Review of hydration and hardening properties of steel slag in mine filling cementitious materials

Using steel slag for the preparation of mine backfill materials is vital to utilizing its resources. Therefore, this study reviewed the impact of different processing technologies and sources on the physical and chemical properties of steel slag, analyzed the application modes and hydration mechanisms of six kinds of steel slag backfill cementitious materials, and discussed the advantages, disadvantages, and development trends of steel slag in the field of mine backfill. This study indicates that: (1) Desulfurized gypsum could promote the hydration and dissolution of steel slag, while cement clinker, slag, and fly ash provide an alkaline environment for steel slag hydration, and silica fume offers a large amount of highly reactive silicon; (2) Steel slag could improve the workability of filling slurry and increase the late strength of backfill, extend the setting time of backfill material and reduce the early strength of backfill. (3) The addition of steel slag could enhance the plastic deformation characteristics of the backfill body, therefore offering references for the prevention and control of dynamic impact hazards in coal mines.