Bond behaviour of recycled aggregate concrete with basalt fibre-reinforced polymer bars

Abstract The combination of recycled aggregate concrete (RAC) and fibre-reinforced polymer (FRP) bars can effectively avoid corrosion. Bond performance is an important factor affecting the bearing capacity of RAC structures reinforced with FRP bars. In this study, the effects of the contact interface, concrete type, bar dimension, and surface shape of FRP bars on the bond performance of 39 pull-out specimens were investigated. The failure mode was analysed, and the evolution of damage at the interface between the concrete and basalt fibre-reinforced polymer (BFRP) bars was investigated. Moreover, the bond mechanism and the characteristics of the bond stress-slip curves were revealed. The effects of the design parameters on the bond strength, bond stiffness, residual bond strength, and slip were determined. A constitutive model was proposed to simulate the bond stress-slip relationship. Formulae to estimate the characteristic parameters were derived to develop the proposed model. The proposed model was shown to agree well with the experimental bond stress-slip curves. Finally, the development length of the BFRP bar-reinforced RAC structures was determined. The findings from this study could promote the application of BFRP bar-reinforced RAC structures and provide an experimental and theoretical basis for the design of their bond performance.