Experimental Research On Durability Of Bond Performances Of FRP-Concrete Under Wet Hot Environment

With the wide application of strengthening technique of FRP in civil engineering, the durability of the technique is becoming the focus of the researchers. As time of the application of FRP in structural strengthening is short and structural strengthening in real engineering application is in out doors or other rugged environment, the weakness of FRP concrete structural strengthening often appears on the bonding surface between FRP and concrete. Therefore, durability research of the bonding surface between FRP and concrete in this kind of environment is necessary. The durability of the bonding surface between FRP and concrete in wet-dry environment and natural environment from the angles of material and bonding surface was studied in this test.The change rule of CFRP, BFRP and resin test specimen in wet-dry environment and natural environment was studied in this test. The test result indicated:tensile strength and limiting strain of CFRP in wet-dry environment and natural environment declined slightly, modulus of elasticity changed little; mechanical property of BFRP decayed very fast; environment made great influence on mechanical property of resin, tensile strength and limiting strain of resin descended fast and tend to be stable in the later stage, but the decline range of modulus of elasticity was little; environment made a little influence on the compression strength.The bonding surface between FRP and concrete in wet-dry environment and natural environment through the experiment of 126 FRP-concrete specimens was analysed in this test. The test result indicated:the commonest destruction form were peeling failure and shear peel mixed failure; with time going on, ultimate bearing capacity descended, curve of strain and shear moved backward, indicating that both wet and dry cycle and natural exposure environment had adverse effects on the test specimens; deflection of the specimen through wet and dry cycles action after a slight decline, but was not affected by exposure to the natural environment; durability of CFRP reinforcement structure was better than that of BFRP in wet-dry environment and natural environment.