influencia sobre los características químicas y fisicomecánicas

    Directory of Open Access Journals (Sweden)

    Historico, Demetrio Gaspar-Tebar

    1977-03-01

    Full Text Available El efecto que el dióxido de carbono produce sobre los compuestos anhidros e hidratados del cemento portland ha sido objeto de estudio por numerosos investigadores, debido a la influencia que ejerce en las propiedades de los conglomerados correspondientes. La reacción de carbonatación del cemento portland lleva consigo una modificación de la composición química y estructural del mismo que afecta a sus propiedades físicas y fisicomecánicas; hecho que puede influir, además, en grado distinto, en la durabilidad de las estructuras de hormigón.

  9. 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.

  10. 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

  11. Effect of Combined Calcium Hydroxide and Accelerated Portland Cement on Bone Formation and Soft Tissue Healing in Dog Bone Lesions

    Directory of Open Access Journals (Sweden)

    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

  12. Assessing the Impacts of Smart Growth Policies on Home Developers in a Bi-state Metropolitan Area: Evidence from the Portland Metropolitan Area

    OpenAIRE

    Hongwei Dong; John Gliebe

    2012-01-01

    While there are many empirical studies examining the effectiveness of smart growth policies, few of them study the perspective of developers, the major urban space producers in US cities. This article assesses the impacts of smart growth policies on home developers in the Portland bi-state metropolitan area by developing home developer location choice models. The study shows that home developers in the region are sensitive to most smart growth policies being implemented in the region, but the...

  13. KAJIAN EKSPERIMENTAL PADA MIKROSTRUKTUR DAN KEKUATAN BETON YANG MENGGUNAKAN AIR LAUT, PASIR LAUT DAN SEMEN PORTLAND KOMPOSIT SEBAGAI INOVASI TEKNOLOGI UNTUK MENDUKUNG PEMBANGUNAN INFRASTRUKTUR PULAU- PULAU TERPENCIL

    OpenAIRE

    Wihardi Tjaronge; Rita Irmawaty; Sakti Adji Adisasmita

    2014-01-01

    Kajian Eksperimental pada Mikrostruktur dan Kekuatan Beton yang Menggunakan Air Laut, Pasir Laut dan Semen Portland Komposit sebagai Inovasi Teknologi untuk Mendukung Pembangunan Pulau-Pulau Terpencil RINGKASAN Kendala utama pengembangan budidaya perairan (aqua culture) dan pembangunan infrastruktur di gugusan pulau-pulau terpencil serta daerah pesisir pantai yang lebih rendah dari permukaan air laut (low land) adalah sumber air bersih yang tidak memadai untuk memproduksi beton. P...

  14. Impact of a 70°C temperature on an ordinary Portland cement paste/claystone interface: An in situ experiment

    OpenAIRE

    Lalan, Philippines; Dauzères, Alexandre; De Windt, Laurent; Bartier, Danièle; Sammaljärvi, Juuso; BARNICHON, Jean-Dominique; Techer, Isabelle; Detilleux, Valéry

    2016-01-01

    Radioactive wastes in future underground disposal sites will induce a temperature increase at the interface between the cementitious materials and the host rock. To understand the evolution of Portland cement in this environment, an in situ specific device was developed in the Underground Research Laboratory in Tournemire (France). OPC cement paste was put into contact with clayey rock under water-saturated conditions at 70°C. The initial temperature increase led to ettringite dissolution and...

  15. Perfil de permeabilidade em concretos refratários Permeability gradient in refractory castables

    Directory of Open Access Journals (Sweden)

    M. D. M. Innocentini

    2001-03-01

    Full Text Available A durabilidade de um concreto refratário está diretamente associada à facilidade com que gases e líquidos corrosivos penetram em sua estrutura porosa. Muitas vezes, contudo, a resistência ao escoamento não é uniforme no interior do material, podendo levar a resultados não representativos do corpo como um todo, dependendo da região de análise. Neste trabalho, o perfil de permeabilidade em função da profundidade foi investigado para concretos refratários auto-escoantes com ultrabaixo teor de cimento obtidos em diferentes temperaturas de tratamento térmico. Os resultados permitiram concluir que a eliminação de água de hidratação, a sinterização e o destacamento da matriz-agregado são os mecanismos principais responsáveis pela variação da permeabilidade entre 110 ºC e 1650 °C. A leve sedimentação dos agregados para o interior da amostra durante a moldagem e o empacotamento diferenciado da matriz na superfície exposta à atmosfera explicam o gradiente de permeabilidade observado nos concretos.The durability of refractory castables is ultimately related with the ability of fluids to penetrate and interact with the porous structure. In some cases, however, the flow resistance is not uniform within the refractory body, and a global analysis may result in misleading information about the refractory properties depending on the size and position of the sample. In this work, the permeability gradient was measured along the thickness of a self-flow ultra-low cement refractory castable as a function of the thermal treatment temperature. Results led to the conclusion that dehydration, sintering and microcracking are the key mechanisms for the variation in the permeability. The minor sedimentation of aggregates during casting and the better matrix packing on the sample surface explain the lower permeability at the surface exposed to atmosphere during the castable molding.

  16. International EMS Systems

    DEFF Research Database (Denmark)

    Langhelle, Audun; Lossius, Hans Morten; Silfvast, Tom;

    2004-01-01

    . Access to on-line medical advice of a physician is not available; (2) Finland: the autonomy of the individual municipalities and their responsibility to cover for primary and specialised health care, as well as the EMS, and the lack of supporting or demanding legislation regarding the EMS; (3) Iceland is...... the only country that has emergency medicine (EM) as a recognised speciality but there is a need for more fully trained specialists in EM; (4) Norway: the ordinary ground ambulance is pointed out as the weakest link in the EM chain and a health reform demands extensive co-operation between the new...... health enterprises to re-establish a nation-wide air ambulance service; (5) Sweden: to create evidence based medicine standards for treatment in emergency medicine, a better integration of all part of the chain of survival, a formalised education in EM and a nation wide physician staffed helicopter EMS...

  17. Concentration of electrolyte reserves of the juvenile african catfish clarias gariepinus (burchell, 1822) exposed to sublethal concentrations of portland cement powder in solution

    International Nuclear Information System (INIS)

    The study investigated the effect of sublethal concentrations (39.10, 19.55, 9.87 and 0.00 mg/l) of Portland cement powder in solution on the electrolyte reserves (sodium, potassium, calcium, chloride and inorganic phosphorus) in the serum, liver and kidney of the juvenile African catfish Clarias gariepinus after a 15 day exposure period. The basic function of the determined electrolyte reserves in the body lies in controlling fluid distribution, intra and extra cellular acidobasic equilibrium, maintaining osmotic pressure of body fluid and normal neuro-muscular irritability. The result revealed significant (P0.05) changes in inorganic phosphorus. Sodium, calcium, chloride and inorganic phosphorus and potassium were significantly (P0.05) different in liver and kidney, respectively. Ipso-facto, the effector organs viz: liver and kidney of teleost species - Clarias gariepinus which are primarily responsible for regulating water and ionic movement between external and internal milieu of fishes are susceptible to deleterious effects of Portland cement powder thus sublethal concentration (39.10 mg/l) of Portland cement powder in solution after a 15 day exposure has been most toxic and debilitating to the test fish. (author)

  18. Role of aluminous component of fly ash on the durability of Portland cement-fly ash pastes in marine environment

    International Nuclear Information System (INIS)

    The durability, of mixtures of two kinds of Spanish fly ashes from coal combustion (ASTM class F) with 0, 15 and 35% replacement of Portland cement by fly ash, in a simulated marine environment (Na2SO4+NaCl solution of equivalent concentration to that of sea water: 0.03 and 0.45 M for sulphate and chloride, respectively), has been studied for a period of 90 days. The resistance of the different mixtures to the attack was evaluated by means of the Koch-Steinegger test. The results showed that all the mixtures were resistant, in spite of the great amount of Al2O3 content of the fly ash. The diffusion of SO42-, Na+ and Cl- ions through the pore solution activated the pozzolanic reactivity of the fly ashes causing the corresponding microstructure changes, which were characterized by X-ray diffraction (XRD), mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). As a result, the flexural strength of the mixtures increased, principally for the fly ash of a lower particle size and 35% of addition

  19. 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.

  20. 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.

  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. 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.

  3. Calcium looping spent sorbent as a limestone replacement in the manufacture of portland and calcium sulfoaluminate cements.

    Science.gov (United States)

    Telesca, Antonio; Marroccoli, Milena; Tomasulo, Michele; Valenti, Gian Lorenzo; Dieter, Heiko; Montagnaro, Fabio

    2015-06-01

    The calcium looping (CaL) spent sorbent (i) can be a suitable limestone replacement in the production of both ordinary Portland cement (OPC) and calcium sulfoaluminate (CSA) cement, and (ii) promotes environmental benefits in terms of reduced CO2 emission, increased energy saving and larger utilization of industrial byproducts. A sample of CaL spent sorbent, purged from a 200 kWth pilot facility, was tested as a raw material for the synthesis of two series of OPC and CSA clinkers, obtained from mixes heated in a laboratory electric oven within temperature ranges 1350°-1500 °C and 1200°-1350 °C, respectively. As OPC clinker-generating mixtures, six clay-containing binary blends were investigated, three with limestone (reference mixes) and three with the CaL spent sorbent. All of them showed similar burnability indexes. Moreover, three CSA clinker-generating blends (termed RM, MA and MB) were explored. They included, in the order: (I) limestone, bauxite and gypsum (reference mix); (II) CaL spent sorbent, bauxite and gypsum; (III) CaL spent sorbent plus anodization mud and a mixture of fluidized bed combustion (FBC) fly and bottom ashes. The maximum conversion toward 4CaO·3Al2O3·SO3, the chief CSA clinker component, was the largest for MB and almost the same for RM and MA. PMID:25915150

  4. Influence of addition of calcium oxide on physicochemical properties of Portland cement with zirconium or niobium oxide

    Directory of Open Access Journals (Sweden)

    Mario Tanomaru-Filho

    2015-01-01

    Full Text Available Context: Calcium oxide (CaO may be added to mineral trioxide aggregate (MTA or Portland cement (PC to improve physicochemical and biological properties. Aims: To evaluate the physicochemical properties of PC associated with radiopacifiers and CaO. Materials and Methods: MTA Angelus, PC + 30% zirconium oxide (Zr, or 30% niobium oxide (Nb associated with 10 or 20% of CaO were evaluated. Gilmore needles were used to evaluate initial and final setting time. Compressive strength was evaluated after the periods of 24 hours and 21 days. pH was analyzed after 3, 12, 24 hours, 7, 14, 21 days. Solubility and flow tests were performed based on the ISO 6876. The data obtained were submitted to analysis of variance and Tukey tests (P ≤ 0.05. Results: The associations with 10% CaO showed greater strength that the associations with 20% CaO. The shortest initial setting time was observed for the association PC + Zr + 20% CaO and MTA. All the cements presented alkaline pH. The flow of all cements was similar. The highest solubility was found in the associations with 20% CaO. Conclusion: The addition of CaO to PC favored the alkaline property and the PC + Zr + 20% CaO presented setting time similar to MTA.

  5. The removal of phosphate ions from aqueous solution by fly ash, slag, ordinary Portland cement and related blends

    Energy Technology Data Exchange (ETDEWEB)

    N.M. Agyei; C.A. Strydom; J.H. Potgieter [University of Venda, Thohoyandou (South Africa). Department of Chemistry

    2002-12-01

    Phosphate ions have been removed from aqueous solution by fly ash, slag, ordinary Portland cement (OPC) and related cement blends. The rate and efficiency of PO{sub 4}{sup 3-} removal were found to increase in the order: fly ash, slag, OPC, apparently mimicking the order of increasing percent CaO in the adsorbents. Blending OPC with fly ash or slag evidently results in diminished PO{sub 4}{sup 3-} removal efficiency. Better removal was obtained at higher solute concentration, acidic pH and higher temperature. The effect of particle size and the speed of mixing were found not to be significant. A first-order kinetic model was used to obtain values for overall sorption rate constants and intraparticle diffusion constants. The Frumkin isotherm was found to be the appropriate equation for modelling isotherms from the experimental adsorption data, and values have been obtained for the isotherm constants. A 400-mg/l PO{sub 4}{sup 3-} (as P) solution was fed at a steady velocity of 2.0 cm/min through a 2.0-cm fixed-bed column (at pH 9.0 and 25{sup o}C), and breakthrough curves were constructed to obtain estimated adsorption capacity values of 32, 60, 75, 78 and 83 mg PO{sub 4}{sup 3-}/g adsorbent for fly ash, slag, OPC+fly ash, OPC+slag and OPC, respectively.

  6. International EMS Systems

    DEFF Research Database (Denmark)

    Langhelle, Audun; Lossius, Hans Morten; Silfvast, Tom;

    2004-01-01

    Emergency medicine service (EMS) systems in the five Nordic countries have more similarities than differences. One similarity is the involvement of anaesthesiologists as pre-hospital physicians and their strong participation for all critically ill and injured patients in-hospital. Discrepancies do....... Access to on-line medical advice of a physician is not available; (2) Finland: the autonomy of the individual municipalities and their responsibility to cover for primary and specialised health care, as well as the EMS, and the lack of supporting or demanding legislation regarding the EMS; (3) Iceland...... is the only country that has emergency medicine (EM) as a recognised speciality but there is a need for more fully trained specialists in EM; (4) Norway: the ordinary ground ambulance is pointed out as the weakest link in the EM chain and a health reform demands extensive co-operation between the new health...

  7. Isolation and Characterization of a Lycopene ε-Cyclase Gene of <em>Chlorella em>(Chromochloris> <em>zofingiensis>. Regulation of the Carotenogenic Pathway by Nitrogen and Light

    Directory of Open Access Journals (Sweden)

    Maria Angeles Vargas

    2012-09-01

    Full Text Available The isolation and characterization of the lycopene ε-cyclase gene from the green microalga <em>Chlorella em>(Chromochloris> <em>zofingiensis> (<em>Czlcy-e> was performed. This gene is involved in the formation of the carotenoids α-carotene and lutein. <em>Czlcy-e> gene encoded a polypeptide of 654 amino acids. A single copy of <em>Czlcy-e> was found in <em>C. zofingiensisem>. Functional analysis by heterologous complementation in <em>Escherichia coliem> showed the ability of this protein to convert lycopene to δ-carotene. In addition, the regulation of the carotenogenic pathway by light and nitrogen was also studied in <em>C. zofingiensisem>. High irradiance stress did not increase mRNA levels of neither lycopene β<em>->cyclase gene (<em>lcy-b> nor lycopene ε-cyclase gene<em> em>(lcy-e> as compared with low irradiance conditions, whereas the transcript levels of <em>psy>, <em>pds>, <em>chyB> and <em>bkt> genes were enhanced, nevertheless triggering the synthesis of the secondary carotenoids astaxanthin, canthaxanthin and zeaxanthin and decreasing the levels of the primary carotenoids α-carotene, lutein, violaxanthin and β-carotene. Nitrogen starvation <em>per seem> enhanced mRNA levels of all genes considered, except <em>lcy-e and pdsem>, but did not trigger the synthesis of astaxanthin, canthaxanthin nor zeaxanthin. The combined effect of both high light and nitrogen starvation stresses enhanced significantly the accumulation of these carotenoids as well as the transcript levels of <em>bkt> gene, as compared with the effect of only high irradiance stress.

  8. Emergency Medical Service (EMS) Stations

    Data.gov (United States)

    Kansas Data Access and Support Center — EMS Locations in Kansas The EMS stations dataset consists of any location where emergency medical services (EMS) personnel are stationed or based out of, or where...

  9. Evaluation of Photocatalytic Properties of Portland Cement Blended with Titanium Oxynitride (TiO2−xNy Nanoparticles

    Directory of Open Access Journals (Sweden)

    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.

  10. The <em>Opuntia streptacanthaem> <em>OpsHSP18 em>Gene Confers Salt and Osmotic Stress Tolerance in <em>Arabidopsis thalianaem>

    Directory of Open Access Journals (Sweden)

    Juan Francisco Jiménez-Bremont

    2012-08-01

    Full Text Available Abiotic stress limits seed germination, plant growth, flowering and fruit quality, causing economic decrease. Small Heat Shock Proteins (sHSPs are chaperons with roles in stress tolerance. Herein, we report the functional characterization of a cytosolic class CI sHSP (OpsHSP18 from <em>Opuntia streptacantha em>during seed germination in <em>Arabidopsis thalianaem> transgenic lines subjected to different stress and hormone treatments. The over-expression of the <em>OpsHSP18em> gene in <em>A. thalianaem> increased the seed germination rate under salt (NaCl and osmotic (glucose and mannitol stress, and in ABA treatments, compared with WT. On the other hand, the over-expression of the <em>OpsHSP18em> gene enhanced tolerance to salt (150 mM NaCl and osmotic (274 mM mannitol stress in <em>Arabidopsis> seedlings treated during 14 and 21 days, respectively. These plants showed increased survival rates (52.00 and 73.33%, respectively with respect to the WT (18.75 and 53.75%, respectively. Thus, our results show that <em>OpsHSP18em> gene might have an important role in abiotic stress tolerance, in particular in seed germination and survival rate of Arabidopsis plants under unfavorable conditions.

  11. 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

    Directory of Open Access Journals (Sweden)

    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.

  12. Características da sílica coloidal e seus efeitos em concretos refratários Characteristics of colloidal silica and its effects on refractory castables

    Directory of Open Access Journals (Sweden)

    M. V. M Magliano

    2010-06-01

    Full Text Available A sílica coloidal se apresenta como um promissor substituto do cimento de aluminato de cálcio para utilização em concretos mulitizáveis. O uso deste ligante promove adequada resistência mecânica a verde, facilidade de secagem, inibe a formação de fases de baixo ponto de fusão, além de favorecer a formação de mulita in-situ. Entretanto, as propriedades finais do concreto dependem das características da solução coloidal utilizada. O objetivo deste trabalho é comparar as propriedades a verde e a quente de sistemas mulitizáveis ligados por sílica coloidal, variando suas características, tais como teor de sólidos, área superficial e tipo de estabilizante. Os resultados indicaram que sílicas coloidais com alta área superficial reduzem a trabalhabilidade dos concretos e diminuem as propriedades a quente devido ao acentuado trincamento durante a cura. A refratariedade dos sistemas é ainda comparada com concretos ligados por cimento de aluminato de cálcio e alumina hidratável, ressaltando a superioridade do ligante coloidal.The colloidal silica has been shown as a promising substitute for the aluminate cement as a binder for refractory castables. It can promote suitable mechanical strength for green bodies, reduce the explosion risk and does not develop phases with low melting point in the alumina systems. In addition, they can induce the in-situ mullite formation. Nevertheless, the final properties of the castable can also depend on the colloidal suspension characteristics such as, solid concentration, surface area and stabilizing agents. This paper aims to compare the green and high temperature properties of castables using different types of colloidal silicas. The results showed that colloidal silica containing a high surface area builds up internal tensions and cracks during the drying process, which deteriorate the hot mechanical properties of the castables. Besides that, they also reduce the workability and the free flow

  13. 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...

  14. Evaluación de escorias de córdoba para su utilización en la industria del cemento Portland

    OpenAIRE

    Carvajal Vinasco, Juan Felipe

    2012-01-01

    Resumen: Las escorias junto con las puzolanas son materiales suplementarios del cemento Portland, lo cual significa que pueden sustituir o ser adicionadas al cemento. Su uso conduce a una disminución en las emisiones de gases de efectos de invernadero emitidos durante la descarbonatación en la etapa de clinkerización en el proceso productivo del cemento; disminuyen el consumo energético debido a que las adiciones sustituyen Clinker que se procesa a temperaturas de hasta 1500° C y los costos p...

  15. A comparative evaluation of compressive strength of Portland cement with zinc oxide eugenol and Polymer-reinforced cement: An in vitro analysis

    OpenAIRE

    S.Prakasam; Prakasam Bharadwaj; S C Loganathan; B Krishna Prasanth

    2014-01-01

    Objective: The purpose of this study is to evaluate the ultimate compressive strength of 50% and 25% Portland cement mixed with Polymer-reinforced zinc oxide eugenol and zinc oxide eugenol cement after 1 hour, 24 hours, and 7 days. Materials and Methods: One hundred and eighty samples were selected. The samples were made cylindrical of size 6 × 8 mm and were divided into six groups as follows with each group consisting of 10 samples. Group 1: Polymer-reinforced zinc oxide eugenol with...

  16. 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

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    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

  17. Kinetic and morphological differentiation of Ettringites in plain and blended Portland cements using Metakaolin and the ASTM C 452-68 test. Part I: kinetic differentiation

    OpenAIRE

    Talero, R.

    2008-01-01

    In this first part of the study, the results obtained in prior research with XRD and SEM, as well as the Le Chatelier-Ansttet test were confirmed with the ASTM C 452-68 test. To this end, 20%, 30% and 40% metakaolin (MK) was added to ten Portland cements, six OPCs and four SRPCs. Both the ten plain PCs and the 30 metakaolin (MK) blends were tested for two years under ASTM C 452-68 specifications, determining not only the percentage increase in length, ΔL(%), of the specimens, but also the sul...

  18. Expression of Selected <em>Ginkgo em>>biloba em>Heat Shock Protein Genes After Cold Treatment Could Be Induced by Other Abiotic Stress

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    Feng Xu

    2012-05-01

    Full Text Available Heat shock proteins (HSPs play various stress-protective roles in plants. In this study, three <em>HSP> genes were isolated from a suppression subtractive hybridization (SSH cDNA library of <em>Ginkgo bilobaem> leaves treated with cold stress. Based on the molecular weight, the three genes were designated <em>GbHSP16.8em>, <em>GbHSP17em> and <em>GbHSP70em>. The full length of the three genes were predicted to encode three polypeptide chains containing 149 amino acids (Aa, 152 Aa, and 657 Aa, and their corresponding molecular weights were predicted as follows: 16.67 kDa, 17.39 kDa, and 71.81 kDa respectively. The three genes exhibited distinctive expression patterns in different organs or development stages. <em>GbHSP16.8em> and <em>GbHSP70em> showed high expression levels in leaves and a low level in gynoecia, <em>GbHSP17em> showed a higher transcription in stamens and lower level in fruit. This result indicates that <em>GbHSP16.8em> and <em>GbHSP70 em>may play important roles in <em>Ginkgo> leaf development and photosynthesis, and <em>GbHSP17em> may play a positive role in pollen maturation. All three <em>GbHSPs> were up-regulated under cold stress, whereas extreme heat stress only caused up-regulation of <em>GbHSP70em>, UV-B treatment resulted in up-regulation of <em>GbHSP16.8em> and <em>GbHSP17em>, wounding treatment resulted in up-regulation of <em>GbHSP16.8em> and <em>GbHSP70em>, and abscisic acid (ABA treatment caused up-regulation of <em>GbHSP70em> primarily.

  19. Persistence of Vectobac WDG and Metoprag S-2G against Aedes aegypti larvae using a semi-field bioassay in Rio de Janeiro, Brazil Persistência de Vectobac WDG e Metoprag S-2g contra larvas de Aedes aegypti em ensaio simulado de campo no Rio de Janeiro, Brasil

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    José Bento Pereira Lima

    2005-02-01

    Full Text Available Persistence of Bacillus thuringiensis var. israelensis (Vectobac WDG and methoprene (Metoprag S-2G was evaluated against Aedes aegypti late third instar larvae of the Rockefeller strain in a semi-field bioassay. Tests were performed in Rio de Janeiro, using containers made of plastic, iron, concrete and asbestos, placed in a shaded area. The formulations used were 0.2 g of Vectobac-WDG and 1g of Metoprag S-2G per 100 liters of water in house storage containers. Vectobac WDG was tested twice, in March and in April/May, 2002. In March (temperature ranging from 21.5 to 39.3 ºC, 70-100% mortality was observed by the 7th day and declined abruptly thereafter. No significant differences were observed among the container types. In April/May (18.6 to 34.8 ºC mortality was higher than 70% to 30-36 days in all cases, except in the iron container (40% mortality on the 12th day. Metoprag S-2G was evaluated in April/May, 2002, and induced mortality higher than 70% up to 15 days in the plastic and iron containers and only seven days in the concrete container. In the asbestos container, maximal mortality was achieved on day one post-treatment (66%. Our results point to a low persistence of both formulations in the weather conditions of Rio de Janeiro.A persistência de Bacillus thuringiensis var. israelensis (Vectobac WDG e de Metoprene (Metoprag S-2G contra larvas de terceiro estadio de Aedes aegypti (linhagem Rockefeller foi avaliada em ensaios simulados de campo. Os testes foram realizados no Rio de Janeiro, em recipientes domésticos para estoque de água de plástico, ferro, cimento ou amianto, instalados em área sombreada. As formulações foram usadas nas concentrações de 0.2g / 100 l (Vectobac-WDG e 1g / 100 l (Metoprag S-2G. Vectobac WDG foi submetido a dois testes, em março e abril/maio, 2002. Em março (temperaturas entre 21.5 e 39.3 ºC, 70-100% de mortalidade foi observada no sétimo dia, declinando posteriormente. Não houve diferen

  20. Osteoartrites em equinos

    OpenAIRE

    Rocha, Francisco José Martins

    2008-01-01

    Dissertação de Mestrado Integrado em Medicina Veterinária A Osteoartrite (OA) é a principal causa de claudicação no cavalo de desporto e lazer, sendo uma afecção que tem grandes repercussões económicas. Este trabalho descreve algumas das características importantes da estrutura articular, bem como da sua fisiologia. Define a OA e todas as estruturas envolvidas no seu processo. Os mecanismos fisiopatológicos põem em evidência os factores de risco em causa e que determinam tod...