Limitations and advantages of electrochemical chloride removal in corroded reinforced concrete structures

Existing experience on electrochemical methods for the rehabilitation of corroded reinforced concrete structures (RCS) shows that chlorides can be removed from these structures and that carbonated concrete can be realkalised. However, the current state of know-how has not advanced sufficiently to dissipate serious doubts about the efficiency of electrochemical chloride removal (ECR) and electrochemical realkalisation (ERA). A fundamental controversy remains to be resolved, which can be summarised in the following question: Once the causes of corrosion have been removed, does the corrosion of corroded RCS cease? The present work attempts to find an experimental response to this question, determining the corrosion rates of corroded rebars embedded in cement mortar slabs with chloride additions, before and after the application of ECR, and of clean and prerusted steel electrodes embedded in small chloride-free mortar specimens. According to the results obtained, if ECR is applied preventively it is an efficient procedure for delaying the start of corrosion. However, if applied too late it does not assure the repassivation of corroded RCS and is therefore useless. (c) 2007 Elsevier Ltd. All rights reserved.