Mathematical model for chloride diffusion in reinforced concrete structures at Yucatán Península, México

Abstract

Corrosion of reinforcing steel can seriously limit the service life of concrete structures in marine applications. Chloride diffusion is one of the two major problems causing this phenomenon, increasing when the concrete is exposed to a marine environment in coastal areas. The service life of a structure may be divided into two general phases: an initiation period, in which the reinforcing steel surface is still passive as a result of the contact with a high pH medium, in which the aggressive ions penetrate the concrete toward the reinforcing bar, and a propagation period that starts when the chloride ion contamination on the steel surface exceeds the critical threshold level for the passivity breakdown. The aim of this work is to examine the chloride diffusion at the initial period on a marine environment by considering the variability of the diffusion coefficients with inherent parameters of the concrete, exposed during a period of two years in Yucatán, México. A model based on the second Fick's law is proposed; the non-linearity of the problem is taken into account and a numerical procedure based on the finite difference method is developed to solve the set of equations. Comparisons with experimental data are also carried out in order to show the reliability and the effectiveness of the proposed numerical model.