Utilization of waste rock from a low-carbon perspective: Mechanical performance analysis of waste rock-cemented tailings backfill

To promote low-carbon concepts, conserve resources, and enhance the utilization efficiency of waste rock (WR) and tailings, this study investigated the mechanical performance and destruction characteristics of waste rock-cemented tailings backfill (WRCTB) under layered placement. Through uniaxial compressive strength (UCS) experiments to assess WRCTB specimens under different WR contents and grain sizes, accompanied by scanning electron microscopy (SEM) analysis of their microstructure. The results indicate that with an increase in WR content, the UCS of the WRCTB specimens gradually increased, with an optimal content of 50 %. Additionally, as the grain sizes of the WR increased, the WRCTB specimens’ UCS initially increased and then decreased, where the optimal grain size was 3–7 mm. Compared with the control group (N-WRCTB), the WRCTB specimens’ UCS showed a maximum improvement of 57.9 %. The WRCTB specimens exhibited higher total energy density, dissipated energy density, and elastic strain energy density, with the incorporation of waste rock resulting in a transition from brittle to ductile failure behavior, demonstrating more excellent toughness. Furthermore, the addition of WR altered the failure mode of the WRCTB specimens, shifting the primary failure mechanism from shear to tensile. Cracks developed from the mid-layer, leading to a multi-crack failure mechanism. This research provides valuable perspectives into the effective utilization of solid waste in mining and the design of WRCTB.