Electrochemical Potential Monitoring of Corrosion and Coating Protection of Mild Steel Reinforcement in Concrete

The corrosion and protection behavior of a mild steel reinforcement in concrete, partially immersed in different test media, was investigated at ambient temperature by potential monitoring technique. The work was carried out using a digital voltmeter and a copper sulfate electrode (CSE) as the reference electrode. The obtained results showed that corrosion occurred on the embedded steel by the processes of anodic and cathodic reactions. The active corrosion of the steel occurred by the depassivation of the hydroxyl ions stablized passive film on the steel's surface and the consequent anodic dissolution of the reinforcement bars. The corrosion of the embedded steel was enhanced by the diffusion of chloride, sulfate, and carbonate ions from the test media, in addition to the absorbed oxygen and water/moisture. The coating of the reinforcement steel with, paint before embedding in concrete block gave some measure of protection. Coating of the concrete blocks externally was a more protective method. However, a combination of the steel coating and external coating of the concrete block showed the most effective corrosion protection comparatively.