Chloride-induced 3D non-uniform corrosion of steel in reinforced concrete considering mesoscale heterogeneities and early-age cracks

Considering that reinforced concrete structures typically work with cracks, this work aims to investigate the chloride-induced non-uniform corrosion of steel by proposing a five-phase cracked reinforced concrete model at mesoscale, including realistic aggregate, matrix, steel, early-age crack, and damage zone. A physically-based 3D mesoscale modeling approach is developed to accommodate all the phases by integrating gravity-driven compaction and vibration as in real casting procedures. This modeling approach is further developed to capture coupled mass transfer and electrochemical corrosion of steel, enabling simulations of non-uniform corrosion along both the circumferential and longitudinal directions of steel. The considerable variation in corrosion morphology due to aggregate distribution demonstrates the necessity of using 3D mesoscale models to predict steel corrosion. Early-age cracks accelerate the diffusion of corrosive agents, intensifying the corrosion of steel. Increasing the crack width, depth, and length all contribute to a higher dissolution thickness of the steel. With the same crack size, longitudinal cracks result in a larger average dissolution thickness of the steel. In addition, the maximum dissolution thickness of the steel is highly correlated with the degree of pitting corrosion, and in most instances, transverse cracks lead to a higher degree of pitting, causing a greater maximum dissolution thickness.