Performance of BFRP-reinforced concrete slabs exposed to elevated temperatures: an experimental and analytical study Available to Purchase

Basalt fibre-reinforced polymer (BFRP) bars have attracted increasing attention as corrosion-resistant reinforcement for concrete structures; however, their structural performance under elevated temperatures remains insufficiently understood. This study experimentally investigates the tensile behaviour of BFRP bars and the flexural response of BFRP-reinforced concrete short slabs subjected to sustained elevated temperatures. Tensile tests on BFRP bars were conducted under steady-state heating conditions at room temperature, 210°C, 300°C, and 500°C, representing critical thermal degradation stages of FRP composites, including polymer matrix softening, progressive fibre–matrix degradation and severe thermal decomposition. In addition, reinforced concrete short slabs were tested under flexural loading while exposed to room temperature, 200°C and 600°C to evaluate the structural response under moderate and severe thermal exposure conditions. The results showed that the tensile strength of BFRP bars decreased by approximately 34% at 210°C, 22% at 300°C and 93% at 500°C compared to ambient conditions, while the elastic modulus remained relatively stable up to 300°C. The flexural capacity of BFRP-reinforced concrete short slabs decreased by approximately 20% at 200°C and 54% at 600°C, accompanied by substantial stiffness degradation and increased deflection capacity. Although energy absorption increased at elevated temperatures, this behaviour was primarily associated with bond deterioration, stiffness reduction and progressive damage development rather than improved structural performance. The study also proposes preliminary temperature-dependent reduction models for BFRP tensile properties and evaluates the applicability of ACI 440 design provisions under elevated temperatures. The findings provide important experimental insight into the thermal performance and failure mechanisms of BFRP-reinforced concrete members and contribute toward the development of elevated temperature-resilient design approaches for FRP-reinforced structures.