Determinación del calor de fraguado de cemento por icrocalorimetría

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Liliana Girlado G.

2010-07-01

Full Text Available Se determina el calor de fraguado del cemento Río Claro tipo III (Río Claro, Antioquia, Colombia por microcalorimetría de conducción de calor; así como también los efectos de la glucosa y de la sacarosa en el proceso de fraguado de este material. Al emplear 0,15 y 0,05% ( % en peso de estos aditivos en la preparación de las pastas, se observan retardos considerables en el fraguado de las mismas. Los aditivos también modifican el calor de fraguado: la pasta libre de estos presenta un valor de 38,03 J/g en tanto que la adición de glucosa y sacarosa producen valores menores, excepto en el caso de la sacarosa al 0,05% donde se observa un efecto térmico de 55.80 J/s,

MORTERO DE CEMENTO PÓRTLAND Y ARENA, MODIFICADO POR LA ADICIÓN DE PARTÍCULAS DE BAMBÚ / PORTLAND CEMENT MORTAR MODIFIED BY BAMBOO PARTICLES

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ANTONIO BERALDO

2009-04-01

Full Text Available RESUMENComo una consecuencia del desarrollo industrial, se generan cantidades significativas de residuos de las más variadas naturalezas. Además, se marcha para un rápido agotamiento de los recursos naturales, pues la mayoría de ellos no es obtenida de fuente renovable. Por su vez, el bambú presentase como una excelente alternativa para disminuir la explotación de las florestas nativas; todavia, diversos sectores tecnológicos brasileños aún no despertaron para las potencialidades de esa materia prima. Además también se destaca la posibilidad de utilización de particulas de bambú en el remplazo parcial o total de los agregados de origen mineral (arena y ripio. El objetivo de ese trabajo fue la evaluación de las características físicas y mecanicas de compuestos a base de mortero de cemento Portland y arena, modificado por la adición de partículas de bambú. El compuesto fue sometido a los ensayos de absorción del agua, de la velocidad del pulso ultrasónico (VPU y de las resistencias a la comprensión simple y diametral. Los resultados obtenidos indicaron el efecto del tratamiento aplicado a las particulas de bambú, del tipo de cemento empleado y del tipo de cemento empleado  del contenido de las particulas de bambú en las propiedades del compuesto. Palabras-llave: bambú, compuesto, VPU, END 

Caracterización de un cemento puzolánico

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Hugo Rincón

2010-03-01

Full Text Available Se caracterizáron las materias primas (caliza, yeso, y material pulozánico para la producción de cemento portland y el clinker obtenido en este proceso, por medio del análisis químico elemental y espectroscopia infrarroja. Se estudio el comportamiento al IR y a la comprensión de morteros elaborados a partir de cemento testigo y variaciones de material pulozánico (15, 35, 50 y 60 %. El cálculo de la composición potencial de las fases presentes en el clinker, al igual que el análisis por IR muestran un predominio de la fase C3S (56.09%, característica que concuerda con la naturaleza de las materias primas. El estudio por IR de los diferentes morteros de ensayo mostró el predominio de la forma amorfa en relación directa con el contenido de puzolana en estos. La resistencia a la compresión presenta finalmente un descenso en relación con el aumento de material puzolánico.

Cement content influence in rebar corrosion in carbonated mortars

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Américo, P. O.

2003-12-01

Full Text Available The cement hydration products protect the concrete rebars of the reinforced concrete due to the production of Ca(OH₂, NaOH, and KOH that, upon dissolving in the concrete s aqueous phase, generate a pH above 12.5. However, reinforced concrete structures are exposed to pollutant gases, such as, CO₂ which upon penetrating the concrete, reacts with the alkaline components, consequently reducing the pH of the aqueous phase causing the loss of passivity by the rebar and as a consequence its corrosion when there is the presence of humidity and oxygen. The objective of the current paper is the analysis of the alkaline reserve influence, measured by the cement content, in the corrosion of rebars employing the polarization resistance technique for determining the corrosion intensity. Results for corrosion intensity of rebars embedded in prismatic mortar test specimens are produced with three cement content levels, with equal water/cement ratio. Cylindrical test specimens were also used for verification of the capillary absorption and the porosity by means of mercury porosymetry The results show that the initiation period is shorter and the corrosion intensity of the rebars is higher when the cement content is lower However, there is also an alteration in the microstructure upon altering the cement content, and far this reason one cannot conclude that the alkaline reserve alone is responsible for these results.

Los productos de hidratación del cemento protegen las armaduras embebidas en el hormigón debido a la gran cantidad de Ca(OH₂, NaOH y KOH disueltos en la fase acuosa del hormigón que proporcionan un pH mayor que 12,5. Sin embargo, las estructuras de hormigón armado están expuestas a los gases contaminantes como el CO₂, que al penetrar en el hormigón reacciona con los compuestos alcalinos, se reduce el pH de la fase acuosa y provocan la despasivación de la armadura. Posteriormente, si hay

Diseños de mezcla de tereftalato de polietileno (pet) - cemento

OpenAIRE

Alesmar, Luis; Rendón, Nalia; Korody, María Eugenia

2008-01-01

Corresponde a este trabajo experimental, la tarea de elaborar, ensayar y caracterizar Mezclas de Tereftalato de Polietileno (PET) - Cemento. Para ello se estableció una metodología basada en una investigación teórico-práctica que ayudase a determinar de manera preliminar el posible comportamiento del plástico proveniente de las botellas de gaseosas al utilizarlo como agregado en una mezcla. Las mezclas de PET - Cemento realizadas están conformadas por 5%, 10% y 15% de PET además de arena y pi...

Adición de nanopartículas al cemento portland

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Jorge Iván Tobón

2007-01-01

Full Text Available En este artículo se presenta la revisión del estado del arte sobre la adición de nanopartículas al cemento Pórtland. Se muestra cómo la nanotecnología está empezando a llegar a este material de construcción buscando generar hormigones de alto desempeño y cómo varios investigadores han incorporado algunos tipos de partículas nanométricas para evaluar fundamentalmente el desempeño físico y mecánico de los cementos adicionados con éstas contra cementos con adiciones de comportamiento más conocido como el humo de sílice, escorias de alto horno y las cenizas volantes. Se encontró que hay una gran expectativa por el efecto positivo de las nanopartículas en el desempeño del cemento, pero que poco se ha trabajado en las posibles modificaciones que ocurren en la mineralogía de las pastas del cemento y en la durabilidad de los morteros a causa de la incorporación de estos nuevos materiales. Además, se identificaron otros vacíos en el conocimiento en este tema como son: la definición de los mecanismos de interacción de las nanopartículas con el cemento Pórtland durante el proceso de hidratación, definición de los porcentajes óptimos de adición de las nanopartículas y su real aporte a las resistencias mecánicas

Cemento-ossifying fibroma.

Science.gov (United States)

Ram, Rangila; Singhal, Anita; Singhal, Parul

2012-01-01

The cemento-ossifying fibroma is classified as a fibro-osseous lesion of the jaws. It commonly presents as a progressively growing lesion that can attain an enormous size with resultant deformity if left untreated. A case of cemento-ossifying fibroma involving the left mandible is described in a 35 year old female patient. The clinical, radiographic and histological features as well as surgical findings are presented. The cemento-ossifying fibroma is a central neoplasm of bone as well as the periodontium which has caused considerable controversy because of the confusion regarding terminology and the criteria for its diagnosis.

El problema de la determinación: del contenido de cemento en morteros; y hormigones fraguados

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Calleja, José

1977-12-01

Full Text Available Se trata en este trabajo de señalar el campo y las condiciones de aplicación del método NELC 5.01-a para determinar la dosificación de cemento en morteros y hormigones fraguados, a la vista de los nuevos tipos de cemento del vigente y reciente Pliego de Prescripciones Técnicas Generales para la Recepción de Cementos (RC-75. Se señalan los grandes errores que se pueden cometer por una inadecuada aplicación del método, y se llama la atención sobre las posibles consecuencias.

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

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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.

Métodos de molienda, granulometría y resistencia desarrollada por los diferentes cementos

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Beke, B.

1961-12-01

Full Text Available Not availableSe han realizado dos series de ensayos para determinar la influencia de las varias fracciones granulométricas en el endurecimiento o desarrollo de resistencias de diferentes cementos.

Ensayos de resistencia a la compresión de bloques de suelo cemento

OpenAIRE

Mas, J. M.; C. Kirschbaum, C.

2011-01-01

El objetivo de este trabajo es determinar la dosificación más adecuada para un determinado tipo de suelo, que se utilizará para fabricar bloques de suelo-cemento, para construir una vivienda en El Puestito, Burruyacu, Tucumán, Argentina. Se extrajeron dos muestras de suelo del área estudiada y se fabricaron probetas de suelo-cemento, utilizando la mezcla de dos muestras a la vez y con cada una por separado. Otra variable introducida fue la presión de fabricación. A los 28 días, fueron en...

Contribución al estudio de los reacciones de hidratación del cemento portland por espectroscopia infrarroja. IV Hidratación del cemento con distintas proporciones de yeso y cloruro cálcico hasta 28 días

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Vázquez, T.

1976-12-01

Full Text Available Not availableSe estudia, a través de los espectros de absorción IR, la hidratación del cemento portland hasta 28 días, considerando como variables su contenido de yeso y la dosis de cloruro cálcico añadida en el agua de amasado. Se comprueba la idoneidad de la técnica, la cual permite observar hechos diferenciales, en función de las variables consideradas. Se puede apreciar una acción antagónica entre el efecto retardador normal del yeso en el fraguado y en la hidratación, y el efecto acelerador del cloruro cálcico, a las dosis y concentraciones en que se produce. Las acciones retardadoras, tanto del yeso como del cloruro cálcico a baja concentración (1% respecto del cemento anhidro, o menor, se atribuyen a la formación predominante de ettringita, mientras que las acciones aceleradoras se explican por la formación preferente de monosulfo-aluminato, cloroaluminato y aluminato tricálcico hidratados. Las conclusiones del trabajo confirman y amplían las previas de otros autores, relativos a aspectos cualitativos y cuantitativos de la influencia del yeso y del cloruro cálcico en las propiedades y en el comportamiento del cemento en la hidratación, así como referentes al mecanismo de ésta.

Cementos con cenizas volantes

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Ossa M., Mauricio

1984-03-01

additions of 20 and 30% .

Casi la generalidad de los estudios realizados sobre cementos con adición de cenizas volantes se refieren a sus características y comportamiento en pastas, morteros y hormigones, siempre en relación con aquéllos del cemento portland. Esta vez, se desarrolló un trabajo experimental orientado a relacionar entre sí los cementos con adiciones de cenizas volantes y de puzolana natural. Para ello se fabricaron a escala de laboratorio cementos de ambos tipos, empleando como materias primas comunes clinker y yeso y, como variables, diferentes porcentajes de las dos adiciones, que cumplieron previamente los requisitos normalizados en cuanto a sus actividades puzolánicas. La calidad de los cementos fabricados resultó adecuada y concordante con la del cemento portland-puzolánico obtenido a escala industrial con los mismos clinker, yeso y puzolana natural de este estudio. Posteriormente, se determinaron las características de los cementos experimentales y se confeccionaron morteros normales para la realización de ensayos físicos y mecánicos. Los resultados de ensayos indicaron que los cementos con adición de cenizas volantes (CCV requieren menos agua para consistencia normal, presentan tiempos de fraguado mayores y expansiones en autoclave menores que los cementos con adición de puzolana (CP. Los calores de hidratación a 7 y 28 días de edad fueron aproximadamente similares para ambos tipos de cemento. En morteros normales, los cementos CCV mostraron menor retracción de secado, mayor retentividad y mayor fluidez (para igual cantidad de agua que los cementos CP. En los ensayos de exudación se observó que ésta depende más de la finura que el tipo de adición. Finalmente, los ensayos mecánicos señalaron que las resistencias a compresión y flexotracción de los morteros con cementos CCV son menores a edades inferiores que 14 días (del orden de 5 a 10% a un día de edad, pero que a partir de entonces pasan a ser mayores que las de

Las nuevas normas españolas para cemento

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Calleja, José

1976-12-01

Full Text Available Not availableSeñores: Es para mí un alto honor, que no es la primera vez que recibo de la fraternal amistad de ustedes los hermanos argentinos, el haber sido invitado por el Instituto Nacional de Tecnología Industrial (INTI con la colaboración del Instituto del Cemento Portland Argentino (ICPA, para departir sobre temas que profesionalmente nos interesan y preocupan.

Elaboración de un cemento óseo de fosfato de calcio con una adición de biovidrio

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Erwin Ciro

2015-03-01

Full Text Available Un cemento óseo se sintetizó a partir CaCO3 y CaHPO4, en un tratamiento térmico a 1.400 °C, el material sintetizado fue enfriado rápidamente, con un chorro de aire. El cemento óseo fue mezclado con biovidrio en un 10% en peso (BC-10BG y luego molido y caracterizado mediante Distribución de Tamaño de Partícula (DTP, Difracción y Fluorescencia de rayos X (DRX y FRX. La mezcla, cemento-biovidrio, y el cemento sólo fueron caracterizados fisicomecánicamente con pruebas de resistencia a la compresión, microdureza, tiempo de cohesión y fraguado. Con el fin de observar tendencias a la precipitación en los estudios in-vitro, se evaluaron adicionalmente otras dos composiciones con biovidrio del 5 y del 15% en peso, por DRX, SEM y FTIR-ATR. Las fases cristalinas encontradas inicialmente corresponden en el cemento óseo al α-TCP, β-TCP, Ca2P2O7 y CaHPO4, por su parte en el biovidrio se detectó, en una parte de su estructura cristalina, la fase whitlockita. En términos físicos, los tiempos de manipulación y las propiedades mecánicas corresponden a un cemento para el relleno de cavidades óseas. Las pruebas in-vitro mostraron un efecto bioactivo progresivo conforme aumenta el tiempo de exposición.

EVALUACIÓN TÉCNICA DE LA RESISTENCIA A COMPRESIÓN EN CONCRETOS ELABORADOS CON CEMENTO TIPO CPCA

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M. Rincon, H. Bolognini,

2016-12-01

Full Text Available En los últimos años en Venezuela se ha presentado una crisis en la demanda, comercialización y producción del cemento, material necesario para la construcción, por lo cual se han venido utilizando cementos adicionados sin ningún tipo de regulación. En este trabajo se presenta la caracterización físico-mecánica de tres mezclas de concreto con relación agua/cemento de 0,45 y relación agua/cemento de 0,60 con diferentes tipos de cemento Portland, Tipo I, Tipo CPCA1, y la tercera mezcla corresponde a Tipo CPCA1 retribuyéndole el 15% de adición en su propio peso, desarrollando una mezcla de mejor calidad. Estos concretos se caracterizaron según: asentamiento, tiempo de fraguado, porcentaje de porosidad total, porcentaje de absorción de agua y resistencia mecánica a la compresión. Los resultados demostraron que la mezcla de concreto elaborada con CPCA1 no cumple con los requisitos mínimos establecidos en la norma venezolana para su uso en la elaboración de concreto estructural, ya que entre otros parámetros su resistencia a la compresión está por debajo del valor de diseño. En cuanto al CPCA1 retribuyéndole el 15% de adición en su propio peso cumple con los requisitos establecidos, y puede ser utilizado en la fabricación de elementos estructurales de concreto.

Procedimiento de estabilizacion de mercurio liquido mediante cemento polimerico de azufre,via sulfuro de mercurio

OpenAIRE

López Gómez, Félix Antonio; López-Delgado, Aurora; Alguacil, Francisco José; Alonso Gámez, Manuel

2009-01-01

Procedimiento para la estabilización de mercurio líquido mediante la obtención de cementos poliméricos de azufre que comprende: (a) transformación del mercurio líquido en sulfuro de mercurio (metacinabrio) mediante reacción química, en condiciones estequiométricas, entre el mercurio y el azufre elemental; y (b) obtención de cemento polimérico de azufre mediante la incorporación el sulfuro de mercurio obtenido en la etapa anterior, en una mezcla estable constituida por áridos, azufre elemental...

Corrosion mitigation of buried structures by soils modification Mitigación de la corrosión de estructuras enterradas mediante la modificación de suelos

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V. C Córdoba

2011-12-01

Full Text Available Carbon steel samples were buried in loamy soil modified with lime, fly-ash and Portland cement in ratio of 5 and 10% during 60 days. Corrosion attack was assessed by electrochemical impedance spectroscopy. Loamy soil without modification was taken as reference. The corrosion products in rust were characterized by Raman spectroscopy. It was found that soil with fly-ash and Portland cement can develop corrosion protection to bare steel due to the changing of formed rust on steel samples. Lepidocrocite and Goethite were found as major constituents in formed rust on buried steel in soil modified with fly-ash and cement, while Magnetite was found informed rust on buried steel in soil without addition of cementitious materials and modified with lime. According to the electrochemical results, the soil with 5% of fly-ash exhibited the anticorrosive best performance.Muestras de acero al carbono fueron enterradas en el suelo arcilloso modificado con cal, ceniza volante y cemento Portland en proporción de 5 y un 10% durante 60 días. El ataque corrosivo fue evaluado mediante espectroscopia de impedancia electroquímica. Muestras de suelo arcilloso sin modificación fueron tomadas como referencia. Los productos de corrosión se caracterizaron por espectroscopía Raman. Se encontró que el suelo con la adición de cenizas volantes y el cemento Portland puede desarrollar protección contra la corrosión del acero desnudo por la modificación del óxido formado sobre muestras de acero. La lepidocrocita y goetita se encontraron como los principales componentes de la herrumbre formada en el acero enterrado en suelos modificados con cenizas volantes y cemento, mientras que la magnetita se encuentra en la herrumbre formada en el acero enterrado en suelo modificado con cal y el suelo sin modificación. De acuerdo con los resultados electroquímicos, el suelo modificado con un 5% de cenizas volantes mostró el mejor desempeño anticorrosivo.

La displasia cemento ósea florida y su diagnóstico diferencial

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Allan Ulisses Carvalho de Melo

2011-09-01

Full Text Available Las lesiones benignas fibro-óseas de los maxilares constituyen un grupo diverso de enfermedades con una característica histológica común: la sustitución de hueso normal por tejido compuesto de colágeno y fibroblastos, con cantidades variables de una sustancia mineral que puede ser de hueso, cemento o ambos. Estas lesiones incluyen la displasia fibrosa, la displasia cemento-ósea en sus variantes: periapical, focal o florida, el cementoma gigantiforme familiar y el fibroma osificante cemento-osificante. La osteomielitis es un proceso inflamatorio agudo o crónico de los espacios medulares o corticales del hueso, que se extiende más allá del sitio inicial de desenvolvimiento. La osteomielitis esclerosante difusa es más frecuente en adultos, principalmente en la mandíbula. Se presenta radiográficamente como una lesión radiopaca difusa adyacente a los dientes, que puede ser multifocal. El objetivo de este trabajo fue describir un caso inusual de lesión fibro-ósea, cuyo diagnóstico diferencial se hizo también con la osteomielitis de los maxilares. Se concluyó que las lesiones fibro-óseas benignas, presentaron muchas similitudes con respecto a sus aspectos clínicos, radiográficos e histológicos. Por lo tanto, es fundamental el análisis conjunto de estas informaciones para obtener un diagnóstico definitivo.

Desarrollo tecnológico de la industria del cemento

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Bogue, R. H.

1963-06-01

Full Text Available Not availableLas fábricas de cemento se han caracterizado durante mucho tiempo por el familiar penacho de polvo que salía por la chimenea. Pero algunas cosas están cambiando y el penacho va desapareciendo. Las razones son varias. Los habitantes de las zonas limítrofes con las fábricas de cemento no soportan el polvo y quieren disfrutar de una atmósfera pura. Los fabricantes se han dado cuenta de que el polvo no es otra cosa sino materia prima que ha sufrido parte del proceso: está completamente homogeneizada, finamente molida, exenta parcialmente de anhídrido carbónico e, inicialmente, contiene una considerable cantidad de calor. También se han dado cuenta que una acumulación de polvo en la fábrica representa un peligro para la salud, para la moral y para la vida de los propios empleados de la misma. Se puede ahorrar tiempo disminuyendo los incidentes o las molestias, se evitan complicaciones judiciales y se puede dar una prueba de buena voluntad. Han comprendido asimismo que la recuperación de polvos es un buen negocio y tiene como consecuencia el de un mayor orden en la fábrica.

Peripheral cemento-ossifying fibroma of maxilla.

Science.gov (United States)

Chatterjee, Anirban; Ajmera, Neha; Singh, Amit

2010-07-01

Peripheral cemento-ossifying fibroma is a reactive gingival overgrowth occurring frequently in anterior maxilla. It is a slow-growing benign tumor which may lead to pathologic migration and other periodontal problems, so it should be excised as soon as possible. The recurrence rate of peripheral cemento-ossifying fibroma is reported to be 8% to 20%, so a close postoperative follow-up is required. Herein, we are reporting a similar case of peripheral cemento-ossifying fibroma in the maxillary anterior region.

Residuo de sanitarios para la elaboración de cementos, procedimiento de obtención y cementos que lo comprenden

OpenAIRE

Sánchez de Rojas, María Isabel; Frías, Moisés; Medina Martínez, César; Asensio, Eloy

2013-01-01

La presente invención describe un residuo obtenido de la industria cerámica de sanitarios o de vertedero o de plantas de reciclaje como componente puzolánico de cementos. Se presenta además un método de obtención de estos residuos de sanitarios y otro procedimiento de fabricación de cementos (cementos comunes y cementos blancos) utilizando estos residuos. Este tipo de residuos, son recogidos directamente en la industria que fabrica cerámica de sanitarios, en vertede...

Influencia de la dosificación en cemento sobre la corrosión de armaduras, negras y galvanizadas provocado por lo penetración de Cl^- en el mortero

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González, J. A.

1981-09-01

Full Text Available Not available

En el presente trabajo se aborda el estudio de la corrosión de armaduras, tanto desnudas como galvanizadas, producida por la penetración de agua de mar en nueve calidades (dosificaciones y por lo tanto porosidades diferentes de mortero de cemento portland en el que se embebieron redondos a tres profundidades (0,5-1,5-2,5 cm. Las probeta de 7 X 7 X 7 cm se conservaron sumergidas durante 1 año. Para la evaluación de la velocidad de corrosión se ha utilizado la Resistencia de Polarización, técnica que permite el seguimiento continuo de la despasivación progresiva que provocan los Cl^- al llegar a la armadura. Se aportan resultados sobre la penetración de Cl^-, discutiéndose las relaciones encontradas entre: corrosión, % de Cl^-, porosidad y dosificación de cemento. Finalmente se compara el comportamiento frente a la corrosión de las armaduras de acero desnudo respecto de las galvanizadas.

Expansive focal cemento-osseous dysplasia.

Science.gov (United States)

Bulut, Emel Uzun; Acikgoz, Aydan; Ozan, Bora; Zengin, Ayse Zeynep; Gunhan, Omer

2012-01-01

To present a case of expansive focal cemento-osseous dysplasia and emphasize the importance of differential diagnosis. Cemento-osseous dysplasia is categorized into three subtypes on the basis of the clinical and radiographic features: Periapical, focal and florid. The focal type exhibits a single site of involvement in any tooth-bearing or edentulous area of the jaws. These lesions are usually asymptomatic; therefore, they are frequently diagnosed incidentally during routine radiographic examinations. Lesions are usually benign, show limited growth, and do not require further surgical intervention, but periodic follow-up is recommended because occasionally, this type of dysplasia progresses into florid osseous dysplasia and simple bone cysts are formed. A 24-year-old female patient was referred to our clinic for swelling in the left edentulous mandibular premolarmolar region and felt discomfort when she wore her prosthetics. She had no pain, tenderness or paresthesia. Clinical examination showed that the swelling in the posterior mandible that was firm, nonfluctuant and covered by normal mucosa. On panoramic radiography and computed tomography, a well defined lesion of approximately 1.5 cm in diameter of mixed density was observed. The swelling increased slightly in size over 2 years making it difficult to use prosthetics and, therefore, the lesion was totally excised under local anesthesia, and surgical specimens were submitted for histopathological examination. The histopathological diagnosis was focal cemento-osseous dysplasia. In the present case, because of the increasing size of the swelling making it difficult to use prosthetics, young age of the patient and localization of the lesion, in the initial examination, cemento-ossifying fibroma was suspected, and the lesion was excised surgically; the histopathological diagnosis confirmed it as focal cemento-osseous dysplasia. We present a case of expansive focal cemento-osseous dysplasia. Differential diagnosis

Desarrollo de nuevos cementos óseos a base de fosfato de calcio: resumen de un estudio piloto

OpenAIRE

Driessens, Ferdinand C. M.; Bermúdez, O.; Boltong, M.G.; Planell Estany, Josep Anton

1994-01-01

Los cementos basados en fosfatos de calcio ofrecen una excelente biocompatibilidad y capacidad para promover el crecimiento óseo, por lo cual son de interés en odontología y ortopedia. El presente trabajo ha conducido hasta la fecha a al elaboración de mas de 500 nuevas formulaciones de cementos de fosfatos de calcio, para las cuales se han medido parámetros tales como tiempo de fraguado y resistencia mecánica. De entre dichas formulaciones se están optimizando las que...

Actividad hidráulica de un cemento belítico obtenido a partir de cenizas volantes tipo C: influencia del aditivo y tipo de curado

OpenAIRE

Goñi Elizalde, Sara; Guerrero Bustos, Ana María

2006-01-01

En este trabajo se discute la influencia del tipo de curado y de un aditivo reductor de la demanda de agua en la actividad hidráulica de un cemento belítico de cenizas volantes de alto contenido en cal denominado (CBCV-2-A). Este cemento ha sido sintetizado por una ruta húmeda hidrotermal con posterior calcinación, empleando ceniza volante de alto contenido en cal (ASTM tipo C) como materia prima. La actividad hidráulica se ha estudiado en la pasta de cemento, durante un periodo de 180 ...

Protection against corrosion to high temperature by means of rich silicon coatings; Proteccion contra corrosion a alta temperatura por medio de recubrimientos ricos en silicio

Energy Technology Data Exchange (ETDEWEB)

Porcayo Calderon, Jesus [Instituto de Investigaciones Electricas, Temixco, Morelos (Mexico)

1999-07-01

In this research work the study of the process of corrosion by molten salts of sodium sulphate-vanadium pentoxide and its prevention by means of metallic coatings rich in silicon was contemplated. The research encompassed the development of the coating system, the chemical and thermochemical analysis of the system sodium sulphate - vanadium pentoxide, the evaluation of the resistance to the corrosion of the coating system by gravimetric and electrochemistry techniques, and the study of the stability of the coating system - substrate. [Spanish] En este trabajo de investigacion se contempla el estudio del proceso de corrosion por sales fundidas de sulfato de sodio - pentoxido de vanadio y su prevencion por medio de recubrimientos metalicos ricos en silicio. La investigacion abarca el desarrollo del sistema de recubrimientos, el analisis quimico y termoquimico del sistema sulfato de sodio - pentoxido de vanadio, la evaluacion de la resistencia a la corrosion del sistema de recubrimientos por tecnicas gravimetricas y electroquimicas, y el estudio de la estabilidad del sistema recubrimiento - sustrato.

[Florid cemento-osseous dysplasia of the jaws].

Science.gov (United States)

Benazzou, S; Boulaadas, M; El Ayoubi, A; Nazih, N; Essakalli, L; Kzadri, M

2011-06-01

Florid cemento-osseous dysplasia is a benign and rare tumor of the jaws. It is more commonly seen in middle-aged black women. Most cases are asymptomatic and are found during routine radiographic examination. We report two complicated cases of florid cemento-osseous dysplasia, one with facial deformity and the other with chronic osteitis. The diagnosis of florid cemento-osseous dysplasia is based on clinical and radiological features. The lesions are commonly bilateral and symmetrical. Copyright © 2011. Published by Elsevier Masson SAS.

Nuevos conglomerantes complementarios del cemento portland

OpenAIRE

Argiz, Cristina; Menéndez, Esperanza; Moragues, Amparo; Sanjuan-Barbudo, Miguel

2012-01-01

El desarrollo de nuevos conglomerantes complementarios al cemento portland se presenta como una alternativa que permitirá reciclar residuos, entre otros posibles beneficios. Estos nuevos materiales difícilmente podrán competir con el cemento portland ya que sus aplicaciones son limitadas y su coste, en general, más elevado.

Equivalencia aproximada entre las resistencias a la compresión de los morteros de cemento Portland según los Pliegos españoles de 1930, 1960 y algunas Normas extranjeras

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Calleja, J.

1961-09-01

Full Text Available Not availableCuando por razones de modernización y puesta al día de las prescripciones y normas de ensayo de un determinado material, por ejemplo el cemento se cambian las especificaciones relativas al mismo, es de todo punto interesante conocer la equivalencia entre las resistencias mecánicas de un mismo cemento ensayado según los métodos antiguos que se abandonan y según los modernos que se adoptan.

Actividad hidráulica de un cemento belítico obtenido a partir de cenizas volantes tipo C: influencia del aditivo y tipo de curado

OpenAIRE

Goñi, S.; Guerrero, A.

2006-01-01

En este trabajo se discute la influencia del tipo de curado y de un aditivo reductor de la demanda de agua en la actividad hidráulica de un cemento belítico de cenizas volantes de alto contenido en cal denominado (CBCV-2-A). Este cemento ha sido sintetizado por una ruta húmeda hidrotermal con posterior calcinación, empleando ceniza volante de alto contenido en cal (ASTM tipo C) como materia prima. La actividad hidráulica se ha estudiado en la pasta de cemento, durante un periodo de 180 días, ...

Normalización del cemento. Resistencias mecánicas: Algunos comentarios sobre el método de ensayo

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Gaspar Tebar, Demetrio

1980-03-01

Full Text Available Not avaible

Como es sabido la categoría de los distintos tipos y clases de los cementos del Pliego de Prescripciones Técnicas Generales para la Recepción de Cementos (RC-75 (1 viene fijada por la resistencia mecánica a compresión, en kp/cm², que como valor mínimo se exige a los 28 días al mortero normal, sin tener un límite máximo; criterio que se sigue en las normas de numerosos países.

Hydrogen sulfide corrosion of weld regions in API X52 steel; Corrosion por acido sulfhidrico de las regiones de soldadura en acero API X52

Energy Technology Data Exchange (ETDEWEB)

Arenas-Martinez, L.F [Universidad Autonoma de Coahuila, Coahuila (Mexico)]. E-mail: fernando.arenas@uadec.edu.mx; Garcia-Cerecero, G. [Corporacion Mexicana de Investigacion en Materiales S.A. de C.V., Saltillo, Coahuila (Mexico)

2012-10-15

The corrosion behavior of gas metal arc welding (GMAW) regions has been studied using potentiodynamic polarization and polarization resistance (LPR) techniques. Experiments were conducted in hydrogen sulfide (H{sub 2}S)-containing brine and in H{sub 2}S-free brine. Welds were made on API 5L X52 steel. Due to differences in their microstructure, chemical composition and residual stress level, weld regions exhibited different responses under H{sub 2}S corrosion. Base metal exhibited the highest corrosion rate (CR) and the most cathodic corrosion potential. [Spanish] Se estudio el comportamiento ante la corrosion de las regiones de soldadura de un cordon realizado por arco metalico con gas (GMAW) sobre un acero grado API X52 mediante las tecnicas de polarizacion potencio dinamica y resistencia a la polarizacion (LPR). Los experimentos se realizaron utilizando salmuera con 300 ppm de acido sulfhidrico (H{sub 2}S) y salmuera libre de H{sub 2}S como electrolitos. Debido a las diferencias en su microestructura, composicion quimica y el nivel de esfuerzos residuales, las regiones de soldadura mostraron diferentes respuestas a la corrosion por H{sub 2}S. El metal base exhibio la velocidad de corrosion (VC) mas alta y el potencial de corrosion mas catodico.

El agrietamiento superficial de las pastas puras de cemento: una interpretación

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Calleja, J.

1964-12-01

Full Text Available Not availableSe aborda por métodos analíticos y técnicas de difracción de rayos X el problema de determinar las posibles causas del agrietamiento superficial de galletas de pasta pura de cemento. Se encuentran diferencias de composición y constitución entre la zona superficial agrietada de las galletas y el resto de la masa, hallándose concordancia entre determinados constituyentes químicos calculados a base del análisis químico y los resultados de difracción de rayos X. Se interpretan estas diferencias como atribuibles a una exudación de lechada de la pasta, con extracción de álcalis solubles y yeso. Como consecuencia, la exudación provoca una carbonatación, una mayor retracción y posiblemente un fraguado acelerado en la zona superficial en relación con la masa interior de las galletas. Como causa directa de la ·exudación se acepta la hipótesis de una granulometría anormal del cemento, probablemente debida a un exceso de finos o gruesos por una molienda grosera, y producida por una deficiencia de tipo mecánico en el proceso de molturación del clínker.

Central Cemento-Ossifying Fibroma: Primary Odontogenic or Osseous Neoplasm?

Science.gov (United States)

Woo, Sook-Bin

2015-12-01

Currently, central cemento-ossifying fibroma is classified by the World Health Organization as a primary bone-forming tumor of the jaws. However, histopathologically, it is often indistinguishable from cemento-osseous dysplasias in that it forms osteoid and cementicles (cementum droplets) in varying proportions. It is believed that pluripotent cells within the periodontal membrane can be stimulated to produce either osteoid or woven bone and cementicles when stimulated. If this is true, cemento-ossifying fibroma would be better classified as a primary odontogenic neoplasm arising from the periodontal ligament. Cemento-ossifying fibromas also do not occur in the long bones. The present report compares several entities that fall within the diagnostic realm of benign fibro-osseous lesions and reviews the evidence for reclassifying central cemento-ossifying fibroma as a primary odontogenic neoplasm. Copyright © 2015 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Cemento-osseous dysplasia in Jamaica: review of six cases.

Science.gov (United States)

Ogunsalu, C; Miles, D

2005-09-01

Six cases of cemento-osseous dysplasia (COD) of the jaw bone in Jamaicans are reviewed. Five were documented over a 15-year period (1980-1995). These include a case of florid cemento-osseous dysplasia (previously called gigantiform cementoma). Three of the initial cases were histologically diagnosed as gigantiform cementoma. There was no indication in the patient's case file whether these were familial or non-familial. The other two cases were diagnosed histologically as periapical cemento-osseous dysplasia and cementoblastoma respectively. Based on the current understanding of the nature of florid-cemento-osseous dysplasia (FLCOD), a new case was diagnosed as such solely on radiological findings. This single case of FLCOD is reported and discussed against the background of other cemento-osseous lesions. Special emphasis is placed on the radiology of COD in this paper. The confirmative role of radiology without the need for histophathology and treatment for asymptomatic FLCOD is emphasized.

Peripheral cemento-ossifying fibroma: case series literature review.

Science.gov (United States)

Verma, Esha; Chakki, Arunkumar Bhimashankar; Nagaral, Sharanbasappa Chandrashekar; Ganji, Kiran Kumar

2013-01-01

THE CONCEPT OF FIBROOSSEOUS LESIONS OF BONE HAS EVOLVED OVER THE LAST SEVERAL DECADES AND NOW INCLUDES TWO MAJOR ENTITIES: fibrous dysplasia and ossifying fibroma. Peripheral cemento-ossifying fibroma is a relatively rare tumour classified between fibroosseous lesions. It predominantly affects adolescents and young adults, with peak prevalence between 10 and 19 yrs. The cemento-ossifying fibroma is a central neoplasm of bone as well as periodontium which has caused considerable controversy because of confusion regarding terminology and the criteria for its diagnosis. The cemento-ossifying fibroma is odontogenic in origin, whereas ossifying fibroma is of bony origin. Lesions histologically similar to peripheral ossifying fibroma have been given various names in existing literature. Therefore, we present and discuss in this paper a series of cases of peripheral cemento-ossifying fibroma emphasizing the differential diagnosis.

Marker of cemento-periodontal ligament junction associated with periodontal regeneration.

Science.gov (United States)

Hara, Ryohko; Wato, Masahiro; Tanaka, Akio

2005-06-01

The purpose of this study was to identify factors promoting formation of the cemento-periodontal ligament junction. Regeneration of the cemento-periodontal ligament junction is an important factor in recovery of the connective tissue attachment to the cementum and it is important to identify all specific substances that promote its formation. To clarify the substances involved in cemento-periodontal ligament junction formation, we produced a monoclonal antibody (mAb) to human cemento-periodontal ligament junction (designated as the anti-TAP mAb) and examined its immunostaining properties and reactive antigen. Hybridomas producing monoclonal antibody against human cemento-periodontal ligament junction antigens were established by fusing P3U1 mouse myeloma cells with spleen cells from BALB/c mice immunized with homogenized human cemento-periodontal ligament junction. The mAb, the anti-TAP mAb for cemento-periodontal ligament junction, was then isolated. The immunoglobulin class and light chain of the mAb were examined using an isotyping kit. Before immunostaining, antigen determination using an enzymatic method or heating was conducted. Human teeth, hard tissue-forming lesions, and animal tissues were immunostained by the anti-TAP mAb. The anti-TAP mAb was positive in human cemento-periodontal ligament junction and predentin but negative in all other human and animal tissues examined. In the cemento-osseous lesions, the anti-TAP mAb was positive in the peripheral area of the cementum and cementum-like hard tissues and not in the bone and bone-like tissues. The anti-TAP mAb showed IgM (kappa) and recognized phosphoprotein. The anti-TAP mAb is potentially useful for developing new agents promoting cementogenesis and periodontal regeneration.

Evaluación de la resistencia a los sulfates de cemento con ceniza volante (utilizando el método de Koch & Steinegger)

OpenAIRE

Irassar, Edgardo F.; Sota, Jorge D.; Batic, Oscar R.

1988-01-01

El aumento del consumo de las adiciones minerales activas en los materiales cementíceos contemporáneos ha determinado la revisión de algunos métodos de ensayo utilizados para determinar sus propiedades. En la evaluación de la durabilidad de los cementos compuestos, muchos ensayos de corta duración (de gran aplicación en cementos portland) dejan de tener validez, pues no permiten evaluar las mejoras que producen los materiales puzolánicos. El método propuesto por KOCH...

[A case report of giant cemento-ossifying fibroma].

Science.gov (United States)

Lu, Run; Liang, Wen-Wu; Yang, Zhan; Liu, Chun-Hai; Zhao, Yue-Tao

2010-12-01

Cemento-ossifying fibroma is a rare benign tumor from periodontium, which usually occurs in mandible body and mandible ramus. It consists of collagen fibrils, fibroblast, and cementoblast. This article reported a case of giant cemento-ossifying fibroma and discussed the clinical features and treatment.

La displasia cemento ósea florida y su diagnóstico diferencial The Florid cemento-bony dysplasia and the differential diagnosis

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Allan Ulisses Carvalho de Melo

2011-09-01

Full Text Available Las lesiones benignas fibro-óseas de los maxilares constituyen un grupo diverso de enfermedades con una característica histológica común: la sustitución de hueso normal por tejido compuesto de colágeno y fibroblastos, con cantidades variables de una sustancia mineral que puede ser de hueso, cemento o ambos. Estas lesiones incluyen la displasia fibrosa, la displasia cemento-ósea en sus variantes: periapical, focal o florida, el cementoma gigantiforme familiar y el fibroma osificante cemento-osificante. La osteomielitis es un proceso inflamatorio agudo o crónico de los espacios medulares o corticales del hueso, que se extiende más allá del sitio inicial de desenvolvimiento. La osteomielitis esclerosante difusa es más frecuente en adultos, principalmente en la mandíbula. Se presenta radiográficamente como una lesión radiopaca difusa adyacente a los dientes, que puede ser multifocal. El objetivo de este trabajo fue describir un caso inusual de lesión fibro-ósea, cuyo diagnóstico diferencial se hizo también con la osteomielitis de los maxilares. Se concluyó que las lesiones fibro-óseas benignas, presentaron muchas similitudes con respecto a sus aspectos clínicos, radiográficos e histológicos. Por lo tanto, es fundamental el análisis conjunto de estas informaciones para obtener un diagnóstico definitivo.The benign fibrous-bony lesions are a diverse group of diseases with common features: replacement of normal bone by tissue composed of collagen and fibroblasts, with variable amounts of a mineral substance that could be bone, cement or both. These lesions include the fibrous dysplasia, the periapical cement-bony dysplasia, focal or florid, familiar giant cementoma and ossifying fibroma (cement-ossifying. Osteomyelitis is an acute or chronic inflammatory process of medullar or cortical spaces of bone extending beyond the onset site of development. Diffuse sclerosing osteomyelitis involves to adults mainly the mandible and

Corrosión de armaduras galvanizadas y sin proteger embebidas en cemento aluminoso estabilizado

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Triviño, F.

1981-06-01

Full Text Available Not available

El cemento aluminoso, cuya obtención se basa en la fusión de bauxita y caliza, ha demostrado desde que fue patentado en Francia, en 1908 por Cementos Lafarge, unas propiedades excepcionales que lo hacen idóneo para ciertas aplicaciones. Tales propiedades son fundamentalmente el desarrollo de elevadas resistencias mecánicas en las primeras edades de hidratación, posibilidad de hormigonar en tiempo frío, una gran resistencia química al agua de mar y a los sulfatos, propiedades refractarias, etc. Todo ello hizo que el cemento aluminoso del tipo fundido, con un 40 % de Al₂O₃, se utilizara ampliamente en la construcción. Sin embargo, a partir de un determinado momento empezaron a observarse alteraciones en algunas obras construidas con hormigón de este tipo, manifestándose importantes pérdidas de sus resistencias mecánicas (1. Las causas de tales deterioros han sido ampliamente estudiadas (2-(13, atribuyéndose la principal a la "conversión" de los aluminatos cálcicos hidratados hexagonales en hidratos cúbicos, según reacción [1].

Focal cemento-osseous dysplasia: review and a case report.

Science.gov (United States)

Salem, Y M Y; Osman, Y I; Norval, E J G

2010-10-01

Focal cemento-osseous dysplasia is a benign fibro-osseous condition that can be seen in dentate and edentulous patients. It is an asymptomatic lesion and needs no treatment; however follow-up is essential due to the possibility that focal cemento-osseous dysplasia can progress to a condition called florid osseous dysplasia that involves multiple sites. A case report is presented here, along with a review of the differential diagnoses considered in order to reach a final diagnosis of focal cemento-osseous dysplasia.

Corrosion detection and monitoring in steam generators by means of ultrasound; Deteccion y monitoreo de corrosion por medio de ultrasonido en generadores de vapor

Energy Technology Data Exchange (ETDEWEB)

Chacon Nava, Jose G; Calva, Mauricio [Instituto de Investigaciones Electricas, Cuernavaca (Mexico); Fuentes Samaniego, Raul [Universidad Autonoma de Nuevo Leon (Mexico); Peraza Garcia, Alejandro [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

1988-12-31

The tube and component failures in steam generators due to corrosion cause huge economical losses. In this article the internal corrosion processes (hydrogen attack) and high temperature corrosion are described, as well as the ultrasound techniques used for its detection. The importance of obtaining corrosion rates, which are fundamental parameters for the detection of the tube`s residual life. The purpose is to prevent possible failures that would diminish the power plant availability. [Espanol] Las fallas de tuberia en componentes de generadores de vapor debidas a corrosion ocasionan considerables perdidas economicas. En este articulo se describen los procesos de corrosion interna (ataque por hidrogeno) y corrosion en alta temperatura, asi como tecnicas de ultrasonido empleadas para su deteccion. Se destaca la importancia de obtener valores de velocidad de corrosion, que es un parametro fundamental para la determinacion de la vida residual de tuberias. El proposito es poder prevenir posibles fallas que disminuyan la disponibilidad de centrales termoelectricas.

Corrosion detection and monitoring in steam generators by means of ultrasound; Deteccion y monitoreo de corrosion por medio de ultrasonido en generadores de vapor

Energy Technology Data Exchange (ETDEWEB)

Chacon Nava, Jose G.; Calva, Mauricio [Instituto de Investigaciones Electricas, Cuernavaca (Mexico); Fuentes Samaniego, Raul [Universidad Autonoma de Nuevo Leon (Mexico); Peraza Garcia, Alejandro [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

1987-12-31

The tube and component failures in steam generators due to corrosion cause huge economical losses. In this article the internal corrosion processes (hydrogen attack) and high temperature corrosion are described, as well as the ultrasound techniques used for its detection. The importance of obtaining corrosion rates, which are fundamental parameters for the detection of the tube`s residual life. The purpose is to prevent possible failures that would diminish the power plant availability. [Espanol] Las fallas de tuberia en componentes de generadores de vapor debidas a corrosion ocasionan considerables perdidas economicas. En este articulo se describen los procesos de corrosion interna (ataque por hidrogeno) y corrosion en alta temperatura, asi como tecnicas de ultrasonido empleadas para su deteccion. Se destaca la importancia de obtener valores de velocidad de corrosion, que es un parametro fundamental para la determinacion de la vida residual de tuberias. El proposito es poder prevenir posibles fallas que disminuyan la disponibilidad de centrales termoelectricas.

en cementos el Cairo S.A.

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ALEXANDER CORREA

2007-01-01

Full Text Available Este artículo tiene como finalidad difundir los estudios de repetibilidad y reproducibilidad de la medida, conocidos como Estudios R&R, a partir del diseño experimental. Con su aplicación se busca identificar y disminuir la variabilidad presente en las mediciones de los ensayos que se realizan en los laboratorios de control de calidad. La efectividad de este tipo de estudios radica principalmente en el control que se haga de las variables que intervienen en los procesos de medición, estas variables son el medio ambiente en que son desarrolladas, el estado de los equipos e implementos utilizados, la capacitación que tiene el operario, el uso de material homogéneo y la aplicación de un método normalizado. El artículo describe una secuencia ordenada de los pasos que se deben seguir antes y durante la realización de un Estudio R&R, además muestra la aplicación de esta metodología en la empresa Cementos El Cairo, donde fueron realizadas dos corridas del método a la prueba finura de cemento, en la primera se identifica la variabilidad presente en los ensayos, de este primer acercamiento surgen algunos ajustes que son implementados rápidamente por la empresa y con el afán de mejorar estos procesos es planeada la segunda corrida, terminado este segundo ciclo se obtiene, aunque en poca proporción, una variabilidad menor a la del primer ciclo.

Normas para la determinación de las resistencias del cemento

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Meyer, A.

1964-09-01

Full Text Available Not availableTodas las normas de cemento contienen disposiciones sobre el ensayo de resistencia, ya que la resistencia constituye, generalmente, la base de la que se parte para determinar la calidad del cemento. Como las normas de los distintos países no suelen ser iguales, el ensayo de un mismo cemento, hecho según cada una de ellas, da unas cifras muy diferentes, lo cual dificulta considerablemente la comparación de la resistencia de un cemento entre los distintos métodos de ensayo.

Cemento-ossifying fibroma of the jaw.

Science.gov (United States)

Katti, Girish; Khan, Mohammed Munnawarulla; Chaubey, Shashi Shanker; Amena, Mehroz

2016-05-12

Cemento-ossifying fibroma is a benign growth, considered to originate from the periodontal ligament. It is often encapsulated and predominantly located in the mandible, and presents as a slow-growing lesion, but may cause deformity if left untreated. The definitive diagnosis of these lesions requires integration of its clinical, radiological and histological features. We present a case of cemento-ossifying fibroma in relation to the lower left one-third of the face, and its management. 2016 BMJ Publishing Group Ltd.

Familial florid Cemento-osseous dysplasia - case report and review of literature.

Science.gov (United States)

Thorawat, Amit; Kalkur, Chaitra; Naikmasur, Venkatesh G; Tarakji, Bassel

2015-12-01

Familial Florid cemento-osseous dysplasia is a very uncommon condition. Cemento-osseous dysplasia is totally asymptomatic in many cases, in those conditions, lesions are detected in a radiograph taken for other purposes. In this report, we describe a family in which mother and daughter exhibited clinical, radiographic, and histologic features of florid cemento-osseous dysplasia.

La Normalización Nacional e Internacional de cementos

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Soria Santamaría, Francisco

1982-12-01

Full Text Available A brief exposition of the situation and tendencies of the cement industry to contemplate its incidence in the development of norms of the conglomerates. Comments are made on the historical development of the norms of cements in Spain and the present situation of the national norms at a world level. Justifying the necessity of an international norm, the participation of ISO and other Bodies is required, emphasizing the requirement of work to be carried out by the Committee TC/51 of the CEN (European Committee of Standardization, in order to achieve a European standard on cements.

Se hace una breve exposición de la situación y tendencias de la industria cementera para contemplar su incidencia en el desarrollo de la normativa de los conglomerantes. Se comenta el desarrollo histórico de la normativa de cementos en España y la situación actual de las normas nacionales a nivel mundial. Justificada la necesidad de una normativa internacional, se cita la participación de ISO y otros Organismos, destacando y precisando la labor llevada a cabo por el Comité TC/51 del CEN (Comité Europeo de Normalización, para conseguir una norma europea sobre cementos.

Focal cemento-osseous dysplasia masquerading as a residual cyst.

Science.gov (United States)

Bhandari, Rajat; Sandhu, Simarpreet V; Bansal, Himanta; Behl, Rashi; Bhullar, Ramanpreet Kaur

2012-04-01

Focal cemento-osseous dysplasia (FCOD) is a benign fibroosseous condition that can be seen in dentulous and edentulous patients. It is an asymptomatic lesion and needs no treatment; however, follow-up is essential due to the possibility that it can progress to a condition called florid cemento-osseous dysplasia. We report a case of FCOD of mandible in a 25-year-old female. Clinically, the lesion resembled periapical pathosis of odontogenic origin. An attempt has been made to discuss the clinical and histopathologic features along with differential diagnosis of cemento-osseous dysplasia.

Focal cemento-osseous dysplasia masquerading as a residual cyst

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Rajat Bhandari

2012-01-01

Full Text Available Focal cemento-osseous dysplasia (FCOD is a benign fibroosseous condition that can be seen in dentulous and edentulous patients. It is an asymptomatic lesion and needs no treatment; however, follow-up is essential due to the possibility that it can progress to a condition called florid cemento-osseous dysplasia. We report a case of FCOD of mandible in a 25-year-old female. Clinically, the lesion resembled periapical pathosis of odontogenic origin. An attempt has been made to discuss the clinical and histopathologic features along with differential diagnosis of cemento-osseous dysplasia.

Dental management of florid cemento-osseous dysplosia.

Science.gov (United States)

Sadda, Raid S; Phelan, Joan

2014-04-01

Cemento-osseous dysplasia encompasses several different clinical and radiographic presentations, including periapical, focal and florid cemento-osseous dysplasia (FCOD). FCOD is usually asymptomatic and discovered only fortuitously. No treatment is required unless the lesion is secondarily infected. Oral hygiene advice should be emphasized for patients with FCOD to prevent caries and periodontal diseases and to maintain natural teeth. Osseointegration of implants would likely not be successful in these patients because the bone is abnormal and not well-vascularized.

Aplicación del análisis por activación neutrónica de gammas inmediatos (PGNAA) para el perfilaje de perforaciones de voladura en una cantera de Cementos Lima: Reporte Preliminar

OpenAIRE

Zanabria, César; Medina, Rafael; Gilvonio, Leoncio; Munive, Marco; Baltuano, Oscar; Solís, José

2008-01-01

El análisis por activación neutrónica de gammas inmediatos (PGNAA) es una técnica de análisis elemental que se usa en la industria. Estamos investigando la factibilidad de la aplicación de la técnica PGNAA en la caracterización elemental de las perforaciones de voladura de la cantera de Atocongo de Cementos Lima. The prompt gamma neutron activation (PGNAA) is a technique that has been used in the industry. We are investigating the feasibility of the PGNAA technique for elemental characteri...

Costillares. Instituto Técnico de la Construcción y del Cemento

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Editorial, Equipo

1958-03-01

Full Text Available El día 8 de febrero de 1958 fueron inaugurados oficialmente por Su Excelencia el Jefe del Estado los nuevos locales e instalaciones del Instituto Técnico de la Construcción y del Cemento. Acompañaban a Su Excelencia los Ministros de Obras Públicas, Educación Nacional, Vivienda, Información y Turismo, Agricultura, Gobernación y Secretario del Movimiento y numerosas personalidades pertenecientes al Consejo Superior y otros Organismos oficiales. Recibió a Su Excelencia el Consejo Técnico Administrativo del Instituto, al frente del cual se encontraba su Presidente, Excmo. Sr. D. Federico Turell, y el Director del Centro, Excmo., Sr. D. Eduardo Torroja. Después de serle presentados los miembros del Consejo, Su Excelencia, en compañía de las diversas personalidades, pasó a visitar las distintas instalaciones: la Planta Piloto y Laboratorio de Artefactos, destinados. a ensayar y estudiar todos los problemas relacionados con la fabricación de cemento, la exposición de prototipos de ventanas, zona de ensayos térmicos y nave de Ensayos Mecánicos. Después pasó a los Laboratorios de Físico-Química, deteniéndose en las Secciones de investigación sobre endurecimiento y fraguado de cementos. Finalmente, y después de visitar la zona de servicios generales y Comedor, pasó a la nave de estudios, Biblioteca y Publicaciones, terminando la visita en el hall principal, donde fué servido un vino español.

Resistencia química del hormigón. XX. Acción del agua de mar: influencia de la adición de escoria a un cemento portland. Estudio por DRX

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Gaspar-Tebar, Demetrio

1983-09-01

Full Text Available In this work, which is a follow-up of others, the evolution of structural features of enriched fraction (attacked-hydrated cement is studied by DRX, extracted from one of the mortar prims (1 : 3 of 1 X 1 X 6 cm of the various series of test specimens made with a Portland cement (cement 3 and mixtures cement 3/slag = 85/15, 65/35, 40/60 and 30/70, in weight, immersed in artificial sea water (ASTM D 1141-75 for 56, 90, 180 and 360 days -at this stage- following curing period (24 hours in humidity saturated enclosure and up to 22 days under filtered drinking water. In addition, structural composition was studied by DRX of the new solid phases formed in the preservation-attack media (artificial sea water where the mortar test pieces were immersed. In the DRX of the various enriched fractions, the peaks of brucite, ettringite and calcite were identified with variable intensity in them all, and those of Friedel salt, plaster and portlandite in part. Intensity of these peaks depends on the mixture used for making the mortar test pieces and on the preservation-attack time. In the DRX of the new solid phases, the peaks of calcite and aragonite were detected with variable intensity, and those of one form prevailed over those of another, depending on system conditions and particularly, on the cement 3/slag mixture used to elaborate the mortar test pieces; the brucite peaks were in addition identified in the diagrams of the solid phases corresponding to media where the mortar test pieces made with cement 3 and the mixture which has 15% slag were immersed.

En el presente trabajo, continuación de otros, se estudia por DRX la evolución de las características estructurales 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 las diversas series de probetas fabricadas con un cemento portland (cemento 3 y con las mezclas cemento 3/escoria = 85/15, 65/35, 40/60 y 30/70, en peso

Imaging in the diagnosis of cemento-ossifying fibroma: a case series.

Science.gov (United States)

Mithra, R; Baskaran, Pavitra; Sathyakumar, M

2012-01-01

Cemento-ossifying fibroma is a benign fibro-osseous lesion belonging to the same category as fibrous dysplasia and cementifying dysplasia. These are slow-growing lesions that are seen in the third and fourth decades of life. Both the ossifying fibroma and cemento-ossifying fibroma represent two extremes of the same disease process since histologically both contain bone and cementum. However, the term cemento-ossifying fibroma is justified on the basis of clinical and radiological correlation. Radiographs have become an essential tool in the diagnosis of lesions in the jaw, where the anatomy is complex. Nowadays, CT provides information for diagnosis as well as treatment planning. In this case series, we report three cases of cemento-ossifying fibroma that were histologically confirmed and discuss the imaging findings.

Evaluación de la susceptibilidad al daño por humedad de mezclas asfálticas empleando propiedades termodinámicas

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Silvia Caro-Spinel

2011-01-01

Full Text Available Este artículo presenta una evaluación comparativa de la susceptibilidad al daño por humedad de diferentes combinaciones de cementos asfálticos producidos en Colombia y agregados pétreos. La metodología empleada se centra en establecer el Índice de Daño por Humedad (IDH de diferentes sistemas cemento asfáltico-agregado. Este índice se calcula con base en propiedades termodinámicas intrínsecas (i.e., energía superfi cial libre de los materiales involucrados. Los resultados obtenidos en este estudio sugieren: (i que el tipo de agregado empleado en mezclas asfálticas tiene mayor infl uencia en la resistencia de la mezcla al ataque del agua que la infl uencia que tiene el cemento asfáltico y (ii que los procesos de modifi cación empleados para producir los diferentes tipos de cemento asfáltico modifi cado conllevan a sistemas cemento asfáltico-agregado con una variada resistencia al daño por humedad. Finalmente, los resultados de este estudio demuestran que la caracterización termodinámica de los materiales de pavimentación puede ser efi cientemente empleada en la selección de materiales durante la etapa inicial del diseño de mezclas asfálticas.

Focal cemento-osseous dysplasia of mandible.

Science.gov (United States)

Cankaya, Abdülkadir Burak; Erdem, Mehmet Ali; Olgac, Vakur; Firat, Deniz Refia

2012-09-03

Fibro-osseous lesions are disturbances in bone metabolism in which normal bone is replaced by a connective tissue matrix that then gradually develops into cemento-osseous tissue. Typically, the lesion is asymptomatic and is detected on routine radiographic examination. Radiologically, this lesion has three stages of maturation: pure radiolucent, radiopaque/mixed radiolucent, and radiopaque appearance. During these stages the lesion can be misdiagnosed. In this case report a 69-year- old patient with a a complaint of painless swelling of the left mandibular molar and premolar area is presented along with a review of the differential diagnoses considered in order to reach a final diagnosis of focal cemento-osseous dysplasia.

Propiedades dieléctricas de pastas de cemento con reducido contenido en agua libre

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de Frutos, J.

1999-12-01

Full Text Available In this work the dielectric properties of concrete with and without chlorides as a function of their water contents were studied by the Electrical Impedance Spectroscopy (EIS. Specimens of cement paste with different water/cement ratio and chlorides content was analyzed. After drying the specimens, the rehydratation was controled by the relative weight increasing. Adetailed study of the dielectric behavior in the range of 20 Hz to 40 MHz according to the water and the chlorides contents was made. The results were discussed in the framework of the material processes.

En el presente trabajo se estudia como varían las propiedades dieléctricas del material con su contenido en humedad de pastas de cemento, con y sin cloruros, mediante la Espectroscopia de Impedancia Electroquímica, EIS. Para ello se fabricaron pastas de cemento con diferentes relaciones agua/cemento, y con diferente contenido de cloruros. Después de someter las muestras a procesos de secado, se procede a la rehidratación de las mismas, controlando el contenido de agua, por medio del incremento en peso relativo. Se hace un estudio pormenorizado de la respuesta eléctrica del material en el rango de 20Hz a 40MHz, en función del contenido de agua, y de la presencia de cloruros, y se relacionan los resultados con los procesos químicos presentes en el material.

Low-grade osteosarcoma arising from cemento-ossifying fibroma: a case report.

Science.gov (United States)

Lee, Yong Bin; Kim, Nam-Kyoo; Kim, Jae-Young; Kim, Hyung Jun

2015-02-01

Cemento-ossifying fibromas are benign tumors, and, although cases of an aggressive type have been reported, no cases of cemento-ossifying fibroma transforming into osteosarcoma have been documented previously. Low-grade osteosarcoma is a rare type of primary bone tumor, representing 1%-2% of all osteosarcomas. A 45-year-old female patient was diagnosed with cemento-ossifying fibroma, treated with mass excision several times over a period of two years and eight months, and followed up. After biopsy gathered because of signs of recurrence, she was diagnosed with low-grade osteosarcoma. The patient underwent wide excision, segmental mandibulectomy, and reconstruction with fibula free flap. The aim of this report is to raise awareness of the possibility that cemento-ossifying fibroma can transform into osteosarcoma and of the consequent necessity for careful diagnosis and treatment planning.

Imaging in the Diagnosis of Cemento-Ossifying Fibroma: A Case Series

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R Mithra

2012-01-01

Full Text Available Cemento-ossifying fibroma is a benign fibro-osseous lesion belonging to the same category as fibrous dysplasia and cementifying dysplasia. These are slow-growing lesions that are seen in the third and fourth decades of life. Both the ossifying fibroma and cemento-ossifying fibroma represent two extremes of the same disease process since histologically both contain bone and cementum. However, the term cemento-ossifying fibroma is justified on the basis of clinical and radiological correlation. Radiographs have become an essential tool in the diagnosis of lesions in the jaw, where the anatomy is complex. Nowadays, CT provides information for diagnosis as well as treatment planning. In this case series, we report three cases of cemento-ossifying fibroma that were histologically confirmed and discuss the imaging findings.

Método complexométrico para el análisis rápido del cemento portland

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Calleja, J.

1964-06-01

Full Text Available Not availableSe aborda en este trabajo el problema del análisis rápido del cemento y de los materiales silíceos por medios puramente químicos y sin la ayuda que pudieran prestar otras técnicas físicas. Se adopta un método volumétrico casi general, basado en la .complexometría, sin más excepción que la determinación gravimétrica acelerada de la sílice. Para la determinación del óxido férrico se mantiene el procedimiento dicromatométrico por su sencillez y precisión. Por complexometría se determinan con Complexona III 0,01 M la suma de alúmina y ácido férrico (la alúmina se calcula por diferencia, la suma de cal y magnesia y, aparte, la cal (la magnesia se calcula por diferencia y el trióxido de azufre. El método se manifiesta tan preciso y reproducible como los clásicos l (dentro de las tolerancias de las Normas A. S. T. M. y es mucho más rápido, puesto que permite efectuar el análisis completo del cemento en unas tres horas. Es también más sencillo, ya que ahorra pesadas y calcificaciones (gravimetrías y no requiere el empleo de equipos especiales de colorimetría, fotometría, espectrometría de rayos X, si bien se conjuga bien con cualquiera de estas técnicas de naturaleza física. Es susceptible de sucesivas mejoras, y en tal sentido se continúa trabajando en el Departamento de Quimica del I.E.T.c.c.

Desarrollo y caracterización de cementos de fosfato de magnesio con propiedades

OpenAIRE

Tayupo, Ruben

2012-01-01

Doble titulació Los cementos de fosfato de magnesio, también conocidos como MPC (Magnesium Phosphate Cements), se obtienen a partir de una reacción ácido-base en medio acuoso, entre un óxido metálico y un fosfato ácido. Esta reacción es muy rápida y exotérmica, lo que permite obtener un material que endurece rápidamente, que tiene buena adhesividad, que adquiere muy buenas propiedades mecánicas a tiempos cortos, y que presenta además un comportamiento antimicrobiano. Por est...

Cemento-ossifying fibroma of maxillary antrum in a young female patient.

Science.gov (United States)

Singhal, A; Ram, R; Singhal, P; Bhatnagar, S; Das, U M

2011-12-01

The cemento-ossifying fibroma is classified as a fibro-osseous lesion of the jaws. It commonly presents as a progressively growing lesion that can attain an enormous size with resultant deformity if left untreated. The cemento-ossifying fibroma is a central neoplasm of bone as well as periodontium which has caused considerable controversy because of controversy regarding terminology and the criteria for its diagnosis. This case report describes a female patient with cemento-ossifying fibroma involving maxillary antrum. The clinical, radiographic and histological features as well as the surgical findings are presented.

Influencia de los materiales cementantes suplementarios sobre la cinética de transporte de agua y las propiedades mecánicas de cal hidratada y morteros de cemento

OpenAIRE

Ince, C.; Derogar, S.; Michelitsch, T. M.

2015-01-01

El objetivo de este artículo es investigar el papel de los materiales cementantes suplementarios (SCMs) en la cinética de transporte del agua y en las propiedades mecánicas de los morteros de cal hidratada (CL90) y cemento Portland. Las propiedades de la cal hidratada son significativamente diferentes a las del cemento y por lo tanto el control de las propiedades de los morteros frescos y endurecidos es fundamental en la optimización mortero/substrato en albañilería. Los parámetros estudiados...

ESTUDIO COMPARATIVO DE PASTAS DE CEMENTO ADICIONADAS CON CATALIZADOR DE CRAQUEO CATALÍTICO USADO (FCC, Y METACAOLIN (MK

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Janneth Torres Agredo

2012-01-01

Full Text Available Este artículo es parte de un proyecto de investigación cuyo objetivo principal es evaluar el desempeño de un residuo de una refinería de petróleo, como adición al cemento Portland con el fin de establecer la viabilidad de su aplicación en materiales de construcción. Este residuo denominado catalizador usado a partir del proceso de craqueo catalítico (fcc procede de las unidades de ruptura catalítica en lecho fluido y está compuesto principalmente por sílice y alúmina. Se analizó la hidratación en pastas de cemento adicionadas con el fcc, y se hizo una comparación con la adición de metacaolín (mk. Para realizar el estudio, se prepararon pastas de cemento Portland Ordinario (opc, adicionadas en porcentajes del 10 y 20% de fcc y mk como reemplazo de cemento. La actividad puzolánica de las adiciones y el tipo de productos de hidratación se determinaron mediante las técnicas de difracción de rayos X (drx y del análisis termogravimétrico (tg/dtg. Como fases principales del proceso de hidratación en las pastas adicionadas con fcc se encontraron silicatos cálcicos hidratados (csh, aluminatos cálcicos hidratados (cah, y silico aluminatos cálcicos (cash, productos similares a los obtenidos en pastas adicionadas con metacaolín.

Giant cemento-ossifying fibroma of the mandible.

Science.gov (United States)

Naik, Raghavendra Mahadev; Guruprasad, Yadavalli; Sujatha, D; Gurudath, Shubha; Pai, Anuradha; Suresh, Kv

2014-01-01

Cemento-ossifying fibroma (COF) is classified as a fibro-osseous neoplasm and included among the non-odontogenic tumors derived from the mesenchymal blast cells of the periodontal ligament, with a potential for forming fibrous tissue, cementum and bone, or a combination of such elements. These are slow-growing lesions, and are more frequent in women between the third and fourth decades of life. Case reports of massive expansile COF, measuring more than 10 cm are rarely reported in the literature. We report a case of giant cemento-ossifying fibroma of the mandible in a 34 year old female patient.

Determinación de sílice libre en materias primas para la industria del cemento

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Calleja, J.

1965-12-01

Full Text Available Not availableLa existencia de sílice libre en las materias primas y, por lo tanto, en los crudos empleados en la fabricación de cemento Portland es desventajosa por la escasa reactividad de esta sílice, sobre todo si no posee una finura suficiente. La determinación de sílice cuarzosa en tales materiales es decisiva para la buena marcha de la clinkerización en fábricas cuyas materias primas adolecen de la desventaja de contenerla. Los métodos propugnados suelen ser poco reproducibles y precisos, y dan resultados bastante erráticos. En el presente trabajo, y después de haber ensayado diversos métodos citados en la bibliografía, se describe y recomienda un procedimiento, basado en el ataque del material por ácido pirofosfórico. Las variables que juegan en el proceso descrito son el tamaño de grano de la muestra, en particular el de la sílice libre, la temperatura y el tiempo de ataque. En las condiciones que se especifican se consigue una disolución prácticamente total de los silicatos, sin que apenas se· disuelvan las partículas más finas de cuarzo. Con ello se consigue una exactitud y una precisión tal como pone de manifiesto el análisis estadístico de los resultados obtenidos al determinar sílice libre en diversas materias primas y crudos para cemento.

Innovación en el sector cementero de Colombia: estudio de caso Cementos Tequendama

OpenAIRE

Jennifer Paola Peña Romero; Moisés Ari Zilber

2015-01-01

El objetivo de este trabajo es interpretar el significado que el personal de la empresa de Cementos Tequen- dama le otorga a la innovación tomando como guía de investigación el Modelo de Innovación del autor Allan Afuah, mediante el estudio de caso y la entrevista en profundidad a informantes clave representados por personal seleccionado en la empresa. Los resultados demuestran que los principales factores que la empresa tiene en cuenta al desarrollar sus procesos de innovación son el análisi...

Methodology for the accelerated simulation of the deterioration that by atmospheric corrosion appears in electronic equipment; Metodologia para la simulacion acelerada del deterioro que por corrosion atmosferica se presenta en equipo electronico

Energy Technology Data Exchange (ETDEWEB)

Ortiz Prado, A.; Schouwenaars, R.; Cerrud Sanchez, S.M. [Facultad de Ingenieria, UNAM, Mexico, D.F. (Mexico)

2002-12-01

The corrosion resistance of systems and electronic parts which are designed to work in atmospheric conditions have been tested for decades; some of these methods were the Cyclic Humidity Test, Field Tests and Salt Spray (Fog) Testing, the latter was one of the most popular methods. However, the salt spray test and most of the other existing methods do not show strong relationships with the real conditions of service. For this reason, it is necessary to develop appropriated methods and equipment for the accelerated simulation of real atmospheric corrosion phenomena. This article seeks to demonstrate the need to develop a test and the necessary equipment to reproduce the damage in electronic systems and equipment by atmospheric corrosion. [Spanish] Para la evaluacion de la resistencia a la corrosion de sistemas y equipo electronico que trabajaran bajo condiciones de deterioro generadas por el medio ambiente, se han aplicado una serie de ensayos, donde el mas popular es el de camara de niebla salina. Sin embargo, este y otros que se han elaborado para tal efecto no tienen ninguna relacion con las condiciones reales de servicio, por lo que es necesario un metodo de evaluacion que permita simular de forma acelerada los fenomenos de deterioro por efectos ambientales. Este articulo pretende demostrar la necesidad de desarrollar una prueba, que en forma acelerada, reproduzca el dano que sufre el material por efecto de la atmosfera; el cual se orienta a la evaluacion de equipo electrico y electronico.

Composición de la pasta de cemento Pórtland (Parte II)

NARCIS (Netherlands)

Brouwers, H.J.H.

2007-01-01

Esta es Ia segunda parte del articulo que revisa el trabajo de Powers y Brownyard (1948) quienes fueron los primeros que investigaron sistemáticamente a reaccion del cemento con el agua y Ia composicion de Ia pasta de cemento.

El cemento natural en el Madrid de los siglos XIX y XX : identificación de sus aplicaciones, estado de conservación y compatibilidad con los cementos actuales

OpenAIRE

Mayo Corrochano, Cristina

2017-01-01

El presente trabajo se centra en el estudio del cemento natural, precursor del cemento Portland, que se empleó históricamente para la ejecución no solo de numerosas obras civiles, sino también en diversos elementos constructivos en edificación (cimentaciones y mortero de junta en un principio, y revestimientos y decoraciones de fachada posteriormente). 1. Antecedentes y fundamentos científicos La producción de cemento natural en España comenzó simultáneamente en el País Vasco y Cataluña en...

Cemento-ossyfying fibroma juvenile of the oral cavity.

Science.gov (United States)

Cecchetti, F; Luciani, F; Bramanti, E; Bartuli, F N; Ottria, L; Arcuri, C

2010-01-01

Fibro-osseous neoplasm remains somewhat controversial, and differing concept have been advanced regarding their nature and the proper terminology for them. Cemento-ossyfying fibroma juvenile (JOF) is a rare type of fibro-osseous tumor as also been included under the "umbrella" of cemento-ossyfying fibroma. The JOF is most often seen in patients who are between 5 and 15 years of age. With this work we emphasize the importance of a correct diagnostic approach. MATERIAL AND METHODS.: The case describes a form of cemento-ossyfying fibroma hight active and aggressive like JOF. The patient thirteen older showed from 2004 to 2008 three times the palatal lesion, it was performed with a incisional biopsy and excisional biopsy. The tumor were fixed in 10% buffered formalin embedded in paraffin cut into thick sections and stained with ematoxylineosin. The incisional biopsy was inadequate to formulate a correct diagnosis. The histological exams have showed for three times different aspects. Some authors in the past have suggested different classification. The COFs show different clinical, histological and radiographical patterns.

DURABILIDAD DEL CEMENTO PORTLAND BLANCO ADICIONADO CON PIGMENTO AZUL ULTRAMAR

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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.

Empleo racional de los cementos para los diferentes tipos de obras

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Calleja, José

1980-12-01

Full Text Available Not available

La tesis del contenido de esta conferencia podría resumirse en los siguientes cinco puntos: 1.º Prácticamente todos los países del mundo que fabrican y utilizan cemento, producen y emplean cementos de distintos tipos, clases y categorías, en relación con las características físicas, químicas y mecánico-resistentes de los mismos. 2:º Todas las obras, estructuras y elementos estructurales de hormigón imponen, en función de sus particularidades intrínsecas —propiedades y características— y extrínsecas — funcionalidad de servicio en las circunstancias ambientales de cada caso—, una serie de condiciones al material hormigón, ya sea masivo, armado o pretensado. 3.º Estas condiciones se refieren, fundamentalmente, a tres parámetros: resistencia mecánica, estabilidad y resistencia química. El conjunto de los tres constituye lo que en términos generales y amplios se puede llamar DURABILIDAD de la obra, esto es, su permanencia en servicio a lo largo del tiempo, y con la garantía de un margen de seguridad suficientemente amplio en todo momento, y en todas las circunstancias reales previsibles de dicho servicio. 4.º Para conseguir la calidad y el comportamiento óptimos de las obras, y con ello la máxima durabilidad de las mismas, es preciso que los componentes del hormigón, sus proporciones y la tecnología del material sean los más adecuados. 5.º Por lo que se refiere en particular al más activo y delicado de los materiales del hormigón, el cemento, éste puede y debe ser el más idóneo en cuanto a tipo, clase y categoría, así como en cuanto a dosificación y modo de empleo, para conseguir los hormigones y las obras más durables en cualquier caso.

Co-occurence of florid cemento-osseous dysplasia and simple bone cyst: a case report.

Science.gov (United States)

Rao, Kumuda Arvind; Shetty, Shishir Ram; Babu, Subhas G; Castelino, Renita Lorina

2011-01-01

The purpose of this report is to present a rare case of co-occurrence of florid cemento-osseous dysplasia with simple bone cyst in a middle aged Asian woman. Most of the reported cases are isolated cases of simple bone cyst or florid cemento-osseous dysplasia, but co-occurrence of these two entities is extremely rare. The authors report a 41 year old female patient with co-occurrence of mandibular florid cemento-osseous dysplasia with simple bone cyst. A thorough clinical and radiological examination was carried out. It was diagnosed mandibular cyst with possible co-occurrence of florid cemento-osseous dysplasia. Surgical exploration of the multilocular lesion was applied. Since, the patient was symptomatic at the time of presentation utmost caution was taken during the surgical procedure as florid cemento-osseous dysplasia is associated with hypo-vascularity of the affected bone. Based on histopathological, as well as supporting clinico-radiological findings a confirmative diagnosis of florid cemento-osseous dysplasia co-occurring with simple bone cyst was made. Patient was followed-up for a period of six months and was reported to be asymptomatic. Timely diagnosis and well planned treatment is important to obtain a good prognosis when a rare co-occurrence of two or more bone lesions affects the jaws.

Residuo cerámico útil para la elaboración de cementos, procedimiento de obtención y cementos que lo comprende

OpenAIRE

Sánchez de Rojas, María Isabel; Frías, Moisés; Asensio, Eloy; Medina Martínez, César

2013-01-01

La presente invención describe un residuo cerámico obtenido a partir de residuos de construcción y demolición como componente puzolánico de cementos. Se presenta además un método de obtención de estos residuos cerámicos y otro procedimiento de fabricación de cementos utilizando estos residuos. Este tipo de residuos, son recogidos en plantas de reciclado, donde se realiza su gestión, con esta invención se podría facilitar una posible salida comercial....

Perfil logístico del sector cemento en Colombia

OpenAIRE

Hernández Calderón, Miguel Ángel; Nieves de la Hoz, Celia Elena

2015-01-01

Este proyecto caracteriza la logística del sector cemento en Colombia al identificar y describir los principales actores, procesos y materiales involucrados en la cadena de suministros del sector. Este documento compila la información logística relevante para la producción de cemento en Colombia. Esta información se obtuvo sintetizando estudios y reportes acerca de las prácticas logísticas y las condiciones en las que éstas se desarrollan. Adicionalmente se realizaron visitas empresariales en...

Determinación del contenido de alúmina reactiva de las adiciones puzolánicas naturales y artificiales, por termogravimetría y por el método de Rietveld

OpenAIRE

Trusilewicz, Lidia Natalia

2014-01-01

Tanto el tema de esta investigación, como sus objetivos, fundamentos, materiales seleccionados y parte experimental para alcanzarlos, han sido promovidos por la situación y el estado de las construcciones de hormigón armado que se comenzaron a realizar en España a partir del año 1975, con hormigones y morteros de cemento que contenían cenizas volantes hasta un 20 %, en principio, y hasta un 35 %, más tarde, de su dosificación de cemento Portland (CP), los cuales y en contra de lo esperado, ha...

EVALUACION DE LA RESISTENCIA A LA CORROSION DEL SISTEMA PRIMER EPOXICO RICO EN ZINC/ACABADO POLISILOXANO POR MEDIO DE ESPECTROSCOPIA DE IMPEDANCIA ELECTROQUIMICA

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ANDRES ALBERTO GUZMAN ROSAS

2011-01-01

Full Text Available En este trabajo fue estudiado el sistema primer epoxico rico en zinc / acabado polisiloxano aplicado sobre laminas de acero al carbono laminado en caliente y sometido a camaras de corrosion acelerada (inmersion total, niebla salina, ciclo de corrosion y prohesion por un periodo de hasta 5000 horas. Las probetas bajo estudio se evaluaron cada 20 dias por medio de espectroscopia de impedancia electroquimica y al final de la prueba se realizaron chequeos visuales y microscopia optica para ver la morfologia de la interface metal-recubrimiento y microespectroscopia Raman para identificar la presencia de posibles productos de corrosion. Los resultados de impedancia fueron simulados por medio de circuitos electricos equivalentes. Para el sistema se encontraron modulos de impedancia del orden de 1011 ¿.cm2 en prohesion, 1010 ¿.cm2 en ciclo de corrosion, 109 ¿.cm2 tanto niebla salina como en las inmersiones totales (NaCl 10-2M y Na2SO4 10-2M. Este sistema tuvo durante el tiempo de pruebas un comportamiento excelente con altas resistencias de pelicula y de transferencia de carga y bajas capacitancias de pelicula y de doble capa.

A case report of cemento-ossifying fibroma.

Science.gov (United States)

Sarwar, Hashmi G; Jindal, M K; Ahmad, Samshad

2010-06-01

The concept of 'fibro-osseous lesions' of bone evolved over the last several decades to include two major entities: fibrous dysplasia and ossifying fibroma as well as the other less common lesions such as florid osseous dysplasia, periapical dysplasia, focal sclerosing osteomyelitis, proliferative periostitis of garrie and ostitis deformans. The cemento-ossifying fibroma is a central neoplasm of bone as well as periodontium which has caused considerable controversy because of confusion of terminology and criteria of diagnosis. The cemento-ossifying fibroma is odontogenic in origin where as ossifying fibroma of bony origin. This article reports a case of an 11-year-old male who came to us with the history of swelling at the maxillary anterior region causing difficulty in closing of mouth as well as mastication.

Cementos de escorias activadas alcalinamente: Situación actual y perspectivas de futuro

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Puertas, F.

1995-09-01

Full Text Available The paper presents the state of the art in cements and concretes with alkaline-activated slag. Characteristics and properties of these materials are given. Special emphasis is made on those scientific and technical aspects which remain unsolved and which, therefore, call for further research.

Se presenta el estado del conocimiento actual de los cementos y hormigones de escorias activadas alcalinamente, detallándose las características y propiedades de los citados materiales. Se incide especialmente en aquellos aspectos de carácter científico y técnico que permanecen sin resolver y que, por tanto, precisan nuevas investigaciones.

Cemento-ossifying fibroma of the mandible. A clinicopathological report.

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Bala, Tapas K; Soni, Sarmeshta; Dayal, Prakriti; Ghosh, Indrajeet

2017-05-01

Cemento-ossifying fibromas are rare fibro-osseous benign neoplasms that affect the jaws. They are included in the group of mesodermal odontogenic tumors and commonly present as a progressively growing lesion that might attain enormous size with resultant deformity, if left untreated. A confusion prevails on the terminology, which can only be confirmed by histopathologic evaluation. A case of cemento-ossifying fibroma involving the right mandible is described in a 30 year-old female patient. The clinical, radiographic, histologic features are presented and the various differential diagnosis are discussed.

Los molinos verticales en la industria del cemento

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Hidalgo de Cisneros Alonso, Juan M.

1977-09-01

Full Text Available Con ocasión de los V Coloquios de Directores y Técnicos de fábricas de cemento tuvimos la oportunidad de exponer a Vds. lo que entonces era una pequeña visión de futuro dentro del marco de la utilización de los molinos verticales o de rodillos para la molienda de crudo de cemento, destinado a la alimentación de hornos de gran producción, y utilizando el calor contenido en los gases de salida para realizar, durante la molienda, y en el interior del molino, el proceso de secado del crudo.

Case presentation of florid cemento-osseous dysplasia with concomitant cemento-ossifying fibroma discovered during implant explantation.

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Gerlach, Robert C; Dixon, Douglas R; Goksel, Tamer; Castle, James T; Henry, Walter A

2013-03-01

A 39-year-old African American woman presented for treatment of a symptomatic mandibular right first molar with a large, periapical radiolucency. After initial attempts at endodontic therapy, this tooth was ultimately extracted owing to unabated symptoms. The extraction site underwent ridge preservation grafting, implant placement, and restoration. After 26 months of implant function, the patient returned with clinical symptoms of pain, buccal swelling, and the sensation of a "loose" implant. This case report details a diagnosis of 2 distinct disease entities associated with the implant site, a cemento-ossifying fibroma and florid cemento-osseous dysplasia of the mandible. This diagnosis was determined from clinical, surgical, radiographic, and histopathologic evidence after biopsy and removal of the previously osseointegrated implant following postinsertion failure by fibrous encapsulation. Before implant therapy, it is essential to conduct a thorough radiographic evaluation of any dental arch with suspected bony lesions to prevent implant failure. Published by Mosby, Inc.

CBCT findings of periapical cemento-osseous dysplasia: A case report

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Eskandarloo, Amir; Yousefi, Faezeh

2013-01-01

Periapical cemento-osseous dysplasia (PCOD) is a subtype of cemento-osseous dysplasia that usually occurs in middle-aged black women. This report described a case of a 45-year-old Iranian woman who was diagnosed with PCOD on the basis of cone beam computed tomographic (CBCT) findings. CBCT enabled detailed visualization of the bone changes. This report described the special radiographic characteristics of PCOD, including discontinuity of the lingual cortex on the CBCT sectional and three-dime...

CBCT findings of periapical cemento-osseous dysplasia: A case report

International Nuclear Information System (INIS)

Eskandarloo, Amir; Yousefi, Faezeh

2013-01-01

Periapical cemento-osseous dysplasia (PCOD) is a subtype of cemento-osseous dysplasia that usually occurs in middle-aged black women. This report described a case of a 45-year-old Iranian woman who was diagnosed with PCOD on the basis of cone beam computed tomographic (CBCT) findings. CBCT enabled detailed visualization of the bone changes. This report described the special radiographic characteristics of PCOD, including discontinuity of the lingual cortex on the CBCT sectional and three-dimensional images.

CBCT findings of periapical cemento-osseous dysplasia: A case report

Energy Technology Data Exchange (ETDEWEB)

Eskandarloo, Amir; Yousefi, Faezeh [Dept. of Oral and Maxillofacial Radiology, Faculty of Dentistry, Hamadan University of Medical Science, Hamadan(Korea, Republic of)

2013-09-15

Periapical cemento-osseous dysplasia (PCOD) is a subtype of cemento-osseous dysplasia that usually occurs in middle-aged black women. This report described a case of a 45-year-old Iranian woman who was diagnosed with PCOD on the basis of cone beam computed tomographic (CBCT) findings. CBCT enabled detailed visualization of the bone changes. This report described the special radiographic characteristics of PCOD, including discontinuity of the lingual cortex on the CBCT sectional and three-dimensional images.

CBCT findings of periapical cemento-osseous dysplasia: A case report.

Science.gov (United States)

Eskandarloo, Amir; Yousefi, Faezeh

2013-09-01

Periapical cemento-osseous dysplasia (PCOD) is a subtype of cemento-osseous dysplasia that usually occurs in middle-aged black women. This report described a case of a 45-year-old Iranian woman who was diagnosed with PCOD on the basis of cone beam computed tomographic (CBCT) findings. CBCT enabled detailed visualization of the bone changes. This report described the special radiographic characteristics of PCOD, including discontinuity of the lingual cortex on the CBCT sectional and three-dimensional images.

Proyecto de una planta industrial de ladrillos ecológicos del tipo suelo-cemento en Arequipa

OpenAIRE

Murillo Salas, Erick Manuel; Murillo Salas, Erick Manuel

2015-01-01

En este trabajo se desarrolló el proyecto de una planta de ladrillos ecológicos en la ciudad de Arequipa. Se fabricó un tipo de ladrillo compuesto de arena-arcilla y reforzado con cemento y se le sometió a tres (3) ensayos de laboratorio para comprobar su resistencia y durabilidad. Actualmente en el Perú no existe ninguna planta para la producción de un ladrillo ecológico por medios industriales. En la ciudad de Arequipa, la gran mayoría de las ladrilleras son artesanales e informales, alg...

Recientes experiencias y tres casos significativos de inspección, diagnóstico y reparación de daños de viguetas prefabricadas con cemento aluminoso

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Delibes, A.

1992-12-01

Full Text Available High Alumina Cement (HAC concrete was used in Spainfrom 1950 to 1970 in the production of prefabricated prestressed joist for floor slab construction, using cement produced by Cementos Molinsfrom 1928 under licence from Lafarge (France. Recent collapses have led to new investigations on buildings under suspicion of having HAC concrete joists. The number of dwelling under suspicion has been evaluated elsewhere in 100,000 in Barcelona and 50,000 in Madrid, these ciphers are, in the authors' opinion, exaggerated. This paper explains INTEMAC’s experiences and methodology for the in-situ inspection, sampling and testing, leading to the corresponding diagnosis and, in some cases a proposal for repair and maintenance practices.

El hormigón de cemento aluminoso se utilizó en España entre los años 50 y 70 para la producción de viguetas de forjado de hormigón pretensado, empleando el cemento, fabricado por Cementos Molins, desde 1928, bajo la licencia francesa de cementos Lafarge. Los daños y hundimientos ocurridos recientemente han conducido a nuevas investigaciones en edificios sospechosos, que han llegado a estimarse en más de 100.000 viviendas en Barcelona y de 50.000 en Madrid, cifras que nos parecen exageradas. Este trabajo expone las experiencias de INTEMAC en los dos últimos años, así como su metodología para la inspección, toma de muestras y ensayos que permiten establecer el correspondiente diagnóstico y la propuesta de refuerzo en su caso.

Central cemento-ossifying fibroma of posterior maxilla

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Uday Shankar Yaga

2015-01-01

Full Text Available Cemento-ossifying fibromas (COFs are relatively rare, benign lesions affecting the jaws and other craniofacial bones and are included in the group of mesodermal odontogenic tumors by Gorlin. They have a predilection for females between the third and fourth decades of life, and about 60% of the lesions are seen most often in the mandibular arch, predominantly occurring in the premolar/molar region of the mandible. This report describes a case of central COF in a 49-year-old male involving the maxillary posterior region. The current case is reported because of the rarity of such lesions and the paucity of information concerning them in the dental literature. We believe that this case illustrates many of the clinical, radiographic, and histologic features associated with cemento-ossifying tumors.

Conservative Management of Central Cemento-Ossifying Fibroma.

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Gomes-Ferreira, Pedro Henrique Silva; Carrasco, Leandro Carlos; de Oliveira, Danila; Pereira, Járede Carvalho; Alcalde, Luis Fernando Azambuja; Faverani, Leonardo Perez

2017-01-01

Central cemento-ossifying fibroma is characterized by the combined production of osteoid and cementoid tissue. Radiographically, this lesion is presented as an outlined cortical and variable radiopaque spots, also can be present complete radiolucent or different degrees of radiopacity. The recommended treatment is curettage or enucleation, and the recurrence rate is less than 5%. Considering that surgical treatment is invasive, mainly in large lesions, this study aims to report a patient in whom conservative treatment was carried out by involving the preservation of teeth, with a long-term follow-up. A 48-year-old black female patient, diagnosed with central cemento-ossifying fibroma in mandible, treated conservatively and a 2 years of follow-up. It was concluded that the conservative treatment with a long term of follow-up for maintaining teeth was satisfactory.

Diseño del sistema scada del proceso de transporte de cemento para holcim-Ecuador

OpenAIRE

Coronel Perez, Ivan Ariolfo; Arreaga Medina, Miguel Angel; Manssur Hanna, Alberto

2009-01-01

Entre los diferentes procesos de fabricación de cemento se encuentra el de transportación del producto y es en este punto en el cual desarrollamos el siguiente proyecto, el mismo tiene por objeto diseñar un sistema automático para operar dicha línea de transporte, empezando en los silos de almacenamiento al granel hasta las máquinas envasadoras desde donde se lo despacha al mercado de consumo. La automatización permitirá a la empresa una operación más veloz y estable del transporte del ...

Resistencia química del hormigón. XIV.- Contribución al estudio del sistema: Cemento P-450-Y hidratado-disolución de sulfato de magnesio

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Bermejo-Muñoz, M. Francisca

1981-12-01

Full Text Available Not available

En el presente trabajo se estudia el comportamiento de un cemento portland industrial resistente al yeso (P-450-Y con un contenido calculado (Bogue nulo de C₃A, del 10,8 % de C₄AF y de 81,7 % de C₃S + C₂S, cuando se somete a la acción de una disolución de sulfato de magnesio, con una concentración de 2,76 g/l de MgSO₄.7 H₂O < > 1,12 X 10^-2 moles/litro de SO₄ (II < > 1,12 X 10^-2 moles/litro de Mg (II, que atraviesa sendos lechos granulados fabricados con dicho cemento, una vez hidratado y curado durante distintos períodos de tiempo, determinando: a La evolución del contenido de iones Ca (II, Mg (II y SO₄ (II en las diversas fracciones recogidas de la disolución de sulfato de magnesio, que han atravesado los lechos de cemento, así como la del pH y de la conductividad. b La variación del contenido de los mencionados iones, que se encuentran formando compuestos, en el cemento de los lechos, cuando se someten a la acción de la mencionada disolución de sulfato de magnesio. c Las modificaciones estructurales experimentadas por los compuestos cristalinos del cemento hidratado de los lechos, sometidos a la acción de dicha disolución de sulfato de magnesio. d La identificación de los compuestos cristalinos de la nueva fase sólida formada en las diversas fracciones recogidas de la disolución de sulfato de magnesio, que atravesaron los lechos de cemento.

Valorización de Cementos Pacasmayo S.A.A.

OpenAIRE

Quispe Alcántara, Jesús; Salvatierra Laura, Elizabeth; Zelada Aliaga, María

2015-01-01

La presente valorización busca determinar el precio de la acción de Cementos Pacasmayo que refleje los fundamentos financieros de la empresa, así como su capacidad de generación de ingresos de acuerdo con sus expectativas de crecimiento. El presente trabajo se divide en nueve secciones. Para valorizar Cementos Pacasmayo, se ha iniciado con la descripción del negocio y se hace un análisis de las características de la empresa, considerando las líneas del negocio, las áreas geográficas y el proc...

Cemento-ossifying fibroma of the mandible.

Science.gov (United States)

Trijolet, J-P; Parmentier, J; Sury, F; Goga, D; Mejean, N; Laure, B

2011-01-01

Cemento-ossifying fibroma is a rare benign tumor most often discovered incidentally. A 72-year-old patient was referred for a subclinical lesion of the mandible. The orthopantomogram showed a well-circumscribed radiolucent osteolytic image, 1 cm in diameter, on the mandibular angle. On CT, the single lesion had a tissue aspect with a peripheral halo without enhancement after contrast injection. A cortical lacuna on the lingual side was noted. Surgical enucleation of the lesion was performed. The pathological examination confirmed the ossifying fibroma. Slow and progressive, cemento-ossifying fibroma is a rare benign tumor that reaches the maxilla and more frequently the mandible. The ossifying and cementifying fibromas are differentiated by their clinical, radiological, and histological findings. The authors discuss the pathogenesis and radiological signs guiding the choice of diagnostic and therapeutic methods. The treatment is surgical with an enucleation or wider resection with bone reconstruction for large fibromas. Copyright © 2010. Published by Elsevier Masson SAS.

Management of symptomatic florid cemento-osseous dysplasia: Literature review and a case report.

Science.gov (United States)

Aiuto, Riccardo; Gucciardino, Federico; Rapetti, Roberta; Siervo, Sandro; Bianch, Andrea-Edoardo

2018-03-01

Cemento-osseous dysplasia is a jaw disorder characterized by a reactive process in which normal bone is replaced by connective tissue matrix. There are different Cemento-osseous dysplasia entities. The treatment of these lesions, once diagnosed by radiology, is not required because generally they are asymptomatic. The localization is in the tooth-bearing areas of the jaws and its distribution is symmetric. In this case report, a 57-year-old Caucasian female patient was referred to our attention complaining of painful inflammatory events localized in the right angle of the jaw. The radiographic appearance, the distribution of several lesions and the positive vitality test of the involved teeth, supported the diagnosis of Florid Cemento-osseous dysplasia. Because of the symptomatology, the patient was submitted to surgery and the lesion and the second inferior right molar were removed. The histological examination of the specimens confirmed the diagnosis. Many lesions that may exhibit a similar sclerotic appearance on conventional radiographs have to be differentiated and dental imaging can be used to discriminate between Florid COD and other lesions. Diagnosis of Florid Cemento-osseous dysplasia can be made with accurate clinical and radiographic assessment. In asymptomatic cases no treatment is required and the patient should have regular follow-up, but in this symptomatic case it was necessary to proceed with surgical intervention. The surgery treatment in the symptomatic case had a favourable prognosis and the two years follow-up has shown a complete healing. Given the abow, it is concluded that the choice of treatment must be selective according to the disease sites. Key words: Cemento-ossifying dysplasia, fibro-osseous lesions, florid cemento-osseous dysplasia, cementoma.

Resistencia química del hormigón. XIII.- Contribución al estudio del sistema: cemento P-450-Y hidratado-disolución de sulfato del sodio

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Sagrera-Moreno, José Luis

1981-12-01

Full Text Available Not available

En el presente trabajo se estudia el comportamiento de un cemento portland industrial resistente al yeso (P-450-Y con un contenido calculado (Bogue nulo de C₃A, del 10,8 % de C₄AF y de 81,7 % de C₃S + C₂S, cuando se somete a la acción de una disolución de sulfato de sodio, con una concentración de 2,1 g/l de Na₂SO₄, < > 1,42 g/l de SO₄ (II < > 1,48 X 10² moles/litro de SO₄ (II, que atraviesa sendos lechos granulados fabricados con dicho cemento, una vez hidratado y curado a edades distintas, determinando: a La evolución del contenido de iones Ca (II y SO₄ (II de las diversas fracciones recogidas de la disolución de sulfato de sodio, que ha atravesado los lechos de cemento, así como la del pH y de la conductividad. b La variación del contenido de los mencionados iones, que se encuentran formando compuestos, en el cemento de los lechos cuando se someten a la acción de la disolución de sulfato de sodio. c Las modificaciones estructurales experimentadas por los compuestos cristalinos del cemento hidratado de los lechos, sometidos a la acción de dicha disolución de sulfato de sodio.

Influencia del yeso sobre la velocidad de hidratación del cemento portland

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Yamaguchi, G.

1961-12-01

Full Text Available Not availablePara esclarecer la Influencia del yeso sobre el fraguado y endurecimiento del cemento, los autores estudiaron el grado de hidratación de los cuatro principales minerales del clínker de cemento Portland y el efecto del yeso sobre ellas. Haciendo uso del análisis cuantitativo de rayos X, se determinó la porción no hidratada. Simultáneamente, se determinaron los tiempos de fraguado y las resistencias. Los ensayos se llevaron a cabo sobre tres clínkeres sintéticos de diferentes composiciones y sobre dos clínkeres de cemento Portland comerciales.

Formulaciones de cemento de fosfato con subproductos de magnesio y su aplicación como material reparador

OpenAIRE

Porta Díaz, Ana

2011-01-01

Los cementos de fosfato, también conocidos como CBPC (Chemically Bonded Phosphate Ceramic), se obtienen a partir de una reacción ácido-base en medio acuoso, entre un óxido metálico y un fosfato ácido. Esta reacción es muy rápida y exotérmica, lo que permite obtener un material que endurece rápidamente, expande ligeramente y que además adquiere muy buenas propiedades mecánicas iniciales. Por estas propiedades, entre otras, resultan muy atractivos para ser empleados en diversas a...

MEJORAMIENTO DE LA EFICIENCIA ENERGÉTICA EN LA INDUSTRIA DEL CEMENTO POR PROCESO HÚMEDO A TRAVÉS DE LA IMPLEMENTACIÓN DEL SISTEMA DE GESTIÓN INTEGRAL DE LA ENERGÍA

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ROSAURA DEL PILAR CASTRILLON

2013-01-01

Full Text Available La tecnología de gestión energética denominada “Sistema de Gestión Integral de la Energía, SGIE” fue propuesta en Colombia en el 2007 como resultado de un proyecto de investigación financiado por el gobierno. Ésta consiste en la aplicación de herramientas estadísticas para el seguimiento de la eficiencia energética en procesos productivos, y de indicadores que se ajustan a los requisitos de la Norma ISO 50001. Este artículo presenta la metodología y los resultados de la implementación del SGIE en una industria de producción de cemento por vía húmeda, los cuales mostraron un incremento de la eficiencia energética asociado a una reducción del consumo de electricidad de 4,6%, logrados sin inversión por compra de nuevos equipos. Es decir, solo con la innovación de los procesos a través de tecnologías de gestión aplicados, además de la adopción de una cultura de manejo de la energía en forma eficiente y de mejoramiento continuo.

A huge cemento-ossifying fibroma of paranasal sinus: a case report.

Science.gov (United States)

Erdim, Ibrahim; Yazici, Zahide Mine; Yilmazer, Rasim; Sever, Nurten; Kayhan, Fatma Tulin

2012-01-01

Cemento-ossifying fibroma is a well-bordered, slow-growing, benign fibro-osseous disease. Although its localization is generally in the mandible, it can be seen in any area of the craniofacial region. Radiology and histopathology help to diagnose the condition. Treatment is based on close observation and/or surgical excision. In this case, we report the case of a 62-year-old male patient who had a large radiological appearance, cemento-ossifying fibroma in the paranasal sinuses.

Concurrent cemento-osseous dysplasia and osteogenic sarcoma: report of two cases.

Science.gov (United States)

Olusanya, A A; Adeyemi, B F; Adisa, A O

2012-01-01

Aim. Cemento-osseous dysplasia (COD) represents a rare group of benign fibroosseous disorders, while osteogenic sarcoma (OS) on the hand, is a malignant tumour of ominous prognosis. A combination of COD and OS is rare and sparsely reported in literature. There are only four reported cases known to the authors. The aim of this paper is to report additional cases of COD occurring concurrently with OS. Materials and Methods. The clinicoradiologic findings and histological analysis of mandibular lesions in two patients who reported at the Dental Centre of the University College Hospital, Ibadan, Nigeria, are presented. Results. The two patients were diagnosed of mandible osteosarcoma occurring concurrently with bilateral mandibular focal cemento-osseous dysplasia. Conclusion. The simultaneous occurrence of osteosarcoma and cemento-osseous dysplasia raises the question of whether COD has transformed into OS or a collision tumour has occurred and their simultaneous occurrence is just a coincidence.

Bases tratadas con cemento, en California

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Chinchilla, M.

1962-05-01

Full Text Available El uso de bases tratadas con cemento para autopistas se inició en el Estado de California en 1938, empleándose para carreteras con determinadas condiciones de tráfico. Inicialmente, se especificó el uso obligatorio de plantas mezcladoras para asegurar el debido control de las proporciones adecuadas.

Peripheral osteoma, compound odontoma, focal cemento-osseous dysplasia, and cemento-ossifying fibroma in the same hemimandible: CBCT findings of an unusual case.

Science.gov (United States)

Borghesi, Andrea; Tonni, Ingrid; Pezzotti, Stefania; Maroldi, Roberto

2017-12-01

Peripheral osteoma is the most common subtype of osteoma that arises most frequently in the craniofacial bones. It may occur at any age with a male-to-female ratio of 2:1. Peripheral osteoma may affect the mandible, particularly the ramus and the condyle. Compound odontoma is a subtype of odontoma that occurs in young subjects without gender predilection. It affects the maxilla more frequently than the mandible. Focal cemento-osseous dysplasia and cemento-ossifying fibroma are 2 benign fibro-osseous lesions with a female predominance that occur most commonly in the posterior region of the mandible. We report the first case involving the simultaneous occurrence of these 4 benign lesions in the same hemimandible diagnosed by CBCT.

DESEMPEÑO DEL CEMENTO PÓRTLAND ADICIONADO CON CALIZAS DE DIFERENTES GRADOS DE PUREZA

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JORGE IVÁN TOBÓN

2008-01-01

Full Text Available En este artículo se determina la incidencia de adicionar calizas de diferentes calidades al cemento Pórtland tipo III, en contraste a la caliza de alta calidad que la empresa Cementos El Cairo S. A., está incorporando a su cemento. Se sustituyó en el cemento 15, 20 y 25% de calizas con títulos (% de CaCO3 80%. Se evaluó la resistencia mecánica de morteros curados bajo condiciones estándar a 3, 7 y 28 días. En pastas se determinó la evolución mineralógica durante el proceso de hidratación usando Difracción de Rayos-X y Análisis Termogravimétrico. Se encontró que las calizas 75% (ASTM C311, estas calizas no presentan actividad puzolánica porque no producen las modificaciones mineralógicas que se esperan de una puzolana.

On the corrosion of reinforcing steels in concrete in the presence of chlorides

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R. Genin, Jean Marie

1986-12-01

Full Text Available The purpose of this study is to give a scientific justification to some empirical results, in steel corrosion field, from concrete containing chlorides. First, it appears that corrosion products on the steels, have different structures and natures in function of the chloride content would be inferior or superior to a characteristic value. Second, the penetration of the chlorides in the concrete can be described by a simple Fick's diffusion law in the most frecuent cases. When cement has a high proportion of tricalcium aluminates and the concrete a small porosity, Fick's law cannot be applied.

Este estudio pretende dar a ciertos resultados empíricos, una justificación científica en el campo de la corrosión de los aceros, en un hormigón que contenga cloruros. En primer lugar, se pone de manifiesto que los productos de corrosión sobre los aceros tienen estructuras y naturalezas diferentes, en función de que el contenido de cloruro sea inferior o superior a un valor característico. En segundo lugar, se puede describir la penetración de los cloruros en el hormigón por una sencilla ley de difusión de Fick, en los casos más frecuentes. Cuando el cemento contiene una elevada proporción de aluminato tricálcico, y el hormigón poca porosidad, no se aplica la ley de Fick.

Propiedades y aplicaciones de los cementos alcalinos Properties and uses of alkali cements

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Ana Fernández-Jiménez

2009-12-01

Full Text Available En este trabajo se presentan algunas de las propiedades tecnológicas de los materiales cementantes elaborados por activación alcalina de aluminosilicatos. Más específicamente sobre las propiedades de morteros y hormigones elaborados con cenizas volantes activadas alcalinamente (sin cemento Portland. Así en función del tipo de activador alcalino empleado y tras un curado térmico previo, el material resultante presentará una interesante lista de propiedades y características que incluyen: elevadas resistencias mecánicas iniciales (a flexión y a compresión, baja retracción al secado, y una muy buena adherencia matriz-acero, así como una excelente resistencia al ataque ácido y un excelente comportamiento frente al fuego. Es por ello que estos nuevos cementos debido a sus magnificas características tecnológicas y durables, así como a la facilidad de adecuarlos a las instalaciones existentes en la industria de los prefabricados, pueden ser fácilmente utilizados en diversas aplicaciones como por ejemplo: elaboración de durmientes para el ferrocarril, bloques para edificación o pavimentación, etc.In this paper are presented some of the technologic properties of cementitious material elaborated by alkali activation of aluminosilicates are presented. More specifically it is about the properties of alkali activated fly ash concrete and mortar (without Portland cement. So depending on the type of alkali activator that is used and after a previous thermal curing, the resulting material will show an interesting list of properties and features that includes: high initial mechanical strengths (under flexure and compression, low drying shrinkage, and a very good matrix-steel bonding, as well as an excellent strength to acid attack and an excellent behaviour when is exposed to fire. That is the reason why these new cements, due to their magnificent and durable technologic features as well as its easy adaptability to the existing

Influencia de los iones Ba2+ y Sr2+ en el proceso de hidratación del cemento portland y de los cementos con adiciones activas

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Živanović, B. M.; Petrašinović, Lj.; Milovanović, T.; Karanović, Lj.; Krstanović, I.

1987-01-01

En el presente trabajo se estudia la influencia de la concentración de los iones Sr2+ y Ba2+ en las aguas de amasado sobre el proceso de hidratación de varios cementos portland y de adición. Se comprueba un incremento de las resistencias mecánicas de dichos cementos, a los 28 días, cuando aumenta la concentración de los iones Ba2+ y Sr2+ en las aguas de amasado, lo cual sugiere una posible explicación microestructural a dicho fenómeno.

Peripheral osteoma, compound odontoma, focal cemento-osseous dysplasia, and cemento-ossifying fibroma in the same hemimandible: CBCT findings of an unusual case

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Andrea Borghesi, MD

2017-12-01

Full Text Available Peripheral osteoma is the most common subtype of osteoma that arises most frequently in the craniofacial bones. It may occur at any age with a male-to-female ratio of 2:1. Peripheral osteoma may affect the mandible, particularly the ramus and the condyle. Compound odontoma is a subtype of odontoma that occurs in young subjects without gender predilection. It affects the maxilla more frequently than the mandible. Focal cemento-osseous dysplasia and cemento-ossifying fibroma are 2 benign fibro-osseous lesions with a female predominance that occur most commonly in the posterior region of the mandible. We report the first case involving the simultaneous occurrence of these 4 benign lesions in the same hemimandible diagnosed by CBCT.

El ahorro de energía en la fabricación de cemento: últimos avances sobre las adiciones puzolanicas

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Talero Morales, Rafael

1986-11-01

Full Text Available This work draws up the operational activities carried out in order to clear the problematic of the behaviour of Pozzolanic Additions -mixed cements made only of Portland Cement (Portland clinker is just a stronger setting regulator, P or PY and pozzolana, this one up to 40% in mass- facing the more or less selenitic means, so as the obtained deductions, conclusions and practical advices and the developed application areas till the end of this wide work (* carried out in this Institute. It also emphasizes the far-reaching that the application of this work will have on Cement and Concrete industries.Se da una rápida panorámica de los planteamientos y actividad operacional llevados a cabo para intentar esclarecer en gran medida esta vasta problemática del comportamiento de las Adiciones Puzolánicas -en forma de Cementos de Mezcla constituidos por Cementos Portland (clinker portland en su caso más regulador de fraguado, P o PY y Puzolana(s únicamente, hasta un 40% en masa de esta(s última(s- frente a distintos medios más o menos selenitosos, así como también de las principales conclusiones, deducciones y consejos prácticos obtenidos y de las aplicaciones desarrolladas a raíz de la finalización oficial de unos densos trabajos (* sobre las mismas, llevados a cabo en este Instituto. Asimismo se hace hincapié de la trascendencia inmediata que las Aplicaciones de tales trabajos, van a tener en las industrias del Cemento y el Hormigón.

Evaluación de impacto ambiental de una molienda de clínker y fábrica de cemento, por el método de escenarios comparados

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Sobrini, I. M.

2006-12-01

Full Text Available This article discusses an environmental impact assessment conducted on a clinker grinding mill and cement plant under development by Terrafield, S.A., in the municipal district of Villasequilla (Toledo.The comparative scenarios approach was chosen as the most suitable methodology for the identification and evaluation of environmental impact in this study. The reference scenario for the comparison was a cement plant presently in operation at La Parrilla (Valladolid, whose technical characteristics are similar to the characteristics of the proposed facility. The data gathered on noise levels and air pollutant emission and immission were supplemented by direct observation of a number of other parameters. Direct comparison not only renders impact identification and evaluation simpler and more objective, but can be used to establish highly effective preventive and corrective measures to ensure that protected areas and the environmental elements of greatest significance are not impacted in any way whatsoever.Este artículo trata sobre la evaluación de impacto ambiental de una Molienda de Clínker y Fábrica de Cemento en Villasequilla (Toledo, promovido por Terrafield S.A.Se escogió para la identificación y valoración de impactos del estudio de impacto ambiental el método de escenarios comparados, a partir de una instalación de cemento de similares características técnicas a la proyectada, actualmente en funcionamiento en La Parrilla (Valladolid, de la que se obtuvieron datos referentes a niveles sonoros, emisión e inmisión de contaminantes atmosféricos y observaciones directas de otros parámetros.Mediante esta comparaci��n directa, no sólo es más objetiva y sencilla la identificación y valoración de impactos, sino que pueden establecerse medidas preventivas y correctoras de eficacia probada en el escenario de comparación, de forma que no se produzca afección alguna sobre los espacios protegidos y elementos del medio de mayor

Cystic Shape Cemento-Ossifying Fibroma of Ethmoid Sinus.

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Shejbal, Dražen; Vonsović, Gabrijela; Baudoin, Tomislav; Vagic, Davor

2015-06-01

Cemento-ossifying fibromas are a group of rarely occurring benign tumours, developing from the periodontal membrane and varying considerably in appearance and in the progress of the disease. Their common feature is higher or lower production of cemental tissue. In most cases the tumours are small because their cementoma mature quickly and become inactive, which causes the tumour to stop growing. They develop most frequently in the mandible and also in the maxilla. Other sites, such as paranasal cavities, soft tissues and bones of the head, are extremely rare. The case of a cemento-fibrosing tumour with psammoma infiltrations, developing from the ethmoid sinus in a nine-year-old girl is reported. Due to frontal headaches and sight defects as well as impaired vision on the right side, NMR was done, which showed a mucocele of the front and rear ethmoid with destruction of the orbital wall and a breakthrough into the orbit. The right maxillary sinus showed a visible retention and a thickened mucous membrane. A rhinoscopy revealed a ball-shaped spherical mass in the medial nasal meatus, which was defined as concha bullosa. An endoscopic examination showed that the tumour protruded in front of the medium nasal concha into the right nasal cavity, softened the ethmoid roof, penetrated toward the base of the skull, adhered and pushed the orbit. It was removed by FESS technique, and PHD revealed subsequently that it was not a mucocele but a cemento-ossifying fibroma.

Influencia del CaF2 sobre la capacidad de reacción de crudos de cemento

OpenAIRE

Palomo, Ángel; Blanco, M. Teresa

1982-01-01

En este trabajo se estudia el efecto de una pequeña cantidad de CaF2 sobre la capacidad de reacción de crudos de cemento, para lo cual se comparan los comportamientos térmicos en función del tiempo de clinkerización de un crudo comercial con y sin adición de CaF2. Se da una estimación de los tiempos necesarios para completar las reacciones a diferentes temperaturas. El efecto mineralizador del espato-fluor pasa por un máximo a temperaturas de clinkerización del orden de 1.200ºC y tiempos d...

Cementos odontológicos a base de Poli (ácido acrílico y wollastonita

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Vargas Gutiérrez, G.

2005-04-01

Full Text Available The glass ionomer cements have been used successfully in dentistry for more than 20 years. A problem of these cements is the release of Al3+ ions to the physiological medium, being able to cause irreversible health problems to the patients. With the purpose of avoiding this problem, cements, from the reaction between the polyacrylic acid and wollastonita (CaSiO3 in a water solution of tartaric acid, have been obtained and characterized. The results have shown that these cements reach compression strength values similar to those of the conventional cements of vitreous polyalqueonate. Additionally, the obtained cements are biocompatibles and bioactives.

Los cementos de polialcanoatos o iomómeros de vidrio son materiales que han sido utilizados con éxito durante más de 20 años en trabajos de odontología. Un problema que presentan dichos cementos es la liberación de iones Al3+ al medio fisiológico, lo que puede dar lugar a daños irreversibles en los pacientes. Con el propósito de evitar dicha liberación, se han preparado y caracterizado cementos obtenidos a partir de la reacción entre el ácido poliacrílico y la wollastonita (CaSiO3 en una solución acuosa de ácido tartárico. Los resultados obtenidos han puesto de manifiesto que estos cementos alcanzan resistencias a la compresión similares a las de los cementos de polialcanoato o ionómeros convencionales. Adicionalmente, los cementos resultantes son biocompatibles y bioactivos.

Cemento-ossifying fibroma in a patient with end-stage renal disease.

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Gopinath, Divya; Beena, V T; Sugirtharaj, G; Vidhyadharan, K; Salmanul Faris, K; Kumar, Sajai J

2013-01-01

The presence of chronic renal disease (CRD) is a predisposing factor for the occurrence of soft and hard tissue lesions in the oral cavity. The cemento-ossifying fibroma (COF) is an uncommon benign fibroosseous lesion composed of fibrocellular component and calcified materials like cementum and woven bone. A 37-year-old female patient undergoing chronic haemodialysis reported to our institution with a complaint of slow growing, nontender swelling of mandible of 6-month duration. Computed tomography disclosed an ill-defined lesion showing thinning and expansion of buccal as well as lingual cortical plate with flecks of radiopacity in centre. Incision biopsy revealed histological characteristics consistent with cemento-ossifying fibroma. The lesion was excised under local anesthesia. The histopathological examination revealed irregularly shaped bone and cementum-like hard tissue calcifications contained within hypercellular fibrous tissue stroma, leading to a confirmation of the diagnosis of cemento-ossifying fibroma. This paper aims to provide light to the fact that the soft and hard tissues of the oral region may become susceptible to the development of pathological growths in case of some particular systemic conditions.

Florid cemento-osseous dysplasia and peripheral giant cell granuloma in a patient with neurofibromatosis 1.

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Sarmento, Dmitry José de Santana; Carvalho, Sérgio Henrique Gonçalves de; Araújo, José Cadmo Wanderley Peregrino de; Carvalho, Marianne de Vasconcelos; Silveira, Éricka Janine Dantas da

2017-01-01

We report a 35-year-old mulatto female patient with neurofibromatosis Type 1 who presented with facial asymmetry. The patient had two lesions: florid cemento-osseous dysplasia associated with peripheral giant cell granuloma. She was referred for surgical treatment of the peripheral giant cell granuloma and the florid cemento-osseous dysplasia was treated conservatively by a multidisciplinary team. So far, no changes have been observed in the patient's clinical status. We observed no recurrence of peripheral giant cell granuloma. To the best of our knowledge, the present case is the first report of a patient with neurofibromatosis Type 1 associated with a giant cell lesion and florid cemento-osseous dysplasia.

A case report of cemento-ossifying fibroma presenting as a mass of the ethmoid sinus.

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Hekmatnia, Ali; Ghazavi, Amirhossein; Saboori, Masih; Mahzouni, Parvin; Tayari, Nazila; Hekmatnia, Farzaneh

2011-02-01

Cemento-ossifying fibroma is a lesion containing both fibrous and osseous components. Such lesions include fibrous dysplasia, ossifying fibroma, cemento-ossifying fibroma and cementifying fibroma. Periodontal membrane is the origin of fibro-osseous lesions other than fibrous dysplasia.Here a clinical case of a young woman referred for evaluation of a mass in the right side of face between eye and nose is presented. The first time she noticed the mass was 2 years ago and was growing larger inwards. She was treated with surgical resection.In this case of a cemento-ossifying fibroma, histological interpretation was critical, and was the basis of correct treatment.

Cemento-ossifying fibroma of the maxilla.

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Al-Shaham, A A; Samher, A A

2010-12-01

Despite the fact that cemento-ossifying fibromas of the maxilla may be quite large and locally aggressive, en-bloc excision is achieved by gentle blunt dissection, with the whole tumour mass peeled out from the adjacent structures. Until recently different fibro-osseous tumours that contained cementum were classified together as "cementomas". In 1992 The World Health Organization adopted a new classification that included these fibromas as benign osseous tumours. While such tumours of the mandible are common, those of the maxilla are rare. They are growth products of periodontal membrane remnant. The triggering mechanism in the formation of cementum outside the periodontal membrane remains unclear. We present a 35-year-old woman who had a giant expanding lobular mass in the right maxilla of 5 years duration. She had visual disturbances and nasal obstruction, and was treated successfully by surgical en-bloc resection of the tumour through an infraorbital transverse incision. The differential diagnosis included fibrous dysplasia, osteoid osteoma, osteoblastoma, chronic sclerosing osteomyelitis, ameloblastoma, squamous cell carcinoma of the maxillary sinus, calcifying epithelial odontogenic tumour (Pindborg tumour) and calcifying odontogenic cyst (Gorlin cyst). Histopathological examination confirmed a cemento-ossifying fibroma.

Morphology of the cemento-enamel junction in premolar teeth.

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Arambawatta, Kapila; Peiris, Roshan; Nanayakkara, Deepthi

2009-12-01

The present study attempted to describe the distribution of the mineralized tissues that compose the cemento-enamel junction, with respect to both the different types of permanent premolars of males and females and the various surfaces of individual teeth. The cervical region of ground sections of 67 premolars that had been extracted for orthodontic reasons were analyzed using transmitted light microscopy to identify which of the following tissue interrelationships was present at the cemento-enamel junction: cementum overlapping enamel; enamel overlapping cementum; edge-to-edge relationship between cementum and enamel; or the presence of gaps between the enamel and cementum with exposed dentin. An edge-to-edge interrelation between root cementum and enamel was predominant (55.1%). In approximately one-third of the sample, gaps between cementum and enamel with exposed dentin were observed. Cementum overlapping enamel was less prevalent than previously reported, and enamel overlapping cementum was seen in a very small proportion of the sample. In any one tooth, the distribution of mineralized tissues at the cemento-enamel junction was irregular and unpredictable. The frequency of gaps between enamel and cementum with exposure of dentin was higher than previously reported, which suggests that this region is fragile and strongly predisposed to pathological changes. Hence, this region should be protected and carefully managed during routine clinical procedures such as dental bleaching, orthodontic treatment, and placement of restorative materials.

Realce textural mediante "desbaste iónico" de muestras pulidas de clínker de cemento portland para estudios por microscopía electrónica de "scanning"

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Rodríguez Rey, Ángel

1985-06-01

Full Text Available Results of using "ion thinning" techniques as final stage in the preparation of polished samples of portland cement clinker for SEM studies are showed. Under proper conditions, flat and clean surfaces are obtained which allow to discriminate textural facts (grain size, form, etc., hardly to see on conventional polished samples due to the similarities of the secondary electron emission of the clinker minerals.

Se estudian los resultados de la aplicación del "desbaste iónico" como etapa final de la preparación de muestras pulidas de clínker de cemento portland para estudios por microscopía electrónica de "scanning". Se observa que, bajo condiciones apropiadas, se obtienen superficies planas y limpias que permiten distinguir rasgos texturales (tamaño, forma y bordes de grano que, dadas las similares características de emisión de electrones secundarios que poseen los minerales del clínker, son de difícil discriminación en secciones pulidas convencionales.

Valorización de la empresa Unión Andina de Cementos S.A.A. (UNACEM S.A.A.)

OpenAIRE

Cárdenas Zúñiga, Julissa Yasmet; Zapana Solórzano, Edson Humberto; Puell Escobedo, Percy Alejandro

2016-01-01

Unión Andina de Cementos S.A.A. (UNACEM S.A.A.) es la cementera líder en el Perú con más de 60 años en el mercado. Es una empresa formada el 25 de julio del 2012 a partir de la fusión de dos empresas cementeras (Cementos Lima fundada en 1967, y Cemento Andino creada en 1952). Su actividad se centra en producir cemento en el Perú y en el extranjero, incluyendo su comercialización y venta. Se muestra el valor de la empresa UNACEM mediante el uso de dos modelos: el método de descuento del flujo ...

Surgical resection of a huge cemento-ossifying fibroma in skull base by intraoral approach.

Science.gov (United States)

Cheng, Xiao-Bing; Li, Yun-Peng; Lei, De-Lin; Li, Xiao-Dong; Tian, Lei

2011-03-01

Cemento-ossifying fibroma, also known as ossifying fibroma, usually occurs in the mandible and less commonly in the maxilla. The huge example in the skull base is even rare. We present a case of a huge cemento-ossifying fibroma arising below the skull base of a 30-year-old woman patient. Radiologic investigations showed a giant, lobulated, heterogeneous calcified hard tissue mass, which is well circumscribed and is a mixture of radiolucent and radiopaque, situated at the rear of the right maxilla to the middle skull base. The tumor expands into the right maxillary sinus and the orbital cavity, fusing with the right maxilla at the maxillary tuberosity and blocking the bilateral choanas, which caused marked proptosis and blurred vision. The tumor was resected successfully by intraoral approach, and pathologic examination confirmed the lesion to be a cemento-ossifying fibroma. This case demonstrates that cemento-ossifying fibroma in the maxilla, not like in the mandible, may appear more aggressive because the extensive growth is unimpeded by anatomic obstacles and that the intraoral approach can be used to excise the tumor in the skull base.

Estructura y propiedades físicas de la pasta de cemento, fraguado

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Powers, T. C.

1959-06-01

Full Text Available Not availableEl propósito que guio al autor, cuando redactó este trabajo fue, según él mismo refiere en su resumen: Dar cuenta de los resultados obtenidos en los estudios iniciados por la «Asociación del Cemento Portland (Portland Cement Ass. Chicago», hace más de 20 años. la autoridad del autor (Director de la Sección de investigaciones básicas en la División de «Investigación y Fomento» de la Asociación ya mencionada, y el haber sido presentado este trabajo al 59 Congreso anual de lo Sociedad Norteamericana de Cerámica como exposición del estado actual de los conocimientos acerca del comportamiento del hormigón, son motivos suficientes paro tratar de presentar en breve espacio las cuestiones que comprende, ya que, tanto más adecuadamente se utilizará el hormigón de portland, cuanto mejor se le conozca, evitándose, por otro parte, las desagradables sorpresas que produce la utilización de un material fuera de los condiciones y limitaciones que le son propios.

Florid cemento-osseous dysplasia and peripheral giant cell granuloma in a patient with neurofibromatosis 1*

Science.gov (United States)

Sarmento, Dmitry José de Santana; de Carvalho, Sérgio Henrique Gonçalves; de Araújo Filho, José Cadmo Wanderley Peregrino; Carvalho, Marianne de Vasconcelos; da Silveira, Éricka Janine Dantas

2017-01-01

We report a 35-year-old mulatto female patient with neurofibromatosis Type 1 who presented with facial asymmetry. The patient had two lesions: florid cemento-osseous dysplasia associated with peripheral giant cell granuloma. She was referred for surgical treatment of the peripheral giant cell granuloma and the florid cemento-osseous dysplasia was treated conservatively by a multidisciplinary team. So far, no changes have been observed in the patient's clinical status. We observed no recurrence of peripheral giant cell granuloma. To the best of our knowledge, the present case is the first report of a patient with neurofibromatosis Type 1 associated with a giant cell lesion and florid cemento-osseous dysplasia. PMID:28538890

Florid Cemento-Osseous Dysplasia Simultaneous the Chronic Suppurative Osteomyelitis in Mandible.

Science.gov (United States)

Cavalcante, Mateus Barros; de Oliveira Lima, Amanda Laísa; Júnior, Marcus Antônio Brêda; Santos, Milkle Bruno Pessoa

2016-11-01

The florid cemento-osseous dysplasia is an uncommon condition nonneoplastic, of unknown cause with higher prevalence in melanodermic women, limited the maxillary bones, is characterized by the presence of dispersed and diffuse radiopaque calcifications, constituted of bone and dense cemento; however, when the bone is infected it induces the suppuration and formation of osseous sequestra, thus resulting in an osteomyelitis frame. The patient was attended in a Dental Specialties Center in the state of Alagoas, Brazil, presenting on clinical examination edema and extra oral fistula with pus drainage in hemiface submandibular of the right side. Radiographically it was possible to observe area of sclerosis and osseous sequestra involving the right side region of the mandible body, and it increases zones of the bone density. In association with clinical data and complementary diagnosis examinations, the option of treatment adopted was the complete removal of the bone fragment, followed by adaptation and plate fixation and titanium screws to reduce the risk of mandibular fracture. The aim of the present paper was to relate a clinical patient of florid cemento-osseous dysplasia simultaneous the chronic suppurative osteomyelitis, highlighting their clinical, radiographic, and histological characteristics, as well as their diagnosis and treatment.

Cemento-Ossifying Fibroma in a Patient with End-Stage Renal Disease

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Divya Gopinath

2013-01-01

Full Text Available The presence of chronic renal disease (CRD is a predisposing factor for the occurrence of soft and hard tissue lesions in the oral cavity. The cemento-ossifying fibroma (COF is an uncommon benign fibroosseous lesion composed of fibrocellular component and calcified materials like cementum and woven bone. A 37-year-old female patient undergoing chronic haemodialysis reported to our institution with a complaint of slow growing, nontender swelling of mandible of 6-month duration. Computed tomography disclosed an ill-defined lesion showing thinning and expansion of buccal as well as lingual cortical plate with flecks of radiopacity in centre. Incision biopsy revealed histological characteristics consistent with cemento-ossifying fibroma. The lesion was excised under local anesthesia. The histopathological examination revealed irregularly shaped bone and cementum-like hard tissue calcifications contained within hypercellular fibrous tissue stroma, leading to a confirmation of the diagnosis of cemento-ossifying fibroma. This paper aims to provide light to the fact that the soft and hard tissues of the oral region may become susceptible to the development of pathological growths in case of some particular systemic conditions.

Durabilidad de un suelo contaminado y tratado con cemento portland Durability of a contaminated soil treated with portland cement

OpenAIRE

José W Jiménez Rojas; Nilo C Consoli; Karla Salvagni Heineck

2008-01-01

Este trabajo tiene por objetivo la aplicación de la técnica de solidificación/estabilización de suelos contaminados, analizando específicamente el comportamiento físico del suelo a través de ensayos de durabilidad. El suelo fue contaminado en laboratorio con residuo oleoso y la aplicación de la técnica tuvo cómo agente de encapsulamiento el cemento Portland CP V-ARI. Los ensayos de durabilidad, realizados según la NBR 13554 (1996), tuvieron como objetivo estudiar el grado de desagregación y v...

Giant cemento-ossifying fibroma of the mandible: a rare case.

Science.gov (United States)

Sujatha, D; Shubha, Gurudath; Anuradha, Pai; Ragavendra, Mahadev Naik

2013-01-01

The World Health Organization classifies cemento-ossifying fibroma (COF) as a fibro-osseous neoplasm included among the nonodontogenic tumors derived from the mesenchymal blast cells of the periodontal ligament, with a potential for forming fibrous tissue, cementum and bone, or a combination of such elements. These are slow-growing lesions, and are more frequent in women, between the third and fourth decades of life. Case reports of massive expansile COFs (measuring more than 10 cm) are rarely reported in the literature. This article aims to describe a case of giant cemento-ossifying fibroma with radiographic and 3D CT features in a 34 year old female patient, who came with the complaint of progressive swelling of the face which had started 6 years earlier.

Central ossifying fibroma, periapical cemento-osseous dysplasia and complex odontoma occurring in the same jaw

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Farzaneh Agha Hosseini

2011-05-01

Full Text Available Central ossifying fibroma is a rare, benign fibro-osseous lesion that arises from the periodontal ligament. Periapical cemento-osseous dysplasia is another variant of fibro-osseous lesion which occurs in the anterior region of the mandible of females. Odontoma is a benign odontogenic tumor that contains enamel, dentine cement and pulp tissue. A 46-year-old woman was referred to the Department of Oral Medicine, School of Dentistry, Tehran University of Medical Sciences, with two nonpainful swellings on both sides of the mandible, which had been slowly growing over a period of one year. Our differential diagnosis was florid cemento-osseous dysplasia, focal cemento-osseous dysplasia for the right side, complex odontoma for the left side and periapical cement-osseous dysplasia for the anterior side. The historical feature revealed ossifying fibroma, complex odontoma and periapical cemento-osseous dysplasia. The occurrence of these three lesions in the same jaw has been rarely reported in the literature. The relationship between the occurrence of these three lesions is not obvious it could be coincidental. It seems that more case reports are needed to establish the relationship between them.

Aspectos Físico-Químicos y Estabilización de los Aluminatos Cálcicos Resultantes de la Hidratación del Cemento Aluminoso

OpenAIRE

Pérez Méndez, Mercedes; Triviño Vázquez, Fernando

1981-01-01

Estudio químico-físico de la estabilización del cemento aluminoso mediante hidratación por encima de 23ºC y carbonatación, con obtención de fases termodinámicamente estables. Estudio de la cinética de hidratación y carbonatación, mediante difracción rayos-X, IR y ATD. Análisis de las resistencias mecánicas a flexo-tracción y compresión.

La industria del cemento dentro de la problemática de la contaminación atmosférica

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Enseñat de Villalonga, Alfonso

1977-09-01

Full Text Available Venir a hablar del cemento en el "Santuario del cemento" como muy bien podría llamarse a este Instituto Eduardo Torreja, es una osadía-sólo permisible a los alquimistas de este preciado material de construcción o a los tecnólogos que dominan y perfeccionan cada día los procesos de producción y amplían el campo de sus aplicaciones. Y más destacable es aún el atrevimiento del conferenciante que acude a unas jornadas que congregan a casi todos los magnates y sabios del cemento.

Florid expansile cemento-osseous dysplasia of the jaws: Cone beam computed tomography study and review of the literature

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Steven R Singer

2017-01-01

Full Text Available An interesting case of florid expansile cemento-osseous dysplasia (FECOD of the maxilla and mandible in a 36-year-old female is being presented. The patient presented for consultation for orthognathic surgery and was unaware of these lesions. Upon clinical and radiographic examination, including cone beam computed tomography, massive cemento-osseous lesions in all quadrants were observed. The radiographic appearance of the lesions was consistent with cemento-osseous dysplasia (COD, the key difference being extreme expansion. Expansion, although not a new phenomenon, is present in all quadrants. These radiographic features suggest a variation of florid cemento-osseous dysplasia and is more aptly termed FECOD. This name is proposed for its diagnostic relevance based on the radiographic features. As with similar CODs, unless the lesions are disfiguring, conservative management is the preferred approach. Biopsy was not indicated unless there are additional associated complications. A detailed review of the pertinent literature was undertaken.

Central ossifying fibroma, periapical cemento-osseous dysplasia and complex odon-toma occurring in the same jaw.

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Hosseini, Farzaneh Agha; Moslemi, Elham

2011-05-16

Central ossifying fibroma is a rare, benign fibro-osseous lesion that arises from the periodontal ligament. Periapical cemento-osseous dysplasia is another variant of fibro-osseous lesion which occurs in the anterior region of the mandible of females. Odontoma is a benign odontogenic tumor that contains enamel, dentine cement and pulp tissue. A 46-year-old woman was referred to the Department of Oral Medicine, School of Dentistry, Tehran University of Medical Sciences, with two non-painful swellings on both sides of the mandible, which had been slowly growing over a period of one year. Our differential diagnosis was florid cemento-osseous dysplasia, focal cemento-osseous dysplasia for the right side, complex odontoma for the left side and periapical cement-osseous dysplasia for the anterior side. The historical feature revealed ossifying fibroma, complex odontoma and periapical cemento-osseous dysplasia. The occurrence of these three lesions in the same jaw has been rarely reported in the literature. The relationship between the occurrence of these three lesions is not obvious it could be coincidental. It seems that more case reports are needed to establish the relationship between them.

Cemento-osseous dysplasia in an elderly Asian male: a case report.

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Komabayashi, Takashi; Zhu, Qiang

2011-03-01

Cemento-osseous dysplasia is a disorder typically found in middle-aged black women. However, the present report describes a case in a 61-year-old Vietnamese male. Without proper pulp testing and diagnosis, the radiographic presentation can easily be misdiagnosed as periapical periodontitis. On the basis of pulp vitality, lack of clinical symptoms and radiographic features, the diagnosis in this case was periapical cemento-osseous dysplasia at the mixed stage, which generally requires no treatment. At the 18-month follow-up, the patient was still asymptomatic and none of the clinical signs had changed. This case highlights the importance of careful clinical examination, including a pulp vitality test, and of having an unbiased view of age, gender, and ethnicity when diagnosing this condition.

Retracción de pastas de cemento en estado plástico y en la primera etapa de endurecimiento

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Cofre, H., Favio

1984-06-01

Full Text Available A great deal of information exists on the retraction occurring in pastes, mortars and concrete, twenty-four hours after being mixed; we have very little information, however, concerning the volumetric changes which take place in a shorter period of time, this being mainly due to the difficulties which arise in measuring these volumetric variations. The authors of this experimental work have been concerned with measuring the short-term changes in volume which take place in cement pastes, that is to say, in periods of less than twenty-four hours, although they have taken measurements for periods of up to three days. Experiments have been carried out on microsamples of 10 X 10 X 40 mm manufactured using the pressing method and kept throughout the measuring period in an isothermic non-aggressive atmosphere. Research has been carried out on four types of cement made up of clinkers of different composition and admixtures of pozzolana or scoria for blast furnaces.

Existen muchos datos sobre la retracción que tiene lugar en las pastas, morteros y hormigones a partir de las veinticuatro horas de su amasado; sin embargo, pocos datos existen de los cambios volumétricos que ocurren por debajo de este tiempo y esto es debido principalmente a las dificultades que se presentan en las medidas de estas variaciones volumétricas. Los autores de este trabajo experimental se han ocupado de las medidas de los cambios de volumen que tienen lugar en las pastas de cemento a corto plazo, es decir, en tiempos por debajo de las veinticuatro horas, aunque en sus medidas hayan llegado hasta los tres días. Los ensayos los han llevado a efecto sobre microprobetas de 10 X 10 X 40 mm fabricadas mediante prensado y conservadas durante el tiempo de las medidas en un ambiente isotérmico y no agresivo. Los estudios se han realizado sobre cuatro tipos de cementos compuestos por clínkeres de diferentes composiciones y adiciones de puzolanas o escorias de horno alto.

8º Congreso Internacional de la Química de los Cementos Comité Científico Euro-Asiático 1ª Reunión del 14 de Septiembre de 1981 en París

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Calleja, Jose

1981-09-01

Full Text Available Not available

En lo que sigue, el autor, asistente por España a la 1.ª Reunión en París del Comité Científico Euro-Asiático para la preparación y organización del 8.° Congreso Internacional de la Química de los Cementos (Río de Janeiro, Julio de 1986, como miembro de dicho Comité, da cuenta, para conocimiento de científicos y técnicos de habla hispana, especialistas o interesados en la Química del Cemento, de los asuntos tratados en la citada Reunión, así como de los acuerdos de principio adoptados en ella.

Cemento adicionado con un residuo del proceso de craqueo catalítico (FCC: hidratación y microestructura

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Silvia Izquierdo

2013-08-01

Full Text Available El presente trabajo estudia el efecto de la incorporación de un residuo procedente de la industria petroquímica denominado catalizador gastado del craqueo catalítico (FCC en la hidratación y microestructura de pastas cementicias. Se utilizan como materiales de referencia, además del cemento portland (OPC, dos tipos de adición de alto desempeño, metacaolín (MK y humo de sílice (HS. La caracterización de los productos de hidratación se realizó por medio de difracción de rayos X (DRX, análisis termogravimétrico (TG, microscopia electrónica de barrido (SEM y resonancia magnética nuclear (NMR. Se complementa este estudio con la evaluación de la resistencia mecánica a compresión de morteros a edad hasta de 90 días. Los resultados indican que los principales productos de hidratación en las pastas adicionadas con FCC son silicato cálcico hidratado (CSH, aluminatos cálcicos hidratados (CAH y silicoaluminatos cálcicos hidratados (CASH. Pastas con 10% de FCC reportan un consumo de cal del 61% a edad de 360 días de curado, valor muy superior al reportado por las adiciones de MK y HS en la misma proporción, esto indica una mayor reactividad del FCC, que incluso se manifiesta a edades tempranas. Cabe anotar que, considerando el factor de dilución, la incorporación de un 10% de FCC como reemplazo del cemento contribuye a la resistencia del material adicionado en órdenes de hasta un 30%. Esto es un indicativo del uso potencial de este residuo como material suplementario en mezclas cementicias.

Viabilidad de la aplicación de materiales reciclados y cenizas de biomasa en la fabricación de materiales tratados con cemento

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Cabrera Montenegro, Manuel

2016-01-01

La presente Tesis Doctoral es una contribución al conocimiento y la investigación sobre el uso de áridos reciclados y cenizas de fondo procedentes de la combustión de biomasa para su uso en ingeniería civil. El interés en el uso de áridos reciclados procedentes de residuos de construcción y demolición (RCD) están en continuo crecimiento debido a su potencial frente a diversos usos, entre ellos como material tratado con cemento para capas estructurales de carretera. Por ot...

Determinación complexométrica de trióxido de azufre en el cemento Portland

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Calleja, J.

1960-12-01

Full Text Available Not availableSe describe un método volumétrico (complexométrico para la determinación cuantitativa del trióxido de azufre en el cemento portland, basado en el ataque de la muestra con ácido nítrico, precipitación del trióxido de azufre con nitrato de plomo, redisolución del precipitado con tartrato sodopotásico amortiguamiento de la disolución a pH = 10 y valoración del plomo por complexometría con EDTA (complexonsa III utilizando como indicador negro de eriocromo T. Los resultados concuerdan con los obtenidos por el método gravimétrico clásico (precipitación del trióxido de azufre con cloruro bárico. La diferencia entre dos valores obtenidos por un mismo operador con la misma muestra, aplicando el método propuesto, están dentro de la tolerancia admitida por las normas A. S. T. M. para el método gravimétrico. La diferencia entre valores volumétricos y gravimétricos correspondientes a una misma muestra también entran dentro de dicha tolerancia. El método descrito tiene la ventaja de ser más rápido, no requerir calcinación y poder ser aplicado por cualquier operador con los medios ordinarios de un laboratorio.

Tentativa de evaluación de los efectos, beneficiosos o perjudiciales, de los aluminatos del cemento sobre las cualidades del hormigón. Primera parte

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Schramll, W.

1979-03-01

Full Text Available El autor expone, en esta primera parte, la cuestión desde el punto de vista del fabricante limitándose a las consecuencias apreciables en las cualidades del hormigón. Trata de responder a dos preguntas: ¿Por qué se debe cambiar el contenido de aluminato tricálcico de un cemento? ¿Qué beneficios, o que perjuicios, producen con el cambio? El objetivo final será poder establecer un análisis "costo-beneficio" correspondiente a cada cambio.

Cemento-ossifying fibroma

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Chandramani More

2011-01-01

Full Text Available Cemento-ossifying fibromas (COFs are benign lesions affecting the jaws and other craniofacial bones. They commonly affect adult females between the third and fourth decade of life, predominantly occurring in the premolar/molar region of the mandible. Most of the lesions typically show slow and often expansile growth, centrally within the jaw and characteristically behave in a benign form, but occasionally they may present as an aggressive gigantiform lesion. Radiographically, they appear as well-defined unilocular or multilocular intraosseous masses. The lesion is invariably encapsulated and of mixed radiolucent densities. The tumor may grow quite extensively; thus, the term "aggressive" is sometimes applied. Surgical resection is the treatment of choice. They are insensitive to radiotherapy and recurrences are uncommon. Clinical, radiographic and histopathologic features of COF and other fibro-osseous lesions are overlapping and may cause confusion in classification, diagnosis and treatment.

Extrusión de cemento sellador endodóntico al espacio periapical

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Landy Solanyi Diaz Canedo

2013-10-01

Full Text Available Resumen La realización de un tratamiento endodóntico tiene como finalidad lograr un buen sellado del conducto para evitar el transporte de contaminantes hacia y desde el conducto radicular, con materiales que presenten en sus características la bioco-mpatibilidad con los tejidos adyacentes. A pesar del uso de localizadores apicales, radiografías y demás elementos auxiliares para un buen diagnóstico y tratamiento por parte del endodoncista, ocasionalmente se presentan situaciones en donde no se respeta el objetivo de mantenimiento de la longitud de trabajo como es el caso de sobre instrumentaciones cuando se intenta retirar instrumentos separados dentro del conducto. Estas permiten la extrusión de materiales de obturación, principalmente cementos selladores causando complicaciones pos-tratamiento como reacciones inflamatorias, afección de las estructuras vecinas (dolor orbital, daño al dentario inferior, dolor de cabeza, etc., e incluso, algunos producen infecciones por aspergilosis en los senos maxilares. Cementos como el AH Plus parecen mostrar resultados favorables aun en casos donde se presenta extrusión de pequeñas cantidades al espacio periapical. Esto se debe a la adición en su composición de aminas epóxicas, que le permiten minimizar la liberación de toxinas y según algunos autores, los posibles efectos citotóxicos cesan una vez se endurece el material. (DUAZARY 2011, 88 - 92AbstractThe importance of endodontic treatment is to achieve a complete filling and sealing of the root canal to prevent the transport of contaminants to and from root canal, with materials compatible with the surrounding tissues. Occasionally a situation may arise in which the purpose of the maintenance of working length is compromised such as overenlargement. This situation allows the extrusion of filling materials, mainly sealer cements, causing post treatment complications such as inflammatory reactions, injury to adjacent structures (orbital

Caracterización funcional de la cohesión de los cementos asfálticos utilizados en Chile mediante el porecedimiento UCL®

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Valdés Vidal, Gonzalo A.; Calabi, Alejandra; Miró Recasens, José Rodrigo; Osses, Rodrigo

2013-01-01

Una de las principales propiedades que debe poseer el ligante de las mezclas asfálticas para aumentar su durabilidad en los pavimentos, es la cohesión. En Chile, pese a la diversidad climática imperante a lo largo de su territorio y a la importancia que tiene la cohesión proporcionada por el cemento asfáltico en la matriz árido-ligante en el comportamiento estructural de la mezcla asfáltica, esta propiedad no se considera habitualmente en las fases de diseño de la mezcla. En este contexto, es...

Comparison between the corrosion forecast based on the potential measurement and the determination of the corrosion rate of the reinforcement bar by means of electrochemical techniques

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Castaneda, A.

2003-12-01

Full Text Available The ASTA4 876-91 standard establishes a corrosion forecast of concrete reinforced bar by measuring the electrochemical potential. This forecast is based on thermodynamic considerations without taking into account the kinetic of the corrosion process. A comparison was made between the results obtained based on this standard and others using electrochemical techniques (Tafel, Rp, EIS, Electrochemical Noise. These techniques allows to obtain the corrosion rate in samples having 0.4, 0.5 and 0.66 water/cement ratios submitted to salt spray outdoors and by immersion in 3% saline solution during a test time of 20 months. Differences were detected between the results obtained using the ASTM standard and the electrochemical techniques used. The main difference is that samples submitted to immersion shows a higher probability of corrosion than samples submitted to salt spray; however, the electrochemical techniques showed the contrary concerning the corrosion kinetic process .A comparison respecting corrosion rate was also made between the results obtained by the different electrochemical techniques. It is very well known that all electrochemical techniques supposed always general corrosion except electrochemical noise. Using the technique the pitting index can be calculated. It shows that localized corrosion is the most predominant

La norma ASTM 876-91 establece un pronóstico de corrosión de la barra de refuerzo del hormigón armado mediante la determinación de potenciales electroquímicos. Este pronóstico se basa en consideraciones termodinámicas, sin tener en cuenta la cinética del proceso de corrosión. Se comparan los resultados obtenidos aplicando esta norma con técnicas electroquímicas (Tafel, Rp, EIS, Ruido Electroquímico que permiten calcular la velocidad de corrosión en probetas con relaciones agua/cemento 0,4, 0,5 y 0,66 sometidas a niebla salina en condiciones naturales y en inmersión en solución salina al 3% durante un

Influencia de la incorporación de un co-monómero alcalino e hidroxiapatita en las propiedades de cementos óseos acrílicos

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Karen Lozano

2013-01-01

Full Text Available Se formularon cementos óseos acrílicos utilizando una relación sólido / líquido de 2. El componente líquido se basó en metacrilato de metilo (MMA, como monómero y dimetil-p-toluidina (2.5% como acelerador; a su vez, el componente sólido consistió en perlas de polimetacrilato de metilo (PMMA como carga, sulfato de bario como agente radiopaco y peróxido de benzoilo (2% como iniciador. Finalmente, una hidroxiapatita como carga bioactiva y un metacrilato de dimetil amino etilo (DMAEM como co-monómero alcalino, fueron incorporados en diferentes porcentajes (0-20% p/p, para el primero y 0-10% p/p, para el segundo. Como era de esperarse, las muestras elaboradas con las formulaciones de cementos óseos acrílicos sin modificar, presentaron calores de reacción elevados (>80ºC y una resistencia a la compresión (124.0 MPa por encima de lo especificado en la norma ISO 5833. Con la incorporación de la hidroxiapatita y el co-monómero alcalino, se presentaron bajas temperaturas de polimerización, bajos módulos y resistencias mecánicas, así como la fijación de una capa similar a la apatita biológica en la superficie del material después de su inmersión por 30 días en un fluido biológico simulado.

En bloc resection of huge cemento-ossifying fibroma of mandible: avoiding lower lip split incision.

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Ayub, Tahera; Katpar, Shahjahan; Shafique, Salman; Mirza, Talat

2011-05-01

Cemento-ossifying Fibroma (COF) is an osteogenic benign neoplasm affecting the jaws and other craniofacial bones. It commonly presents as a progressively slow growing pathology, which can sometimes attain an enormous size, causing facial deformity. A case of a huge cemento-ossifying fibroma, appearing as a mandibular dumbell tumour in a male patient is documented, which caused massive bone destruction and deformity. It was surgically removed by performing en bloc resection of mandible avoiding the splitting of lower lip incision technique, thereby maintaining his normal facial appearance.

Introducción a la fabricación y normalización del cemento portland

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Sanjuán Barbudo, Miguel Ángel; Chinchón Yepes, Servando

2014-01-01

El cemento portland es un conglomerante hidráulico cuya principal propiedad es la de formar masas pétreas resistentes y duraderas cuando se mezcla con áridos y agua. El endurecimiento de la mezcla ocurre transcurrido un cierto tiempo desde el momento en que se realiza el amasado, lo que permite dar forma a la piedra artificial resultante. Estas tres cualidades (moldeable, resistente, duradero) hacen que los productos derivados del cemento tengan una gran aplicación en la construcción de edifi...

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

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Talero Morales, Rafael

1993-09-01

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

Comportamiento de un cemento portland resistente a los sulfatos frente al agua desionizada y a disoluciones de sulfato de sodio y de sulfato de magnesio

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Bermejo-Muñoz, M. Francisca

1987-12-01

Full Text Available Not available

[es] En este trabajo se estudia el comportamiento de un cemento portland industrial resistente a los sulfatos cuando los lechos granulados —fabricados con dicho cemento, una vez hidratado y conservado durante 7 y 28 días en una cámara húmeda a 21 ± 2 °C y con una humedad relativa superior al 90%— se someten a la acción del agua desionizada, de una disolución de sulfato de sodio y de otra disolución de sulfato de magnesio habiendo determinado: a. la evolución de los contenidos de los iones Ca (II y SO₄ (II en los dos primeros casos, y además Mg (II, en el tercero, en las disoluciones que han atravesado los lechos de cemento, así como la del pH y de la conductividad, b. la variación del contenido de los iones mencionados en los compuestos correspondientes del cemento de los lechos, una vez sometidos a la acción de las disoluciones agresivas, así como las modificaciones estructurales experimentadas, y c. las características estructurales de la nueva fase sólida formada en las fracciones recogidas de la disolución de sulfato de magnesio, que han atravesado los lechos de cemento. En estos trabajos se ha puesto de manifiesto que la cantidad de Ca(OH₂ disuelta (extraída tanto por el agua desionizada, como por la disolución de sulfato de sodio, disminuye exponencialmente a medida que aumenta el volumen de estas disoluciones, que han atravesado los lechos de cemento, alcanzando un valor asintótico; este fenómeno influye en el avance de las reacciones de hidratación y en la degradación de los compuestos del cemento. En el caso de la disolución de sulfato de magnesio, se produce un intercambio entre los iones Ca (II del Ca(OH₂ del cemento hidratado y el Mg (II de la disolución, el cual precipita como brucita en el lecho —llegando a colmatarlo en determinados casos— y en las fracciones de la disolución que han atravesado los lechos. La disolución del Ca(OH₂

Determinación volumétrica de la sílice en el cemento Portland

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Calleja, J.

1966-09-01

Full Text Available Not availableSe describe un método volumétrico para la determinación cuantitativa de la sílice en el cemento portland, basado en la precipitación de la misma como fluorosilicato potásico, hidrólisis de esta sal insoluble en las condiciones de ensayo y valoración del ácido fluorhídrico liberado, con una disolución de hidróxido sódico. El método da valores reproducibles con muy escasa dispersión. La diferencia entre los valores más dispares de series de diez determinaciones hechas en una misma muestra por el mismo operador, son del orden de la tolerada por las normas A.S.T.M. (método gravimétrico para valores de un mismo operador obtenidos sobre una muestra. La diferencia entre cualesquiera otros dos valores de las series, o entre uno cualquiera de ellos y la media correspondiente a dicha serie, es muy inferior al margen de tolerancia de la A.S.T.M. Finalmente, entre el valor gravimétrico según el método de las normas A.S.T.M. y los valores volumétricos obtenidos por el método descrito, a la media de ellos, existe una concordancia aceptable.

Findings of florid cemento-osseous dysplasia: a report of three cases.

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Köse, Taha Emre; Köse, Onur Dincer; Karabas, Hulya Cakir; Erdem, Tamer Lutfi; Ozcan, Ilknur

2013-10-01

Florid cemento-osseous dysplasia (FCOD) is a benign jaw lesion originating from periodontal ligament tissues usually asymptomatic and diagnosed accidentally at routine dental radiographic examination. The purpose of this paper is to report three cases diagnosed as FCOD with their clinical, radiographic and histological findings. Radiologic and clinical symptoms of three cases diagnosed as FCOD are presented. Serum alkaline phosphatase test and biopsy taken from two of the patients are discussed to eliminate the Paget's disease. Three patients diagnosed as FCOD and called for routine follow-up. Because of no sign of infection or osteomyelitis, conservative treatment was applied. Radiographic examination is significant for the diagnosis of florid cemento-osseous dysplasia, especially in the asymptomatic cases. The roles of the dentist are to ensure the follow-up of the diagnosed patients and to take the necessary measures for preventing from the infections.

LIDERAZGO, LA COMPETENCIA ESENCIAL QUE TRANSFORMÓ UNA EMPRESA COLOMBIANA EN UN GIGANTE INTERNACIONAL: EL CASO DE CEMENTOS ARGOS

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HÉCTOR OCHOA DÍAZ

2011-01-01

Full Text Available Cementos Argos ha sido catalogado como uno de los gigantes de la industria cementera colombiana por su gran capacidad de consolidación en el mercado nacional y sus estrategias de internacionalización poco convencionales. Esta investigación documenta la experiencia internacional de Argos bajo la perspectiva de las teorías de internacionalización de mayor aceptación en laliteratura internacional, haciendo uso del enfoque metodológico de los estudios de caso. Como resultado se encontró que las estrategias de fidelización,aunadas al rediseño organizacional resultado del liderazgo de la alta gerencia, han sido herramientas vitales para asegurar el crecimiento de la compañía en los mercados local y externo.

Resistencia química del hormigón. XXVII. Contribución al estudio del sistema: cemento P-550-ARI hidratado-agua desionizada

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Bermejo-Muñoz, M. Francisca

1987-03-01

ón del agua desionizada, y c las modificaciones estructurales experimentadas por los compuestos cristalinos del cemento hidratado de los lechos sometidos a la acción del agua desionizada.

Durabilidad de un suelo contaminado y tratado con cemento portland Durability of a contaminated soil treated with portland cement

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José W Jiménez Rojas

2008-01-01

Full Text Available Este trabajo tiene por objetivo la aplicación de la técnica de solidificación/estabilización de suelos contaminados, analizando específicamente el comportamiento físico del suelo a través de ensayos de durabilidad. El suelo fue contaminado en laboratorio con residuo oleoso y la aplicación de la técnica tuvo cómo agente de encapsulamiento el cemento Portland CP V-ARI. Los ensayos de durabilidad, realizados según la NBR 13554 (1996, tuvieron como objetivo estudiar el grado de desagregación y vulnerabilidad del material con diversas combinaciones de dosificaciones de cemento y residuo oleoso, así cómo estudiar la variación volumétrica de los mismos. A partir de los resultados es posible observar que cuanto mayor la cantidad de contaminante, mayor es la pérdida de masa. Sin embargo, cuánto mayor es la cantidad de cemento, menor es la pérdida de masa y menor la variación volumétrica.This work seeks the application of solidification/stabilization techniques to contaminated soils analyzing specifically de physical behavior of the soil through tests of durability. The soil was contaminated in laboratory with acidic oily sludge industrial residues and the application of that technique had an encapsulate agent, the Portland cement CP V-ARI. The tests were carried out according to NBR 13.554 (1996, and they aimed to study the level of degradation and the vulnerability of the material with several combinations of cement and acidic oily sludge as well as study their volumetric variations. Starting from the results, it is possible to observe that the larger the contamination the larger the mass loss; however the larger the amount of cement, the smaller the mass loss and the more stable the volumetric variation.

El empleo de carbones en lo industrio del cemento

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García Conde, José

1977-09-01

Full Text Available La actual carestía de la energía y la escasez prevista para la segunda mitad de la próxima década, pueden aconsejar el estudio detallado del problema con que habrá de tener que enfrentarse la industria del cemento que depende, en gran medida, de un consumo energético elevado.

Fortalezas y debilidades de los inventarios de cementos para su empleo en análisis de ciclo de vida (ACV

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Aguado, A.

2004-04-01

Full Text Available Life-Cycle Assessment (LCA has become a common and accepted tool for quantifying the environmental impact of products. It is frequently used in some industrial sectors but this is not the case for construction products like cement. Reliable LCA require the use of reliable Life- Cycle Inventories (LCI; this is an important point because in Spain reliable LCI are scarce. An analysis of available LCI of different European cements is presented in this paper. This analysis includes the strengths and weaknesses of such inventories.

El análisis del ciclo de vida (ACV de productos se ha convertido en una herramienta usual de cuantificación de aspectos medioambientales de los mismos. Esta técnica, está bastante extendida en productos industriales estándar, pero no tanto, en productos del sector de la construcción, como es el cemento. Por otro lado, para la realización de un ACV fiable es necesario contar con inventarios, asimismo fiables, lo cual adquiere gran importancia ya que en España no existen de forma sistemática. En este artículo se hace un análisis de los inventarios públicos a los que se ha tenido acceso, correspondientes a diferentes cementos del ámbito europeo, reflejándose las fortalezas y debilidades de los mismos.

Cemento-ossifying Fibroma Of Paranasal Sinus Presenting Acutely As Orbital Cellulitis.

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Khanna, Maneesh; Buddhavarapu, Shanker Rao; Hussain, Sheik Akbar; Amir, Emran

2009-01-01

Fibro-osseous lesions of the face and paranasal sinuses are relatively uncommon. These lesions have overlapping clinical, radiologic and pathologic features causing difficulty in diagnosis. Neoplastic fibro-osseous paranasal sinus lesions can be benign or malignant. The benign fibro-osseous lesions described are: ossifying fibroma (and its histologic variants) and fibrous dysplasia. The variants of ossifying fibroma differ in the nature of calcified material (i.e. cementum versus bone), in the location of the lesion (oral versus paranasal sinus or orbital), other morphologic variations (presence of psammomatoid concretions) and biologic behavior (aggressive versus stable). Presence of cementum or bone classifies the lesion as cementifying fibroma or ossifying fibroma respectively while lesions with mixture of both cementum and bone are called cemento-ossifying fibroma. We describe a case of a young adult male with cemento-ossifying fibroma of paranasal sinus presenting acutely as left orbital cellulitis with proptosis.

Liderazgo, la competencia esencial que transformó una empresa colombiana en un gigante internacional : el caso de Cementos Argos

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Héctor Ochoa Díaz, Ph.D.

2011-09-01

Full Text Available Cementos Argos ha sido catalogado como uno de los gigantes de la industria cementera colombiana por su gran capacidad de consolidación en el mercado nacional y sus estrategias de internacionalización poco convencionales. Esta investigación documenta la experiencia internacional de Argos bajo la perspectiva de las teorías de internacionalización de mayor aceptación en la literatura internacional, haciendo uso del enfoque metodológico de los estudios de caso. Como resultado se encontró que las estrategias de fidelización, aunadas al rediseño organizacional resultado del liderazgo de la alta gerencia, han sido herramientas vitales para asegurar el crecimiento de la compañía en los mercados local y externo.

Florid cemento-osseous dysplasia: a report of two cases seen at the university college hospital ibadan.

Science.gov (United States)

Lawal, A O; Adisa, A O; Lasisi, T J

2011-06-01

Florid cemento-osseous dysplasia (FCOD) is commonly seen in black women, but few cases have been reported in sub-Saharan Africa. This article presents two cases of FCOD seen at the University College Hospital Ibadan. Two women aged 70 and 60 years were initially diagnosed as chronic osteomyelitis but both were eventually diagnosed as florid cementoosseous dysplasia after radiological examination by orthopanthomogram. Diagnosis of florid cemento-osseous dysplasia is possible by clinical examination and the distinct radiological presentation, especially on orthopanthomogram and a biopsy may not be required.

Conmemoración del cincuenta aniversario del Instituto de la Construcción y del Cemento «Eduardo Torroja»

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Editorial, Equipo

1984-11-01

Full Text Available The fiftieth foundation anniversary of the Building and Cement Institute (Instituto de la Construcción y del Cemento 'Eduardo Torroja " has been celebrated. On this occasion, an exhibition of Eduardo Torroja's works has been opened with the collaboration of the Civil Engineers College. At the same time, Scientifíc and Technic working meetings on Building and Cement have been held on November 20th, 21st and 22nd. Some Spanish and foreign well-known specialists have participated. The meetings were divided in three fields of study devoted to Building Materials, Technology of Building and Standards, Quality and Cooperation. The closing session of these Commemorative Acts was presided by the Minister of Public Works and Town Planning who was accompanied by the Presidents of the Higher Council of Scientifíc Research, of the Iberoamerican Cooperation Institute and of the Instituto Eduardo Torroja, among some other personalities.Se ha conmemorado el Cincuenta Aniversario de la Fundación del Instituto de la Construcción y del Cemento 'Eduardo Torroja". Con tal motivo, en la sede del Instituto se inauguró una Exposición de Obras de Eduardo Torroja, en colaboración con el Colegio de Ingenieros de Caminos. Paralelamente, durante los días 20, 21 y 22 de noviembre se desarrollaron unas Jomadas Científico- Técnicas sobre la Construcción y el Cemento. En ellas participaron destacadas figuras nacionales y extranjeras en el ámbito de la construcción y sus materiales y se estructuraron en tres campos de estudio, dedicados a Materiales de Construcción, Tecnología de la Construcción y Normativa, Calidad y Cooperación. La sesión de clausura de estos Actos Conmemorativos estuvo presidida por el Excmo. Sr. Ministro de Obras Públicas v Urbanismo, a quien acompañaban los Presidentes del Consejo Superior de Investigaciones Científicas y del Instituto de Cooperación Iberoamericana y el Presidente del Consejo del Instituto Eduardo Torroja, entre otras

Procedimiento de estabilización de mercurio líquido mediante cemento polimérico de azufre, vía sulfuro de mercurio.

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López-Delgado, Aurora; López Gómez, Félix Antonio; Alguacil, Francisco José; Alonso Gámez, Manuel

2011-01-01

Procedimiento de estabilización de mercurio líquido mediante cemento polimérico de azufre, vía sulfuro de mercurio. Procedimiento para la estabilización de mercurio líquido mediante la obtención de cementos poliméricos de azufre que comprende: (a) transformación del mercurio líquido en sulfuro de mercurio (metacinabrio) mediante reacción química, en condiciones estequiométricas, entre el mercurio y el azufre elemental; y (b) obtención de cemento polimérico de azufre me...

Resistencia química del hormigón. V.-Acción del agua de mar: Influencia de la adición de escoria a un cemento portland resistente al yeso. Evolución de las resistencias mecánicas a flexotracción y del coeficiente de corrosión

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Gaspar-Tébar, Demetrio

1980-09-01

Full Text Available Not available

En el presente trabajo (segundo de otro amplio en el que se estudia la influencia que ejercen diversas adiciones a tres cementos portland, desde un punto de vista de su comportamiento químico-resistente, frente a la acción de distintos medios potencialmente agresivos y que será objeto de otras publicaciones se da cuenta de la evolución que experimenta la resistencia química por el método de Koch-Steinegger y de las variaciones de las resistencias mecánicas a flexotracción de las probetas de mortero (1:3 de 1 X 1 X 6 cm hechas con un cemento portland industrial resistente al yeso (cemento 2 <> P-450-Y y con las mezclas cemento 2/escoria granulada (vítrea = 85/15 - 65/35 - 40/60 y 30/70 (en peso, sumergidas en agua potable filtrada, unas series de 12 probetas, y en agua de mar artificial (ASTM D 1141-75, otras series análogas, durante 56-90-180 y 360 días, después de haberlas curado 24 horas en un recinto saturado de humedad y hasta 21 días bajo agua potable filtrada.

Aplicaciones prácticas de la espectroscopía de absorción infrarroja en el estudio de los crudos, del clínker y del cemento portland anhidro

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Vázquez, Tomás

1980-01-01

En la primera parte de este trabajo (*) se trató brevemente y de una manera fundamentalmente práctica el estudio por espectroscopía infrarroja de calizas, arcillas, clínker portland y sus fases constituyentes. En, el presente trabajo finalizará esta exposición con una visión general de algunas posibilidades que tiene la espectroscopía IR en el estudio del cemento portland anhidro, así como el estudio breve de puzolanas, escorias y cenizas volantes, como adiciones activas.

Significance of steel electrical resistance method in the evaluation of reinforcement corrosion in cementitious systems

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Krajci, L.

2004-06-01

Full Text Available The suitable detection system of steel reinforcement corrosion in concrete structures contributes to the reduction of their maintenance costs. Method of steel electrical resistance represents non-destructive monitoring of steel in cementitious systems. Specially prepared and arranged test specimen of steel as a corrosion sensor is embedded in mortar specimen. Verification tests of this method based on chloride corrosion of steel in mortars as well as its visual inspection are introduced. Significance of steel electrical resistance method lies in the expression of steel corrosion by these quantitative parameters: reduction of cross-section of steel, thickness of corroded layer and loss of weight of steel material. This method is an integral method that allows the indirect determination of mentioned corrosion characteristics. The comparison of verified method with gravimetric evaluation of steel corrosion gives a good correspondence. Test results on mortars with calcium chloride dosages between 0.5% and 4.0% by weight of cement prove high sensitiveness and reliability of steel electrical resistance method.

La utilización de un sistema de detección de la corrosión de las armaduras en estructuras de hormigón puede contribuir a la reducción de sus costes de mantenimiento. El método de la resistencia eléctrica del acero consiste en la monitorización no-destructiva realizada sobre el acero en sistemas cementantes. Dentro de la muestra de mortero se coloca el sistema de detección, especialmente preparado y fijado, actuando como un sensor de la corrosión. En este trabajo se presentan ensayos de verificación de este método, junto con inspecciones visuales, en morteros sometidos a corrosión de armaduras por efecto de los cloruros. La efectividad de este método de la resistencia eléctrica del acero se expresa, en la corrosión de armaduras, de acuerdo a los siguientes parámetros cuantitativos: reducción de la sección transversal del

Effect of carbon nanofiber addition in the mechanical properties and durability of cementitious materials

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Galao, O.

2012-09-01

Full Text Available This paper reports on recent work that is directed at studying the changes in the mechanical properties of Portland cement based mortars due to the addition of carbon nanofiber (CNF. Both flexural and compression strength has been determined and related to the CNF addition to the mix, to the curing time and to the porosity and density of the matrix. Also, corrosion of embedded steel rebars in CNF cement pastes exposed to carbonation and chloride attacks has been investigated. The increase in CNF addition implies higher corrosion intensity and higher levels of mechanical properties.En este artículo se han estudiado los cambios en las propiedades mecánicas de los morteros de cemento Portland debido a la adición de nanofibras de carbono (NFC. Se han determinado las resistencias a flexotracción y a compresión de los morteros en relación a la cantidad de NFC añadidas a la mezcla, al tiempo de curado y a la porosidad y densidad de los mismos. Además se han investigado los niveles de corrosión de barras de acero embebidas en pastas de cemento con NFC expuestos al ataque por carbonatación y por ingreso de cloruros. El aumento en el porcentaje de NFC añadido se traduce en un aumento la intensidad de corrosión registrada y una mejora de las propiedades mecánicas.

[Long-term follow-up of cemento-osseous dysplasia: a contralateral recurrence before radiotherapy].

Science.gov (United States)

Khonsari, R H; Corre, P; Bouguila, J; Piot, B

2011-02-01

Cemento-osseous dysplasia is a benign fibro-osseous lesion of the jaws. Its complications are very rare. A panoramic x-ray was made to complete the pre-radiotherapy oral assessment of a 71-year-old female patient presenting with lung adenocarcinoma. This revealed a periapical fibro-osseous lesion on tooth n° 46. She had presented with a similar lesion on tooth n° 36, 16 years before. This had been treated by extraction and alveolar curettage. No surgical treatment was suggested for this recurrence on tooth n° 46. The diagnosis of focal cemento-osseous dysplasia is usually made on radiological and clinical data. The risk for transition to a florid form is unknown. Exeresis surgery before radiotherapy is discussed. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

El envejecimiento de las pastas de cemento reforzadas con fibras de vidrio

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Sánchez Paradela, M. L.

1992-06-01

Full Text Available Cement pastes reinforced with glassfibre, popularly called GRC ("Glassfibre Reinforced Cements" are compound materials which have been widely used in the construction field for the last 30 years. Their good mechanical properties, lightness and resistance to corrosion and fire make them suitable in the process of replacing the fibrocements with asbestos base in numerous applications. For that reason, their use has been extended in recent years and they have mainly been used to manufacture panels for facades and interior decoration as well as, to a smaller extent, for plumbing installations, roofs, lost formwork and even for "fingers" at the airports (1, 2, 3, 4, 5. Nevertheless, it has been known for over 25 years that GRC suffer deterioration with the time which affects their mechanical properties and especially their tenacity; they become fragile and crack under small deformations. The research carried out to determine the causes of the phenomenon and look for possible solutions has been intense and it would be impossible to give more details here due to the lack of space. We will try, nevertheless, to summarize some more relevant aspects of the problem and the solutions that have reached the highest point of development so far.

Las pastas de cemento reforzadas con fibras de vidrio, denominadas popularmente GRC ("Glassfibre Reinforced Cements", son materiales compuestos que se utilizan ampliamente en el campo de la Construcción desde hace unos 30 años. Sus buenas propiedades mecánicas, ligereza y resistencia a la corrosión y al fuego les hacen idóneos en el proceso de sustitución de los fibrocementos de base amianto en numerosas aplicaciones. Por tal motivo, su empleo se ha extendido en los últimos años, utilizándose fundamentalmente para fabricar paneles de cierre de fachadas y decoración de interiores y en menor grado para tuberías, cubiertas, encofrados permanentes e incluso para "fingers" o brazos de acceso a los aviones

Ensayos de resistencia a la compresión de bloques de suelo cemento

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Mas, J. M.

2011-12-01

Full Text Available The purpose of this study is to determine the proper dosage for a particular type of soil, which will be used to make soil-cement blocks to build a home in El Puestito, Burruyacu, Tucumán, Argentina. Two soil samples were extracted from studied area and samples of soil-cement specimens, using a mixture of two samples simultaneously and with each one separately. Another variable introduced was the pressure of production. At 28 days, were tested in two ways: first, subjecting them to compression at break and the second tests was made by submerging them in water and weighing them at certain time intervals. The results showed that: increasing the pressure of production, increases resistance to compression, while the absorption decreases. The results also showed that greater amounts of soil 1, enhances the resistance to breakage.

El objetivo de este trabajo es determinar la dosificación más adecuada para un determinado tipo de suelo, que se utilizará para fabricar bloques de suelo-cemento, para construir una vivienda en El Puestito, Burruyacu, Tucumán, Argentina. Se extrajeron dos muestras de suelo del área estudiada y se fabricaron probetas de suelo-cemento, utilizando la mezcla de dos muestras a la vez y con cada una por separado. Otra variable introducida fue la presión de fabricación. A los 28 días, fueron ensayadas de dos maneras: la primera, sometiéndolas a la compresión hasta la rotura y la segunda, sumergiéndolas en agua, pesándolas en intervalos de tiempos determinados. Los resultados mostraron que: aumentando la presión de fabricación, se aumenta la resistencia a la compresión, mientras que la absorción disminuye. Las dosificaciones con mayor cantidad de suelo 1 con respecto a la de suelo 2, producen un aumento de la resistencia a la rotura.

Florid cemento-osseous dysplasia (FCOD: case report

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Tai-Min Lin

2010-12-01

Full Text Available Florid cemento-osseous dysplasia (FCOD is a type of fibro-osseous lesion and represents a reactive process in which normal bone is replaced by poorly cellularized cementum-like materials and cellular fibrous connective tissues. It is strictly localized to the tooth-bearing or edentulous areas, often occurring bilaterally with symmetric involvements. In this case report, a mixed radiolucent and radiopaque lesion at the periapical area of the right mandibular second molar of a 46-year-old female patient was misdiagnosed as chronic apical periodontitis initially by clinical manifestation and radiographic finding on a periapical radiograph. The tooth #47 was a distal abutment tooth of a three-unit bridge from teeth #45–#47. No decay of teeth #45 and #47 was found when the bridge was removed. Electric pulp test revealed that the tooth #47 was a vital-pulp tooth. Panoramic radiography showed a similar mixed radiolucent and radiopaque lesion at the edentulous area of tooth #37. The symmetric distribution of the two lesions with no alveolar bone expansion and the positive vitality test of the involved tooth supported the diagnosis of FCOD for this case. No endodontic treatment or surgical biopsy was performed. The patient was instructed to undergo regular clinical and radiographic follow-up to monitor the change of the lesion. We suggest that when a radiolucent or mixed lesion occurs at the periapical area of a vital-pulp tooth, panoramic radiography may help differentiate an inflammatory periapical lesion from a lesion of cemento-osseous dysplasia (COD.

Aplicaciones prácticas de la espectroscopía de absorción infrarroja en el estudio de los crudos, del clínker y del cemento portland anhidro

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Vázquez, Tomás

1980-09-01

Full Text Available Not available

En la primera parte de este trabajo (* se trató brevemente y de una manera fundamentalmente práctica el estudio por espectroscopía infrarroja de calizas, arcillas, clínker portland y sus fases constituyentes. En, el presente trabajo finalizará esta exposición con una visión general de algunas posibilidades que tiene la espectroscopía IR en el estudio del cemento portland anhidro, así como el estudio breve de puzolanas, escorias y cenizas volantes, como adiciones activas.

Residuos cerámicos para su posible uso como materia prima en la fabricación de clínker de cemento Portland: caracterización y activación alcalina

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Martínez-Ramírez, S.

2006-03-01

Kioto. El empleo de diferentes residuos y subproductos industriales como materiales alternativos en la fabricación de cemento se ha revelado como un medio muy efectivo para alcanzar, en gran parte, esa sostenibilidad. Estos materiales alternativos pueden ser incorporados en el proceso de fabricación de cemento, por la sustitución parcial de los combustibles convencionales y/o de las materias primas del crudo y por la incorporación de adiciones activas al cemento y/o clínker.En el presente trabajo se exponen los resultados preliminares obtenidos al estudiar la composición y activación alcalina de seis residuos cerámicos cocidos con vistas a su viabilidad de sustituir, parcialmente, algunas materias primas, utilizadas en la preparación de un crudo de cemento.Los resultados obtenidos han mostrado que los seis residuos tienen una composición química y mineralógica adecuada para su posible empleo como materia prima alternativa de un crudo de cemento Portland. No son ni tóxicos ni radioactivos. Como era de esperar estos residuos tienen capacidad puzolánica. A la edad de estudio (8 días la activación alcalina de los residuos es baja. El contenido en fase amorfa y la naturaleza del activador no parecen ser factores que influyan en dicho proceso de activación. El estudio de caracterización realizado sobre las pastas activadas ha demostrado que las fases feldespáticas son las más susceptibles de disolución y reacción con las disoluciones alcalinas.

The prevalence, clinical and radiographic characteristics of cemento-osseous dysplasia in Korea

International Nuclear Information System (INIS)

Cho, Bong Hae; Jung, Yun Hoa; Nah, Kyung Soo

2007-01-01

This study was intended to estimate the prevalence of cemento-osseous dysplasia (COD) in the Korean population and to assess the clinical and radiographic characteristics of this condition. Panoramic radiographs from 10,646 patients (4.982 males and 5.664 females, age range from 6 to 91 years) were reviewed for evidence of COD. Their demographics, clinical characteristics, and radiographic features were retrospectively assessed. Of 10,646 panoramic radiographs, 33 radiographs (0.31%) exhibited evidence of COD. The prevalence of COD increased to over 1% in women over 40-years old. Of these 33 patients, 16 had florid cemento-osseous dysplasia (FCOD) and 17 had focal COD. Due tp the multiplicity of FOCD, a total of 63 COD lesions were assessed. These lesions were most common in the mandibular molar area. Most of the COD lesion examined (61.9%) were less than 10 mm and the majority (82.5%) showed radiopacity. COD has a predilection for the mandibular molar area of middle-aged and older women

The prevalence, clinical and radiographic characteristics of cemento-osseous dysplasia in Korea

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Cho, Bong Hae; Jung, Yun Hoa; Nah, Kyung Soo [Pusan National Univ. College of Dentistry, Pusan (Korea, Republic of)

2007-12-15

This study was intended to estimate the prevalence of cemento-osseous dysplasia (COD) in the Korean population and to assess the clinical and radiographic characteristics of this condition. Panoramic radiographs from 10,646 patients (4.982 males and 5.664 females, age range from 6 to 91 years) were reviewed for evidence of COD. Their demographics, clinical characteristics, and radiographic features were retrospectively assessed. Of 10,646 panoramic radiographs, 33 radiographs (0.31%) exhibited evidence of COD. The prevalence of COD increased to over 1% in women over 40-years old. Of these 33 patients, 16 had florid cemento-osseous dysplasia (FCOD) and 17 had focal COD. Due tp the multiplicity of FOCD, a total of 63 COD lesions were assessed. These lesions were most common in the mandibular molar area. Most of the COD lesion examined (61.9%) were less than 10 mm and the majority (82.5%) showed radiopacity. COD has a predilection for the mandibular molar area of middle-aged and older women.

Un método numérico-estadístico para determinar el volumen elemental representativo (VER) de la pasta de cemento en la medición de la difusividad

OpenAIRE

Zhang, M. Z.; Ye, G.; van Breugel, K.

2010-01-01

La difusividad del hormigón depende de su microestructura a numerosas escalas, desde nanómetros hasta milímetros, por lo que se precisa de técnicas multiescala para representar este parámetro. Junto con el principio de homogeneización, uno de los métodos multiescala más habituales es el volumen elemental representativo (VER). El objeto de este estudio era establecer un procedimiento que permitiera determinar el VER necesario para calcular la difusividad de la pasta de cemento, basándose en un...

Estudio de un cemento de las ruinas de Teotihuacan

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Goldschimdt, A.

1981-06-01

Full Text Available Not available

Se estudió un mortero de cemento portland de aproximadamente 30 años expuesto a la intemperie y otro mortero de las ruinas de Teotihuacan, mediante Microsonda (EM y Microscopía Electrónica de Barrido (SEM. Mostrándose la diferencia entre ambos morteros y evidenciando la semejanza, del de Teotihuacan -cuya edad es anterior a la conquista del Imperio Azteca- con el mortero puzolánico Romano.

Approach to the effect of concrete resistivity in the corrosion of rebars in concrete

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Andrade, C.

1987-09-01

Full Text Available The concrete resistivity has been considered as a factor which affects the corrosion rate of the rebars. Untill now the only relation found has been stablished between potentials and resistivity for steel embedded in Chloride contaminated concrete. In this paper a comparison between corrosion rate of rebars, determined from Polarization Resistance method, and Electrical Resistance data measured through the electronic compensation of the ohmic drop are given. The results of i_corr and R_ohm has been measured for rebars embedded in mortar made with three different types of cement. The specimens were submited to an accelerated carbonation. The relation between i_corr and R_ohm is quite similar in all the cases and suggests that the concrete electrical resistivity may be a controling factor of the corrosion rate of the rebars.

La resistividad del hormigón se ha venido considerando como uno de los factores que afectan a la velocidad de corrosión de las armaduras, aunque, hasta ahora, la única relación encontrada ha sido la establecida entre los potenciales y la resistividad para acero embebido en hormigón contaminado por cloruros. En este trabajo se establecen comparaciones entre velocidad de corrosión de las armaduras, medida a través del método de determinación de la Resistencia de Polarización, y los datos de resistencia eléctrica medidos a través de la compensación de caída óhmica. Los resultados de i_corr y R_ohm se han medido en armaduras embebidas en mortero fabricado con tres tipos de cemento a los que se ha sometido a un proceso de carbonatación acelerada. La relación entre i_corr y R_ohm es muy similar en todos los casos y sugiere que la resistencia del hormigón puede actuar como un factor controlante de la velocidad de corrosión de las armaduras.

Influencia de la aireación de clínkeres y cementos sobre sus propiedades físicas y mecánicas

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Venuat, M.

1959-08-01

Full Text Available Not availableEl autor señala, en primer término, los ensayos a realizar sobre las principales características del cemento, en particular sobre tiempo de fraguado, resistencias mecánicas y tiempos de fisuración en anillos de pasta pura. La base para la redacción de este trabajo partió de las divergencias observadas en los tiempos de fisuración en el anillo de pasta pura, unido a una propuesta de los fabricantes para conocer la influencia del envejecimiento del clínker sobre las propiedades del cemento; a continuación se estudiaron las características principales del cemento en función de su aireación.

The effect of corrosion on stained glass windows

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Laissner, Johanna

1996-06-01

Full Text Available Stained glass windows belong to the most important cultural heritage of Europe. Within the last decades a disastrous deterioration took place. The wonderful stained glass windows and their glass paintings as pieces of art are acutely menaced by environmental corrosive influences. This corrosion process is a very complex reaction which is not only influenced by temperature and humidity changes but also by gaseous pollutants like sulfur dioxide, nitrogen oxides or ozone, by dust and air, microorganisms as well as synergetic interactions. Strongly affected by these environmental attacks are medieval stained glasses due to their chemical composition. They have a low content in silica and high contents of modifier ions (e.g. potassium and calcium. The corrosion phenomena can range from predominantly pitting on the surface to the formation of thick corrosion crusts which are turning the panel opaque and thus reducing strongly the transparency of the windows. In order to set up a conservation and restoration concept, it is necessary to know about the environmental conditions to which the stained glass windows are exposed. For this purpose very corrosion sensitive model glasses (so called glass sensors were developed which have a similar chemical composition as historic stained glasses. They exhibit the same corrosion reactions but react much faster, and are now widely used to estimate corrosive stresses on stained glass windows to give basic information about the corrosive impacts which work on the historic glasses. In this paper principle corrosion mechanisms of stained glass windows and their enhancing factors are discussed. For the evaluation of the environmental impact, the application of glass sensors is demonstrated.

Las vidrieras coloreadas pertenecen al legado cultural más importante de Europa. En las últimas décadas se ha producido en ellas un desastroso deterioro. Las maravillosas vidrieras coloreadas y sus policromías est

Resistencia a la corrosión ácida de morteros de cementos adicionados con catalizador de craqueo catalítico gastado (sFCC

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Silvia Izquierdo

Full Text Available El catalizador de craqueo catalítico gastado (sFCC es un residuo producido por la industria petroquímica y ha demostrado una elevada potencialidad como adición puzolánica en mezclas de cemento Portland (OPC. El presente artículo evalúa la eficacia del sFCC como adición mineral activa en morteros de cemento Portland, así como la resistencia al ataque químico cuando los materiales producidos son inmersos en ácido sulfúrico (H2SO4, acético (CH3COOH o clorhídrico (HCl. Se llevó a cabo una comparación del desempeño del sFCC como adición frente a adiciones comercialmente disponibles, tales como humo de sílice (SF y metacaolín (MK. Los resultados revelan un incremento en las resistencias mecánicas de hasta un 17% en morteros con sFCC en comparación a un mortero referencia sin adición (OPC. La inmersión en H2SO4 durante 90 días condujo a la formación de yeso y pérdida de resistencias mecánicas de hasta un ~25% en las mezclas con MK y sFCC. Para las muestras inmersas en HCl y especialmente las constituidas con sFCC y MK, se identificó Sal de Friedel, como consecuencia del ingreso de Cl" y posterior reacción con los monosulfoaluminatos formados durante la hidratación del cemento. La inmersión en ácido acético condujo a pérdidas de resistencia de hasta un 57% para OPC y 37% para morteros adicionados con sFCC. De esta manera, la inmersión en HCl promueve el mayor ataque para los sistemas adicionados y posterior deterioro, seguido del CH3COOH y H2SO4. Se destaca el mejor desempeño del mortero con 20% sFCC, en particular en presencia de ácido sulfúrico.

Comparación de las propiedades del concreto utilizando escoria de alto horno como reemplazo parcial y total del cemento Pórtland ordinario

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I. Escalante

2008-06-01

Full Text Available Se realizó una investigación con dos tipos de concreto siguiendo la norma ACI 211.1: a concretos sustituidos al 30, 50 y 70 % con escoria de alto horno (EAH y b concretos 100 % EAH activada con 4, 6 y 8 % de óxido de sodio (Na2O en forma de silicato de sodio de módulo 2.0. Todos los sistemas se caracterizaron mecánicamente de 1 a 28 días. Se utilizó microscopía electrónica de barrido y espectroscopía por dispersión de energía para analizar la microestructura, grado de avance de la reacción y productos formados. La sustitución parcial del cemento Pórtland (CPO por EAH no fue benéfica para las propiedades mecánicas, contrario a la sustitución total por EAH activada, la cual resultó en propiedades mecánicas superiores que las de concretos de puro CPO. La activación de la escoria con 8 % de Na2O resultó más efectiva, seguido de 6 y 4 % de Na2O.

Contribución al estudio de la sacarosa como aditivo retardador de la hidratación del cemento

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Sotolongo, R.

1993-06-01

Full Text Available It is evaluated the influence of the saccharose as a retarder additive of the cement set in the hydration of the alita and the development of the mechanical proprieties of Portland cement pastes till the age of 70 days. The study has had in consideration additions of saccharose of o to 0.400 % / cement weight, also the influence of the fineness of the conglomerate and the use of the retarder mixed with an additive superplastic and an active mineral (natural puzolana.

Se evalúa la influencia de la sacarosa como aditivo retardador del fraguado del cemento en la hidratacion de la alita y el desarrollo de las propiedades mecánicas de pastas de cemento portland hasta la edad de 90 días. El estudio contempló adiciones de sacarosa de 0 a 0,400% /peso del cemento, así como la influencia de la finura del conglomerante y el uso del retardador mezclado con un aditivo superplastificante y un mineral activo (puzolana natural.

Florid cemento osseous dysplasia in association with dentigerous cyst.

Science.gov (United States)

Sanjai, Karpagaselvi; Kumarswamy, Jayalakshmi; Kumar, Vinod K; Patil, Archana

2010-07-01

We present a case of florid cemento-osseous dysplasia occurring in a 20-year-old Indian woman. The subject presented with three lesions involving the maxillary right quadrant, maxillary left quadrant and mandibular left quadrant. The mandibular left quadrant also demonstrated a cyst.The diagnosis was made by correlating the clinical presentation with that of the radiological and histopathological findings. This is a rare entity because of an unusual combination of Asian race along with the association of dentigerous cyst.

Florid cemento-osseous dysplasia: a report of two cases seen at The ...

African Journals Online (AJOL)

Florid cemento-osseous dysplasia (FCOD) is commonly seen in black women, but few cases have been reported in sub-Saharan Africa. This article presents two cases of FCOD seen at the University College Hospital Ibadan. Two women aged 70 and 60 years were initially diagnosed as chronic osteomyelitis but both were ...

Reuse of a residue from petrochemical industry with portland cement Reutilización de un residuo de la industria petroquímica como adición al cemento portland

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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

Puesta al día de la colaboración científico-técnica española del I.E.T.C.C. con Iberoamérica en el campo del cemento y del hormigón

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Calleja, José

1981-03-01

Full Text Available Not available

Se trata de actualizar la exposición de la labor llevada a cabo durante los años 1978 a 1980 por el autor de este trabajo en Brasil y en Argentina, a invitación personal de entidades oficiales de ambos países relacionadas con los campos de la docencia, de la ingeniería, dela construcción y de sus materiales. Labor consistente en el desarrollo de cursos, conferencias, coloquios y mesas redondas sobre temas relativos a la tecnología y a la durabilidad del cemento y del hormigón, y al empleo racional de los cementos en los diferentes tipos de obras, como solución a los problemas que el hormigón puede presentar en ellas. Dicha labor se presenta en forma resumida, sin perjuicio de que una buena parte de ella se ofrezca desarrollada in extenso en otras publicaciones técnicas.

Peripheral cemento-ossifying fibroma: Report of a recurrence case.

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Sah, Kunal; Kale, Alka D; Hallikerimath, Seema; Chandra, Sunira

2012-04-01

Peripheral cemento-ossifying fibroma [PCOF] is a reactive gingival overgrowth occurring frequently in the maxillary anterior region in teenagers and young adults. Here, we report a case of POCF in a 13-year-old male, which was previously surgically excised and had recurred after a period of 9 months. PCOF should be considered in differential diagnosis of such reactive hyperplastic lesions originating from the gingiva. Hence, early diagnosis with proper surgical excision and aggressive curettage of the adjacent tissues are essential for prevention of recurrence.

Plan estratégico para Cemento Pacasmayo S.A.

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Mayorca Castillo, Carolina; Miranda Mendoza, Alberto; Solano Arroyo, Luis Enrique; Tuesta Aguilar, Manuel Antonio

2016-01-01

xii, 119 h. : il. ; 30 cm Este documento constituye un planeamiento estratégico para la empresa Cementos Pascamayo, cubriendo el período 2016-2030. Se proyecta que al finalizar este plazo la empresa estará entre las tres primeras de América Latina, cubriendo el Perú y con presencia en otros países de la región. Para ello deberá ampliar su infraestructura, realizar aventuras conjuntas en mercados extranjeros y desarrollar nuevos productos, entre otros. Los objetivos de largo ...

Focal cemento-osseous dysplasia masquerading as benign cementoblastoma: A diagnostic dilemma.

Science.gov (United States)

Rao, Gayathri S; Kamalapur, Muralidhar G; Acharya, Swetha

2014-01-01

Focal cemento-osseous dysplasia (FCOD) is a fibro-osseous lesion that is a nonneoplastic reactive lesion. A case of 47-year-old female patient presenting with a diagnostic dilemma to the clinician is reported. Methods to achieve definitive diagnosis are discussed. FCOD can present with features of periapical pathology or other osseous lesions. Hence, to arrive at a definitive diagnosis biopsy and histopathologic examination is imperative.

Resistencia química del hormigón. XXIII. Influencia de la adición de escoria a un cemento portland resistente al yeso. Estudio de la concentración iónica del sistema cemento 2/escoria-agua potable filtrada

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Sagrera-Moreno, José Luis

1984-06-01

Ca (II y SO₄ (II de los medios (agua potable filtrada en donde han estado sumergidas las probetas de mortero (1: 3 hechas con un cemento portland industrial resistente al yeso (cemento 2 <> P-450-Y y con las mezclas cemento 2/escoria - 85/15 - 65/35 - 40/60 y 30/70, en peso, durante el período de curado (21 días y, posteriormente, durante 56 - 90 - 180 y 360 días (períodos de conservación, en esta etapa. Así mismo, se estudia la composición química de las nuevas fases sólidas formadas en dichos medios; la composición estructural de dichas fases sólidas se determinó por DRX (calcita, en ambos periodos y, además, aragonito durante el período de conservación de las series de probetas hechas sólo con cemento 2, de ello se dio cuenta en (2. En este sistema cemento 2/escoria-agua potable filtrada se ha puesto de manifiesto que se produce un incremento del contenido de Ca (II en la disolución y en las mencionadas fases sólidas, así como del valor del pH, que dependen de la mezcla utilizada para fabricar las diversas series de probetas y del tiempo de conservación. Las cantidades de Ca (II que se encuentran en las distintas soluciones (agua potable filtrada son, normalmente, menores de 0,1 X 10^-2 moles, mientras que en las nuevas fases sólidas son superiores a dicha cantidad y, por regla general, a 0,5 X 10^-2moles. El ion SO₄ (II no se ha detectado en las nuevas fases sólidas, habiéndose encontrado en pequeñas cantidades en las distintas fases líquidas (agua potable filtrada. El contenido de dichos iones es, normalmente, del mismo orden que el del agua potable filtrada en los medios en donde han estado sumergidas las diversas series de probetas, excepto en aquellos medios en donde han estado las probetas que tienen los mayores contenidos de escoria (60 y 70%, en peso.

Pericoronal occurrence of cemento-ossifying fibroma: an unexemplified and unusual case report with review of literature.

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K L, Kumaraswamy; R S, Arvind Babu; P, Sheshadri; Kumaran, Santhosh

2014-03-01

The Cemento-ossifying fibroma (COF) is an odontogenic neoplasm that is predominantly considered as a fibro osseous lesion of the jaw bone. The histogenetic origin of COF was thought to be derived from the periodontal cells, which have the ability to form fibrous, cementum and osseous tissue. Due to the periodontal cellular origin, the lesion often occurs in the radicular portion of the bicuspid and molar tooth region of the lower jaw. We present a case of Cemento-ossifying fibroma in a 43-year-old female in the pericoronal aspect of an impacted third molar mimicking an odontogenic lesion. The occurrence of COF in pericoronal region is an unusual site. This article also discusses about the various hamartomatous lesions occurring in the pericoronal region of the teeth.

Juvenile aggressive cemento-ossifying fibroma of the sphenoid sinus with proptosis: a surgical dilemma.

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Singh, Rohit; Ramaswamy, Balakrishnan; Hazarika, Manali

2013-11-27

The term fibro-osseous lesion has currently grown in popularity as an overall designation for a number of rare, histologically benign head and neck lesions that are made up of bone, fibrous tissue and cementum. Cemento-ossifying fibroma is a variant of cementifying fibroma and is a fibro-osseous disease. They are usually small innocuous lesions which follow a slow benign course and are commonly seen in the skull bone rather than the sphenoid. It is rare for these tumours to attain large size, behave aggressively, destroy bone and require a radical surgery. One such rapidly growing juvenile cemento-ossifying lesion of sphenoid in our 10-year-old young patient causing proptosis and impaired vision is reported here because of its uncommon nature and its surgical dilemma. Selection of surgical approach to resect this tumour becomes difficult because it is deeply seated and needs a multidisciplinary approach.

Florid cemento-osseous dysplasia: report of two cases and review of the literature

International Nuclear Information System (INIS)

Melo, Alessandro Severo Alves de; Torres, Erika Esteves Araujo; Keppke, Ana Luiza Leitao; Vianna, Alberto Domingues; Mello, Walter de Assis; Marchiori, Edson

1998-01-01

The present paper describes two cases of floride cemento-osseous dysplasia in black women. The radiographs showed sclerotic lesion in the mandible, in both cases, and in the maxilla, in one case. After resection of the lesions the evolutions were favorable. The authors show radiologic characteristics and review the literature. (author)

Effect of steel surface conditions on reinforcing steel corrosion in concrete exposed to marine environments

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Anzola, E.

2005-09-01

Full Text Available Laboratory methods and experimental tests were deployed in the present study to evaluate corrosion in reinforced concrete exposed to marine environments. Reinforcing steel exhibiting two different surface conditions prior to embedment in concrete were studied, one the one hand to assess the electrochemical behaviour of the bars during exposure of the concrete specimens to a simulated marine environment, and on the other to determine the strength of the steel/concrete bond. The reinforced concrete specimens prepared were adapted as required for electrochemical potential and corrosion rate testing. A total of 56 7x15-cm cylindrical specimens containing 3/8" steel rods anchored at a depth of 11.5 cm were made to evaluate the steel / concrete bond and exposed to a natural marine environment for 28 or 190 days prior to testing. All the specimens were made with ready-mixed concrete. It may be concluded from the results of the corrosion tests on reinforcing steel with different surface conditions that the oxide initially covering the bars was dissolved and the steel passivated by the alkalinity in the concrete. The chief finding of the bonding study was that the layer of oxide formed in pre-embedment steel deterioration contributed to establishing a better bond.

En el contexto de esta investigación, se tomaron en consideración métodos y ensayos experimentales de laboratorio, que permiten hacer una evaluación de la corrosión del hormigón armado expuesto en ambientes marinos. Por una parte se evaluó el comportamiento electroquímico de dos condiciones de estados superficiales del acero embebido en el hormigón, exponiéndolo en un ambiente marino simulado y, por otra parte, se estudió la adherencia entre el acero y el hormigón, con los mismos estados superficiales usados para la evaluación electroquímica. Las probetas se fabricaron de hormigón con acero de refuerzo en su interior, adecuándolas para realizar los ensayos de potenciales

Valorización de Cementos Pacasmayo S.A.A.

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Briceño Montalván, Juan Manuel; Joseli Ortiz, William; Linares Céspedes, Gustavo Adolfo

2017-01-01

El trabajo de investigación tiene como finalidad realizar la valorización de la empresa Cementos Pacasmayo basándose en el análisis de la situación financiera de la empresa, los supuestos que se proponen acerca de las expectativas futuras de la empresa (expectativas de crecimiento, flujos futuros, etc.) y los conocimientos adquiridos durante nuestros años de estudio. En el Capítulo I se describe la industria cementera, se analiza su desempeño y las características de los actores productivos, ...

Normalización del cemento. Características químicas: Algunos comentarios sobre los métodos de ensayo

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Gaspar-Tebar, Demetrio

1978-12-01

Full Text Available El Pliego de Prescripciones Técnicas Generales para la Recepción de Cementos (RC-75, Decreto 1.064/1975 de 23 de mayo de 1975, publicado en los B.O.E. núms. 206 y 207, de fechas 28 y 29 de agosto, respectivamente, del mismo año, incluye la clasificación de los cementos, las prescripciones relativas a las características químicas y físicas, así como los métodos de ensayo que se deben utilizar para determinar dichas características.

Cenizas, cementos y hormigones con cenizas

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Calleja, José

1982-09-01

Full Text Available This paper describes the chemical composition and the morfological nature of pulverized coal ashes, as well as their physical characteristics. Their influences —actions and effects— on the main properties and behaviour of cements and concretes, and the more adequate conditions for their efficient use un them are also described.

En este trabajo se exponen la composición química y la naturaleza morfológica de las cenizas pulverulentas de los carbones, así como sus características físicas. Se describen asimismo sus influencias —acciones y efectos— sobre las principales propiedades y comportamientos más importantes de los cementos y de los hormigones, así como las condiciones más idóneas para su más eficaz empleo con y en ellos.

Detection of the cemento-enamel junction with three different probes: an "in vitro" model

NARCIS (Netherlands)

Barendregt, D.S.; van der Velden, U.; Timmerman, M.F.; Bulthuis, H.M.; van der Weijden, G.A.

2008-01-01

Aim: The purpose of the present study was to test the accuracy and precision with which the cemento-enamel junction (CEJ) can be assessed using three commercially available periodontal probes with different tip endings in both deciduous and permanent teeth. Material and Methods: An "in vitro" model

Case Presentation of Concomitant and Contiguous Adenomatoid Odontogenic Tumor and Focal Cemento-Ossifying Dysplasia.

Science.gov (United States)

Rezvani, Gita; Donoghue, Mandana; Reichart, Peter A; Pazuhi, Neda

2015-01-01

A 24 year-old male was presented for the diagnosis of an asymptomatic bony expansion in relation to the right maxillary canine and first premolar. The unilocular radiolucent lesion with central foci of calcification had caused divergence of canine and first premolar roots without any resorption. This case report details a diagnosis of two distinct disease processes of different cellular origin namely, focal cemento-ossifying dysplasia and adenomatoid odontogenic tumor in a previously unreported concomitant and contiguous relationship. The diagnosis was determined by a combination of clinical, radiographic, histopathological and surgical evidence. This case highlights two points, first the need to examine all mixed radiolucent-radiopaque lesions with advanced imaging techniques to assess the number and extent of the lesions prior to treatment planning. Second a likely role of periodontal ligament as the tissue source for odontogenic epithelial cells and mesenchymal stem cells required for the development of odontogenic tumors and cemento-osseous dysplasias.

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

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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.

El empleo de la grava-cemento en los firmes de carretera

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Llamazares Gómez, Olegario

1971-06-01

Full Text Available Layers of gravel-cement have been used for several years in road surfacing replacing the granular bases at the stretches where traffic makes high-strength structural sections necessary. Experience has brought about the evolution of this technique so as to obtain higher quality layers of greater guarantee with a more careful selection of the aggregates with respect to granulometry and form, batching and cement type and manufacturing conditions, implementation and curing. This article reports on the current tendences for the above points, indicating the requirements of contract specifications.Capas de grava-cemento se emplean, desde hace varios años, en los firmes de carretera, sustituyendo a las bases granulares en los tramos en que el tráfico requiere secciones estructurales de elevada resistencia. La experiencia ha aconsejado la evolución de esta técnica para llegar a capas de mayor calidad y garantía, con una selección más cuidada de los áridos en granulometría y forma, dosificaciones y tipo de cemento y condiciones de fabricación, puesta en obra y curado. En el presente artículo se informa sobre las actuales tendencias en todos estos puntos, indicando las exigencias de los Pliegos contractuales.

Estudio del uso del lodo residual de la empresa Extralum S. A. como material alternativo en la fabricación de cementos especiales

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Maricruz Vargas Camareno

2006-05-01

Full Text Available La empresa Extralum S. A. es una industria dedicada a la manufactura de aluminio crudo, anodizado y laqueado para uso arquitectónico. En su proceso de tratamiento de aguas residuales, genera alrededor de 90 toneladas al mes de un sólido blanco, el cual ya ha sido caracterizado, y se encontró que es rico en óxidos de aluminio hidratados; en la actualidad este material es desechado en rellenos sanitarios. Considerando que el cemento es un producto con demanda creciente, que para su producción requiere altos consumos de energía, cualquier avance que se realice para disminuir el consumo energético,tiene importantes beneficios económicos y ambientales. Dentro de las soluciones posibles, se encuentra la utilización de materiales alternativos que pueden ser utilizados como materias primas o materiales cementosos de reemplazo parcial o total del cemento Pórtland. Las pruebas realizadas a las diferentes mezclas demuestran que el lodo incorporado al cemento como relleno, modifica sus características iniciales, acelerando los tiempos de fragua, aumentando la porosidad del material, condición que afectó, negativamente, la resistencia del cemento, pero aumentó su capacidad aislante.

Empleo de combustibles alternativos en la fabricación de cemento. Efecto en las características y propiedades de los clínkeres y cementos

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Puertas, F.; Blanco-Varela, M. T.

2004-01-01

[ES] Se han estudiado clínkeres y cementos obtenidos en procesos industriales que han utilizado combustibles convencionales y combustibles alternativos (harinas cárnicas, neumáticos usados y mezclas de ambos). Los resultados obtenidos han demostrado que los clínkeres fabricados con los combustibles alternativos no presentan diferencias significativas en la composición mineralógica respecto a los obtenidos con combustibles convencionales. Los contenidos de metales pesados en los clínkeres proc...

Investigación, desarrollo e innovación de compósitos de fibras naturales aglutinados con cemento portland ordinario.

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Macías Almazán, Aarón

2015-01-01

El presente trabajo se basa en la elaboración de tableros aglomerados con mayor o menor proporción de mezcla cemento:bagazo de caña de azucar, utilizando tratamientos de molienda para disminuir y homogenizar el tamaño de partícula, disminución de extractos y azúcares para el bagazo, así como dos diferentes tratamientos de mineralización superficial para la fibra para mejorar su compatibilidad con la matriz de cemento, uno con Ca(OH)2 y otro con Na2SiO3. Se elaboraron probeta...

Diferencias y similitudes entre morteros de cal hidráulica y morteros mixtos de cal área y cemento portland

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Peñaranda García, Pilar

2012-01-01

En el presente trabajo se estudian el mortero de cal hidráulica y el mortero mixto de cal aérea y cemento Portland, siendo este último el más utilizado en la actualidad, ya que la cal ha pasado a un segundo plano en la construcción debido a los grandes avances en la producción de cemento a lo largo del siglo XX. Estos avances han desplazado a la cal, un material utilizado desde hace milenios, olvidando su alta resistencia al paso del tiempo, cuya prueba es el gran volumen de ...

Resistencia química del hormigón. XXIV. Influencia de la adición de escoria a un cemento portland resistente al yeso. Estudio de la concentración iónica del sistema cemento 2/escoria-agua de mar artificial

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Gaspar-Tébar, Demetrio

1984-12-01

, the Ca (II content in the ASTM artificial sea-water is taken into account, the dissolving process of the Ca (II compounds in the cement (average values may be added. The Mg (II ion has virtually disappeared from the ASTM artificial sea-water, in which were submerged the series of mortar samples made up of cement 2 and of the mixture containing 15% slag, in weight; in these environments, it has precipitated in the form of brucite. In the other environments, it is found in various quantities, according to the mixture used in making up the samples. The greatest quantities of SO₄ (II and Cl (I ions that have disappeared from the artificial sea-water correspond to the environments containing the mortar samples made up of cement 2 and the mixtures with 15% and 35% slag for the first, and 35%, 60% and 70% slag in the case of the second. In the new solid stages, SO₄ (II ions have been detected in quantities of less than 0.07 X 10^-2 moles.

En el presente trabajo, continuación de otros, se estudia la evolución de la cantidad de fase sólida formada en el agua de mar artificial ASTM D 1141-75 en donde han estado sumergidas las series de probetas (1:3 hechas con un cemento portland resistente al yeso (cemento 2< > P 450-Y y con las mezclas cemento 2/escoria = 85/15, 65/35, 40/60 y 30/70, en peso, durante 56-90-180 y 360 días (períodos de conservación-ataque, en esta etapa, después del período de curado (1 día en cámara húmeda y 21 días bajo agua potable filtrada. Así mismo, se estudia la variación del pH y de la concentración de los iones Ca (II, Mg (II, SO₄ (II y Cl (I de dicha agua de mar artificial ASTM, así como el contenido de los iones Ca (II, Mg (II y SO₄ (II de las mencionadas fases sólidas. La composición estructural de dichas fases sólidas y de la fracción enriquecida extraída de la probetas de mortero se determinó por DRX; de ello se dio cuenta en (3. En los casos estudiados se ha

Giant cemento-ossifying fibroma of the maxilla.

Science.gov (United States)

Unal, Adnan; Yurtsever Kum, Nurcan; Kum, Rauf Oguzhan; Erdogan, Aysun; Ciliz, Deniz Sozmen; Guresci, Servet; Ozcan, Muge

2015-11-14

Fibro-osseous lesions of the skull and facial bones are benign tumors, but they can be mistaken for malignant tumors due to their clinically aggressive behavior. Cemento-ossifying fibroma (COF) is a benign fibro-osseous lesion characterized by slow growth and fibrous and calcified tissue content. COFs are locally destructive lesions causing deformities in the bones. The recurrence risk is high if they are not completely removed. In this case report we describe a giant COF mimicking chondrosarcoma in the oral cavity of a 55-year-old woman causing significant facial deformity and feeding problems. Giant COF occurs rarely in the jaws and given that this lesion has similar imaging and clinical features to several other tumors, the diagnosis is always a challenge for clinicians, radiologists and pathologists.

Resistencia química del hormigón III.-Acción del agua de mar. Influencia de la adición de escoria al cemento portland (I. parte

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Gaspar-Tebar, Demetrio

1979-06-01

Full Text Available En publicaciones anteriores (1 (2 se dio cuenta de los trabajos efectuados para estudiar el comportamiento de dos cementos portland industriales, en la primera, y la influencia que ejerce la adición de diversas cantidades de una escoria vítrea a un cemento portland ambos de fabricación española, en la segunda, cuando los morteros (1:3 fabricados con dichos cementos o con las mezclas cemento/escoria se someten a la acción del agua de mar, determinando la evolución de las resistencias mecánicas a flexotracción, la variación de los coeficientes de corrosión (Kodi-Steinegger, la modificación de la concentración iónica de los medios en donde han estado sumergidas las probetas, así como la composición estructural de la fase sólida formada y de la fracción enriquecida del conglomerante hidratado.

Perfil logístico del sector del cemento en Colombia

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Londoño Floréz, Manuela; Pinto Cortes, Andres Felipe

2015-01-01

Este proyecto caracteriza la industria del cemento en Colombia a partir de la contextualización y descripción de esta actividad en el mundo y en el país, describiendo y analizando asuntos relacionados con la cadena de suministro de esta. Teniendo en cuenta los actores directos e indirectos que en esta interactúan y temas como el comercio internacional, el desempeño y la competitividad regional de la industria nacional, la percepción empresarial y factores como la responsabilidad social y las ...

Método simple para determinar el módulo de Young dinámico a partir de una excitación por impacto, aplicado a morteros de cal y cemento

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Rosell, J. R.; Cantalapiedra, I. R.

2011-01-01

El presente trabajo muestra un método simple para determinar el módulo de Young dinámico (MOE) a partir de pequeñas perturbaciones mecánicas producidas a probetas de mortero de cal y de cemento, correlacionando los resultados obtenidos con las correspondientes mediciones realizadas con otras técnicas. El procedimiento sigue básicamente las instrucciones fijadas en la norma UNE-EN ISO 12680-1 de productos refractarios, pero aplicándolo a probetas normalizadas RILEM 4x4x16 de morteros confec...

Análisis cuantitativo de cuarzo-alfa en mezclas de cemento portland anhidro y calcita sintética por difracción de rayos X con equipo Philips PW-1700

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Sagrera-Moreno, J. L.

1985-09-01

Full Text Available In this article there are explained the necessary steps to make up a quantitative analysis of alpha-quartz applying the technique of rays X diffraction, in artificial mixtures of anhydrous portland cement and synthetic calcite, which contents are known.

En el presente artículo se explican los pasos necesarios para realizar un análisis cuantitativo de cuarzo-alfa aplicando la técnica de difracción de rayos X en mezclas artificiales de cemento portland anhidro y calcita sintética, cuyos contenidos son conocidos.

Sobre lo constitución química del agua de amasado y los teorías de la hidratación del cemento

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Kittl, P.

1977-12-01

Full Text Available Se estudia la composición del agua de amasado (a/c = 0,5 de un cemento comercial, obteniendo que a los 10 minutos del comienzo se trata de una solución muy concentrada de KOH y NaOH con algo de CaOH, SO₄Ca, Al, Fe y vestigios de Si. La composición del agua de amasado a la 24 horas es similar. Evaporando estas soluciones no se encontró ninguna zona de composición del tipo CaO.H₂O.SiO₂ correspondiente a la familia de las tobermoritas y, por lo tanto, esto se inclina fuertemente a favor de la teoría topoquímica de la hidratación.

The polymer cement of sulfur as an alternative for the recycling of phosphogypsum. Corrosion testing of cements enriched with phosphogypsum; El cemento polimerico de azufre como alternative para el reciclado de fosfoyesos. Pruebas de corrosion de cementos enriquecidos con fosfoyesos

Energy Technology Data Exchange (ETDEWEB)

Gasco, C.; Lopez, F. A.; Navarro, N.; Sanchez, M.; Sanz, B.; Ballesteros, O.; Higueras, E.; Roman, C. P.

2011-07-01

The possibility of the use of cement for the recycling of materials is seen today as sustainable solution of the fertilizer industry for production of matches (NORM). In this paper presents some results of corrosion tests performed on these cements modified using buffer solutions of different pH. The analytical determinations in these matrices are new challenges. (Author)

Influence of relationship water/cement upon the processing of cements with pozzolana in standard mortar

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Gener Rizo, M.

2002-03-01

Full Text Available The processing of standard mortar is completed following different methods in accordance with the country, but they exist two fundamental tendecies, the ISO and the ASTM. The cuban norm for mechanic-physic tests is based in ISO, and so they use a constant relationship water/cement in the processing of standard mortar a great problem concerning the cement users when they tested those mixed with puzzolanes, because they don't take care of the bigger water needs of those materials. In this work we present an study of the behaviour of Pozzolanic Portland cements (PP-250 elaborates with a fix and changeable relationship water/cement, obtained starting from the fluidity of the pure Portland cement. (P-350 The results obtained shows that the mechanical resistance decreased in cement mortars PP-250 realised with changeable relationship water/cement. So we recommend the adoption of an optional procedure to elaborate a quality mortar with pozzolana cements.

La elaboración del mortero normalizado se realiza internacionalmente por diferentes métodos, pero existen dos tendencias fundamentales, la enunciada por ISO y por ASTM. La norma cubana de ensayos físico-mecánicos de cemento se basa en la norma ISO, por lo que para la elaboración del mortero normalizado se utiliza una relación agua/cemento constante. Esto ha provocado discrepancias con los usuarios del cemento, especialmente cuando se ensayan los cementos que contienen puzolanas, ya que se plantea que no se tiene en cuenta la mayor demanda de agua de estos materiales. En el presente trabajo se presenta un estudio del comportamiento de cementos Portland Puzolánicos (PP-250 elaborados con una relación agua/ cemento fija y variable, lograda a partir de la fluidez de la pasta de cemento Portland puro (P-350. Los resultados obtenidos indican que se producen disminuciones en la resistencia mecánica en los morteros de cemento PP-250 elaborados con agua/ cemento variable y recomienda la

Nuevos usos del cemento

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Páez Balaca, A.

1977-04-01

aislante de perlita. Por último se hace un estudio de los «hormigones ligeros», no de los clásicos usados como aislantes térmicos y acústicos, sino de aquéllos semipesados realizados con arcillas expandidas, arena de alta calidad y cemento P-450, cuya técnica en España no está todo lo desarrollada que fuera de desear.

Presencia y participación de la industria española en la producción de cemento en Iberoamérica

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Barón, José Ignacio

1977-09-01

Full Text Available Para considerar el grado y la influencia que en los últimos años la industria española ha tenido en el equipamiento del sector de la industria del cemento en Iberoamérica, es conveniente antes situar y definir, aunque sea en grandes trazos, en primer lugar la exportación española de bienes de equipo y maquinaria, y después la situación y evolución del subsector de empresas constructoras y suministradores de plantas de cemento en nuestro país.

Deconstrucción de la cubierta de asbesto-cemento del Mercado Central de Abastos de Alicante. Dificultades en la aplicación práctica del RD396/2006 (trabajos con riesgo de exposición al amianto)

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Sirvent Pérez, César Daniel

2010-01-01

El proyecto y las obras que a continuación se describen tratan principalmente sobre la deconstrucción de la cubierta actual de asbesto-cemento del Mercado Central de Abastos de Alicante para proceder a su sustitución por otra de escamas romboidales de zinc, semejante a la original que se ejecutó en 1921 cuando entró en servicio el edificio. Estas obras eran necesarias para evitar las causas (y también las consecuencias) que generan la aparición de filtraciones de agua de lluvia, tal y como qu...

Resistencia química del hormigón. XXIX.—Contribución al estudio del sistema Cemento P-550-ARI hidratado-disolución de sulfato de magnesio

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Gaspar-Tébar, Demetrio

1987-12-01

(II], que atraviesa los lechos granulados fabricados con dicho cemento hidratado y curado durante 7 y 28 días, determinando: a la evolución del contenido de los iones Ca (II, Mg (II y SO₄ (II de las diversas fracciones recogidas de la disolución de sulfato de magnesio, que han atravesado los lechos de cemento, así como la del pH y de la conductividad, b la variación de las cantidades de dichos iones, que se encuentran formando los compuestos correspondientes en el cemento hidratado de los lechos, antes y después de someterlos a la acción de la disolución de sulfato de magnesio, c las modificaciones estructurales experimentadas por los compuestos cristalinos del cemento hidratado de los lechos, sometidos a la acción de la disolución mencionada, y d las características químicas y estructurales de la nueva fase sólida formada en la disolución que ha atravesado los lechos de cemento.

Corrosion of high temperature resisting alloys exposed to heavy fuel ash; Corrosion de aleaciones resistentes a altas temperaturas expuestas a ceniza de combustoleo pesado

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Wong Moreno, Adriana del Carmen

1998-03-01

content of vanadium and very low content of sulfur at temperatures near the point of fusion of he vanadium compounds that constitute them. The development of the processes of metallic deterioration that are included in the proposed model was documented through this investigation, for an alloy range, from low alloy steels to nickel based super alloys, as well as for a series of ash deposits whose composition covers a part of the spectra of combinations of sodium/sulfate vanadates that little has been explored. Among the more relevant aspects that were documented and included in the proposed global mechanism, stand out the following ones: The global mechanism of corrosion by ashes of heavy fuel oil based on 3 primary processes of alloy degradation is described: metallic dissolution, accelerated oxidation and sulfidazation. The influence that the temperature and the composition of the ash on the predominance of one or another degradation mechanism has. It is also analyzed how the transformation of the underlying zone to the metal/deposit interphase by diffusion processes and precipitation accelerates the kinetics of degradation of the alloy, particularly, it has been considered the change in the concentrations of Cr, Al and Si, and the sulfide precipitation. Finally, the results obtained contribute in addition with practical information on the alloy performance, which allows to establish an order of merit among the evaluated alloys as far as its resistance to the corrosion, and on the roll of the main alloyings in its behavior of corrosion by fuel oil ash deposits. [Espanol] El objetivo de la investigacion realizada fue estudiar el proceso de degradacion por corrosion a alta temperatura de aleaciones expuestas a cenizas de combustoleo pesado a traves de una evaluacion experimental comparativa de su desempeno que permitio establecer los mecanismos involucrados en el fenomeno. La experimentacion llevada a cabo involucro la determinacion de la resistencia a la corrosion de 14

Shrinkage behaviour and related corrosion performance of low-pH cementitious materials based on OPC or CAC

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García-Calvo, J. L.

2016-03-01

Full Text Available Prior to using low-pH cementitious materials in underground repositories for high level waste, the characteristics determining their long-term durability must be analysed in depth. In this sense, different shrinkage tests have been made on mortar and concrete specimens using low-pH cement formulations based on ordinary portland cement (OPC or calcium aluminate cement (CAC, with high mineral admixtures contents. They showed similar autogenous shrinkage than samples without mineral admixtures but higher drying shrinkage when materials based on OPC with high silica fume contents were considered. Besides, as the use of reinforced concrete could be required in underground repositories, the susceptibility of reinforcement to corrosion when using low-pH cementitious materials based on OPC was analyzed, considering carbon steel and galvanized steel. In the formers corrosion was detected due to the low pore solution pH but any problem was detected when galvanized reinforcement were used.Previo al empleo de materiales con cementos de bajo pH en almacenamientos geológicos profundos (AGP de residuos radiactivos de alta actividad, características relacionadas con su durabilidad a largo plazo deben ser verificadas. Así, su estabilidad volumétrica se ha analizado en morteros y hormigones de bajo pH basados en OPC o CAC, con elevados contenidos de adiciones minerales. Estos presentaron retracciones autógenas similares a las medidas en materiales convencionales, pero retracciones por secado mayores en los basados en OPC y altos contenidos de humo de sílice. Dado que en zonas de los AGP podría emplearse hormigón armado, también se evaluó la susceptibilidad a la corrosión de aceros al carbono y aceros galvanizados en materiales de bajo pH basados en OPC. Se detectó un inicio temprano de corrosión en los primeros debido al bajo pH presente en el fluido de los poros de estos materiales, sin detectarse problemas al emplear aceros galvanizados.

Dictionary corrosion and corrosion control

International Nuclear Information System (INIS)

1985-01-01

This dictionary has 13000 entries in both languages. Keywords and extensive accompanying information simplify the choice of word for the user. The following topics are covered: Theoretical principles of corrosion; Corrosion of the metals and alloys most frequently used in engineering. Types of corrosion - (chemical-, electro-chemical, biological corrosion); forms of corrosion (superficial, pitting, selective, intercrystalline and stress corrosion; vibrational corrosion cracking); erosion and cavitation. Methods of corrosion control (material selection, temporary corrosion protection media, paint and plastics coatings, electro-chemical coatings, corrosion prevention by treatment of the corrosive media); Corrosion testing methods. (orig./HP) [de

Factores a tener en cuenta en la granulación de crudos para la fabricación de cemento

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Tonry, J. Richard

1960-12-01

Full Text Available Not availableEl estudio de los gránulos preparados con los crudos en tambores o artesas, así como aquellos nodulizados naturalmente en los hornos de vía húmeda, es reciente. Pero también puede decirse que, hasta la fecha se han estudiado con poco detenimiento en la Industria del cemento americana. En este trabajo se exponen y analizan los ensayos laboratorio de crudos procedentes de fábricas que usan nódulos en su proceso natural o por vía de experimentación. La granulación de crudos secos es necesaria en el uso de hornos del tipo de parrilla (Lepol, por ejemplo y puede practicarse también para preparar la alimentación para otros hornos rotatorios de vía seca. Los resultados varían con los diferentes crudos, en lo que se refiere al grado de perfección, para conseguir unos gránulos satisfactorios. La producción de nódulos húmedos no es difícil, como se evidencia por los resultados obtenidos con cinco crudos sin embargo, una vez secos, los gránulos procedentes de diferentes crudos varían mucho en sus propiedades. Dichos nódulos se ensayaron en capacidad bajo carga y en su resistencia a la abrasión en un amplio intervalo de temperaturas, pareciendo ser el más importante el ensayo de resistencia a la abrasión. En algunos casos, los aditivos químicos mejoran los nódulos. Las propiedades mineralógicas de los crudos tienen un efecto pronunciado sobre la consistencia del gránulo una vez seco. En este estudio se emplearon la difracción por rayos X y el análisis térmico diferencial.

Ant-nest corrosion of copper tubing in air-conditioning units

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Bastidas, D. M.

2006-10-01

Full Text Available Ant-nest corrosion is a specific type of premature failure (2-3 months of copper tubes used in air-conditioning units causing the loss of refrigerant liquid and the consequent environment pollution. It is known that attack requires the simultaneous presence of moisture, oxygen and a corrodent, usually an organic acid, such as formic, acetic, propionic or butyric acid or other volatile organic substances like methanol, ethanol, formaldehyde or acetoaldehyde. Approximately 10% of all premature failures of copper tubes used in the heating, ventilation and air-conditioning (HVAC industry are the result of ant-nest corrosion. This type of corrosion usually occurs in thin-wall copper pipes, especially when copper is de-sulphurised, and is known by several names: formicary corrosion, unusual corrosion, branched pits, pinhole corrosion, etc.

Corrosión por “nido de hormigas” es un tipo específico de fallo prematuro (2-3 meses que tiene lugar en tubos de cobre utilizados en sistemas de aire acondicionado originando la pérdida de líquido refrigerante y la consecuente contaminación ambiental. Es conocido que este tipo de ataque requiere la presencia simultánea de humedad, oxígeno y un medio agresivo, habitualmente un ácido orgánico, como fórmico, acético  propiónico o butírico u otras sustancias orgánicas volátiles tales como metanol, etanol, formaldehido o acetoaldehido. Aproximadamente el 10% de los fallos prematuros en tubos de cobre utilizados en calefacción, ventilación y en la industria de aire acondicionado son el resultado de corrosión por nido de hormigas. Frecuentemente, este tipo de corrosión tiene lugar en tubos de cobre de pared delgada, especialmente cuando el cobre es del tipo desulfurizado, y se conoce con varios nombres: corrosión por ácido fórmico, corrosión no habitual, picaduras ramificadas, corrosión con forma de alfiler, etc.

Aplicaciones prácticas de la espectroscopía de absorción infrarroja en el estudio de los crudos, del clínker y del cemento portland anhidro

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Vázquez, Tomás

1979-09-01

Full Text Available Not avaible

Con la presente publicación se inicia una serie de trabajos que pretenden ofrecer una visión práctica de la espectroscopía IR al aplicarla al estudio de las materias primas y del clínker y cemento portland. La aplicación principal de la espectroscopía IR se realiza sobre la Investigación dentro del ámbito de la Química del Cemento. Pensamos que la moderna industria del cemento necesariamente tendrá que acudir al empleo de esta técnica: el aumento constante de los precios de las materias primas, la carestía y la evolución de los costes de la energía, etc., lleva a la necesidad del conocimiento exhaustivo de los materiales y de sus procesos de transformación, para conseguir su máximo aprovechamiento. Este trabajo abarcará en su aspecto práctico el estudio de crudos empleados en la fabricación del clínker (caliza y arcilla, del propio clínker portland, del cemento anhidro con yeso, hemihidrato y/o singenita, de las adiciones inertes y activas (puzolanas, escorias y cenizas volantes así como del cemento con estas adiciones. Para la comprensión del mismo pensamos que es necesario dar una serie de consideraciones teóricas que se intentará sean lo más escuetas posibles.

Chondroblastic osteosarcoma arising in the maxilla mimicking the radiographic and histological characteristics of cemento-osseous lesions: A case report.

Science.gov (United States)

Li, Bin-Bin; Zhang, Jian-Yun; Gao, Yan

2017-05-01

Osteosarcomas of the jaw are comparatively rare and represent only 2-10% of all osteosarcomas. We herein present a rare case of an osteosarcoma exhibiting the radiographic and histological characteristics of cemento-osseous lesions in the alveolar ridge of the maxilla. A 53-year-old male patient presented with the complaint of gradual swelling of the left maxilla over 4 years. Radiography revealed an ill-defined radioopaque mass, intimately associated with the apices of the involved teeth, without a periosteal reaction. Microscopically, a cementicle-like structure was identified in the alveolar bone. In addition, the lesion exhibited typical characteristics of chondroblastic osteosarcoma in the body of the maxilla. The tumor contained abundant osteoid and cartilage intimately associated with anaplastic tumor cells. The cartilage displayed malignant-appearing cells in lacunae, and there was crowding at the periphery of the lobule where the spindle cells formed sheets. The differential diagnosis included primary osteosarcoma, concurrent cemento-osseous dysplasia and osteosarcoma, or a secondary osteosarcoma based on a pre-existing cemento-osseous lesion. The presence of the cementicle-like structure in the alveolar bone and the involvement of the periodontal ligament and alveolar bone proper were unique in our case. The general invasive growth pattern and the abundance of the irregular tumor bone helped establish the diagnosis of primary osteosarcoma. This case may represent evidence of the pathogenesis of primary osteosarcoma in the jaw.

Contribución al estudio de la resistencia química de los cementos. Comportamiento mecánico de un cemento portland resistente al yeso (1.ª Parte

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Gonzales-Vila, Victoriano

1985-06-01

Full Text Available This study, first part of a work where an account of the evolution of the mechanical resistances of various series of mortar and concrete tests submitted to the action of different agressive solutions will be given, sets up the chemical resistant behaviour of a sulphate resistant portland cement (with a content calculated —Bogue— null of C₃A, of 10,8% of C₄AF and of 81,7% of C₃S + C₂S against the CaSO₄.2 H₂O through the Le Chatelier-Anstett methods, and described in the ASTM C 452-73 and against the following agressive solutions: saturated solution calcium sulphate, Na₂SO₄ (2,1 g/l, MgSO₄.7H₂O (3,22 g/l, MgSO₄.7 H₂O (32,2 g/l, saturated of calcium sulphate + MgSO₄.7H₂O (3,22 g/l, saturated of calcium sulphate + MgSO₄.7H₂O (32,2g/l, Na₂SO₄ (3,5 g/l + NaCl (20,0 g/l, artificial sea water and, also, filtered drinking water, through of the Wittekindt and Kock Steinegger methods, during diverse periods, which allowed to establish a classification, according to his behaviour, of the studied cement against those agressive solutions.

En el presente trabajo, primera parte de otro en el que se dará cuenta de la evolución de las resistencias mecánicas de diversas series de probetas de mortero y de hormigón sometidas a la acción de distintas disoluciones agresivas, se estudia el comportamiento químico-resistente de un cemento portland industrial resistente al yeso (con un contenido calculado, Bogue, nulo de C₃A, del 10,8% de C₄AFy del 81,7% de C₃S + C₂S frente al CaSO₄.2 H₂O por los métodos de Le Chatelier-Anstett y el descrito en la norma ASTM C 452-73 y frente a las siguientes disoluciones agresivas: disolución saturada de sulfato de calcio, de Na₂SO₄ (2

Microbiological corrosion in low carbon steels; Corrosion microbiologica en aceros de bajo carbono

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Medina-Custodio, O; Ortiz-Prado, A; Jacobo-Armendariz, V. H; Schouwenaars-Franssens, R [Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico)]. E-mail: medina_1979@yahoo.com; armandoo@servidor.unam.mx; vjacobo@dgapa.unam.mx; raf_schouweenaars@yahoo.com

2009-01-15

The Microbiologically Induced Corrosion affects several industries, such as oil industry where it is estimated that 20% to 30% pipes failures are related with microorganism. The chemical reactions generate ions transfer, this validate the use of electrochemical technique for its analysis. Coupons submerged in a nutritional medium with presence and absence of three different microorganisms during two periods, 48 hours and 28 days were studied. Polarization resistance (Rp) and Electrochemical Impedance Spectroscopy (EIS) techniques were applied to determine the corrosively of the systems. The results show a greater corrosive effect of abiotic systems, this indicates a microorganisms protection effect to the metal, opposite to the first hypothesis. This result was ratified observing surface coupons by using Scanning Electron Microscopy (SEM) technique. A possible mechanism based on Evans - Tafel graph is proposed to explain inhibitor microorganism effect. [Spanish] La corrosion microbiologica es un tipo comun de deterioro que afecta diversas industrias, una de ellas es la petrolera en la que se estiman que el 20% o 30% de fallas en las tuberias de trasporte de hidrocarburos es favorecida por microorganismos. Las reacciones quimicas que sustentan estos, generan transferencia de iones, lo que justifica el empleo de tecnicas electroquimicas para su analisis. En este trabajo, se estudiaron probetas de acero de bajo carbono SAE 1018, sumergidas en un medio nutritivo rico en cloruros en presencia y ausencia de tres diferentes cargas microbianas, en tiempos de exposicion de 48 horas y 28 dias. Se realizaron ensayos de resistencia a la polarizacion (Rp) y espectroscopia de impedancia electroquimica (EIS) para determinar el efecto corrosivo de los diferentes sistemas. Los resultados muestran que el medio abiotico causa el mayor efecto corrosivo, lo que indica un efecto protector de los microorganismos al metal contradiciendo la hipotesis inicialmente propuesta. La observacion

Resistencia química del hormigón XXVI. Influencia de la adición de escoria a un cemento Portland. Estudio de la concentración iónica (del sistema cemento 3/escoria-agua de mar artificial

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Sagrera-Moreno, José Luis

1986-12-01

cement 3 and the mixture which has 15% slag in weight, have been submerged; in these means it has precipitated, in a part, as brucite. In the other means this ion is found in diverse quantities, according to the mixture and to the conservation-attack time. The content of SO₄ (II and Cl (I in the artificial sea-water has, in likewise experience, a decrease which depends on the mixture used in the manufacture of the mortar samples and the time of conservation-attack. The greatest quantities that have disappeared correspond to the means containing the mortar samples made with cement 3 and the mixtures with 15% and 35% slag, in weight, for the SO₄ (II ions and the mixtures with 35%, 60% and 70% slag for the Cl (I ions.

En el presente trabajo, continuación de otros, se estudia la evolución de la cantidad de nueva fase sólida formada en el agua de mar artificial ASTM D 1141-75 en donde han estado sumergidas las series de probetas de mortero (1:3 hechas con cemento portland (cemento 3/escoria = 85/15-65/35-40/60 y 30/70, en peso, durante 56-90-180 y 360 días (períodos de conservación-ataque, en esta etapa, después del período de curado (1 día en cámara húmeda y 21 días bajo agua potable filtrada. Así mismo, se estudia la variación del pH y de la concentración de iones Ca (II, Mg (II, SO₄ (II y Cl (I de dicha agua de mar artificial ASTM, así como del contenido de iones Ca (II, Mg (II y SO₄ (II de las mencionadas nuevas fases sólidas formadas. En los casos estudiados se ha puesto de manifiesto que en la disolución se ha producido un aumento de la concentración de Ca (II y del valor del pH, una disminución del contenido de Mg (II, SO₄ (II y Cl (I, así como la formación de una nueva fase sólida, que son función de la mezcla utilizada para fabricar las mencionadas series de probetas y del tiempo de conservación-ataque. Por otra parte, se ha probado que la evolución de los contenidos de Ca (II y

Caracterización mecánica de estructuras macroporosas fabricadas por extrusión aditiva de pasta cerámica

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González, Borja

2015-01-01

Los materiales destinados a la regeneración del tejido óseo han sido desarrollados durante las últimas décadas debido al incremento de enfermedades óseas motivadas por el envejecimiento de la población. Recientes trabajos en el campo de la ingeniería de tejidos se centran en este campo, concretamente en los cementos de fosfato de calcio y en su procesado como andamios usando técnicas de manufactura aditiva para conseguir injertos o materiales de relleno óseo con una adecuada os...

Cemento-osseous dysplasia of the jaw bones: key radiographic features.

Science.gov (United States)

Alsufyani, N A; Lam, E W N

2011-03-01

The purpose of this study is to assess possible diagnostic differences between general dentists (GPs) and oral and maxillofacial radiologists (RGs) in the identification of pathognomonic radiographic features of cemento-osseous dysplasia (COD) and its interpretation. Using a systematic objective survey instrument, 3 RGs and 3 GPs reviewed 50 image sets of COD and similarly appearing entities (dense bone island, cementoblastoma, cemento-ossifying fibroma, fibrous dysplasia, complex odontoma and sclerosing osteitis). Participants were asked to identify the presence or absence of radiographic features and then to make an interpretation of the images. RGs identified a well-defined border (odds ratio (OR) 6.67, P < 0.05); radiolucent periphery (OR 8.28, P < 0.005); bilateral occurrence (OR 10.23, P < 0.01); mixed radiolucent/radiopaque internal structure (OR 10.53, P < 0.01); the absence of non-concentric bony expansion (OR 7.63, P < 0.05); and the association with anterior and posterior teeth (OR 4.43, P < 0.05) as key features of COD. Consequently, RGs were able to correctly interpret 79.3% of COD cases. In contrast, GPs identified the absence of root resorption (OR 4.52, P < 0.05) and the association with anterior and posterior teeth (OR 3.22, P = 0.005) as the only key features of COD and were able to correctly interpret 38.7% of COD cases. There are statistically significant differences between RGs and GPs in the identification and interpretation of the radiographic features associated with COD (P < 0.001). We conclude that COD is radiographically discernable from other similarly appearing entities only if the characteristic radiographic features are correctly identified and then correctly interpreted.

Influencia del contenido en álcalis de los cementos sobre la corrosión de armaduras galvanizadas

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Andrade, C.

1981-12-01

Full Text Available Not available

Las armaduras galvanizadas han mostrado un comportamiento errático en los ensayos llevados a cabo hasta ahora, encontrándose en la literatura datos muy contradictorios. Los autores han encontrado que las siguientes tres variables tienen una decisiva importancia: a pH del mortero u hormigón, que depende básicamente de la cantidad de álcalis del cemento, b tipo de estructura metalográfica del recubrimiento galvanizado, que depende principalmente del tipo de acero y su contenido en Si y C, y c la humedad contenida en los poros del hormigón. En este trabajo se presentan resultados relacionados sólo con el punto a. Se ha podido comprobar que existe un valor de pH umbral o crítico por encima del cual el recubrimiento galvanizado se corroe severamente, debido a la formación de capas no-protectoras de productos de corrosión. La evolución de la velocidad de corrosión se ha seguido mediante la Resistencia de Polarización, y las pérdidas de peso se han determinado también, gravimétricamente.

Teoría de las restricciones (TOC) y la mecánica del Throughput Accounting (TA) Una aproximación a un modelo gerencial para toma de decisiones: caso compañía de Cementos Andino S.A.

OpenAIRE

González G., Patricia; Universidad del Valle; Escobar V., John Willmer; Pontificia Universidad Javeriana Cali

2008-01-01

El objetivo de este artículo es explicar a los lectores cómo a partir del modelo de decisión propuesto por la TOC y el TA, los gerentes pueden tomar las mejores decisiones orientadas a maximizar las utilidades del negocio. Para el logro del objetivo propuesto se empleó un caso centrado en la compañía Cementos Andino S.A., en el cual se desarrolló la metodología del TA, cuyos resultados fueron confrontados con los obtenidos a partir del costeo variable, de tal forma que los throughput obtenid...

Acción del agua de mar sobre un cemento portland de alta resistencia inicial y sobre un cemento portland resistente a los sulfatos: influencia de la adición de escoria. Estudio de la concentración iónica

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Gaspar-Tébar, Demetrio

1987-06-01

Full Text Available Not available

En este trabajo se estudia la variación del pH, así como la de la concentración de los iones Ca (II, Mg (II, SO₄ (II y Cl (I del agua de mar artificial (ASTM D 1141-75, en donde las probetas de mortero (1 : 3 de 1 X 1 X 6 cm fabricadas con un cemento portland industrial de alta resistencia inicial (cemento 1, con un cemento portland industrial resistente a los sulfatos (cemento 2 y con las mezclas cemento (1 ó 2/escoria = 85/15, 65/35, 40/60 y 30/70 (en peso han estado sumergidas, durante 56 - 90 - 180 y 360 días, después del período de curado (1 día en cámara húmeda y 21 días en agua potable; así mismo se estudia la evolución del contenido de Ca (II, Mg (II y SO₄ (II en la nueva fase sólida formada en el agua de mar artificial mencionada en donde han estado las probetas de mortero. En el agua de mar artificial se produce un aumento de la concentración de Ca (II y del valor del pH, una disminución de las cantidades de Mg (II, SO₄ (II y Cl (I, así como la formación de una nueva fase sólida, que son función de las mezclas cemento/escoria utilizadas para elaborar las probetas de mortero y del tiempo de conservación-ataque. El contenido de Ca (II, que procede del Ca(0H₂ disuelto del cemento hidratado, en el agua de mar artificial responde, prácticamente, a las cantidades calculadas a partir del Ca (II correspondientes al medio (agua de mar artificial en donde han estado las probetas fabricadas con los dos cementos estudiados, sin adición de escoria. La evolución de los contenidos de Ca (II y de Mg (II en el agua de mar artificial, en donde han estado las probetas, están íntimamente ligados, de tal modo que si la concentración de uno de ellos aumenta, la del otro disminuye y viceversa. Hay un sistema cemento/escoria - agua de mar artificial, para una mezcla determinada, en donde tiene lugar el equilibrio Ca (II que pasa a la disolución ⇌ Mg (II que

Resistencia química del Hormigón. XXVIII. Contribución al estudio del sistema Cemento P-550-ARI hidratado-disolución de sulfato de sodio

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Sagrera-Moreno, José L.

1987-06-01

fracciones recogidas de la disolución de sulfato de sodio, que han atravesado los lechos de cemento, así como la del pH y de la conductividad, b la variación de las cantidades de dichos iones, que se encuentran formando los compuestos correspondientes, en el cemento hidratado de los lechos antes y después de someterlos a la acción de la disolución de sulfato de sodio, c las modificaciones estructurales experimentadas por los compuestos cristalinos del cemento hidratado de los lechos sometidos a la acción de la disolución mencionada.

La celda Avesta: Un método para evitar problemas de corrosión por resquicios en los ensayos electroquímicos de corrosión por picaduras

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Fosca, C.

1996-06-01

Full Text Available A very common problem, that occurs during the electrochemical pitting corrosion tests of CRAs (corrosion resistant alloys as stainless steels, is the simultaneous occurrence of crevice corrosion that difficults the evaluation of the electrochemical behaviour in presence of pitting corrosion mechanism only. Crevice corrosion appears as a consequence of the formation of crevices during the mountage of the specimen in the electrochemical cell. Several forms have been developed to avoid the presence of crevice during the electrochemical pitting corrosion test, but without satisfactory results. In the present study a relatively new and innovative method to eliminate the risk of crevice corrosion in the electrochemical tests is evaluated the Avesta cell. Anodic polarization electrochemical tests were carried out in a high alloy stainless steel in 3 % NaCl solution. The experimental results obtained using the Avesta cell were more reliable, reproducible and representative of the electrochemical behaviour of the material that those obtained using other methods of samples preparation to avoid the crevice formation.

Uno de los grandes problemas que suelen presentarse en los ensayos electroquímicos ideados para evaluar la resistencia a la corrosión por picaduras de materiales como los aceros inoxidables es la presencia simultánea de corrosión por resquicios, que suele dificultar e impedir muchas veces la interpretación de los resultados electroquímicos. Este mecanismo de corrosión localizada se produce como consecuencia de la presencia de resquicios en el ensamble de la muestra con la celda electroquímica de ensayo. Se han ideado numerosas formas de evitar este inconveniente, pero ninguna ha resultado completamente satisfactoria. En el presente estudio se evalúa uno de los más nuevos e ingeniosos procedimientos para eliminar el riesgo de corrosión por resquicios en los ensayos de corrosión por picaduras: la celda Avesta. Se efectuaron

Resistencia química del hormigón XXV. Influencia de la adición de escoria a un cemento Portland. Estudio de la concentración iónica del sistema cemento 3/escoria-agua potable filtrada

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Sagrera-Moreno, José Luis

1986-06-01

Full Text Available This work, which follows on others, study the variation of the pH, and likewise the concentrations of the ions Ca (II and SO₄ (II of the filtered potable water in which there were submerged the test specimens of mortar (1:3 made with a Portland cement (cement 3 < > P-450 and with the mixtures cement 3/slag = 85/15 - 65/35 - 40/60 and 30/70 of weight, submerged for a curing period (21 days and later during 56 - 90 - 180 and 360 days (conservation periods, in this stage. It also study the chemical composition of the new solid phases formed in the said means. The structural composition of the solid phases (calcite was determined by DRX; an account of this was given in (2. In the different studied cases it has been demonstrated that an increase of the content of Ca (II in the solution and in the new solid phases and of the value of the pH is produced, which depends on the mixture used to manufacture the different test specimen series and on the time of conservation. The content of Ca (II in the solution is less than 0,1 X 10^-2 moles, in most of the cases, while in the new solid phases is greater, reaching 4,31 X 10^-2 moles. On the contrary the ion SO₄ (II has not been in the solid phases mentioned, being found in little quantities in the different liquid phases (filtered potable water; the greater contents correspond to the means of the mixture that have the greater mounts of slag (60 and 70 % of weight.

En el presente trabajo, continuación de otros, se estudia la variación del pH, así como de la concentración de los iones Ca (II y SO₄ (II del agua potable filtrada en donde han estado sumergidas las series de probetas de mortero (1:3 hechas con un cemento portland (cemento 3 < > < > P-450 y con las mezclas cemento 3/escoria = 85/15 - 65/35 - 40/60 y 30/70, en peso, durante el período de curado (21 días y, posteriormente, durante 56 - 90 - 180 y 360 días (períodos de conservaci

Propiedades mecánicas de morteros de cemento con adiciones de fibras de carbono, nanotubos de carbono y grafeno = Mechanical properties of cement mortars with additions of carbon fibres, carbon nanotubes and graphene

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María Ursúa Goicoechea

2017-12-01

Full Text Available El carbono es uno de los elementos más abundantes de la naturaleza. Su particular estructura hace que pueda tener hasta cinco tipos distintos de alótropos. Durante los últimos años se han producido grandes avances en el estudio de estos materiales de carbono. Las fibras de carbono (CF, los nanotubos de carbono (CNTs y el grafeno y óxido de grafeno (GO, en función de su estructura y su escala, presentan unas propiedades notablemente diferenciadas. Este estudio pretende comparar y determinar los efectos de estas características en matrices de cemento. Las características de estos materiales son difíciles de transmitir de forma exacta a los compuestos de cemento y hormigones, principalmente por las dificultades que presentan los nanomateriales en su dispersión. Por ello, los datos obtenidos en distintos estudios muestran resultados muy variables. Sin embargo, se ha demostrado que, para mejoras medias, los nanomateriales resultan ser más eficientes. Abstract Carbon is one of the most abundant elements of nature. Its particular structure has to have up to five different types of allotropes. During the last years there have been great advances in the study of these carbon materials. Carbon fibers (CF, carbon nanotubes (CNT and graphene and graphene oxide (GO, depending on their structure and scale, have remarkably different properties. This study aims to compare and determine the effects of these characteristics on cement matrices. The characteristics of these materials are difficult to transmit accurately to concrete and cement compounds, mainly due to the difficulties presented by nanomaterials in their dispersion. Therefore, the data obtained in different studies, results, very variable. However, it has been shown that, for average improvements, nanomaterials are more efficient.

Aplicaciones del cemento reforzado con fibra de vidrio (GRC

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Barros Llerena, Ángel

1981-12-01

Full Text Available Not available.

El presente artículo tiene como objeto dar a conocer la utilización de fibras de vidrio como refuerzo de los cementos. Se da una breve reseña histórica, se mencionan sus características y comportamiento. Además se presenta un caso práctico y reciente de utilización en la fabricación de elementos de fachada del Estadio «Santiago Bernabéu» del Real Madrid C. de F., y se completa con una relación de los actuales y futuros usos del G.R.C. (glass reinforced cement, denominación inglesa del material más comúnmente utilizado.

Basic aspects of the carbon dioxide corrosion in oil and gas production; Aspectos basicos de la corrosion por dioxido de carbono en la produccion de petroleo y gas

Energy Technology Data Exchange (ETDEWEB)

Angulo Macias, J.

2010-07-01

Carbon dioxide (CO{sub 2}) is a non-corrosive gas within the driven conditions in the oil and gas industry, but the presence of water converts it, maybe, in the most important component in the corrosive processes in this industry. Corrosion has an important impact inside the oil and gas companies, no only in economics but also in safety, environmental and social aspects. After several decades of investigation of these corrosion processes, there are still several mechanisms not fully understood. (Author) 19 refs.

Corrosion and corrosion control

International Nuclear Information System (INIS)

Khanna, A.S.; Totlani, M.K.

1995-01-01

Corrosion has always been associated with structures, plants, installations and equipment exposed to aggressive environments. It effects economy, safety and product reliability. Monitoring of component corrosion has thus become an essential requirement for the plant health and safety. Protection methods such as appropriate coatings, cathodic protection and use of inhibitors have become essential design parameters. High temperature corrosion, especially hot corrosion, is still a difficult concept to accommodate in corrosion allowance; there is a lack of harmonized system of performance testing of materials at high temperatures. In order to discuss and deliberate on these aspects, National Association for Corrosion Engineers International organised a National Conference on Corrosion and its Control in Bombay during November 28-30, 1995. This volume contains papers presented at the symposium. Paper relevant to INIS is indexed separately. refs., figs., tabs

Unión Andina de Cementos S.A.A. (UNACEM). Capital Structure Case

OpenAIRE

Lizarzaburu Bolaños, Edmundo R.; Burneo Farfan, Kurt; Berggun, Luis

2015-01-01

This present research paper, introduces one of the most important companies in the local market (Peru), Union Andina de Cementos S.A.A. (UNACEM). The company is engaged in the development and manufacture of clinker, cement and other building materials in the country and abroad, including marketing and sales as well as the operation of the dock facilities and complementary Conchan oil refinery. In the last years, their capital structure and their WACC changed because of the merger between Ceme...

Influencia de la adición del filler calizo sobre el fraguado del cemento

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Menéndez, Ignacio

1993-09-01

Full Text Available The present paper deals about the infuence that addition of calcareous "filler" has on the set of portland cement which rates are from 0 up to 50% of filler.

En el presente artículo se estudia la influencia que la adición de "filler" calizo ejerce sobre el fraguado del cemento portland, al que se le añaden porcentajes desde O al 50% en filler.

Hydration of tricalcium aluminate in the presence of gypsum

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Triviño Vázquez, F.

1974-06-01

Full Text Available Not availabePara el estudio del comportamiento del cemento Portland tiene una importancia fundamental el conocimiento de la hidratación del aluminato tricálcico, por ser uno de sus componentes que primero se hidrata y porque se le achacan la mayoría de los defectos que sufre la pasta de cemento; tales son: retracciones, contracciones, fenómenos exotérmicos y sensibilidad a agentes exteriores de tipo químico. En lo que sigue se estudia por métodos fisicoquímicos la hidratación del aluminato tricálcico junto con el yeso, ya que éste se emplea como regulador del fraguado en los cementos Portland.

Periapical cemento-osseous dysplasia: clinicopathological features.

Science.gov (United States)

Roghi, Marco; Scapparone, Chiara; Crippa, Rolando; Silvestrini-Biavati, Armando; Angiero, Francesca

2014-05-01

Periapical cemento-osseous dysplasia (PCOD) is a rare benign lesion, often asymptomatic, in which fibrous tissue replaces the normal bone tissue, with metaplasic bone and neo-formed cement. We present a rare case of mandibular PCOD in a woman of 55 years, who presented with moderate swelling and mobility of teeth 32-33-34. Endoral radiography showed that these teeth had been devitalized; they had deep periodontal pockets and marked radicular radiotransparency; the root apices exhibited mixed radiotransparency and radio-opacity. Clinical and radiographical findings led to a diagnosis of periapical rarefying osteitis, and the three teeth were thus extracted. Due to the persistence of swelling and slight pain post-extraction, a cone-beam computed tomographic scan was taken; this showed a mixed radiotransparent and radio-opaque lesion in the area of the extracted teeth. A bone biopsy of the affected area was taken for histopathological evaluation; a diagnosis of PCOD was rendered. This case demonstrates the importance of a full investigation when a patient presents after tooth extraction with non-healing socket, pain, and swelling. A multidisciplinary approach is required to manage these rare cases.

Corrosion of metallic materials. Dry corrosion, aqueous corrosion and corrosion by liquid metal, methods of protection

International Nuclear Information System (INIS)

Helie, Max

2015-01-01

This book is based on a course on materials given in an engineering school. The author first gives an overview of metallurgy issues: metallic materials (pure metals, metallic alloys), defects of crystal lattices (point defects, linear defects or dislocations), equilibrium diagrams, steels and cast, thermal processing of steels, stainless steels, aluminium and its alloys, copper and its alloys. The second part addresses the properties and characterization of surfaces and interfaces: singularity of a metal surface, surface energy of a metal, energy of grain boundaries, adsorption at a material surface, metal-electrolyte interface, surface oxide-electrolyte interface, techniques of surface analysis. The third chapter addresses the electrochemical aspects of corrosion: description of the corrosion phenomenon, free enthalpy of a compound and free enthalpy of a reaction, case of dry corrosion (thermodynamic aspect, Ellingham diagram, oxidation mechanisms, experimental study, macroscopic modelling), case of aqueous corrosion (electrochemical thermodynamics and kinetics, experimental determination of corrosion rate). The fourth part addresses the different forms of aqueous corrosion: generalized corrosion (atmospheric corrosion, mechanisms and tests), localized corrosion (galvanic, pitting, cracking, intergranular, erosion and cavitation), particular cases of stress cracking (stress corrosion, fatigue-corrosion, embrittlement by hydrogen), and bi-corrosion (of non alloyed steels, of stainless steels, and of aluminium and copper alloys). The sixth chapter addresses the struggle and the protection against aqueous corrosion: methods of prevention, scope of use of main alloys, geometry-based protection of pieces, use of corrosion inhibitors, use of organic or metallic coatings, electrochemical protection. The last chapter proposes an overview of corrosion types in industrial practices: in the automotive industry, in the oil industry, in the aircraft industry, and in the

Métodos electroquímicos semicuantitativos de estudio de lo corrosión por picaduras del acero para armaduras de hormigón

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Andrade Perdrix, M. C.

1977-12-01

Full Text Available El acero embebido en el hormigón se encuentra sometido a un medio de elevada alcalinidad (pH comprendido entre 12 y 13, debido a la cal libre, a los álcalis que contiene el cemento, y al Ca(0H₂ que se forma durante la hidratación de los silicatos. En esta situación, el acero se halla recubierto por una capa de óxidos e hidróxidos estables que lo mantienen pasivado, interponiendo una barrera entre él y los agentes agresivos.

Generalidades sobre Rocas y Análisis Químicos de Suelos.

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Orozco R. Aycardo

1940-06-01

Full Text Available Piedra caliza, o simplemente Caliza. La piedra caliza cuando tiene un alto grado de pureza y su dureza es de un alto título, su facilidad a la descomposición es escasa, debido a que las anteriores características la hacen resistente a la acción del agua carbonatada. Cuando su condición no es como la anterior, se desintegra con facilidad, dando origen a suelos muy ricos en Calcio, por consiguiente muy buenos para la agricultura, toda vez que el calcio es uno de los primordiales elementos biogenéticos. De allí el adagio popular, que no es otra cosa que la verdad virtualizando una frase: "Suelo calizo, es suelo rico". En general, la caliza es de fácil descomposición por su baja dureza, carácter éste que la ha, hecho aplicable el nombre que se le da en varios países: "'Piedra podrida". Cascajo, Gravas, Arenas, Conglomerados. Debido a la heterogeneidad física y mineralógica de estas su descomposición y los suelos resultantes están poco popularizados o democratizados. De ellas diré que sufren desintegraciones físicas acompañadas de variantes químicas, que van formando suelos cada vez más pesados, según concepto del doctor Shamblenberger. En las regiones húmedas, los suelos constituí dos por estas rocas son pobres para la vegetación, por la percolación que sufren los elementos biogeníticos que pasan al estado de solución. La naturaleza de los suelos a que dan origen depende en gran parte de dos factores: de la del cemento, que une las partículas de tales rocas, y del carácter de las partículas. En cuanto a la naturaleza del cemento, se hallará una razonable diferencia en descomposición si el cemento es cuarzoso o silicoso, si es calcáreo, ferruginoso, aluminoso o arcilloso y zoolítico. Es lógico que estas rocas con cemento silicoso exhibirán una mayor dificultad a su desintegración que las mismas en cualquiera de los otros cementos, ya que tal proceso se inicia por él. Cuando el cemento es calc

78 FR 59652 - Certain Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Notice of...

Science.gov (United States)

2013-09-27

... DEPARTMENT OF COMMERCE International Trade Administration [A-580-816] Certain Corrosion-Resistant... corrosion-resistant carbon steel flat products (``CORE'') from the Republic of Korea (``Korea''), pursuant... administrative review of the antidumping duty order on CORE from Korea covering the period of review (``POR'') of...

78 FR 59651 - Certain Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Notice of...

Science.gov (United States)

2013-09-27

... DEPARTMENT OF COMMERCE International Trade Administration [A-580-816] Certain Corrosion-Resistant... duty order on certain corrosion-resistant carbon steel flat products (``CORE'') from the Republic of... covering the period of review (``POR'') of August 1, 2006 through July 31, 2007, with respect to the...

Florid cemento-osseous dysplasia: Report of a case documented with clinical, radiographic, biochemical and histological findings.

Science.gov (United States)

Kutluay Köklü, Harika; Cankal, Dilek A; Bozkaya, Süleyman; Ergün, Gülfem; Bar, Emre

2013-02-01

Florid cemento-osseous dysplasia (FCOD) has been described as a condition that characteristically affects the jaws of middle-aged black women. This condition has also been classified as gigantiform cementoma, chronic sclerosing osteomyelitis, sclerosing osteitis, multiple estenosis and sclerotic cemental masses. It usually exhibits as multiple radiopaque cementum-like masses distributed throughout the jaws. Radiographically, FCOD appears as dense, lobulated masses, often symmetrically located in various regions of the jaws. Computed tomography, because of its ability to give axial, sagittal, and frontal views, is useful in the evaluation of these lesions. This article reports the case of a 45-year-old white man who was diagnosed with FCOD on the basis of clinical, radiographic, biochemical and histological findings. It is of major importance to realize that all dentists have a unique opportunity as well as ethical obligation to assist in the struggle against wrong dental treatments that might save patients dental health. This case report illustrates the point that periapical radiolucencies may represent benign fibro-osseous lesions that may be overlooked or result in unnecessary endodontic treatment. Key words:Florid cemento-osseous dysplasia, florid osseous dysplasia, fibro-osseous lesions.

Familial Florid Cemento-Osseous Dysplasia: A Rare Manifestation in an Indian Family

Science.gov (United States)

Srivastava, Adit; Agarwal, Rahul; Soni, Romesh; Sachan, Avesh; Shivakumar, G. C.; Chaturvedi, T. P.

2012-01-01

Florid cemento-osseous dysplasia (FCOD) is one of the uncommon dysplasias affecting the maxillofacial region. The age group may vary from 19 to 76 years and typically presents in the 4th and 5th decades. In most cases patients do not have hereditary basis of disease, and only a few familial cases have been documented. As far as we know this is the 1st reported case of familial FCOD in an Indian family. The mother and son exhibited multiple sclerotic masses in both jaws. The mode of transmission appeared to be autosomal dominant with variable phenotypic expression. PMID:23198165

Idiosyncratic Presentation of Cemento-Osseous Dysplasia - An in Depth Analysis Using Cone Beam Computed Tomography.

Science.gov (United States)

Chennoju, Sai Kiran; Pachigolla, Ramaswamy; Govada, Vanya Mahitha; Alapati, Satish; Balla, Smitha

2016-05-01

Bone dysplasias comprise of a condition where the normal bone is replaced with fibrous tissue. Periapical Cemento-Osseous Dysplasia (PCOD) is a benign fibro-osseous condition where bone tissue is supplanted with fibrous tissue and cementum-like material. This condition affects mostly mandibular anterior region and rarely occurs in the maxilla. PCOD is seen above 30 years of age and has slight female predilection. Generally the teeth related to such lesions appear to be vital and are usually asymptomatic. These lesions are mostly seen during routine radiographic examination whose presentation may vary from complete radiolucency to dense radiopacity. The advent of Cone Beam Computed Tomography (CBCT) has brought a massive change in the field of dentistry which has become an important tool for diagnosis. Hence we hereby present an unusual case of cemento-osseous dysplasia in an unfamiliar location with an atypical presentation. The shape of the pathology was completely idiosyncratic and different from an orthodox lesion of COD, as the lesion was observed to grow out of the palatal surface with a prominent palatal expansion. This case highlights the importance of CBCT in radiographic diagnosis and in evaluating the characteristics of such lesion, which present with high diagnostic dilemma.

Efecto del peso molecular del ácido poliacrílico y de la relación SiO2/Al2O3 en el vidrio sobre la resistencia mecánica de cementos de polialqueonato vítreo

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Méndez, M.

2002-08-01

mejor los procesos involucrados en las reacciones de formación de este tipo de cementos y de explorar su uso en aplicaciones ortopédicas, en el presente trabajo se realizó un estudio para analizar el efecto del peso molecular del ácido poliacrílico y de la proporción sílice/ alúmina sobre la resistencia a la compresión y las características microestructurales de cementos de polialquenoato vítreo. Las probetas obtenidas fueron sometidas a pruebas de compresión y al análisis por microscopía electrónica de barrido (MEB y por espectroscopía infrarroja por transformada de Fourier (IRTF. En una primera serie de experimentos se consideraron pesos moleculares promedio del ácido poliacrílico de 2000, 9700, 15268 y 64000, manteniéndose constante la relación SiO2/Al2O3 en un valor de 2,5. En una segunda serie de experimentos se consideraron relaciones SiO2/Al2O3 de 2,1; 1,67; 1,25; 0,95 y 0,8; utilizando ácido poliacrílico con peso molecular constante de 64000. Los máximos valores de resistencia mecánica (82,5 MPa se alcanzaron cuando el peso molecular del ácido poliacrílico fue de 64000 y la relación SiO2/Al2O3 en el vidrio fue de 1. Estos valores de resistencia a compresión de los cementos de polialquenoato vítreo son similares a los reportados para cementos a base de polimetilmetacrilato, lo cual sugiere su uso potencial en aplicaciones ortopédicas. Finalmente, se evaluó cualitativamente la reactividad de los vidrios y la presencia de grupos funcionales –COOH sin reaccionar utilizando IRTF, así como la separación de fases en vidrios con relaciones SiO2/Al2O3 > 1 y la reactividad superficial de las partículas de vidrio empleando espectroscopia de dispersión de rayos X (DERX en el MEB. A fin de optimizar la resistencia a compresión de los cementos de polialquenoato vítreo, trabajos futuros pueden ser orientados a mejorar la reactividad de los vidrios, a optimizar la relación polímero / vidrio y a utilizar partículas de vidrio de tama

System of lower cogeneration in the cement industry; Sistema de cogeneracion inferior en la industria del cemento

Energy Technology Data Exchange (ETDEWEB)

Romero Paredes, H.; Vazquez, A; Ambriz, J. J.; Fosado, A.; Cedillo, D.; Sanchez, R. [Universidad Autonoma Metropolitana-Iztapalapa (Mexico)

1999-07-01

In this paper present work, the design of a cogeneration system was made, taking advantage of the waste thermal flows in a cement manufacturing industry. The costs by concept of energy sources in the cement industry represent between 30 and 60% of the production costs, reason why any diminution in its consumption, will be reflected considerably in the productivity of the company. In order to determine the available capacity of waste energy and to establish the dimension of the cogeneration system it was decided to initially conduct balances of matter and energy of a cement production train. For the evaluation and numerical simulation a case study of a national plant was taken. The analysis takes only into account the rotary kiln, the pre roaster, the gas cooler or conditioner, the cooler of clinker and the separators or dust recuperators. In this study the electrical mills nor the systems that operate all over the plant have been taken in consideration. The results show that in general a high potential of co-generation exists since in some cases the heat losses can reach up to a 50% of the calorific energy input. The capacity of electrical generation by means of a steam turbine when taking advantage of a fraction (in the order of 60%) the residual heat, can be between 200 and 300 watts per kilogram of clinker produced. In conclusion, when recovering by means of appropriate heat exchangers for each one of the mentioned equipment the wasted energy and a network of heat interchange optimized by means of modern technologies an important part of the electrical energy that a cement mill uses can be generated. The method used has been very attractive and with the possibility of applying it to any cement mill and thus evaluate the potentials of energy co-generation. [Spanish] En el presente trabajo, se realizo el diseno de un sistema de cogeneracion aprovechando las corrientes termicas de desecho en una industria de fabricacion de cemento. Los costos por concepto de

Resistencia química del hormigón. XXI. Influencia de la adición de escoria a un cemento portland de alta resistencia inicial. Estudio de la concentración iónica del sistema cemento 1/escoria-agua potable filtrada

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Sagrera-Moreno, José Luis

1983-12-01

con las mezclas cemento 1/escoria = 85/15 - 65/35 - 40/60 y 30/70, en peso, durante el período de curado (21 días y, posteriormente, durante 56-90-180 y 360 días (períodos de conservación, en esta etapa. Así mismo, se estudia la composición química de las nuevas fases sólidas formadas en dichos medios. La composición estructural de dichas fases sólidas (calcita se determinó por DRX, de ello se dio cuenta en (2. En los distintos casos estudiados se ha puesto de manifiesto que se produce un incremento del contenido de Ca (II en la disolución y en las mencionadas fases sólidas, así como del valor del pH, que dependen de la mezcla utilizada para fabricar las diversas series de probetas y del tiempo de conservación. El Ca (II que se encuentra en la disolución (agua potable filtrada es menor de 0,1 X 10^-2 moles (en la mayoría de los casos es inferior a 0,07 X 10^-2 moles mientras que en la nueva fase sólida es mayor (normalmente, superior a 0,3 X 10^-2 moles. Por el contrario, el ion SO₄ (II no se ha detectado en las mencionadas fases sólidas, encontrándose en pequeñas cantidades en las diversas fases líquidas (agua potable filtrada; menor de 0,08 X 10^-2 moles en la mayoría de los casos.

Naturaleza del cemento en las areniscas del Flysch numidiense (sur de España

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Ruiz Cruz, M. D.

1990-04-01

Full Text Available Several size-fractions were centrifuged from the Aljibe sandstones to determinate both, nature and genesis of the cement. These samples are been analized by X-ray power diffraction, infrared spectroscopy, differential thermal analysis, termogravimetry and scanning electron microscopy. Two types of kaolinite were distinguished: Detrital kaolinite with low values of crystalIinity and b-parameter and authigenic kaolinite with higher values of crystallinity and b-parameter. Dickite is also presente in less extent. In the fractions analized, the detrital matrix is formed by disordered kaolinite, illite and mixed-layers illite/smectite. The cement is formed by ordered kaolinite, dickite and amorphous material. The controlling factors in the development of these materials are: primary porosity of sandstones, pore-fluid composition and burial.Se ha realizado el análisis de diferentes fracciones granulométricas en niveles deareniscas de la unidad del Aljibe con objeto de determinar la naturaleza y génesis del material cementante de las mismas. Las técnicas utilizadas han sido: Difracción de rayos X, espectroscopía de infrarrojos, análisis térmico diferencial, termogravimetría y microscopía electrónica de barrido. En función de los parámetros cristaloquímicos determinados han podido diferenciarse dos tipos de caolinita: Caolinita heredada, con valores bajos de la cristalinidad y del parámetro b0 y caolinita autigénica con valores elevados de la cristalinidad y de b0-. La dickita aparece bien desarrollada en ciertas secuencias. En las fracciones analizadas la matriz detrítica está constituida por caolinita desordenada, ilita e interestratificados ilita-esmectita. El cemento está constituido fundamentalmente por caolinita ordenada, dickita y materia amorfa. Los factores que han controlado el desarrollo de estos materiales han sido: porosidad primaria de las areniscas, composición de los fluidos intersticiales y grado de enterramiento.

Florid cemento-osseous dysplasia mimicking apical periodontitis: A case report.

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Rekabi, Ali Reza; Ashouri, Rezvan; Torabi, Molok; Parirokh, Masoud; Abbott, Paul V

2013-12-01

Cemento-osseous dysplasia may present as a focal, periapical or florid lesion in the mandible or maxilla. The lesion may sometimes appear similar to peri-radicular lesions on a periapical radiograph. This report presents a case with irreversible pulpitis and root resorption as well as a mixed radiolucent/radiopaque lesion around a mandibular molar tooth root. Root canal treatment was performed and because of the radiographic signs of root resorption and the patient's fear of having a malignant disease, periapical surgery was also performed. The histopathology report confirmed the presence of florid cement-osseous dysplasia which was mimicking apical periodontitis. Follow-up radiography 12 months after the surgery illustrated complete healing of the radiolucent area. © 2011 The Authors. Australian Endodontic Journal © 2011 Australian Society of Endodontology.

Reconstruction of maxillary cemento-ossifying fibroma defect with buccal pad of fat.

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Sivaraj, Subramonian; Jeevadhas, Pratheep

2013-07-01

A cemento-ossifying fibroma (COF) is a rare benign neoplasm of maxilla when compared with mandible (World Health Organization, 1992). COF of maxilla may be quite large and locally very aggressive lesion. These tumor mass was peeled out by en-bloc excision using gentle blunt dissection. This paper presents 35-year-old male patient who had a gradually expanding lobular mass in the left maxillary posterior region for past 1 year. He has been treated successfully by surgical en-bloc resection. Various techniques were used to reconstruction the defect. Buccal pad of fat is a simple technique having advantages like good vascularity, adaptability, good closure of the defect with favorable prognosis.

COMPORTAMIENTO DE UN CEMENTO ASFÁLTICO MODIFICADO CON UN DESECHO DE PVC

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Fredy Alberto Reyes Lizcano

2013-06-01

Full Text Available Las propiedades físicas y reológicas a altas temperaturas de servicio de un cemento asfáltico (CA modificado con un desecho de policloruro de vinilo (PVC fueron evaluadas y son presentadas en el artículo. Adicionalmente se presenta la influencia del tiempo de mezcla del CA con el PVC y el envejecimiento a corto plazo. Un incremento notable en la rigidez y la resistencia a fluir se reporta cuando se adiciona el desecho de PVC a un CA 80-100. De la misma forma, se reporta un incremento en la temperatura máxima de operación en servicio del ligante modificado.

[Progress in the diagnosis of florid cemento-osseous dysplasia].

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Zhang, P Y; Xiao, C

2018-04-09

Florid cemento-osseous dysplasia (FLCOD) is a rare, extensive bone metabolism disorder, which occurs only in the jaw bone. It is usually asymptomatic for a long time and discovered incidentally during a radiological examination. The characteristics of FLCOD in the initial stages are similar to those of periapical granuloma or jaw cyst, which may lead to misdiagnosis. After the lesion is mature, the imaging findings show that radiopaque with a thin radiolucent peripheral halo, which is crucial for the diagnosis of FLCOD, but other jaw lesions have similar imaging findings. Due to the poor blood supply of the lesion, the alveolar bone of root apices of vital teeth is slow to heal after trauma, increasing the chance of infection, which can lead to the osteomyelitis of the jaws and emerge sequestrum. This paper reviews the aspects of pathogenesis, clinical characteristics, diagnosis, differential diagnosis and treatment.

Cemento-ossifying fibroma of mandible mimicking complex composite odontome.

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Dewan, Hitesh Sudarshan; Dewan, Sudarshan Kumar; Bahl, Sumit; Tushar Parekh, Parth

2016-10-19

Cemento-ossifying fibroma (COF) is a fibro-osseous lesion or non-odontogenic tumour that affects craniofacial bones. These lesions are included in the spectrum of fibro-osseous lesions arising from periodontal ligament cells, which can deposit combination of cementum and bone surrounded by fibrous tissue. It clinically, macroscopically and radiologically resembles complex composite odontome and can be differentiated only on the basis of histopathology. They usually occur solitarily as a painless and expansile spherical or ovoid jawbone mass that may displace the roots of adjacent teeth. They predominantly occur in females in third and fourth decades of life. We present a case report of a 20-year-old man, with a mildly painful swelling in the mandible which was successfully treated with enucleation and diagnosed as COF. Its resemblance to complex composite odontome and unique surgical approach are highlighted in this paper. 2016 BMJ Publishing Group Ltd.

Idiosyncratic Presentation of Cemento-Osseous Dysplasia – An in Depth Analysis Using Cone Beam Computed Tomography

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Pachigolla, Ramaswamy; Govada, Vanya Mahitha; Alapati, Satish; Balla, Smitha

2016-01-01

Bone dysplasias comprise of a condition where the normal bone is replaced with fibrous tissue. Periapical Cemento-Osseous Dysplasia (PCOD) is a benign fibro-osseous condition where bone tissue is supplanted with fibrous tissue and cementum-like material. This condition affects mostly mandibular anterior region and rarely occurs in the maxilla. PCOD is seen above 30 years of age and has slight female predilection. Generally the teeth related to such lesions appear to be vital and are usually asymptomatic. These lesions are mostly seen during routine radiographic examination whose presentation may vary from complete radiolucency to dense radiopacity. The advent of Cone Beam Computed Tomography (CBCT) has brought a massive change in the field of dentistry which has become an important tool for diagnosis. Hence we hereby present an unusual case of cemento-osseous dysplasia in an unfamiliar location with an atypical presentation. The shape of the pathology was completely idiosyncratic and different from an orthodox lesion of COD, as the lesion was observed to grow out of the palatal surface with a prominent palatal expansion. This case highlights the importance of CBCT in radiographic diagnosis and in evaluating the characteristics of such lesion, which present with high diagnostic dilemma. PMID:27437374

Periapical cemento-osseous dysplasia: a case report with twelve-year follow-up and review of literature.

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Senia, E S; Sarao, M S

2015-11-01

To present a case report describing the long-term behaviour of periapical cemento-osseous dysplasia by observing the radiographic changes that took place over a period of 12 years. A review of the pertinent literature is also presented. A healthy 26-year-old white female was referred to the Wilford Hall USAF Medical Center Endodontic Department for evaluation of an asymptomatic radiolucency at the apex of the right mandibular lateral incisor. Following a clinical evaluation that included pulp testing, a diagnosis of periapical cemento-osseous dysplasia (PCOD) was made. No treatment was rendered but follow-up visits were recommended. The patient was subsequently re-evaluated 8 times over a period of 12 years. During that time the lesion changed in appearance, displaying the various phases of PCOD. At the same time, lesions affecting the three adjoining incisors appeared and behaved in a similar manner. At the 12-year recall, the right lateral and both central incisors revealed no evidence of PCOD and an almost normal trabecular pattern of bone could be seen. Misdiagnosis and unnecessary treatment of PCOD may be avoided with careful pulp testing and knowledge of its most common locations of occurrence, radiographic appearances (phases) and benign behaviour. © 2014 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Associated aneurysmal bone cyst and cemento-osseous dysplasia: a case report and review of the literature.

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Jacomacci, Willian Pecin; Veloso Perdigão, João Paulo; Veltrini, Vanessa Cristina; Farah, Gustavo Jacobucci; Tolentino, Elen Souza; Vessoni Iwaki, Lilian Cristina; Iwaki Filho, Liogi

2017-01-01

The purpose of this case report is to describe a previously unpublished association between focal cemento-osseous dysplasia (FCOD) and an aneurysmal bone cyst (ABC) and review the literature with regard to associated benign fibro-osseous lesions and cysts. A 41-year-old woman without a history of trauma presented with asymptomatic swelling in the right side of the mandible. Radiographs of the region revealed a unilocular radiolucent area with radiopaque foci. After aspiration of the lesion was positive for serosanguineous fluid, complete excision of the lesion was performed. Microscopic examination revealed a hybrid ABC and FCOD. The 12-month follow-up showed significant bone repair and no signs of recurrence. A review of the English-language literature from 1980 to 2012 revealed 1 retrospective study, 4 case series, and 18 single-case reports on the topic of cemento-osseous dysplasias, fibro-osseous lesions, and aneurysmal bone cysts. Of 59 cases, none reported an association between an ABC and FCOD. Although fibro-osseous lesions do not require intervention, surgical excision is recommended when they are associated with cysts. This case, in which an ABC and FCOD were associated, reinforces the need for a careful diagnostic process in radiographically mixed lesions that respond positively to aspiration biopsy.

Influencia de los componentes minoritarios de los carbones en la fabricación de cementos

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Soria Santamaría, Francisco

1982-09-01

Full Text Available As a consequence of the reconversion of coal in the cement industry, it is considered important to analyze the incorporation and transcendence of certain components in the clinkerisation process. Given in detail are the circuits of gases and volatile materials used in the baking process, emphasizing the interest of sulphur, alkalis, chlorides and fluorides. Emphasized are the conditions and limits imposed in practice to certain components and the possibilities of application of the carbons in this sense. Finally, a brief comment is made to the emission of dusts and contaminating gases, emphasizing the incidence in this field with the use of solid fuels in the furnaces to manufacture cement.

Como consecuencia de la reconversión al carbón en la industria cementera, se considera importante analizar la incorporación y trascendencia de ciertos componentes en el proceso de clinkerización. Se expone con detalle los circuitos de gases y materias volátiles en el proceso de cocción, destacando el interés del azufre, álcalis, cloruros y fluoruros. Se destacan las condiciones y límites impuestos por la práctica a ciertos componentes y las posibilidades de aplicación de los carbones en este sentido. Finalmente, se hace un breve comentario a la emisión de polvo y gases contaminantes, precisando la incidencia en este campo con el empleo de combustibles sólidos en los hornos para fabricar cemento.

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

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Monfore, G. E.

1966-03-01

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

Sulphate attack on brickwork

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Editorial, Equipo

1960-03-01

Full Text Available Not availablePara que ocurra un ataque por sulfatos han de estar presentes tres materiales: cemento Portland, sulfatos solubles y agua. Si concurren estos tres componentes y, particularmente, si la obra de fábrica ha de permanecer húmeda largo tiempo, los sulfatos reaccionarán con el cemento, motivando expansión, pérdida de resistencia y, finalmente, desintegración. Si sólo se encuentran presentes dos de estos materiales, no surgirá perturbación alguna; según esto, el cemento Portland y los sulfatos solubles pueden coexistir en la fábrica de ladrillo, siempre que ésta .se encuentre seca. Por lo tanto, es conveniente considerar, en primer término, en qué extensión la obra contiene estos tres materiales.

Resistencia química del hormigón. XIX. Acción de una disolución saturada de yeso: influencia de la adición de escoria a un cemento Portland. Evolución de las resistencias mecánicas a flexotracción y de los coeficientes de corrosión

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Sagrera-Moreno, José Luis

1983-03-01

Full Text Available In the present paper, third of the new series started with and industrial portland cement, there is studied the influence exerted by the addition of different quantities of slag to an industrial portand cement (cement 3 < > P-450 in its chemical-resistant behavior when subjected, during various periods of time, to the action of a saturated dissolution of gypsum determining the evolution of the chemical resistance by the Koch-Steinegger method, as well as the mechanical resistances to flexotraction of mortar specimens (1:3 of 1 X 1 X 6 cm manufactured with the cement 3 and with the mixtures cement 3/slag = 85/15, 65/35, 40/60 and 30/70 in weight, sinking in filtered potable water a series of twelve (12 specimens and in a saturated dissolution of gypsum similar to the previous one, during 56-90-180 and 360 days, after having cured them during twenty four (24 hours in an enclosure saturated of humidity at 20 ± 2°C and, following, twenty one (21 days under filtered potable water. In this work there has been shown the favorable action that, from a mechanical-resistant point of view, is exerted by the addition of slag, in a special manner, of high quantities, to cement 3.

En el presente trabajo, tercero de la nueva serie iniciada con un cemento portland industrial, se estudia la influencia que ejerce la adición de distintas cantidades de escoria a un cemento portland industrial (cemento 3 < > P-450 en su comportamiento químico-resistente cuando se somete, durante diversos períodos de tiempo, a la acción de una disolución saturada de yeso, determinando la evolución de la resistencia química por el método de Koch-Steinegger, así como de las resistencias mecánicas a flexotracción de probetas de mortero (1:3 de 1 X 1 X 6 cm fabricadas con dicho cemento 3 y con las mezclas cemento 3/escoria = 85/15, 65/35, 40/60 y 30/70, en peso, sumergidas en agua potable filtrada unas series de 12 probetas y en una disolución saturada de yeso otras

Evaluación a lo largo del tiempo de las propiedades mecánicas de los bloques de suelo-cemento utilizados en pavimentos semipermeables

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M. Carvalho

Full Text Available Un pavimento semipermeable fue construido con una capa de revestimiento de bloques de suelo-cemento hechos de suelo de desmonte (estabilizado con 30% de arena y cemento (con 20% de la mezcla y fabricados con una prensa. Este tipo de bloque no tiene estudios adicionales acerca de las mudanzas del comportamiento de las propiedades mecánicas a lo largo del tempo, entonces para realizar el estudio se seleccionaron algunos bloques (con 7, 14, 28, 130 y 1650 días de moldeado para medir las propiedades mecánicas (de durabilidad, de absorción de agua y de resistencia a compresión sencilla. Los resultados demostraron que no hubo mudanzas en las propiedades de absorción y de durabilidad de los bloques, después de 1650 días. La resistencia a la compresión tuvo un leve incremento de 9MPa (28 días de moldeados para 12MPa (1650 días de moldeados, bloques del pavimento en uso, lo que puede ser atribuido a las reacciones que todavía suceden entre cemento, suelo y agua o a la variabilidad de materia prima y de los equipamientos utilizados. Concluyese que las condiciones ambientales y el tráfico leve no afectaron las propiedades mecánicas de los bloques, entonces ellos pueden ser utilizados en pavimento semipermeable.

A Test With Small Dimension Cylinders for the Rapid Determination of the Quality of Cement

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Dalziel, J. A.

1972-09-01

Full Text Available Not availableSe han confeccionado cilindros de ensayo, de tamaño miniatura, compactando por presión cemento seco hasta obtener una porosidad inicial constante. Seguidamente se curaron a 20 ºC, después de que los poros intergranulares se rellenasen con agua, utilizando para ello una técnica de vacío. Las probetas resultantes, constituidas únicamente por cemento y agua (sin áridos ni aire, presentan bajos coeficientes de: resistencia (2%, peso (0,2%, longitud (0,1% y relación agua-cemento (1,3%. La rápida ganancia de resistencias de los minicilindros permite conocer las resistencias, según las British Standard, a 3 y 7 días en tan sólo 8 y 12 horas, respectivamente. Se ha observado que un cierto número de tipos de cemento mantienen, en lo que se refiere a resistencias, una clara correspondencia. El procedimiento de ensayo que se propone tiene la ventaja de requerir solamente pequeñas cantidades de cemento, menor gasto en el equipo y reducida cantidad de mano de obra. Mediante la eliminación de ciertas variables, implicadas en este método de ensayo para la determinación de la calidad del cemento, y reduciéndose otras, puede haber una mayor oportunidad para mejorar la coordinación entre los resultados obtenidos en los diferentes laboratorios.

Diseño sustentable de materiales de construcción; caso del concreto de matriz de cemento Pórtland

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Silverio Hernández Moreno

2008-01-01

Full Text Available El presente documento contiene una revisión sobre diseño sustentable aplicado a materiales de construcción, particularmente del concreto de cemento Pórtland; en donde se establecen los principales criterios y métodos para el manejo sustentable de los materiales de construcción a través del ciclo de vida de los materiales y de los edificios. Se menciona la necesidad de tener prácticas sustentables encaminadas a la reducción del impacto al ambiente y reducción de los costos de materiales de construcción, mediante la justa aplicación del diseño sustentable. En el caso práctico, queda definido que podemos disminuir el impacto ambiental mediante el uso de estrategias y métodos diversos para la selección y aplicación de materias primas dentro de los procesos de construcción, principalmente mediante la aplicación de los métodos de recuperación de materiales y de manejo sustentable de materias primas, tales como: reuso, reciclamiento, refabricación y recuperación de energía por materiales de construcción.

Low-alkali cement from high-efficiency kilns?

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Clausen, C. F.

1960-06-01

Full Text Available Not availableHace unos veinte años, la industria del cemento mantiene una vigilancia extrema del efecto, a veces pernicioso, de los álcalis en el hormigón, esta industria reconoce, por otro lado, la necesidad de fabricar cementos bajos en álcalis, cuando se han de emplear para determinados usos.

Idiosyncratic Presentation of Cemento-Osseous Dysplasia – An in Depth Analysis Using Cone Beam Computed Tomography

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Chennoju, Sai Kiran; Pachigolla, Ramaswamy; Govada, Vanya Mahitha; Alapati, Satish; Balla, Smitha

2016-01-01

Bone dysplasias comprise of a condition where the normal bone is replaced with fibrous tissue. Periapical Cemento-Osseous Dysplasia (PCOD) is a benign fibro-osseous condition where bone tissue is supplanted with fibrous tissue and cementum-like material. This condition affects mostly mandibular anterior region and rarely occurs in the maxilla. PCOD is seen above 30 years of age and has slight female predilection. Generally the teeth related to such lesions appear to be vital and are usually a...

Durabilidad del hormigón: Influencia de la adición de escoria a un cemento Portland resistente a los sulfates. Acción del agua de mar y de una disolución saturada de yeso

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Gaspar-Tebar, Demetrio

1990-03-01

Full Text Available This article studies the influence of addition of different quantities of slag and compares this with the addition of fine particled silica sand. The mortar samples (1:3 of 1 x 1 x 6 cm —prepared with a sulphate-resistent portland cement, mixed with a selected slag and with silica sand were subjected to the action of artificial sea water ASTM and to a saturated plaster disolution for different periods of time (3 years for the first and 1 year for second ones. The performance of the following factors was determined: the mechanical resistence (to flexotraction, the Koch-Steinegger corrosion coefficients, the structural composition of the new solid phases formed in the cured medium and the preservation-attack. The following were also examined: the hidrated-attacked cement paste and its mixes with the slag and the silica sand taken from the mortar sample, and the variation in concentration of Ca (II and Mg (II ions. The performance in mechanical resistence of samples of mortar measuring 4 x 4 x 16 cm and of concrete measuring 10 x 10 x 40 cm were also studied in this way. These samples were made with the aforementioned cement and subjected to the action of the said disolutions for different periods of time (up till 5 years. Finally, an account is given of work which has been started on this subject at a selected area at the Autonomous Port of Huelva.

En este artículo se estudia la influencia de la adición de distintas cantidades de escoria, comparándola con la adición de arena silícea, finamente molida, cuando las probetas de mortero (1:3 de 1 x 1 x 6 cm —preparadas con un cemento portland resistente a los sulfates, con sus mezclas con una escoria seleccionada y con la arena silícea— se someten a la acción del agua de mar artificial ASTM y de una disolución saturada de yeso durante diversos períodos de tiempo (hasta 3 años las primeras y 1 año las segundas, determinando la evolución de las resistencias mecánicas (a

Adenomatoid odontogenic tumor with peripheral cemento-osseous reactive proliferation: report of 2 cases and review of the literature.

Science.gov (United States)

Naidu, Aparna; Slater, Lee J; Hamao-Sakamoto, Aya; Waters, Patrick; Kessler, Harvey P; Wright, John M

2016-09-01

Two cases of a rare variant of adenomatoid odontogenic tumor encompassed by a prominent reactive cemento-osseous proliferation are reported. This unique variant of adenomatoid odontogenic tumor has only been seen twice in the authors' collective experience. Literature documenting the histopathologic patterns of adenomatoid odontogenic tumor and the occurrence of other combined lesions other is reviewed and discussed. Copyright © 2016 Elsevier Inc. All rights reserved.

A new method in estimation of total hexavalent chromium in Portland pozzolan cement; Un nuevo método en la determinación del cromo hexavalente total en cemento Portland puzolánico.

Energy Technology Data Exchange (ETDEWEB)

Sharma, R.; Sharma, D.

2017-07-01

Variamine blue was used first time for the detection of hexavalent chromium from cement samples. In present method, cement was treated sequentially with water, sulphate and carbonate buffer to extract soluble, sparingly soluble and insoluble hexavalent chromium respectively. Extracted Cr (VI) was determined using variamine blue as chromogenic reagent. The determination is based on the reaction of hexavalent chromium with potassium iodide in an acid medium to liberate iodine. This oxidizes variamine blue to form a violet coloured species having an absorption to maximum at 556 nm. Energy-dispersive X-ray spectroscopy (EDX) and Infrared Spectroscopy (IR) confirmed the complete extraction of hexavalent chromium by sequential extraction process. SRM 2701 (Reference material from NIST, USA) was used for revalidating the results. The percentage of recovery for proposed and reference method (diphelycarbazide method) varied from 98.5 to 101 and 97.5 to 100.5. Whereas, their relative error percentage varied from -1.5 to 0.33 and -2.5 to 0.5. [Spanish] El azul de variamina se utilizó por primera vez para la detección de cromo hexavalente en muestras de cemento. En el presente método, el cemento se trató secuencialmente con agua, y tampones sulfato y carbonato para extraer el cromo hexavalente soluble, poco soluble e insoluble, respectivamente. El Cr (VI) extraído se determinó utilizando azul de variamina como reactivo cromógeno, por reacción del cromo hexavalente con yoduro de potasio en un medio ácido para liberar yodo. Esto oxida al azul de variamina para formar una especie de color violeta con una absorción máxima a 556 nm. El análisis por energía dispersiva de rayos X (EDX) y la espectroscopía de infrarrojos (IR) confirmaron la extracción completa de cromo hexavalente mediante el proceso de extracción secuencial. Se utilizó SRM 2701 (material de referencia de NIST, EE.UU.) para validar los resultados. El porcentaje de recuperación para el m

Clinical, radiographic, and histological findings of florid cemento-osseous dysplasia: a case report

International Nuclear Information System (INIS)

Kim, Jeong Hee; Song, Byeong Chul; Kimn, Sun Ho; Park, Yang Soon

2011-01-01

Cemento-osseous dysplasias are a group of disorders known to originate from periodontal ligament tissue and involve, essentially, the same pathological process. They are usually classified into three main groups: periapical, florid, and focal cemental dysplasias depending on their extent and radiographic appearances. Radiographically, florid cementoosseous dysplasia (FCOD) appears as dense, lobulated masses, often symmetrically located in various regions of the jaws. The best management for the asymptomatic FCOD patient consists of regular recall examinations with prophylaxis. The management of the symptomatic patient is more difficult. A case of FCOD occurring in a 52-year-old edentulous Korean female is reported which is rare with regard to race and sex.

Clinical, radiographic, and histological findings of florid cemento-osseous dysplasia: a case report.

Science.gov (United States)

Kim, Jeong-Hee; Song, Byeong-Chul; Kim, Sun-Ho; Park, Yang-Soon

2011-09-01

Cemento-osseous dysplasias are a group of disorders known to originate from periodontal ligament tissue and involve, essentially, the same pathological process. They are usually classified into three main groups: periapical, florid, and focal cemental dysplasias depending on their extent and radiographic appearances. Radiographically, florid cementoosseous dysplasia (FCOD) appears as dense, lobulated masses, often symmetrically located in various regions of the jaws. The best management for the asymptomatic FCOD patient consists of regular recall examinations with prophylaxis. The management of the symptomatic patient is more difficult. A case of FCOD occurring in a 52-year-old edentulous Korean female is reported which is rare with regard to race and sex.

Cemento-ossifying fibroma of mandible: An unusual case report and review of literature.

Science.gov (United States)

Mohapatra, Mounabati; Banushree, C S; Nagarajan, K; Pati, Debashish

2015-01-01

The term ossifying fibroma (OF) has recently been included under fibro-osseous lesions. Cemento-OF (COF) is a benign neoplasm that arises from the periodontal membrane which contains multipotential cells that are capable of forming cementum, lamellar bone and fibrous tissue. These tumors occur in the third and fourth decades of life with a predilection for women. The mandible is more commonly involved than the maxilla. This lesion has caused considerable controversy regarding the use of terminology, origin and diagnostic criteria. This article describes an unusual case of COF presenting as unilocular lytic lesion of mandible in a 38-year-old male patient with review of literature.

Clinical, radiographic, and histological findings of florid cemento-osseous dysplasia: a case report

Energy Technology Data Exchange (ETDEWEB)

Kim, Jeong Hee; Song, Byeong Chul; Kimn, Sun Ho; Park, Yang Soon [Seoul Veterans Hospital, Seoul (Korea, Republic of)

2011-09-15

Cemento-osseous dysplasias are a group of disorders known to originate from periodontal ligament tissue and involve, essentially, the same pathological process. They are usually classified into three main groups: periapical, florid, and focal cemental dysplasias depending on their extent and radiographic appearances. Radiographically, florid cementoosseous dysplasia (FCOD) appears as dense, lobulated masses, often symmetrically located in various regions of the jaws. The best management for the asymptomatic FCOD patient consists of regular recall examinations with prophylaxis. The management of the symptomatic patient is more difficult. A case of FCOD occurring in a 52-year-old edentulous Korean female is reported which is rare with regard to race and sex.

Recubrimientos bioactivos sobre aleaciones de titanio depositados por la técnica sol-gel

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Claudia García

2006-01-01

Full Text Available Entre los materiales de uso ortopédico, los metales son de amplio uso, principalmente por las exigencias mecánicas que cumplen durante el uso. A pesar de ello, los metales presentan limitaciones importantes como la degradación in situ y la necesidad de cementación o fijación externa. Estas restricciones afectan la integridad estructural de la prótesis y producen elementos resultantes de la corrosión ante los cuales el organismo produce respuestas adversas. Una opción para minimizar la liberación de productos de corrosión por parte de los implantes metálicos al organismo, es el desarrollo de recubrimientos cerámicos o vítreos. Si además, los recubrimientos poseen material bioactivo, no se hace necesario utilizar fijación externa o cemento para generar la unión con el hueso. En el presente trabajo se describe la metodología para depositar recubrimientos doble capa con partículas bioativas producidos por la técnica sol-gel sobre la aleación Ti6Al4V y se caracteriza el material recubierto en cuanto a su resistencia a la corrosión mediante ensayos electroquímicos en fluido fisiológico simulado (SBF y en cuanto a su bioactividad mediante ensayos in vitro.

Influencia de la humedad en el ensayo de resistencia de los ladrillos de suelo-cemento

OpenAIRE

Lima, José I.; Escobar Martín, Dunia

1994-01-01

A través de un diseño experimental adecuado se pretende mostrar la influencia de la humedad en el ensayo a compresión de los ladrillos de suelo-cemento, obteniendo las ecuaciones que muestran esta relación. Su generalización posterior permitió elaborar una matriz de correlación de las resistencias con las diferentes humedades de ensayo, de forma tal que se pueda ensayar con una humedad dada y estimar la resistencia que tendrá esa muestra para diferentes valores de humedad, con un buen nive...

Sobre la determinación de la calidad de las escorias de horno alto y de las puzolanas

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Wittekindt, W.

1964-06-01

Full Text Available Not availableEn la molienda de clínker portland con escoria de horno alto para obtener cemento portland de hierro y cemento de horno alto, uno está más seguro de la calidad del clínker que de la escoria. El análisis del clínker y el cálculo de los minerales de clínker, facilitado por este análisis, nos dice ya, en gran parte, si se puede fabricar con este clínker un cemento portland de mayor o menor resistencia, si pueden esperarse buenas resistencias iniciales o si hay que contar más bien con mayores resistencias finales, cual es la resistencia del cemento a los sulfatos, etc.

Corrosion

Science.gov (United States)

Slabaugh, W. H.

1974-01-01

Presents some materials for use in demonstration and experimentation of corrosion processes, including corrosion stimulation and inhibition. Indicates that basic concepts of electrochemistry, crystal structure, and kinetics can be extended to practical chemistry through corrosion explanation. (CC)

Evaluation of the physical and electrochemical properties of adobe reinforced and of its component materials

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Pérez, G.

2004-06-01

.28.10^-8 for (MBA-adobe-MRD. The specimens test tubes were exposed to the natural environment during 200 days, being there been dew with water previous to the measures, the corrosion potentials and the corrosion rate were moderate weekly during the days of exhibition. These results in durability terms indicate that the greater benefit in this type of systems and with the smaller cost is obtained improving the quality of the mortar that is used like stucco. Also one concluded according to the values of Porosity and Capillary Absorption the greater than to 19% and 2.23.10^-4 respectively, that the analyzed walls of adobe reinforced are not adapted for aggressive atmospheres if it is taken like reference because these properties are very below the established standards.

La búsqueda de soluciones a la crisis de vivienda que existe en Latinoamérica ha favorecido al uso del suelo-cemento-sisal en muros portantes de adobe reforzado como material alternativo de construcción. En tal sentido, resulta imperante determinar la vulnerabilidad de una construcción de este tipo, es por ello que, la caracterización de las propiedades físicas, mecánicas y electroquímicas de los materiales que la componen, ayuda a relacionar las causas externas de deterioro con las internas. En este caso particular se estudió la permeabilidad, la porosidad, la absorción capilar, los potenciales de Cu/CuSO₄ y la velocidad de corrosión del adobe reforzado, de los componentes y de los muros. En el aspecto metodológico, se utilizó un permeabílimetro de Figg. modificado para determinar la permeabilidad al agua y el método de Fagerlund para medir la absorción capilar, la porosidad se determinó siguiendo métodos tradicionales, los potenciales se midieron utilizando un multímetro y las velocidades de corrosión con el corrosómetro, Gecor 6. Se ensayaron dos grupos de probetas: un primer grupo de los materiales componentes: adobe, mortero para friso y mortero de

Effect of supplementary cementing materials on the concrete corrosion control

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Mejía de Gutiérrez, R.

2003-12-01

Full Text Available Failure of concrete after a period of years, less than the life expected for which it was designed, may be caused by the environment to which it has been exposed or by a variety of internal causes. The incorporation of supplementary materials has at the Portland cement the purpose of improving the concrete microstructure and also of influence the resistance of concrete to environmental attacks. Different mineral by-products as ground granulated blast furnace slag (GGBS, silica fume (SF, metakaolin (MK, fly ash (FA and other products have been used as supplementary cementing materials. This paper is about the behavior of concrete in the presence of mineral additions. Compared to Portland cements, blended cements show lower heat of hydration, lower permeability, greater resistance to sulphates and sea water. These blended cements find the best application when requirements of durability are regarded as a priority specially on high performance concrete.

La falla del concreto en un tiempo inferior a la vida útil para la cual se diseñó puede ser consecuencia del medio ambiente al cual ha estado expuesto o de algunas otras causas de tipo interno. La incorporación de materiales suplementarios al cemento Portland tiene el propósito de mejorar la microestructura del concreto y también de contribuir a la resistencia del concreto a los ataques del medio ambiente. Diferentes minerales y subproductos tales como escorias granuladas de alto horno, humo de sílice, metacaolín, ceniza volante y otros productos han sido usados como materiales suplementarios cementantes. Este documento presenta el comportamiento del hormigón en presencia de diferentes adiciones. Los cementos adicionados, comparados con los cementos Portland muestran bajos calores de hidratación, baja permeabilidad, mayor resistencia a sulfatos y a agua de mar. Estos cementos adicionados encuentran un campo de aplicación importante cuando los requerimientos de durabilidad son

Problemas de construcción y de explotación· de los grandes hornos rotatorios por vía seca

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Münk, R.

1963-06-01

Full Text Available Not availableSe indican las consideraciones que han incitado a la industria del cemento a construir grandes unidades de hornos por vía seca. Se describen los métodos que hoy se encuentran en el mercado. Se compara la economía térmica de algunos hornos por vía seca, dedicando especial atención a la recuperación de calor de los gases y al funcionamiento del enfriador. Se explican las enseñanzas características especiales de estas grandes unidades. Se trata de la eliminación de polvo y cuestiones de dosificación del combustible y del crudo, así como problemas del desgaste y de la conservación del precalentador de la chapa del homo y del enfriador. Se discute el consumo de calor teóricamente más económico y se muestran los problemas a resolver para ponerlo en práctica.

Desarrollo de un cemento de base silicatada a partir de rocas volcánicas vítreas alcalinas: interpretación de los resultados preindustriales basada en la composición químico-mineralógica de los precursores geológicos

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Gimeno, D.

2003-04-01

Full Text Available The GEOCISTEM project was focussed to look for an inexpensive natural glassy alkaline substitute of chemical reagents used in a trade registered cement. A complete survey for european resources made up for fragmentary (pyroclastic alkali-rich glassy volcanic rocks (Na2O+K2O > 10 %, K>>Na was done in several european volcanic regions (in Italy, Greece and Spain. Up to 100 samples were analysed (main constituents by XRF; petrographic and XRD characterisation and 10 of them were used in the developing of a silicate-based cement (laboratory and semi-industrial scale.The result was a set (ten of cements characterised by high compressive strength of the plain cement phase (50-60 MPa after 28 days, with high resistance to chemical corrosion and non alkali-silica-aggregate reaction, very indicated for toxic waste encapsulation. Furthermore a great economy in energy and a significant reduction of K-silicate consumption (up to 1/3-1/4 of the formulation in the original trade registered cement in the process of production was achieved. The chemical-mineralogical study carried out shows that the original formulation of the cement was too restrictive, as well as that the mineralogy reached during natural devitrification processes in the rock strictly controls the performance of this new european resource during the development of the cement. The anhidrous rocks mainly constituted by alkali feldspars and silica crystalline phases (obtained by devetrification at temperatures under magmatic ones are more interesting than the zeolitised ones, allowing to skip the calcination process and thus providing energetic economy.

El proyecto GEOCISTEM intentó hallar un substituto vítreo alcalino natural, económico y viable industrialmente, a los reactivos químicos empleados en un cemento silicatado patentado. Se realizó una completa prospección de los recursos consistentes en rocas volcánicas vítreas ricas en álcalis (Na2O+K2O > 10 %, K

Finite element model for expansive stress due to corrosion of reinforced concrete structures; Analisis con elemento finito de los esfuerzos expansivos por corrosion en las estructuras de concreto reforzado

Energy Technology Data Exchange (ETDEWEB)

Castorena Gonzalez, J.H.; Calderon Guillen, J.A. [Universidad Autonoma de Sinaloa, Los Mochis, Sinaloa (Mexico)]. E-mail: kstor28@yahoo.com.mx; cajoel_99@yahoo.com; Almeraya Calderon, F.; Gaona Tiburcio, C. [Centro de Investigacion en Materiales Avanzados, S.C., Chihuahua, Chihuahua (Mexico)]. E-mail: facundo.almeraya@cimav.edu.mx; citlalli.gaona@cimav.edu.mx; Almaral Sanchez, J.L. [Universidad Autonoma de Sinaloa, Los Mochis, Sinaloa (Mexico)]. E-mail: jalmaral@gmail.com; Martinez Villafane, A. [Centro de Investigacion en Materiales Avanzados, S.C., Chihuahua, Chihuahua (Mexico)]. E-mail: martinez.villafane@cimav.edu.mx

2011-01-15

The corrosion in the reinforcement steel is a problem that diminishes the useful life of reinforced concrete structures, reside committing its structural security. In the available models to estimate the mechanical effect of the corrosion, it is assumed that the corroded steel, through the oxides that grow to its surroundings, exercises a pressure on the surrounding concrete supposing a problem of plane stress or plane strain. In this work, the problem is modeled with three-dimensional finite element starting from an experiment on a subjected cylinder to accelerated corrosion, with strain gage to measure the pressure indirectly in the interface steel-concrete. From the results obtained it can be concluded that the effect of the length of corroded steel, anodic length, has a significant effect on the magnitude of the pressure in the interface steel-concrete, fact that can be used to improve the existing models. [Spanish] La corrosion en el acero de refuerzo es un problema que disminuye la vida util en las estructuras de concreto reforzado, ademas de comprometer su seguridad estructural. En los modelos disponibles para estimar el efecto mecanico de la corrosion, se supone que el acero corroido, a traves de los oxidos que crecen a su alrededor, ejercen una presion sobre el concreto circundante suponiendo un problema de esfuerzos o deformaciones planas, En el presente trabajo, se modela el problema con elemento finito tridimensional a partir de un experimento sobre un cilindro de concreto reforzado sometido a corrosion acelerada, instrumentado para medir indirectamente la presion en la interfase acero-concreto. De los resultados obtenidos se concluye que el efecto de la longitud de acero corroido, longitud anodica, tiene un efecto significativo sobre la magnitud de la presion en la interfase acero-concreto, hecho que puede ser utilizado para mejorar los modelos existentes.

Corrosion in airframes

OpenAIRE

PETROVIC ZORAN C.

2016-01-01

The introductory chapter provides a brief reference to the issue of corrosion and corrosion damage to aircraft structures. Depending on the nature and dimensions of this non uniformity, three different categories of corrosion are defined: uniform, selective and localized corrosion. The following chapters present the forms of corrosion that can occur in three defined categories of corrosion. Conditions that cause certain types of corrosion in various corrosive environments are discussed. Examp...

Corrosion engineering

Energy Technology Data Exchange (ETDEWEB)

Fontana, M.G.

1986-01-01

This book emphasizes the engineering approach to handling corrosion. It presents corrosion data by corrosives or environments rather than by materials. It discusses the corrosion engineering of noble metals, ''exotic'' metals, non-metallics, coatings, mechanical properties, and corrosion testing, as well as modern concepts. New sections have been added on fracture mechanics, laser alloying, nuclear waste isolation, solar energy, geothermal energy, and the Statue of Liberty. Special isocorrosion charts, developed by the author, are introduced as a quick way to look at candidates for a particular corrosive.

Peripheral cemento-ossifying fibroma: A case report with review of literature.

Science.gov (United States)

Mishra, Amit Kumar; Maru, Rahul; Dhodapkar, Shrikant Vishnuprasad; Jaiswal, Gagan; Kumar, Rajesh; Punjabi, Heena

2013-06-16

Peripheral cemento-ossifying fibroma (PCOF) is a rare osteogenic neoplasm that ordinarily presents as an epulis-like growth. This is of a reactive rather than neoplastic nature and its pathogenesis is uncertain. PCOF predominantly affects adolescent and young adults with greatest prevalence around 28 years. We report here a rare clinical case of PCOF of the mandible, 1 cm mesiodistally and 1.5 cm occluso-gingivally in diameter, which caused difficulty in eating and speech, in a 42-year-old female patient. She was asymptomatic for 1 year and on follow-up for 6 mo post surgically showed gingival health and normal radioopacity of bone without any recurrence. Clinical, radiographic and histological characteristics are discussed and recommendations regarding differential diagnosis, treatment and follow up are provided. The controversial varied nomenclature and possible etiopathogenesis of PCOF are emphasized.

Achievments of corrosion science and corrosion protection technology

International Nuclear Information System (INIS)

Fontana, M.; Stehjl, R.

1985-01-01

Problems of corrosion-mechanical strength of metals, effect of corrosive media on creep characteristics are presented. New concepts of the mechanism of corrosion cracking and its relation to hydrogen embrittlement are described. Kinetics and mechanism of hydrogen embrittlement effect on the process of corrosion cracking of different steels and alloys are considered. The dependence of such types of failure on various structural factors is shown. Data on corrosion cracking of high-strength aluminium and titanium alloys, mechanism of the processes and protective methods are given

Reutilización de residuos de edificación para el desarrollo de materiales cementantes con características especiales

OpenAIRE

Morales Martínez, Laura María

2010-01-01

La industria de la producción de cemento es una de las más rentables a escala mundial aunque también es una de las más contaminantes, ya que la producción de cemento supone la emisión de CO2, un gas de efecto invernadero implicado en el cambio climático, por eso, una de las prioridades de la industria cementera es reducir la cantidad de estas emisiones contaminantes. Por otro lado, el incremento de la concienciación ambiental en el sector de la construcción hace que se refle...

Erosion–corrosion and corrosion properties of DLC coated low temperature Erosion–corrosion and corrosion properties of DLC coated low temperature

DEFF Research Database (Denmark)

Jellesen, Morten Stendahl; Christiansen, Thomas; Hilbert, Lisbeth Rischel

2009-01-01

of AISI 316 as substrate for DLC coatings are investigated. Corrosion and erosion–corrosion measurements were carried out on low temperature nitrided stainless steel AISI 316 and on low temperature nitrided stainless steel AISI 316 with a top layer of DLC. The combination of DLC and low temperature...... nitriding dramatically reduces the amount of erosion–corrosion of stainless steel under impingement of particles in a corrosive medium....

Determinación de la resistencia del hornnigón en viguetas fabricadas con cemento aluminóso

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de la Fuente Sánchez, Antonio

1993-03-01

Full Text Available Not Available.

La resistencia de los hormigones en viguetas de cemento aluminóso es uno de los parámetros más solicitados a los laboratorios de control. La dificultad de su determinación estriba en la gran cantidad de armaduras que suelen llevar las alas de la vigueta, siendo el alma la única zona de la que pueden extraerse muestras de hormigón.

Aspectos de la evolución de la industria italiana del cemento durante el último quinquenio (1955-1959

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Malquori, Giovanni

1961-03-01

Full Text Available Not availableComo acabo de decir, hace ahora cinco años que tuve el grato honor de describir, en este mismo Centro, la evolución de la industria italiana del cemento, desde sus comienzos, en la segunda mitad del siglo pasado, hasta nuestros días, y de ilustrar brevemente los resultados conseguidos, tanto en el sector de la producción como en el de las aplicaciones.

Resistencia química del hormigón. XV-Acción de una disolución saturada de yeso: influencia de la adición de escoria a un cemento portland de alta resistencia inicial. Evolución de las resistencias mecánicas a flexotracción y de los coeficientes de corrosi

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Sagrera-Moreno, José Luis

1982-03-01

Full Text Available In this work, the first of another new series, a study is made on the influence brought by adding different quantities of a groundgranulate slag to a high initial resistance industrial portland cement (cement 1 < > P-550-ARI in its chemical-strength behaviour against the action of a gypsum saturated solution, determining the evolution of the chemical resistance using the Koch-Steinegger method, as well a tensile strengths of mortar test specimens (1:3 of 1 x 1 x 6 cm made with this cement 1 and with mixtures cement 1/slag = 85/15 - 65/35 - 40/60 and 30/70, in weight immersed in drinking water with some series of 12 test speciments filtered and other series that are analogue to the above, in a gypsum saturated solution, for 56-90-180 and 360 days, after curing them in a humidity saturated area at 20 ± 2°C, and later, 21 days under filtered drinking water. The favourabe action exerted by adding slag has been evident, especialy in high amounts (≥ 60 % to cement 1 studied.

En el presente trabajo, primero de otra nueva serie, se estudia, la influencia que ejerce la adición de distintas cantidades de una escoria granulada molida a un cemento portland industrial de alta resistencia inicial (cemento 1 < > P-550-ARI en su comportamiento químico-resistente frente a la acción de una disolución saturada de yeso, determinando la evolución de la resistencia química por el método de Koch-Steinegger, así como la de las resistencias mecánicas a flexotracción de probetas de mortero (1:3 de 1 x 1 x 6 cm, fabricadas con dicho cemento 1 y con las mezclas cemento 1/escoria = 85/15 - 65/35 - 40/60 y 30/70, en peso, sumergidas en agua potable filtrada unas series de 12 probetas y en una disolución saturada de yeso otras series análogas a las anteriores, durante 56-90-180 y 360 días, después de haberlas curado 24 horas en un recinto saturado de humedad a 20 ± 2°C y, a continuación, 21 días bajo agua potable filtrada. Se ha puesto de

Quick analysis method of sulphuric anhydride

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Puig Montraveta, J.

1974-09-01

Full Text Available Not availableEl clinker de cemento portland molido sin adición alguna da un cemento que fragua inmediatamente, y la escoria de alto horno, molida asimismo sin adición, nos proporciona un producto que fragua muy lentamente. Ambos requieren la adición de un retardador o de un acelerante que les regule su fraguado. El sulfato calcico, ya sea en forma de sulfato cálcico dihidratado o yeso (CaS04.2H20 o como sulfato cálcico anhidro o anhidrita (CaSO4, actúa como regulador de fraguado en los dos casos, y por ello se añade en la molienda de los cementos portland, siderúrgicos, sobresulfatados, puzolánicos, etc.; todo lo cual obliga a que el sulfato cálcico deba considerarse como materia prima para la producción de todos los cementos, a excepción del cemento aluminoso fundido.

Florid cemento-osseous dysplasia: A rare case report evaluated with cone-beam computed tomography.

Science.gov (United States)

Yildirim, Eren; Bağlar, Serdar; Ciftci, Mehmet Ertugrul; Ozcan, Erdal

2016-01-01

A 29-year-old systemically healthy female patient presented to our department. Cone-beam computed tomographic images showed multiple well-defined sclerotic masses with radiolucent border in both right and left molar regions of the mandible. These sclerotic masses were surrounded by a thin radiolucent border. We diagnosed the present pathology as florid cemento-osseous dysplasia and decided to follow the patient without taking biopsy. For the patient, who did not have any clinical complaints, radiographic followupis recommended twice a year. The responsibility of the dentist is to ensure the follow-up of the diagnosed patients and take necessary measures for preventing the infections.

Corrosion Evaluation and Corrosion Control of Steam Generators

International Nuclear Information System (INIS)

Maeng, W. Y.; Kim, U. C.; Sung, K. W.; Na, J. W.; Lee, Y. H.; Lee, D. H.; Kim, K. M.

2008-06-01

Corrosion damage significantly influences the integrity and efficiency of steam generator. Corrosion problems of steam generator are unsolved issues until now even though much effort is made around world. Especially the stress corrosion cracking of heat exchange materials is the first issue to be solved. The corrosion protection method of steam generator is important and urgent for the guarantee of nuclear plant's integrity. The objectives of this study are 1) to evaluate the corrosion properties of steam generator materials, 2) to optimize the water chemistry of steam generator and 3) to develop the corrosion protection method of primary and secondary sides of steam generator. The results will be reflected to the water chemistry guideline for improving the integrity and efficiency of steam generator in domestic power plants

Durabilidad del hormigón: Acción de disoluciones de sulfato de calcio y de sulfato de magnesio sobre un cemento Portland de alta resistencia inicial. Influencia de la adición de escorias y de cenizas volantes

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Sagrera-Moreno, José Luis

1990-09-01

Full Text Available This article —included on a long time ICCET Investigation Program— studies the mechanical resistances variation, to flexure, of the 1 X 1 X 6 cm mortar samples (1:3 made with high initial resistance cement and with several slags addition (cement/slag = 85/15 - 65/35 - 40/60 and 30/70 with high furnace slag and a fly ash (with selected characteristies when they were submited after the cured period (1 day at 100% R.H. and 21 days inside filtered potable water to the action of the gypsum saturated solution, four magnesium sulphate solutions with the next concentrations (3.22 - 32.20 - 128.80 and 515.20 g/l of MgS0₄4.7H₂0, gypsum saturated solution with 3.22 g/l MgS0₄.7H₂0 a gypsum saturated solution with 32.20 g/l MgSO₄. 7H₂O and, moreover, filtered potable water, during 56-90-180- 360 - 540 - 720 - 900 and 1080 days. The results obtained have produced a clasification accord to the mechanical behaviour to flexure of the cement n. ° 1 and the mixed cement n.° 1/slag and cement n.° 1/fly ash, front to the agressive solutions mentioned.

En este artículo —que forma parte de un Proyecto de Investigación del ICCET, a largo plazo— se estudia la variación de las resistencias mecánicas, a flexotracción, de las probetas de mortero (1:3 de 1 X 1 X 6 cm hechas con un cemento portland de alta resistencia inicial y con sus mezclas (cemento/adición = 85/15 - 65/35 - 40/60 y 30/70, en peso con una escoria de horno alto y una ceniza volante (seleccionadas de entre diversas muestras por sus características cuando se someten después del período de curado (1 día en cámara húmeda y 21 días bajo agua potable filtrada a la acción de una disolución saturada de yeso, cuatro disoluciones de sulfato de magnesio con distintas concentraciones (3,22 - 32,20 - 128,80 y 515,20 g/l de MgSO₄.7 H₂O, una disolución saturada de yeso con 3,22 g/l de MgS0₄

Corrosion-Activated Micro-Containers for Environmentally Friendly Corrosion Protective Coatings

Science.gov (United States)

Li, Wenyan; Buhrow, J. W.; Zhang, X.; Johnsey, M. N.; Pearman, B. P.; Jolley, S. T.; Calle, L. M.

2016-01-01

This work concerns the development of environmentally friendly encapsulation technology, specifically designed to incorporate corrosion indicators, inhibitors, and self-healing agents into a coating, in such a way that the delivery of the indicators and inhibitors is triggered by the corrosion process, and the delivery of self-healing agents is triggered by mechanical damage to the coating. Encapsulation of the active corrosion control ingredients allows the incorporation of desired autonomous corrosion control functions such as: early corrosion detection, hidden corrosion detection, corrosion inhibition, and self-healing of mechanical damage into a coating. The technology offers the versatility needed to include one or several corrosion control functions into the same coating.The development of the encapsulation technology has progressed from the initial proof-of-concept work, in which a corrosion indicator was encapsulated into an oil-core (hydrophobic) microcapsule and shown to be delivered autonomously, under simulated corrosion conditions, to a sophisticated portfolio of micro carriers (organic, inorganic, and hybrid) that can be used to deliver a wide range of active corrosion ingredients at a rate that can be adjusted to offer immediate as well as long-term corrosion control. The micro carriers have been incorporated into different coating formulas to test and optimize the autonomous corrosion detection, inhibition, and self-healing functions of the coatings. This paper provides an overview of progress made to date and highlights recent technical developments, such as improved corrosion detection sensitivity, inhibitor test results in various types of coatings, and highly effective self-healing coatings based on green chemistry. The NASA Kennedy Space Centers Corrosion Technology Lab at the Kennedy Space Center in Florida, U.S.A. has been developing multifunctional smart coatings based on the microencapsulation of environmentally friendly corrosion

Propiedades térmicas, acústicas y mecánicas de placas de mortero caucho-cemento.

OpenAIRE

Bustamante Montoro, Rosa; Mayor Lobo, Pablo; Hernandez Olivares, Francisco; Rangel, C.

2008-01-01

Se presentan los principales resultados de una investigación sobre la fabricación de losas de mortero de cemento común y metacaolín, que incorporan crecientes fracciones volumétricas de polvo de caucho triturado procedente de neumáticos fuera de uso (NFU), hasta superar el 30% en volumen del producto final. Se describen las dosificaciones y las principales propiedades físicas y mecánicas de los productos obtenidos, comparándolas entre sí y con las de losas similares sin polvo de caucho. Se in...

Review on stress corrosion and corrosion fatigue failure of centrifugal compressor impeller

Science.gov (United States)

Sun, Jiao; Chen, Songying; Qu, Yanpeng; Li, Jianfeng

2015-03-01

Corrosion failure, especially stress corrosion cracking and corrosion fatigue, is the main cause of centrifugal compressor impeller failure. And it is concealed and destructive. This paper summarizes the main theories of stress corrosion cracking and corrosion fatigue and its latest developments, and it also points out that existing stress corrosion cracking theories can be reduced to the anodic dissolution (AD), the hydrogen-induced cracking (HIC), and the combined AD and HIC mechanisms. The corrosion behavior and the mechanism of corrosion fatigue in the crack propagation stage are similar to stress corrosion cracking. The effects of stress ratio, loading frequency, and corrosive medium on the corrosion fatigue crack propagation rate are analyzed and summarized. The corrosion behavior and the mechanism of stress corrosion cracking and corrosion fatigue in corrosive environments, which contain sulfide, chlorides, and carbonate, are analyzed. The working environments of the centrifugal compressor impeller show the behavior and the mechanism of stress corrosion cracking and corrosion fatigue in different corrosive environments. The current research methods for centrifugal compressor impeller corrosion failure are analyzed. Physical analysis, numerical simulation, and the fluid-structure interaction method play an increasingly important role in the research on impeller deformation and stress distribution caused by the joint action of aerodynamic load and centrifugal load.

Corrosion Evaluation and Corrosion Control of Steam Generators

Energy Technology Data Exchange (ETDEWEB)

Maeng, W. Y.; Kim, U. C.; Sung, K. W.; Na, J. W.; Lee, Y. H.; Lee, D. H.; Kim, K. M

2008-06-15

Corrosion damage significantly influences the integrity and efficiency of steam generator. Corrosion problems of steam generator are unsolved issues until now even though much effort is made around world. Especially the stress corrosion cracking of heat exchange materials is the first issue to be solved. The corrosion protection method of steam generator is important and urgent for the guarantee of nuclear plant's integrity. The objectives of this study are 1) to evaluate the corrosion properties of steam generator materials, 2) to optimize the water chemistry of steam generator and 3) to develop the corrosion protection method of primary and secondary sides of steam generator. The results will be reflected to the water chemistry guideline for improving the integrity and efficiency of steam generator in domestic power plants.

Corrosion cracking

International Nuclear Information System (INIS)

Goel, V.S.

1985-01-01

This book presents the papers given at a conference on alloy corrosion cracking. Topics considered at the conference included the effect of niobium addition on intergranular stress corrosion cracking, corrosion-fatigue cracking in fossil-fueled-boilers, fracture toughness, fracture modes, hydrogen-induced thresholds, electrochemical and hydrogen permeation studies, the effect of seawater on fatigue crack propagation of wells for offshore structures, the corrosion fatigue of carbon steels in seawater, and stress corrosion cracking and the mechanical strength of alloy 600

Pipeline corrosion prevention by pH stabilization or corrosion inhibitors

Energy Technology Data Exchange (ETDEWEB)

Nyborg, Rolf [Institute for Energy Technology, Oslo (Norway)

2009-07-01

In many offshore oil and gas projects the pipeline costs are a considerable part of the investment and can become prohibitively high if the corrosivity of the fluid necessitates the use of corrosion resistant alloys instead of carbon steel. Development of more robust and reliable methods for internal corrosion control can increase the application range of carbon steel and therefore have a large economic impact. Corrosion control of carbon steel pipelines has traditionally often been managed by the use of corrosion inhibitors. The pH stabilization technique has been successfully used for corrosion control of several large wet gas pipelines in the last years. This method has advantages over film forming corrosion inhibitors when no or little formation water is produced. The use of corrosion inhibitors in multiphase pipelines implies several challenges which are not fully accounted for in traditional corrosion inhibitor testing procedures. Specialized test procedures have been developed to take account for the presence of emulsions dispersions and sand and clay particles in corrosion inhibitor testing. (author)

Underground pipeline corrosion

CERN Document Server

Orazem, Mark

2014-01-01

Underground pipelines transporting liquid petroleum products and natural gas are critical components of civil infrastructure, making corrosion prevention an essential part of asset-protection strategy. Underground Pipeline Corrosion provides a basic understanding of the problems associated with corrosion detection and mitigation, and of the state of the art in corrosion prevention. The topics covered in part one include: basic principles for corrosion in underground pipelines, AC-induced corrosion of underground pipelines, significance of corrosion in onshore oil and gas pipelines, n

en ingeniería de tejido óseo. Fase I: estudios de biocompatibilidad-efectos del hidróxido de calcio

Directory of Open Access Journals (Sweden)

Daniel Gallego

2006-01-01

Full Text Available Actualmente existe una creciente e insatisfecha demanda de substitutos óseos con buen desempeño, tanto desde el punto de vista biológico como mecánico. Basados en las excelentes propiedades mecánico-estructurales del cemento pórtland, se plantea un estudio exploratorio de biocompatibilidad de este material. Se prepararon substratos de cemento pórtland gris tipo I bajo diferentes tratamientos (neutralizado-SN, carbonatado-SC, y no neutralizado-SnN, los cuales fueron luego sometidos a un ensayo de contacto directo con células CHO y HOS durante 24 h. Los substratos se caracterizaron por SEM, y tinciones con fnolftaleía para determinar su pH; mientras que la evaluación del estado del cultivo fue realizada por microscopía de contraste de fase. Los resultados indican que el pH fue mayor para SnN (> 12,0, seguido de SN, y finalmente de los SC (≈ 7,4; de igual manera se observó que la citotoxicidad de los substratos disminuyó en proporción al valor del pH. Se postula que el Ca(OH2 formado durante la hidratación del cemento es el causante del efecto tóxico de éste, y que al agotar las fuentes de Ca(OH2, ya sea por carbonatación o neutralización, se afecta de manera positiva la biocompatibilidad del cemento pórtland.

The external beam facility used to characterize corrosion products in metallic statuettes

International Nuclear Information System (INIS)

Rizzutto, M.A.; Tabacniks, M.H.; Added, N.; Barbosa, M.D.L.; Curado, J.F.; Santos, W.A.; Lima, S.C.; Melo, H.G.; Neiva, A.C.

2005-01-01

To open new possibilities in nuclear applied physics research, mainly for the analysis of art objects in air, an external beam facility was installed at LAMFI (Laboratorio de Analise de Materiais por Feixes Ionicos) of University of Sao Paulo. PIXE measurements were made using an XR-100CR (Si-PIN) X-ray detector pointed to the sample mounted after an approximate 11 mm air path, hence with effective beam energy of 0.9 MeV. This setup was used to characterize the corrosion products of two ethnological metallic statuettes from the African collection of the Museum of Archaeology and Etnology. PIXE analysis of the corrosion free base of one statuette showed that Cu and Zn are the main components of the alloy, while Pb is present in smaller amount. The analysis of some corrosion products showed a Zn:Cu relationship higher than that of the base, evidencing selective corrosion. The main components of the other statuette were Cu and Pb, while S and Zn were found in smaller amounts

Influencia del filler calizo en las propiedades de los morteros a resistencia constante

Directory of Open Access Journals (Sweden)

Hernández, Francisco

1994-03-01

Full Text Available This article studies the effects produced by the lime filler on the Portugal cement used with additions in the production of mortars. The starting point is a Portland cement to which different ratios of lime filler, ranging from 0-50%, are added. The next step consists of preparing mortar specimens using standardized sand as aggregate, curing them up to the age of 28 days when they are put to flexo-tensile and compression tests. The mortar strength is fixed at the age of 28 days, making it coincide with the strength of a pattern cement mortar (cement without additions of the same age. Then the effects of the filler on the slump and the water cement relation are observed for fixed strength.

En este artículo se estudian los efectos producidos por el "filler" calizo en el cemento portland al utilizar este cemento con adiciones, en la fabricación de morteros. Se parte de un cemento portland al que se le añaden proporciones de "filler" calizo desde O hasta el 50%, y se preparan probetas de mortero utilizando como árido arena normalizada, curándose a continuación hasta la edad de 28 días, fecha en la que se someten a rotura por flexotracción y compresión. La resistencia de los morteros se fija a la edad de 28 días, haciéndola coincidir con la de un mortero de cemento patrón (cemento sin adiciones a la misma edad, y se observan, a resistencia fija, los efectos del "filler" sobre el escurrimiento y relación agua/cemento.

Monitoring corrosion rates and localised corrosion in low conductivity water

DEFF Research Database (Denmark)

Hilbert, Lisbeth Rischel

2006-01-01

Monitoring of low corrosion rates and localised corrosion in a media with low conductivity is a challenge. In municipal district heating, quality control may be improved by implementing on-line corrosion monitoring if a suitable technique can be identified to measure both uniform and localised...... corrosion. Electrochemical techniques (LPR, EIS, crevice corrosion current) as well as direct measurement techniques (high-sensitive electrical resistance, weight loss) have been applied in operating plants. Changes in the corrosion processes are best monitored in non-aggressive, low conductivity media...

Dento-osseous anomalies associated to familial adenomatous polyposis mimicking florid cemento-osseous dysplasia.

Science.gov (United States)

Almeida, Fabiana Tolentino; Leite, André Ferreira; de Souza Figueiredo, Paulo Tadeu; Melo, Nilce Santos; Sousa, João Batista; Almeida, Rômulo; Acevedo, Ana Carolina; Silva Guerra, Eliete Neves

2012-12-01

Familial adenomatous polyposis (FAP) is a colorectal cancer syndrome characterized by the development of multiple polyps of the colon and rectum with high risk of malignant transformation. The extraintestinal manifestations such as dento-osseous changes are associated with FAP. This is a case report of a 36-year-old female patient who was referred for dental treatment with the initial diagnosis of florid cemento-osseous dysplasia (FCOD). However, the association of the imaging dento-osseous findings with the medical history confirmed the diagnosis of FAP. The paper illustrates the clinical characteristics and imaging findings associated with FAP, and also discusses misdiagnosis based exclusively on imaging features. Copyright © 2012 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

EVALUATION OF WHITE CEMENT COLOURED WITH ULTRAMARINE BLUE PIGMENT

Directory of Open Access Journals (Sweden)

JUAN CAMILO RESTREPO GUTIÉRREZ

2009-01-01

Full Text Available En el presente trabajo se evalúa el desempeño mecánico del cemento blanco coloreado con pigmento azul ultramar y se explica su desempeño a partir de las modificaciones mineralógicas acaecidas por la sustitución de cemento por pigmento en porcentajes de 5, 10, 15 y 20%. Se fabricaron hormigones y pastas para ser estudiados a 3, 7, 28 y 90 días de curado normal. Se encontró que el pigmento Azul Ultramar al entrar en contacto con el C3A del cemento y el agua, y debido a su contenido de azufre, permite la formación de grandes cantidades de etringita primaria (desordenada y dispersa en la matriz, lo cual se traduce en un incremento de la resistencias mecánicas de los hormigones sustituidos con Azul Ultramar hasta en un 45% a 90 días de curado normal.

Comportamiento a tracción de cementos reforzados con fibras de vidrio

Directory of Open Access Journals (Sweden)

Sánchez Paradela, M. Laura

1991-06-01

Full Text Available Glassfibre Reinforced Cement (GRC is a composite material widely used in the field of building construction. It offers multiple applications due to its high strength as well as fire and corrosoón resistance. However, it degradates with time, affecting its mechanical properties, mainly its ductility, becoming progressively brittle and cracking under low deformations. Therefore, with the aim of predicting the mechanical behaviour of the material, both at short time and long time, a wide experimental program has been carried out, testing fresh material as well as aged material. A high number of tensile tests have been performed, using GRC specimens with different kind of fibres and different manufacturing processes for comparison of results. It must be pointed out that it is the first time that tensile tests of GRC specimens have been carried out in Spain.

El cemento reforzado con fibras de vidrio (GRC es un material compuesto que se viene utilizando ampliamente en el campo de la Construcción. Presenta múltiples aplicaciones debido a sus buenas propiedades resistentes y de protección frente al fuego y la corrosión. Sin embargo, sufre un deterioro con el tiempo, que afecta a sus propiedades mecánicas, principalmente a su ductilidad, volviéndose frágil y agrietándose bajo pequeñas deformaciones. Por tal motivo y con el fin de predecir el comportamiento mecánico del material a corto y a largo plazo, se ha desarrollado un extenso programa experimental, empleando tanto material joven como envejecido. Se han realizado numerosos ensayos de tracción directa, utilizando probetas de GRC con diversos tipos de fibras y empleando distintos métodos de fabricación para una comparación de resultados. Es la primera vez que se realizan ensayos de tracción directa en España sobre probetas de GRC.

Review of corrosion causes and corrosion control in a technical facility

International Nuclear Information System (INIS)

Charng, T.; Lansing, F.

1982-06-01

Causes of corrosion of metals and their alloys are reviewed. The corrosion mechanism is explained by electrochemical reaction theory. The causes and methods of controlling of both physiochemical corrosion and biological corrosion are presented. Factors which influence the rate of corrosion are also discussed

Corrosion/95 conference papers

International Nuclear Information System (INIS)

Anon.

1995-01-01

The papers in this conference represent the latest technological advances in corrosion control and prevention. The following subject areas are covered: cathodic protection in natural waters; materials for fossil fuel combustion and conversion systems; modern problems in atmospheric corrosion; innovative ideas for controlling the decaying infrastructure; deposits and their effects on corrosion in industry; volatile high temperature and non aqueous corrosion inhibitors; corrosion of light-weight and precoated metals for automotive application; refining industry corrosion; corrosion in pulp and paper industry; arctic/cold weather corrosion; materials selection for waste incinerators and associated equipment; corrosion measurement technology; environmental cracking of materials; advancing technology in the coating industry; corrosion in gas treating; green inhibition; recent advances in corrosion control of rail equipment; velocity effects and erosion corrosion in oil and gas production; marine corrosion; corrosion of materials in nuclear systems; underground corrosion control; corrosion in potable and industrial water systems in buildings and its impact on environmental compliance; deposit related boiler tube failures; boiler systems monitoring and control; recent developments and experiences in reactive metals; microbiologically influenced corrosion; corrosion and corrosion control for steel reinforced concrete; international symposium on the use of 12 and 13 Cr stainless steels in oil and gas production environments; subsea corrosion /erosion monitoring in production facilities; fiberglass reinforced pipe and tubulars in oilfield service; corrosion control technology in power transmission and distribution; mechanisms and methods of scale and deposit control; closing the loop -- results oriented cooling system monitoring and control; and minimization of aqueous discharge

Cemento-ossifying fibroma occurring in an elderly patient. A case report and a review of literature.

Science.gov (United States)

Dalghous, Abdulbaset; Alkhabuli, Juma O

2007-06-01

Cemento-ossifying fibromas (COF) are benign lesions affecting the jaws and other craniofacial bones. They commonly affect adults between the third and fourth decade of life. Radiographically, they appear as well-defined unilocular or multilocular intraosseous masses, commonly in the premolar/molar region of the mandible. The lesion is invariably encapsulated and of mixed radiolucent densities. The tumour may grow quite extensively, thus the term aggressive is some times applied. Their clinical, radiographical and histopathological features and those of fibro-osseous lesions are overlapping and may cause confusion in classification, diagnosis, and treatment. The histopathology is composed of fibrous tissues with calcified structures resembling bone or cementum. Surgical enucleation or resection is the treatment of choice. They are insensitive to radiotherapy and recurrences are uncommon. This case report presents a case of COF in 70 years old female patient that was asymptomatic. Clinically, there was an expansion of the buccal plate but not the lingual plate of the right mandible. The covering mucosa was normal and there was no tenderness or paraesthesia. Radiographically, the lesion extends superio-inferiory from the alveolar ridge to the area of inferior dental canal and mesiodistally from the premolar region to the retro-molar area. The lesion was of mixed radiolucent densities. The patient was followed up periodically for 5 years without any treatment. The patient continued to be asymptomatic with minimum changes. Occurrence of cemento-ossifying fibroma in patients over 60 years of age is unusual and had not been reported. The clinical, radiographic, histopathology and literature review are discussed.

Cemento-ossifying fibroma occurring in an elderly patient: A case report and a review of literature

Directory of Open Access Journals (Sweden)

Juma O. Alkhabuli

2007-01-01

Full Text Available Cemento-ossifying fibromas (COF are benign lesions affecting the jaws and other craniofacial bones. They commonly affect adults between the third and fourth decade of life. Radiographically, they appear as well-defined unilocular or multilocular intraosseous masses, commonly in the premolar/molar region of the mandible. The lesion is invariably encapsulated and of mixed radiolucent densities. The tumour may grow quite extensively, thus the term aggressive is some times applied. Their clinical, radiographical and histopathological features and those of fibro-osseous lesions are overlapping and may cause confusion in classification, diagnosis, and treatment.The histopathology is composed of fibrous tissues with calcified structures resembling bone or cementum. Surgical enucleation or resection is the treatment of choice. They are insensitive to radiotherapy and recurrences are uncommon. This case report presents a case of COF in 70 years old female patient that was asymptomatic.Clinically, there was an expansion of the buccal plate but not the lingual plate of the right mandible. The covering mucosa was normal and there was no tenderness or paraesthesia. Radiographically, the lesion extends superio-inferiory from the alveolar ridge to the area of inferior dental canal and mesiodistally from the premolar region to the retro-molar area. The lesion was of mixed radiolucent densities. The patient was followed up periodically for 5 years without any treatment. The patient continued to be asymptomatic with minimum changes. Occurrence of cemento-ossifying fibroma in patients over 60 years of age is unusual and had not been reported. The clinical, radiographic, histopathology and literature review are discussed.

EUROCORR 2007 - The European corrosion congress - Progress by corrosion control. Book of Abstracts

International Nuclear Information System (INIS)

2007-01-01

This book of abstracts contains lectures, workshops and posters which were held on the European Corrosion Congress 2007 in Freiburg (Germany). The main topics of the sessions and posters are: 1. Corrosion and scale inhibition; 2. Corrosion by hot gases and combustion products; 3. Nuclear corrosion; 4. Environment sensitive fracture; 5. Surface Science; 6. Physico-chemical methods of corrosion testing; 7. Marine corrosion; 8. Microbial corrosion; 9. Corrosion of steel in concrete; 10. Corrosion in oil and gas production; 11. Coatings; 12. Corrosion in the refinery industry; 13. Cathodic protection; 14. Automotive Corrosion; 15. Corrosion of polymer materials. The main topics of the workshops are: 1. High temperature corrosion in the chemical, refinery and petrochemical industries; 2. Bio-Tribocorrosion; 3. Stress corrosion cracking in nuclear power plants; 4. Corrosion monitoring in nuclear systems; 5. Cathodic protection for marine and offshore environments; 6. Self-healing properties of new surface treatments; 7. Bio-Tribocorrosion - Cost 533/Eureka-ENIWEP-Meeting; 8. Drinking water systems; 9. Heat exchangers for seawater cooling

Study of sulphate-reducing bacteria corrosion in the weld joint for API X-70 steel

Directory of Open Access Journals (Sweden)

Flores, J. E.

2012-10-01

Full Text Available The corrosion behavior originated by sulfate-reducing bacteria (SRB was studied in two regions of welded API X-70 steel pipeline. The studies were focused on base material (BM and heat affected zone (HAZ, from the internal region of the pipe. SRB were extracted from oil and grown in a Postgate medium. Corrosion was evaluated at 60 °C for times between 5 and 64 days. Potentiodynamic polarization curves, obtained by electrochemical techniques, indicated surface activation at short times. Structural and morphological characterizations were carried out by scanning electron microscopy (SEM and optical microscopy (OM. H₂S concentration and pH were also measured. Results showed an important increase in the corrosion damage up to 20 days, influenced by the SRB activity, which lead to a maximum of H₂S (pH minimum. It was found a localized corrosion attack in the HAZ in a higher quantity compared to BM; and the formation of a thin film on the steel surface, originated by corrosion products and bacterial activity.

El comportamiento ante la corrosión, originada por bacterias sulfato-reductoras (SRB, fue estudiado en dos regiones de un tubo de acero soldado API X-70. Los estudios se enfocaron en el material base (BM y la zona afectada térmicamente (HAZ, en la parte interna del tubo. Las SRB fueron extraídas del petróleo y cultivadas en un medio Postgate. El comportamiento a la corrosión fue evaluado a una temperatura de 60 °C, por periodos comprendidos entre 5 y 64 días. El análisis de las curvas de polarización potenciodinámicas, obtenidas por técnicas electroquímicas, indicó la activación de la superficie para tiempos cortos. La superficie fue caracterizada estructural y morfológicamente mediante microscopia electrónica de barrido (SEM, así como mediante microscopía óptica (OM. La concentración de H₂S y el pH también fueron medidos. Los resultados mostraron un aumento importante de la corrosi

Reducción de cromo hexavalente en cementos usando sulfato ferroso mono y heptahidratado: eficacia y almacenabilidad

OpenAIRE

Valverde, J. L.; Lobato, J.; Fernández, I.; Marijuán, L.; Pérez-Mohedano, S.; Talero, R.

2005-01-01

[ES] Las sustancias que contienen cromo hexavalente están clasificadas en la legislación comunitaria como sustancias carcinogénicas, mutagénicas y sensibilizantes. El cromo hexavalente del cemento potencia la sensibilización y provoca graves reacciones alérgicas que sufren bastante a menudo los trabajadores que lo manipulan habitualmente, ya sea en fábrica o en el sector de la construcción. La dermatitis alérgica o de contacto que produce es muy dolorosa y puede dejar a los trabajadores en es...

Corrosion and stress corrosion cracking in supercritical water

Science.gov (United States)

Was, G. S.; Ampornrat, P.; Gupta, G.; Teysseyre, S.; West, E. A.; Allen, T. R.; Sridharan, K.; Tan, L.; Chen, Y.; Ren, X.; Pister, C.

2007-09-01

Supercritical water (SCW) has attracted increasing attention since SCW boiler power plants were implemented to increase the efficiency of fossil-based power plants. The SCW reactor (SCWR) design has been selected as one of the Generation IV reactor concepts because of its higher thermal efficiency and plant simplification as compared to current light water reactors (LWRs). Reactor operating conditions call for a core coolant temperature between 280 °C and 620 °C at a pressure of 25 MPa and maximum expected neutron damage levels to any replaceable or permanent core component of 15 dpa (thermal reactor design) and 100 dpa (fast reactor design). Irradiation-induced changes in microstructure (swelling, radiation-induced segregation (RIS), hardening, phase stability) and mechanical properties (strength, thermal and irradiation-induced creep, fatigue) are also major concerns. Throughout the core, corrosion, stress corrosion cracking, and the effect of irradiation on these degradation modes are critical issues. This paper reviews the current understanding of the response of candidate materials for SCWR systems, focusing on the corrosion and stress corrosion cracking response, and highlights the design trade-offs associated with certain alloy systems. Ferritic-martensitic steels generally have the best resistance to stress corrosion cracking, but suffer from the worst oxidation. Austenitic stainless steels and Ni-base alloys have better oxidation resistance but are more susceptible to stress corrosion cracking. The promise of grain boundary engineering and surface modification in addressing corrosion and stress corrosion cracking performance is discussed.

Corrosion/96 conference papers

International Nuclear Information System (INIS)

Anon.

1996-01-01

Topics covered by this conference include: cathodic protection in natural waters; cleaning and repassivation of building HVAC systems; worldwide opportunities in flue gas desulfurization; advancements in materials technology for use in oil and gas service; fossil fuel combustion and conversion; technology of corrosion inhibitors; computers in corrosion control--modeling and information processing; recent experiences and advances of austenitic alloys; managing corrosion with plastics; corrosion measurement technology; corrosion inhibitors for concrete; refining industry; advances in corrosion control for rail and tank trailer equipment; CO 2 corrosion--mechanisms and control; microbiologically influenced corrosion; corrosion in nuclear systems; role of corrosion in boiler failures; effects of water reuse on monitoring and control technology in cooling water applications; methods and mechanisms of scale and deposit control; corrosion detection in petroleum production lines; underground corrosion control; environmental cracking--relating laboratory results and field behavior; corrosion control in reinforced concrete structures; corrosion and its control in aerospace and military hardware; injection and process addition facilities; progress reports on the results of reinspection of deaerators inspected or repaired per RP0590 criteria; near 100% volume solids coating technology and application methods; materials performance in high temperature environments containing halides; impact of toxicity studies on use of corrosion/scale inhibitors; mineral scale deposit control in oilfield related operations; corrosion in gas treating; marine corrosion; cold climate corrosion; corrosion in the pulp and paper industry; gaseous chlorine alternatives in cooling water systems; practical applications of ozone in recirculating cooling water systems; and water reuse in industry. Over 400 papers from this conference have been processed separately for inclusion on the data base

Corrosion/94 conference papers

International Nuclear Information System (INIS)

Anon.

1994-01-01

The approximately 500 papers from this conference are divided into the following sections: Rail transit systems--stray current corrosion problems and control; Total quality in the coatings industry; Deterioration mechanisms of alloys at high temperatures--prevention and remediation; Research needs and new developments in oxygen scavengers; Computers in corrosion control--knowledge based system; Corrosion and corrosivity sensors; Corrosion and corrosion control of steel reinforced concrete structures; Microbiologically influenced corrosion; Practical applications in mitigating CO 2 corrosion; Mineral scale deposit control in oilfield-related operations; Corrosion of materials in nuclear systems; Testing nonmetallics for life prediction; Refinery industry corrosion; Underground corrosion control; Mechanisms and applications of deposit and scale control additives; Corrosion in power transmission and distribution systems; Corrosion inhibitor testing and field application in oil and gas systems; Decontamination technology; Ozone in cooling water applications, testing, and mechanisms; Corrosion of water and sewage treatment, collection, and distribution systems; Environmental cracking of materials; Metallurgy of oil and gas field equipment; Corrosion measurement technology; Duplex stainless steels in the chemical process industries; Corrosion in the pulp and paper industry; Advances in cooling water treatment; Marine corrosion; Performance of materials in environments applicable to fossil energy systems; Environmental degradation of and methods of protection for military and aerospace materials; Rail equipment corrosion; Cathodic protection in natural waters; Characterization of air pollution control system environments; and Deposit-related problems in industrial boilers. Papers have been processed separately for inclusion on the data base

Mandibular Actinomyces osteomyelitis complicating florid cemento-osseous dysplasia: case report.

Science.gov (United States)

Smith, Miller H; Harms, Paul W; Newton, Duane W; Lebar, Bill; Edwards, Sean P; Aronoff, David M

2011-07-21

Apart from neoplastic processes, chronic disfiguring and destructive diseases of the mandible are uncommon. We report, perhaps for the first time, the simultaneous occurrence of two such conditions in one patient, in a case that emphasizes the importance of bone biopsy in establishing the correct diagnosis. Florid cemento-osseous dysplasia (FCOD) is a chronic, disfiguring condition of the maxillofacial region. This relatively benign disease is primarily observed in middle-aged women of African ancestry. Cervicofacial actinomycosis is an uncommon and progressive infection caused by bacilli of the Actinomyces genus that typically involves intraoral soft tissues but may also involve bone. The accurate diagnosis of actinomycosis is critical for successful treatment. A diagnosis of osteomyelitis caused by Actinomyces bacteria was diagnosed by bone biopsy in a 53 year-old African-American woman with a longstanding history of FCOD after she presented with a new draining ulcer overlying the mandible. Clinicians should be aware of the possibility of actinomycosis arising in the setting of FCOD, and the importance of bone biopsy and cultures in arriving at a definitive and timely diagnosis.

Estudio teórico y experimental sobre los morteros para muros resistentes de fábrica de ladrillo para la actualización de la Norma Básica MV 201-1972

Directory of Open Access Journals (Sweden)

Monterde Comba, Guillermo J.

1984-12-01

Full Text Available This theoretical and experimental study on cement or lime and cement mortars brings up to date the contents of Chapter 3: MORTARS, of Norm MV 201-1972 "Resistant brick-work walls" which lost its validity when disappeared portland cement P-250, substituted by portland cement PA-350 with active additions, prescribed in the new Standard RC-75 "Standard of general technical prescriptions for cements acceptance" being obligatory its fulfilment.

El presente estudio teórico y experimental sobre morteros, de cemento o de cal y cemento, constituye la puesta al día del contenido del Capítulo 3º MORTEROS, de la Norma MV 201-1972 "Muros resistentes de fábrica de ladrillo'', que perdió su vigencia con la desaparición del cemento portland P-250, sustituido por el cemento portland PA-350 con adiciones activas prescrito en el nuevo Pliego RC-75 "Pliego de prescripciones técnicas generales para la recepción de cementos" de obligado cumplimiento.

Corrosion technology. V. 1

International Nuclear Information System (INIS)

Khan, I.H.

1989-01-01

This book has been produced for dissemination of information on corrosion technology, corrosion hazards and its control. Chapter one of this book presents an overall view of the subject and chapter 2-5 deals with electrochemical basics, types of corrosion, pourbaix diagrams and form of corrosion. The author explains polarization/kinetics of corrosion, passivity, aqueous corrosion and corrosion testing and monitoring in 6-11 chapters. The author hopes it will provide incentive to all those interested in the corrosion technology. (A.B.)

Aportaciones al estudio reológico de pastas y morteros de cemento portland

Directory of Open Access Journals (Sweden)

Miranda, J.

2000-03-01

ómetro más adecuado para caracterizar este tipo de muestras, considerando la dificultad que conlleva el estudio reológico de suspensiones de concentración elevada que tienden a desarrollar fenómenos de deslizamiento en las paredes del sistema sensor. Entre los equipos con sensor placa-placa, con cilindros coaxiles y con agitador de cinta helicoidal, fueron desechados los primeros debido a la alta relación diámetro de partícula/hueco de medida que presentan y que hace que las propiedades viscosas sean escasamente repetitivas, mientras que el último aparato no presenta este problema, por lo que se optó por su utilización para la obtención de las propiedades reológicas de las muestras en estudio. En segundo lugar, se ha tratado de describir el comportamiento viscoso de distintas pastas y morteros con diferentes agregados y relaciones agua/cemento. Para ello se realizaron barridos de velocidad de agitación y ensayos a velocidad constante, relacionando la evolución de la viscosidad con los períodos del fraguado. El análisis del comportamiento reológico se ve afectado por el hecho de aplicar una agitación que provoca la ruptura de un sistema que tiende a estructurarse durante el proceso de fraguado, por lo que esta especificidad en función del tiempo, unida a la heterogeneidad de las muestras, dificulta la obtención de resultados con una buena repetibilidad.

A review on pipeline corrosion, in-line inspection (ILI), and corrosion growth rate models

International Nuclear Information System (INIS)

Vanaei, H.R.; Eslami, A.; Egbewande, A.

2017-01-01

Pipelines are the very important energy transmission systems. Over time, pipelines can corrode. While corrosion could be detected by in-line inspection (ILI) tools, corrosion growth rate prediction in pipelines is usually done through corrosion rate models. For pipeline integrity management and planning selecting the proper corrosion ILI tool and also corrosion growth rate model is important and can lead to significant savings and safer pipe operation. In this paper common forms of pipeline corrosion, state of the art ILI tools, and also corrosion growth rate models are reviewed. The common forms of pipeline corrosion introduced in this paper are Uniform/General Corrosion, Pitting Corrosion, Cavitation and Erosion Corrosion, Stray Current Corrosion, Micro-Bacterial Influenced Corrosion (MIC). The ILI corrosion detection tools assessed in this study are Magnetic Flux Leakage (MFL), Circumferential MFL, Tri-axial MFL, and Ultrasonic Wall Measurement (UT). The corrosion growth rate models considered in this study are single-value corrosion rate model, linear corrosion growth rate model, non-linear corrosion growth rate model, Monte-Carlo method, Markov model, TD-GEVD, TI-GEVD model, Gamma Process, and BMWD model. Strengths and limitations of ILI detection tools, and also corrosion predictive models with some practical examples are discussed. This paper could be useful for those whom are supporting pipeline integrity management and planning. - Highlights: • Different forms of pipeline corrosion are explained. • Common In-Line Inspection (ILI) tools and corrosion growth rate models are introduced. • Strength and limitations of corrosion growth rate models/ILI tools are discussed. • For pipeline integrity management programs using more than one corrosion growth rate model/ILI tool is suggested.

Erosion and erosion-corrosion

International Nuclear Information System (INIS)

Isomoto, Yoshinori

2008-01-01

It is very difficult to interpret the technical term of erosion-corrosion' which is sometimes encountered in piping systems of power plants, because of complicated mechanisms and several confusing definitions of erosion-corrosion phenomena. 'FAC (flow accelerated corrosion)' is recently introduced as wall thinning of materials in power plant systems, as a representative of 'erosion-corrosion'. FAC is, however, not necessarily well understood and compared with erosion-corrosion. This paper describes firstly the origin, definition and fundamental understandings of erosion and erosion-corrosion, in order to reconsider and reconfirm the phenomena of erosion, erosion-corrosion and FAC. Next, typical mapping of erosion, corrosion, erosion-corrosion and FAC are introduced in flow velocity and environmental corrosiveness axes. The concept of damage rate in erosion-corrosion is finally discussed, connecting dissolution rate, mass transfer of metal ions in a metal oxide film and film growth. (author)

Comportamiento de la corrosión de aleaciones de magnesio AZ31-B en ambiente marino, modificadas por el proceso de fricción-agitación Corrosion behavior in marine environment of magnesium alloy AZ31-B welded by friction-agitation process

Directory of Open Access Journals (Sweden)

Willian Aperador Chaparro

2012-04-01

Full Text Available En el presente artículo se estudia el comportamiento de la corrosión de la aleación de magnesio AZ31-B en ambiente marino simulado, modificada mediante el proceso de fricción-agitación (PFA, con el fin de determinar el efecto de las variables del proceso, velocidad de rotación y velocidad de avance. Se llevaron a cabo análisis mediante espectroscopia de impedancia electroquímica y curvas de polarización potencio-dinámicas (Tafel. Adicionalmente, se determinó la microestructura en las zonas del cordón de soldadura a través de metalografía óptica. Finalmente, se analizaron los productos de corrosión formados en la superficie de las muestras por medio del microscopio electrónico de barrido (SEM equipado con el analizador químico por EDS. Se observó que una relación de velocidad de avance/velocidad de rotación mayor produce menor velocidad de corrosión y con ello mayor resistencia a la corrosión en medios salinos, al parecer relacionados con el gran tamaño de grano en la zona agitada, que corresponde a más entrada de calor.The corrosion behavior of AZ31B magnesium alloy modified by friction stir processing (FSP was studied in simulated marine environment, in order to determine the effect of process variables rotation speed and travel speed. The corrosion analysis was carried upon by means of electrochemical impedance spectroscopy and potentiodynamic polarization curves (Tafel, metallographic analysis of the welded zones was done by optical microscopy and the chemical analysis of the corrosion products were done by using scanning electron microscope (SEM, equipped with EDS analyzer. It was observed that the increase of the rate rotation speed/travel speed of the process produces a decrease in the corrosion rate and the corresponding increase of the corrosion resistance in marine environment, apparently related to the higher grain size found in the stir zone, corresponding to a higher heat input.

Accelerated Corrosion Testing

Science.gov (United States)

1982-12-01

Treaty Organization, Brussels, 1971), p. 449. 14. D. 0. Sprowls, T. J. Summerson, G. M. Ugianski, S. G. Epstein, and H. L. Craig , Jr., in Stress...National Association of Corrosion Engineers Houston, TX, 1972). 22. H. L. Craig , Jr. (ed.), Stress Corrosion-New Approaches, ASTM-STP- 610 (American...62. M. Hishida and H. Nakada, Corrosion 33 (11) 403 (1977). b3. D. C. Deegan and B. E. Wilde, Corrosion 34 (6), 19 (1978). 64. S. Orman, Corrosion Sci

Ladrillos de suelo-cemento: mampuesto tradicional en base a un material sostenible

Directory of Open Access Journals (Sweden)

P. Gatani, Mariana

2000-04-01

Full Text Available Like a basic construction material, the soil has been used since the distant past. In our days, we know very few about country constructors, probably because of our ignorance concerning the traditional materials they have used. Inspite of the existence of a lot of experiences and informations concerning this matter, the antecedents about the development of the materials comming from the mixture of soil, lime and/or concrete, have not been spread enough.Como base de construcción, la tierra es empleada desde tiempos remotos. En nuestro medio, no ha trascendido la esfera de pequeños grupos organizados o autoconstructores rurales, sin duda alguna, imputable al desconocimiento de los materiales utilizados tradicionalmente. Pese a que existe un cúmulo de experiencias y de datos experimentales, los antecedentes sobre desarrollo de materiales resultantes de mezclas de tierra, cal y/o cemento no han sido divulgados suficientemente.

Aplicación de la espectroscopia infrarroja al estudio de cemento aluminoso

Directory of Open Access Journals (Sweden)

Fernández-Carrasco, Lucía

1996-03-01

Full Text Available Mineralogical components of hydrated high alumina cement were studied by means of infrared absorption spectroscopy. The same technique was also used to analyze the samples obtained from beams that had been made with high alumina concrete. The article points up the importance of this technique as complementary to others used more habitually in the characterization of these compounds.

Se han estudiado los componentes mineralógicos del cemento aluminoso hidratado a través de la técnica de espectroscopia de absorción infrarroja. Se ha realizado, también con esta técnica, un análisis de las muestras que se han obtenido de viguetas que fueron fabricadas con hormigón aluminoso. Se destaca la importancia de esta técnica como complementaria de otras más habitualmente utilizadas en la caracterización de estos compuestos.

Concrete cover cracking with reinforcement corrosion of RC beam during chloride-induced corrosion process

International Nuclear Information System (INIS)

Zhang Ruijin; Castel, Arnaud; Francois, Raoul

2010-01-01

This paper deals with the evolution of the corrosion pattern based on two beams corroded by 14 years (beam B1CL1) and 23 years (beam B2CL1) of conservation in a chloride environment. The experimental results indicate that, at the cracking initiation stage and the first stage of cracking propagation, localized corrosion due to chloride ingress is the predominant corrosion pattern and pitting corrosion is the main factor that influences the cracking process. As corrosion cracking increases, general corrosion develops rapidly and gradually becomes predominant in the second stage of cracking propagation. A comparison between existing models and experimental results illustrates that, although Vidal et al.'s model can better predict the reinforcement corrosion of beam B1CL1 under localized corrosion, it cannot predict the corrosion of beam B2CL1 under general corrosion. Also, Rodriguez's model, derived from the general corrosion due to electrically accelerated corrosion experiments, cannot match natural chloride corrosion irrespective of whether corrosion is localized or general. Thus, for natural general corrosion in the second stage of cracking propagation, a new model based on the parameter of average steel cross-section loss is put forward to predict steel corrosion from corrosion cracking.

Durability of reinforced adobe exposed to chloride ions

Directory of Open Access Journals (Sweden)

Giménez, A.

2006-12-01

Full Text Available One of the primary shortcomings of adobe, a dried mudblock stabilized with sisal hemp and cement widely used across all of Latin America, is its dimensional instability when exposed to water or aggressive environments. The present paper evaluates the electrochemical performance of reinforced adobe block after 1,000 days of exposure to a simulated marine environment. The specimens used were adobe blocks internally reinforced with 3/8-inch steel bars. The specimens were watered every two weeks: one group with potable water to simulate a natural urban environment and the other with a 3% sodium chloride solution to simulate a marine environment.Chloride penetration in powder extracted from the specimens was determined using the Mohr method. Electrochemical measurements included Gecor 6 electric potential(Eº and corrosion intensity (icorr readings. The final conclusion drawn from an analysis of the results was that in all cases the amount of free chlorides present sufficed to depassivate reinforcing steel and that the system component providing the most effective protection was the rough casting mortar. Consequently, this type of adobe mixes is not recommended for use in marine or industrial environments.La tierra-cemento-sisal es un material cuyo uso se encuentra muy difundido en toda Latinoamérica, entre sus principales limitaciones está la inestabilidad volumétrica ante el agua y ambientes agresivos. Por tal motivo, en este trabajo se evaluó el comportamiento electroquímico de bloques de tierra-cemento-sisal armado expuestos durante 1.000 días a un ambiente marino simulado. Las probetas utilizadas fueron bloques de tierra-cemento-sisal incorporándole internamente barras de acero de 3/8 de pulg. Las probetas se sometieron a un rociado quincenal: las de ambiente natural urbano con agua potable y las de ambiente marino simulado con una solución al 3% de cloruro de sodio. La penetración de cloruros se determinó extrayendo polvillo y

Pitting corrosion behaviour study of aluminium matrix composites (A3xx.x/SiCp); Estudio del comportamiento a la corrosion por picadura de materiales compuestos de matriz de aluminio (A3xx.x/SiCp)

Energy Technology Data Exchange (ETDEWEB)

Pardo, A.; Merino, M. C.; Merino, S.; Lopez, M. D.; Viejo, F.; Carboneras, M.; Arrabal, R.

2004-07-01

The influence of the SiCp proportion on the pitting corrosion of A3xx.x/SiC/xxp composites was studies by means of potenciodinamic polarization and double cyclic polarization in saline environment at 25 degree centigree A360/SiC/xxp matrix does not contain copper, whereas the A380/SiC/xxp matric contains 1,39-1,44 wt %Cu. The kinetic study was carried out by gravimetric measurements. The nature of corrosion products was analysed by low angle XRD and Scanning Electron Microscopy (SEM). The corrosion is due to nucleation and growth of Al{sub 2}O{sub 3}-3H{sub 2}O on the material surface. The corrosion increases with the reinforcement proportion, chloride concentration and copper content. (Author) 10 refs.

Humid-air and aqueous corrosion models for corrosion-allowance barrier material

International Nuclear Information System (INIS)

Lee, J.H.; Atkins, J.E.; Andrews, R.W.

1995-01-01

Humid-air and aqueous general and pitting corrosion models (including their uncertainties) for the carbon steel outer containment barrier were developed using the corrosion data from literature for a suite of cast irons and carbon steels which have similar corrosion behaviors to the outer barrier material. The corrosion data include the potential effects of various chemical species present in the testing environments. The atmospheric corrosion data also embed any effects of cyclic wetting and drying and salts that may form on the corroding specimen surface. The humid-air and aqueous general corrosion models are consistent in that the predicted humid-air general corrosion rates at relative humidities between 85 and 100% RH are close to the predicted aqueous general corrosion rates. Using the expected values of the model parameters, the model predicts that aqueous pitting corrosion is the most likely failure mode for the carbon steel outer barrier, and an earliest failure (or initial pit penetration) of the 100-mm thick barrier may occur as early as about 500 years if it is exposed continuously to an aqueous condition at between 60 and 70 degrees C

Quantitative measures of corrosion and prevention: application to corrosion in agriculture

NARCIS (Netherlands)

Schouten, J.C.; Gellings, P.J.

1987-01-01

The corrosion protection factor (c.p.f.) and the corrosion condition (c.c.) are simple instruments for the study and evaluation of the contribution and efficiency of several methods of corrosion prevention and control. The application of c.p.f. and c.c. to corrosion and prevention in agriculture in

Evaluation of corrosive behavior of SAE 5155 by corrosion environment

International Nuclear Information System (INIS)

An, Jae Pil; Park, Keyung Dong

2005-01-01

In this study, the influence of shot peening and corrosive condition for corrosion property was investigated on immersed in 3.5% NaCl, 10% HNO 3 + 3% HF, 6% FeCl 3 . The immersion test was performed on two kinds of specimen. The immersion periods was performed 30days. Corrosion potential, weight loss were investigated from experimental results. From test results, the effect of shot peening on the corrosion was evaluated

Synergy effect of naphthenic acid corrosion and sulfur corrosion in crude oil distillation unit

Science.gov (United States)

Huang, B. S.; Yin, W. F.; Sang, D. H.; Jiang, Z. Y.

2012-10-01

The synergy effect of naphthenic acid corrosion and sulfur corrosion at high temperature in crude oil distillation unit was studied using Q235 carbon-manganese steel and 316 stainless steel. The corrosion of Q235 and 316 in corrosion media containing sulfur and/or naphthenic acid at 280 °C was investigated by weight loss, scanning electron microscope (SEM), EDS and X-ray diffractometer (XRD) analysis. The results showed that in corrosion media containing only sulfur, the corrosion rate of Q235 and 316 first increased and then decreased with the increase of sulfur content. In corrosion media containing naphthenic acid and sulfur, with the variations of acid value or sulfur content, the synergy effect of naphthenic acid corrosion and sulfur corrosion has a great influence on the corrosion rate of Q235 and 316. It was indicated that the sulfur accelerated naphthenic acid corrosion below a certain sulfur content but prevented naphthenic acid corrosion above that. The corrosion products on two steels after exposure to corrosion media were investigated. The stable Cr5S8 phases detected in the corrosion products film of 316 were considered as the reason why 316 has greater corrosion resistance to that of Q235.

Degradation of aged plants by corrosion: 'Long cell action' in unresolved corrosion issues

International Nuclear Information System (INIS)

Saji, Genn

2009-01-01

In a series of previously published papers the author has identified that 'long cell action' corrosion plays a pivotal role in practically all unresolved corrosion issues for all types of nuclear power plants (e.g. PWR/VVER, BWR/RBMK and CANDU). Some of these unresolved issues are IGSCC, PWSCC, AOA and FAC (erosion-corrosion). In conventional corrosion science it is well established that 'long cell action' can seriously accelerate or suppress the local cell corrosion activities. Although long cell action is another fundamental mechanism of corrosion, especially in a 'soil corrosion' arena, potential involvement of this corrosion process has never been studied in nuclear and fossil power plants as far as the author has been able to establish. The author believes that the omission of this basic corrosion mechanism is the root cause of practically all un-resolved corrosion issues. In this paper, the author further elaborated on his assessment to other key corrosion issues, e.g. steam generator and turbine corrosion issues, while briefly summarizing previous discussions for completeness purposes, as well as introducing additional experimental and theoretical evidence of this basic corrosion mechanism. Due to the importance of this potential mechanism the author is calling for institutional review activities and further verification experiments in the form of a joint international project.

Applied methods for mitigation of damage by stress corrosion in BWR type reactors; Metodos aplicados para la mitigacion del dano por corrosion bajo esfuerzo en reactores BWR

Energy Technology Data Exchange (ETDEWEB)

Hernandez C, R.; Diaz S, A.; Gachuz M, M.; Arganis J, C. [Instituto Nacional de Investigaciones Nucleares, Gerencia de Ciencia de Materiales, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

1998-07-01

The Boiling Water nuclear Reactors (BWR) have presented stress corrosion problems, mainly in components and pipes of the primary system, provoking negative impacts in the performance of energy generator plants, as well as the increasing in the radiation exposure to personnel involucred. This problem has caused development of research programs, which are guided to find solution alternatives for the phenomena control. Among results of greater relevance the control for the reactor water chemistry stands out particularly in the impurities concentration and oxidation of radiolysis products; as well as the supervision in the materials selection and the stresses levels reduction. The present work presents the methods which can be applied to diminish the problems of stress corrosion in BWR reactors. (Author)

Corrosion Testing Facility

Data.gov (United States)

Federal Laboratory Consortium — The Corrosion Testing Facility is part of the Army Corrosion Office (ACO). It is a fully functional atmospheric exposure site, called the Corrosion Instrumented Test...

Synergy effect of naphthenic acid corrosion and sulfur corrosion in crude oil distillation unit

Energy Technology Data Exchange (ETDEWEB)

Huang, B.S., E-mail: yinwenfeng2010@163.com [College of Materials Science and Engineering, Southwest Petroleum University, Sichuan, Chengdu, 610500 (China); Yin, W.F. [College of Mechatronic Engineering, Southwest Petroleum University, Sichuan, Chengdu, 610500 (China); Sang, D.H. [Sheng Li Construction Group International Engineering Department, Shandong, Dongying, 257000 (China); Jiang, Z.Y. [College of Materials Science and Engineering, Southwest Petroleum University, Sichuan, Chengdu, 610500 (China)

2012-10-15

Highlights: Black-Right-Pointing-Pointer The corrosion of a carbon-manganese steel and a stainless steel in sulfur and/or naphthenic acid media was investigated. Black-Right-Pointing-Pointer The corrosion rate of the carbon-manganese steel increased with the increase of the acid value and sulfur content. Black-Right-Pointing-Pointer The critical values of the concentration of sulfur and acid for corrosion rate of the stainless steel were ascertained respectively. Black-Right-Pointing-Pointer The stainless steel is superior to the carbon-manganese steel in corrosion resistance because of the presence of stable Cr{sub 5}S{sub 8} phases. - Abstract: The synergy effect of naphthenic acid corrosion and sulfur corrosion at high temperature in crude oil distillation unit was studied using Q235 carbon-manganese steel and 316 stainless steel. The corrosion of Q235 and 316 in corrosion media containing sulfur and/or naphthenic acid at 280 Degree-Sign C was investigated by weight loss, scanning electron microscope (SEM), EDS and X-ray diffractometer (XRD) analysis. The results showed that in corrosion media containing only sulfur, the corrosion rate of Q235 and 316 first increased and then decreased with the increase of sulfur content. In corrosion media containing naphthenic acid and sulfur, with the variations of acid value or sulfur content, the synergy effect of naphthenic acid corrosion and sulfur corrosion has a great influence on the corrosion rate of Q235 and 316. It was indicated that the sulfur accelerated naphthenic acid corrosion below a certain sulfur content but prevented naphthenic acid corrosion above that. The corrosion products on two steels after exposure to corrosion media were investigated. The stable Cr{sub 5}S{sub 8} phases detected in the corrosion products film of 316 were considered as the reason why 316 has greater corrosion resistance to that of Q235.

Maxillo-Mandibular Cemento-ossifying Fibroma: A Rare Case Report.

Science.gov (United States)

Peravali, Ranjit Kumar; Bhat, H Hari Kishore; Reddy, Sreenatha

2015-03-01

Cemento-ossifying fibroma (COF) is a benign fibro osseous lesion of the jaws which has been described as a demarcated or rarely encapsulated neoplasm consisting of fibrous tissue and varying amounts of mineralized material resembling bone and/or cementum (Dinkar et al. in IJDA 2(4):45-47, 2010). Majority of lesions occur in the mandible and only few cases of COFs of the maxillary sinus and bilateral COFs of the mandible have been reported in literature (Dinkar et al. in IJDA 2(4):45-47, 2010; Tamiolakis et al. in Acta Stomatol Croat 39(3):319-321, 2005; Hamner et al. in Oral Surg Oral Med Oral Pathol 26(4):579-587, 1968; Gunaseelan et al. in Oral Med Oral Pathol Oral Radiol Endod 104:e21-e25, 2007). These lesions have a very low recurrence rate (Ertug et al. in Quintessence Int 35(10):808-810, 2004) and are generally treated by enucleation. In this paper we present a rare case of COF occurring in both the maxilla and mandible of the same patient. Only one such case (Takeda and Fujioka in Int J Oral Maxillofac Surg 16(3):368-371, 1987) has been reported in literature so far.

Predicting the drying shrinkage behavior of high strength portland cement mortar under the combined influence of fine aggregate and steel micro fiber; Predicción del comportamiento de retracción por secado de morteros de cemento Pórtland de alta resistencia bajo la influencia combinada de árido fino y micro fibra de acero.

Energy Technology Data Exchange (ETDEWEB)

Li, Zhengqi

2017-07-01

The workability, 28-day compressive strength and free drying shrinkage of a very high strength (121-142 MPa) steel micro fiber reinforced portland cement mortar were studied under a combined influence of fine aggregate content and fiber content. The test results showed that an increase in the fine aggregate content resulted in decreases in the workability, 28-day compressive strength and drying shrinkage of mortar at a fixed fiber content. An increase in the fiber content resulted in decreases in the workability and drying shrinkage of mortar, but an increase in the 28-day compressive strength of mortar at a fixed fine aggregate content. The modified Gardner model most accurately predicted the drying shrinkage development of the high strength mortars, followed by the Ross model and the ACI 209R-92 model. The Gardner model gave the least accurate prediction for it was developed based on a database of normal strength concrete. [Spanish] Se ha estudiado la trabajabilidad, resistencia a la compresión (28 días) y la retracción al secado de morteros de cemento Pórtland de muy alta resistencia (121-142 MPa) reforzados con micro fibra de acero, con la influencia combinada de contenido de árido fino y de micro fibra de acero. El aumento en el contenido de árido fino resultó en la disminución de la trabajabilidad, resistencia a la compresión y la retracción por secado de los morteros con un contenido de fibra específico. El aumento en el contenido de fibra dio lugar a la disminución de la trabajabilidad y la retracción por secado, y a un aumento en la resistencia a la compresión a 28 días en morteros con un contenido específico de á rido fino. El modelo modificado de Gardner predijo con más precisión la retracción por secado de mortero de alta resistencia, seguido por el modelo de Ross y el modelo ACI 209R-92. El modelo de Gardner dio la predicción menos exacta debido al hecho de que se desarrolló sobre bases de datos de hormigones de resistencia normal.

Erosion-corrosion

International Nuclear Information System (INIS)

Aghili, B.

1999-05-01

A literature study on erosion-corrosion of pipings in the nuclear industry was performed. Occurred incidents are reviewed, and the mechanism driving the erosion-corrosion is described. Factors that influence the effect in negative or positive direction are treated, as well as programs for control and inspection. Finally, examples of failures from databases on erosion-corrosion are given in an attachment

Corrosion behaviors and effects of corrosion products of plasma electrolytic oxidation coated AZ31 magnesium alloy under the salt spray corrosion test

International Nuclear Information System (INIS)

Wang, Yan; Huang, Zhiquan; Yan, Qin; Liu, Chen; Liu, Peng; Zhang, Yi; Guo, Changhong; Jiang, Guirong; Shen, Dejiu

2016-01-01

Highlights: • Corrosion behaviors of a PEO coating was investigated after the salt spray test. • Corrosion products have significant effects on corrosion behaviors of the coating. • An electrochemical corrosion model is proposed. - Abstract: The effects of corrosion products on corrosion behaviors of AZ31 magnesium alloy with a plasma electrolytic oxidation (PEO) coating were investigated under the salt spray corrosion test (SSCT). The surface morphology, cross-sectional microstructure, chemical and phase compositions of the PEO coating were determined using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction analysis (XRD), respectively. Further, the corrosion process of the samples under the SSCT was examined in a non-aqueous electrolyte (methanol) using electrochemical impedance spectroscopy (EIS) coupled with equivalent circuit. The results show that the inner layer of the coating was destroyed firstly and the corrosion products have significant effects on the corrosion behaviors of the coating. The results above are discussed and an electrochemical corrosion model is proposed in the paper.

Corrosion behaviors and effects of corrosion products of plasma electrolytic oxidation coated AZ31 magnesium alloy under the salt spray corrosion test

Energy Technology Data Exchange (ETDEWEB)

Wang, Yan; Huang, Zhiquan; Yan, Qin; Liu, Chen; Liu, Peng; Zhang, Yi [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Guo, Changhong; Jiang, Guirong [College of Mechanical Engineering, Yanshan University, Qinhuangdao 066004 (China); Shen, Dejiu, E-mail: DejiuShen@163.com [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China)

2016-08-15

Highlights: • Corrosion behaviors of a PEO coating was investigated after the salt spray test. • Corrosion products have significant effects on corrosion behaviors of the coating. • An electrochemical corrosion model is proposed. - Abstract: The effects of corrosion products on corrosion behaviors of AZ31 magnesium alloy with a plasma electrolytic oxidation (PEO) coating were investigated under the salt spray corrosion test (SSCT). The surface morphology, cross-sectional microstructure, chemical and phase compositions of the PEO coating were determined using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction analysis (XRD), respectively. Further, the corrosion process of the samples under the SSCT was examined in a non-aqueous electrolyte (methanol) using electrochemical impedance spectroscopy (EIS) coupled with equivalent circuit. The results show that the inner layer of the coating was destroyed firstly and the corrosion products have significant effects on the corrosion behaviors of the coating. The results above are discussed and an electrochemical corrosion model is proposed in the paper.

Stress corrosion and corrosion fatigue crack growth monitoring in metals

International Nuclear Information System (INIS)

Senadheera, T.; Shipilov, S.A.

2003-01-01

Environmentally assisted cracking (including stress corrosion cracking and corrosion fatigue) is one of the major causes for materials failure in a wide variety of industries. It is extremely important to understand the mechanism(s) of environmentally assisted crack propagation in structural materials so as to choose correctly from among the various possibilities-alloying elements, heat treatment of steels, parameters of cathodic protection, and inhibitors-to prevent in-service failures due to stress corrosion cracking and corrosion fatigue. An important step towards understanding the mechanism of environmentally assisted crack propagation is designing a testing machine for crack growth monitoring and that simultaneously provides measurement of electrochemical parameters. In the present paper, a direct current (DC) potential drop method for monitoring crack propagation in metals and a testing machine that uses this method and allows for measuring electrochemical parameters during stress corrosion and corrosion fatigue crack growth are described. (author)

ANÁLISIS DE CORROSIÓN EN DUCTOS DE CONDUCCIÓN DE GASES EN UNA PLANTA DE CLINKER CORROSION ANALYSIS IN GAS CONDUCTION DUCTS IN A CLINKER PLANT

Directory of Open Access Journals (Sweden)

Alex Humberto Restrepo Carvajal

2009-04-01

Full Text Available En este trabajo se presentan los resultados de un estudio detallado de las causas del deterioro observado en ductos metálicos de una planta productora de cemento. Para el análisis, se inició con una minuciosa inspección visual, tomando muestras de sustratos, productos de corrosión y gases de proceso. Al mismo tiempo se realizaron medidas de potencial de estructura, espesores de pared y temperaturas de superficies. Para la evaluación de la agresividad del ambiente se instalaron captadores de contaminantes (cloruros, sulfatos y óxidos de nitrógeno. Las muestras recolectadas se analizaron por medio de microscopia óptica y electrónica de barrido, espectroscopia EDS, difracción de rayos X, espectroscopia infrarroja y cromatografía iónica. Los gases se analizaron insitu siguiendo el procedimiento EPA-2. Los resultados para las superficies externas indican una atmósfera con agresividad C3 según la norma ISO 9223, observando influencia de la alta temperatura, largos periodos de humectación, material particulado y errores en la selección del sistema de protección. Las capas de productos al exterior son uniformes, compactas y son compuestas principalmente por hematita. Al interior de los ductos se presentan procesos de sulfurización y oxidación; el ataque por azufre es localizado y genera perforación de las paredes metálicas. Los productos encontrados son mayormente sulfatos de hierro y Fe2O3. Los procedimientos empleados y los resultados obtenidos son útiles para la toma de decisiones en mantenimiento y protección contra la corrosión de este tipo de instalaciones.The results of a detailed study of the causes of deterioration, observed in metallic ducts in a cement production plant are presented. The analysis started with a careful visual inspection, collecting samples of substrates, corrosion products and process gases. At the same time, measurements of potential, wall thickness and surface temperatures were carried out. For

General Corrosion and Localized Corrosion of Waste Package Outer Barrier

Energy Technology Data Exchange (ETDEWEB)

K.G. Mon

2004-10-01

The waste package design for the License Application is a double-wall waste package underneath a protective drip shield (BSC 2004 [DIRS 168489]; BSC 2004 [DIRS 169480]). The purpose and scope of this model report is to document models for general and localized corrosion of the waste package outer barrier (WPOB) to be used in evaluating waste package performance. The WPOB is constructed of Alloy 22 (UNS N06022), a highly corrosion-resistant nickel-based alloy. The inner vessel of the waste package is constructed of Stainless Steel Type 316 (UNS S31600). Before it fails, the Alloy 22 WPOB protects the Stainless Steel Type 316 inner vessel from exposure to the external environment and any significant degradation. The Stainless Steel Type 316 inner vessel provides structural stability to the thinner Alloy 22 WPOB. Although the waste package inner vessel would also provide some performance for waste containment and potentially decrease the rate of radionuclide transport after WPOB breach before it fails, the potential performance of the inner vessel is far less than that of the more corrosion-resistant Alloy 22 WPOB. For this reason, the corrosion performance of the waste package inner vessel is conservatively ignored in this report and the total system performance assessment for the license application (TSPA-LA). Treatment of seismic and igneous events and their consequences on waste package outer barrier performance are not specifically discussed in this report, although the general and localized corrosion models developed in this report are suitable for use in these scenarios. The localized corrosion processes considered in this report are pitting corrosion and crevice corrosion. Stress corrosion cracking is discussed in ''Stress Corrosion Cracking of the Drip Shield, the Waste Package Outer Barrier, and the Stainless Steel Structural Material'' (BSC 2004 [DIRS 169985]).

Mandibular Actinomyces osteomyelitis complicating florid cemento-osseous dysplasia: case report

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Edwards Sean P

2011-07-01

Full Text Available Abstract Background Apart from neoplastic processes, chronic disfiguring and destructive diseases of the mandible are uncommon. Case Presentation We report, perhaps for the first time, the simultaneous occurrence of two such conditions in one patient, in a case that emphasizes the importance of bone biopsy in establishing the correct diagnosis. Florid cemento-osseous dysplasia (FCOD is a chronic, disfiguring condition of the maxillofacial region. This relatively benign disease is primarily observed in middle-aged women of African ancestry. Cervicofacial actinomycosis is an uncommon and progressive infection caused by bacilli of the Actinomyces genus that typically involves intraoral soft tissues but may also involve bone. The accurate diagnosis of actinomycosis is critical for successful treatment. A diagnosis of osteomyelitis caused by Actinomyces bacteria was diagnosed by bone biopsy in a 53 year-old African-American woman with a longstanding history of FCOD after she presented with a new draining ulcer overlying the mandible. Conclusions Clinicians should be aware of the possibility of actinomycosis arising in the setting of FCOD, and the importance of bone biopsy and cultures in arriving at a definitive and timely diagnosis.

Corrosion and anticorrosion. Industrial practice

International Nuclear Information System (INIS)

Beranger, G.; Mazille, H.

2002-01-01

This book comprises 14 chapters written with the collaboration of about 50 French experts of corrosion. It is complementary to another volume entitled 'corrosion of metals and alloys' and published by the same editor. This volume comprises two parts: part 1 presents the basic notions of corrosion phenomena, the properties of surfaces, the electrochemical properties of corrosion etc.. Part 2 describes the most frequent forms of corrosion encountered in industrial environments and corresponding to specific problems of protection: marine environment, atmospheric corrosion, galvanic corrosion, tribo-corrosion, stress corrosion etc.. The first 8 chapters (part 1) treat of the corrosion problems encountered in different industries and processes: oil and gas production, chemical industry, phosphoric acid industry, PWR-type power plants, corrosion of automobile vehicles, civil engineering and buildings, corrosion of biomaterials, non-destructive testing for the monitoring of corrosion. The other chapters (part 2) deal with anticorrosion and protective coatings and means: choice of materials, coatings and surface treatments, thick organic coatings and enamels, paints, corrosion inhibitors and cathodic protection. (J.S.)

Corrosion principles and surface modification

International Nuclear Information System (INIS)

Kruger, J.

1982-01-01

This chapter examines the important strategies provided by the newer ideas of corrosion science and engineering that surface modification techniques must utilize to help prevent corrosion, especially the most damaging kind of aqueous corrosion, localized corrosion. Provides a brief introduction to the principles underlying the phenomenon of corrosion in order to use them to discuss surface modification strategies to combat corrosion. Discusses the electrochemistry of corrosion; the thermodynamics of corrosion; the kinetics of corrosion; thermodynamic strategies; and kinetic strategies (formation of more protective passive films; resistance to breakdown; ductility; repassivation)

Influencia de los componentes del concreto reforzado con fibras en sus propiedades mecánicas

OpenAIRE

González Salcedo, Luis Octavio

2013-01-01

El concreto es un material de construcción y estructural por excelencia, elaborado con cemento, agua, agregados, adiciones minerales y aditivos químicos. Sin embargo, es conocido también como un material quebradizo, característica que es contrarrestada con la incorporación de un volumen de fibra como reforzamiento de su matriz basada en cemento. La incorporación de fibra hace que se denomine como concreto reforzado con fibra, o simplemente fibrorreforzado, y se caracteriza c...

Florid cemento-osseous dysplasia: review of an uncommon fibro-osseous lesion of the jaw with important clinical implications.

Science.gov (United States)

Fenerty, Sarah; Shaw, Wei; Verma, Rahul; Syed, Ali B; Kuklani, Riya; Yang, Jie; Ali, Sayed

2017-05-01

Florid cemento-osseous dysplasia (FCOD) is a rare, benign, multifocal fibro-osseous dysplastic process affecting tooth-bearing areas of the jaw, characterized by replacement of normal trabecular bone with osseous tissue and dense acellular cementum in a fibrous stroma. It is one clinicopathologic variant in a spectrum of related non-neoplastic fibro-osseous lesions known as cemento-osseous dysplasias (CODs), thought to arise from elements of the periodontal ligament. Diagnosis primarily relies upon radiographic and clinical findings; unnecessary biopsy should be avoided, as inoculation with oral pathogens may precipitate chronic infection in these hypovascular lesions. Appropriate management of uncomplicated FCOD consists of periodic radiographic follow-up. Accordingly, it is important that both radiologists and clinicians performing endodontic interventions possess familiarity with this entity in order to prevent misdiagnosis and inappropriate intervention, which may result in a protracted clinical course. Lesions are usually asymptomatic in the absence of infection, typically discovered on routine dental radiographs or imaging performed for unrelated indications. Radiographically, the condition typically manifests as widespread non-expansile intraosseous masses of varying internal lucency and sclerosis that surround the root apices of vital teeth or edentulous areas in the posterior jaw. While all CODs share similar microscopic features, FCOD is distinguished by its multifocal distribution, involving two or more quadrants of the maxilla and mandible, often in a bilateral symmetric fashion. The vast majority of cases are sporadic, though few exhibit an autosomal dominant familial inheritance pattern. In this pictorial review, we discuss the radiologic characteristics of this entity, pertinent clinical and histologic features, differential diagnoses, and management options.

The corrosion resistance of materials used for the manufacture of ear piercing studs

Directory of Open Access Journals (Sweden)

Correa, O. V.

2003-12-01

Full Text Available Nickel containing alloys have been widely used as substrates for the manufacture of studs used for ear piercing. Unfortunately, nickel has also been related to the development of allergic contact dermatitis caused by skin sensitization due to Ni²⁺ ions. Nickel ions can be leached out into the body fluids due to corrosion reactions. Defect free coatings are very difficult to produce, and therefore nickel free materials should be used as substrates of ear piercing studs, although the commercial alloys used usually contain this element. In this study, the corrosion resistance of two kinds of commercial studs prepared with nickel containing substrates and a titanium laboratory made stud was determined in a culture medium. The corrosion resistance of the studs was investigated by means of potentiodynamic polarization tests and electrochemical impedance spectroscopy as a function of immersion time in the culture medium. The elements that leached out into the medium due to corrosion reactions were analyzed by instrumental neutron activation analysis. The surfaces of the commercial gold-coated studs were examined by scanning electron microscopy and analyzed by energy dispersive spectroscopy, both before and after exposure to the culture medium. The cytotoxicity of the tested studs was also determined in the culture medium.

Aleaciones conteniendo níquel se han utilizado como substratos para la fabricación de aretes perforantes para orejas. Desafortunadamente, el níquel ha sido relacionado con el desarrollo de una reacción alérgica conocida como dermatitis de contacto, causada por la sensibilización debido a los iones de Ni²⁺. Estos iones pueden ser liberados hacia los fluidos corporales debido a las reacciones de corrosión. Los aretes, habitualmente, se revisten con películas de oro. Sin embargo, es muy difícil hacer los revestimientos libres de defectos superficiales. Por lo tanto, materiales sin níquel deber

Development of Copper Corrosion Products and Relation between Surface Appearance and Corrosion Rate

International Nuclear Information System (INIS)

Lan, Tran Thi Ngoc; Binh, Nguyen Thi Thanh; Tru, Nguyen Nhi; Yoshino, Tsujino; Yasuki, Maeda

2008-01-01

Copper was exposed unsheltered and sheltered in four humid tropical sites, representing urban, urban-industrial, urban-marine and rural environments. The corrosion rates and the sequence of corrosion product formation are presented and discussed in relation with climatic and atmospheric pollution parameters. Chemical compositions of corrosion products were found to depend on environments and duration of exposure. In all environments, cuprite was the predominating corrosion product that formed first and continuously increased during the exposure. Among the sulphur-containing corrosion products, posnjakite and brochantite were more frequently found and the first formed earlier. Nantokite was the most common chlorine-containing products for most cases, except the high-chloride environment, where atacamite was detected instead. The corrosion rate of copper was well indicated by the colour of patina. The red-purple colour corresponded to the high corrosion rate and the greenish grey colour corresponded to the low corrosion rate. Corrosion rate of sheltered copper in urban-marine environment increased with the exposure time

Evaluation of the problematic of corrosion in bottoms of tanks of crude oil storage; Evaluacion de la problematica de corrosion en fondos de tanques de almacenamiento de petroleo crudo

Energy Technology Data Exchange (ETDEWEB)

Malo T, Jose M; Uruchurtu C, Jorge; Meza, Beatriz [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico); Lopez C, Luis F [Region Marina Suroeste, Pemex (Mexico)

2003-07-01

resultados relacionados con la agresividad corrosiva de los fluidos de agua de crudo de la Terminal Maritima de Dos Bocas (TMDB), sobre la efectividad de los metodos de control anticorrosivo y sobre medidas de control que podrian adoptarse. Asimismo, este articulo forma parte de un trabajo realizado por personal del Instituto de Investigaciones Electricas (IIE) durante el ano 2002. La corrosion en tanques es de naturaleza electroquimica y tiene su origen en la fase acuosa que acompana al crudo al ser extraido del subsuelo. En el caso de los tanques de almacenamiento, la fase acuosa se separa en el fondo, ocasionado el mojado de las placas de acero del fondo y su degradacion. Debido al limitado acceso al interior del tanque durante su operacion, se diseno un dispositivo de pruebas que fue conectado a una valvula de drenado de un tanque de la terminal. El trabajo experimental busco evaluar la agresividad de los fluidos, el tipo de productos de corrosion formados y la eficacia de la proteccion catodica y de los recubrimientos. Adicionalmente, se recolectaron muestras de fluidos para analizar el nivel de agresividad natural que presenta el agua de los tres tipos de crudos: Maya, Olmeca e Istmo, manejados en la terminal, estudiando muestras de acero y de fluidos de planta bajo condiciones controladas de laboratorio. La agresividad se obtuvo de mediciones de velocidades de reaccion de corrosion y de analisis de actividad microbiana. Se analizo la factibilidad de aplicar el metodo de proteccion catodica, observando su efectividad, asi como formas particulares de corrosion como la que ocurre en los pontones. Los resultados del estudio conducen a proponer un esquema de monitoreo para el seguimiento de la integridad de los recubrimientos, la operacion de la proteccion catodica y la corrosion en tanques, con el que se podria tener un mejor control de la operacion de los metodos anticorrosivos y de la degradacion que ocurre por corrosion.

Behaviour of corroded steel in a Ca(OH2-saturated solution and in cement mortar. Possibility of rehabilitation

Directory of Open Access Journals (Sweden)

Hernández, L. S.

2007-03-01

Full Text Available The present study compared the response of rust-free and corroded steel electrodes in Ca(OH2-saturated solutions and in cement mortar, essentially defined in terms of polarization resistance as measured with gravimetric, metallographic and electrochemical methods. Answers were sought for the following questions, which persist despite the use of reinforced concrete (RC in building for over a century: At what corrosion rate is RC durability seriously compromised? Does restoration of the initial conditions in properly manufactured concrete guarantee repassivation of corroded steel? Does the use of inhibitors enhance repassivation? Does the nature of the corrosion products have any significant effect on the response of corroded steel reinforcement? The results obtained in indicated that the effectiveness of preventive methods is much more closely related to the degree of existing corrosion than to the nature of the corrosion products.En el presente trabajo se analizan las respuestas de electrodos de acero, limpios y precorroídos, en soluciones saturadas de Ca(OH2 y en mortero de cemento, recurriendo para ello a técnicas gravimétricas, metalográficas y electroquímicas, esencialmente a medidas de resistencia de polarización. Se intenta encontrar respuesta a las siguientes dudas persistentes después de más de un siglo de utilización de las estructuras de hormigón armado (EHA: ¿qué velocidades de corrosión comprometen seriamente la durabilidad de las EHA? ¿La restauración de las condiciones iniciales de un hormigón correctamente fabricado garantiza la recuperación del estado pasivo en los refuerzos ya corroídos? ¿La utilización de inhibidores facilita la repasivación de los refuerzos? ¿Cambia la naturaleza de los productos de corrosión sustancialmente la respuesta de las armaduras ya corroídas? Los resultados obtenidos indican que la eficacia de las medidas preventivas resulta mucho más condicionada por el grado de

Effect of Flow Velocity on Corrosion Rate and Corrosion Protection Current of Marine Material

Energy Technology Data Exchange (ETDEWEB)

Lee, Seong Jong [Kunsan National University, Kunsan (Korea, Republic of); Han, Min Su; Jang, Seok Ki; Kim, Seong Jong [Mokpo National Maritime University, Mokpo (Korea, Republic of)

2015-10-15

In spite of highly advanced paint coating techniques, corrosion damage of marine metal and alloys increase more and more due to inherent micro-cracks and porosities in coatings formed during the coating process. Furthermore, flowing seawater conditions promote the breakdown of the protective oxide of the materials introducing more oxygen into marine environments, leading to the acceleration of corrosion. Various corrosion protection methods are available to prevent steel from marine corrosion. Cathodic protection is one of the useful corrosion protection methods by which the potential of the corroded metal is intentionally lowered to an immune state having the advantage of providing additional protection barriers to steel exposed to aqueous corrosion or soil corrosion, in addition to the coating. In the present investigation, the effect of flow velocity was examined for the determination of the optimum corrosion protection current density in cathodic protection as well as the corrosion rate of the steel. It is demonstrated from the result that the material corrosion under dynamic flowing conditions seems more prone to corrosion than under static conditions.

NASA's Beachside Corrosion Test Site and Current Environmentally Friendly Corrosion Control Initiatives

Science.gov (United States)

Russell, Richard W.; Calle, Luz Marina; Johnston, Frederick; Montgomery, Eliza L.; Curran, Jerome P.; Kolody, Mark R.

2013-01-01

NASA began corrosion studies at the Kennedy Space Center (KSC) in 1966 during the Gemini/Apollo Programs with the evaluation of long-term corrosion protective coatings for carbon steel. KSC's Beachside Corrosion Test Site (BCTS), which has been documented by the American Society of Materials (ASM) as one of the most corrosive, naturally occurring, environments in the world, was established at that time. With the introduction of the Space Shuttle in 1981, the already highly corrosive conditions at the launch pad were rendered even more severe by the acid ic exhaust from the solid rocket boosters. In the years that followed, numerous studies have identified materials, coatings, and maintenance procedures for launch hardware and equipment exposed to the highly corrosive environment at the launch pad. This paper presents a historical overview of over 45 years of corrosion and coating evaluation studies and a description of the BCTS's current capabilities. Additionally, current research and testing programs involving chromium free coatings, environmentally friendly corrosion preventative compounds, and alternates to nitric acid passivation will be discussed.

NASA's Corrosion Technology Laboratory at the Kennedy Space Center: Anticipating, Managing, and Preventing Corrosion

Science.gov (United States)

Calle, Luz Marina

2015-01-01

The marine environment at NASAs Kennedy Space Center (KSC) has been documented by ASM International (formerly American Society for Metals) as the most corrosive in North America. With the introduction of the Space Shuttle in 1981, the already highly corrosive conditions at the launch pads were rendered even more severe by the highly corrosive hydrochloric acid (HCl) generated by the solid rocket boosters (SRBs). Numerous failures at the launch pads are caused by corrosion. The structural integrity of ground infrastructure and flight hardware is critical to the success, safety, cost, and sustainability of space missions. NASA has over fifty years of experience dealing with unexpected failures caused by corrosion and has developed expertise in corrosion control in the launch and other environments. The Corrosion Technology Laboratory at KSC evolved, from what started as an atmospheric exposure test site near NASAs launch pads, into a capability that provides technical innovations and engineering services in all areas of corrosion for NASA, external partners, and customers.This paper provides a chronological overview of NASAs role in anticipating, managing, and preventing corrosion in highly corrosive environments. One important challenge in managing and preventing corrosion involves the detrimental impact on humans and the environment of what have been very effective corrosion control strategies. This challenge has motivated the development of new corrosion control technologies that are more effective and environmentally friendly. Strategies for improved corrosion protection and durability can have a huge impact on the economic sustainability of human spaceflight operations.

Fighting corrosion in India

Energy Technology Data Exchange (ETDEWEB)

Rajagopalan, K S; Rangaswamy, N S

1979-03-01

A survey covers the cost of corrosion in India; methods of preventing corrosion in industrial plants; some case histories, including the prevention of corrosion in pipes through which fuels are pumped to storage and the stress-corrosion cracking of evaporators in fertilizer plants; estimates of the increase in demand in 1979-89 for anticorrosion products and processes developed by the Central Electrochemical Research Institute (CECRI) at Karaikudi, India; industries that may face corrosion problems requiring assistance from CECRI, including the light and heavy engineering structural, and transport industries and the chemical industry; and some areas identified for major efforts, including the establishment of a Corrosion Advisory Board with regional centers and the expansion of the Tropical Corrosion Testing Station at Mandapam Camp, Tamil Nadu.

Corrosion evaluation technology

International Nuclear Information System (INIS)

Kim, Uh Chul; Han, Jeong Ho; Nho, Kye Ho; Lee, Eun Hee; Kim, Hong Pyo; Hwang, Seong Sik; Lee, Deok Hyun; Hur, Do Haeng; Kim, Kyung Mo.

1997-09-01

A multifrequency ACPD system was assembled which can measure very small crack. Stress corrosion cracking test system with SSRT operating high temperature was installed. Stress corrosion cracking test of newly developed alloy 600 and existing alloy 600 was carried out in steam atmosphere of 400 deg C. No crack was observed in both materials within a test period of 2,000 hrs. Corrosion fatigue test system operating at high temperature was installed in which fatigue crack was measured by CDPD. Lead enhanced the SCC of the Alloy 600 in high temperature water, had a tendency to modify a cracking morphology from intergranular to transgranular. Pit initiation preferentially occurred at Ti-rich carbide. Resistance to pit initiation decreased with increasing temperature up to 300 deg C. Test loop for erosion corrosion was designed and fabricated. Thin layer activation technique was very effective in measuring erosion corrosion. Erosion corrosion of a part of secondary side pipe was evaluated by the Check Family Codes of EPRI. Calculated values of pipe thickness by Check Family Codes coincided with the pipe thickness measured by UT with an error of ± 20%. Literature review on turbine failure showed that failure usually occurred in low pressure turbine rotor disc and causes of failure are stress corrosion cracking and corrosion fatigue. (author). 12 refs., 20 tabs., 77 figs

Corrosion Cost and Corrosion Map of Korea - Based on the Data from 2005 to 2010

International Nuclear Information System (INIS)

Kim, Y. S.; Lim, H. K.; Kim, J. J.; Hwang, W. S.; Park, Y. S.

2011-01-01

Corrosion of metallic materials occurs by the reaction with corrosive environment such as atmosphere, marine, soil, urban, high temperature etc. In general, reduction of thickness and cracking and degradation are resulted from corrosion. Corrosion in all industrial facilities and infrastructure causes large economic losses as well as a large number of accidents. Economic loss by corrosion has been reported to be nearly 1-6% of GNP or GDP. In order to reduce corrosion damage of industrial facilities, corrosion map as well as a systematic investigation of the loss of corrosion in each industrial sector is needed. The Corrosion Science Society of Korea in collaboration with 15 universities and institutes has started to survey on the cost of corrosion and corrosion map of Korea since 2005. This work presents the results of the survey on cost of corrosion by Uhlig, Hoar, and input-output methods, and the evaluation of atmospheric corrosion rate of carbon steel, weathering steel, galvanized steel, copper, and aluminum in Korea. The total corrosion cost was estimated in terms of the percentage of the GDP of industry sectors and the total GDP of Korea. According to the result of Input/output method, corrosion cost of Korea was calculated as 2.9% to GDP (2005). Time of wetness was shown to be categories 3 to 4 in all exposure areas. A definite seasonal difference was observed in Korea. In summer and fall, time of wetness was higher than in other seasons. Because of short exposure period (12 months), significant corrosion trends depending upon materials and exposure corrosion environments were not revealed even though increased mass loss and decreased corrosion rate by exposure time

PENETRACIÓN Y DISOLUCIÓN DEL REFRACTARIO DE CROMO-MAGNESIO POR ESCORIAS FAYALÍTCAS

Directory of Open Access Journals (Sweden)

VANESA BAZÁN

2012-01-01

Full Text Available Los refractarios magnesia-cromo se han utilizado con éxito en diferentes procesos metalúrgicos a altas temperaturas, tales como hierro y acero, la industria del cemento y procesos pirometalúrgicos no ferrosos. En particular en la fundición, en los procesos de conversión de refino de cobre. Esos materiales tienen buenas características en relación con el uso y los requisitos de resistencia al choque térmico. Sin embargo, representan un problema importante en la contaminación del medio ambiente. El objetivo de este estudio fue investigar las interacciones entre la escoria generada en el convertidor Peirce-Smith e cobre y los ladrillos refractarios de magnesia-cromo ladrillos. Los fenómenos de infiltración y ataques químicos en el material refractario causado por la escoria formada durante el proceso de conversión de cobre se han estudiado mediante el desarrollo de las diferentes pruebas de laboratorio a temperaturas de hasta 1300 ° C.

Portland blended cements: demolition ceramic waste management; Cementos Portland con adiciones: manejo de residuos cerámicos de demolición.

Energy Technology Data Exchange (ETDEWEB)

Trezza, M.A.; Zito, S.; Tironi, A.; Irassar, E.F.; Rahhal, V.F.

2017-07-01

Demolition ceramic wastes (DCWs) were investigated in order to determine their potential use as supplementary cementitious materials in Portland Blended Cements (PBCs). For this purpose, three ceramic wastes were investigated. After characterization of the materials used, the effect of ceramic waste replacement (8, 24 and 40% by mass) was analyzed. Pozzolanic activity, hydration progress, workability and compressive strength were determined at 2, 7 and 28 days. The results showed that the ground wastes behave as filler at an early age, but as hydration progresses, the pozzolanic activity of ceramic waste contributes to the strength requirement. [Spanish] Se estudiaron residuos cerámicos de demolición (DCWs) a fin de determinar su potencial uso como materiales cementicios suplementarios en cementos mezcla (PBC). Para este propósito, se investigaron tres residuos cerámicos. Luego de la caracterización de los materiales a utilizar, se analizó el efecto del reemplazo por residuos cerámico (8, 24 y 40% en peso). Se estudió la actividad puzolánica, el progreso de la hidratación, la trabajabilidad y la resistencia a compresión a 2, 7 y 28 días. Los resultados mostraron que los residuos molidos se comportaron como fillers a edades tempranas, pero con el progreso de la hidratación, la actividad puzolánica de los residuos cerámicos contribuye a los requerimientos de resistencia.

Exploratory shaft liner corrosion estimate

International Nuclear Information System (INIS)

Duncan, D.R.

1985-10-01

An estimate of expected corrosion degradation during the 100-year design life of the Exploratory Shaft (ES) is presented. The basis for the estimate is a brief literature survey of corrosion data, in addition to data taken by the Basalt Waste Isolation Project. The scope of the study is expected corrosion environment of the ES, the corrosion modes of general corrosion, pitting and crevice corrosion, dissimilar metal corrosion, and environmentally assisted cracking. The expected internal and external environment of the shaft liner is described in detail and estimated effects of each corrosion mode are given. The maximum amount of general corrosion degradation was estimated to be 70 mils at the exterior and 48 mils at the interior, at the shaft bottom. Corrosion at welds or mechanical joints could be significant, dependent on design. After a final determination of corrosion allowance has been established by the project it will be added to the design criteria. 10 refs., 6 figs., 5 tabs

Precisiones sobre la corrosión del acero en contacto con hormigón

Directory of Open Access Journals (Sweden)

Andrade, C.

1982-09-01

Full Text Available In this paper, we emphasize that now it is possible to use some electrochemical non-destructive techniques for measuring the corrosion rate of the metals. Also, it is possible to use the gravimetric determinations if the appropriate instrumentation is not available. The simple visual observation is a good complementary technique but it must not be used alone because of its subjectivity. Also, we stress some aspects, such as the influence of the alkalinity and the humidity, about the corrosion, that the bare and galvanized steel, can suffer in contact with construction materials. We analyze mainly, the influence of the type of cement on the risk of corrosion of both kinds of metals.

En los presentes comentarios se insiste en que, para evaluar la velocidad de corrosión de los metales, en la actualidad se pueden utilizar técnicas electroquímicas no destructivas que permiten seguir la evolución del proceso diariamente, o bien, en el caso de no contar con los aparatos apropiados, se puede acudir a una determinación gravimétrica de la pérdida de metal. La simple observación visual es una valiosa indicación complementaria de las técnicas antes mencionadas, pero no debe utilizarse como técnica de medida única por la subjetividad que conlleva. También se precisan algunos aspectos sobre la corrosión que el acero desnudo y el galvanizado pueden sufrir por estar en contacto con materiales de construcción, como son la influencia de la alcalinidad y de la humedad del medio y, fundamentalmente, se analiza la influencia que puede ejercer el tipo de cemento en el riesgo de corrosión de ambas clases de metales.

Dictionary corrosion and corrosion control. English-German/German-English. Fachwoerterbuch Korrosion und Korrosionsschutz. Englisch-Deutsch/Deutsch-Englisch

Energy Technology Data Exchange (ETDEWEB)

1985-01-01

This dictionary has 13000 entries in both languages. Keywords and extensive accompanying information simplify the choice of word for the user. The following topics are covered: Theoretical principles of corrosion; Corrosion of the metals and alloys most frequently used in engineering. Types of corrosion - (chemical-, electro-chemical, biological corrosion); forms of corrosion (superficial, pitting, selective, intercrystalline and stress corrosion; vibrational corrosion cracking); erosion and cavitation. Methods of corrosion control (material selection, temporary corrosion protection media, paint and plastics coatings, electro-chemical coatings, corrosion prevention by treatment of the corrosive media); Corrosion testing methods.

Concrete Durability Properties and Microstructural Analysis of Cement Pastes with Nopal Cactus Mucilage as a Natural Additive

Directory of Open Access Journals (Sweden)

Ramírez-Arellanes, S.

2012-09-01

Full Text Available The present study evaluated the addition of a 3% nopal cactus mucilage solution to cement pastes, in its effects on setting times, flow, hydration, and microstructure, as well as on capillary water absorption and chloride diffusion in concrete. Hydration was characterized through XRD and microstructure was characterized with SEM. The mucilage solution/cement and water/cement ratios tested were 0.30, 0.45, and 0.60. The results in cement pastes indicate that the addition of mucilage increases setting times, reduces flow, slows cement hydration, and inhibits the formation of calcium hydroxide crystals in comparison with the control. Capillary absorption was significantly reduced in concrete containing mucilage, and chloride diffusion coefficients dropped up to 20% in the mixture with a mucilage/cement ratio = 0.30. The mixture with a mucilage/cement ratio = 0.45 displayed marginal reduction, and the mixture with mucilage/cement ratio = 0.60 exhibited a diffusion coefficient that was greater than the control for the specimens without moist curing.En esta investigación se evaluó el efecto de una solución de mucílago de nopal al 3% en los tiempos de fraguado, fluidez, hidratación y microestructura de pastas de cemento, y absorción capilar de agua y difusión de cloruros en concreto. La hidratación fue caracterizada por XRD y la microestructura por medio de SEM. Las relaciones solución de mucílago/cemento y agua/cemento fueron 0,30; 0,45 y 0,60. Los resultados en las pastas de cemento indican que el mucílago retarda los tiempos de fraguado, reduce la fluidez, retarda la hidratación del cemento, e inhibe la formación de cristales de hidróxido de calcio, comparados con los controles. La absorción capilar en concreto conteniendo mucílago se redujo significativamente y los coeficientes de difusión de cloruros disminuyeron hasta 20% en la mezcla mucílago/cemento = 0.30. En la relación mucílago/cemento = 0.45 la reducción fue marginal y

Determination of calcium in cements, by atomic absorption

Directory of Open Access Journals (Sweden)

Triviño, Fernando

1975-03-01

Full Text Available Not availableEl elemento más difícil de analizar por absorción atómica en el cemento portland es el calcio. Los resultados se obtienen por repetición de un gran número de análisis de la misma muestra y suelen diferir entre ellos. La repetición necesaria para obtener una seguridad estadística exige un aumento en el tiempo del análisis. Sin embargo el análisis del calcio, exacto, preciso y rápido, es una necesidad en la industria del cemento. El análisis del calcio exige una gran dilución del problema con el fin de que los resultados cumplan la ley de Beer y eliminar las interferencias ocasionadas por el silicio y el aluminio, para lo cual se añade lantano a la disolución problema.

Penetration of corrosion products and corrosion-induced cracking in reinforced cementitious materials

DEFF Research Database (Denmark)

Michel, Alexander; Pease, Brad J.; Peterova, Adela

2014-01-01

This paper describes experimental investigations on corrosion-induced deterioration in reinforced cementitious materials and the subsequent development and implementation of a novel conceptual model. Rejnforced mortar specimens of varying water-to-cement ratios were subjected to current-induced c......This paper describes experimental investigations on corrosion-induced deterioration in reinforced cementitious materials and the subsequent development and implementation of a novel conceptual model. Rejnforced mortar specimens of varying water-to-cement ratios were subjected to current......-dependent concentrations of corrosion products averaged through the specimen thickness. Digital image correlation (DIC) was used to measure corrosion-induced deformations including deformations between steel and cementitious matrix as well as formation and propagation of corrosion-induced cracks. Based on experimental...... observations, a conceptual model was developed to describe the penetration of solid corrosion products into capillary pores of the cementitious matrix. Only capillary pores within a corrosion accommodating region (CAR), i.e. in close proximity of the steel reinforcement, were considered accessible...

NASA's Corrosion Technology Laboratory at the Kennedy Space Center: Anticipating, Managing, and Preventing Corrosion

Science.gov (United States)

Calle, Luz Marina

2014-01-01

Corrosion is the degradation of a material that results from its interaction with the environment. The marine environment at NASAs Kennedy Space Center (KSC) has been documented by ASM International (formerly American Society for Metals) as the most corrosive in the United States. With the introduction of the Space Shuttle in 1981, the already highly corrosive conditions at the launch pads were rendered even more severe by the 70 tons of highly corrosive hydrochloric acid that were generated by the solid rocket boosters. Numerous failures at the launch pads are caused by corrosion.The structural integrity of ground infrastructure and flight hardware is critical to the success, safety, cost, and sustainability of space missions. As a result of fifty years of experience with launch and ground operations in a natural marine environment that is highly corrosive, NASAs Corrosion Technology Laboratory at KSC is a major source of corrosion control expertise in the launch and other environments. Throughout its history, the Laboratory has evolved from what started as an atmospheric exposure facility near NASAs launch pads into a world-wide recognized capability that provides technical innovations and engineering services in all areas of corrosion for NASA and external customers.This presentation will provide a historical overview of the role of NASAs Corrosion Technology in anticipating, managing, and preventing corrosion. One important challenge in managing and preventing corrosion involves the detrimental impact on humans and the environment of what have been very effective corrosion control strategies. This challenge has motivated the development of new corrosion control technologies that are more effective and environmentally friendly. Strategies for improved corrosion protection and durability can have a huge impact on the economic sustainability of human spaceflight operations.

Corrosion behavior of corrosion resistant alloys in stimulation acids

Energy Technology Data Exchange (ETDEWEB)

Cheldi, Tiziana [ENI E and P Division, 20097 San Donato Milanese Milano (Italy); Piccolo, Eugenio Lo; Scoppio, Lucrezia [Centro Sviluppo Materiali, via Castel Romano 100, 00128 Rome (Italy)

2004-07-01

In the oil and gas industry, selection of CRAs for downhole tubulars is generally based on resistance to corrosive species in the production environment containing CO{sub 2}, H{sub 2}S, chloride and in some case elemental sulphur. However, there are non-production environments to which these materials must also be resistant for either short term or prolonged duration; these environments include stimulation acids, brine and completion fluids. This paper reports the main results of a laboratory study performed to evaluate the corrosion and stress corrosion behaviour to the acidizing treatments of the most used CRAs for production tubing and casing. Laboratory tests were performed to simulate both 'active' and 'spent' acids operative phases, selecting various environmental conditions. The selected steel pipes were a low alloyed steel, martensitic, super-martensitic, duplex 22 Cr, superduplex 25 Cr and super-austenitic stainless steels (25 Cr 35 Ni). Results obtained in the 'active' acid environments over the temperature range of 100-140 deg. C, showed that the blend acids with HCl at high concentration and HCl + HF represented too much severe conditions, where preventing high general corrosion and heavy localised corrosion by inhibition package becomes very difficult, especially for duplex steel pipe, where, in some case, the specimens were completely dissolved into the solution. On the contrary, all steels pipes were successfully protected by inhibitor when organic acid solution (HCOOH + CH{sub 3}COOH) were used. Furthermore, different effectiveness on corrosion protection was showed by the tested inhibitors packages: e.g. in the 90% HCl at 12% + 10 CH{sub 3}COOH acid blend. In 'spent' acid environments, all steel pipes showed to be less susceptible to the localised and general corrosion attack. Moreover, no Sulphide Stress Corrosion Cracking (SSC) was observed. Only one super-austenitic stainless steel U-bend specimen showed

Corrosion failure analysis as related to prevention of corrosion failures

International Nuclear Information System (INIS)

Suss, H.

1977-10-01

The factors and conditions which have contributed to many of the corrosion related service failures are discussed based on a review of actual case histories. The anti-corrosion devices which developed as a result of these failure analyses are reviewed, and the method which must be adopted and used to take advantage of the available corrosion prevention techniques is discussed

Corrosion and corrosion fatigue of airframe aluminum alloys

Science.gov (United States)

Chen, G. S.; Gao, M.; Harlow, D. G.; Wei, R. P.

1994-01-01

Localized corrosion and corrosion fatigue crack nucleation and growth are recognized as degradation mechanisms that effect the durability and integrity of commercial transport aircraft. Mechanically based understanding is needed to aid the development of effective methodologies for assessing durability and integrity of airframe components. As a part of the methodology development, experiments on pitting corrosion, and on corrosion fatigue crack nucleation and early growth from these pits were conducted. Pitting was found to be associated with constituent particles in the alloys and pit growth often involved coalescence of individual particle-nucleated pits, both laterally and in depth. Fatigue cracks typically nucleated from one of the larger pits that formed by a cluster of particles. The size of pit at which fatigue crack nucleates is a function of stress level and fatigue loading frequency. The experimental results are summarized, and their implications on service performance and life prediction are discussed.

Atmospheric corrosion of uranium-carbon alloys; Corrosion atmospherique des alliages uranium-carbone

Energy Technology Data Exchange (ETDEWEB)

Rousset, P; Accary, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1965-07-01

The authors study the corrosion of uranium-carbon alloys having compositions close to that of the mono-carbide; they show that the extent of the observed corrosion effects increases with the water vapour content of the surrounding gas and they conclude that the atmospheric corrosion of these alloys is due essentially to the humidity of the air, the effect of the oxygen being very slight at room temperature. They show that the optimum conditions for preserving U-C alloys are either a vacuum or a perfectly dry argon atmosphere. The authors have also established that the type of corrosion involved is a corrosion which 'cracks under stress' and is transgranular (it can also be intergranular in the case of sub-stoichiometric alloys). They propose, finally, two hypotheses for explaining this mechanism, one of which is illustrated by the existence, at the fissure interface, of corrosion products which can play the role of 'corners' in the mono-carbide grains. (authors) [French] Les auteurs etudient la corrosion des alliages uranium-carbone de composition voisine du monocarbure; ils montrent que l'importance des effets de la corrosion observee augmente avec la teneur en vapeur d'eau du milieu gazeux ambiant et concluent que la corrosion atmospherique de ces alliages est due essentiellement a l'humidite de l'air, l'action de l'oxygene de l'air etant tres faible a la temperature ambiante. Ils indiquent que les conditions optimales de conservation des alliages U-C sont le vide ou une atmosphere d'argon parfaitement desseches. D'autre part, les auteurs etablissent que le type de corrosion mis en jeu est une corrosion 'fissurante sous contrainte', transgranulaire (pouvant egalement etre intergranulaire dans le cas d'alliages sous-stoechiometriques). Ils proposent enfin deux hypotheses pour rendre compte de ce mecanisme, dont l'une est illustree par la mise en evidence, a l'interface des fissures, de produits de corrosion pouvant jouer le role de 'coins' dans les grains de

Corrosion and corrosion protection of support structures for offshore wind energy devices (OWEA)

Energy Technology Data Exchange (ETDEWEB)

Momber, A. [Muehlhan AG, Schlinckstrasse 3, D-21107 Hamburg (Germany)

2011-05-15

The paper provides a review about the corrosion and corrosion protection of offshore wind energy devices (OWEA). Firstly, special features resulting from location and operation of OWEA are being discussed. Secondly, types of corrosion and corrosion phenomena are summarized in a systematic way. Finally, practical solutions to the corrosion protection of OWEA, including steel allowances, cathodic protection and coatings and linings, are discussed. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Corrosion behaviors and effects of corrosion products of plasma electrolytic oxidation coated AZ31 magnesium alloy under the salt spray corrosion test

Science.gov (United States)

Wang, Yan; Huang, Zhiquan; Yan, Qin; Liu, Chen; Liu, Peng; Zhang, Yi; Guo, Changhong; Jiang, Guirong; Shen, Dejiu

2016-08-01

The effects of corrosion products on corrosion behaviors of AZ31 magnesium alloy with a plasma electrolytic oxidation (PEO) coating were investigated under the salt spray corrosion test (SSCT). The surface morphology, cross-sectional microstructure, chemical and phase compositions of the PEO coating were determined using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction analysis (XRD), respectively. Further, the corrosion process of the samples under the SSCT was examined in a non-aqueous electrolyte (methanol) using electrochemical impedance spectroscopy (EIS) coupled with equivalent circuit. The results show that the inner layer of the coating was destroyed firstly and the corrosion products have significant effects on the corrosion behaviors of the coating. The results above are discussed and an electrochemical corrosion model is proposed in the paper.

Long-term corrosion studies

International Nuclear Information System (INIS)

Gdowski, G.

1998-01-01

The scope of this activity is to assess the long-term corrosion properties of metallic materials under consideration for fabricating waste package containers. Three classes of metals are to be assessed: corrosion resistant, intermediate corrosion resistant, and corrosion allowance. Corrosion properties to be evaluated are general, pitting and crevice corrosion, stress-corrosion cracking, and galvanic corrosion. The performance of these materials will be investigated under conditions that are considered relevant to the potential emplacement site. Testing in four aqueous solutions, and vapor phases above them, and at two temperatures are planned for this activity. (The environmental conditions, test metals, and matrix are described in detail in Section 3.0.) The purpose and objective of this activity is to obtain the kinetic and mechanistic information on degradation of metallic alloys currently being considered for waste package containers. This information will be used to provide assistance to (1) waste package design (metal barrier selection) (E-20-90 to E-20-92), (2) waste package performance assessment activities (SIP-PA-2), (3) model development (E-20-75 to E-20-89). and (4) repository license application

Corrosion of beryllium

International Nuclear Information System (INIS)

Mueller, J.J.; Adolphson, D.R.

1987-01-01

The corrosion behavior of beryllium in aqueous and elevated-temperature oxidizing environments has been extensively studied for early-intended use of beryllium in nuclear reactors and in jet and rocket propulsion systems. Since that time, beryllium has been used as a structural material in les corrosive environments. Its primary applications include gyro systems, mirror and reentry vehicle structures, and aircraft brakes. Only a small amount of information has been published that is directly related to the evaluation of beryllium for service in the less severe or normal atmospheric environments associated with these applications. Despite the lack of published data on the corrosion of beryllium in atmospheric environments, much can be deduced about its corrosion behavior from studies of aqueous corrosion and the experiences of fabricators and users in applying, handling, processing, storing, and shipping beryllium components. The methods of corrosion protection implemented to resist water and high-temperature gaseous environments provide useful information on methods that can be applied to protect beryllium for service in future long-term structural applications

Initiation and inhibition of pitting corrosion on reinforcing steel under natural corrosion conditions

Energy Technology Data Exchange (ETDEWEB)

Abd El Wanees, S., E-mail: s_wanees@yahoo.com [Chemistry Department, Faculty of Science, University of Tabuk, Tabuk (Saudi Arabia); Chemistry Department, Faculty of Science, Zagazig University, Zagazig 44519 (Egypt); Bahgat Radwan, A. [Center for Advanced Materials, Qatar University, Doha 2713 (Qatar); Alsharif, M.A. [Chemistry Department, Faculty of Science, University of Tabuk, Tabuk (Saudi Arabia); Abd El Haleem, S.M. [Chemistry Department, Faculty of Science, Zagazig University, Zagazig 44519 (Egypt)

2017-04-01

Initiation and inhibition of pitting corrosion on reinforcing steel in saturated, naturally aerated Ca(OH){sub 2} solutions, under natural corrosion conditions, are followed through measurements of corrosion current, electrochemical impedance spectroscopy and SEM investigation. Induction period for pit initiation and limiting corrosion current for pit propagation are found to depend on aggressive salt anion and cation-types, as well as, concentration. Ammonium chlorides and sulfates are more corrosive than the corresponding sodium salts. Benzotriazole and two of its derivatives are found to be good inhibitors for pitting corrosion of reinforcing steel. Adsorption of these compounds follows a Langmuir adsorption isotherm. The thermodynamic functions ΔE{sup ∗}, ΔH{sup ∗} and ΔS{sup ∗} for pitting corrosion processes in the absence and presence of inhibitor are calculated and discussed. - Highlights: • Cl{sup −} and SO{sub 4} {sup 2-} induce pitting corrosion on passive reinforcing steel. • Initiation and propagation of pitting depend on cation and anion types. • Inhibition is based on adsorption according to Langmuir isotherm.

Real time corrosion monitoring in atmosphere using automated battery driven corrosion loggers

DEFF Research Database (Denmark)

Prosek, T.; Kouril, M.; Hilbert, Lisbeth Rischel

2008-01-01

diminishes due to corrosion. Zinc, iron, copper and nickel sensors at several thicknesses are available. Sensitivity of the corrosion measurement varies from 1 to 10 nm depending on the type and thickness of the sensor. Changes in the air corrosivity can be thus detected within hours or even tens of minutes......A logger enabling continuous measurement of corrosion rate of selected metals in indoor and outdoor atmospheres has been developed. Principle of the measurement method is based on the increasing electrical resistance of a measuring element made of the material concerned as its cross-sectional area....... The logger lifetime in medium corrosive environments is designed to be 2 years with full autonomy. Data on the sensor corrosion rate are available any time through GPRS connection or by a non-contact inductive reading without the need of retracting the logger from the exposure site....

The corrosion behaviour of nanograined metals and alloys

Directory of Open Access Journals (Sweden)

Herrasti, P.

2012-10-01

Full Text Available There has been considerable interest in the properties of nanocrystalline materials over the last decade. Such materials include metals and alloys with a crystal size within the order of 1 to 100 nm. The interest arises due to the substantial differences in electrical, optical and magnetic properties and also due to their high adsorption capability and chemical reactivity compared to their larger grained counterparts. In this paper, the corrosion of nanocrystalline metals and alloys is investigated and compared to the corrosion of microcrystalline materials having a similar composition. The focus is on the corrosion of nickel, copper, cobalt and iron alloys. Key aspects of different corrosion behaviour such grain boundaries and size are identified.

En la última década ha habido un gran interes en las propiedades de materiales nanocristalinos. Estos materiales incluyen metales y aleaciones con un tamaño de cristal del orden de 1 a 100 nm. El interes por estos materiales es debido a las grandes diferencias en cuanto a sus propiedades electricas, opticas y magneticas, asi como a su alta capacidad de adsorción y reactividad química en relación a los mismos materiales con tamaños de grano mayores. En este trabajo se ha investigado y comparado la corrosión de materiales nano y microcristalinos de similar composición química. Principalmente se ha centrado en la corrosión de metales tales como niquel, cobre, cobalto y aleaciones de hierro. Se ha comprobado que los diferentes comportamientos frente al proceso de corrosión están intimamente ligados con los bordes de grano y el tamaño de dichos granos.

Severe florid cemento-osseous dysplasia: a case report treated conservatively and literature review.

Science.gov (United States)

Sarmento, Dmitry José de Santana; Monteiro, Bárbara Vanessa de Brito; de Medeiros, Ana Miryam Costa; da Silveira, Ericka Janine Dantas

2013-03-01

Florid cemento-osseous dysplasia (FCOD) has been described as a condition that characteristically affects the jaws of middle-aged black women. Radiographically, FCOD appears as dense, lobulated masses, often symmetrically located in various regions of the jaws. FCOD is usually asymptomatic. In severe cases, focal expansion may occur due to infection. Management of the symptomatic patient is more difficult due to the avascular nature of the lesion which contributes to susceptibility severe infection, bone sequestration, and osteomyelitis when surgery is performed. This paper presents a rare case of severe FCOD; the black woman patient was diagnosed based on clinical and radiographic findings and treated conservatively. The examination of panoramic radiographs revealed a multiple sclerotic masses with radiolucent borders, found in the mandible and maxilla which were symmetrical at presentation. The patient continuous with the follow-up. This report confirms that a diagnosis can be made with accurate clinical and radiographic assessment. The correct selection of treatment for FCOD depends on this information.

Corrosion-resistant metal surfaces

Science.gov (United States)

Sugama, Toshifumi [Wading River, NY

2009-03-24

The present invention relates to metal surfaces having thereon an ultrathin (e.g., less than ten nanometer thickness) corrosion-resistant film, thereby rendering the metal surfaces corrosion-resistant. The corrosion-resistant film includes an at least partially crosslinked amido-functionalized silanol component in combination with rare-earth metal oxide nanoparticles. The invention also relates to methods for producing such corrosion-resistant films.

Corrosion testing facilities in India

International Nuclear Information System (INIS)

Viswanathan, R.; Subramanian, Venu

1981-01-01

Major types of corrosion tests, establishment of specifications on corrosion testing and scope of their application in practice are briefly described. Important organizations in the world which publish specifications/standards are listed. Indian organizations which undertake corrosion testing and test facilities available at them are also listed. Finally in an appendix, a comprehensive list of specifications relevant to corrosion testing is given. It is arranged under the headings: environmental testing, humidity tests, salt spray/fog tests, immersion tests, specification corrosion phenomena, (tests) with respect to special corrosion media, (tests) with respect to specific corrosion prevention methods, and specific corrosion tests using electrical and electrochemical methods (principles). Each entry in the list furnishes information about: nature of the test, standard number, and its specific application. (M.G.B.)

Corrosion characteristics of K-claddings

International Nuclear Information System (INIS)

Park, J. Y.; Choi, B. K.; Jung, Y. H.; Jung, Y. H.

2004-01-01

The Improvement of the corrosion resistance of nuclear fuel claddings is the critical issue for the successful development of the high burn-up fuel. KAERI have developed the K-claddings having a superior corrosion resistance by controlling the alloying element addition and optimizing the manufacturing process. The comparative evaluation of the corrosion resistance for K-claddings and the foreign claddings was performed and the effect of the heat treatment on the corrosion behavior of K-claddings was also examined. Corrosion tests were carried out in the conditions of 360 .deg. C pure water, PWR-simulating loop and 400 .deg. C steam, From the results of the corrosion tests, it was found that the corrosion resistance of K-claddings is superior to those of Zry4 and A claddings and K6 showed a better corrosion resistance than K3. The corrosion behavior of K-cladding was strongly influenced by the final annealing rather than the intermediate annealing, and the corrosion resistance increased with decreasing the final annealing temperature

Corrosion control. 2. ed.

International Nuclear Information System (INIS)

Bradford, S.A.

2001-01-01

The purpose of this text is to train engineers and technologists not just to understand corrosion but to control it. Materials selection, coatings, chemical inhibitors, cathodic and anodic protection, and equipment design are covered in separate chapters. High-temperature oxidation is discussed in the final two chapters ne on oxidation theory and one on controlling oxidation by alloying and with coatings. This book treats corrosion and high-temperature oxidation separately. Corrosion is divided into three groups: (1) chemical dissolution including uniform attack, (2) electrochemical corrosion from either metallurgical or environmental cells, and (3) stress-assisted corrosion. Corrosion is logically grouped according to mechanisms rather than arbitrarily separated into different types of corrosion as if they were unrelated. For those university students and industry personnel who approach corrosion theory very hesitantly, this text will present the electrochemical reactions responsible for corrosion summed up in only five simple half-cell reactions. When these are combined on a polarization diagram, which is also explained in detail, the electrochemical processes become obvious. For those who want a text stripped bare of electrochemical theory, several noted sections can be omitted without loss of continuity. However, the author has presented the material in such a manner that these sections are not beyond the abilities of any high school graduate who is interested in technology

Corrosion in the oil industry

Energy Technology Data Exchange (ETDEWEB)

Brondel, D [Sedco Forex, Montrouge (France); Edwards, R [Schlumberger Well Services, Columbus, OH (United States); Hayman, A [Etudes et Productions Schlumberger, Clamart (France); Hill, D [Schlumberger Dowell, Tulsa, OK (United States); Mehta, S [Schlumberger Dowell, St. Austell (United Kingdom); Semerad, T [Mobil Oil Indonesia, Inc., Sumatra (Indonesia)

1994-04-01

Corrosion costs the oil industry billions of dollars a year, a fact that makes the role of the corrosion engineer an increasingly important one. Attention is paid to how corrosion affects every aspect of exploration and production, from offshore rigs to casing. Also the role of corrosion agents such as drilling and production fluids is reviewed. Methods of control and techniques to monitor corrosion are discussed, along with an explanation of the chemical causes of corrosion. 21 figs., 32 refs.

Phytochemicals as Green Corrosion Inhibitors in Various Corrosive ...

African Journals Online (AJOL)

There is an intensive effort underway to develop new plant origin corrosion inhibitors for metal subjected to various environmental conditions. These efforts have been motivated by the desire to replace toxic inhibitors used for mitigation of corrosion of various metals and alloys in aqueous solutions. Plants represent a class ...

Monitoring Microbially Influenced Corrosion

DEFF Research Database (Denmark)

Hilbert, Lisbeth Rischel

and diffusional effects and unreliable corrosion rates, when biofilm and ferrous sulphide corrosion products cover the steel surface. Corrosion rates can be overestimated by a factor of 10 to 100 by electrochemical techniques. Weight loss coupons and ER are recommended as necessary basic monitoring techniques......Abstract Microbially influenced corrosion (MIC) of carbon steel may occur in media with microbiological activity of especially sulphate-reducing bacteria (SRB). The applicability and reliability of a number of corrosion monitoring techniques for monitoring MIC has been evaluated in experiments....... EIS might be used for detection of MIC as the appearance of very large capacitances can be attributed to the combined ferrous sulphide and biofilm formation. Capacitance correlates directly with sulphide concentration in sterile sulphide media. Keywords: Corrosion monitoring, carbon steel, MIC, SRB...

SRB seawater corrosion project

Science.gov (United States)

Bozack, M. J.

1991-01-01

The corrosion behavior of 2219 aluminum when exposed to seawater was characterized. Controlled corrosion experiments at three different temperatures (30, 60 and 100 C) and two different environments (seawater and 3.5 percent salt solution) were designed to elucidate the initial stages in the corrosion process. It was found that 2219 aluminum is an active catalytic surface for growth of Al2O3, NaCl, and MgO. Formation of Al2O3 is favored at lower temperatures, while MgO is favored at higher temperatures. Visible corrosion products are formed within 30 minutes after seawater exposure. Corrosion characteristics in 3.5 percent salt solution are different than corrosion in seawater. Techniques utilized were: (1) scanning electron microscopy, (2) energy dispersive x-ray spectroscopy, and (3) Auger electron spectroscopy.

Corrosion of circulating water pipings in thermal and nuclear power stations and corrosion prevention measures

International Nuclear Information System (INIS)

Hachiya, Minoru

1982-01-01

In the age of energy conservation at present, the power generation facilities have been examined from the viewpoint of performance, endurance and economy, and in particular, the prevention of the loss due to the corrosion of various facilities is one of most important problems. Since circulating water pipings are in contact with sea water and soil, the peculiar corrosion phenomena are brought about on their external and internal surfaces. Namely, the pitting corrosion due to the environment of soil quality difference, the defects of coating and the contact with reinforcing bars in concrete occurs on the external surface, and the overall corrosion due to the increase of flow velocity and the pitting corrosion due to the defects of coating, the contact with different kinds of metals and the gap in corrosion-resistant steel occur on the internal surface. As the measures for corrosion prevention, corrosion-preventive coating and electric corrosion prevention are applied. The principle, the potential and current density, the system, the design procedure and the examples of application of electric corrosion prevention are described. (Kako, I.)

Improvement of physical and chemical properties of concrete with brazilian silica rice husk (SRH La mejora de propiedades físicas y químicas de hormigón con silice de cáscara de arroz (SRH brasileña

Directory of Open Access Journals (Sweden)

Fernanda Giannotti da Silva

2008-04-01

Full Text Available The use of industrial and agricultural waste substitutions for Portland cement has greatly contributed to sustainable development practices. The increase in cement demand will be met by the use of supplementary cementing materials, in order to minimize the clinker consumption. In this study, the effects of silica extracted from rice husk (SRH as a partial replacement of cement in concretes with low water/binder are reported. The properties investigated include compressive strength, splitting tensile strength, water absorption by immersion, water absorption by capillarity and resistance to chloride ion penetration. The research indicates that SRH is an effective mineral addition for designing durable concrete presenting an optimal performance when the replacement ratio of Portland cement is around 10%El uso de desechos industriales y agrícolas como segmento en la producción de cemento Portland ha contribuido de manera importante en la práctica de desarrollo sustentable. El aumento en la demanda de cemento coincide con el uso de materiales aglomerantes suplementarios para minimizar el consumo de clinker. En este estudio, se informan los efectos de la sustitución parcial de cemento Portland por sílice extraído de la cascara de arroz (SRH en hormigones con baja relación agua/materiales cementicios. Las propiedades investigadas incluyen resistencia a la compresión, resistencia a la tracción, absorción de agua por inmersión, absorción de agua por capilaridad y resistencia a la penetración de iones de cloruro. La investigación indica que SRH es una adición mineral eficaz para el diseño de hormigones durables que presenta una actuación óptima cuando la proporción del reemplazo de cemento de Portland está alrededor de 10%

Aplicaciones de la tecnologia de control termico y de madurez del concreto en Colombia

OpenAIRE

Quimbay Herrera, Rodrigo

2009-01-01

La Tecnología del control térmico y de madurez del concreto (TCTM) tiene un potencial muy amplio en la industria del cemento y del concreto en Colombia, tanto por sus múltiples aplicaciones en los procesos de control de calidad en obra (instrumentación de elementos, control de probetas), como en el control de calidad de recepción en planta para la materia prima (control en tiempo real del cemento). Igualmente, en el control de producción de las diferentes mezclas (e...

Influencia de las características del relleno mineral en la resistencia de una mezcla asfáltica

OpenAIRE

Reyes-Ortiz, O. J. (Oscar Javier); Rincón, J. F. (John Fredy)

2009-01-01

El objetivo principal de esta investigación fue determinar el efecto en la resistencia a tracción indirecta de reemplazar el relleno mineral por cemento, cal y ceniza volante con diferentes porcentajes. El estudio se inició con la caracterización de los materiales (agregados, asfaltos, cal, cemento y ceniza volante), seguido de la determinación del porcentaje óptimo de asfalto mediante el método Marshall. Se seleccionaron para el estudio la granulometría MD10 y el asfalto con penetración 60/7...

Early and late hydration of supersulphated cements of blast furnace slag with fluorgypsum

Directory of Open Access Journals (Sweden)

Bazaldúa-Medellín, M. E.

2015-03-01

Full Text Available The hydration, strength development and composition of hydration products of supersulphated cements were characterized from the first 48 hours up to 360 days. Two compositions of 80% Blast furnace slag, 10–15% Fluorgypsum and 10–5% Portland cement were cured in dry and wet conditions. The main hydration products were ettringite and C-S-H since the first hours and up to 360 days as evidenced by X-ray diffraction, thermal analysis and electron microscopy. The strength was favored by higher fluorgypsum contents and lower Portland cement contents. These cements generated heats of hydration of 40–57 KJ/Kg after 28 hours, which are lower than portland cement.Se realizó la caracterización de la hidratación, desarrollo de resistencia y la composición de los productos de hidratación de los cementos supersulfatados durante las primeras 48 horas y hasta 360 días. Se estudiaron dos composiciones de 80% de Escoria de alto horno, 10–15% de Fluoryeso y 10–5% de Cemento portland, se curaron en condiciones secas y húmedas. Los principales productos de hidratación fueron etringita y C-S-H desde las primeras horas y hasta 360 días, como se evidenció por difracción de rayos X, análisis térmico y microscopía electrónica de barrido. La resistencia se favoreció con mayor contenido de fluoryeso y bajos contenidos de cemento portland. Estos cementos generaron calores de hidratación de 40–57 KJ/Kg después de 28 horas, los cuales resultan más bajos que los generados por el cemento portland.

Scanning electron microscopic observations of fibrous structure of cemento-dentinal junction in healthy teeth.

Science.gov (United States)

Pratebha, B; Jaikumar, N D; Sudhakar, R

2014-01-01

The cemento-dentinal junction (CDJ) is a structural and biologic link between cementum and dentin present in the roots of teeth. Conflicting reports about the origin, structure and composition of this layer are present in literature. The width of this junctional tissue is reported to be about 2-4 μm with adhesion of cementum and dentin by proteoglycans and by collagen fiber intermingling. The objective of this study is to observe and report the fibrous architecture of the CDJ of healthy tooth roots. A total of 15 healthy teeth samples were collected, sectioned into halves, demineralized in 5% ethylenediaminetetraacetic acid, processed using NaOH maceration technique and observed under a scanning electron microscope. The CDJ appeared to be a fibril poor groove with a width of 2-4 µm. Few areas of collagen fiber intermingling could be appreciated. A detailed observation of these tissues has been presented.

Mobile evaporator corrosion test results

International Nuclear Information System (INIS)

Rozeveld, A.; Chamberlain, D.B.

1997-05-01

Laboratory corrosion tests were conducted on eight candidates to select a durable and cost-effective alloy for use in mobile evaporators to process radioactive waste solutions. Based on an extensive literature survey of corrosion data, three stainless steel alloys (304L, 316L, AL-6XN), four nickel-based alloys (825, 625, 690, G-30), and titanium were selected for testing. The corrosion tests included vapor phase, liquid junction (interface), liquid immersion, and crevice corrosion tests on plain and welded samples of candidate materials. Tests were conducted at 80 degrees C for 45 days in two different test solutions: a nitric acid solution. to simulate evaporator conditions during the processing of the cesium ion-exchange eluant and a highly alkaline sodium hydroxide solution to simulate the composition of Tank 241-AW-101 during evaporation. All of the alloys exhibited excellent corrosion resistance in the alkaline test solution. Corrosion rates were very low and localized corrosion was not observed. Results from the nitric acid tests showed that only 316L stainless steel did not meet our performance criteria. The 316L welded interface and crevice specimens had rates of 22.2 mpy and 21.8 mpy, respectively, which exceeds the maximum corrosion rate of 20 mpy. The other welded samples had about the same corrosion resistance as the plain samples. None of the welded samples showed preferential weld or heat-affected zone (HAZ) attack. Vapor corrosion was negligible for all alloys. All of the alloys except 316L exhibited either open-quotes satisfactoryclose quotes (2-20 mpy) or open-quotes excellentclose quotes (<2 mpy) corrosion resistance as defined by National Association of Corrosion Engineers. However, many of the alloys experienced intergranular corrosion in the nitric acid test solution, which could indicate a susceptibility to stress corrosion cracking (SCC) in this environment

The corrosion and corrosion mechanical properties evaluation for the LBB concept in VVERs

Energy Technology Data Exchange (ETDEWEB)

Ruscak, M.; Chvatal, P.; Karnik, D.

1997-04-01

One of the conditions required for Leak Before Break application is the verification that the influence of corrosion environment on the material of the component can be neglected. Both the general corrosion and/or the initiation and, growth of corrosion-mechanical cracks must not cause the degradation. The primary piping in the VVER nuclear power plant is made from austenitic steels (VVER 440) and low alloy steels protected with the austenitic cladding (VVER 1000). Inspection of the base metal and heterogeneous weldments from the VVER 440 showed that the crack growth rates are below 10 m/s if a low oxygen level is kept in the primary environment. No intergranular cracking was observed in low and high oxygen water after any type of testing, with constant or periodic loading. In the framework of the LBB assessment of the VVER 1000, the corrosion and corrosion mechanical properties were also evaluated. The corrosion and corrosion mechanical testing was oriented predominantly to three types of tests: stress corrosion cracking tests corrosion fatigue tests evaluation of the resistance against corrosion damage. In this paper, the methods used for these tests are described and the materials are compared from the point of view of response on static and periodic mechanical stress on the low alloyed steel 10GN2WA and weld metal exposed in the primary circuit environment. The slow strain rate tests and static loading of both C-rings and CT specimens were performed in order to assess the stress corrosion cracking characteristics. Cyclic loading of CT specimens was done to evaluate the kinetics of the crack growth under periodical loading. Results are shown to illustrate the approaches used. The data obtained were evaluated also from the point of view of comparison of the influence of different structure on the stress corrosion cracking appearance. The results obtained for the base metal and weld metal of the piping are presented here.

An evaluation of corrosion resistant alloys by field corrosion test in Japanese refuse incineration plants

International Nuclear Information System (INIS)

Kawahara, Yuuzou; Nakamura, Masanori; Shibuya, Eiichi; Yukawa, Kenichi

1995-01-01

As the first step for development of the corrosion resistant superheater tube materials of 500 C, 100 ata used in high efficient waste-to-energy plants, field corrosion tests of six conventional alloys were carried out at metal temperatures of 450 C and 550 C for 700 and 3,000 hours in four typical Japanese waste incineration plants. The test results indicate that austenitic alloys containing approximately 80 wt% [Cr+Ni] show excellent corrosion resistance. When the corrosive environment is severe, intergranular corrosion of 40∼200 microm depth occurs in stainless steel and high alloyed materials. It is confirmed quantitatively that corrosion behavior is influenced by environmental corrosion factors such as Cl concentration and thickness of deposits on tube surface, metal temperature, and flue gas temperature. The excellent corrosion resistance of high [Cr+Ni+Mo] alloys such as Alloy 625 is explained by the stability of its protective oxide, such that the time dependence of corrosion nearly obeys the parabolic rate law

Importance of the Microscopy of the Clinker

Directory of Open Access Journals (Sweden)

Calleja, J.

1972-09-01

Full Text Available Not availableLa organización por parte del Instituto de estos Cursos como el que hoy comienza no es nueva. Data nada menos que de 1951, en los albores del Centro, fecha en que se desarrolló el Primer Curso para Auxiliares de Laboratorio y Control en la Industria del Cemento, de eficacia tal que hubo de ser repetido, previa su actualización, en 1955. Han seguido después otros de iniciación y adiestramiento en los ensayos del Nuevo Pliego de Conglomerantes en 1961 y en 1964, de Auxiliares de Obra, sobre Fluorescencia y Difracción de Rayos X, sobre Suelo-cemento, sobre Análisis por Fotometría de Llama y Absorción Atómica, aparte de los organizados para graduados hispanoamericanos.

Análisis clínico, radiológico e histológico de los fibromas cemento-osificantes de los maxilares Clinical, radiological and histological analysis of the cemento-ossifying fibromas of the maxilla

Directory of Open Access Journals (Sweden)

L. Domínguez Cuadrado

2004-02-01

Full Text Available Introducción. El fibroma cemento-osificante (FCO en una neoplasia fibro-ósea benigna, de estirpe no odontogénica, más frecuente en mujeres entre la 3ª y 4ª décadas de la vida y que se localiza preferentemente en la región molar o premolar mandibular. Objetivos. Analizar las características clínicas, radiológicas e histológicas del fibroma cemento-osificante (FCO y su controvertida clasificación. Evaluar las lesiones fibro-óseas con las que es necesario realizar un diagnóstico diferencial para llevar a cabo un tratamiento adecuado. Material y método. Se ha realizado un estudio retrospectivo durante el periodo de 1999-2002 de 10 pacientes con FCO, valorando la edad, sexo, antecedentes personales, sintomatología, localización y características radiográficas e histológicas de la lesión. En todos los pacientes se realizó una extirpación local del tumor y un seguimiento mínimo de seis meses tras la cirugía con controles clínicos y radiográficos. Resultados. De los pacientes estudiados 7 eran mujeres y 3 varones, con edades comprendidas entre los 26 y 70 años. En la mayoría de los casos la lesión estaba localizada en el sector posterior mandibular y era asintomática. En la exploración física el hallazgo más frecuente fue un abombamiento de la cortical ósea. Radiológicamente se evidenciaba un patron mixto (radiolúcido-radiopaco que en el análisis histológico correspondía a un estroma fibroso con depósitos calcificados trabeculares y/o esferoidales que recordaban respectivamente al hueso y/o cemento. El tratamiento definitivo consistió en la extirpación local de la lesión y curetaje, sin observarse ninguna recidiva durante el periodo de seguimiento. Conclusión. El FCO suele ser una lesión asintomática que radiográficamente se presenta como una lesión delimitada, de patrón mixto (radiolúcido-radiopaco, que no afecta a los ápices dentarios. Debe realizarse un diagnóstico diferencial con otras lesiones

Modelling reinforcement corrosion in concrete

DEFF Research Database (Denmark)

Michel, Alexander; Geiker, Mette Rica; Stang, Henrik

2012-01-01

A physio-chemical model for the simulation of reinforcement corrosion in concrete struc-tures was developed. The model allows for simulation of initiation and subsequent propaga-tion of reinforcement corrosion. Corrosion is assumed to be initiated once a defined critical chloride threshold......, a numerical example is pre-sented, that illustrates the formation of corrosion cells as well as propagation of corrosion in a reinforced concrete structure....

Hydraulic activity of belite cement from class C coal fly ash. Effect of curing and admixtures

Directory of Open Access Journals (Sweden)

Guerrero, A.

2006-09-01

Full Text Available The effect of curing method and a water-reducing additive on the hydraulic activity of high lime content (ASTM type C fly ash belite cement (FABC-2-W is reported. A class C fly ash was subjected to hydrothermal treatment and subsequent calcination to synthesize FABC. Hydraulic activity was evaluated in the cement paste over 180 days from the physically bound water content as determined by thermogravimetric analysis and the degree of hydration, in turn found with X-ray diffraction (XRD analysis. Mechanical strength, porosity and pore size distribution were also studied in equivalent mortar samples.En este trabajo se discute la influencia del tipo de curado y de un aditivo reductor de la demanda de agua en la actividad hidráulica de un cemento belítico de cenizas volantes de alto contenido en cal denominado (CBCV-2-A. Este cemento ha sido sintetizado por una ruta húmeda hidrotermal con posterior calcinación, empleando ceniza volante de alto contenido en cal (ASTM tipo C como materia prima. La actividad hidráulica se ha estudiado en la pasta de cemento, durante un periodo de 180 días, por medio del contenido de agua combinada, determinada por análisis termogravimétrico, y el grado de hidratación por difracción de rayos X (DRX. La resistencia mecánica y la porosidad total y distribución de tamaño de poro se han estudiado en probetas equivalentes de mortero

Understanding corrosion via corrosion product characterization: II. Role of alloying elements in improving the corrosion resistance of Zn-Al-Mg coatings on steel

International Nuclear Information System (INIS)

Volovitch, P.; Vu, T.N.; Allely, C.; Abdel Aal, A.; Ogle, K.

2011-01-01

Highlights: → Origins of better corrosion resistance of ZnAlMg coatings than galvanized steel. → Comparative study of corrosion products formed on ZnAlMg, ZnMg and Zn coatings. → Modeling of dissolution and precipitation stages of corrosion. → At early stages Mg stabilizes protective zinc basic salts during dry-wet cycling. → At later stages Al dissolves at high pH forming protective layered double hydroxides. - Abstract: Corrosion products are identified on Zn, ZnMg and ZnAlMg coatings in cyclic corrosion tests with NaCl or Na 2 SO 4 containing atmospheres. For Mg-containing alloys the improved corrosion resistance is achieved by stabilization of protective simonkolleite and zinc hydroxysulfate. At later stages, the formation of layered double hydroxides (LDH) is observed for ZnAlMg. According to thermodynamic modeling, Mg 2+ ions bind the excess of carbonate or sulfate anions preventing the formation of soluble or less-protective products. A preferential dissolution of Zn and Mg at initial stages of corrosion is confirmed by in situ dissolution measurement. The physicochemical properties of different corrosion products are compared.

Modelling of Corrosion Cracks

DEFF Research Database (Denmark)

Thoft-Christensen, Palle

Modelling of corrosion cracking of reinforced concrete structures is complicated as a great number of uncertain factors are involved. To get a reliable modelling a physical and mechanical understanding of the process behind corrosion in needed.......Modelling of corrosion cracking of reinforced concrete structures is complicated as a great number of uncertain factors are involved. To get a reliable modelling a physical and mechanical understanding of the process behind corrosion in needed....

Estudio de la hidratación de pastas de cemento adicionadas con catalizador de craqueo catalítico usado (FCC de una refinería colombiana

Directory of Open Access Journals (Sweden)

Jenny Johanna Trochez

2010-01-01

Full Text Available En este artículo se analiza el efecto de la incorporación de un residuo industrial de una refinería de petróleo colombiana, conocido como catalizador de craqueo catalítico usado (FCC, en el proceso de hidratación de pastas cementicias. Para tal efecto, se prepararon pastas de cemento Pórtland ordinario (OPC adicionadas en porcentajes del 10 y 20% de FCC como reemplazo de la cantidad de cemento. La reactividad puzolánica del material y el tipo de productos de hidratación se determinó mediante difracción de rayos X (DRX y análisis termogravimétrico (TG/DTG. Adicionalmente, se determinó el calor de hidratación liberado con base en la norma ASTM C186. Los resultados indican que el proceso de hidratación de pastas adicionadas con FCC es altamente exotérmico como consecuencia de su actividad puzolánica a cortas edades. Las fases principales presentes en el proceso de hidratación de las pastas adicionadas con FCC fueron CSH, CAH y CASH, productos similares a los obtenidos en pastas adicionadas con metacaolín.

Exposure testing of fasteners in preservative treated wood: Gravimetric corrosion rates and corrosion product analyses

Energy Technology Data Exchange (ETDEWEB)

Zelinka, Samuel L., E-mail: szelinka@fs.fed.u [USDA Forest Products Laboratory, One Gifford Pinchot Drive, Madison, WI 53726 (United States); Sichel, Rebecca J. [College of Engineering, University of Wisconsin, Madison, WI 53706 (United States); Stone, Donald S. [Department of Materials Science and Engineering, College of Engineering, University of Wisconsin, Madison, WI 53706 (United States)

2010-12-15

Research highlights: {yields} The composition of the corrosion products was similar for the nail head and shank. {yields} Reduced copper was not detected on any of the fasteners. {yields} Measured corrosion rates were between 1 and 35 {mu}m year{sup -1}. - Abstract: Research was conducted to determine the corrosion rates of metals in preservative treated wood and also understand the mechanism of metal corrosion in treated wood. Steel and hot-dip galvanized steel fasteners were embedded in wood treated with one of six preservative treatments and exposed to 27 {sup o}C at 100% relative humidity for 1 year. The corrosion rate was determined gravimetrically and the corrosion products were analyzed with scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. Although the accepted mechanism of corrosion in treated wood involves the reduction of cupric ions from the wood preservative, no reduced copper was found on the corrosion surfaces. The galvanized corrosion products contained sulfates, whereas the steel corrosion products consisted of iron oxides and hydroxides. The possible implications and limitations of this research on fasteners used in building applications are discussed.

Management of Reinforcement Corrosion

DEFF Research Database (Denmark)

Küter, André; Geiker, Mette Rica; Møller, Per

Reinforcement corrosion is the most important cause for deterioration of reinforced concrete structures, both with regard to costs and consequences. Thermodynamically consistent descriptions of corrosion mechanisms are expected to allow the development of innovative concepts for the management...... of reinforcement corrosion....

Microbiologically induced corrosion

International Nuclear Information System (INIS)

Stein, A.A.

1988-01-01

Biological attack is a problem that can affect all metallic materials in a variety of environments and systems. In the power industry, corrosion studies have focused on condensers and service water systems where slime, barnacles, clams, and other macro-organisms are easily detected. Efforts have been made to eliminate the effect of these organisms through the use of chlorination, backflushing, organic coating, or thermal shock. The objective is to maintain component performance by eliminating biofouling and reducing metallic corrosion. Recently, corrosion of power plant components by micro-organisms (bacteria) has been identified even in very clean systems. A system's first exposure to microbiologically induced corrosion (MIC) occurs during its first exposure to an aqueous environment, such as during hydrotest or wet layup. Corrosion of buried pipelines by sulfate-reducing bacteria has been studied by the petrochemical industry for years. This paper discusses various methods of diagnosing, monitoring, and controlling MIC in a variety of systems, as well as indicates areas where further study is needed

CORROSION RATE OF STEELS DX51D AND S220GD IN DIFFERENT CORROSION ENVIRONMENT

Directory of Open Access Journals (Sweden)

Alina Crina CIUBOTARIU

2016-06-01

Full Text Available Corrosion in the marine environment is an important issue because the costs causes by marine corrosion increased year upon year. It is necessary a correctly approach to materials selection, protection and corrosion control to reduce this burden of wasted materials, wasted energy and wasted money. Many different types of corrosion attack can be observed to structures, ships and other equipment used in sea water service. Shipping containers are exposed to various corrosive mediums like as airborne salt, industrial pollutants, rain and saltwater. Transport damage during loading onto and unloading off trucks, train beds and ships breaches the paint coating which further contributes to corrosion. The result is shortened container life and high costs for container repair or replacement. The paper intends to evaluate, by gravimetric method, the corrosion rate and corrosion penetration rate of two types of carbon steel DX51D and S220GD. Carbon steel DX51D and hot-dip galvanized steel S220GD are used in marine and industrial applications for buildings cargo vessels, container ships and oil tankers. For testing it was used different corrosive environments: 5% NaOH solution; 5% HCL solution and 0.5M NaCl solution. The samples were immersed in 400mL of testing solution for exposure period of 28 days. Periodically at 3 days, 7 days, 14 days, 21 days and 28 days was measured de mass loss and evaluate the corrosion rate and corrosion stability coefficient. The steel DX51D was stable in 5% NaOH solution for 28 days, the values of corrosion stability coefficient was 7 after 3 days and 6 after 28 days of immersion in corrosive medium. In 5% HCL solution steels DX51D and S220GD was completely corroded in 21 days with a corrosion stability coefficient equal with 9 for 7 days and 8 for 21 days of immersion in corrosive solution. It was observed a good resistance for 3 days in 0.5M NaCl solution with a corrosion stability coefficient equal with 5, but after that

General Corrosion and Localized Corrosion of the Drip Shield

Energy Technology Data Exchange (ETDEWEB)

F. Hua

2004-09-16

The repository design includes a drip shield (BSC 2004 [DIRS 168489]) that provides protection for the waste package both as a barrier to seepage water contact and a physical barrier to potential rockfall. The purpose of the process-level models developed in this report is to model dry oxidation, general corrosion, and localized corrosion of the drip shield plate material, which is made of Ti Grade 7. This document is prepared according to ''Technical Work Plan For: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package'' (BSC 2004 [DIRS 171583]). The models developed in this report are used by the waste package degradation analyses for TSPA-LA and serve as a basis to determine the performance of the drip shield. The drip shield may suffer from other forms of failure such as the hydrogen induced cracking (HIC) or stress corrosion cracking (SCC), or both. Stress corrosion cracking of the drip shield material is discussed in ''Stress Corrosion Cracking of the Drip Shield, the Waste Package Outer Barrier, and the Stainless Steel Structural Material'' (BSC 2004 [DIRS 169985]). Hydrogen induced cracking of the drip shield material is discussed in ''Hydrogen Induced Cracking of Drip Shield'' (BSC 2004 [DIRS 169847]).

General Corrosion and Localized Corrosion of the Drip Shield

International Nuclear Information System (INIS)

F. Hua

2004-01-01

The repository design includes a drip shield (BSC 2004 [DIRS 168489]) that provides protection for the waste package both as a barrier to seepage water contact and a physical barrier to potential rockfall. The purpose of the process-level models developed in this report is to model dry oxidation, general corrosion, and localized corrosion of the drip shield plate material, which is made of Ti Grade 7. This document is prepared according to ''Technical Work Plan For: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package'' (BSC 2004 [DIRS 171583]). The models developed in this report are used by the waste package degradation analyses for TSPA-LA and serve as a basis to determine the performance of the drip shield. The drip shield may suffer from other forms of failure such as the hydrogen induced cracking (HIC) or stress corrosion cracking (SCC), or both. Stress corrosion cracking of the drip shield material is discussed in ''Stress Corrosion Cracking of the Drip Shield, the Waste Package Outer Barrier, and the Stainless Steel Structural Material'' (BSC 2004 [DIRS 169985]). Hydrogen induced cracking of the drip shield material is discussed in ''Hydrogen Induced Cracking of Drip Shield'' (BSC 2004 [DIRS 169847])

Misdiagnosis of florid cemento-osseous dysplasia leading to unnecessary root canal treatment: a case report.

Science.gov (United States)

Huh, Jong-Ki; Shin, Su-Jung

2013-08-01

This case report demonstrates an unnecessary endodontic treatment of teeth with florid cemento-osseous dysplasia (FCOD) due to a misdiagnosis as periapical pathosis and emphasizes the importance of correct diagnosis to avoid unnecessary treatment. A 30-year-old woman was referred to our institution for apicoectomies of the mandibular left canine and both the lateral incisors. The periapical lesions associated with these teeth had failed to resolve after root canal treatment over a 3-year period. Radiographic examinations revealed multiple lesions on the right canine, the second premolar, and both first molars as well as the anterior region of the mandible. Based on clinical, radiographic and histological evaluations, the patient condition was diagnosed as FCOD. The patient has been monitored for 2 years. To avoid unnecessary invasive treatment, accurate diagnosis is essential before treatment is carried out in managing FCOD.

Industrial trial to produce a low clinker, low carbon cement

Directory of Open Access Journals (Sweden)

Vizcaíno-Andrés, L. M.

2015-03-01

Full Text Available A preliminary assessment of conditions for the industrial manufacture of a new cementitious system based on clinker-calcined clay and limestone, developed by the authors, referred as “low carbon cement” is presented. The new cement enables the substitution of more than 50% of the mass of clinker without compromising performance. The paper presents the follow-up of an industrial trial carried out in Cuba to produce 130 tonnes of the new cement at a cement plant. The new material proved to fulfill national standards in applications such as the manufacture of hollow concrete blocks and precast concrete. No major differences either in the rheological or mechanical properties were found when compared with Portland cement. Environmental assessment of the ternary cement was made, which included comparison with other blended cements produced industrially in Cuba. The new cement has proven to contribute to the reduction of above 30% of carbon emissions on cement manufacture.Se presenta la evaluación preliminar de las condiciones de fabricación industrial de un nuevo sistema cementicio a partir del empleo de clínquer; arcillas calcinadas y piedra caliza; desarrollado por los autores; denominado “cemento de bajo carbono”. El nuevo cemento posibilita la reducción de más de un 50% de la masa de clínquer; sin comprometer el comportamiento del material. El presente trabajo presenta el monitoreo de la producción industrial en una planta en Cuba; de 130 t del nuevo cemento. El cemento obtenido cumple con las regulaciones nacionales de calidad y su empleo tiene similar rendimiento que el cemento Pórtland para la producción de bloques y hormigón de 25 MPa. Se realiza el análisis de impacto ambiental del cemento ternario mediante la comparación con otros cementos producidos industrialmente. El nuevo cemento puede contribuir a la reducción de más del 30% de las emisiones de CO2 asociadas a la manufactura de cemento.

Catastrophes caused by corrosion

OpenAIRE

PETROVIC ZORAN C.

2016-01-01

For many years, huge attention has been paid to the problem of corrosion damage and destruction of metallic materials. Experience shows that failures due to corrosion problems are very important, and statistics at the world level shows that the damage resulting from the effects of various forms of corrosion is substantial and that, for example, in industrialized countries it reaches 4-5% of national incomes. Significant funds are determined annually for the prevention and control of corrosion...

An overview of erosion corrosion models and reliability assessment for corrosion defects in piping system

International Nuclear Information System (INIS)

Srividya, A.; Suresh, H.N.; Verma, A.K.; Gopika, V.; Santosh

2006-01-01

Piping systems are part of passive structural elements in power plants. The analysis of the piping systems and their quantification in terms of failure probability is of utmost importance. The piping systems may fail due to various degradation mechanisms like thermal fatigue, erosion-corrosion, stress corrosion cracking and vibration fatigue. On examination of previous results, erosion corrosion was more prevalent and wall thinning is a time dependent phenomenon. The paper is intended to consolidate the work done by various investigators on erosion corrosion in estimating the erosion corrosion rate and reliability predictions. A comparison of various erosion corrosion models is made. The reliability predictions based on remaining strength of corroded pipelines by wall thinning is also attempted. Variables in the limit state functions are modelled using normal distributions and Reliability assessment is carried out using some of the existing failure pressure models. A steady state corrosion rate is assumed to estimate the corrosion defect and First Order Reliability Method (FORM) is used to find the probability of failure associated with corrosion defects over time using the software for Component Reliability evaluation (COMREL). (author)

Corrosion protection and control using nanomaterials

CERN Document Server

Cook, R

2012-01-01

This book covers the use of nanomaterials to prevent corrosion. The first section deals with the fundamentals of corrosion prevention using nanomaterials. Part two includes a series of case studies and applications of nanomaterials for corrosion control.$bCorrosion is an expensive and potentially dangerous problem in many industries. The potential application of different nanostructured materials in corrosion protection, prevention and control is a subject of increasing interest. Corrosion protection and control using nanomaterials explores the potential use of nanotechnology in corrosion control. The book is divided into two parts. Part one looks at the fundamentals of corrosion behaviour and the manufacture of nanocrystalline materials. Chapters discuss the impact of nanotechnology in reducing corrosion cost, and investigate the influence of various factors including thermodynamics, kinetics and grain size on the corrosion behaviour of nanocrystalline materials. There are also chapters on electrodeposition ...

Monitoring and modeling stress corrosion and corrosion fatigue damage in nuclear reactors

International Nuclear Information System (INIS)

Andresen, P.L.; Ford, F.P.; Solomon, H.D.; Taylor, D.F.

1990-01-01

Stress corrosion and corrosion fatigue are significant problems in many industries, causing economic penalties from decreased plant availability and component repair or replacement. In nuclear power reactors, environmental cracking occurs in a wide variety of components, including reactor piping and steam generator tubing, bolting materials and pressure vessels. Life assessment for these components is complicated by the belief that cracking is quite irreproducible. Indeed, for conditions which were once viewed as nominally similar, orders of magnitude variability in crack growth rates are observed for stress corrosion and corrosion fatigue of stainless steels and low-alloy steels in 288 degrees C water. This paper shows that design and life prediction approaches are destined to be overly conservative or to risk environmental failure if life is predicted by quantifying only the effects of mechanical parameters and/or simply ignoring or aggregating environmental and material variabilities. Examples include the Nuclear Regulatory Commission (NRC) disposition line for stress-corrosion cracking of stainless steel in boiling water reactor (BWR) water and the American Society of Mechanical Engineers' Section XI lines for corrosion fatigue

Recognition and Analysis of Corrosion Failure Mechanisms

Directory of Open Access Journals (Sweden)

Steven Suess

2006-02-01

Full Text Available Corrosion has a vast impact on the global and domestic economy, and currently incurs losses of nearly $300 billion annually to the U.S. economy alone. Because of the huge impact of corrosion, it is imperative to have a systematic approach to recognizing and mitigating corrosion problems as soon as possible after they become apparent. A proper failure analysis includes collection of pertinent background data and service history, followed by visual inspection, photographic documentation, material evaluation, data review and conclusion procurement. In analyzing corrosion failures, one must recognize the wide range of common corrosion mechanisms. The features of any corrosion failure give strong clues as to the most likely cause of the corrosion. This article details a proven approach to properly determining the root cause of a failure, and includes pictographic illustrations of the most common corrosion mechanisms, including general corrosion, pitting, galvanic corrosion, dealloying, crevice corrosion, microbiologically-influenced corrosion (MIC, corrosion fatigue, stress corrosion cracking (SCC, intergranular corrosion, fretting, erosion corrosion and hydrogen damage.

Corrosion of PWR steam generators

International Nuclear Information System (INIS)

Garnsey, R.

1979-01-01

Some designs of pressurized water reactor (PWR) steam generators have experienced a variety of corrosion problems which include stress corrosion cracking, tube thinning, pitting, fatigue, erosion-corrosion and support plate corrosion resulting in 'denting'. Large international research programmes have been mounted to investigate the phenomena. The operational experience is reviewed and mechanisms which have been proposed to explain the corrosion damage are presented. The implications for design development and for boiler and feedwater control are discussed. (author)

Archaeological analogs and corrosion; Analogues archeologiques et corrosion

Energy Technology Data Exchange (ETDEWEB)

David, D

2008-07-01

In the framework of the high level and long life radioactive wastes disposal deep underground, the ANDRA built a research program on the material corrosion. In particular they aim to design containers for a very long time storage. Laboratory experiments are in progress and can be completed by the analysis of metallic archaeological objects and their corrosion after hundred years. (A.L.B.)

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

Directory of Open Access Journals (Sweden)

Moreno Arús, Fernando

1975-09-01

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

The Corrosion Inhibition Characteristics of Sodium Nitrite Using an On-line Corrosion Rate Measurement System

International Nuclear Information System (INIS)

Park, Mal-Yong; Kang, Dae-Jin; Moon, Jeon-Soo

2015-01-01

An on-line corrosion rate measurement system was developed using a personal computer, a data acquisition board and program, and a 2-electrode corrosion probe. Reliability of the developed system was confirmed with through comparison test. With this system, the effect of sodium nitrite (NaNO 2 ) as a corrosion inhibitor were studied on iron and aluminum brass that were immersed in sodium chloride (NaCl) solution. Corrosion rate was measured based on the linear polarization resistance method. The corrosion rates of aluminum brass and iron in 1% NaCl solutions were measured to be 0.290 mm per year (mmpy) and 0.2134 mmpy, respectively. With the addition of 200 ppm of NO 2 - , the corrosion rates decreased to 0.0470 mmpy and 0.0254 mmpy. The addition of NO 2 - caused a decrease in corrosion rates of both aluminum brass and iron, yet the NO 2 - acted as a more effective corrosion inhibitor for iron. than aluminum brass

Corrosion Engineering.

Science.gov (United States)

White, Charles V.

A description is provided for a Corrosion and Corrosion Control course offered in the Continuing Engineering Education Program at the General Motors Institute (GMI). GMI is a small cooperative engineering school of approximately 2,000 students who alternate between six-week periods of academic study and six weeks of related work experience in…

Some observations on phosphate based corrosion inhibitors in preventing carbon steel corrosion

International Nuclear Information System (INIS)

Anupkumar, B.; Satpathy, K.K.

2000-01-01

Among the various types of phosphonic acid based inhibitors assayed, namely HEDP, ATMP and a commercial corrosion inhibitor (code named Betz), it was found that Betz has the maximum amount of organic phosphate followed by HEDP and ATMP. The corrosion rate studies show that Betz gives the highest inhibition efficiency followed by HEDP and ATMP. This shows that organic phosphate plays a significant role in corrosion protection. However, it was observed that due to synergestic effect, HEDP in the presence of Zn 2+ gave a better corrosion protection than Betz. The results are discussed in the light of available literature. (author)

Corrosion and alteration of materials from the nuclear industry; La Corrosion et l'alteration des materiaux du nucleaire

Energy Technology Data Exchange (ETDEWEB)

Beauvy, M.; Berthoud, G.; Defranceschi, M.; Ducros, G.; Feron, D.; Guerin, Y.; Latge, C.; Limoge, Y.; Madic, C.; Santarini, G.; Seiler, J.M.; Vernaz, E.; Richet, C.

2010-07-01

The control of the corrosion phenomenon is of prime importance for the nuclear industry. The efficiency and the safety of facilities can be affected by this phenomenon. The nuclear industry has to face corrosion for a large variety of materials submitted to various environments. Metallic corrosion operates in the hot and aqueous environment of water reactors which represent the most common reactor type in the world. Progresses made in the control of the corrosion of the different components of these reactors allow to improve their safety. Corrosion is present in the facilities of the back-end of the fuel cycle as well (corrosion in acid environment in fuel reprocessing plants, corrosion of waste containers in disposal and storage facilities, etc). The future nuclear systems will widen even more the range of materials to be studied and the situations in which they will be placed (corrosion by liquid metals or by helium impurities). Very often, corrosion looks like a patchwork of particular cases in its description. The encountered corrosion problems and their study are presented in this book according to chapters representing the main sectors of the nuclear industry and classified with respect to their phenomenology. This monograph illustrates the researches in progress and presents some results of particular importance obtained recently. Content: 1 - Introduction: context, stakes and goals; definition of corrosion; a complex science; corrosion in the nuclear industry; 2 - corrosion in water reactors - phenomenology, mechanisms, remedies: A - uniform corrosion: mechanisms, uniform corrosion of fuel cladding, in-situ measurement of generalized corrosion rate by electrochemical methods, uniform corrosion of nickel alloys, characterization of the passive layer and growth mechanisms, the PACTOLE code - an integrating tool, influence of water chemistry on corrosion and contamination, radiolysis impact on uniform corrosion; B - stress corrosion: stress corrosion cracking

Florid Cemento-osseous Dysplasia: A Case of Misdiagnosis.

Science.gov (United States)

Delai, Débora; Bernardi, Anarela; Felippe, Gabriela Santos; da Silveira Teixeira, Cleonice; Felippe, Wilson Tadeu; Santos Felippe, Mara Cristina

2015-11-01

Florid cemento-osseous dysplasia (FCOD) belongs to the group of fibro-osseous lesions in which normal bone is replaced by fibrous connective tissue and calcified cementum tissue of the avascular type. Among the various types of fibro-osseous lesions, FCOD is one of the most commonly encountered diseases in clinical practice and may involve 3 or 4 of the quadrants. FCOD is located in the periapical regions of teeth, and the lesions are predominantly radiolucent (osteolytic phase), become mixed over time (cementoblast phase), and ultimately become radiopaque (osteogenic phase) with a thin radiolucent peripheral halo. The characteristics of FCOD in the initial stages are similar to those of periapical lesions of inflammatory origin, which may lead to misdiagnosis. A 38-year-old woman sought dental care because of complaints of pain on the right side of her face. A clinical examination revealed no marked alterations; a panoramic radiograph was therefore requested and revealed the presence of radiolucent lesions associated with the periapical regions of some of the lower teeth. Thus, the professional referred the patient for endodontic treatment of the associated teeth with the justification that the lesions were of endodontic origin. However, the endodontist found that the teeth responded positively to a sensitivity test. The initial diagnosis could have resulted in unnecessary root canal treatment, but after careful clinical, radiographic, and tomographic assessments by different professionals, FCOD was diagnosed, conservatively treated, and regularly monitored. It is important that dentists have a basic knowledge of the various injuries that affect the jaw bones to prevent errors in diagnosis and treatment and to promote oral health. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.