Corrosion inhibitors in concrete repair systems

Corrosion of reinforcing steel represents the most widespread form of deterioration of concrete structures. It affects reinforced concrete which is exposed to the effects of carbonation and/or to significant concentrations of chloride salts. Effective procedures employed in the past to combat reinforcement corrosion have required either extensive cutting out and replacement of contaminated but otherwise sound concrete at the level of the embedded steel or the use of electrochemical measures such as impressed-current cathodic protection. Over the past decade, however, the concrete repair industry has developed novel techniques that are claimed to restore the protective character of cover concrete by introducing corrosion inhibitors into the carbonated and/or chloride-contaminated material. As this approach requries only physically unsound or heavily contaminated regions of the concrete to be removed and reinstated it can involve reduced costs, pollution and inconvenience to owners and users of affected structures. This paper presents a critical review of current knowledge of various types of corrosion inhibitor treatment that are in use, or under consideration for use, in repair systems for concrete structures with corrosion problems resulting from carbonation and/or chloride salts.