Experimental study on the interfacial bond behavior of FRP plate-high-strength concrete under seawater immersion

•A new type of grooved GFRP shear key was studied and applied.•High-strength concrete was applied to investigate the durability of GFRP plate-concrete interfaces.•The durability of four types of GFRP plate-high-strength concrete interfaces was compared.•The bond behaviour of the four types of interfaces were studied. The excellent bonding performance of the glass fiber-reinforced polymer (GFRP) profile-high-strength concrete interface is the key to ensuring the safety, reliability and durability of a composite structure. Therefore, it is necessary to study the durability of the composite interface. In this paper, a total of 48 GFRP plate-high-strength concrete double-lap joints were tested to investigate the effect of the epoxy resin type, interfacial type and artificial seawater immersion time on the bonded interfaces. The main properties of the bonded joints were examined, including the failure mode, ultimate load, load-slip curve, typical strain and shear stress distributions along GFRP plates. The results showed that the ultimate loads of each type of interface gradually decreased with increasing immersion time. After 360 days of artificial seawater immersion at a constant temperature, the ultimate load of the wet bond (WB) interface had the largest reduction, and the ultimate load of the dry bond (DB) interface showed a minimal decrease. The ultimate load of the shear key combined with wet bond (SK-WB) interface was significantly greater than that of the other three interfaces under different immersion ages. In general, the durability of the interface with the CFSR type (B-type) epoxy resin was superior to that of the Sanyu L-500 type (A-type) epoxy resin. The strain and interfacial shear stress distributions along GFRP plates of the DB interface specimens were different from that of the SK-WB interface specimens under different immersion ages.