| The key to improve the durability of concrete structures under harsh environments such as chloride and salt is to prevent steel corrosion.Epoxy coating is considered one of the most important methods to prevent steel corrosion.The traditional fusion bonded epoxy coating not only has problems in the product itself,but also has high energy consumption and pollution in the production process,which is not in line with the direction of green and sustainable development.Waterborne epoxy coating can overcome these shortcomings and achieve high corrosion resistance and green development of coated reinforcement by means of toughening and modification of epoxy resin and adding fillers.Based on the above understanding and existing work,this paper carried out the experimental research on the bonding performance between waterborne epoxy-coated steel reinforcing bars(WECR)and concrete,the performance of coated reinforced concrete,and numerical analysis.The main contents and conclusions are as follows:(1)The effects of key factors such as concrete strength,concrete cover thickness,reinforcement diameter,and anchorage length on the bonding behavior between WECR and concrete were analyzed by central pullout tests.The results showed that the ultimate bond strength of WECR to concrete decreased by about 10% and the peak slip increased by about 1 mm compared with that of ordinary reinforcement.(2)The reliability of the bonding anchorage between WECR and concrete was analyzed,and the critical anchorage length of WECR in concrete was calculated by the center point method.The results showed that the critical anchorage length of WECR was about 1.1 times that of ordinary steel reinforcement,which was recommended to be consistent with GB 50010-2010 and taken as 1.25 times in structural design.(3)The flexural performance tests of WECR concrete beams were carried out.The results showed that the load carrying capacity and deformation of WECR concrete beams were basically the same as those of ordinary reinforced concrete beams,but the average crack spacing and crack width were increased.Calculation of flexural load capacity of coated reinforced concrete beams can be carried out with reference to GB 50010-2010.(4)The finite element analysis of WECR and concrete pullout behavior was carried out,and the results showed that the coating slightly reduced the rib height and blunted the rib angle,which were the main reasons for the degradation in bonding performance.When the coating thickness is 400 μm,the relative bond strength between coated reinforcing steel and concrete is 85.9%.Therefore,in the preparation of the Chinese engineering construction standard for Waterborne epoxy coated steel reinforcing bars for concrete,it is proposed that the average thickness of the coating should not exceed 400 μm to meet the requirement of relative bond strength greater than 85%. |
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