Influence of alkaline agents with different contents on strength features, energy dissipation and microscopic behavior of cement-based high‑sulfur tailings fill

Abstract

As high‑sulfur tails encompass abundant pyrite (FeS2), it is easy to form acidic/leachate waters under the action of water and air, which is opposed to cement-based tail fill (CTF)’s strength development. Therefore, the present investigation improves the mechanical/microstructural behavior of cement-based high‑sulfur tailings fill (CHSTF) by adding alkaline agents fly ash (FA) and sodium bicarbonate (SB). Lab findings demonstrated that adding appropriate amounts of FA and SB could significantly increase the UCS value of CHSTF. FA-2%, SB-1% and FS-2% are the best dosage of alkaline agents, and the resultant peak strength is 1.15 MPa, 1.23 MPa and 1.26 MPa. In comparison to None-1: 6, CHSTF's strength increased by 32.18%, 41.26% and 44.41%, respectively. The synergistic effect of FA and SB was significant. On the other hand, the additives not only promoted hydration products' formation, but also increased CHSTF's density and compactness, which significantly enhanced the strength properties and durability of CHSTF. The results could provide new ideas and an experimental basis for the effective treatment and resource reuse of high‑sulfur tailings.