Failure Mechanisms of Basalt Fiber Concrete Under Splitting Tensile Tests and DEM Simulations

To address the cracking problem caused by the weak tensile performance of concrete, this study investigates the failure mechanisms of basalt fiber-reinforced concrete under different fiber contents, single-blend, and mixed-blend schemes through splitting tensile tests and discrete element method (DEM) simulations. The tests employ 0.1–0.3% of 18 mm single-blend fibers and 6 mm:12 mm:18 mm (3:4:3) mixed-blend schemes, and PFC software is used to simulate crack propagation in fiber-reinforced concrete. The results show that the optimal 0.2% content of 18 mm single-blend fibers enhances the splitting tensile strength by 10.8%, whereas excessive 0.3% content reduces the strength by 7.8% due to poor dispersion. The mixed-blend scheme, via gradient crack-resisting effects of multi-scale fibers, increases the strength by 7.43% compared with the single-blend group at the same fiber content. DEM simulations reveal that fibers delay crack propagation through stress concentration transfer: single-blend fibers render tortuous crack paths, while mixed-blend fibers form three-dimensional crack networks, transforming the failure energy dissipation mode from single pull-out to multi-stage consumption. This research provides theoretical basis and optimization strategies for the anti-cracking design of basalt fiber-reinforced concrete.