Investigation on efficiency of cathodic protection applied on steel in concrete cylinder with CFRP wrap serving as anode

Abstract

The combination of strengthening and corrosion protection by using multi-functional material is an attractive topic recently. In this paper, carbon fiber reinforced polymer (CFRP) was utilized as a repair material and an anode of impressed current cathodic protection (ICCP) owing to its excellent mechanical and electrochemical properties. The effects of protection methods (non-protection, epoxy coating, CFRP wrapping, CFRP wrapping and ICCP), pre-corrosion degrees (3 %, 6 %, and 12 %), and ICCP current densities (5, 20, and 80 mA/m2) on corrosion performance of reinforced concrete (RC) cylinders were investigated by means of electrochemical measurements. The results showed that the double protection provided by CFRP wrapping and ICCP worked much better than the sole epoxy coating or the sole CFRP wrapping when an appropriate current density was applied. The optimal ICCP current density depended on the pre-corrosion severity of RC specimen. A current density of 20 mA/m2 resulted in the greatest improvements in charge transfer resistance for the 6 % and 12 % pre-corroded specimens while the optimal current density was 5 mA/m2 for the 3 % pre-corroded specimen. Moreover, CFRP wrapping led to greater increases in charge transfer resistance than epoxy coating. It suggested that, besides the contribution of epoxy to isolate harmful substances, confinement provided by CFRP wrapping may benefit corrosion alleviation in a further step by densifying the core concrete and consequently impeding ion transport and oxygen availability. This work provides a basis for further optimization design of ICCP-strengthening technique applied on corroded RC components to achieve higher efficiency.