The Effect on Mechanical Properties and Microcosmic Morphology of Basalt Fiber-Reinforced Recycled Concrete after High Temperatures

ABSTRACT This study aims to enhance the mechanical properties of recycled aggregate concrete (RAC) by adding basalt fiber (BF). Based on experimental results, the optimum mix proportion of RCBF30-0.15 was obtained (The specimen with a replacement percentage of recycled aggregate of 30% by weight and an addition percentage of BF of 0.15% by volume). The compressive strength exhibits the fastest rate of decline between 600°C and 800°C. At 800°C, the tensile strength and compressive strength decrease by 55.99 % and 77.56 %, respectively, compared with their values at room temperature. Overall, excessive temperatures have an adverse effect on the mechanical properties of basalt fiber reinforced recycled concrete (BFRC). Through theoretical analysis of experimental data, constitutive models of BFRAC were established under tensile and compressive stresses before and after high temperatures. Finally, finite element simulations were performed, and predictive models for both the macroscopic and microscopic properties were established. This study advances the broader implementation of RAC, promotes environmental sustainability, and establishes a theoretical framework for post-elevated–temperature reinforcement strategies in RAC applications.