Contribution to estimate of the saturation degree from environmental conditions applied to the reliability analysis of concrete structures subject to chloride attack

Abstract

The durability of structural elements of reinforced concrete subjected to environmental conditions of severe aggressiveness presents itself as one of the main problems faced in civil construction. Among the agents of deterioration of these structures stand out the chlorides ions, widely diffused in marine environment, that cause corrosion of steel reinforcement. The estimated useful life of reinforced concrete elements appears as a fundamental theme in the evaluation of the durability of the structures. Although other processes cause penetration of chloride ions into the concrete, it is practically a consensus that diffusion is the predominant mechanism. A classical model for characterizing chloride penetration is Fick's 2nd Law. Guimarães (2000) demonstrated that the saturation degree (GS) of the concrete is a parameter that exerts a strong influence on the diffusion coefficient of chlorides (D). Although GS measurement methodologies have been developed, they are costly in terms of time and resources. The objective of this work is present estimates of GS based on the environmental conditions to which the material is exposed and later analyze the influence of this parameter in the evaluation of the useful life of structural elements through the reliability. Meteorological and measurement data of GS obtained in two coastal regions are used: Rio Grande, Brazil and Santa Pola, Spain. Models of GS estimation were obtained from the environmental variables of each region and also from both together. The influence of these models on the estimation of useful life through the probability of failure of the structure was then evaluated.