Atmospheric corrosion of low carbon steel exposed in a coastal tropical zone of Manabí, Ecuador, was determined. Specimens were exposed at six outdoor exposure sites located at different distances from the sea. The atmosphere is classified as coastal. Wind speed threshold for an increase in chloride deposition rate was determined. The behavior of chloride deposition rate versus distance from the sea is anomalous due to the presence of an estuary. Corrosion by weight loss was evaluated up to 1 year of exposure. Only a slight difference in atmospheric corrosion rate is noticed between wet and dry periods. Chloride deposition interaction with RH–temperature complex and with wind speed shows significant statistical influence on atmospheric corrosion of low carbon steel. Corrosivity category of the atmosphere high (C4) is the most predominant classification level in the zone. Prediction indicates corrosivity category high (C4) will remain up to 20 years of exposure. Different morphologies of corrosion products were identified by SEM. Lepidocrocite, goethite, magnetite, and akaganeite are the main crystalline phases determined by XRD. Protective ability index previously proposed for rust layers is not useful to apply in coastal sites.

The objective of this study was to demonstrate the possibility to obtain concretes in Cuba with values of effective porosity below of 10%, using limestone aggregates with high levels of absorption (higher than 1% in many cases), and values of Sorptivity below of 5 x 10-5 m/s 1/2 as is established in the document prepared by the DURAR Latin Working Group, for structures exposed to very aggressive environments. The experimental results showed that the use of the trial method of capillary absorption of Göran Fagerlund, were obtained concretes with effective porosity below of the 10%, for water/cement ratios of 0.4 and 0.45, but the values of sorptivities were very high. Nevertheless the subsequent use of the trial method of the ASTM C1585, that use cylinders probes with bigger depth and different processing, permits to obtain the desired sorptivity values for water/cement ratios of 0.4 and 0.45 whenever would be fulfilled the Good Practices of the Construction.Keywords: concrete; limestone aggregate; transport properties; permeability; durability. RESUMENEl objetivo del estudio fue demostrar la posibilidad de lograr en Cuba, con el empleo de áridos calizos de elevada absorción (mayores del 1% en muchos casos), hormigones con valores de porosidad efectiva inferiores al 10% y de velocidad de absorción capilar (Sorptividad) inferiores a 5 x 10-5 m/s 1/2 , tal como establece el documento elaborado por la RED DURAR del CYTED para estructuras expuestas a ambientes muy agresivos. Los resultados experimentales mostraron que con la aplicación del método de ensayo de absorción capilar de Göran Fagerlund se obtuvieron porosidades efectivas inferiores al 10% para relaciones agua/cemento de 0,4 y 0,45, pero los valores de sorptividad fueron muy elevados. No obstante la aplicación posterior del método de ensayo de la ASTM C1585 que utiliza probetas de mayor espesor y diferente tratamiento, permitió obtener los valores indicados de sorptividad para relaciones agua/cemento de 0,4; 0,45 siempre que se cumplan las Buenas Prácticas constructivas. Palabras

RESUMENLas edificaciones son obstáculos importantes para el ingreso y distribución del aerosol marino en la atmósfera de clima tropical costero de La Habana. Debido a este efecto de apantallamiento, a escasa distancia del mar se aprecia un considerable decremento en la deposición de iones cloruro. Las partículas de cloruro de mayor tamaño y peso suspendidas en el aerosol pueden depositarse en las inmediaciones del rompiente de las olas. La velocidad promedio anual del viento tuvo un efecto significativo en el incremento de la deposición de cloruros en el sitio de exposición más cercano al mar, donde la influencia de las edificaciones es insignificante y los niveles pronosticados de agresividad corrosiva son alto, muy alto y extremo. La disminución de la temperatura del aire fue el factor climático que tuvo mayor influencia en la deposición de iones cloruro. La penetración del aerosol marino es ocho veces menor en La Habana con relación a otros sitios sin condiciones de apantallamiento. La distribución de la salinidad transportada por el aire dentro de la ciudad es diferente respecto de la encontrada fuera de ésta. ABSTRACTBuilding structures constitute obstacles for the entrance and distribution of marine aerosol in the atmosphere of Havana City (tropical coastal climate). Due to the shielding effect caused by building structures, a considerable decrease in chloride deposition is determined at a short distance from the sea. Heavier and larger-sized chloride aerosol particles can settle down in the vicinity of breaking waves. The annual average wind speed showed significant influence in increasing chloride deposition at the exposure site close to the sea, where the effect of building structures is negligible and the predicted levels of corrosivity of the atmosphere are high, very high and extreme. Air temperature was the main climatic factor influencing chloride deposition (when temperature decreases, chloride deposition increases). Penetration of marine aerosol is eight times lower in Havana City with respect to other sites without obstacles. Airborne salinity distribution inside the city is different than outside the city.Keywords: Marine aerosol, distance from the sea, chloride deposition, shielding condition, corrosivity categories. 88A. Castañeda et al. IntroductionA significant deterioration due to atmospheric corrosion of reinforced concrete structures built with metallic materials, more often used in the construction industry as carbon steel and galvanized steel, is observed in the tropical coastal climate in Havana City. It is a consequence of high (C4), very high (C5) and extreme (CX) corrosivity categories of the atmosphere at coastal locations without shielding conditions (Castañeda et al., 2013(Castañeda et al., , 2014. High corrosivity categories of the atmosphere were expected due to high levels of chloride deposition rate (Cl -DR). However, penetration studies carried out in Cuba and some Latin-American countries about marine aerosol as a factor in the initiation and propagation of atmospheric cor...

Evaluación Comparativa de la corrosión del hormigón armado con acero sin protección y del acero galvanizado en inmersión en caliente Vinícius de Kayser Ortolan AbstractIncreasing the lifespan of structures is of great importance for civil construction, either because of economic aspects or security to the users. Corrosion of reinforcement is one of the most recurring problems, especially in environments with high chloride content. One of the most effective alternatives to protect reinforcement against corrosion is the hot-dip galvanizing of steel bars, with the addition of a zinc coating that is consumed before steel entering in reaction. In this paper, it was investigated the comparison between unprotected steel bars and hot-dip galvanized ones, immersed in four types of concrete with different water/cement ratio, and subjected to accelerated corrosion test executed by the CAIM procedure. It was observed corrosion decreased for all types of concrete, reaching 70.5% of reduction for the richest mixture, showing that the hot-dip galvanizing may be an important alternative to the wired concrete structures, particularly when used in combination with mixtures of greater durability. ResumenEl aumento de la vida útil de las estructuras es de gran importancia para la construcción civil, sea por razones económicas o de seguridad de los usuarios. La corrosión de refuerzo es uno de los problemas más recurrentes, especialmente en entornos con alto contenido de iones cloruro. Una de las alternativas más eficaces para proteger el refuerzo contra la corrosión es la galvanización en caliente de barras de acero, con la adición de recubrimiento de zinc que se ingiere antes del acero entrar en reacción. En este trabajo, fue investigado la comparación entre las barras de acero sin protección y las galvanizadas en caliente, inmersas en cuatro tipos de hormigón con diferentes relaciones agua/cemento, y se somete a procedimiento de ensayo de corrosión acelerada ejecutado por el método CAIM. Se observó la disminución de la corrosión para todos los tipos de hormigón, alcanzando el 70,5% de la reducción de la muestra más rica, mostrando que el galvanizado por inmersión en caliente puede ser una alternativa importante para las estructuras de hormigón, especialmente cuando se utiliza en combinación con mezclas de mayor durabilidad.Palabras clave: Corrosión de la armadura; galvanizado por inmersión en caliente; adhesión; ensayo de flexión.

O aumento da vida útil de estruturas é de grande importância para a construção civil, seja por aspectos econômicos quanto de segurança aos usuários. A corrosão de armaduras é um dos problemas mais recorrentes, principalmente em ambientes com alto teor de cloretos. Uma das alternativas mais eficientes para proteger as armaduras contra a corrosão é a galvanização a quente das barras de aço, com a incorporação de uma camada de zinco que será consumida antes do aço entrar em reação, prolongando a vida útil da estrutura. Porém, esta camada de zinco não deve prejudicar a aderência das barras de aço com o concreto. Neste trabalho, foi investigada esta relação, comparativamente com a armadura sem proteção, com a análise de três diâmetros de barras, 8, 12,5 e 16mm, através de ensaio de flexão em viga, com o procedimento da Rilem, de 1978 [1]. Observou-se que não houve perda de aderência significativa em nenhum dos diâmetros, após análise estatística, mostrando que a aderência entre o concreto e o aço galvanizado a quente não é inferior do que com os aços sem proteção, para estes materiais.