Analysing the bond performances of composite rebars made with carbon and aramid fibers by using hinged beam method

Nowadays, fiber reinforced composite rebars are produced by using glass fiber, basalt fiber, aramid fiber, and carbon fiber. In these composite rebars, continuous fibers are used as a reinforcing material and epoxy resin is used as a matrix material. These new composite rebars can be produced in different surface forms with the aim of representing the ribs that are on the surface of steel reinforcements. In this study, bond behavior of steel rebar, carbon fiber reinforced composite rebar and aramid fiber reinforced composite rebar were investigated comparatively. The hinged beam method, which is one of the bond experiments in bending, was used while determining the bond relations between reinforcement bars and concrete. In the experiments, two different concrete types employed to determine the effect of concrete quality (C35 and C50), two different embedment lengths employed to determine the effect of embedment lengths (10 and 20 times the diameter of the reinforcement), two different surfaces employed to determine the effect of surface properties of fiber reinforced composite rebars on bonding (sand coated and helically wrapped) and two different diameters employed to determine the effect of reinforcement diameter (8mm and 12 mm) on bonding were used as experimental parameters. As a result, it was found that composite rebars have a much higher tensile strength than steel rebar, and these composite rebars with sand coated surface produced by both aramid and carbon fibers show a much better bond performance compared to steel reinforcement. Besides, bond performance of composite rebars is very variable depending on the form of surface form.