Mechanical performance and pavement response of basalt fiber reinforced coal gangue based composites for sustainable road applications

Abstract Coal gangue is widely generated during coal mining, but its application in pavement materials is limited by insufficient mechanical performance. This study developed a gangue–fly ash–cement–fiber (GFCF) composite and evaluated the effects of basalt fiber dosage on mechanical properties, microstructure, and pavement-scale deformation through laboratory tests, XRD, SEM, and three-dimensional numerical simulations. The results showed that unconfined compressive strength and splitting tensile strength increased with fiber content up to 0.6% and slightly decreased at 0.8%. The 0.6% fiber mixture achieved the highest 28 d UCS and splitting tensile strength of 14.47 MPa and 1.51 MPa, respectively. However, the reduction in compressive resilient modulus with increasing fiber content indicated a strength–stiffness trade-off. Numerical simulations revealed that fiber-dependent material differences had limited effects on settlement, whereas vehicle speed and traffic-load magnitude produced greater deformation variations. XRD and SEM observations qualitatively confirmed matrix densification and possible fiber–matrix interaction during curing. Overall, 0.6% fiber provided the most favorable strength-oriented performance within the tested range, while the numerical results provide comparative evidence for evaluating the pavement-scale response of the GFCF base layer and support the high-value utilization of coal gangue in pavement engineering.