The decrease in mechanical properties of concrete has a crucial impact on the long-term service behavior of civil engineering structures. To enhance its durability, a total of 84 reinforced concrete specimens were prepared for the center pullout test, incorporating different concentrations of carbon nanotubes (CNTs) in the concrete and varying diameters of basalt fiber–reinforced polymer (BFRP) and glass fiber–reinforced polymer (GFRP) bars. The impact of CNTs on concrete mechanics and fiber-reinforced polymer (FRP)–concrete bond was examined. The experimental results indicated that the optimal CNT content is 0.3%, at which the bond strength reaches its maximum value of 8.13 MPa. As the diameter of the reinforcement bars increased, the bonding stress gradually increased, and the peak slip at maximum bond stress decreased slightly.
Zhao et al. (Fri,) studied this question.