Mobility of Chloride in Concrete Subjected to Electrochemical Treatment

Abstract

In this study, chloride mobility after electrochemical treatment in concrete was evaluated. Once a concrete specimen containing three steel reinforcing bars was exposed to 4M NaCl for 365 days, electrochemical chloride extraction was applied to the reinforcing bars for 8 weeks at 750 mA/m2 (0.484 mA/in.2 ) direct current. To evaluate chloride mobility, chloride concentration at all depths was measured for total, free, and bound ones by chloride profiling. Simultaneously, the corrosion rate and potential were measured during the treatment. The removal efficiency for total chloride was significant, ranging from 26.2 to 70.2% compared to the untreated specimen. Free chlorides were mostly removed from the concrete body except for the nearer surface, and bound chloride concentration was surprisingly reduced to 0.67 to 0.74%, irrespective of the depth. Moreover, the corrosion rate and potential indicated that the risk of corrosion was mitigated. A visual examination for steel reinforcing bars confirmed that rust was dramatically reduced after the treatment.