Experimental study on shear-peeling bond strength between a CFRP plate and concrete

Diagonal tension cracks in reinforced concrete members adversely affect the performance of flexural members strengthened by externally bonded fibre-reinforced polymer (FRP) materials. The interface between FRP materials and concrete is influenced by both shear and peeling for such conditions. The objective of this study is to understand bond behaviour in carbon FRP plates and concrete systems under a combination of fracture modes (peeling and shear) by double-lap shear bond tests. The specimens were designed for different initial angles at the middle of the specimen to ensure that the interface acts for both shear and peeling conditions. From the test results, the bond behaviour under the combination of fracture modes can be observed by their strain distribution and load–displacement relation. The results also confirm that the tensile load decreases as the peeling angle increases. Moreover, a new calculation method to predict the bond strength between carbon FRP plates and concrete under shear-peeling fracture is proposed and agrees well with the test results.