Numerical Simulation of Chloride-Induced Corrosion Initiation in Reinforced Concrete Structures with Cracks

Steel corrosion is a major problem with concrete structures. For cracked concrete structures exposed to chloride environment, chloride diffusivity through the crack ($D_{cr}$) is higher than that through the concrete matrix ($D_o$), and therefore, the corrosion will occur at an earlier time. In this study, finite-element analysis is performed to study the process of chloride diffusion through cracks. For various values of $D_o$, $D_{cr}$, and crack width, the chloride-concentration distribution is determined. Based on the simulation results, the empirical equation for an equivalent diffusion coefficient ($D_{eq}$) will be derived, which can be used directly in the solution of the one-dimensional diffusion equation to calculate the predicted chloride profile, the corrosion-initiation time, and penetration of corrosion front. The study will provide a convenient but accurate approach for predicting the chloride diffusion, including the corrosion initiation, under real-world situations where cracks are present in a concrete structure.