Experimental study on fatigue bond behaviour between basalt fibre-reinforced polymer bars and recycled aggregate concrete

Abstract

The bond performance between fibre-reinforced polymer (FRP) bars and recycled aggregate concrete (RAC) affects their combined working ability and further influences the bearing capacity and deformation resistance of FRP bar-reinforced RAC structures. In addition to static loads, many structures such as roads, bridges and subways usually bear fatigue loads during their service periods. Therefore, to provide theoretical and experimental references to the fatigue bond design of FRP bar-reinforced RAC structures, this study systematically investigated the fatigue bond behaviour between basalt fibre-reinforced polymer (BFRP) bars and RAC. Pull-out tests were carried out considering the effects of the surface shapes of BFRP bars, bar diameters, concrete types, fatigue stress levels, and fatigue cycles. Based on the damage at the bond interface, the corresponding bond mechanism was analysed and the bond stress–slip characteristics were summarised. Furthermore, the effect of design parameters on the bond stiffness, slip, bond strength, and residual bond strength was revealed. Different surface shapes of BFRP bars induced different bond mechanisms. Moreover, fatigue loads mainly affected the bond behaviour by eliminating the imperfections and accumulating the damage.