Synergistic Effects of Plastic Deformation and Chloride Ions on Corrosion Initiation of Steel Rebars in Simulated Concrete Pore Solution

Abstract

The synergistic effects of plastic deformation and Cl− on corrosion initiation of steel rebars was examined by applying rapid tensile strain and cyclic stress to the steel in a simulated concrete pore solution with various concentrations of Cl−. In a rapid straining electrode test, the passive film of the steel was broken under plastic deformation and the anodic current increased sharply with the onset of slip step formation, whereas it was hardly broken under elastic deformation. Localized corrosion was initiated on the slip steps when the Cl− to OH− concentration ratio ([Cl−]/[OH−]) of the test solution was 0.4 or more. Localized corrosion also occurred under cyclic stress at [Cl−]/[OH−] ≥ 0.4. Experimental results demonstrated that the combination of slip step formation due to local stress concentration and the inhibition of repassivation by Cl− initiated corrosion under a significantly small [Cl−]/[OH−] ratio.