A three-phase model based on boundary element method for simulation of chloride diffusion in concrete

Abstract

Chloride-induced corrosion of steel reinforcements has been identified as one of the main causes of deterioration of concrete structures. A feasible numerical method is required to predict chloride penetration in concrete structures. In this study, a three-phase model of concrete based on the Boundary Element Method (BEM) is proposed to investigate the diffusion and distribution behavior of chlorides in concrete. Compared with the finite element model (FEM), the proposed model has a higher computational efficiency, and a comparison of the simulated chloride concentration with the corresponding experimental data is proved to be reasonable. Furthermore, the parametric analysis is carried out to evaluate the effect of coarse aggregate parameters on chloride diffusion in concrete. The results show that chloride attack was more susceptible to the coarse aggregate content and less affected by the ITZ diffusion coefficient. This may be due to the fact that the volume fraction of aggregates in concrete is much higher than that in the ITZ. In addition, the low permeability of the coarse aggregate hindered the diffusion of chloride ions, while the ITZ around the aggregate accelerated the diffusion of chloride ions. when the aggregate content increases in a certain range from 12.56 % to 50.24 %, the hindering effect of aggregate on chloride ion diffusion is more obvious than the accelerating effect of ITZ.

Keywords

• Three-phase model
• Chloride diffusion
• Coarse aggregate
• Interfacial transition zone
• Boundary element method