Mechanical Properties and Microstructure of Iron Tailings Cemented Paste Backfills Using Carbide Slag-Activated Ground Granulated Blast-Furnace Slag as Alternative Binder

Abstract

For rational disposal of solid wastes, low-cost cemented paste backfills (CPB) were prepared with iron tailings, ground granulated blast-furnace slag (GGBS), and calcium carbide slag (CS). To ensure that CPB can be effectively utilized in mine backfill projects, the effects of solid contents, GGBS content, CS/GGBS ratio, and mixing water on the workability and mechanical properties of CPB were investigated. The results indicated that when the solid content was 70%, the GGBS content was 14%, the CS/GGBS ratio was 0.4, the mixing water was tap water, the fluidity of fresh CPB slurry was 167 mm, and 28d unconfined compressive strength (UCS) of CPB reached 2.89 MPa, at which time the effect of the activation of the GGBS with CS was optimal. The analysis of X-ray diffraction (XRD), scanning electron microscopic imaging (SEM), thermogravimetric analysis (TG-DTG), and Fourier transform infrared spectroscopy (FTIR) demonstrated that the hydration products are mainly C-S-H gels, C-A-S-H, hemicarbonate, and hydrotalcite in CS-GGBS cementitious material. The C-S-H gel content gradually increased with increasing curing time and CS content (15%–35%). When the CS content was increased to 25%, the C-S-H gel content significantly increased, which improved the overall structural compactness and increased the UCS of CPB.

Effect of Content and Length of Polypropylene Fibers on Strength and Microstructure of Cementitious Tailings-Waste Rock Fill

“…To attain the required mechanical strengths of CTB while maintaining its rheological properties [38], the proportion of each component must be determined [39]. Various extra materials such as sand [40,41], fiber [42,43], and pozzolans [44,45] have been recently used to reduce the backfill costs while increasing its strength behavior. Since ROM ore is also crushed into finer particles to boost ore recovery [46], the tailings employed for CTB making can easily cause low UCS values [47].…”

The Failure Mechanical Properties of Cemented Paste Backfill with Recycled Rubber

“…It was found that the addition of straw fiber increased the tensile properties of the CPB, and it was also found that this strengthening effect was weakened when the curing time was increased. The above-mentioned research demonstrated that adding substances to CPB increases its toughness [28][29][30][31][32]. However, to date, there have been few studies on the influence of rubber on the mechanical properties of backfill.…”