Durability Of The Bond Performances Of FRP-to-concrete Under The Corrosive Environment Of High Temperature And Dry-wet Cycling

Scholars and engineers have paid more and more attention on the FRPreinforced concrete technology. FRP reinforced concrete structure is usuallyexposed to the outside. Under the influence of corrosive environment, someproblems will also restrict the development and promotion of the technology ofFRP reinforced concrete, such as the structure’s durability and how to design thedurability of FRP reinforcement components. From the study of the degradationof materials (FRP, resin, concrete) to the interface bonding (performance ofFRP-to-resin and FRP-to-concrete), this paper has systematically analyzed thebond performances of FRP-to-concrete under the corrosive environment of hightemperature and dry-wet cycling. Main research results of this thesis are asfollows.The study on the durability of materials is the basis of the research ondurability of interface. Based on the mechanics and micro experiments, thispaper has studied the influence of the environment of high temperature anddry-wet cycling on the degradation of the tensile properties of carbon fiber, glassfiber and resin and the compressive strength of concrete. The results showed thatin300times of the action of high temperature and dry-wet cycling, the tensilestrength of CFRP didn’t go down, and elongation at break declined slightly.Compared to CFRP, the tensile strength and elongation at break of GFRPdeclined much more, and the elastic modulus of two kinds of FRP remained to beunchanged; the results of macroscopic and microscopic experiment showed thatthe post curing in the dry-wet circulation has a great influence on the mechanicalproperties of the resin in early phase. The compressive strength of concrete isbasically no change.The good bond performance between FRP and the resin is one of theprecondition to the overall performance of FRP-concrete structure. This thesishas studied the degradation of the bond performances of FRP-resin through themacroscopic and microscopic experiment of60FRP lap joint specimens underdifferent times of high temperature and dry-wet cycling. The results showed thatthe interface bond properties of FRP-resin are unchanged in the environment during the300cycles. Using more resin and selecting the right FRP with roughsurface and big cellosilk gap can effectively improve the interface durability ofFRP-resin.The interface bond properties of FRP-concrete directly affects the overallperformance of FRP-concrete structure. This thesis has studied the degradationof the interface of FRP-concrete through the single shear test of theFRP-concrete specimen under the corrosive environment of high temperature anddry-wet cycling. Through the existing model of the interface bond strength, therelevant parameters was found which influence the interface bonding strength.The results showed that after300cycles, the bearing capacity of CFRP-concreteinterface felled by9%, the bearing capacity of GFRP-concrete most by23%;under the corrosive environment of high temperature and dry-wet cycling, thedegradation of the interface bonding performance was mainly affected by thedegradation of the resin. The durability of CFRP-concrete structure is better thanthat of GFRP-concrete structure. In this environment, we can ignore theinfluence of the concrete changes on the degradation of the bond performances.