Abstract: In order to enhance the mechanical properties of ultra-fine tailing backfill and reduce the cost of filling minedout areas,a novel solid waste-based binder was developed as a cost-effective alternative to cement. The effects of this new binder and cement on the flowability of backfill slurry and the strength performance of backfill were comparatively analyzed through macroscopic experiments and microstructure characterization. The strength mechanism of the novel binder was also investigated. The results indicated that the slurry prepared with the novel binder exhibited less bleeding and better liquidity compared to cement slurry,with a slump increase of 7. 27%-12. 21% under the same mix proportions. The liquidity of both slurry decreased with increasing binder-to-tailings ratio. The compressive strength of the backfill prepared with the novel binder was significantly higher than that of cement backfill,with an improvement of 24. 497%-138. 931%. The strength of both backfill positively correlated with the binder-to-tailings ratio and curing age. The novel binder produced more hydration products ( C- S -H and AFt),reduced porosity,and formed a denser matrix,effectively improving the strength of the backfill compared to cement. These findings provide critical theoretical insights and practical guidance for the application of novel solid waste-based binders in reinforcing ultra-fine tailings backfill. 

Key words: solid waste base,tailings backfill,liquidity,compressive strength,strength enhancement mechanism