Cracking effects on chloride diffusion and corrosion initiation in RC structures via finite element simulation

Abstract

Chloride ion ingress into concrete causes steel corrosion over time, thereby ending the service life of structures. Sometimes, it severely reduces the loading capacity of reinforced concrete and may even cause the sudden destruction of concrete structures. Concrete cracking stems from different factors, such as shrinkage and tensile stress due to thermal loading and under loading. Modeling and estimating chloride ion ingress into cracked concrete over different periods can facilitate the appropriate determination of structural lifetime and maintenance of reinforced concrete structures. Accordingly, this research investigated the effects of the width and depth of concrete cracks on the rate of chloride ion diffusion and rebar corrosion. To this end, different concrete specimens characterized by various cracking conditions were modeled in COMSOL multiphysics. Analytical results showed that the critical crack that reflected the highest extent of chloride ingress into a specific region at different times was not necessarily the defect with the largest thickness and depth. This finding highlights the importance of investigating crack behavior in the appropriate estimation of structural service life. Nevertheless, over time, considerably wide and deep cracks may ultimately be a reflection of the substantial rate of ingress.