Experimental Investigation of Fundamental Bond Mechanisms of GFRP Rebar with Various Surface Patterns

In this study, the fundamental bond mechanisms of various surface type for GFRP rebars were mentioned in terms of pullout force vs. relative slips of loaded and free end. The ribbed, braided and covered type of GFRP rebar were used for experimental program. The effect of surface deformations on bond mechanisms was investigated. For the ribbed type of GFRP rebar, the effect of an increment on amounts of milled glass fibers in ribs on bond mechanisms was also investigated. The results demonstrated that for ribbed and braided type of GFRP rebars the bearing resistance and frictional resistance of surface deformation dominated bond performance with concrete, respectively. Moreover, for covered type of GFRP rebar the bond was significantly affected by the adhesive between the core and surface covered layer. In addition, the bearing resistance of the ribbed type of GFRP rebar could be marginally improved by increasing amounts of milled glass fibers in ribs.