Modeling of chloride diffusion in concrete immersed in CaCl2 and NaCl solutions with account of multi-phase reactions and ionic interactions

It has been found by many researchers that the diffusion behavior of chloride ions in concrete immersed in CaCl2 and NaCl solutions is very different. The conventional Fick's law is not applicable to present the influence of source composition on the chloride diffusion behavior. In this paper, a new model considering the multi-phase reactions and the ionic interactions is proposed. A transformation of the Poisson equation is adopted to describe the ionic flux. The multi-phase reactions are analyzed and the absorption mechanism is introduced in the new model to describe the multi-phase reactions. Experimental test is carried out to reveal the chloride diffusion behaviors in concrete immersed in the two different source solutions. The simulation results of the new model are fitted well with the experimental results, which confirms the validity of the new model.