Electrochemical Behavior of Steel in Salt Contaminated Concrete: Part 1

Corrosion of steel in concrete is a problem because of the presence of chloride ions at the metal-concrete interface. The chloride ion is introduced as a contaminant in the mix or from the sources such as deicing salt or seawater. The electrochemistry of steel in this system is not well defined. This paper presents the polarization curves for steel in Type I and V portland cement with various salt contents. The degree of corrosiveness of steel in these two portland cement concretes was evaluated. Laboratory-dry and water-saturated concrete samples were used to determine the electrochemical behavior of steel at the presence of chloride ions in these conditions. The anodic polarization curves indicated that the steel passivates in the concrete sample of Type I portland cement with the salt content up to 0.1 %, but the passivity of steel was maintained up to 0.5% in Type V portland cement. (The samples had been exposed to distilled water for 90 days after removal from a water cabinet). The anodic polarization curves indicated no passivity for the samples exposed to the dry condition of the laboratory.