Maintenance of structural integrity using cathodic protection

Cathodic protection has been applied to reinforced concrete structures in the UK as a reinforcement corrosion protection technique since the 1980s. It is now well established in the toolbox of repair techniques available for chloride-contaminated reinforced concrete structures. Cathodic protection is an 'active' technique and includes an ongoing operation and performance-monitoring commitment. The technique works by introducing an anode through which a small direct current is applied to protect the reinforcement. Monitoring is required to ensure that the current is maintained at the correct level to maintain the reinforcement adequately. This paper provides a brief history of the use of cathodic protection on reinforced concrete in the UK, including the trials and subsequent wholesale use of the technique on the Midland Links motorway viaducts. Also described are the operating and performance-monitoring requirements for cathodic protection systems, including the sensors and monitoring and control equipment used. The paper also discusses the use of monitoring data in the management of cathodic protection systems, and the structures to which they are applied, to predict future performance and life, allowing future maintenance interventions to be planned and providing best value for structure owners.