Effectiveness evaluation of electro-chemical chloride extraction in reinforced concrete

Abstract

Rehabilitating the reinforced concrete structure contaminated with chloride from the marine environment was always interesting research. Electrochemical chloride extraction (ECE) is one of beneficial options. However, the feasibility and effectiveness of it is still on arguing, especially in concrete using mineral admixtures and concrete satisfied the requirement for using in marine environment according to ACI 318 which has low water to binder ratio. In this study, ECE was applied in plain OPC concrete, fly ash concrete with 30% of fly ash by weight of binder, limestone fly ash concrete with 25% fly ash and 5% limestone powder by weight of binder, respectively. Water/binder ratio was 0.4, minimum strength 35MPa. Two percentage of sodium chloride by weight of binder was added in mixing water to supply chloride. The results indicated that, all three types of concrete showed that, after extracting 30-40% of initial chloride content in concrete, even thought average remained chloride in concrete was still higher than critical value of chloride in concrete, embedded steel in concrete was shown the delete low corrosion risk stage. Moreover, it also indicated that the contribution of calcium ion on the current flow during extracting process electrical current on extracting process was insignificant; meanwhile, hydroxyl, sulfate, chloride, sodium and potassium played the main role on transferring the charge.