Effect of Surface Texture on Bond Strength of GFRP Rebar in Concrete

GFRP (Glass Fiber Reinforced Polymer) rebars are frequently used as reinforcement for reinforced concrete. This concrete being a composite material resists the flexural & shear loads, if adequate bond exists between GFRP rebars and concrete & through which transfer of stresses take place between them. The bond strength of such concrete is a function of several factors. out of these factors, surface texture of GFRP rebars is one of the most important parameters. Experimental study was carried out with data acquisition system and linear displacement transducers to determine the effect of surface texture (sand coatings on GFRP rebars) on adhesion & frictional component of the bond strength. overall and post peak bond behavior was studied through pullout tests using strain controlled universal testing machine. The results of experimental work showed that by sand coating on GFRP rebars, bond strength increased for both large and small diameter rebars. Furthermore for smaller diameter rebars, the effect of sand coating was more pronounced as compared to medium & larger diameter rebars. The sand coating improved the friction between GFRP rebars and the surrounded concrete. moreover, after failure of chemical adhesion due to slip, friction between broken sand particles and rough surface of GFRP rebars provided further resistance to slip which consequently improved the bond strength.