A study of the bond degradation of rebar due to catholic protection current

Bond degradation of rebar embedded in concrete due to impressed catholic protection current was studied and is reported in this paper. Different mix designs of concrete are found to have influence on the degradation percentage of bond strength. More specifically, bond strength degradation percentage with higher water-to-cement (w/c) ratio is found to be larger than that with lower w/c ratio. The microstructure scanning electron microscope (SEM) photos of the concrete near the rebar-concrete interface showed that a loose structure with larger microvoids existed in the interface zone. Further, microhardness tests on the concrete near the interface and chemical titration to determine contents of potassium and sodium ions were performed to ensure that the main cause of bond degradation is the softening effect of concrete. A unified parameter, which combined the effects of catholic current density and polarization time, is used to build up the relationship between experimental data. This concept allows engineers to quickly obtain design information from the experimental data of accelerated tests. (C) 2002 Elsevier Science Ltd. All rights reserved.