The effect of solid components on the rheological and mechanical properties of cemented paste backfill

Abstract

An experimental study is conducted to investigate the effect of solid components on the rheological and mechanical properties of cemented paste backfill (CPB). Based on the paste consistency, 78wt.% could be a critical value for the solid contents. The mechanical strength increased proportionally with the increase of solid contents. The paste backfill samples prepared with 80wt.% solid contents have a maximum unconfined compressive strength (UCS) of 7.26MPa at a curing time of 28days. A large binder proportion could weaken the consistency of the paste. The slump height drops from 27.5 to 23.5cm when the bind proportions increase from 6.25wt.% to 25wt.%. The long-term mechanical performance increases significantly as the binder proportion increased. The UCS of the CPB sample with 8.33wt.% binder is five times larger than the sample with 6.25wt.% binder. A 25wt.% addition of ungrounded slag causes the slump height to drop from 13 to 25.4cm, mainly due to the decrease in the friction and void spaces between particles. However, the addition of coarse slag would weaken the mechanical properties of the CPB. The UCS of the samples without slag is almost two times larger than the UCS of the samples with 25% slag addition. The addition of soluble glass to the paste mixture appeared to improve the initial setting process. The initial setting time decreases from 846 to 108min when the accelerator addition increases from 1.1wt.% to 3.3wt.%.