Effect of waste glass powder on pore structure, mechanical properties and microstructure of cemented tailings backfill

In order to reduce the filling cost of the mine and improve the performance of the cemented tailing backfill (CTB), waste glass powder (WGP) is introduced into the CTB as a substitute for cement in this paper. The study examined pore structure, mechanical properties and microstructure changes of CTB samples based on 0, 10, 20, and 30 % WGP replacement rates. The following conclusions are obtained, the pore size of CTB is divided into micropores, secondary pores, and macropores with the boundary of 20 nm and 200 nm, and the pores in CTB are mainly macropores. The incorporation of WGP can improve the pore structure of CTB. The hydration of CTB with WGP can be divided into two parts. Before the curing time is 56d, cement dominated hydration occurs in CTB. WGP mainly plays the role of micro aggregate effect in filling the pores of CTB, and the strength of CTB decreases with the increase of WGP replacement rate. After 56d of curing, cement hydration rate slows down. The pozzolanic activity of WGP is activated under strong alkaline environment, and the secondary hydration reaction enhances the long-term strength of CTB. Especially for CTB with a replacement rate of 20 %, the particle peeling on the surface of the sample is improved after unconfined compression and its microstructure is more compact, the Ca/Si ratio is significantly increased after long-term curing.