Experimental Study On Bond Behavior Of CFRP-concrete With Longitudinal Grooves

Fiber reinforced polymer(FRP)is a common method for strengthening concrete structures.When the sheet is reinforced only by sticking,it is easy to have brittle peeling failure along the interface prematurely,which is not conducive to the effective use of material strength and the safe service of the reinforced structure.The traditional process includes pre-gritting of concrete surface to enhance the bond property of FRP-concrete interface,but there is no quantitative standard for gritting quality evaluation at present.Surface grooving is convenient for mechanical operation and quality control,and the anti-stripping effect is better than chiseling under certain conditions.However,the relevant research is not systematic and in-depth.In this paper,the effects of different surface treatments,grooving width,depth and bonding surface on the normal and tangential bonding properties of the interface were systematically studied by tensile test and single shear test.The main work and research results are as follows:(1)Tensile bond test of CFRP sheet and grooved concrete was carried out for the first time.The test results of 30 specimens show that the positive tensile bond strength is slightly affected by the width of the groove,but increases linearly with the increase of the depth of the groove,and the increase is up to 33.3% compared with the non-grooved specimen.(2)The single shear tests of 22 CFRP cloth-grooved concrete specimens were completed.The bond properties of the specimens with only the side or bottom of the groove and the whole groove were studied respectively,and the mechanism of grooved bond stripping was revealed.It is found that when the grooving size is appropriate,the grooving bonding effect is better than that of gouging and grinding.The mean value of ultimate shear stress increases with the increase of groove width,and then decreases with the increase of groove depth.Compared with the specimen without groove paste,the maximum increase is 380.6%.When the adhesive area is the same,the adhesive force at the trough side contributes more to the ultimate shear force than that at the trough bottom.(3)Through the single shear test of end-anchored CFRP-grooved concrete interface bond performance,the ultimate tension and ductility of end-anchored CFRP-grooved concrete interface bond performance are improved by 425% and 350% respectively,which can realize effective prevention of interface peeling and make full use of material strength.The superiority of this technique is proved.(4)The Origin software was used to fit the test results of 3d nonlinear surface,and the bond strength model of CFRP-grooved concrete was proposed,which was in good agreement with the test results in this paper.