Laboratory Evaluation of Sacrificial Anode Materials for Cathodic Protection of Reinforced Concrete Bridges

Laboratory evaluations were conducted on a series of anode materials that could be used for sacrificial cathodic protection (CP) of reinforced concrete bridge decks. These included Al, Mg, and Zn alloys. Anodes were fabricated into test coupons and coupled to small lengths of reinforcing steel. The anode-steel couples were placed in simulated concrete environments consisting of sealed containers filled with silica sand treated with a mixed alkali solution containing 6 kg/m3 (10 lbs/yd3) of chloride ion (Cl–) by volume of sand. The treated sands were dried to obtain resistivities of 23 Ω-m, 100 Ω-m, and 260 Ω-m. Measurements of current flow, circuit resistance, potential, and depolarization were made over 18 weeks. Al and Zn anodes showed the most promise for use as galvanic anodes in reinforced concrete bridge decks.