CATHODIC PROTECTION OF REINFORCING STEEL

An account is given of the use of cathodic protection in controlling the corrosion of reinforcing steel. A technique which has been widely used in the USA and Canada, it is applied particularly to concrete bridge decks. The way in which corrosion develops is described together with contributing factors such as constructional defects or physical and chemical degradation. Difficulties encountered by the cathodic protection engineer are outlined and include the limited throw of protective current through the poorly conducting concrete and the physical restraints to anode groundbed installation imposed by the design of the bridge structure. The greatest difficulty is identified as monitoring the effectiveness of cathode protection and it is suggested that rather than as an established option for dealing with corrosion the technique should be viewed as an experimental procedure worthy of further study. This study was carried out by Spencer and Partners on behalf of the Transport & Road Research Laboratory. (TRRL)