Dynamic bond behaviour of fibre-wrapped basalt fibre-reinforced polymer bars embedded in sea sand and recycled aggregate concrete under high-strain rate pull-out tests

Abstract

Using sea sand instead of river sand and recycled coarse aggregates instead of natural coarse aggregates to prepare sea sand and recycled aggregate concrete (SSRAC) can help preserve sand and stone resources, reduce construction costs, and protect ecological environments. However, the chloride ions in sea sand corrode steel bars, posing a safety risk to concrete structures. Fibre-reinforced polymer bars, which have a high strength and are lightweight and chloride corrosion-resistant, are used instead of steel bars to avoid chloride corrosion. In this study, the dynamic bond behaviour of fibre-wrapped basalt fibre-reinforced polymer (BFRP) bars embedded in SSRAC was evaluated via high-strain rate pull-out tests. Ten loading rates were applied to assess the effects of static, seismic, and impact loads on the bond performance. The damage characteristics of the concrete–BFRP bar interface were analysed, and the bond mechanism was ascertained. The characteristics of the bond stress–slip curves were examined, and the effects of the strain rate on the bond strength, slip, and stiffness were investigated. Finally, formulae describing the dynamic effects of these factors on the bond strength, slip, and stiffness were proposed to predict the dynamic bond behaviour. The findings presented herein can guide the application and development of BFRP bar-reinforced SSRAC structures and provide a theoretical basis and experimental support for dynamic design methods to enhance their bond performance.