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Sample records for cementos por corrosion

  1. Acción del CO2 sobre un cemento portlcnd. II. Estudio por espectroscopia infrarroja

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    Vázquez-Moreno, Tomás

    1977-12-01

    Full Text Available En un artículo anterior (1 se dio cuenta de los trabajos realizados sobre la influencia que ejerce el CO2 puro en las características químicas, físicas y fisicomecánicas de un cemento portland (P-450, fabricado por la industria española, habiendo probado que tanto el cemento anhidro, como el hidratado, experimentan una modificación de la composición química que afecta, en grado distinto, a las propiedades mecánicas consideradas. El estudio de la composición estructural del cemento anhidro e hidratado, así como cuando ambos se someten a la acción del CO2, es de una importancia decisiva para conocer las causas que determinan la variación de sus propiedades.

  2. 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,

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

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    Vázquez-Moreno, Tomás

    1976-06-01

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

  4. ESTUDIO SOBRE PASTAS Y MORTEROS DE CEMENTO PORTLAND CON REEMPLAZO POR LOZA SANITARIA

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    Silvina Zito

    2016-01-01

    Full Text Available En este trabajo se analiza el uso de Loza Sanitaria como reemplazo del cemento portland. Los reemplazos utilizados fueron 8, 24 y 40 % en peso; los ensayos empleados contemplaron la evolución de la hidratación desde los primeros minutos (hasta 48 horas a través de la calori metría , y a partir de los dos días (hasta 28 días por medio de la velocidad de fijación del hidróxido de calcio, el agua químicamente combinada, la resistencia mecánica a flexión y a compresión y la porosidad. Los resultados mostraron que a medida que aum enta el porcentaje de reemplazo, a las primeras edades d el efecto de dilución solapa y se contrapone con el de estimulación física ; y a la edad de 28 días todas las mezclas presentan además de la estimulación física también la química , por la reactividad puzolánica.

  5. ESTUDIO DEL IMPACTO TÉCNICO DE MEZCLAS DE CONCRETO HIDRÁULICO POR LA SUSTITUCIÓN PARCIAL DE CEMENTO POR ZEOLITA

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    I. Miranda Pasos

    2014-06-01

    Full Text Available La industria de la construcción cada vez más consciente de la necesidad de ejecutar obras con materiales que se obtengan y/o utilicen procesos industriales que minimicen la contaminación y, que contribuyan en el comportamiento de un producto como lo es el concreto hidráulico en la construcción, ha estado buscando alternativas de materiales que sustituyan total o parcialmente al cemento por otro cementante que contamine menos en su procesos de obtención y que conserve las propiedades o las mejore. Una alternativa para sustitución parcial del cemento es la zeolita, es un mineral que se obtiene por proceso de excavación y molienda de puzolana. La norma ASTM-618, define a las puzolanas como materiales silíceo o aluminio-silíceo que por sí solo poseen poco a ningún valor cementante, pero cuando se han dividido finamente y en presencia de agua e hidróxido de calcio (Cal reaccionan químicamente a temperatura ambiente para formar cementantes (Miranda, 2008. Recientemente se ha estudiado el efecto de adicionar mineral Cal-Zeolita para la elaboración del concreto, cuyos resultados son favorables al comportamiento mecánico y su durabilidad (Dopico J.J., et al. 2009. Para la elaboración de morteros para recubrimientos al incorporar arenas zeolíticas como sustituto de la arena tradicional (Tiburcio et al. 2008. El presente proyecto evaluó el comportamiento del concreto hidráulico en estado fresco y endurecido al sustituir de manera parcial cemento por zeolita. Se enfocó a la evaluación del comportamiento mecánico como al diseño de la mezcla de concreto hidráulico fabricado con cemento normal y con cemento-zeolita. Tomando en cuenta los resultados obtenidos, la zeolita incorporada en porcentajes entre el 5% y 10 % tiende a valores de resistencias muy cercanos al concreto normal, los modelos obtenidos así lo corroboran, por lo que se puede concluir la factibilidad de sustitución parcial de cemento por zeolita tomando en cuenta el

  6. 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.

  7. Resistencia química del hormigón. X.- Influencia de la adición de escoria a un cemento portland resistente al yeso. Estudio por DRX del sistema cemento 2/escoria-agua potable filtrada

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    Sagrera-Moreno, José Luis

    1981-06-01

    Full Text Available Not available

    En el presente trabajo [continuación de otro en el que se dio cuenta de las variaciones que experimentan las resistencias mecánicas a flexotracción y la evolución de los coeficientes de corrosión de probetas de mortero (1:3 conservadas bajo agua potable filtrada y agua de mar artificial ASTM D 1141-75] se estudia por DRX la composición estructural de las nuevas fases sólidas formadas en los medios de curado y de conservación (agua potable filtrada en donde han estado sumergidas las series testigo de 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 de cemento 2/escoria granulada (vítrea = 85/ /15-65/35-40/60 y 30/70 (en peso, durante 21 días en el primer período y 56-90-180 y 360 días en el segundo, así como la evolución de las fases cristalinas de la fracción enriquecida (cemento hidratado extraída de uno de los prismas de cada serie de probetas de mortero.

  8. Resistencia química del hormigón. IX.- Influencia de la adición de escoria a un cemento portland de alta resistencia inicial. Estudio por DRX del sistema cemento 1/escoria-agua potable filtrada

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    Gaspar-Tébar, Demetrio

    1981-03-01

    Full Text Available Not available

    En el presente trabajo [continuación de otro en el que se dio cuenta de las variaciones que experimentan las resistencias mecánicas a flexotracción y de la evolución de los coeficientes de corrosión de probetas de mortero (1:3 sumergidas en agua potable filtrada y en agua de mar artificial ASTM D 1141-75] se estudia por DRX la composición estructural de las nuevas fases sólidas formadas en los medios de curado y conservación (agua potable filtrada en donde han estado sumergidas las distintas series testigo de probetas de ;mortero (1:3 de 1 X 1 X 6 cm hechas con el cemento 1 de alta resistencia inicial, cemento 1 < > P-550-ARI, y con las mezclas cemento 1/escoria granulada (vítrea = 85/ /15-65/35-40/60 y 30/70 (en peso, durante 21 días en el primer período y 56-90-180 y 360 días en el segundo, así como la evolución de las fases cristalinas de la fracción enriquecida (cemento hidratado extraída de uno de Los prismas de cada serie de probetas de mortero.

  9. Resistencia química del hormigón. XII.- Influencia de la adición de escoria a un cemento portland. Estudio por DRX del sistema cemento 3/escoria-agua potable filtrada

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    Sagrera-Moreno, José Luis

    1981-09-01

    Full Text Available Not available

    En el presente trabajo [continuación de otro en el que se dio cuenta de las variaciones que experimentan las resistencias mecánicas a flexotracción y de la evolución de los coeficientes de corrosión de probetas de mortero (1:3 sumergidas en agua potable filtrad y en agua de mar artificial ASTM D 1141-75] se estudia por DRX la composición estructural de las nuevas fases sólidas formadas en los medios de curado y de conservación (agua potable filtrada, en donde han estado sumergidas las distintas series testigo de probetas de mortero (1:3 de 1 X 1 X 6 cm, hechas con el cemento portland, cemento 3 < > < > P-450, y con las mezclas cemento 3/escoria granulada (vítrea = 85/15-65/35-40/60- y 30/70 (en peso durante 21 días en el primer período y 56-90-180 y 360 días en el segundo, así como la evolución de las fases cristalinas de la fracción enriquecida (cemento hidratado extraída de uno de los prismas de cada serie de probetas de mortero.

  10. Propagación de grietas por fatiga de cementos óseos acrílicos. Influencia de los agentes radiopacos

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    Ginebra, M. P.

    2001-04-01

    Full Text Available In this work the 2,5-diiodo-8-quinolyl methacrylate (IHQM, is proposed as a new radiopaque agent. The addition of the iodine containing methacrylate provided a statistically significant increase in the tensile strength, fracture toughness and ductility, with respect to the barium sulphate containing cement. This effect was attributed to the fact that the use of a radiopaque monomer eliminated the porosity associated to the barium sulphate particles. However, since fatigue resistance is one of the main properties required to ensure a good long-term performance of permanent prostheses, as is the case of acrylic bone cements, it is important to compare the fatigue properties of this new bone cement formulation with the radiolucent and the BaS04 containing bone cements. The results show that the absence of inorganic particles with no matrix adhesion plays a negative role when the fatigue crack propagation is considered.

    En este trabajo se propone el monómero 2,5-diyodo-8-quinolina metacrilato (IHQM como nuevo agente radiopaco. La adición del agente yodado proporciona un aumento en la resistencia a la tracción, en la tenacidad a la fractura y en la ductilidad con respecto al cemento óseo que contiene sulfato de bario como agente radiopaco. Este efecto se atribuye al hecho de que la utilización del monómero radiopaco elimina la porosidad asociada a las partículas de sulfato de bario que presentan una nula adhesión con la matriz polimérica. Sin embargo, debido a que la resistencia a la propagación de grietas por fatiga es una de las principales propiedades requeridas para el buen comportamiento del cemento en servicio a largo plazo, es importante comparar las propiedades de fatiga de esta nueva formulación de cemento óseo con el cemento que contiene BaS04. Los resultados muestran que la ausencia de partículas inorgánicas en el cemento juega un papel negativo en la propagación de grietas por fatiga.

  11. 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 

  12. Determinación del contenido de compuestos de cromo en el cemento portland por espectrofotometría de absorción atómica. Primera parte

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    Gaspar-Tebar, Demetrio

    1976-09-01

    Full Text Available Not availableEn el presente trabajo se da cuenta de un procedimiento para determinar el contenido de compuestos de cromo en el cemento portland por absorción atómica, bien por el método directo o por el de las adiciones patrones. La fusión se realiza con LiBO2 y la eliminación de interferencias por adición de La (III (1%. Para el desarrollo del trabajo ha sido necesario averiguar dicho contenido por espectrofotocolorimetría del complejo formado por reacción del cromo presente en los cementos, una vez pasado a Cr (VI, con la s-difenilcarbacida. Por otra parte se ha estudiado una variación del método propuesto sustituyendo la fusión alcalina con Na2 C03, o con la mezcla Na2CO3-K2CO3, por la fusión con LiBO2 que proporciona resultados menos dispersos y una desviación estándar estimada, una precisión y un coeficiente de variación menores. Si bien la sensibilidad del método colorimétrico es mayor que la del método propuesto de absorción atómica, éste último es más rápido, con una precisión del mismo orden y, además, permite analizar cuantitativamente los compuestos de cromo siguiendo la marcha que normalmente se utiliza para los demás constituyentes del cemento por absorción atómica. Se hace un estudio estadístico, calculando la desviación estándar estimada, la precisión y el coeficiente de variación de los resultados obtenidos en diversos cementos y clínkeres de cemento portland españoles.

  13. 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

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    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)

  14. Determinación del contenido de compuestos de cromo en el cemento portland por espectrofotometría de absorción atómica. Segunda parte

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    Gaspar-Tebar, Demetrio

    1976-12-01

    Full Text Available Not availableEn un trabajo anterior (1 se ha puesto de manifiesto la importancia que tiene conocer el contenido de compuestos de cromo (III y de cromo (VI en el cemento portland, habiendo determinado dicho contenido en diversas 'muestras de distintos cementos, fabricados por la industria española, por espectrofotocolorimetría del complejo coloreado formado en la reacción que tiene lugar entre el cromo (VI y la s-difenilcarbacida, de tal modo que se puedan utilizar como patrones para estudiar y poner a punto un procedimiento rápido y preciso que utiliza la espectrofotometría de absorción atómica, objeto del presente artículo.

  15. 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.

  16. 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

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    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...

  17. 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.

  18. Valorización de Cementos Pacasmayo

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    Peñaranda Huerta, Ricardo Alberto; Salinas Lau, Gerardo Jesús; Vega Gamonal, Gerard Alvaro

    2017-01-01

    Cementos Pacasmayo S.A.A. y sus subsidiarias son los productores, distribuidores y comercializadores de cemento más importante en el norte del Perú, cuenta con 3 plantas de producción en Pacasmayo, Rioja y Piura, con una capacidad de producción total anual de 4,9 millones de TM. Su participación de mercado es aproximadamente el 95% y tienen más de 200 puntos de venta. La valorización por el método de flujos de caja descontados (DCF) tiene como fecha base el 30 de diciembre del 2016. Entre los...

  19. Cemento-ossifying fibroma.

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    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.

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

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    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.

  1. 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.

  2. 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.

  3. 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

  4. Physicochemical changes of cements by ground water corrosion in radioactive waste storage; Evolucion fisicoquimica de los cementos por corrosion de aguas subterraneas en un almacen de desechos radioactivos

    Energy Technology Data Exchange (ETDEWEB)

    Contreras R, A.; Badillo A, V. E.; Robles P, E. F. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Nava E, N. [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas No. 152, Col. San Bartolo Atepehuacan, 07730 Mexico D. F. (Mexico)], e-mail: aida.contreras@inin.gob.mx

    2009-10-15

    Knowing that the behavior of cementations materials based on known hydraulic cement binder is determined essentially by the physical and chemical transformation of cement paste (water + cement) that is, the present study is essentially about the cement paste evolution in contact with aqueous solutions since one of principal risks in systems security are the ground and surface waters, which contribute to alteration of various barriers and represent the main route of radionuclides transport. In this research, cements were hydrated with different relations cement-aqueous solution to different times. The pastes were analyzed by different solid observation techniques XRD and Moessbauer with the purpose of identify phases that form when are in contact with aqueous solutions of similar composition to ground water. The results show a definitive influence of chemical nature of aqueous solution as it encourages the formation of new phases like hydrated calcium silicates, which are the main phases responsible of radionuclides retention in a radioactive waste storage. (Author)

  5. Nuevos usos del cemento

    Directory of Open Access Journals (Sweden)

    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.

  6. Cementos con cenizas volantes

    Directory of Open Access Journals (Sweden)

    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

  7. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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

  10. 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)

  11. 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.

  12. Cemento-ossifying fibroma

    Directory of Open Access Journals (Sweden)

    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.

  13. ESTABILIZACIÓN DEL PIGMENTO AZUL ULTRAMAR EN CEMENTO PÓRTLAND BLANCO

    Directory of Open Access Journals (Sweden)

    JUAN GUILLERMO MORALES RENDÓN

    2008-01-01

    Full Text Available Se prepararon muestras de cemento azul a partir de cemento Pórtland Blanco Tipo III, según Normas Técnicas Colombianas NTC y pigmento Azul Ultramar U-601 adicionado en un 2% en peso del cemento. El cemento se caracterizó químicamente por fluorescencia de rayos X, y físicamente mediante los ensayos típicos según las NTC. Al pigmento y al cemento se les determinaron sus coordenadas cromáticas por espectrofotometría mediante el sistema CIELAB. Se eligieron varios aditivos y adiciones (entre orgánicos, inorgánicos y minerales para ser adicionados al cemento azul en diferentes dosificaciones en peso. Tanto a las muestras de cemento azul sin aditivo como a aquellas con las diferentes dosificaciones de aditivos, se les determinaron sus características físicas de desempeño y coordenadas cromáticas a diferentes edades de curado en agua saturada con cal (1, 3, 7 y 28 días. Adicionalmente se les determinó el color en las mismas edades a especimenes curados a las condiciones ambientales del laboratorio. Se presentó decoloración total en todos aquellos cementos adicionados con aditivos orgánicos, y decoloración parcial en los cementos adicionados con algunos de los aditivos inorgánicos y ciertas adiciones minerales. Tanto los tiempos de fraguado, como las resistencias a la compresión y demás variables de desempeño experimentaron cambios significativos, en algunos casos positivos y en otros negativos, como consecuencia y efecto de las diferentes dosificaciones utilizadas de cada uno de los aditivos.

  14. Valorización de Cementos Pacasmayo S.A.A.

    OpenAIRE

    Cabello Poggi, Marco Antonio; Montalvo Tenicela, José Luis; Vivanco Seminario, José Guillermo

    2017-01-01

    El presente trabajo de investigación tiene por objetivo valorizar la empresa Cementos Pacasmayo y subsidiarias, estimando un precio por acción a diciembre de 2016. La empresa es líder en producción y comercialización de cemento y derivados en la región norte del país, al mantener una participación por encima del 95%, con una demanda que proviene –principalmente- del segmento de la autoconstrucción, seguido por la inversión privada en dicha zona del país, estando en la capacidad de abastecer l...

  15. Influencia del polvo del horno de cemento sobre plantas y animales

    Directory of Open Access Journals (Sweden)

    Pajenkamp, H.

    1963-06-01

    Full Text Available Not availableEl pretendido «polvo de cemento» de los alrededores de las fábricas no es de cemento, sino que se compone, en su mayor parte, de caliza molida muy fina. Es, por tanto, un producto intermedio de la fabricación del cemento. Sería mucho más correcto llamarle «polvo del horno de cemento». Continuamente alegan los agricultores que este «polvo del horno de cemento» es dañino para plantas y animales, y en los últimos años, para probar la validez de tales asertos, se han llevado a cabo numerosas investigaciones científicas para estudiar los efectos de este polvo. Estamos hoy día en posesión de una serie· de trabajos muy completos que dan una idea clara sobre el efecto del polvo del horno de cemento. Los animales domésticos útiles (por ejemplo: corderos, vacas de leche no sufren ningún perjuicio clínico, ninguna deficiencia de su estado general, a pesar de serie administradas grandes dosis de polvo. Los ensayos agrícolas con plantas útiles (avena, trébol, remolacha azucarera, pastos que han sido efectuados durante varios años, han demostrado que ni siquiera cantidades elevadas de polvo provocan perjuicios ni influencias nefastas sobre el crecimiento y sobre la recolección.

  16. Determinación del contenido de escorias en los cementos siderúrgicos

    Directory of Open Access Journals (Sweden)

    Gaspar-Tébar, Demetrio

    1976-06-01

    Full Text Available Not availableLos cementos siderúrgicos son conglomerantes hidráulicos preparados con mezclas muy íntimas constituidas, fundamentalmente, por escoria básica granulada, obtenida de procesos siderúrgicos, clínker de cemento portland y sulfato cálcico en distintas proporciones (1; mezclas que se preparan por molturación conjunta de los componentes mencionados (2 (3 (4. Las mezclas, aún cuando no es recomendable, también se pueden realizar a partir de los componentes molidos por separado.

  17. Las nuevas normas españolas para cemento

    Directory of Open Access Journals (Sweden)

    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.

  18. Capacidad de fijación y adsorción de cloruros en morteros elaborados con distintos cementos

    OpenAIRE

    Villagrán Zaccardi, Yuri Andrés; Matiasich, Cecilia

    2004-01-01

    La retención de iones cloruro por parte de los hidratos del cemento se puede producir por dos mecanismos: por adsorción superficial, principalmente en la fase de silicato hidratado; y por fijación, mayormente en la fase de aluminato hidratado. Este trabajo tiene por objetivo determinar las capacidades de adsorción y de fijación de cloruros en morteros con una misma relación a/c, realizados con distintos cementos (normal, fillerizado, compuesto y de alto horno). El estudio comprende dos series...

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

    OpenAIRE

    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...

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  2. Valorización de Cementos Pacasmayo S.A.A.

    OpenAIRE

    Ortiz Esteban, Luis Francisco

    2016-01-01

    Cementos Pacasmayo es una empresa sólida, líder en el mercado de cemento del Perú, con un desarrollo en infraestructura significativa y estrategias innovadoras que apuntan a un crecimiento importante como empresa. Por ello, se considera que las buenas perspectivas de la economía peruana, la ejecución de importantes proyectos de infraestructura por la gran brecha que existe en el norte del País, la proximidad de unas elecciones en las que todos los candidatos apuntan al desarrollo económico, y...

  3. en cementos el Cairo S.A.

    Directory of Open Access Journals (Sweden)

    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.

  4. 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.

  5. 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...

  6. 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...

  7. 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...

  8. Cement content influence in rebar corrosion in carbonated mortars

    Directory of Open Access Journals (Sweden)

    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

  9. 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.

  10. Fraguado rápido y falso fraguado en los cementos portland

    Directory of Open Access Journals (Sweden)

    Hansen, W. C.

    1962-09-01

    Full Text Available Not availableEste artículo es una revisión de los trabajos y discusiones sobre falso fraguado presentados en el 4.0 Simposium Internacional sobre Química del Cemento. El «falso fraguado» se define como la rigidez producida por la cristalización del yeso en la pasta del cemento, y el «fraguado rápido» como la rigidez motivada por las reacciones del C3A y C4AF con el agua. Se presentan datos o resultados para demostrar que algunos cementos que contienen yeso deshidratado pueden no mostrar falso fraguado hasta que la aireación reduce la velocidad a que el C3A reaccione con SO4Ca. El trabajo también demuestra que algunos cementos pueden desarrollar fraguado rápido por aireación, reduciendo la aptitud del C3S en liberar Ca(OH 2en la solución para controlar las reacciones de C3A y C4AF con el agua.

  11. 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, ...

  12. 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 ...

  13. 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.

  14. Análisis cuantitativo por difracción de rayos X de cuarzo-alfa en una matriz de cemento portland anhidro con equipos Philips modelo PW-1710 y PW-1700

    Directory of Open Access Journals (Sweden)

    Sagrera Moreno, J. L.

    1985-12-01

    Full Text Available This article, explains the necessary steps to obtained a quartz-low quantitative analysis in an anhydrous Portland cement matrix, by means of a simple addition of a little quantity of Corydon to the sample and applying a simple mathematical formula which gives directly the crystalline compound percentage which determination is required. With this method the labour of preparation samples with internal standard, necessary to obtain a straight line, is eliminated. The need of having a pure sample of the compound which is to be analyzed is also excluded. The method is simple and rapid, offering an acceptable precision in the quantitative crystalline compounds determination.

    En el presente artículo se explican los pasos necesarios para realizar un análisis cuantitativo de cuarzo-alfa en una matriz de cemento portland anhidro, mediante la simple adición de una pequeña cantidad de CORINDÓN a la muestra y la aplicación de una sencilla fórmula matemática (1 que directamente proporciona el porcentaje del compuesto cristalino que se quiere determinar. Con este método se elimina la laboriosa preparación de muestras con patrón interno, necesarias para obtener una curva de calibrado. Además se elimina la necesidad de poseer muestra pura del componente que se quiere analizar. El método es sencillo y rápido, dando una precisión aceptable en las determinaciones cuantitativas de compuestos cristalinos.

  15. Effect of sewage sludge ash (SSA on the mechanical performance and corrosion levels of reinforced Portland cement mortars

    Directory of Open Access Journals (Sweden)

    Andión, L. G.ª

    2006-06-01

    Full Text Available The article describes a study conducted to determinecorrosion in reinforcement embedded in Portland cement(PC mortars with different percentages of sewage sludgeash (SSA admixtures. The polarization resistancetechnique was used to determine the steel corrosion rate(Icorr in the test specimens. The samples were subjectedto different environmental conditions and aggressiveagents: 100% relative humidity (RH, accelerated carbonationat 70% RH and seawater immersion. Portlandcement was partially substituted for SSA in the mixes atrates of 0, 10, 20, 30 and 60% (by mass to make thedifferent mortars. The results show that where cementwas replaced by SSA at rates of up to 10% by mass,mortar corrosion performance was comparable to thebehaviour observed in SSA-free mortars (control mortar:0% SSA. Data for higher rates are also shown. From themechanical standpoint, SSA exhibited moderate pozzolanicactivity and the best performance when SSA wasadded at a rate of 10% to mixes with a water/(binder:PC + SSA (w/b ratio of 0.5.Se ha estudiado el nivel de corrosion que presentan lasarmaduras embebidas en morteros fabricados con cementoPortland (CP con diferentes porcentajes de sustitucion deceniza de lodo de depuradora (CLD. Se ha utilizado la tecnicade la Resistencia a la Polarizacion para determinar lavelocidad de corrosion del acero embebido en las muestrasestudiadas. Las muestras se han sometido a diferentes condicionesambientales y agentes agresivos: 100% de humedadrelativa (HR, carbonatacion acelerada al 70% HR einmersion en agua de mar. Para la fabricacion de los distintosmorteros, el cemento Portland ha sido parcialmente sustituidopor CLD en los siguientes porcentajes en masa: 0,10, 20, 30 y 60%. Los resultados muestran que sustitucionesde cemento por CLD de hasta el 10% en masa no alteranel comportamiento frente a la corrosion de los morterosal compararlos con los morteros libres de CLD (morteroscontrol: 0% de sustitucion de cemento por CLD. Se

  16. Adición de nanopartículas al cemento portland

    Directory of Open Access Journals (Sweden)

    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

  17. Desarrollo tecnológico de la industria del cemento

    Directory of Open Access Journals (Sweden)

    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.

  18. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  20. La Normalización Nacional e Internacional de cementos

    Directory of Open Access Journals (Sweden)

    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.

  1. 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.

  2. 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

  3. 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.

  4. 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...

  5. Bases tratadas con cemento, en California

    Directory of Open Access Journals (Sweden)

    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.

  6. La industria francesa del cemento su evolución, sus tendencias

    Directory of Open Access Journals (Sweden)

    Coiffu, Pierre

    1961-06-01

    Full Text Available Not availableSeñores: Habiéndome pedido mi querido amigo don Julián Rezola les expusiera a ustedes la evolución de la industria del cemento en la Franela Metropolitana, desde unos años acá, así como sus tendencias actuales, voy a tratar de corresponder de la mejor manera a esta invitación, que tanto me satisface como me honra. Empezaré por situar la industria francesa del cemento, indicando sus características principales, así como los factores que han influido en su evolución, para luego explicarles la manera de cómo los fabricantes han ido resolviendo los problemas que se les han presentado, y examinar sucesivamente la evolución de las diferentes secciones y servicios de una fábrica de cemento. Finalmente, voy a precisarles los resultados de conjunto obtenidos por nuestra industria, y trataré de darles algunas indicaciones sobre sus previsiones futuras.

  7. 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)

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

    Directory of Open Access Journals (Sweden)

    CAROLINA GIRALDO

    2010-01-01

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

  9. 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.

  10. 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.

  11. [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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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].

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

    Directory of Open Access Journals (Sweden)

    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.

  15. 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.

  16. 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.

  17. Evaluation of structural behaviour and corrosion resistant of austenitic AISI 304 and duplex AISI 2304 stainless steel reinforcements embedded in ordinary Portland cement mortars; Evaluacion del comportamiento estructural y de resistencia a la corrosion de armaduras de acero inoxidable austenitico AISI 304 y duplex AISI 2304 embebidas en morteros de cemento Portland

    Energy Technology Data Exchange (ETDEWEB)

    Medina, E.; Cobo, A.; Bastidas, D. M.

    2012-07-01

    The mechanical and structural behaviour of two stainless steels reinforcements, with grades austenitic EN 1.4301 (AISI 304) and duplex EN 1.4362 (AISI 2304) have been studied, and compared with the conventional carbon steel B500SD rebar. The study was conducted at three levels: at rebar level, at section level and at structural element level. The different mechanical properties of stainless steel directly influence the behaviour at section level and structural element level. The study of the corrosion behaviour of the two stainless steels has been performed by electrochemical measurements, monitoring the corrosion potential and the lineal polarization resistance (LPR), of reinforcements embedded in ordinary Portland cement (OPC) mortar specimens contaminated with different amount of chloride over one year time exposure. Both stainless steels specimens embedded in OPC mortar remain in the passive state for all the chloride concentration range studied after one year exposure. (Author) 26 refs.

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

    Directory of Open Access Journals (Sweden)

    Payá, J.

    2008-12-01

    Full Text Available This paper reports on a study of the corrosion levels in steel bars embedded in mortars made with a blend of Portland cement and (0-20% spent fluid catalytic cracking catalyst residue (FC3R, with a variable (0.3-0.7 water/binder (w/b ratio. The specimens were stored in the following conditions: relative humidity of 40, 80 or 100% and CO2 concentrations of 5 and 100%. The steel corrosion rate was measured with polarization resistance techniques. In the absence of aggressive agents, the steel was found to remain duly passivated in mortars with an FC3R content of up to 15% under all the conditions of relative humidity tested. The reinforcement corrosion level in mortars with a w/b ratio of 0.3 and 15% FC3R subjected to accelerated carbonation was similar to the level observed in the unblended Portland cement control mortar.En este trabajo se ha estudiado el nivel de corrosión de barras de acero embebidas en morteros de cemento Portland con relación agua/material cementante (a/mc variable (0,3-0,7, en los que parte del cemento (0-20% se sustituyó por catalizador de craqueo usado (FC3R. Las condiciones de conservación de las probetas elaboradas fueron las siguientes: distintas humedades relativas (40, 80 y 100% y dos concentraciones de CO2 (5 y 100%. La velocidad de corrosión de los aceros se midió mediante la técnica de resistencia de polarización. Se ha podido determinar que, bajo las distintas condiciones de humedad relativa y ausencia de agresivo, los aceros se mantuvieron correctamente pasivados en los morteros con contenidos de FC3R de hasta el 15%. El nivel de corrosión que presenta el refuerzo embebidos en morteros con sustitución de un 15% de cemento por FC3R y relación a/mc 0,3, al ser sometidos a un proceso de carbonatación acelerada, era muy similar al mostrado por el mortero patrón, sin FC3R.

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

    Directory of Open Access Journals (Sweden)

    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.

  20. 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...

  1. Cracks propagation by stress corrosion cracking in conditions of Boiling Water Reactor (BWR); Propagacion de grietas por corrosion bajo esfuerzo en condiciones de reactor de agua hirviente (BWR)

    Energy Technology Data Exchange (ETDEWEB)

    Fuentes C, P

    2003-07-01

    This work presents the results of the assays carried out in the Laboratory of Hot Cells of the National Institute of Nuclear Research (ININ) to a type test tube Compact Tension (CT), built in steel austenitic stainless type 304L, simulating those conditions those that it operates a Boiling Water Reactor (BWR), at temperature 288 C and pressure of 8 MPa, to determine the speed to which the cracks spread in this material that is of the one that different components of a reactor are made, among those that it highlights the reactor core vessel. The application of the Hydrogen Chemistry of the Water is presented (HWC) that is one alternative to diminish the corrosion effect low stress in the component, this is gets controlling the quantity of oxygen and of hydrogen as well as the conductivity of the water. The rehearsal is made following the principles of the Mechanics of Elastic Lineal Fracture (LEFM) that considers a crack of defined size with little plastic deformation in the tip of this; the measurement of crack advance is continued with the technique of potential drop of direct current of alternating signal, this is contained inside the standard Astm E-647 (Method of Test Standard for the Measurement of Speed of Growth of Crack by fatigue) that is the one that indicates us as carrying out this test. The specifications that should complete the test tubes that are rehearsed as for their dimensions, it forms, finish and determination of mechanical properties (tenacity to the fracture mainly) they are contained inside the norm Astm E-399, the one which it is also based on the principles of the fracture mechanics. The obtained results were part of a database to be compared with those of other rehearsals under different conditions, Normal Chemistry of the Water (NWC) and it dilutes with high content of O{sub 2}; to determine the conditions that slow more the phenomena of stress corrosion cracking, as well as the effectiveness of the used chemistry and of the method of

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

    Directory of Open Access Journals (Sweden)

    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.

  3. 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...

  4. 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...

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

    Directory of Open Access Journals (Sweden)

    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.

  6. 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.

  7. 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.

  8. Focal cemento-osseous dysplasia masquerading as a residual cyst

    Directory of Open Access Journals (Sweden)

    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.

  9. [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.

  10. Cemento-ossifying fibroma of the maxilla.

    Science.gov (United States)

    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.

  11. Caracterización de un cemento puzolánico

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  13. La displasia cemento ósea florida y su diagnóstico diferencial

    Directory of Open Access Journals (Sweden)

    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.

  14. 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.

  15. 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.

  16. 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

    Directory of Open Access Journals (Sweden)

    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.

  17. Cenizas, cementos y hormigones con cenizas

    Directory of Open Access Journals (Sweden)

    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.

  18. Costillares. Instituto Técnico de la Construcción y del Cemento

    Directory of Open Access Journals (Sweden)

    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.

  19. 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.

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

    Directory of Open Access Journals (Sweden)

    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

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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

  3. 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.

  4. Los molinos verticales en la industria del cemento

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    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.

  6. 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.

  7. 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...

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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...

  13. 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 ...

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

    Directory of Open Access Journals (Sweden)

    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.

  15. 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.

  16. 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

  17. 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

  18. Normas para la determinación de las resistencias del cemento

    Directory of Open Access Journals (Sweden)

    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.

  19. Empleo racional de los cementos para los diferentes tipos de obras

    Directory of Open Access Journals (Sweden)

    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.

  20. 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.

  1. 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.

  2. Central cemento-ossifying fibroma of posterior maxilla

    Directory of Open Access Journals (Sweden)

    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.

  3. Conservative Management of Central Cemento-Ossifying Fibroma.

    Science.gov (United States)

    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.

  4. 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.

  5. El empleo de carbones en lo industrio del cemento

    Directory of Open Access Journals (Sweden)

    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.

  6. 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.

  7. Cystic Shape Cemento-Ossifying Fibroma of Ethmoid Sinus.

    Science.gov (United States)

    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.

  8. Morphology of the cemento-enamel junction in premolar teeth.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  10. 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.

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

    Directory of Open Access Journals (Sweden)

    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

  12. Estructura y propiedades físicas de la pasta de cemento, fraguado

    Directory of Open Access Journals (Sweden)

    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.

  13. Study of corrosion in metallic coating in steel-carbon by thermal spray; Estudo de corrosao em revestimentos metalicos em aco-carbono obtidos por aspersao termica

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, Maria C.P.; Cavalcanti, Eliane B.; Rambo, Elisabeth S.M.; Araujo, Paulo M.M. [Instituto de Tecnologia e Pesquisa (IPT), Aracaju, SE (Brazil); Santos, Anderson O. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

    2008-07-01

    The effect caused for constituent elements of the watery environment of production of the oil on metallic coverings was studied that simulate the artificial rise of the oil (connecting rods of pump mechanic). For in such a way, the techniques of electrochemical analysis had been used, as the method of linear polarization and the extrapolation of the straight line of Tafel of metallic coverings [alloy of Bronze and Aluminum; alloy of CrNi 80/20; NiCr 80/20; 95MXC (Cr: 26.5% - 31.5%, Cr: 26.5% - 31.5%, B: 3.35% - 4.15%, Mn: 1.1% - 2.2%, Itself: 1.1% -2.1%, Faith) and aluminum] on the substratum steel simulating covering in the connecting rods of pump. Oil well had been raised the resistance characteristics the polarization of the metal when submitted to the watery way surrounding it. They had been evaluated the resistance the covering polarization applied on the steel, with the objective to analyze its resistance the corrosion and to verify the possibility of its use as barrier against the problems originated for the degradation in connecting rods of pump. For the calculated Taxes of Corrosion, it can be concluded that the Aluminum coverings (0,003 mm/year) and NiCr 80/20 (0,179 mm/year) had been the ones that had presented a bigger resistance to the corrosive way. (author)

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

    Directory of Open Access Journals (Sweden)

    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.

  15. Extrusión de cemento sellador endodóntico al espacio periapical

    Directory of Open Access Journals (Sweden)

    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

  16. Estudio de un cemento de las ruinas de Teotihuacan

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    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.

  18. 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.

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

    OpenAIRE

    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...

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

    Directory of Open Access Journals (Sweden)

    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.

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

    OpenAIRE

    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...

  2. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  5. Radio-tracer techniques in the study of corrosion by molten fluorides; Etude, a l'aide d'indicateurs radioactifs, de la corrosion provoquee par les fluorures fondus; Primenenie metodov radioaktivnykh indikatorov nrn izuchenii korrozii, prichinyaemoj rasplavlennymi ftoristymi soedineniyami; Estudio con indicadores radiactivos de la corrosion ocasionada por fluoruros fundidos

    Energy Technology Data Exchange (ETDEWEB)

    Grimes, W R; Watson, G M; DeVan, J H; Evans, R B [Oak Ridge National Laboratory, Oak Ridge, TN (United States)

    1962-03-15

    coefficients de diffusion mesures experimentalement; il est permis d'en conclure que le coefficient d'autodiffusion du chrome est insensible aux modifications de la teneur en chrome de l'alliage Inor-8. (author) [Spanish] Si se someten el Inconel o el Inor-8 a la accion de una mezcla de fluoruros fundidos, que contenga sustancias reducibles, el cromo sufre una oxidacion selectiva y es extraido de la aleacion. Con ayuda del indicador radiactivo {sup 51}Cr, los autores han evaluado los coeficientes de autodifusion del cromo en el Inconel y en el lnor-8, y han comprobado que los datos obtenidos son validos para las aleaciones expuestas a la corrosion. Han calculado los coeficientes globales 1) midiendo el paso del {sup 51}Cr de las capsulas de aleacion (empleado en forma do CrF{sub 2}) a los fluoruros no corrosivos fundidos, y 2) comparando la radiactividad total medida en las muestras de aleacion expuestas con la radiactividad de la sal a cuya accion fueron sometidas. Ademas, calcularon los coeficientes midiendo los perfiles do concentracion del indicador por pulidos electroliticos sucesivos de las muestras. Los coeficientes globales y los obtenidos por pulido electrolitico concuerdan satisfactoriamente para el Inconel a temperaturas elevadas, y para el lnor-8 a todas las temperaturas. Los valores obtenidos por pulido electrolitico del Inconel tratado a temperaturas inferiores a 760{sup o} C superan a los valores globales; en este caso, el proceso de difusion masica no es uniforme. Los coeficientes medios de difusion encontrados concuerdan siempre con los que se calculan por extrapolacion de los valores publicados, que fueron obtenidos con aleaciones de Cr-Ni similares, a temperaturas mas elevadas. Los autores se sirvieron de un par de buees politermicos de Inor-8 para hacer circular una masa de fluoruros no corrosivos fundidos que contenian {sup 51}Cr (en forma de CrF{sub 2}). Sacrificaron uno de estos bucles para evaluar la cantidad de {sup 51}Cr absorbida por la aleacion; el

  6. 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

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

    Directory of Open Access Journals (Sweden)

    Talero Morales, Rafael

    1993-09-01

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

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

    Science.gov (United States)

    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.

  9. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  11. 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...

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  14. Ensayos de resistencia a la compresión de bloques de suelo cemento

    Directory of Open Access Journals (Sweden)

    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.

  15. 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.

  16. 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.

  17. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    OpenAIRE

    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...

  20. 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.

  1. 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.

  2. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

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

    Science.gov (United States)

    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.

  9. Cemento-ossifying fibroma of mandible mimicking complex composite odontome.

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  11. 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....

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

    OpenAIRE

    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.

  13. Florid cemento-osseous dysplasia (FCOD: case report

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  15. Determinación volumétrica de la sílice en el cemento Portland

    Directory of Open Access Journals (Sweden)

    Calleja, J.

    1966-09-01

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

  16. 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

    Directory of Open Access Journals (Sweden)

    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

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  19. 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...

  20. 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.

  1. 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

  2. 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.

  3. 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

    Directory of Open Access Journals (Sweden)

    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.

  4. 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.

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

    Science.gov (United States)

    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.

  6. 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.

  7. 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

  8. 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.

  9. 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…

  10. 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.

  11. 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...

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

    Science.gov (United States)

    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.

  13. 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.

  14. 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

    Directory of Open Access Journals (Sweden)

    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

  15. 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 icorr and Rohm 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 icorr and Rohm 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 icorr y Rohm 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 icorr y Rohm 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.

  16. 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.

  17. 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...

  18. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  20. 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.

  1. Refractarios: un aspecto clave en la industria del cemento

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    Castillo Neira, Percy

    1985-09-01

    Full Text Available To sit in judgement values of the technic level reached in a cement plant, it is surprisingly objetive to analyse work, planning and control development about Refractories subject. Considering and recognizing the validity of this pragmatic axiom it will offer unexpected improvement perspectives of the productivity rates and production records. This work pretends to be a contribution for this purpose, bringing some theoretic and practical accounts about de conditions offered by the Kiln-Exchanger-Cooler most diffused system, analyzing the characteristics that refractory material must have, in accordance with each zone, and finally, including some appraisals and recommendations regarding some of the manifold aspects which belongs to one of the most interesting ad complex fields of cement industry.

    Para establecer un juicio de valor respecto al nivel técnico alcanzado en una planta cementera resulta sorprendentemente objetivo analizar el trabajo, planificación y control que se desarrolla alrededor del tema de Refractarios. Considerarlo y reconocer la validez de este axioma pragmático ofrecerá inusitadas perspectivas de superación de índices de productividad y récords de producción. En este trabajo se pretende un aporte a tal objetivo proporcionando algunas consideraciones teórico-prácticas sobre las condiciones que se presentan en el sistema Horno Intercambiador-Enfriador, más difundido, analizando las características que debe reunir el material refractario para cada zona y, finalmente, incluyendo algunas apreciaciones y recomendaciones principalmente de criterio, respecto a algunos de los múltiples aspectos que forman parte de uno de los campos más interesantes y complejos de la industria del cemento.

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

    OpenAIRE

    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.

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

    Directory of Open Access Journals (Sweden)

    Vázquez, Tomás

    1980-09-01

    Full Text Available Not available

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

  4. 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...

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  7. 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.

  8. 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

  9. 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)

  10. 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 ...

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  14. 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...

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

    Directory of Open Access Journals (Sweden)

    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.

  16. 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.

  17. 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.

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

    Directory of Open Access Journals (Sweden)

    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

  19. 8º Congreso Internacional de la Química de los Cementos Comité Científico Euro-Asiático 1ª Reunión del 14 de Septiembre de 1981 en París

    Directory of Open Access Journals (Sweden)

    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.

  20. Corrosion inhibition

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, A O

    1965-12-29

    An acid corrosion-inhibiting composition consists essentially of a sugar, and an alkali metal salt selected from the group consisting of iodides and bromides. The weight ratio of the sugar to the alkali metal salt is between 2:1 and about 20,000:1. Also, a corrosion- inhibited phosphoric acid composition comprising at least about 20 wt% of phosphoric acid and between about 0.1 wt% and about 10 wt% of molasses, and between about 0.0005 wt% and about 1 wt% of potassium iodide. The weight ratio of molasses to iodide is greater than about 2:1. (11 claims)

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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

  3. Risk evaluation on internal corrosion of a gas pipeline cut section based on metal mechanic tests and physiochemical analysis of the solids deposited in the pipes; Determinacion del riesgo por corrosion interna de un tramo cortado de una linea de transporte de gas natural a partir de ensayos metalmecanicos y del analisis fisicoquimico de los solidos depositados en la tuberia

    Energy Technology Data Exchange (ETDEWEB)

    Ditta Sarmiento, Johanna Milena [PETROBRAS International (BRASPETRO) (Colombia). Ingenieria de Corrosion DPSU

    2003-07-01

    After inspecting a one of the most important pipelines in Colombia, using intelligent tool, the pipe sections were selected that presented losses of thickness which probably they would be risking integrity of the same one and after, these sections were cut and replaced. To one of the cut sections a study with the objective was made him establish the present forms of corrosion and to determine the phenomena that influenced the presence of the damages. For this study were moderate thicknesses of the wall of the tube and was determined the criticality comparing it with its nominal thickness, according to Standard ASME B - 31G. Taking advantage of the presence solids in the surface, one became both, physical and chemical analysis, DRX and elementary analysis, with the objective to determine its origin and to correlate it with the types of corrosion that were in the line. The morphology that determined were Microbiological Influenced Corrosion, Erosion - Corrosion, Pitting and CO2 corrosion. Then, from all this information the analysis becomes of risks by internal corrosion in pipeline, the plan of mitigation and the plans of monitoring and inspection of the line to avoid the presence of anyone of these forms of corrosion in the future immediate. (author)

  4. Corrosion inhibitors

    International Nuclear Information System (INIS)

    El Ashry, El Sayed H.; El Nemr, Ahmed; Esawy, Sami A.; Ragab, Safaa

    2006-01-01

    The corrosion inhibition efficiencies of some triazole, oxadiazole and thiadiazole derivatives for steel in presence of acidic medium have been studied by using AM1, PM3, MINDO/3 and MNDO semi-empirical SCF molecular orbital methods. Geometric structures, total negative charge on the molecule (TNC), highest occupied molecular energy level (E HOMO ), lowest unoccupied molecular energy level (E LUMO ), core-core repulsion (CCR), dipole moment (μ) and linear solvation energy terms, molecular volume (V i ) and dipolar-polarization (π *), were correlated to corrosion inhibition efficiency. Four equations were proposed to calculate corrosion inhibition efficiency. The agreement with the experimental data was found to be satisfactory; the standard deviations between the calculated and experimental results ranged between ±0.03 and ±4.18. The inhibition efficiency was closely related to orbital energies (E HOMO and E LUMO ) and μ. The correlation between quantum parameters and experimental inhibition efficiency has been validated by single point calculations for the semi-empirical AM1 structures using B3LYP/6-31G** as a higher level of theory. The proposed equations were applied to predict the corrosion inhibition efficiency of some related structures to select molecules of possible activity from a presumable library of compounds

  5. 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

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

    Directory of Open Access Journals (Sweden)

    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.

  7. 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

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

    Directory of Open Access Journals (Sweden)

    de la Cruz, Ignacio

    1983-12-01

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

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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  12. 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.

  13. [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.

  14. 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.

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

    Science.gov (United States)

    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.

  16. 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

  17. 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...

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

    Directory of Open Access Journals (Sweden)

    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.

  19. 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.

  20. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    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.

  4. 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.

  5. Investigation of the corrosion resistance of Ti-13Nb-13Zr alloy by electrochemical techniques and surface analysis; Investigacao da resistencia a corrosao da liga Ti-13Nb-13Zr por meio de tecnicas eletroquimicas e de analise de superficie

    Energy Technology Data Exchange (ETDEWEB)

    Assis, Sergio Luiz de

    2006-07-01

    In this work, the in vitro corrosion resistance of the Ti-13Nb-13Zr alloy, manufactured at a national laboratory, and used for orthopedic applications, has been investigated in solutions that simulate the body fluids. The electrolytes used were 0.9 % (mass) NaCl, Hanks' solution, a culture medium (MEM), and the two last electrolytes, without and with addition of hydrogen peroxide. The aim of peroxide addition was to simulate the conditions found when inflammatory reactions occur due to surgical procedures. The corrosion resistance of alloys commercially in use as biomaterials, Ti-6Al-7Nb and Ti-6Al-4V, as well as of the pure titanium (Ti-cp), was also studied for comparison with the Ti-13Nb-13Zr alloy. The corrosion resistance characterization was carried out by electrochemical and surface analysis techniques. The electrochemical tests used were: open circuit potential measurements as a function of tim; potentiodynamic polarization; and electrochemical impedance spectroscopy (EIE). The impedance experimental diagrams were interpreted using equivalent electric circuits that simulate an oxide film with a duplex structure composed of an internal and compact, barrier type layer, and an external porous layer. The results showed that the corrosion resistance is due mainly to the barrier type layer. The titanium alloys and the Ti-cp showed high corrosion resistance in all electrolytes used. The oxides formed on the Ti-13Nb-13Zr, either naturally or during immersion in MEM ar Hank's solution was characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (MEV). The results showed that the presence of hydrogen peroxide in MEM promotes the growth of the porous layer and incorporation of mineral ions, besides favouring hydroxyapatite formation. The cytotoxicity of the Ti-13Nb-13Zr alloy was also evaluated and it was shown to be non-toxic. (author)

  6. Investigation of the corrosion resistance of Ti-13Nb-13Zr alloy by electrochemical techniques and surface analysis; Investigacao da resistencia a corrosao da liga Ti-13Nb-13Zr por meio de tecnicas eletroquimicas e de analise de superficie

    Energy Technology Data Exchange (ETDEWEB)

    Assis, Sergio Luiz de

    2006-07-01

    In this work, the in vitro corrosion resistance of the Ti-13Nb-13Zr alloy, manufactured at a national laboratory, and used for orthopedic applications, has been investigated in solutions that simulate the body fluids. The electrolytes used were 0.9 % (mass) NaCl, Hanks' solution, a culture medium (MEM), and the two last electrolytes, without and with addition of hydrogen peroxide. The aim of peroxide addition was to simulate the conditions found when inflammatory reactions occur due to surgical procedures. The corrosion resistance of alloys commercially in use as biomaterials, Ti-6Al-7Nb and Ti-6Al-4V, as well as of the pure titanium (Ti-cp), was also studied for comparison with the Ti-13Nb-13Zr alloy. The corrosion resistance characterization was carried out by electrochemical and surface analysis techniques. The electrochemical tests used were: open circuit potential measurements as a function of tim; potentiodynamic polarization; and electrochemical impedance spectroscopy (EIE). The impedance experimental diagrams were interpreted using equivalent electric circuits that simulate an oxide film with a duplex structure composed of an internal and compact, barrier type layer, and an external porous layer. The results showed that the corrosion resistance is due mainly to the barrier type layer. The titanium alloys and the Ti-cp showed high corrosion resistance in all electrolytes used. The oxides formed on the Ti-13Nb-13Zr, either naturally or during immersion in MEM ar Hank's solution was characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (MEV). The results showed that the presence of hydrogen peroxide in MEM promotes the growth of the porous layer and incorporation of mineral ions, besides favouring hydroxyapatite formation. The cytotoxicity of the Ti-13Nb-13Zr alloy was also evaluated and it was shown to be non-toxic. (author)

  7. Aircraft Corrosion

    Science.gov (United States)

    1981-08-01

    attribud au choix de traitements et de rev~tements spproprids. Au contrairo, dens d’sutros structures des corrosions iirportsntea se sont msnifestdes...au traitement . micaniqus qui provoque une compression de surface - h1l’spplication i1’une double protection comportant oxydation snodique et...chlore mais dans une proportion semblable b cells d’une eau de vil)e ; - lea solides, d’aprbs lea analyses chimique et criatallographique, paraissaiont

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

    Directory of Open Access Journals (Sweden)

    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

  9. 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...

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

    Directory of Open Access Journals (Sweden)

    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.

  11. El cemento y el concreto de los mayas

    Directory of Open Access Journals (Sweden)

    Horacio Ramírez de Alba

    1999-01-01

    Full Text Available Se realiza un estudio técnico sobre los materiales utilizados por los constructores mayas, quienes lograron obras cuyos vestigios maravillan hoy al mundo. Se presentan los resultados obtenidos al realizar pruebas físicas y químicas en muestras de estucos, morteros y concretos provenientes de zonas arqueológicas, principalmente Palenque y Yaxchilán, en el estado de Chiapas, México.

  12. El cemento y el concreto de los mayas

    OpenAIRE

    Horacio Ramírez de Alba; Ramiro Pérez Campos; Heriberto Díaz Coutiño

    1999-01-01

    Se realiza un estudio técnico sobre los materiales utilizados por los constructores mayas, quienes lograron obras cuyos vestigios maravillan hoy al mundo. Se presentan los resultados obtenidos al realizar pruebas físicas y químicas en muestras de estucos, morteros y concretos provenientes de zonas arqueológicas, principalmente Palenque y Yaxchilán, en el estado de Chiapas, México.

  13. 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.)

  14. 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

  15. Characterization and corrosion behavior of phytic acid coatings, obtained by chemical conversion on magnesium substrates in physiological solution; Caracterizacion y comportamiento frente a la corrosion de recubrimientos de acido fitico, obtenidos por conversion quimica, sobre substratos de magnesio en solucion fisiologica

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Alvarado, L. A.; Lomeli, M. A.; Hernandez, L. S.; Miranda, J. M.; Narvaez, L.; Diaz, I.; Garcia-Alonso, M. C.; Escudero, M. L.

    2014-10-01

    In order to improve the corrosion resistance of biodegradable magnesium and AZ31 magnesium alloy implants, a phytic acid coating has been applied on both substrates and their protective effect against corrosion has been assessed. The morphology and the chemical nature of the conversion coating were analyzed by SEM/EDX, XRD and FTIR. The spectra showed that the conversion coating was amorphous, and it was composed of Mg, O, and P on magnesium surface, along with Al, Zn and C on AZ31 alloy. The main coating components were chelate compounds formed by phytic acid and metallic ions. The corrosion resistance of bare and coated samples was evaluated by potentiodynamic polarization technique in Hank's solution at 37 degree centigrade. The results indicate that phytic acid conversion coatings provided a very effective protection to the magnesium substrates studied. (Author)

  16. Evaluation of the susceptibility to corrosion by pites of supermartensitic stainless steel with different superficial finishing; Avaliacao da susceptibilidade a corrosao por pites do aco inoxidavel supermartensitico com diferentes acabamentos superficiais

    Energy Technology Data Exchange (ETDEWEB)

    Freitas, Mario Jose Bueno de Souza

    2015-07-01

    The objective of this study is to evaluate the susceptibility by pitting corrosion in a supermartensitic stainless steel (13%Cr) with different surface finishes, in an environment that simulates the conditions found in the range of the Brazilian marine subsoil before the dense layer of salt - the so-called pre-salt. In this study were conducted electrochemical tests of potentiodynamic anodic polarization and electrochemical impedance spectroscopy (EIS) in environment containing 35, 50 and 190 g/L of NaCl and dissolved oxygen concentrations <10, 100 and 500ppb. Were also used the techniques of Moessbauer spectroscopy and EDS (Energy Dispersive Spectrometry) coupled to a scanning electron microscope (SEM) for microstructural characterization of 13%Cr steel. It was observed by the electrochemical tests, the increase in the concentration of chloride ions in solution makes the studied steel more susceptible to localized corrosion. It was also observed that the material showed less susceptibility to pitting corrosion when its surface was less rough. (author)

  17. 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

    Directory of Open Access Journals (Sweden)

    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

  18. Cementos odontológicos a base de Poli (ácido acrílico y wollastonita

    Directory of Open Access Journals (Sweden)

    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.

  19. 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.

  20. Introducción a la fabricación y normalización del cemento portland

    OpenAIRE

    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...

  1. Valorización de Cementos Pacasmayo S.A.A.

    OpenAIRE

    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, ...

  2. Plan estratégico para Cemento Pacasmayo S.A.

    OpenAIRE

    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 ...

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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...

  9. Perfil logístico del sector del cemento en Colombia

    OpenAIRE

    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 ...

  10. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  12. 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

  13. 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...

  14. 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)

    OpenAIRE

    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...

  15. 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

  16. Evaluation and mitigation of the degradation by corrosion in the components of the service water system of a nuclear power plant; Evaluacion y mitigacion de la degradacion por corrosion en los componentes del sistema de agua de servicio de una planta nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Salaices A, E.; Salaices, M.; Ovando, R. [IIE, Av. Reforma 113 Col. Palmira, 62490 Cuernavaca, Morelos (Mexico)]. e-mail: sal@iie.org.mx

    2005-07-01

    One of the main problems that face the nuclear power stations is the degradation by corrosion in the service water systems. The corrosion causes lost substantial in energy generation and a high cost in maintenance and repairs. In this work, the results of a study of the degradation by the MIC mechanisms (microorganisms influenced corrosion), incrustations in heat exchangers and erosion for solid particles in the components of a typical service water system of a nuclear plant are presented. Diverse mitigation options are analyzed for these mechanisms. In the analysis, it was used the CHECWORKS-CWA code to carry out the evaluation of the degradation so much as well as the mitigation of the caused damage. The results are presented in susceptibility indexes and degradation rates component-by-component. A significant decrement could be observed in the susceptibility to MIC when changing the operation conditions of stagnated flow to continuous flow. With respect to the erosion by solid particles, it was found a significant reduction of the damage it when adding filters to the system. Finally, in the case of the heat exchangers, it is shown that one of the more viable options to diminish incrustations and existent calcium deposits it is the reduction of the pH of the service water. (Author)

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

    OpenAIRE

    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...

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

    Directory of Open Access Journals (Sweden)

    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.

  19. Estudo das características de revestimentos poliméricos aplicados por aspersão térmica para proteção contra desgaste e corrosão de substratos metálicos Study of the characteristics of thermally sprayed polymer coatings for wear and corrosion protection of metallic substrates

    Directory of Open Access Journals (Sweden)

    Carlos Roberto Camello Lima

    2012-12-01

    Full Text Available Revestimentos poliméricos vêm sendo crescentemente considerados como solução na proteção de materiais metálicos contra corrosão e desgaste. A tecnologia de aspersão térmica permite a aplicação de polímeros sobre diversos materiais de substrato, em diversas espessuras, para várias condições ambientais. Polímeros depositados por este processo têm potencial, tanto para reduzir custos com materiais, como para melhorar o desempenho do revestimento em ambientes agressivos. Neste trabalho, foram aplicados revestimentos poliméricos poli-éter-éter-cetona (PEEK e Poliamida 12 sobre substratos de aço carbono, utilizando o processo de aspersão térmica a chama de baixa velocidade. Revestimentos de alta qualidade foram obtidos por esta técnica. Foram avaliadas as características dos materiais e dos revestimentos obtidos, especialmente quanto às propriedades mecânicas, de desgaste e corrosão. De acordo com os resultados obtidos, pode-se afirmar que os revestimentos estudados podem ser utilizados com sucesso em aplicações que envolvam desgaste e corrosão, com uma pequena vantagem para o polímero PEEK.Polymer coatings have been widely considered as a solution in the protection of metallic substrates against both wear and corrosion. Thermal spray technology allows the deposition of polymers onto several substrate materials for various thicknesses at several environmental conditions. Thermal sprayed polymers have high potential for material cost reduction as well as to improve coating performance in drastic environments. In this work, poly-ether-ether-ketone (PEEK and Polyamide 12 were flame sprayed on carbon steel substrates. High quality coatings were obtained. Several tests were carried out to evaluate the coatings mainly related to wear and corrosion performance. According to the obtained results, it can be stated that the studied coatings can be successfully used in applications involving wear and corrosion, with a slight edge

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

    Science.gov (United States)

    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.

  1. 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

    Directory of Open Access Journals (Sweden)

    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

  2. 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

  3. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  6. Rehabilitation of the gas pipeline that had a rupture in service caused by SCC (Stress Corrosion C raking); Rehabilitacion al servicio de un gasoducto que ha sufrido una ruptura en servicio por SCC

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Fernando; Carzoglio, Eduardo; Hryciuk, Pedro [TGN - Transportadora de Gas del Norte S.A. (Argentina). Depto. de Integridad

    2003-07-01

    TGN had a rupture in service on Gasoducto Troncal Norte. After initial evaluation of the causes of the rupture it was concluded that it had been caused by Stress Corrosion Cracking (SCC). Subsequent investigation in the area of the rupture revealed that colonies of cracks, typical of SCC were found in pipes located near the rupture. In order to put back in service the pipeline in a safety condition, SCC mitigation activities were performed. A decision was made to conduct a hydro test along approximately 30 kilometers of pipe. The stages of the works, the problems faced and the solutions found are dealt with, as well as the conclusions reached upon completion of the works which allowed a better understanding of SCC phenomenon. The methodology for the identification of those areas susceptible to SCC is also described. (author)

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

    Directory of Open Access Journals (Sweden)

    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.

  8. 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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  10. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  12. Modelación con elementos finitos del agrietamiento en el hormigón por corrosión localizada en la armadura Finite element modeling of cracking in concrete due to localized corrosion in the reinforcement

    Directory of Open Access Journals (Sweden)

    J Castorena

    2007-04-01

    Full Text Available En base a estudios con elemento finito, en el presente trabajo se obtiene un modelo capaz de predecir la cantidad de acero corroído (rcrit en la armadura necesaria para que aparezca la primera grieta visible en la superficie del recubrimiento del hormigón. Para el análisis con elemento finito se utiliza el software ANSYS, el cual dispone del elemento SOLID65, con el que es posible modelar el hormigón simple, ya que tiene la capacidad de sufrir aplastamiento en compresión y agrietarse a tracción. El caso de la capa de óxido es modelado mediante elementos de contacto CONTA174, y la armadura con SOLID65, pero sin las opciones de aplastamiento y agrietamiento. El modelo obtenido está en función del recubrimiento libre, diámetro del refuerzo, tipo de hormigón y la longitud corroída, denominada ésta longitud anódica. Los resultados muestran la gran influencia que tiene la corrosión localizada (longitud anódica pequeña-longitud catódica grande sobre el cálculo de rcrit, y que dicho efecto sólo es posible analizarlo de manera tridimensional. Así mismo, se muestra la eficiencia de utilizar los elementos de contacto CONTA174 para representar el crecimiento de óxidos. El modelo obtenido explica en un 92% el fenómeno y se compara con resultados experimentales encontrados en la literaturaBased on studies with finite element method, a model able to predict the quantity of steel corrosion (rcrit necessary for the first visible crack appearance in the surface of the concrete cover was obtained. For the finite element analysis the software ANSYS was used, which has the element SOLID65, with which is possible to model plain concrete, since has the capacity to show crushing in compression and to cracking in tension. The case of the oxide layer is modeled by means of contact elements CONTA174 and the steel with SOLID65, but without the crushing and cracking options. The obtained model is in function of the free cover, diameter of the

  13. 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

    Directory of Open Access Journals (Sweden)

    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

  14. 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 ...

  15. 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...

  16. 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....

  17. Evaluation of the susceptibility to pitting corrosion of steel api 5L x42 exposed to solutions containing chloride ions and CO{sub 2} by electrochemical noise measurements; Evaluacion de la susceptibilidad a la corrosion por picado del acero api 5l x42 expuesto a un ambiente con cloruros y CO{sub 2} mediante la tecnica de ruido electroquimico

    Energy Technology Data Exchange (ETDEWEB)

    Pena-Ballesteros, D.; Rodriguez-Vanegas, N.; Anteliz, C.; Sarmiento Klapper, H.

    2011-07-01

    The concentration of chloride ions and the partial pressure of CO{sub 2} play an important role in the degradation of low-carbon steels used for the construction of pipelines in oil and gas industry. In order to evaluate the susceptibility of carbon steel API 5L X42 to pitting corrosion electrochemical noise and linear polarization resistance measurements were carried out in aqueous solutions containing chloride ions and CO{sub 2}. The concentration of chloride ions was varied between, 10000 and 18000 ppm, and the CO{sub 2} partial pressure between 10 psi and 18 psi. Experimental results pointed out that the formation of protective layer, consisting mainly of FeCO{sub 3}, depends on the partial pressure of CO{sub 2} in the system. Nevertheless, the stability of this layer was considerably affected by increasing the concentration of chloride ions causing that localized corrosion has taken place in some areas of the surface of API 5L X42, which were detected by electrochemical noise technique. (Author) 10 refs.

  18. Comparative study in the induced corrosion by sulfate reducing microorganisms, in a stainless steel 304L sensitized and a carbon steel API X65; Estudio comparativo de la corrosion inducida por microorganismos sulfatorreductores, en un acero inoxidable 304L sensibilizado y un acero al carbono API X65

    Energy Technology Data Exchange (ETDEWEB)

    Diaz S, A.; Gonzalez F, E.; Arganis J, C.; Luna C, P.; Carapia M, L. [ININ, Carretera Mexico-Toluca Km. 36.5, 52045 Estado de Mexico (Mexico)]. e-mail: ads@nuclear.inin.mx

    2004-07-01

    In spite of the operational experience related with the presence of the phenomenon of microbiological corrosion (MIC) in industrial components, it was not but until the decade of the 80 s when the nuclear industry recognized its influence in some systems of Nuclear Generating Power plants. At the moment, diverse studies that have tried to explain the generation mechanism of this phenomenon exist; however, they are even important queries that to solve, especially those related with the particularities of the affected metallic substrates. Presently work, the electrochemical behavior of samples of stainless steel AISI 304L sensitized is evaluated and the carbon steel APIX65, before the action of sulfate reducing microorganisms low the same experimental conditions; found that for the APIX65 the presence of this type of bacteria promoted the formation of a stable biofilm that allowed the maintenance of the microorganisms that damaged the material in isolated places where stings were generated; while in the AISI 304L, it was not detected damage associated to the inoculated media. The techniques of Resistance to the Polarization and Tafel Extrapolation, allowed the calculation of the speed of uniform corrosion, parameter that doesn't seem to be influenced by the presence of the microorganisms; while that noise electrochemical it distinguished in real time, the effect of the sulfate reducing in the steel APIX65. (Author)

  19. 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

  20. Microbiological corrosion of metals

    International Nuclear Information System (INIS)

    Vladislavlev, V.V.

    1992-01-01

    Problems is considered of development of the microbiological corrosion of the NPP equipment. The main attention is paid to the selective character of microbiological corrosion in zones of welded joints of austenitic steels. It is noted that the presence of technological defects promotes growth of corrosional damages. Methods for microbiological corrosion protection are discussed

  1. 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....

  2. 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

  3. 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.

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

    Science.gov (United States)

    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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

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

    Science.gov (United States)

    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.

  10. COMPORTAMIENTO DE UN CEMENTO ASFÁLTICO MODIFICADO CON UN DESECHO DE PVC

    Directory of Open Access Journals (Sweden)

    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.

  11. 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.

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

    Directory of Open Access Journals (Sweden)

    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

  13. 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

    Directory of Open Access Journals (Sweden)

    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.

  14. 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.

  15. 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.

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

    Directory of Open Access Journals (Sweden)

    Janneth Torres Agredo

    2012-06-01

    Full Text Available In this article the possibility of using waste from the petrochemical industry,as partial replacement of Portland cement is studied, evaluating the presenceof contaminants in the waste and the encapsulation, once it is confined on the cement. This has been done, in order to find a use to this residue without cause damage to the environment. This residue, called spent fluid catalytic cracking catalyst (FCC, is mainly formed by a type Y zeolite, which is dispersing in an inorganic oxides matrix. The toxicity characteristic leaching proceeding was applied, in mortars adding with 20% of FCC as Portland cement replacement. The results showed that the residue does not represent a problem from the point of view of the leaching of elements, such as As, Pb, Zn, Cr, and La, which were below to the permissible limits. Additionally, the pozzolanic activity of FCC was evaluated according to ASTM C311, where the efficiency of the residue as pozzolanic addition is demonstrated. With the results the importance of reusing a residue of the petrochemical industry is emphasized, that decreases the amount of cement to be used and improves the mechanical resistance of the materials containing it.En el presente artículo se estudia la posibilidad de utilizar un residuo de la industria petroquímica, como sustitución parcial del cemento Portland, evaluando la presencia de elementos contaminantes en el residuo y su encapsulación, una vez se haya confinado con el cemento. Lo anterior, con el fin de determinar si su uso como material de construcción, puede o no causar un efecto negativo al medio ambiente. El residuo, denominado catalizador usado de craqueo catalítico (FCC, es un material que está compuesto por una zeolita tipo Y, dispersa en una matriz de óxidos inorgánicos. Se aplicó la técnica de TCLP (del inglés Toxicity Characteristic Leaching Procedure, en morteros adicionados con un 20%, de FCC con respecto a la cantidad de cemento. Los resultados

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

    Science.gov (United States)

    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.

  18. 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)

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

    Directory of Open Access Journals (Sweden)

    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.

  20. 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.

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

    OpenAIRE

    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...

  2. Hot corrosion of the steel SA213-T22 and SA213-TP347H in 80% V{sub 2}O{sub 5}-20%Na{sub 2}SO{sub 4} mixture; Corrosion por depositos salinos de los aceros SA213-T22 y SA213-TP347H en presencia de una mezcal 80%V{sub 2} O{sub 5}-20%Na{sub 2}SO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Almeraya, F; Martinez-Villafane, A; Gaona, C; Romero, M A; Malo, J M

    1998-06-01

    Many hot corrosion problems in industrial and utility boilers are caused by molten salts. The corrosion processes which occur in salts are of an electrochemical nature, and so they can be studied using electrochemical test methods. In this research, electrochemical techniques in molten salt systems have been used for the measurements of molten corrosion processes. Electrochemical test methods are described here for a salt mixture of 80%V{sub 2}O{sub 5}-20%NaSO{sub 4} at 540-680 degree centigree. To establish better the electrochemical corrosion rate measurements for molten salt systems, information from electrochemical potentiodynamic polarization curves, such as polarization resistance and Tafeol slopes were used in this study to generate corrosion rate data. The salt was contained in a quartz crucible inside a stainless retort. The atmosphere used was air. A thermocouple sheathed with quartz glass was introduced into the molten salt for temperature monitoring and control. Two materials were tested in the molten mixture: SA213-T22 and SA213-TP347H steels. The corrosion rates values obtained using electrochemical methods were around 0.58-7.14 mm/yr (22.9-281 mpy). The corrosion rate increase with time. (Author) 7 refs.

  3. Dominância coronariana em corações humanos em moldes por corrosão Coronary dominance patterns in the human heart investigated by corrosion casting

    Directory of Open Access Journals (Sweden)

    Décio Cavalet Soares Abuchaim

    2009-12-01

    Full Text Available OBJETIVO: Esse trabalho tem como objetivo analisar os padrões de dominância circulatória de corações humanos, o número de ramos que a artéria coronária direita fornece ao ventrículo esquerdo, o número de ramos que a artéria coronária esquerda fornece ao direito e a presença de anastomoses intercoronarianas, com sua localização e frequência. MÉTODOS: Foram produzidos 25 moldes de corações submetidos à instilação de acrílico colorido e posterior corrosão com ácido clorídrico, no Laboratório de Cirurgia Experimental da FURB. Peças com lesões e cicatrizes não foram usadas. RESULTADOS: Os corações pertenciam a indivíduos de ambos os sexos, sendo 17 (68% de indivíduos do sexo masculino, com idade média de 40,2 anos (15 a 70 anos. A dominância direita ocorreu em 18 (72% peças, com 1, 2, 3 e 4 ramos em 2, 14, 2 e 1 moldes, respectivamente; a dominância esquerda foi observada em 5 (20% casos, com 1 ramo em 4 moldes e 2 em 1 molde; e a dominância balanceada foi verificada em 2 (8% moldes. Houve diferença significativa entre a dominância direita e esquerda (α > 5%, direita e balanceada (α > 5% e sem significância entre esquerda e balanceada (α OBJECTIVES: The aim of this work was to analyze the dominance patterns of the circulation of the human heart, the number of branches from the right coronary artery to the left ventricle, the number of branches from the left coronary artery to the right ventricle and the frequency and location of intercoronary anastomoses. METHODS: Casts were made of 25 hearts by the injection of colored acrylic resin and subsequent corrosion using hydrochloric acid at the experimental surgery laboratory of Furb. Specimens with lesions or scars were discarded. RESULTS: The hearts, from both men (17 - 68% and women (8 - 32%, had a mean age of 40.2 (15 to 70 years-old. Right dominance occurred in 18 (72% subjects, with 1, 2, 3 and 4 branches leading to the left ventricle in 2, 14, 2 and 2

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

    Directory of Open Access Journals (Sweden)

    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.

  5. 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.

  6. 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...

  7. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  9. 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

  10. Coatings and Corrosion Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — Purpose: The mission of the Coatings and Corrosion Laboratory is to develop and analyze the effectiveness of innovative coatings test procedures while evaluating the...

  11. 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.

  12. 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

    Directory of Open Access Journals (Sweden)

    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

  13. 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

  14. 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

  15. Aluminum Corrosion and Turbidity

    International Nuclear Information System (INIS)

    Longtin, F.B.

    2003-01-01

    Aluminum corrosion and turbidity formation in reactors correlate with fuel sheath temperature. To further substantiate this correlation, discharged fuel elements from R-3, P-2 and K-2 cycles were examined for extent of corrosion and evidence of breaking off of the oxide film. This report discusses this study

  16. Demystifying Controlling Copper Corrosion

    Science.gov (United States)

    The LCR systematically misses the highest health and corrosion risk sites for copper. Additionally, there are growing concerns for WWTP copper in sludges and discharge levels. There are many corrosion control differences between copper and lead. This talk explains the sometimes c...

  17. Archaeological analogs and corrosion

    International Nuclear Information System (INIS)

    David, D.

    2008-01-01

    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.)

  18. 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

    Directory of Open Access Journals (Sweden)

    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.

  19. 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)

  20. 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

  1. Corrosion fatigue of steels

    International Nuclear Information System (INIS)

    Spaehn, H.; Wagner, G.H.

    1976-01-01

    Corrosion fatigue phenomena can be classified into two main groups according to the electrochemical state of the metal surface in the presence of electrolytes: the active and the passive state with an important sub-group of corrosion fatigue in the unstable passive state. The allowable stress for structures exposed to the conjoint action of corrosion and fatigue is influenced by many factors: kind of media, number of cycles, frequency, mean stress, size, notches, loading mode, alloy composition and mechanical strength. A critical literature review shows contradictory results if a classification by the electrochemical surface state is not applied. Case histories and counter measures illustrate the practical importance of corrosion fatigue in many branches of industry as well as the urgent need for a better knowledge about the mutual influence of the phenomena to get rules by which the engineer can appraise the risk of corrosion fatigue. (orig.) [de

  2. Observaciones acerca de la dosificación de cemento en morteros y hormigones fraguados

    Directory of Open Access Journals (Sweden)

    Calleja Carrete, J.

    1965-09-01

    Full Text Available Present methods to determine the proportioning of cements in conglomerates, and specifically cement (whether Portland or not in set mortars and concretes, have general limitations which in most practical cases have the disadvantage that they involve considerable errors. In given cases, which are usually unexpected, these errors may considerably increase, and render useless the inferences that could be drawn therefrom. To avoid this it is necessary to supplement these methods with other means of determining the cement content. This will be especially so if the results could lead to serious economic consequences, or to evaluate responsibilities of any other type.Los métodos al uso para determinar la dosificación de conglomerantes en conglomerados, y más concretamente de cemento (portland o no en morteros y hormigones fraguados, tienen, en general, limitaciones que les hacen adolecer en la mayoría de los casos prácticos de errores considerables. En circunstancias determinadas, generalmente imprevistas, estos errores pueden aumentar notablemente e invalidar los resultados y las conclusiones que de los mismos pudieran extraerse. En evitación de ello es preciso entonces complementar los métodos con otras determinaciones, particularmente si el dictamen basado en el resultado hallado para la dosificación puede afectar seriamente a intereses económicos, o determinar una responsabilidad de cualquier tipo.

  3. 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.

  4. Imaging the Cemento-Enamel Junction Using a 20-MHz Ultrasonic Transducer.

    Science.gov (United States)

    Nguyen, Kim-Cuong T; Le, Lawrence H; Kaipatur, Neelambar R; Major, Paul W

    2016-01-01

    The cemento-enamel junction (CEJ), which is the intersection between enamel and cementum, is an important landmark in the diagnosis of periodontal disease. Pulse-echo ultrasound was used to image the CEJs of six porcine lower central incisors with a single 20-MHz transducer. A notch was longitudinally created on the enamel as a stable marker, from which the CEJ was measured. Data were acquired along the tooth's axis at 0.4-mm intervals. Time-distance data were bandpass-filtered to enhance signal-to-noise ratio and record density was increased fourfold to 0.1-mm spacing by a frequency-distance interpolation scheme. Reflections from the CEJ were unambiguously identified along with those from enamel, dentin and cementum. The notch-CEJ distances measured by the ultrasound and micro-computed tomography methods correlated strongly (r = 0.996, p < 0.05) and were in good agreement with the 95% lines of agreement between -0.49 and 0.17 mm, as statistically determined by Bland-Altman analysis. The results indicate the potential of ultrasound to be a reliable and non-ionizing technique to image the CEJ. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  5. The location of cemento enamel junction for CAL measurement: A clinical crisis

    Directory of Open Access Journals (Sweden)

    Vandana K

    2009-01-01

    Full Text Available Background: We face various problems while measuring the Clinical attachment level (CAL from Cemento-enamel junction (CEJ. This study aims to record and compare the CEJ location measurements using a xed reference point (FRP [Custom made stent] before and after ap elevation. Materials and Methods: A custom made stent and UNC-15 probe were used. Recording of CEJ location was made using a UNC-15 (Hu-Friedy probe, before (close CEJ and after (Open CEJ the reflection of the flap from the lower edge of the stent in those subjects who were indicated for flap surgery, at baseline. Results: We used statistical analysis involving intra-group comparison done by Paired-′t′ test. The close and the open CEJ measurements demonstrated a, statistically, non-significant difference. The equi-measurements of close and open CEJ numerical data were remarkably lower than the under and overestimation of measurements. Thus, despite certain disadvantages of stent, the FRP provides a simple solution for CAL measurement. Conclusion: The results of this study confirms the objective of the study and strongly suggests that CAL measurements done without FRP is subjected to great variation and the diagnostic and prognostic interpretation of CAL should be viewed seriously in periodontics.

  6. Clinical and radiographic features of solitary and cemento-osseous dysplasia-associated simple bone cysts.

    Science.gov (United States)

    Chadwick, J W; Alsufyani, N A; Lam, E W N

    2011-05-01

    The simple bone cyst (SBC) is a pseudocyst that can occur as a solitary entity in the jaws or may occur in association with cemento-osseous dysplasia (COD). The purpose of this study was to review the clinical and radiographic features of solitary and COD-associated SBCs. Archived imaging reports from the Special Procedures Clinic in Oral and Maxillofacial Radiology at the Faculty of Dentistry at the University of Toronto between 1 January 1989 and 31 December 2009 revealed 23 COD-associated SBCs and 68 solitary SBCs. Almost all solitary and COD-associated SBCs were found in the mandible. Furthermore, 87.0% of COD-associated SBCs were found in females in their fifth decade of life (P < 0.001) while solitary SBCs were found in equal numbers in both sexes in their second decade of life (P < 0.005). COD-associated SBCs were also more likely to cause thinning of the endosteal cortex, bone expansion and scalloping of the superior border between teeth (all P < 0.001) than solitary SBCs that are classically described as having these characteristics. Finally, COD-associated SBC demonstrated a loss of lamina dura more often (P < 0.05) than solitary SBCs. Knowledge of the sporadic association between COD and SBC and their potential radiographic appearances should prevent inappropriate treatment and management of these patients.

  7. Accuracy of probing attachment levels using a new computerized cemento-enamel junction probe.

    Science.gov (United States)

    Deepa, R; Prakash, Shobha

    2012-01-01

    The assessment of clinical attachment level (CAL) represents the gold standard for diagnosing and monitoring periodontal disease. The aim of the present study was to evaluate the performance of the newly introduced cemento-enamel junction (CEJ) probe in detecting CAL, using CEJ as a fixed reference point, and to compare the CEJ probe with the Florida stent probe (FSP) as well as with a standard manual probe, University of North Carolina-15 (UNC-15). Three examiners recorded the probing attachment level in 384 sites in case group (chronic periodontitis), and in 176 sites, in control group (healthy periodontal status), using the three probes. Subjects included both the sexes and ranged from 35 to 45 years. The experimental design was structured to balance the intra- and inter-examiner consistency at the same site during the two visits. CEJ probe showed higher intra-and inter-examiner consistency over both FSP and UNC-15 in both the case and control groups. Frequency distribution of differences of various magnitudes of repeated measurements ≤1 mm was in the higher range of 86.8% to 87.5% for CEJ probe. The FSP was more reproducible than UNC-15 in detecting relative attachment level (RAL). CEJ automated probe was found to have greatest potential for accuracy and consistency in detecting CAL than FSP and UNC-15. The automated probes appeared to be more reproducible than manual probes.

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

    Directory of Open Access Journals (Sweden)

    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.

  9. 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.

  10. 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.

  11. The Wnt/β-catenin pathway is deregulated in cemento-ossifying fibromas.

    Science.gov (United States)

    Pereira, Thaís Dos Santos Fontes; Diniz, Marina Gonçalves; França, Josiane Alves; Moreira, Rennan Garcias; Menezes, Grazielle Helena Ferreira de; Sousa, Sílvia Ferreira de; Castro, Wagner Henriques de; Gomes, Carolina Cavaliéri; Gomez, Ricardo Santiago

    2018-02-01

    The molecular pathogenesis of cemento ossifying fibroma (COF) is unclear. The purpose of this study was to investigate mutations in 50 oncogenes and tumor suppressor genes, including APC and CTNNB1, in which mutations in COF have been previously reported. In addition, we assessed the transcriptional levels of the Wnt/β-catenin pathway genes in COF. We used a quantitative polymerase chain reaction array to evaluate the transcriptional levels of 44 Wnt/β-catenin pathway genes in 6 COF samples, in comparison with 6 samples of healthy jaws. By using next-generation sequencing (NGS) in 7 COF samples, we investigated approximately 2800 mutations in 50 genes. The expression assay revealed 12 differentially expressed Wnt/β-catenin pathway genes in COF, including the upregulation of CTNNB1, TCF7, NKD1, and WNT5 A, and downregulation of CTNNBIP1, FRZB, FZD6, RHOU, SFRP4, WNT10 A, WNT3 A, and WNT4, suggesting activation of the Wnt/β-catenin signaling pathway. NGS revealed 5 single nucleotide variants: TP53 (rs1042522), PIK3 CA (rs2230461), MET (rs33917957), KIT (rs3822214), and APC (rs33974176), but none of them was pathogenic. Although NGS detected no oncogenic mutation, deregulation of key Wnt/β-catenin signaling pathway genes appears to be relevant to the molecular pathogenesis of COF. Copyright © 2017 Elsevier Inc. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    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.

  13. 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

    Directory of Open Access Journals (Sweden)

    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

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

    Directory of Open Access Journals (Sweden)

    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.

  15. Automated Methods Of Corrosion Measurements

    DEFF Research Database (Denmark)

    Bech-Nielsen, Gregers; Andersen, Jens Enevold Thaulov; Reeve, John Ch

    1997-01-01

    The chapter describes the following automated measurements: Corrosion Measurements by Titration, Imaging Corrosion by Scanning Probe Microscopy, Critical Pitting Temperature and Application of the Electrochemical Hydrogen Permeation Cell.......The chapter describes the following automated measurements: Corrosion Measurements by Titration, Imaging Corrosion by Scanning Probe Microscopy, Critical Pitting Temperature and Application of the Electrochemical Hydrogen Permeation Cell....

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

    OpenAIRE

    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...

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

    Directory of Open Access Journals (Sweden)

    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.

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

    OpenAIRE

    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 ...

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

    OpenAIRE

    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...

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

    Directory of Open Access Journals (Sweden)

    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.

  1. Corrosion in power industry

    International Nuclear Information System (INIS)

    Ventakeshwarlu, K.S.

    1979-01-01

    A brief account of the problem areas encountered as a result of corrosion in the electrical power industry including nuclear power industry is given and some of the measures contemplated and/or implemented to control corrosion are outlined. The corrosion problems in the steam generators and cladding tubes of the nuclear power plant have an added dimension of radioactivation which leads to contamination and radiation field. Importance of monitoring water quality and controlling water chemistry by addition of chemicals is emphasised. (M.G.B.)

  2. Corrosion of reactor materials

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1963-01-15

    Much operational experience and many experimental results have accumulated in recent years regarding corrosion of reactor materials, particularly since the 1958 Geneva Conference on the Peaceful Uses of Atomic Energy, where these problems were also discussed. It was, felt that a survey and critical appraisal of the results obtained during this period had become necessary and, in response to this need, IAEA organized a Conference on the Corrosion of Reactor Materials at Salzburg, Austria (4-9 June 1962). It covered many of the theoretical, experimental and engineering problems relating to the corrosion phenomena which occur in nuclear reactors as well as in the adjacent circuits

  3. 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....

  4. 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)

  5. 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...

  6. 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...

  7. Corrosion of valve metals

    International Nuclear Information System (INIS)

    Draley, J.E.

    1976-01-01

    A general survey related to the corrosion of valve metals or film-forming metals. The way these metals corrode with some general examples is described. Valve metals form relatively perfect oxide films with little breakdown or leakage when anodized

  8. Corrosion in Electronics

    DEFF Research Database (Denmark)

    Ambat, Rajan; Gudla, Helene Virginie Conseil; Verdingovas, Vadimas

    2017-01-01

    Electronic control units, power modules, and consumer electronics are used today in a wide variety of varying climatic conditions. Varying external climatic conditions of temperature and humidity can cause an uncontrolled local climate inside the device enclosure. Uncontrolled humidity together...... and high density packing combined with the use of several materials, which can undergo electrochemical corrosion in the presence of water film formed due to humidity exposure and bias conditions on the PCBA surface. This article provides a short review of the corrosion reliability issues of electronics due...... to the use of electronics under varying humidity conditions. Important PCBA aspects, which are fundamental to the corrosion cell formation under humid conditions, are discussed. Effect of hygroscopic residues from the process and service and their role in assisting water film build up and corrosion...

  9. Microbiologically Influenced Corrosion

    Science.gov (United States)

    2009-01-01

    species grow as multicel- lular filaments called hyphae forming a mycelium, some fungal species also grow as single cells. Sexual and asexual...reinforced fluorinated 18 MICROBIOLOGICALLY INFLUENCED CORROSION polyimide composites due to hyphae penetration into resin interiors. The

  10. Carbon Dioxide Corrosion:

    DEFF Research Database (Denmark)

    Fosbøl, Philip Loldrup

    2008-01-01

    CO2 corrosion is a general problem in the industry and it is expensive. The focus of this study is an oil gas production related problem. CO2 corrosion is observed in offshore natural gas transportation pipelines. A general overview of the problem is presented in chapter 1. The chemical system...... with the basic thermodynamics of electrolytes in chapter 2, the extension and general description of electrolyte mass transport in chapter 3, and the electrochemical kinetics of corrosion in chapter 4. A literature overview of CO2 corrosion is shown in chapter 5 and possible extensions of the models...... and validated against heat capacity data. The model is also fitted to experimental data produced and shown in chapter 8 for SLE in the Na2CO3-NaHCO3-MEG-H2O system. The application of the above model is shown in chapter 9. Here the thermodynamic correction factors are calculated. These show how the diffusion...

  11. BWR steel containment corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Tan, C.P.; Bagchi, G.

    1996-04-01

    The report describes regulatory actions taken after corrosion was discovered in the drywell at the Oyster Creek Plant and in the torus at the Nine Mile Point 1 Plant. The report describes the causes of corrosion, requirements for monitoring corrosion, and measures to mitigate the corrosive environment for the two plants. The report describes the issuances of generic letters and information notices either to collect information to determine whether the problem is generic or to alert the licensees of similar plants about the existence of such a problem. Implementation of measures to enhance the containment performance under severe accident conditions is discussed. A study by Brookhaven National Laboratory (BNL) of the performance of a degraded containment under severe accident conditions is summarized. The details of the BNL study are in the appendix to the report.

  12. Corrosion Inhibitors for Aluminum.

    Science.gov (United States)

    Muller, Bodo

    1995-01-01

    Describes a simple and reliable test method used to investigate the corrosion-inhibiting effects of various chelating agents on aluminum pigments in aqueous alkaline media. The experiments that are presented require no complicated or expensive electronic equipment. (DDR)

  13. Cemento-Osseous Dysplasias: Imaging Features Based on Cone Beam Computed Tomography Scans.

    Science.gov (United States)

    Cavalcanti, Paulo Henrique Pereira; Nascimento, Eduarda Helena Leandro; Pontual, Maria Luiza Dos Anjos; Pontual, Andréa Dos Anjos; Marcelos, Priscylla Gonçalves Correia Leite de; Perez, Danyel Elias da Cruz; Ramos-Perez, Flávia Maria de Moraes

    2018-01-01

    Imaging exams have important role in diagnosis of cemento-osseous dysplasia (COD). Cone beam computed tomography (CBCT) stands out for allowing three-dimensional image evaluation. This study aimed to assess the prevalence of cases diagnosed as COD on CBCT scans, as well identify the main imaging features related to these lesions. An analysis was performed in a database containing 22,400 radiological reports, in which all cases showing some type of COD were initially selected. These CBCT exams were reevaluated to confirm the radiographic diagnosis and determine the prevalence and distribution of the types of COD with regard to gender, age and preferred location, while describing its most common imaging aspects. Data were presented using descriptive analyses. There were 82 cases diagnosed as COD in the CBCT images (prevalence of 0.4%). The distribution of patients was 11 (13.4%) male and 71 (86.6%) female, with a mean age of 49.8 years (age-range 17-85 years). There were 47 (57.3%) cases of periapical COD, 23 (28%) of focal COD and 12 (14.6%) of florid COD. The mandible was more affected than the maxilla. In most cases, the lesions were mixed or hyperdense. All COD had well-defined limits and there were no cases of tooth displacement. In conclusion, periapical COD was the most common type and the most affected bone was the mandible. Imaging evaluation is critical for diagnosis and dentists should bear in mind all possible radiographic presentations of COD in order to prevent misleading diagnoses and consequently, inadequate treatments.

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

    Directory of Open Access Journals (Sweden)

    Lima, José I.

    1994-02-01

    Full Text Available The article seeks to show the influence of humidity on the compression test of the soil-cement bricks through an adapted experimental design. The equations showing this relation are obtained. The subsequent generalization provides the possibility of making a pattern of correlation of strengths with different test humidities. Thus, the tests could be performed with a given humidity and the strength of the particular specimen for different humidity values could be estimated with a high degree of certainty. This makes possible the comparison of strength between tested elements in different humidity conditions, verification of fulfillment of recommended strength values and their expressing in terms of a basic humidity value, which is what the currently valid Technical Instructions lack.

    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 nivel de confianza. Esto posibilita que se puedan realizar comparaciones de resistencia entre elementos ensayados en condiciones desiguales de humedad, verificar el cumplimiento de los valores recomendados de resistencia y referirlos a un valor de humedad base, defecto actual de las Instrucciones Técnicas vigentes.

  15. Criterios de intervención en forjados con viguetas de cemento aluminoso

    Directory of Open Access Journals (Sweden)

    Casanovas, Xavier

    1992-12-01

    Full Text Available This article deals with the problems concerning structural security of 900,000 houses wiht high alumina cement in Spain between 1950 and 1970. Three groups of solutions are suggested in order to make this difficult mission possible - carry out the intervention in such a large estate with the occupants inside. l.-Accept the present performance with the help of a reliable analysis, applying the prevention measures, service control and limited use; 2.-Repair and reinforcements improving the bearing capacity or decreasing the acting loads; 3.-Replacing the members in poor physical or functional conditions; there are various proposals for application of different techniques and materials (whose production is already industrialized which would optimize and facilitate such interventions.

    El artículo recoge la problemática referida a la seguridad estructural de 900.000 viviendas construidas con cemento aluminoso en el Estado Español, entre 1950 y 1970. Se plantean las dificultades que representa el actuar en un parque tan extenso y con sus ocupantes en el interior, proponiéndose tres grupos de soluciones: 1.-Aceptar el comportamiento actual en base a una diagnosis fiable y con aplicación de medidas de prevención, seguimiento en servicio y limitaciones de uso; 2.-Reparaciones y refuerzos, mejorando la capacidad portante o reduciendo las solicitaciones; 3.-Substitución de los elementos en mal estado, física o funcionalmente, presentándose diversas propuestas actualmente industrializadas que optimizan y facilitan los trabajos de este tipo, aplicando diferentes técnicas y materiales.

  16. 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

  17. 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...

  18. 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.)

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    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.

  1. 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.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

  4. Hydrogen peroxide using in control of H{sub 2} S and C N{sup -} corrosion in aqueous medium; Emprego de peroxido de hidrogenio no controle da corrosao por H{sub 2} S e CN{sup -} em meio aquoso

    Energy Technology Data Exchange (ETDEWEB)

    Correa, Luiz Augusto; Ferreira, Luiz Antonio [PETROBRAS/REPAR, Araucaria, PR (Brazil). Refinaria Presidente Getulio Vargas; Baptista, Walmar [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas

    1998-07-01

    This paper presents the system for corrosion control in the equipment for gas separation in the catalytic cracking, developed by PETROBRAS, Brazil. The system uses hydrogen peroxide as a CN{sup -} neutralization agent.

  5. 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

    Directory of Open Access Journals (Sweden)

    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

  6. 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

  7. 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

  8. 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

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

    Directory of Open Access Journals (Sweden)

    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.

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

    OpenAIRE

    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...

  11. 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.)

  12. Resistencia química del hormigón XXII. 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 de mar artificial

    Directory of Open Access Journals (Sweden)

    Sagrera-Moreno, José Luis

    1984-03-01

    D 1141-75 en donde han estado sumergidas las series de probetas de mortero (1: 3 hechas con un cemento portland industrial de alta resistencia inicial (cemento 1 < > P-550-ARI y con las mezclas cemento 1/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 el contenido de los iones Ca (II, Mg (II y SO4 (II de las nuevas fases sólidas formadas en dichos medios de conservación-ataque. La composición estructural de dichas fases sólidas y de la fracción enriquecida de las mencionadas probetas de mortero se determinó por DRX, de ello se dio cuenta en (3. En los casos estudiados se ha puesto de manifiesto que se produce un incremento de Ca (II en la disolución y en las nuevas fases sólidas, así como del valor del pH, que dependen de la mezcla utilizada para fabricar las diversas series de probetas de mortero y del tiempo de conservación-ataque. Dichas cantidades de Ca (II experimentan, para cada edad, una fuerte disminución conforme la cantidad de cemento 1 de la mezcla es menor y un incremento, para cada mezcla, conforme aumenta el tiempo de conservación-ataque; este incremento es suave para el caso de los medios en donde han estado sumergidas las probetas hechas con las mezclas que tienen los mayores contenidos de escoria (60 y 70%, en peso. Si, además, se tiene en cuenta el contenido de Ca (II en el agua de mar artificial ASTM el proceso de disolución de Ca (II es aditivo. El contenido de Mg (II del agua de mar artificial ASTM (4,43 X 10-2 moles/800 ml experimenta en todos los casos estudiados una disminución que es función de la mezcla utilizada en la fabricación de las diversas series de probetas de mortero y del tiempo de conservación-ataque, que influyen en las condiciones del medio y, de un modo especial, en la concentraci

  13. Algunas cuestiones jurídicas en torno al uso del cemento aluminoso

    Directory of Open Access Journals (Sweden)

    Olaya Adán, Manuel

    1992-12-01

    Full Text Available The legal issues raised by the use of a particular product or construction material have their references in complex administrative guidelines which take into account the corresponding technical control. Such guidelines develop with the time as the technical and scientific knowledge shapes new ideas. In the case of defects in construction which can be attributed to the use of the material in question, the legal effects reach the field of civil or, where appropriate, penal responsibility. This article analyzes different questions related to the case of the use of high alumina cement. Thefocus is limited to explaining the State of the art during the period in which the material was used to manufacture precast construction elements. The article brings a current view of the legal effects on the civil field through three reference regulations.

    La problemática jurídica que suscita el uso de un determinado producto o material de construcción tiene sus referencias en una normativa compleja de naturaleza administrativa contemplada en la correspondiente regulación técnica. Tal normativa evoluciona en el tiempo a medida que los conocimientos técnicos y científicos determinan nuevas prescripciones. En el caso de fallos en construcción achacables al uso del material en cuestión, los efectos jurídicos transcienden a ámbitos de responsabilidad civil o, en su caso, penal. En el presente artículo se analizan diversas cuestiones relacionadas con el caso del uso del cemento aluminoso. El enfoque se circunscribe a exponer el estado del arte durante el período en que el material fue empleado en la confección de elementos constructivos prefabricados y se aporta una visión actual de los efectos jurídicos en el ámbito civil a través de tres normas de referencia en la materia.

  14. Acid corrosion inhibitor

    Energy Technology Data Exchange (ETDEWEB)

    Chen, N G

    1964-04-28

    An acid corrosion inhibitor is prepared by a 2-stage vacuum evaporation of effluents obtained from the ammonia columns of the coking oven plant. The effluent, leaving a scrubber in which the phenols are removed at a temperature of 98$C, passes through a quartz filter and flows into a heated chamber in which it is used for preheating a solution circulating through a vacuum unit, maintaining the temperature of the solution at 55$ to 60$C. The effluent enters a large tank in which it is boiled at 55$ to 60$C under 635 to 640 mm Hg pressure. Double evaporation of this solution yields a very effective acid corrosion inhibitor. Its corrosion-preventing effect is 97.9% compared with 90.1% for thiourea and 88.5% for urotropin under identical conditions.

  15. Plastics for corrosion inhibition

    CERN Document Server

    Goldade, Victor A; Makarevich, Anna V; Kestelman, Vladimir N

    2005-01-01

    The development of polymer composites containing inhibitors of metal corrosion is an important endeavour in modern materials science and technology. Corrosion inhibitors can be located in a polymer matrix in the solid, liquid or gaseous phase. This book details the thermodynamic principles for selecting these components, their compatibility and their effectiveness. The various mechanisms of metal protection – barrier, inhibiting and electromechanical – are considered, as are the conflicting requirements placed on the structure of the combined material. Two main classes of inhibited materials (structural and films/coatings) are described in detail. Examples are given of structural plastics used in friction units subjected to mechano-chemical wear and of polymer films/coatings for protecting metal objects against corrosion.

  16. Corrosion Monitoring System

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Russ Braunling

    2004-10-31

    The Corrosion Monitoring System (CMS) program developed and demonstrated a continuously on-line system that provides real-time corrosion information. The program focused on detecting pitting corrosion in its early stages. A new invention called the Intelligent Ultrasonic Probe (IUP) was patented on the program. The IUP uses ultrasonic guided waves to detect small defects and a Synthetic Aperture Focusing Technique (SAFT) algorithm to provide an image of the pits. Testing of the CMS demonstrated the capability to detect pits with dimensionality in the sub-millimeter range. The CMS was tested in both the laboratory and in a pulp and paper industrial plant. The system is capable of monitoring the plant from a remote location using the internet.

  17. Stochastic theory of fatigue corrosion

    Science.gov (United States)

    Hu, Haiyun

    1999-10-01

    A stochastic theory of corrosion has been constructed. The stochastic equations are described giving the transportation corrosion rate and fluctuation corrosion coefficient. In addition the pit diameter distribution function, the average pit diameter and the most probable pit diameter including other related empirical formula have been derived. In order to clarify the effect of stress range on the initiation and growth behaviour of pitting corrosion, round smooth specimen were tested under cyclic loading in 3.5% NaCl solution.

  18. 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.

  19. 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...

  20. 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...

  1. 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

    Directory of Open Access Journals (Sweden)

    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.

  2. 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

    Directory of Open Access Journals (Sweden)

    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

  3. Rhenium corrosion in chloride melts

    International Nuclear Information System (INIS)

    Stepanov, A.D.; Shkol'nikov, S.N.; Vetyukov, M.M.

    1989-01-01

    The results investigating rhenium corrosion in chloride melts containing sodium, potassium and chromium ions by a gravimetry potentials in argon atmosphere in a sealing quarth cell are described. Rhenium corrosion is shown to be rather considerable in melts containing CrCl 2 . The value of corrosion rate depending on temperature is determined

  4. Accelerated cyclic corrosion tests

    Directory of Open Access Journals (Sweden)

    Prošek T.

    2016-06-01

    Full Text Available Accelerated corrosion testing is indispensable for material selection, quality control and both initial and residual life time prediction for bare and painted metallic, polymeric, adhesive and other materials in atmospheric exposure conditions. The best known Neutral Salt Spray (NSS test provides unrealistic conditions and poor correlation to exposures in atmosphere. Modern cyclic accelerated corrosion tests include intermittent salt spray, wet and dry phases and eventually other technical phases. They are able to predict the material performance in service more correctly as documented on several examples. The use of NSS should thus be restricted for quality control.

  5. 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

  6. Development of tubings 3 percent of CR with higher CO{sub 2} corrosion resistance for exploration and production of oil and gas; Desenvolvimento de 'tubings' 3 % cromo com maior resistencia a corrosao por CO{sub 2} para exploracao e producao de petroleo e gas

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Ricardo Nolasco de; Loureiro, Flavio Guerra; Ferreira, Marcelo Almeida Cunha [V e M do Brasil, Belo Horizonte, MG (Brazil); Coelho, Sonia Maria [Instituto Nacional de Tecnologia (INT), Rio de Janeiro, RJ (Brazil). Div. de Quimica; Baptista, Ilson Palmieri [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas

    2008-07-01

    On of the most important issues of petroleum and gas industries is the corrosion of equipment for exploitation and production, due to its implications in the depreciation and operational costs, besides environmental, health and safety concerns. The CO{sub 2} corrosion is one of the main causes of failures in oil wells and one of available technological alternatives to its control is the increase in the steel chromium content. This work presents the development of tubings with chromium contents close to 3 %, for application in CO{sub 2} containing wells. The chemical analysis was designed in order to maximize chromium in solid solution meeting, at the same time, the mechanical properties of a API L 80. The evaluation of corrosion resistance was done through static and dynamic tests with p CO{sub 2} of 1b ar, pH of 4,0 and 5,0 and temperatures of 25, 50 and 70 deg C. In general, the steel with 3 % of chromium showed uniform corrosion approximately 3 times lower, besides crevice corrosion, pitting and polarization resistance were superior than that form reference steel, API L 80 type 1. The good results coming from laboratory incentives even more the run field tests, which started recently in Campos Basin PETROBRAS wells. (author)

  7. Corrosion resistant cemented carbide

    International Nuclear Information System (INIS)

    Hong, J.

    1990-01-01

    This paper describes a corrosion resistant cemented carbide composite. It comprises: a granular tungsten carbide phase, a semi-continuous solid solution carbide phase extending closely adjacent at least a portion of the grains of tungsten carbide for enhancing corrosion resistance, and a substantially continuous metal binder phase. The cemented carbide composite consisting essentially of an effective amount of an anti-corrosion additive, from about 4 to about 16 percent by weight metal binder phase, and with the remaining portion being from about 84 to about 96 percent by weight metal carbide wherein the metal carbide consists essentially of from about 4 to about 30 percent by weight of a transition metal carbide or mixtures thereof selected from Group IVB and of the Periodic Table of Elements and from about 70 to about 96 percent tungsten carbide. The metal binder phase consists essentially of nickel and from about 10 to about 25 percent by weight chromium, the effective amount of an anti-corrosion additive being selected from the group consisting essentially of copper, silver, tine and combinations thereof

  8. Corrosion resistant steel

    International Nuclear Information System (INIS)

    Zubchenko, A.S.; Borisov, V.P.; Latyshev, V.B.

    1980-01-01

    Corrosion resistant steel for production of sheets and tubes containing C, Mn, Cr, Si, Fe is suggested. It is alloyed with vanadium and cerium for improving tensile properties and ductility. The steel can be melted by a conventional method in electric-arc or induction furnaces. The mentioned steel is intended to be used as a substitute for nickel-bearing austenitic steels

  9. Corrosion in seawater systems

    International Nuclear Information System (INIS)

    Henrikson, S.

    1988-01-01

    Highly alloyed stainless steels have been exposed to natural chlorinated and chlorine-free seawater at 35 deg. C. Simulated tube-tubesheet joints, weld joints and galvanic couples with titanium, 90/10 CuNi and NiAl bronze were tested and evaluated for corrosion. The corrosion rates of various anode materials - zinc, aluminium and soft iron - were also determined. Finally the risk of hydrogen embrittlement of tubes of ferritic stainless steels and titanium as a consequence of cathodic protection was studied. An attempt was also made to explain the cracking mechanism of the ferritic steels by means of transmission electron microscopy. One important conclusion of the project is that chlorinated seawater is considerably more corrosive to stainless steels than chlorine-free water, whereas chlorination reduces the rate of galvanic corrosion of copper materials coupled to stainless steels. Hydrogen embrittlement of ferritic stainless steels and titanium as a consequence of cathodic protection of carbon steel or cast iron in the same structure can be avoided by strict potentiostatic control of the applied potential. (author)

  10. Corrosion resistant composite materials

    International Nuclear Information System (INIS)

    Ul'yanin, E.A.

    1986-01-01

    Foundations for corrosion-resistant composite materials design are considered with account of components compatibility. Fibrous and lamellar composites with metal matrix, dispersion-hardened steels and alloys, refractory metal carbides-, borides-, nitrides-, silicides-based composites are described. Cermet compositions and fields of their application, such as protective coatings for operation in agressive media at high temperatures, are presented

  11. Development of Nb{sub 2}O{sub 5}|Cu composite as AISI 1020 steel thermal spray coating for protection against corrosion by soil in buried structures; Desenvolvimento e uso do composito de Nb{sub 2}O{sub 5}|Cu como revestimento aplicado por aspersao termica sobre o aco AISI 1020 para protecao contra a corrosao pelo solo em estruturas enterradas

    Energy Technology Data Exchange (ETDEWEB)

    Regis Junior, Oscar [Universidade Tecnologica Federal do Parana, Ponta Grossa, PR (Brazil). Dept. de Mecanica; Silva, Jose Maurilio da; Portella, Kleber Franke [Instituto de Tecnologia para o Desenvolvimento, Curitiba, PR (Brazil). Dept. de Pesquisa em Engenharia Civil; Paredes, Ramon Sigifredo Cortes, E-mail: regis@utfpr.edu.br [Universidade Federal do Parana, Curitiba, PR (Brazil). Dept. de Mecanica

    2012-07-01

    An Nb{sub 2}O|Cu corrosion-resistant coating was developed and applied onto AISI 1020 steel substrate by Powder Flame Spray. A galvanostatic electrochemical technique was employed, with and without ohmic drop, in four different soils (two corrosively aggressive and two less aggressive). Behavior of coatings in different soils was compared using a cathodic hydrogen reduction reaction (equilibrium potential, overvoltage and exchange current density) focusing on the effect of ohmic drop. Results allow recommendation of Nb{sub 2}O{sub 5}|Cu composite for use in buried structure protection. (author)

  12. Smart Coatings for Corrosion Protection

    Science.gov (United States)

    Calle, Luz Marina; Li, Wendy; Buhrow, Jerry W.; Johnsey, Marissa N.

    2016-01-01

    Nearly all metals and their alloys are subject to corrosion that causes them to lose their structural integrity or other critical functionality. It is essential to detect corrosion when it occurs, and preferably at its early stage, so that action can be taken to avoid structural damage or loss of function. Protective coatings are the most commonly used method of corrosion control. However, progressively stricter environmental regulations have resulted in the ban of many commercially available corrosion protective coatings due to the harmful effects of their solvents or corrosion inhibitors. This work concerns the development of a multifunctional, smart coating for the autonomous control of corrosion. This coating is being developed to have the inherent ability to detect the chemical changes associated with the onset of corrosion and respond autonomously to indicate it and control it.

  13. Corrosion potential analysis system

    Science.gov (United States)

    Kiefer, Karl F.

    1998-03-01

    Many cities in the northeastern U.S. transport electrical power from place to place via underground cables, which utilize voltages from 68 kv to 348 kv. These cables are placed in seamless steel pipe to protect the conductors. These buried pipe-type-cables (PTCs) are carefully designed and constantly pressurized with transformer oil to prevent any possible contamination. A protective coating placed on the outside diameter of the pipe during manufacture protects the steel pipe from the soil environment. Notwithstanding the protection mechanisms available, the pipes remain vulnerable to electrochemical corrosion processes. If undetected, corrosion can cause the pipes to leak transformer oil into the environment. These leaks can assume serious proportions due to the constant pressure on the inside of the pipe. A need exists for a detection system that can dynamically monitor the corrosive potential on the length of the pipe and dynamically adjust cathodic protection to counter local and global changes in the cathodic environment surrounding the pipes. The northeastern United States contains approximately 1000 miles of this pipe. This milage is critical to the transportation and distribution of power. So critical, that each of the pipe runs has a redundant double running parallel to it. Invocon, Inc. proposed and tested a technically unique and cost effective solution to detect critical corrosion potential and to communicate that information to a central data collection and analysis location. Invocon's solution utilizes the steel of the casing pipe as a communication medium. Each data gathering station on the pipe can act as a relay for information gathered elsewhere on the pipe. These stations must have 'smart' network configuration algorithms that constantly test various communication paths and determine the best and most power efficient route through which information should flow. Each network station also performs data acquisition and analysis tasks that ultimately

  14. The effect of corrosion on stained glass windows

    Directory of Open Access Journals (Sweden)

    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

  15. Hormigón con bajo contenido de cemento y hormigón con sustitución parcial de cemento

    Directory of Open Access Journals (Sweden)

    Calleja, José

    1982-12-01

    Full Text Available Some time ago an Inquiry concerning the items exposed in the title of this Report was prepared and circulated by the Norwegian member of the CEB/Commission VIII, among the members of this Commission. The responses received so far have been collected and studied, and the ordered content of them has been exposed in this Report according to the items involved in the Inquiry. Short general conclusions have been drawn from the mentioned content.

    Hace algún tiempo se preparó y difundió por el miembro noruego (12 del CEB (Comité Europeo de Hormigón, entre los componentes de la Comisión VIII del mismo (Tecnología y Control de Calidad de Hormigón, una Encuesta sobre los títulos que encabezan este trabajo. Las respuestas recibidas fueron estudiadas por el firmante del mismo, a petición de dicha Comisión VIII del CEB, y el contenido ordenado de dichas respuestas constituye el objeto de este Informe, en el cual se hacen destacar algunas conclusiones de aquélla. Entre las respuestas mencionadas figuraba la española, la cual corrió, en su momento, a cargo del autor del presente trabajo.

  16. 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

  17. 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.

  18. 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.

  19. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  1. 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

  2. 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)

  3. 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.

  4. Scanning reference electrode techniques in localized corrosion

    International Nuclear Information System (INIS)

    Isaacs, H.S.; Vyas, B.

    1979-04-01

    The principles, advantages, and implementations of scanning reference electrode techniques are reviewed. Data related to pitting, intergranular corrosion, welds and stress corrosion cracking are presented. The technique locates the position of localized corrosion and can be used to monitor the development of corrosion and changes in the corrosion rate under a wide range of conditions

  5. Corrosion control for low-cost reliability

    International Nuclear Information System (INIS)

    Anon.

    1993-01-01

    This conference was held September 19-24, 1993 in Houston, Texas to provide a forum for exchange of state-of-the-art information on corrosion. Topics of interest focus on the following: atmospheric corrosion; chemical process industry corrosion; high temperature corrosion; and corrosion of plant materials. Individual papers have been processed separately for inclusion in the appropriate data bases

  6. CHECWORKS integrated software for corrosion control

    International Nuclear Information System (INIS)

    Schefski, C.; Pietralik; Hazelton, T.

    1997-01-01

    CHECWORKS, a comprehensive software package for managing Flow-Accelerated Corrosion (FAC, also called erosion-corrosion and flow-assisted corrosion) concerns, is expanding to include other systems and other aspects of corrosion control in CANDU reactors. This paper will outline CHECWORKS applications at various CANDU stations and further plans for CHECWORKS to become a code for comprehensive corrosion control management. (author)

  7. 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

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

    Directory of Open Access Journals (Sweden)

    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.

  9. Anti-Corrosion Coating

    Science.gov (United States)

    1986-01-01

    SuperSpan RM 8000 is an anti-corrosion coating which effectively counteracts acid degradation, abrasive wear, and cracking in power industry facilities. It was developed by RM Industrial Products Company, Inc. with NERAC assistance. It had previously been necessary to shut down plants to repair or replace corroded duct-work in coal burning utilities. NASA-developed technology was especially useful in areas relating to thermoconductivity of carbon steel and the bonding characteristics of polymers. The product has sold well.

  10. Corrosion in power engineering

    International Nuclear Information System (INIS)

    1988-03-01

    The proceedings contain the full texts of 25 papers of which 10 fall under the INIS Subject Scope. They concern the problems of corrosion in WWER type nuclear power plants. The topics include structural materials and equipment of the primary and the secondary circuits of nuclear power plants, components used in disposal of spent nuclear fuel, sodium valves for fast reactors and basic study of the properties of materials used in nuclear power. (Z.M.). 12 figs., 6 tabs., 46 refs

  11. Air corrosion in storing

    International Nuclear Information System (INIS)

    Mazaudier, F.; Feron, D.; Baklouti, M.; Midoux, N.

    2001-01-01

    The air corrosiveness of a radioactive waste package has been estimated in a store inside which the environmental conditions are supposed to be rather close to the outside ones. It is expressed according to the ISO 9223 standard, from the humidification value and the amounts of sulfur dioxide and chlorine ions. A computer code has been perfected too; the thermal behaviour of the package can then been determined. (O.M.)

  12. Corrosion Protection of Aluminum

    Science.gov (United States)

    Dalrymple, R. S.; Nelson, W. B.

    1963-07-01

    Treatment of aluminum-base metal surfaces in an autoclave with an aqueous chromic acid solution of 0.5 to 3% by weight and of pH below 2 for 20 to 50 hrs at 160 to 180 deg C produces an extremely corrosion-resistant aluminum oxidechromium film on the surface. A chromic acid concentration of 1 to 2% and a pH of about 1 are preferred.

  13. 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

    Directory of Open Access Journals (Sweden)

    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

  14. Corrosion of beryllium oxide

    International Nuclear Information System (INIS)

    Elston, J.; Caillat, R.

    1958-01-01

    Data are reported on the volatilization rate of beryllium oxide in moist air depending on temperature and water vapour concentration. They are concerned with powder samples or sintered shapes of various densities. For sintered samples, the volatilization rate is very low under the following conditions: - temperature: 1300 deg. C, - water vapour concentration in moist air: 25 g/m 3 , - flow rate: 12 I/hour corresponding to a speed of 40 m/hour on the surface of the sample. For calcinated powders (1300 deg. C), grain growth has been observed under a stream of moist air at 1100 deg. C. For instance, grain size changes from 0,5 to at least 2 microns after 500 hours of exposure at this temperature. Furthermore, results data are reported on corrosion of sintered beryllium oxide in pressurized water. At 250 deg. C, under a pressure of 40 kg/cm 2 water is very slightly corrosive; however, internal strains are revealed. Finally, some features on the corrosion in liquid sodium are exposed. (author) [fr

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

    Directory of Open Access Journals (Sweden)

    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.

  16. Zircaloy-4 corrosion in PWR's

    International Nuclear Information System (INIS)

    Fyfitch, S.; Smalley, W.R.; Roberts, E.

    1985-01-01

    Zircaloy-4 waterside corrosion has been studied extensively in the nuclear industry for a number of years. Following the early crud-related corrosion failures in the Saxton test reactor, Westinghouse undertook numerous programs to minimize crud deposition on fuel rods in power reactors through primary coolant chemistry control. Modern plants today are operating with improved coolant chemistry guidelines, and crud deposition levels are very low in proportion to earlier experience. Zircaloy-4 corrosion under a variety of coolant chemistry, heat flux and exposure conditions has been studied extensively. Experience to date, even in relatively high coolant temperature plants, has indicated that -for both fuel cladding and structural components- Zircaloy-4 waterside corrosion performance has been excellent. Recognizing future industry trends, however, which will result in Zircaloy-4 being subjected to ever increasing corrosion duties, Westinghouse will continue accumulating Zircaloy-4 corrosion experience in large power plants. 13 refs.

  17. Nuclear corrosion science and engineering

    CERN Document Server

    2012-01-01

    Understanding corrosion mechanisms, the systems and materials they affect, and the methods necessary for accurately measuring their incidence is of critical importance to the nuclear industry for the safe, economic and competitive running of its plants. This book reviews the fundamentals of nuclear corrosion. Corrosion of nuclear materials, i.e. the interaction between these materials and their environments, is a major issue for plant safety as well as for operation and economic competitiveness. Understanding these corrosion mechanisms, the systems and materials they affect, and the methods to accurately measure their incidence is of critical importance to the nuclear industry. Combining assessment techniques and analytical models into this understanding allows operators to predict the service life of corrosion-affected nuclear plant materials, and to apply the most appropriate maintenance and mitigation options to ensure safe long term operation. This book critically reviews the fundamental corrosion mechani...

  18. Pipe Lines – External Corrosion

    Directory of Open Access Journals (Sweden)

    Dan Babor

    2008-01-01

    Full Text Available Two areas of corrosion occur in pipe lines: corrosion from the medium carried inside the pipes; corrosion attack upon the outside of the pipes (underground corrosion. Electrolytic processes are also involved in underground corrosion. Here the moisture content of the soil acts as an electrolyte, and the ions required to conduct the current are supplied by water-soluble salts (chlorides, sulfates, etc. present in the soil. The nature and amount of these soluble materials can vary within a wide range, which is seen from the varying electrical conductivity and pH (varies between 3 and 10. Therefore the characteristics of a soil will be an important factor in under-ground corrosion.

  19. Accelerated Stress-Corrosion Testing

    Science.gov (United States)

    1986-01-01

    Test procedures for accelerated stress-corrosion testing of high-strength aluminum alloys faster and provide more quantitative information than traditional pass/fail tests. Method uses data from tests on specimen sets exposed to corrosive environment at several levels of applied static tensile stress for selected exposure times then subsequently tensile tested to failure. Method potentially applicable to other degrading phenomena (such as fatigue, corrosion fatigue, fretting, wear, and creep) that promote development and growth of cracklike flaws within material.

  20. Corrosion of fuel assembly materials

    International Nuclear Information System (INIS)

    Noe, M.; Frejaville, G.; Beslu, P.

    1985-08-01

    Corrosion of zircaloy-4 is reviewed in relation with previsions of improvement in PWRs performance: higher fuel burnup; increase coolant temperature, implying nucleate boiling on the hot clad surfaces; increase duration of the cycle due to load-follow operation. Actual knowledge on corrosion rates, based partly on laboratory tests, is insufficient to insure that external clad corrosion will not constitute a limitation to these improvements. Therefore, additional testing within representative conditions is felt necessary [fr

  1. Corrosion Monitors for Embedded Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Alex L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pfeifer, Kent B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Casias, Adrian L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Howell, Stephen W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sorensen, Neil R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Missert, Nancy A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-05-01

    We have developed and characterized novel in-situ corrosion sensors to monitor and quantify the corrosive potential and history of localized environments. Embedded corrosion sensors can provide information to aid health assessments of internal electrical components including connectors, microelectronics, wires, and other susceptible parts. When combined with other data (e.g. temperature and humidity), theory, and computational simulation, the reliability of monitored systems can be predicted with higher fidelity.

  2. Evaluation of steel corrosion by numerical analysis

    OpenAIRE

    Kawahigashi, Tatsuo

    2017-01-01

    Recently, various non-destructive and numerical methods have been used and many cases of steel corrosion are examined. For example, methods of evaluating corrosion through various numerical methods and evaluating macrocell corrosion and micro-cell corrosion using measurements have been proposed. However, there are few reports on estimating of corrosion loss with distinguishing the macro-cell and micro-cell corrosion and with resembling an actuality phenomenon. In this study, for distinguishin...

  3. 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.

  4. 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.)

  5. 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 ...

  6. Shadow Corrosion Mechanism of Zircaloy

    International Nuclear Information System (INIS)

    Ullberg, Mats; Lysell, Gunnar; Nystrand, Ann-Charlotte

    2004-02-01

    Local corrosion enhancement appears on zirconium-base alloys in-core in boiling water reactors when the zirconium alloy is in close proximity to another metal. The visual appearance often resembles a shadow of the other component. The phenomenon is therefore referred to as 'shadow corrosion'. Shadow corrosion has been known for more than 25 years. Mechanisms based on either galvanic corrosion or local radiolysis effects have been proposed as explanations. Both types of mechanism have seemed to explain some facets of the phenomenon. Normally, shadow corrosion is of no practical significance. However, an enhanced and potentially serious form of shadow corrosion was discovered in 1996. This discovery stimulated new experiments that fully supported neither of the longstanding theories. Thus, there is till now no generally accepted understanding of the shadow corrosion phenomenon. The aim of the present investigation was to analyse the available data and to identify, if possible, a plausible mechanism of shadow corrosion. It was found that the experimental evidence is, with a few exceptions, remarkably consistent with a galvanic mechanism. The main exception is that shadow corrosion may occur also when the two metals are nominally electrically insulated. One way to account for the main exception could be to invoke the effect of photoconductivity. Photoconductivity results when a semiconductor or an insulator is irradiated with photons of UV or higher energy. The photons elevate electrons from the valence band to the conduction band, thereby raising the electron conductivity of the solid. In particular, photoconductivity lowers the electrical resistance of the normally insulating oxide on zirconium base alloys. Photoconductivity therefore also has the potential to explain why shadow corrosion is only seen in, or in proximity to, a nuclear reactor core. The suggested mechanism of shadow corrosion can be tested in a reasonably simple experiment in a research reactor

  7. 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]).

  8. Fatigue crack propagation of acrylic bone cements. Influence of the radio-opaque agents; Propagacion de grietas por fatiga de cementos oseos acrilicos. Influencia de los agentes radiopacos

    Energy Technology Data Exchange (ETDEWEB)

    Ginebra, M. P.; Albuixech, L.; Fernandez-Barragan, E.; Gil, F. J.; Planell, J. A.; San Roman, J.; Vazquez, B.

    2001-07-01

    In this work the 2,5-diiodo-8-quinolyl methacrylate (IHQM), is proposed as a new radiopaque agent. The addition of the iodine containing methacrylate provided a statistically significant increase in the tensile strength, fracture toughness and ductility, with respect to the barium sulphate containing cement. This effect was attributed to the fact that the use of a radiopaque monomer eliminated the porosity associated to the barium sulphate particles. However, since fatigue resistance is one of the main properties required to ensure a good long-term performance of permanent pros these, as is the case of acrylic bone cements, it is important to compare the fatigue properties of this new bone cement formulation with the radiolucent and the BaSO{sub 4} containing bone cements. The results show that the absence of inorganic particles with no matrix adhesion plays a negative role when the fatigue crack propagation is considered. (Author) 26 refs.

  9. Hydrothermal alkaline stability of bentonite barrier by concrete interstitial wastes; Alteracion alcalina hidrotermal de la barrera de bentonita por aguas intersticiales de cementos

    Energy Technology Data Exchange (ETDEWEB)

    Leguey Jimenez, S; Cuevas Rodriguez, J; Ramirez Martin, S; Vigil de la villa Mencia, R.; Martin Barca, M [Universidad Autonoma de Madrid, Madrid (Spain)

    2002-07-01

    At present, the main source of High Level radioactive Waste (HLW) is the electrical energy production during all the steps of developing. In almost all the countries with nuclear programs, the option for the final management of HLW is the Deep Geological Repository (DGR) based on the concept of multi barrier. According to this concept, the waste is isolated from biosphere by the interposition of confinement barriers. Two of the engineering barriers in the Spanish design of DGR in granitic rock are compacted bentonite and concrete. The bentonite barrier is the backfilling and sealing material for the repository gallery, because of its mechanical and physico-chemical properties. The main qualities of concrete as a component of a multi barrier system are its low permeability, mechanical resistance and chemical properties. With regard to chemical composition of concrete, the alkaline nature of cement pore water lowers the solubility of many radioactive elements. However, structural transformation in smectite, dissolution or precipitation of minerals and, consequently, changes in the bentonite properties could occurs in the alkaline conditions generated by the cement degradation. The main objective of the present work is to evaluate the effect of concrete in the stability of Spanish reference bentonite (La Serrata of Nijar, Almeria, Spain) in conditions similar to those estimated in a DGR in granitic rock. Because of the main role of bentonite barrier in the global performance of the repository, the present study is essential to guarantee its security. (Author)

  10. Corrosion mapping in pipelines

    International Nuclear Information System (INIS)

    Zscherpel, U.; Alekseychuk, O.; Bellon, C.; Ewert, U.; Rost, P.; Schmid, M.

    2002-01-01

    In a joint research project, BASF AG and BAM analyzed the state of the art of tangential radiography of pipes and developed more efficient methods of evaluation. Various PC applications were developed and tested: 1. A program for routine evaluation of digital radiographic images. 2. 3D simulation of the tangential projection of pipes for common radiation sources and various different detectors. 3. Preliminary work on combined evaluation of digital projections and wall thickness changes in radiation direction resulted in a new manner of image display, i.e. the so-called 'corrosion mapping', in which the wall thickness is displayed as a 2D picture above the pipe surface [de

  11. Microbiologically Influenced Corrosion

    Science.gov (United States)

    2015-11-05

    high in water content, are less corrosive owing to their elevated viscosity and resulting low conductivity (᝺-7 S/cm) [30]. Asphaltenes and resins...wet surface to a water-wet surface. Sludge deposits are combinations of hydrocarbons, sand, clay , corTosion prod- ucts, and biomass that can reach 50...fine clay sun·ounded by a film of water. Under low flow conditions, these particles precipitate and form a sludge deposit. 27.4 TESTING 27 .4.1 A

  12. Corrosion of Ceramic Materials

    Science.gov (United States)

    Opila, Elizabeth J.; Jacobson, Nathan S.

    1999-01-01

    Non-oxide ceramics are promising materials for a range of high temperature applications. Selected current and future applications are listed. In all such applications, the ceramics are exposed to high temperature gases. Therefore it is critical to understand the response of these materials to their environment. The variables to be considered here include both the type of ceramic and the environment to which it is exposed. Non-oxide ceramics include borides, nitrides, and carbides. Most high temperature corrosion environments contain oxygen and hence the emphasis of this chapter will be on oxidation processes.

  13. Corrosion management in nuclear industry

    International Nuclear Information System (INIS)

    Kamachi Mudali, U.

    2012-01-01

    Corrosion is a major degradation mechanism of metals and alloys which significantly affects the global economy with an average loss of 3.5% of GDP of several countries in many important industrial sectors including chemical, petrochemical, power, oil, refinery, fertilizer etc. The demand for higher efficiency and achieving name plate capacity, in addition to ever increasing temperatures, pressures and complexities in equipment geometry of industrial processes, necessitate utmost care in adopting appropriate corrosion management strategies in selecting, designing, fabricating and utilising various materials and coatings for engineering applications in industries. Corrosion control and prevention is an important focus area as the savings achieved from practicing corrosion control and prevention would bring significant benefits to the industry. Towards this, advanced corrosion management strategies starting from design, manufacturing, operation, maintenance, in-service inspection and online monitoring are essential. At the Indira Gandhi Centre for Atomic Research (IGCAR) strategic corrosion management efforts have been pursued in order to provide solutions to practical problems emerging in the plants, in addition to innovative efforts to provide insight into mechanism and understanding of corrosion of various engineering materials and coatings. In this presentation the author highlights how the nuclear industry benefited from the practical approach to successful corrosion management, particularly with respect to fast breeder reactor programme involving both reactor and associated reprocessing plants. (author)

  14. New technologies - new corrosion problems

    International Nuclear Information System (INIS)

    Heitz, E.

    1994-01-01

    Adequate resistance of materials to corrosion is equally important for classical and for new technologies. This article considers the economic consequences of corrosion damage and, in addition to the long-known GNP orientation, presents a new approach to the estimation of the costs of corrosion and corrosion protection via maintenance and especially corrosion-related maintenance. The significance of ''high-tech'', ''medium-tech'' and ''low-tech'' material and corrosion problems is assessed. Selected examples taken from new technologies in the areas of power engineering, environmental engineering, chemical engineering, and biotechnology demonstrate the great significance of the problems. It is concluded that corrosion research and corrosion prevention technology will never come to an end but will constantly face new problems. Two technologies are of particular interest since they focus attention on new methods of investigation: microelectronics and final disposal of radioactive wastes. The article closes by considering the importance of the transfer of experience and technology. Since the manufacturs and operators of machines and plant do not generally have access to the very latest knowledge, they should be kept informed through advisory services, experimental studies, databases, and further education. (orig.) [de

  15. Corrosion inhibitors. Manufacture and technology

    International Nuclear Information System (INIS)

    Ranney, M.W.

    1976-01-01

    Detailed information is presented relating to corrosion inhibitors. Areas covered include: cooling water, boilers and water supply plants; oil well and refinery operations; fuel and lubricant additives for automotive use; hydraulic fluids and machine tool lubes; grease compositions; metal surface treatments and coatings; and general processes for corrosion inhibitors

  16. DPC materials and corrosion environments.

    Energy Technology Data Exchange (ETDEWEB)

    Ilgen, Anastasia Gennadyevna; Bryan, Charles R.; Teich-McGoldrick, Stephanie; Hardin, Ernest

    2014-10-01

    After an exposition of the materials used in DPCs and the factors controlling material corrosion in disposal environments, a survey is given of the corrosion rates, mechanisms, and products for commonly used stainless steels. Research needs are then identified for predicting stability of DPC materials in disposal environments. Stainless steel corrosion rates may be low enough to sustain DPC basket structural integrity for performance periods of as long as 10,000 years, especially in reducing conditions. Uncertainties include basket component design, disposal environment conditions, and the in-package chemical environment including any localized effects from radiolysis. Prospective disposal overpack materials exist for most disposal environments, including both corrosion allowance and corrosion resistant materials. Whereas the behavior of corrosion allowance materials is understood for a wide range of corrosion environments, demonstrating corrosion resistance could be more technically challenging and require environment-specific testing. A preliminary screening of the existing inventory of DPCs and other types of canisters is described, according to the type of closure, whether they can be readily transported, and what types of materials are used in basket construction.

  17. 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

  18. Alternativas de reducción de las emisiones de dióxido de carbono (CO2 en la producción de cemento. Propuesta de un modelo de evaluación

    Directory of Open Access Journals (Sweden)

    Ana Gessa Perera

    2016-03-01

    Full Text Available La combinación óptima de las medidas disponibles de ajuste de emisiones de dióxido de carbono (CO2 para compatibilizar los objetivos de producción con las exigencias medioambientales requiere planteamientos en la planificación de la producción industrial, con incorporación de nuevos parámetros y variables que permitan evaluar el impacto de las decisiones operativas sobre dichas emisiones, sujetas a las limitaciones del Protocolo de Kyoto. Tras realizar un análisis detallado del potencial de mejora de las alternativas disponibles para reducir las emisiones de CO2 derivadas de la producción de cemento, abordamos en este trabajo las decisiones de optimización con un enfoque integrado, empleando un modelo de programación lineal que contempla conjuntamente las alternativas viables para reducir las emisiones y considerando tanto las derivadas de la aplicación de los mecanismos de flexibilidad del Protocolo de Kyoto como las destinadas a mejorar los productos y los procesos productivos. Su aplicación permitirá mejorar el proceso de toma de decisiones, al permitir considerar diferentes escenarios y obtener información relevante a través del análisis postoptimal. Se incluye, entre otras alternativas, la cantidad máxima a pagar por las instalaciones en el mercado de derechos para emitir una tonelada adicional de CO2 o posibles cambios en el mix de producción para aumentar la rentabilidad, tanto relativos a tipo de productos como a cantidad a fabricar de los mismos.

  19. 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

  20. Fatigue and Corrosion in Metals

    CERN Document Server

    Milella, Pietro Paolo

    2013-01-01

    This textbook, suitable for students, researchers and engineers, gathers the experience of more than 20 years of teaching fracture mechanics, fatigue and corrosion to professional engineers and running experimental tests and verifications to solve practical problems in engineering applications. As such, it is a comprehensive blend of fundamental knowledge and technical tools to address the issues of fatigue and corrosion. The book initiates with a systematic description of fatigue from a phenomenological point of view, since the early signs of submicroscopic damage in few surface grains and continues describing, step by step, how these precursors develop to become mechanically small cracks and, eventually, macrocracks whose growth is governed by fracture mechanics. But fracture mechanics is also introduced to analyze stress corrosion and corrosion assisted fatigue in a rather advanced fashion. The author dedicates a particular attention to corrosion starting with an electrochemical treatment that mechanical e...

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

    Directory of Open Access Journals (Sweden)

    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.

  2. IN DRIFT CORROSION PRODUCTS

    Energy Technology Data Exchange (ETDEWEB)

    D.M. Jolley

    1999-12-02

    As directed by a written development plan (CRWMS M&O 1999a), a conceptual model for steel and corrosion products in the engineered barrier system (EBS) is to be developed. The purpose of this conceptual model is to assist Performance Assessment Operations (PAO) and its Engineered Barrier Performance Department in modeling the geochemical environment within a repository drift, thus allowing PAO to provide a more detailed and complete in-drift geochemical model abstraction and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near-Field Environment (NFE) Revision 2 (NRC 1999). This document provides the conceptual framework for the in-drift corrosion products sub-model to be used in subsequent PAO analyses including the EBS physical and chemical model abstraction effort. This model has been developed to serve as a basis for the in-drift geochemical analyses performed by PAO. However, the concepts discussed within this report may also apply to some near and far-field geochemical processes and may have conceptual application within the unsaturated zone (UZ) and saturated zone (SZ) transport modeling efforts.

  3. Successful implant placement in a Case of Florid Cemento-osseous Dysplasia: a case report and literature review.

    Science.gov (United States)

    Esfahanizadeh, Nasrin; Yousefi, Hila

    2018-02-06

    Florid cemento-osseus dysplasia (FCOD) has been described as a reactive process in which normal bone is replaced by fibrous connective tissues and cementum-like materials. Radiographically it appears as dense, lobulated masses, often occurring bilaterally with symmetric involvement. In this case report a successful implant placement has been reported in a 62-year-old Caucasian woman with a chief complaint of mandibular partial edentulous. Radiographic images showed the bilateral radio-opaque lesions in edentulous regions of mandible, and mandibular anterior teeth alike. All mandibular teeth were vital and no root resorption was detected. The findings of X-ray images were attributable to FCOD. A highly conservative step-by-step two-stage implant surgery was performed. After 6 months the implants loaded with fixed prosthesis. 2, 4,6,12 and 18 months after the surgery radiographic images were taken, which revealed an optimal functional rehabilitation and complete integration of implants. This report confirms that treating the edentulous area near the FCOD lesions could be planned, if conservative and step-by-step implant placement been considered. To the best of our knowledge, a case of FCOD with successful implant placement has not been reported previously. More studies in more patients are needed to confirm results of such a therapeutic modality.

  4. Human permanent teeth are divided into two parts at the cemento-enamel junction in the divine golden ratio.

    Science.gov (United States)

    Anand, Rahul; Sarode, Sachin C; Sarode, Gargi S; Patil, Shankargouda

    2017-01-01

    The aim of this study is to find out whether tooth length (crown length + root length) follows the rule of most divine and mysterious phi (ϕ) or the golden ratio. A total of 140 teeth were included in the study. The crown-root ratio was manually calculated using vernier caliper and its approximation to golden ratio or the divine number phi (ϕ) was examined. The average root-crown ratio (R/C) for maxillary central incisor was 1.627 ± 0.04, and of its antagonist, mandibular central incisor was 1.628 ± 0.02. The tooth-root ratio (T/R) for the same was 1.609 ± 0.016 and 1.61 ± 0.008, respectively. Similar values were appreciated for lateral incisors where the R/C ratio in the maxillary and mandibular teeth was 1.632 ± 0.015 and 1.641 ± 0.012 and the T/R ratio was 1.606 ± 0.005 and 1.605 ± 0.005, respectively. On measuring the tooth length in linear fashion from the cusp tip to the root apex, we found that the tooth was divided into two parts at the cemento-enamel junction in the golden ratio. This information can be exploited in restorative and implant dentistry in future.

  5. Estudio de la trabajabilidad de algunos morteros de cemento para la albañilería

    Directory of Open Access Journals (Sweden)

    Valdehita Roselló, M. Teresa

    1977-03-01

    Full Text Available In this article, the characteristics are described which a good mortar must have, comparing the water retaining capacity of the different types of mortar, as well as the necessary strength for making them slide against their internal cohesion (shearing threshold. For this, different proportions, cements, lime, aggregates, water and different additives were used, which met the appropriate standards, making the necessary tests, and the results of which have been gathered in extremely useful tables.Se describen en este artículo las características que debe reunir un buen mortero, comparando la capacidad de retención de agua de las diferentes clases de aquéllos, así como la fuerza necesaria para hacerlos deslizar en contra de su cohesión interna (umbral de cizalladura. Para ello se han utilizado dosificaciones, cementos, cales, áridos, agua y aditivos diversos que cumplan las debidas normas de recepción, realizándose los ensayos que han sido necesarios y cuyos resultados se han recogido en tablas de gran utilidad.

  6. Celulitis por citomegalovirus

    Directory of Open Access Journals (Sweden)

    A. Ruiz Lascano

    2002-12-01

    Full Text Available Las lesiones cutáneas por citomegalovirus (CMV son infrecuentes y a menudo una manifestación tardía de una enfermedad sistémica, que generalmente anuncia un curso fatal. Comunicamos un caso de celulitis por CMV: una mujer de 70 años con trasplante renal efectuado 1 mes antes de la consulta, terapia inmunosupresora con ciclosporina A y metilprednisona. La paciente ingresó por fiebre, dolor e impotencia funcional en pierna derecha. Comprobamos la existencia de una placa de 8 por 4 cm eritematoedematosa. La tratamos con antibióticos sin mejoría, por lo que realizamos un estudio histopatológico de piel que mostró cambios citopáticos compatibles con infección por CMV. Los cultivos bacteriológicos y micológicos fueron negativos. La inmunohistoquímica específica para CMV y el estudio de reacción en cadena de la polimerasa (PCR de la biopsia de piel fueron positivas, al igual que la antigenemia. El tratamiento con ganciclovir produjo la mejoría del cuadro clínico. En la literatura revisada no hemos encontrado la celulitis como manifestación de enfermedad cutánea por CMV.

  7. 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

  8. Corrosion detection of nanowires by magnetic sensors

    KAUST Repository

    Kosel, Jü rgen; Amara, Selma; Ivanov, Iurii; Blanco, Mario

    2017-01-01

    Disclosed are various embodiments related to a corrosion detection device for detecting corrosive environments. A corrosion detection device comprises a magnetic sensor and at least one magnetic nanowire disposed on the magnetic sensor. The magnetic sensor is configured to detect corrosion of the one or more magnetic nanowires based at least in part on a magnetic field of the one or more magnetic nanowires.

  9. 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.

  10. Corrosion detection of nanowires by magnetic sensors

    KAUST Repository

    Kosel, Jürgen

    2017-10-05

    Disclosed are various embodiments related to a corrosion detection device for detecting corrosive environments. A corrosion detection device comprises a magnetic sensor and at least one magnetic nanowire disposed on the magnetic sensor. The magnetic sensor is configured to detect corrosion of the one or more magnetic nanowires based at least in part on a magnetic field of the one or more magnetic nanowires.

  11. A Multifunctional Coating for Autonomous Corrosion Control

    Science.gov (United States)

    Calle, Luz M.; Li, Wenyan; Buhrow, Jerry W.; Jolley, Scott t.

    2011-01-01

    Nearly all metals and their alloys are subject to corrosion that causes them to lose their structural integrity or other critical functionality. Protective coatings are the most commonly used method of corrosion control. However, progressively stricter environmental regulations have resulted in the ban of many commercially available corrosion protective coatings due to the harmful effects of their solvents or corrosion inhibitors. This work concerns the development of a multifunctional smart coating for the autonomous control of corrosion. This coating is being developed to have the inherent ability to detect the chemical changes associated with the onset of corrosion and respond autonomously to indicate it and control it. The multi-functionality of the coating is based on microencapsulation technology specifically designed for corrosion control applications. This design has, in addition to all the advantages of existing microcapsulation designs, the corrosion controlled release function that triggers the delivery of corrosion indicators and inhibitors on demand, only when and where needed. Microencapsulation of self-healing agents for autonomous repair of mechanical damage to the coating is also being pursued. Corrosion indicators, corrosion inhibitors, as well as self-healing agents, have been encapsulated and dispersed into several paint systems to test the corrosion detection, inhibition, and self-healing properties of the coating. Key words: Corrosion, coating, autonomous corrosion control, corrosion indication, corrosion inhibition, self-healing coating, smart coating, multifunctional coating, microencapsulation.

  12. Improvement of PWR reliability by corrosion prevention

    International Nuclear Information System (INIS)

    Takamatsu, Hiroshi

    1999-01-01

    Since first PWR in Japan started commercial operation in 1970, we have encountered the various modes of corrosion on primary and secondary side components. We have paid much efforts for resolving these corrosion problems, that is, investigating the causes of corrosion and establishing the countermeasures for these corrosion. We summarize these efforts in this article. (author)

  13. 49 CFR 172.442 - CORROSIVE label.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false CORROSIVE label. 172.442 Section 172.442... SECURITY PLANS Labeling § 172.442 CORROSIVE label. (a) Except for size and color, the CORROSIVE label must... CORROSIVE label must be white in the top half and black in the lower half. [Amdt. 172-123, 56 FR 66259, Dec...

  14. High temperature corrosion of metals

    International Nuclear Information System (INIS)

    Quadakkers, W.J.; Schuster, H.; Ennis, P.J.

    1988-08-01

    This paper covers three main topics: 1. high temperature oxidation of metals and alloys, 2. corrosion in sulfur containing environments and 3. structural changes caused by corrosion. The following 21 subjects are discussed: Influence of implanted yttrium and lanthanum on the oxidation behaviour of beta-NiA1; influence of reactive elements on the adherence and protective properties of alumina scales; problems related to the application of very fine markers in studying the mechanism of thin scale formation; oxidation behaviour of chromia forming Co-Cr-Al alloys with or without reactive element additions; growth and properties of chromia-scales on high-temperature alloys; quantification of the depletion zone in high temperature alloys after oxidation in process gas; effects of HC1 and of N2 in the oxidation of Fe-20Cr; investigation under nuclear safety aspects of Zircaloy-4 oxidation kinetics at high temperatures in air; on the sulfide corrosion of metallic materials; high temperature sulfide corrosion of Mn, Nb and Nb-Si alloys; corrosion behaviour or NiCrAl-based alloys in air and air-SO2 gas mixtures; sulfidation of cobalt at high temperatures; preoxidation for sulfidation protection; fireside corrosion and application of additives in electric utility boilers; transport properties of scales with complex defect structures; observations of whiskers and pyramids during high temperature corrosion of iron in SO2; corrosion and creep of alloy 800H under simulated coal gasification conditions; microstructural changes of HK 40 cast alloy caused by exploitation in tubes in steam reformer installation; microstructural changes during exposure in corrosive environments and their effect on mechanical properties; coatings against carburization; mathematical modeling of carbon diffusion and carbide precipitation in Ni-Cr-based alloys. (MM)

  15. 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 ...

  16. Cracking and corrosion recovery boiler

    Energy Technology Data Exchange (ETDEWEB)

    Suik, H. [Tallinn Technical University, Horizon Pulp and Paper, Tallinn (Estonia)

    1998-12-31

    The corrosion of heat surfaces and the cracking the drums are the main problems of the recovery boiler. These phenomena have been appeared during long-term operation of boiler `Mitsubishi - 315` erected at 1964. Depth of the crack is depending on the number of shutdowns and on operation time. Corrosion intensity of different heat surfaces is varying depend on the metal temperature and the conditions at place of positioning of tube. The lowest intensity of corrosion is on the bank tubes and the greatest is on the tubes of the second stage superheater and on the tubes at the openings of air ports. (orig.) 5 refs.

  17. Corrosion-resistant coating development

    Energy Technology Data Exchange (ETDEWEB)

    Stinton, D.P.; Kupp, D.M.; Martin, R.L. [Oak Ridge National Lab., TN (United States)

    1997-12-01

    SiC-based heat exchangers have been identified as the prime candidate material for use as heat exchangers in advanced combined cycle power plants. Unfortunately, hot corrosion of the SiC-based materials created by alkali metal salts present in the combustion gases dictates the need for corrosion-resistant coatings. The well-documented corrosion resistance of CS-50 combined with its low (and tailorable) coefficient of thermal expansion and low modulus makes CS-50 an ideal candidate for this application. Coatings produced by gelcasting and traditional particulate processing have been evaluated.

  18. Cracking and corrosion recovery boiler

    Energy Technology Data Exchange (ETDEWEB)

    Suik, H [Tallinn Technical University, Horizon Pulp and Paper, Tallinn (Estonia)

    1999-12-31

    The corrosion of heat surfaces and the cracking the drums are the main problems of the recovery boiler. These phenomena have been appeared during long-term operation of boiler `Mitsubishi - 315` erected at 1964. Depth of the crack is depending on the number of shutdowns and on operation time. Corrosion intensity of different heat surfaces is varying depend on the metal temperature and the conditions at place of positioning of tube. The lowest intensity of corrosion is on the bank tubes and the greatest is on the tubes of the second stage superheater and on the tubes at the openings of air ports. (orig.) 5 refs.

  19. Assessing resistance of stabilized corrosion resistant steels to intergranular corrosion

    International Nuclear Information System (INIS)

    Karas, A.; Cihal, V. Jr.; Vanek, V.; Herzan, J.; Protiva, K.; Cihal, V.

    1987-01-01

    Resistance to intergranular corrosion was determined for four types of titanium-stabilized steels from the coefficients of stabilization efficiency according to the degree the chemical composition was known. The ATA SUPER steel showed the highest resistance parameter value. The resistance of this type of steel of a specific composition, showing a relatively low value of mean nitrogen content was compared with steel of an optimized chemical composition and with low-carbon niobium stabilized, molybdenum modified steels. The comparison showed guarantees of a sufficient resistance of the steel to intergranular corrosion. The method of assessing the resistance to intergranular corrosion using the calculation of the minimum content of Cr', i.e., the effective chromium content, and the maximum effective carbon content C' giving the resistance parameter k seems to be prospective for practical use in the production of corrosion resistant steels. (author). 1 tab., 5 figs., 15 refs

  20. 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.

  1. pitting corrosion susceptibility pitting corrosion susceptibility of aisi

    African Journals Online (AJOL)

    eobe

    2DEPARTMENT OF MECHANICAL ENGINEERING, UNIVERSITY OF BENIN, BENIN- CITY, EDO STATE, NIGERIA. E-mail addresses: ... fluids and aggressive chemicals. Pitting corrosion ... the kitchen, food manufacturing and dispensing and.

  2. Corrosion resistant ceramic materials

    Science.gov (United States)

    Kaun, T.D.

    1996-07-23

    Ceramic materials are disclosed which exhibit stability in severely-corrosive environments having high alkali-metal activity, high sulfur/sulfide activity and/or molten halides at temperatures of 200--550 C or organic salt (including SO{sub 2} and SO{sub 2}Cl{sub 2}) at temperatures of 25--200 C. These sulfide ceramics form stoichiometric (single-phase) compounds with sulfides of Ca, Li, Na, K, Al, Mg, Si, Y, La, Ce, Ga, Ba, Zr and Sr and show melting-points that are sufficiently low and have excellent wettability with many metals (Fe, Ni, Mo) to easily form metal/ceramic seals. Ceramic compositions are also formulated to adequately match thermal expansion coefficient of adjacent metal components. 1 fig.

  3. Mortar fights acid corrosion

    Energy Technology Data Exchange (ETDEWEB)

    1982-05-14

    The burning of coal or oil to produce heat required to operate a power boiler also generates a severe corrosion problem within the interior of the duct and stacks used to emit the flue gas into the atmosphere. How can concrete and steel be protected from the effects of acid attack, when the acids are carried in a gas form, or come into direct contact with the steel or concrete from spillage or immersion conditions. Industry in North America has found that the solution to this problem is to build an outside concrete column, in this case of Portland cement, and inside that column, build a totally independent brick liner bonded with Sauereisen mortar.

  4. Erosion--corrosion

    International Nuclear Information System (INIS)

    Vyas, B.

    1978-01-01

    The deterioration of materials by corrosion or erosion by itself presents a formidable problem and for this reason investigators have studied these two phenomena independently. In fact, there are very few systematic studies on E-C and the majority of references mention it only in passing. In most real systems, however, the two destructive processes take place simultaneously, hence the purpose of this review is to present the various interactions between the chemical and mechanical agents leading to accelerated degradation of the material. The papers cited in the review are those that lead to a better understanding of the process involved in the accelerated rate of material loss under E-C conditions

  5. Corrosion resistant ceramic materials

    Science.gov (United States)

    Kaun, Thomas D.

    1996-01-01

    Ceramic materials which exhibit stability in severely-corrosive environments having high alkali-metal activity, high sulfur/sulfide activity and/or molten halides at temperatures of 200.degree.-550.degree. C. or organic salt (including SO.sub.2 and SO.sub.2 Cl.sub.2) at temperatures of 25.degree.-200.degree. C. These sulfide ceramics form stoichiometric (single-phase) compounds with sulfides of Ca, Li, Na, K, Al, Mg, Si, Y, La, Ce, Ga, Ba, Zr and Sr and show melting-points that are sufficiently low and have excellent wettability with many metals (Fe, Ni, Mo) to easily form metal/ceramic seals. Ceramic compositions are also formulated to adequately match thermal expansion coefficient of adjacent metal components.

  6. Critical Study of Corrosion Damaged Concrete Structures

    OpenAIRE

    Sallehuddin Shah Ayop; John Cairns

    2013-01-01

    Corrosion of steel reinforcement in concrete is one of the major problems with respect to the durability of reinforced concrete structures. The degradation of the structure strength due to reinforcement corrosion decreases its design life. This paper presents the literature study on the influence of the corrosion on concrete structure starting from the mechanism of the corrosion until the deterioration stage and the structural effects of corrosion on concrete structures.

  7. Corrosion testing and prediction in SCWO environments

    International Nuclear Information System (INIS)

    Kriksunov, L.B.; Macdonald, D.D.

    1995-01-01

    The authors review recent advances in corrosion monitoring and modeling in SCWO systems. Techniques and results of experimental corrosion measurements at high temperatures are presented. Results of modeling corrosion in high subcritical and supercritical aqueous systems indicate the primary importance of density of water in corrosion processes. A phenomenological model has been developed to simulate corrosion processes at nearcritical and supercritical temperatures in SCWO systems. They discuss as well the construction of Pourbaix diagrams for metals in SCW

  8. 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.

  9. Durabilidad del hormigón: Acción del agua de mar sobre un cemento portland resistente a los sulfatos. Influencia de la adición de escorias y de cenizas volantes

    Directory of Open Access Journals (Sweden)

    Gaspar Tebar, Demetrio

    1991-12-01

    Full Text Available This article, is part of a long time ICCET investigation programs studies the variation of the mechanical resistance to flexotraction 1: 3 normalized mortar with 1 x 1 x6cm dimension, using sulphate-resistent portland cement mixed with 15-35-60 and 70% parts of a furnace slag, a fiy ash or silica sand. The samples were submitted to the action of AS.T.M. artificial sea water and filtered potable water during several time periods (3 years for the first and second addition and 1 year for the third after the cured period (1 day at 100% R.H. and 21 days inside filtered potable water. The evolution of the ionic concentration of the aggressive solutions were studied and also the new phases formed with its new structural composition. Finally, and account is given of the researches and first results about the behavior of the mortars and concretes made with two different industrial cements and submitted to the natural sea water at a selected area of the marine Huelva-Port.

    En este artículo, que forma parte de un Proyecto de Investigación del ICCETa largo plazo, se estudia la variación de las resistencias mecánicas —a flexotracción— de las probetas de mortero normalizado (1:3, de 1x1x6 cm, mezclando un cemento portland resistente a los sulfates y sus mezclas (cemento/adición = 85/15 - 65/35 - 40/60 y 30/70, en peso, con una escoria, ceniza volante y arena silícea. Se someten a la acción de agua del mar artificial ASTM y de agua potable filtrada durante diversos períodos de tiempo (hasta 3 años para las dos primeras adiciones, y hasta 1 año para la tercera después de la fase de curado (1 día en cámara húmeda y 21 días bajo agua potable filtrada. Se estudia la evolución de la concentración iónica de los medios en donde han estado sumergidas dichas probetas de mortero, las características químicas de las nuevas fases sólidas formadas y la composición estructural de estas nuevas fases sólidas. Por último, se da cuenta

  10. Reciclaje de escoria granulada de fundición (EGF) como sustitución de parte del cemento en hormigón

    OpenAIRE

    Ceccato,D.M.; Masuero,A.B.; Moraes,C.A.M.; Vilela,A.C.F.

    2009-01-01

    El reciclaje de residuos sólidos industriales se ha vuelto una práctica indispensable en la preservación de los recursos naturales, en la minimización de los costos y en la reducción del impacto ambiental. La utilización de materiales alternativos en la industria de la construcción civil es una práctica económicamente atractiva y ambientalmente correcta. Siendo así, el empleo de escorias como materia prima en carreteras, hormigón y cemento ya es una práctica corriente, en la cual, el destino ...

  11. Metallurgy of stress corrosion cracking

    International Nuclear Information System (INIS)

    Donovan, J.A.

    1973-01-01

    The susceptibility of metals and alloys to stress corrosion is discussed in terms of the relationship between structural characteristics (crystal structure, grains, and second phases) and defects (vacancies, dislocations, and cracks) that exist in metals and alloys. (U.S.)

  12. Heated Aluminum Tanks Resist Corrosion

    Science.gov (United States)

    Johnson, L. E.

    1983-01-01

    Simple expedient of heating foam-insulated aluminum alloy tanks prevents corrosion by salt-laden moisture. Relatively-small temperature difference between such tank and surrounding air will ensure life of tank is extended by many years.

  13. Contribución al estudio de la resistencia química de los cementos. Comportamiento mecánico de un cemento portland resistente al yeso (2.ª parte

    Directory of Open Access Journals (Sweden)

    Gaspar-Tébar, Demetrio

    1985-12-01

    /serie/edad/disolución, hechas con un cemento portland industrial resistente al yeso (P-450-Y, según RC-75, sumergidas en agua potable filtrada y en las siguientes disoluciones agresivas: saturada de sulfato de calcio, de MgSO4.7 H2O (3,22 g/l, de MgSO42O (32,2 g/l, saturada de sulfato de calcio más MgSO4.7 H2O (3,22 g/l, saturada de sulfato de calcio más MgSO4.7 H2O (32,2 g/l y agua de mar artificial ASTM D 1141-75 durante 56 - 90- 180 - 360 - 540 - 720 - 900 y 1.080 días, después del período de curado (1 + 21 días. Así misino, se estudia la variación de dichas resistencias mecánicas a flexotracción y compresión de probetas de mortero (1 : 3 de 4 X 4 X 16 cm, a tracción centrifuga de probetas de mortero de 7 X 7 X 28 cm y a flexotracción y compresión de probetas de hormigón de 10 X 10 X 40 cm, hechas con el cemento mencionado (P-450-Y, cuando se sumergen en agua potable y en cinco disoluciones agresivas [disolución saturada de sulfato de calcio, disolución de Na2SO4 (2,1 g/l, disolución de MgSO4.7 H2O (3,22 g/l, disolución de Na2SO4 (3,5 g/l + NaCl (20,0 g/l y agua de mar artificial ASTM D 1141-75] durante 6 – 12 – 18 – 24 - 30 - 36- 42 – 48 - 54 y 60 meses, después del periodo de curado (1 + 30 días. Los resultados obtenidos han permitido establecer una graduación del cemento estudiado según su comportamiento, frente a las mencionadas disoluciones agresivas.

  14. Corrosion resistant neutron absorbing coatings

    Science.gov (United States)

    Choi, Jor-Shan [El Cerrito, CA; Farmer, Joseph C [Tracy, CA; Lee, Chuck K [Hayward, CA; Walker, Jeffrey [Gaithersburg, MD; Russell, Paige [Las Vegas, NV; Kirkwood, Jon [Saint Leonard, MD; Yang, Nancy [Lafayette, CA; Champagne, Victor [Oxford, PA

    2012-05-29

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  15. 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.

  16. Estudios sobre la reactividad de harinas crudas de cemento tratadas con rápidos y diferentes calentamientos

    Directory of Open Access Journals (Sweden)

    Weisweiler, W.

    1988-09-01

    Full Text Available Not available.

    Estudios experimentales llevados a cabo a una temperatura dada de calcinación, sirvieron para observar el efecto de las altas velocidades de calentamiento sobre las reacciones del clinker. Mientras que un aumento de la reactividad de los materiales fue claramente detectada cuando la velocidad pasó de 20 K/min a tomar valores iguales y mayores a 100 K/min, un negativo efecto sobre el Tiempo de Reacción Completa o "Período de Calcinación a Punto" no pudo ser establecido. Considerando además que el tiempo necesario para llevar a la materia prima hasta la temperatura de reacción, es necesariamente un tiempo inefectivo, podrían las plantas productoras de cemento obtener mayores rendimientos en tiempo y espacio, utilizando altas cuotas de calentamiento. Estudios de microscopía probaron que con el aumento de las velocidades de calentamiento, hubo una mayor generación de microcristales incidiendo directamente sobre la molienda y calidad del clinker. [de] Untersuchungen zur Reaktivität van zementrohmehlen nach verschieden schneller Aufheizung. Modellversuche mit linearen Aufheizgeschwindigkeiten solten zeigen, ob bei einer vorgegebenen Brenntemperatur die Verklinkerungsreaktionen beeinfluβt werden können. Während eindeutige Steigerungen der Kalkbindungsraten lediglich zwischen 20 K/min und Aufheizgeschwindigkeiten >=100 K/min nachweisbar waren, konnten negative Auswirkungen auf die Garbranddauern bei keiner Versuchsserie festgestellt werden. Unter Berücksichtigung der zur Aufheizung der Rohstoffe notwendigen Totzeiten, können bei den technischen Zementproduktionsanlagen nach schneller Aufheizung höhere Raum-Zeit-Ausbeuten erreicht werden. Mikroskopische Untersuchungen ergaben, daβ durch Erhöhung der Aufheizraten der Anteil mikrokristalliner Klinkerphasen zunimmt, was sich direkt aut die Zementklinkermahibarkeit und die Klinkerqualität aswirkt.

  17. 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.

  18. Electrocardiografo por computadora

    OpenAIRE

    Tinoco Hernandez, Rosanna; Paredes Bejarano, Margarita; Romero Chaglia, Norman; Yapur Auad, Miguel Eduardo

    2009-01-01

    El presente trabajo trata sobrees el diseño y la implementación de un graficador de señales cardiacas por computadora, para lo cual diseñamos un circuito electrónico capaz de recibir la senal analógica proveniente de la actividad electrica del corazón , amplificarla, y luego convertirla en una señal digital para ser procesada por software y finalmente ser graficada, siendo posible así observar la señal cardiaca en el monitor de un computador como un tren de pulsos. Cabe destacar que par...

  19. 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

  20. Corrosion control in nuclear fuel reprocessing

    International Nuclear Information System (INIS)

    Steele, D.F.

    1986-01-01

    This article looks in detail at tribology-related hazards of corrosion in irradiated fuel reprocessing plants and tries to identify and minimize problems which could contribute to disaster. First, the corrosion process is explained. Then the corrosion aspects at each of four stages in reprocessing are examined, with particular reference to oxide fuel reprocessing. The four stages are fuel receipt and storage, fuel breakdown and dissolution, solvent extraction and product concentration and waste management. Results from laboratory and plant corrosion trails are used at the plant design stage to prevent corrosion problems arising. Operational procedures which minimize corrosion if it cannot be prevented at the design stage, are used. (UK)