Investigation of bond behavior between waterborne epoxy-coated steel reinforcing bars (WECR) and concrete

Understanding the bond behavior of waterborne epoxy-coated steel reinforcing bars (WECR) and concrete is a prerequisite for its application in concrete structures. In this study, a total of fortyeight pull-out specimens were tested to investigate bond behavior between WECR and concrete. The failure modes and bond stress-slip relationships were analyzed and discussed in detail. The formula for the ultimate bond stress between WECR and concrete was obtained. The critical anchorage length of WECR was calculated by reliability analysis. Finally, the detailed 3D finite element model was established to simulate the effect of coating thickness on bonding behavior. The results showed that, compared with ordinary reinforcement, the ultimate bond stress between WECR and concrete decreased by about 10% and the slip increased by about 1 mm. The critical anchorage length of WECR was about 1.1 times that of ordinary reinforcement, and it was recommended to take 1.25 times in the structural design. The change in rib height and rib angle due to coating is the main reason that affects the bonding performance.