Discrete embedded zinc anodes have been proposed to extend the service life of concrete patch repair by providing localized cathodic protection to adjacent steel. The performance of such anodes must be enhanced by chemical agents, which maintain the zinc in an electrochemically active state and increase the flow of protective current to the steel. In this study, the effects of various chemical agents were studied by monitoring both the flow of current and steel polarization on laboratory test blocks. Protective current for test blocks containing zinc anodes and lithium-based activating agents at both 55% and 80% relative humidity can be ranked as follow:
LiBr > LiNO3 > LiOH.
Mixtures of LiBr and LiNO3 were also found to be very effective.
Potential decay tests have demonstrated that zinc anodes activated by the most effective agents are capable of polarizing reinforcing steel up to 100 mV, and are therefore likely to have a significant beneficial effect on the service life of concrete patch repair.
Keywords: anodes, cathodic protection, concrete, concrete patch repair, corrosion, lithium chemicals, reinforcing steel, zinc.