Repair of Epoxy-Coated Reinforcement

Coating damage to epoxy-coated rebars (ECR) in chloride-contaminated concrete may lead to failure of the coating protection system. Damage to epoxy coating can occur during the stages of coating application, handling, storage, transportation, fabrication, assemblage, and/or concrete placement. Epoxy patching materials are manufactured to repair coating damage. In earlier corrosion studies at the University of Texas at Austin, performance of patched damaged areas in chloride contaminated concrete specimens and in ECR samples submersed in NaCl solution was marginal. [Report 1265-1, Kahhaleh] Patching delayed but did not prevent the onset of corrosion. Existing ECR specifications do not adequately describe proper repair procedures with patching materials. No systematic study of the efficacy of patching materials and repair procedures has been reported. In this research, performance of several patching materials was investigated. The effect of different bar surface conditions on the adhesion quality and corrosion performance of patching materials was examined. The effectiveness of patching rebar cut ends was of particular interest. Three major series of experiments were conducted: a) cyclic immersion in NaCl solution, b) electrochemical impedance and polarization resistance, and c) hot water immersion-adhesion tests. In cyclic immersion and electrochemical tests, the corrosion performance of repair materials was studied. In the hot water test, the adhesion quality of patching materials was examined.