A Discussion on Utilization of Zinc Anode Applied in Cross-section Repair of RC Member Damaged by Chloride Attack - Time-Lag Application of Different Zinc Anodes -

Abstract

This paper discusses the effectiveness of zinc anode cathodic protection applied to RC beam specimens severely damaged by chloride attack. Based on the experiment, that is, the zinc anode cathodic protection is applied to the 41-year-old RC beam specimens exposed to natural marine environments, suitable application method of zinc anode is discussed. In the experiment, repair was performed in three stages. In the first stage, polymer-modified mortar was cast to replace existing concrete in the middle tensile part with zinc anodes embedded in the repair mortar. After protective current became stable value, the anodes were disconnected from steel bars for a year defined as the second stage. During the one year of second stage, the steel bar in the repair area remained be passive state, without any sign of corrosion. As for the third stage, additional zinc anodes were installed in the existing concrete part in order to protect the steel in old chloride contaminated concrete. From one-year observation after the application of zinc anodes in old concrete part, it is confirmed that “time lag application” could stop the corrosion of steel bar in both parts.