Experimental studies on bond strength between GFRP rebar and concrete C15

Experimental studies were performed on 12 pull-out specimens to investigate the bond-slip characteristics,loading process,failure mode,failure mechanism,bond strength,and anchorage length of GFRP rebar in concrete C15.The result shows that the bond stress of GFRP rebar specimens fluctuates within a range of 3-4 MPa when it decreases to 8%?13% of its bond strength,however,the bond stress of normal steel rebar keeps invariable when it decreases to 20%?30% of its bond strength.The bond strength of GFRP rebar in concrete C15 is relatively low.Taking GFRP rebar with diameter 6.35 mm and 9.5 mm as examples,the corresponding bond strengths of GFRP rebar are 8% and 37% lower than those of normal steel rebar with similar diameters respectively.When the bond strength of GFRP rebar is reached,the slippage of GFPR rebar is 3?5 mm,but the value is 1?2 mm for the normal steel rebar.Finally,some suggestions for design about rational bond strength between GFRP rebar and concrete C15 and anchorage length of GFRP were made.