Impressed current cathodic protection with embedded anodes – field trial on the Viaduc de Saint-Cloud in France

This paper deals with the electrochemical repair of a road bridge, Viaduc de Saint-Cloud which was constructed in the 1970's in France. In 2011, a corrosion analysis was performed together with a durability study. It was demonstrated that the corrosion was induced by chloride ions coming from de-icing salts leaking from the deck. The induced corrosion was increased by the low cover depths resulting in a chloride penetration beyond the reinforcement depth. In order to evaluate the effectiveness and the reliability of Impressed Current Cathodic Protection (ICCP) with embedded anodes, a field trial was performed in 2012 on three span segments including one segment over pier (P2). The results of the ICCP design, the implementation and the monitoring are presented. It was found that two months were necessary before the cathodic protection would reach an equilibrium. Performance criteria as described in ISO 12696 dealing with cathodic protection passed on two segments but failed on the segment over pier. On the latter, where the congestion of reinforcement and prestressed tendons was higher, the anodic system needed some improvement. Finally, the results of the field trial allowed proposing a technical and an economic repair solution.