Experimental study on the tensile properties of fiber-reinforced cemented paste backfill

To address engineering challenges such as cracking and instability in mine backfill caused by insufficient tensile strength, laboratory tensile tests were conducted to investigate the effects of different contents of steel and basalt fibers on the tensile properties of total tailings cemented paste backfill (CPB). Digital image correlation (DIC) technology was employed to observe the evolution of the strain field on the specimen surface, and the fiber reinforcement mechanism was elucidated through scanning electron microscopy (SEM) analysis. The results indicate that after reaching peak tensile strength, steel fiber-reinforced backfill specimens exhibit brittle failure characteristics, whereas basalt fiber-reinforced specimens display ductile failure behavior. Compared to fiber-free reference backfill, the addition of an appropriate amount of fibers enhances tensile strength. Among the tested fiber contents, steel and basalt fibers at 0.6 % content demonstrated the most significant reinforcement effects, increasing tensile strength by 9.14 % and 36.03 %, respectively. Basalt fiber-reinforced backfill exhibited superior overall energy absorption performance compared to the steel fiber-reinforced counterpart. Furthermore, micro-morphological observations of fiber-reinforced backfill and analysis of fiber-matrix interfacial bonding revealed the underlying mechanism of fiber-reinforced tensile strength. The strain field evolution further suggests that basalt fibers promote a more favorable internal stress distribution within the backfill, offering greater advantages in improving specimen strength and toughness. These findings provide a theoretical foundation and experimental support for selecting fiber materials and determining optimal fiber contents in mineral filling projects, significantly contributing to enhancing the stability of mine backfill bodies and ensuring safe mining operations. • Direct tensile strength and energy evolution law of fiber-reinforced CPB are systematically revealed via tensile tests. • A reliable experimental foundation is provided for optimal proportion design of high-performance fiber-reinforced CPB. • DIC and SEM techniques clarify the micro-macro enhancement mechanism of fibers in inhibiting CPB cracking.