The selection and use of cathodic protection systems for the repair of reinforced concrete structures

Cathodic protection (CP) is an electrochemical repair technique that has increasingly been used for the repair of reinforced concrete structures in the UK and worldwide. Cathodic protection generally works by the passing of a small electrical current from the anode to the corroding steel reinforcement thereby protecting it from further deterioration by increasing the hydroxyl ions locally. This paper has looked at the advantages and disadvantages of using the two types of cathodic protection systems, namely sacrificial anode and impressed current CP, and highlighted some of the design considerations and challenges faced on a number of case histories that Mouchel have undertaken. From our experience the decision whether to use an impressed current CP system or a sacrificial anode CP system is influenced by a number of factors including but not limited to the condition (the level and extent of deterioration) of the structure, the client’s budget and the anticipated life expectancy of the structure following the repairs. Experience at Mouchel indicates that the circumstances where SACP is most suitable includes small and targeted repairs, repairs where budget costs are limited and repairs where the life expectancy is anticipated to be around 10 years. On the other hand, ICCP is generally used to address significant corrosion problems to large structures and surface areas, where life expectancy is expected to be more than 25 years and where access and traffic management are challenging and very costly.

► Various design considerations and challenges are encountered in the use of cathodic protection.
► CP is an accepted long term repair method for corrosion of reinforcement in concrete structures.
► Main factors influencing the use CP are condition of structure, client’s budget and life expectancy.
► SACP is most suitable on targeted repairs with limited budget and life expectancy of around 10 years.
► ICCP is used on large structures with significant corrosion and life expectancy of around ⩾25 years.