Functionality of Zinc Anodes in Repaired Concrete

Zinc anodes are an effective and economical method to prevent and control the corrosion of steel bars. They supply the bars with cathodic current, which can provide corrosion protection at low current densities in the range of 0.2 to 2 mA/m2. The efficacy of zinc anodes is affected by the resistivity of concrete or cementitious repair material in which these anodes are embedded. Limited data is available on the maximum electrical resistivity of repair materials/concretes beyond which zinc anodes cannot properly function to prevent corrosion. In this study, concrete slabs were cast to simulate partial-and full-depth repair configurations. Key variables included resistivity and anode position. Resistivity of the repair section varied from 10,000 to 50,000 Ω-cm, with three anode positions: 25, 100, and 250 mm in the repair section. Analysis of data shows the effectiveness of anodes at controlling corrosion, even in repair concrete with high resistivity.