A comparative investigation on cathodic protections of three sacrificial anodes on chloride-contaminated reinforced concrete

Abstract

This paper aims to evaluate the cathodic protections of zinc alloy, magnesium alloy and aluminum alloy as sacrificial anodes on chloride-contaminated reinforced concrete by a comparative experiment. For simulating the real condition, the large concrete slab with steel-mesh (size: 1.0 m × 1.0 m × 0.06 m) was fabricated. The measurements of half-cell potentials, anode stimulation current, electrochemical impedance spectroscopy (EIS) and the titration analyses of chloride irons contents in the concrete slabs at different times were carried out. The results indicate that the aluminum alloy anode cannot provide enough cathodic protection to the steel due to the loss of activity in the long term. Both zinc alloy and magnesium alloy have a good electrochemical activity and stability as a sacrificial anode. In comparison with zinc alloy, the magnesium alloy anode has the better ability of cathodic protection on the reinforcing steel. The cathodic protection effects for three anodes can be verified by the shift of characteristic frequency corresponding to the maximum value of the phase angle in the Bode plot of EIS. The chloride migration contributes to the effect of cathodic protection.