Effect of hydroxypropyl methyl cellulose on coarse tailings cemented backfill: Rheology, stability, strength and microstructure

The bleeding and segregation of coarse tailings cemented backfill (CTCB) seriously affect the effect of roof-contacted filling, and may even lead to safety hazards in mining. The incorporation of hydroxypropyl methyl cellulose (HPMC) may be an effective solution, but its impact on the performance of CTCB and its underlying mechanism remains inadequately understood. This study comprehensively evaluates the rheology (static and dynamic yield stress, and plastic viscosity), stability (bleeding and permeability), strength, and microstructure of containing HPMC. In addition, the mechanism of HPMC on CTCB was further investigated. The research results show that a certain amount of HPMC (<0.1%) can significantly reduce the dynamic and static yield stress of fresh CTCB, while the plastic viscosity increases with the HPMC content. Furthermore, HPMC can significantly improve the bleeding and segregation of CTCB through association and network structure effects. Finally, HPMC delays the hydration of cement, resulting in an early strength reduction of CTCB, but it has little impact on the strength at 28 days.