Abstract: In order to improve the bonding performance between CFRP (Carbon fiber reinforced polymer) and concrete, resin pre-coating technique (RPC) was used to pretreat the concrete surface, and short chopped Kevlar fibers were used to reinforce the resin layer. The interfacial bond behavior between CFRP and concrete was then analyzed by the single-lap shear test. Firstly, the effect of RPC technique was evaluated for the specimens with the same bond length. The optimal fiber content was determined upon the comparisons between the maximum bond loads with different fiber contents. Secondly, based on the optimal fiber content, the effects of different bond lengths on the bond properties with different interfacial treatments were analyzed. The results show that the optimal fiber content is 9 g/m². For the specimens with different bond lengths, the maximum bond load with RPC technique is increased by 12.7%~142.9% compared to the specimens without any interfacial treatment. Moreover, the failure mode of the reinforced interface is mainly the shear failure of the adhesive layer accompanied by few peeled concrete layers. RPC technique can fill the micro cracks in the concrete surface, and then the failure mode of peeled concrete layer with deep depth can be avoided. The bridging effect provided by the random distributed fibers strengthens the resin layer, and inhibits the development of cracks. Thus, the bond strength is improved significantly.

Key words: Kevlar fiber, CFRP, resin pre-coating, interfacial reinforcement