Effect of calcined coal gangue powder on the properties of basalt fiber-reinforced concrete

Abstract

To promote the engineering application of coal gangue and fiber-reinforced concrete, this study employed acoustic emission (AE) and scanning electron microscopy (SEM) techniques to investigate the effect of calcined coal gangue powder (CGP) replacement ratios of cement on the compressive and tensile properties of basalt fiber-reinforced concrete (BFRC). Uniaxial compression and splitting tensile tests were conducted on BFRC specimens with four different CGP replacement ratios (0 %, 10 %, 20 %, and 30 %), and the synergistic mechanism between CGP and basalt fibers (BF) was further explored. The AE characteristics delineated four distinct failure stages in BFRC: microcrack propagation, fiber/matrix interface debonding, fiber fracture/matrix cracking, and post-peak failure, and clarified the damage mechanisms for each stage. Moreover, quantitative RA-AF analysis of the AE signals using the Kneedle algorithm confirmed that the failure mode of BFRC was predominantly governed by shear failure. The results indicated that the physical and mechanical properties of BFRC first increased and then decreased with increasing CGP replacement ratios. A 10 % CGP replacement ratio optimally improved the micropore structure and interface bonding performance of BFRC by virtue of the pozzolanic effect, rendering the ultrasonic pulse velocity (UPV), compressive strength, and splitting tensile strength of the C10BF15 group significantly superior to those of other groups. Therefore, 10 % was determined as the optimal replacement ratio.