Time-dependent rheological properties and mechanical performance of fresh cemented tailings backfill containing flocculants

The paper presents the results of an experimental study on time-dependent rheological properties and mechanical performance of fresh cemented tailings backfill (CTB) mixtures with flocculants (Anionic-type polyacrylamide). The rheological and mechanical parameters of CTB samples with different binder contents (cement/tailings ratio of 1/10 and 1/20) were prepared and tested at different curing ages. The thermal gravity analysis was resorted to investigate the hydration products of CTB samples with and without flocculants. The microstructure evolution and zeta potential of the fresh CTB mixtures were investigated as well. The results show that the flocculants have negative influence on rheological behavior and mechanical strength of fresh CTB. The apparent viscosity of fresh CTB mixtures decreased sharply at first with the increase of shear rate, and eventually maintained a constant value. The increasing of cement content and curing age leads to an increase in the apparent viscosity of fresh CTB. The fresh CTB mixture with flocculants has higher yield shear stress than that without flocculants, and the yield stress increases as the c/t ratio increases. CTB samples with flocculants present a lower strength than the flocculants-free CTB. Within 7 days curing age, the effect of flocculants on the strength of CTB is negligible, while the CTB with flocculants cured at 28 days shows a strength decrease in comparison to the flocculants-free CTB.