Bond Performance of Sanded Surface and Threaded Smooth Gfrp Bars

Steel Reinforcement corrosion has been reported to be a major contributor in the deterioration of concrete structures. The use of FRP bars as reinforcement in concrete structures has proven to provide an effective solution for this durability issue [1]. The physical and mechanical properties and surface shape of GFRP bars are significantly different from steel bars. This difference cause GFRP bars to have lower bonding properties with concrete than steel bars causing bond performance to be a major concern when designing GFRP reinforced concrete elements [2]. Several pullout tests have been done to evaluate bond strength of FRP bars which is a major factor in estimating development length [3-5]. The ACI 440.1R-15 [3] defines development length as the embedment in concrete required to transfer the force in the bar through bond (equation 10.1a). The used GFRP bars in this study had a guaranteed tensile strength (mean tensile strength of test specimens minus three times standard deviation [3] of 121 ksi (834 MPa). This value falls within the range of the ACI 440.1R-15 GFRP bar tensile strength values of 70 to 230 ksi (483 to 690 MPa). Discussion and Results