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Abstract Cathodic protection using galvanic anodes is a proven technique to control or prevent corrosion of steel in reinforced concrete structures. However, huge variations have been observed in the properties of various galvanic anodes available in the concrete repair market and their resulting performance. This work assessed the performance of five commercially available galvanic anodes using an earlier developed Galvanic Anode Performance (GAP) test. In addition, a methodology to estimate the guaranteed minimum service life (SLmin) of galvanic anodes in concrete systems exposed to specific environmental conditions is developed. This methodology involves the determination of electrochemical capacity (i.e., total electrical charge drawn) of galvanic anodes and the corrosion rate of galvanic anodes using potentiostatic scans. It was found that the average SLmin of the five anodes tested under severe laboratory exposure conditions (Relative humidity of 100% and temperature of 25 ± 2 ºC) ranged from about 3 months to 7 years – indicating huge variation in the quality of various galvanic anodes. The analysis of the physico-chemical characteristics of the encapsulating mortar of pristine and aged galvanic anodes showed that the average SLmin depends on the pH, activator content, total pore volume, and critical pore entry diameter of the encapsulating mortar and is irrespective of the mass of zinc. Also, the failure mechanisms of galvanic anodes observed during the GAP test are conceptualized and correlated to the properties of encapsulating mortar. Finally, a set of prescriptive and performance specifications for the selection of galvanic anode systems to achieve a target service life of repair is presented.
Manickam et al. (Fri,) studied this question.