Recycling microfines of manufactured sand into fabricating robust highly flowable cement-tailings grout

Abstract

To enhance the poor performance of highly flowable grout cement tailings grouts (CTGs) in a more sustainable way, this study proposes an effective measure by using microfines of manufactured sand (MMS) to improve the static stability and homogeneity of CTGs at both fresh and hardened states. In this work, iron tailings sand (TS) was partially replaced by MMS in equal volume, effect of MMS on the flowability and static stability at fresh state and mechanical properties of CTGs was illustrated. The density method, Backscattered electron microscopy (BSE) and thermogravimetric analysis (TGA) were employed to determine the homogeneity and microstructure. The results show that the replacement of TS by MMS improves its static stability and the homogeneity after hardening, the optimal content of MMS is 20 % by volume. The replacement of TS by finer MMS particles modifies the viscosity of fresh grouts and also favors the mechanical performances and microstructure development by providing nucleation sites. These findings provide a reliable and low-cost way for preparing highly robust materials for grouting or backfilling with excellent static stability and homogeneity.