Corrosion risk of reinforced concrete structures following three years of interrupted cathodic protection

Impressed Current Cathodic Protection (ICCP) has contributed significantly to the repair and maintenance of motorway structures in the U.K. By polarising the steel reinforcement it can arrest and prevent corrosion activity and can take away the necessity to remove chloride contaminated but otherwise sound concrete. The aim of this research was to collect data from full-scale motorway reinforced concrete structures which had ICCP systems applied for a range of years and to assess their performance with regards to corrosion. It was found that for structures which had received a protective current for 5 years or more, the steel reinforcement retained a residual passive corrosion condition for at least 3 years following interruption of the protective current. This was despite the fact that in several structures the residual corrosion risk was high, based on the concentration of chlorides that was found at the depth of the reinforcement. It can be concluded that the application of ICCP on reinforced concrete structures for more than 5 years transforms the steel-concrete interface.