Bond Slip Behavior for CFRP-to-Concrete Joints at Room Temperature

Fiber-reinforced polymer (FRP) composites have increasingly been used in the past 40 years. They are ideal option for external strengthening of reinforced concrete (RC) structures due to their superior properties, including the high strength-to-weight ratio and ease of installment. The structural behavior of strengthened RC beams and the efficiency of the external FRP applied are both highly dependent on the bond performance between FRP and concrete. This paper presents an experimental study on the bond slip behavior of carbon fiber reinforced polymer (CFRP) sheets, applied to concrete structures under room temperature conditions. The experimental investigation involved the strengthening of three concrete prism specimens with CFRP sheets. The prism specimens were tested under a three-point bending setup. The bond slip phenomenon was analyzed using strain gauge readings attached to the CFRP laminate before testing. The calculated model aimed to accurately capture the bond slip behavior and its associated parameters, including the maximum shear stress, and maximum slip. These parameters were compared with theoretically derived formulas available in the literature. The theoretical equations overestimated the FRP stresses when compared to experimental measurements. The comparative analysis assesses the accuracy and reliability of the theoretical derivations by benchmarking it against the experimentally derived bond-slip model for CFRP-to-concrete joints.