Lattice modeling of chloride diffusion in sound and cracked concrete

Reinforced concrete structures are frequently exposed to aggressive environmental conditions. Most notably, chloride ions from sea water or de-icing salts are potentially harmful since they promote corrosion of steel reinforcement. Concrete cover of sufficient quality and depth can ensure protection of the steel reinforcement. However, it is necessary to study the effects of material heterogeneity and cracking on chloride ingress in concrete. This is done herein by proposing a three-dimensional lattice model capable of simulating chloride transport in saturated sound and cracked concrete. Means of computationally determining transport properties of individual phases in heterogeneous concrete (aggregate, mortar, and interface), knowing the concrete composition and its averaged transport properties, are presented and discussed. Based on numerical experimentation and available literature, a relation between the effective diffusion coefficient of cracked lattice elements and the crack width was adopted. The proposed model is coupled with a lattice fracture model to enable simulation of chloride ingress in cracked concrete. The model was validated on data from the literature, showing good agreement with experimental results.