Functionality of Zinc Anodes in Repaired Concrete Structures

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Zinc anodes are an effective, yet economical, method to mitigate the deleterious effect of corrosion of steel rebars embedded in reinforced concrete (RC) structures. Using zinc anodes at any repaired patch in an RC element prevents the onset of steel corrosion within a surrounding area; however, patch accelerated corrosion of steel rebars is a critical phenomenon that may take place in the original concrete in the vicinity of repaired patches depending on a number of parameters. One of the key factors affecting the efficacy of zinc anodes is the resistivity of concrete or cementitious repair material in which these anodes are embedded. However, no robust data are available on the maximum allowable electrical resistivity of repair materials/concretes beyond which zinc anodes cannot prevent corrosion of steel. In response to this issue, Vector Corrosion Technologies Ltd. has been pursuing opportunities to conduct a systematic research study to maximize the efficiency of zinc anodes at protecting RC structures from the risk of corrosion. Hence, the specific objective of this proposal is to explore the effect of concrete resistivity on the efficiency of zinc anodes at mitigating patch accelerated corrosion. Tests will be done on slab prototypes simulating this scenario, while varying the electrical resistivity of the repair concrete in combination with different anode spacing from the bond line with the original concrete. The corrosion activity of rebars will be monitored with time. This study will provide crucial information on the functional range of resistivity of repair materials/concretes and anode spacing, which will optimize the efficiency of an economical technology (zinc anodes) at protecting embedded reinforcement from the risk of corrosion. Over the long-term of this research, practical outcomes can be incorporated in repair guidelines for RC structures. Success of this research will offer a strategic solution for restoring, maintaining and improving vital infrastructural facilities (e.g. transportation infrastructure) required for sustaining the economic growth and quality of life in Canada.