Effect of superplasticizer type and dosage on fluidity and strength behavior of cemented tailings backfill with different solid contents

This paper presents the coupled effect of solid content and superplasticizer type and dosage on the fluidity and strength properties of cemented tailings backfills (CTB). A total of three different superplasticizers (namely, naphthalene, ether-based and ester-based polycarboxylate) were used at a ratio varying from 0% to 0.5% by mass of CTB. The CTB mixes were proportioned with a solid content of 65%, 66%, 68% and 70%. The unconfined compressive strength tests were performed on CTB samples after 3, 7 and 28 days of curing period. The obtained results show that the effect of superplasticizer on CTB performance depends on type and dosage of the superplasticizer used as well as solid content. The naphthalene-based polycarboxylate admixtures demonstrate the best improvement on fluidity behavior of fresh CTB mixture. For a given superplasticizer type, increases in the dosage of superplasticizer and decreases in the solid content lead to better workability of CTB samples. When increasing solid content, fresh CTB with high superplasticizer dosage performs a relatively low rate of decrease in the workability. A relatively high solid content and superplasticizer dosage have greatly contributed to improved mechanical strengths, especially at 28-day curing age, mainly due to a major reduction in water-to-cement ratio and porosity.