Approximation by the Finite Element Method to the Preferential Chloride Diffusion through Interfacial Transition Zone in Concrete

Abstract

Chloride diffusion in concrete is a main aspect of reinforced concrete durability. It defines the time required for reinforcement corrosion in marine structures. Concrete porosity is one of the main concerns involved in the process of chloride ingress from the environment into concrete. However, concrete can hardly be considered homogeneous in the meso-level. Natural coarse aggregates are usually less porous than the cementitious matrix, whereas interfacial zones between aggregates and the matrix are the most porous phase in concrete. This aspect is difficult to be experimentally studied, as very little samples need to be collected and analyzed. As an approach, the diffusion process can be simulated with the Finite Element Method (FEM). In this paper, chloride diffusion into concrete is simulated with a 2D FEM model, distinguishing three phases with different porosities in the material. Interfacial zone is identified as preferential path for chloride ingress.