Corrosion initiation time prediction considering influences of cross-section shape and obstruction of reinforcement bars

Chloride-induced corrosion of reinforcing steel can cause the performance deterioration of reinforced concrete structures in marine environment. In this paper, the Fick's second law is used to describe the free chloride concentration evolution in concrete considering the effect factors of chloride diffusion coefficient and chloride binding isotherms caused by cementitious materials. The effects of cross-section shape and obstruction on corrosion initiation time were discussed thoroughly. The corrosion initiation time can be prolonged for some chlorides bound by physical and chemical adsorption. The free chloride concentration at corner of square cross-section is much larger because it is influenced by chlorides from two directions. The corrosion initiation of reinforcing steel at corner becomes shorter and the longitudinal cracks along bars arise early. The influence on corrosion initiation of reinforcing steel is significant in circular cross-section, especially when concrete cover is thicker or boundary chloride concentration is lower. Free chloride concentrations increase at the frontier of rebar considering the obstruction of rebar. The obstruction gives much influence on corrosion initiation, especially when concrete cover is thinner or boundary chloride concentration is lower.