Enhancing workability, strength, and microstructure of cemented tailings backfill through mineral admixtures and fibers

The study investigates the enhancement of cemented tailing backfill (CTB) performance and cost reduction through the systematic examination of CTB with various fibers (polypropylene, basalt, and straw) and mineral additives. The impact of fiber, rice husk ash, and fly ash on CTB's physical attributes, workability, and microstructure is thoroughly analyzed. The results showed that with the increase of fly ash content, slump increased by 3.77 %, and the bleeding rate, initial setting time and final setting time increased by 10.33 %, 24.67 % and 7.71 %, respectively. Conversely, as the rice husk ash content rises, slump decreased by 1.89 %, while bleeding rate, initial and final coagulation time decreased by 10.33 %, 4.93 % and 5.17 %, respectively. The incorporation of polypropylene fiber, basalt fiber and rice straw fiber results in a reduction in slump by 5.97 %, 5.22 % and 3.73 %, and a decrease bleeding rate decreased by 29.18 %, 27.88 % and 22.86 %, respectively. Moreover, an increase in the content of three kinds of fiber leads to prolonged initial and final setting time of slurry. Fly ash or rice husk ash additions improve CTB compressive strength, with the optimum fly ash content at 15 %. Combining fly ash and rice husk ash further enhances compressive strength, with an optimal content of 16 %. Polypropylene, basalt, and rice straw fiber additions significantly boost sample compressive strength, with an optimal fiber content of 0.6 %. Polypropylene or rice straw fibers inhibit main crack extension, with polypropylene fiber outperforming in crack resistance at 0.6 % fiber content. Increased fly ash or rice husk ash improves microstructure density and forms a stable network support system in CTB. The distribution of polypropylene or rice straw fibers transitions from sporadic to dense, exhibiting bending deformation characteristics indicative of load-bearing and dispersing roles.