Experimental Study On Tensile Mechanical Properties, Durability And Adhesion To Concrete Of FRP-steel Composite Ribs

In modern industry and construction,reinforced concrete is a kind of structural material occupies a large proportion.When exposed to adverse environment(Carbonation,Chlorine Ion Corrosion,Marine Environment,etc.),the rebar frame of the reinforced concrete is more vulnerable to corrode affected by the harmful medium,so the life of the concrete structure will be shorten.FRP is a popular material in recent years not easy to corrode.However,FRP is a fully linear elastic material without sufficient ductility,so it is difficult to be prompted to industrial application.Therefore,in this paper,a new kind of composite rebar combines the advantages of the two materials is proposed,which wrapping fiber material outside the steel rebar to form a FRP-steel composite rebar.Referring to the production process of the pure FRP rebar,this paper puts forward the forming process of FRP-steel composite rebar(hereinafter referred to as composite rebar).And using the equipment of FRP rebars,we has completed the industrial production of the composite rebar and the basic mechanical properties and durability of it were experimental studied.The main work is as follows:Through the experiment study on different types of composite rebars under tensile Impact,we could describe the failure modes and analyze the yield strength,ultimate strength,elastic modulus and stress-strain curve of the composite rebar.Based on the mixing rule of composite materials,we established a stress-strain constitutive model of the composite rebar and found it fitted with the experimental data very well.Through the accelerated corrosion test,we obtained specimens of composite rebar with different designed corrosion rates.Using scanning electron microscope(SEM)and energy dispersive spectroscopy(EDS)techniques,we took qualitative analysis on the specimens and found a few suspected rust products in there.Through the analysis of the rust layers distribution in different rebar and the pore structure of the coating fibers,we found that the fiber's type and its pore structure have significant influence on the corrosion resistance of the composite rebar.We also used the X-ray micro computed tomography(Micro-XCT)technology on subjects in the corrosion specimens to have a quantitative analysis and found the actual corrosion rate of the composite rebars were far less than round steel bars without fiber coat,the actual corrosion rate of CFRP-steel composite rebar is less than 1/10 of the steel's,the actual corrosion rate of GFRP-steel composite bar is less than 1/100.Thus it can be concluded that the composite rebars have better corrosion resistance.Based on the experiments on Bond Slippage Relation of composite rebar Concrete,we mainly analyzed the impacts on the failure mode of the composite rebar concrete specimens,bond strength and bond-slip curve imposed by the fiber species,the diameter of the rebar and the surface treatments.