Effect of cathodic protection of ordinary reinforcement on post-tensioned tendons: Case studies of post-tensioned bridges, Norway

Corrosion in ordinary steel-reinforced and prestressed concrete structures is a global challenge, particularly when exposed to chlorides from de-icing salts or seawater. While impressed current cathodic protection (ICCP) effectively mitigates corrosion in reinforced concrete structures, its application to ordinary reinforcement near post-tensioned tendons (especially damaged tendons) raises concerns about possible hydrogen embrittlement, which occurs when atomic hydrogen diffuses into high-strength steel, potentially compromising its ductility and load-bearing capacity. This risk necessitates continuous and careful monitoring of such ICCP systems during operation. The present study analyses the electrochemical conditions in zones containing post-tensioned tendons when ICCP is employed on the ordinary reinforcement to assess the possible impact on post-tensioned tendons. Several years of monitoring data from two Norwegian bridges were investigated, focusing on variations in applied voltage and current density, anode placement, polarization behaviour, and the effects on the prestressed tendons. Factors such as temperature fluctuations, humidity, and concrete resistivity, which influence the system, are discussed.