Citation: | YU Yongchun, ZHANG Lei, WANG Haifeng, ZHAI Huichao, SUN Changkun. Effect of slag powder on mechanical properties and microstructure of fine tailings cemented backfill[J]. CHINA MINING MAGAZINE, 2022, 31(10): 145-151. DOI: 10.12075/j.issn.1004-4051.2022.10.013 |
The effects of different slag powder content on the early and long-term strength of the backfill and the fluidity and bleeding rate of the filling slurry are studied.The hydration products of the backfill at a specific age are characterized by utilizing X-ray diffraction(XRD) and scanning electron microscope(SEM), and the strength development mechanism is revealed.The results show that at the early stage of backfill curing(3 d), the addition of slag powder is not conducive to the development of backfill strength, and the higher the addition amount is, the greater the reduction backfill strength.After the curing age exceeds 7 d, the effect of slag powder on the strength improvement of backfill begins to appear, and the longer the curing age of backfill is, the more pronounced the compressive strength improvement effect is under the exact dosage.When the filling concentration is 70%, the cement-sand ratio is 1:6, and the slag powder content is 80%, the compressive strength of the backfill after curing for 28 d and 90 d is 5.02 MPa and 6.53 MPa, respectively, which is 211.80% and 305.59% higher than that of the backfill after curing for 7 d.A small amount of slag powder can reduce the fluidity and bleeding rate of the filling slurry to a certain extent, but when the slag powder content is high, both the fluidity and bleeding rate of the filling slurry are improved to a certain extent.The increased number of hydration products such as C-S-H and ettringite(3CaO·Al2O3·3CaSO4·32H2O) in the backfill caused the strength of the backfill to be higher than that of the pure cement backfill.