Assessment of the depolarization of cathodically protected reinforced concrete

Abstract

Cathodic Protection of reinforced concrete is covered under BS EN ISO 12696. There are four criteria for protection stated in BS EN ISO 12696. They are based on gathering accurate instant off data between 0.1 and 1 s after switching off the power to the zone. Further interpretation is based on collecting data over time with the system switched off. These criteria are largely empirical in nature but have a proven track record. Collecting the instant off value with any degree of accuracy is critical to assessing the performance of a system in comparison to this standard. Unless the system has an adequate logging facility this is difficult to achieve. As systems age the logging becomes less reliable, and software and hardware updates mean accessing it can prove problematic. This article reviews depolarization data from 261 reference electrodes installed at three sites. The anode systems include conductive coating anode systems, mesh and overlay anode systems and discrete anode systems. The paper comments on the forms of curves obtained and the protection criteria. It suggests a simpler method of assessing decay curves that can be readily achieved using manual logging.