Due to the shortage of fresh water and river sand in coastal areas, seawater, and marine sand sometimes must be used in the preparation of concrete for construction. Thus, the corrosion of steel rebar in seawater and marine sand concrete cannot be ignored. In this study, the feasibility of using HRB400 steel in seawater and marine sand concrete was determined based on steel rebar corrosion. Electrochemical methods were used to investigate the passivation and depassivation of HRB400 steel in curing and inservice concrete, respectively, and to determine conditions for forming a stable passive film and the critical chloride threshold for the steel depassivation. Our experimental results demonstrate that HRB400 steel cannot be directly applied in seawater concrete but may be used in marine sand concrete when the concentration of mixed-in chloride is no more than 0.05 M because low concentrations of mixed-in chloride had no effect on the properties of the passive film. K E Y W O R D S critical chloride threshold, HRB400 steel, passivation behavior, seawater and marine sand concrete 1478 |