Effect of inhibitors and coatings on rebar corrosion

Chloride-induced corrosion of reinforcing steel is a major cause of deterioration of concrete structures in the eastern province of Saudi Arabia. Two of the practical ways of preventing or retarding corrosion of reinforcing steel bars in concrete are by using (a) inhibitor in concrete mix, and (b) coating either on the rebars or on external surfaces of concrete structures. The objective of this study has been to evaluate the effect of two inhibitors, three concrete coatings, and two barrier coatings on corrosion of reinforcing steel bars. Reinforced concrete specimens were monitored by AC and DC electrochemical techniques while undergoing free and accelerated corrosion. Accelerated corrosion tests were performed under 4V impressed anodic potential. Corrosion of the steel bars were evaluated by measuring anodic current, time-to-cracking of concrete specimens, and corrosion rates of the steel bars. The results showed that the specimens with the concrete surface coatings did not perform better than the control specimens. Time-to-cracking was shorter and corrosion rate of steel bars was higher in specimens coated with concrete coatings. The inhibitors and rebar surface coatings reduced the corrosion rate of steel bars significantly and improvement the time-to-cracking of the specimens in comparison to control specimens.