Investigation of electrochemical chloride removal from concrete using direct and pulse current

Abstract

Electrochemical chloride removal (ECR) technique as an effective repair method has been applied to chloride-attacked concrete structures. This research studies the influence of different external electrical fields on the ECR treatment for reinforced concrete. Two types of electrical fields including direct and pulse current with average current densities of 2, 3 and 4 A/m2 were investigated. The chloride ion content of concrete before and after ECR treatment was determined. The results show that no matter what current density was used for concrete repair, the effect of pulse current on the desalination of concrete was better than direct current. Also, increasing the current density can also promote the concrete chloride removal efficiency. When applying a current density of 4 A/m2 to the steel rebars for 28 days, the remained chloride concentration of the concrete after ECR treatment was obviously lower than that of using 2 and 3 A/m2. In addition, the half-cell potential method was used to evaluate the rebar potential distribution. It was found that the pulse current can make the cathode reinforcement arranged in parallel in the concrete have a more uniform potential distribution, which indicates that the applied electrical current is easier to uniformly pass through the whole concrete structures.