An assessment on the mill scale effects on the electrochemical characteristics of steel bars in concrete under DC-polarization

The effects of mill scale on formation and stability of passive film on rebars in chloride-bearing concrete is investigated. Studies were carried out on some electrochemical parameters such as repassivation potential, Erep, and passive current density, ipass, using cyclic potentiodynamic polarization. The superficial mill scale on the rebars was naturally produced during hot-working of steel. The experiments were performed in the concrete samples with a cement/sand/water ratio 1:3:0.6. The results demonstrated that the presence of mill scale on the rebars in chloride-free concrete causes a decrease in electrical resistance of the passive film and its reparability. However in presence of chloride ions because of the severity of corrosion the effect of mill scale on corrosion of rebars is less manifested.