What is Chloride Attack in concrete?

Chloride attack occurs when chloride ions (from seawater, sea spray, or de-icing salts) penetrate the concrete cover and reach the steel reinforcement. Unlike carbonation, chlorides do not lower the pH but directly attack the passive layer on the steel, causing localized 'pitting' corrosion. This type of corrosion is dangerous because it can significantly reduce the cross-sectional area of the rebar without showing obvious surface signs until severe damage has occurred. We treat this by removing contaminated concrete or using electrochemical extraction.