Effect of Stress on the Critical Chloride Content of Steel Bar in Simulated Concrete Pore Solution

This work reveals influence of the stress state of steel bars on the critical chloride content for depassivation in a simulated concrete pore solution (SCPS). The passivation behavior of steel in chloride-free SCPS and depassivation behavior in SCPS with incremental addition of chloride were studied by electrochemical techniques including electrochemical impedance spectroscopy, Mott-Shottky test, cyclic voltammetry, and others. Results demonstrated that stress enhanced the redox activity in highly alkaline SCPS, where enhancement by tension was more pronounced than compression. Additionally, stress increased the donor density and dielectric properties of the constant-phase element of the passive film. The critical chloride content of steels can be considerably lowered by 80% under stress.