Abstract: To reduce the reliance on cement in cemented ultra-fine tailings backfill (CUTB),achieve low-cost and low carbon backfilling,and improve its brittle failure characteristics,an all-solid-waste binder (ASWB) composed of ground granu lated blast furnace slag,oil shale residue,phosphogypsum,and carbide slag was developed to completely replace ordinary Port land cement.Recycled tire polymer fibers (RTPF) were incorporated for reinforcement.The macroscopic mechanical proper ties,microstructure,and reaction mechanisms of the all-solid-waste CUTB were systematically investigated through uniaxial compressive tests,thermogravimetric analysis (TG),scanning electron microscopy with energy dispersive spectroscopy (SEM EDS),etc.Furthermore,a damage constitutive model for RTPF-CUTB,incorporating a damage correction coefficient (m),was established based on Weibull statistical damage theory.The results indicate that:① The cementitious performance of the ASWB system for CUTB is significantly superior to that of the OPC system,with 7 d and 28 d compressive strength increased by 57.69%~196.15% and 94.96%~147.90%,respectively.Phosphogypsum effectively promotes early-age strength develop ment,and the 28 d compressive strength reaches a maximum of 2.95 MPa when its dosage is 5% of the ASWB mass.② The main hydration products of the all-solid-waste CUTB are C-(A)-S-H gel and ettringite crystals,which form a dense "gel crystal" interlocking structure,providing microstructural support for strength enhancement.③ The reinforcing effect of RTPF on CUTB outperforms that of polypropylene fibers,with an optimal dosage of 0. 4%,resulting in a strength increase of 10.17%~13.46% compared to the fiber-free system.The established damage constitutive model accurately describes the dam age evolution process of RTPF-CUTB.This study provides a theoretical and technical basis for the green resource utilization of ultra-fine tailings in backfilling and the performance optimization of backfill materials.

Key words: cemented ultra-fine tailings backfill,compressive strength,all-solid-waste binder,recycled tire polymer fi bers,microstructure,damage constitutive model