Flowability of ultrafine-tailings cemented paste backfill incorporating superplasticizer: Insight from water film thickness theory

To improve the flowability of ultrafine-tailings cemented paste backfill (UTCPB) while keeping water content low, superplasticizers (SP) are usually used. The water film thickness (WFT) theory was introduced to investigate the flowability of UTCPB incorporating SP. The obtained results show that the packing density of particles increases significantly with the increase of SP dosage due to the improved particle size distribution of the flocs by de-agglomeration effect of SP. The flow spread of fresh UTCPB can be characterized by the unary exponential-type function of WFT to some extent due to the weakened direct effect of SP dosage by high water content. Flocs still exist in the fresh UTCPB incorporating SP and the WFT of flocs (FWFT) can be regarded as the only factor controlling the flow performance of fresh UTCPB. The results presented in this study will contribute to a better understanding of the flow behaviour of UTCPB with SP. [Display omitted] •Effects of superplasticizer on flowability of UTCPB were investigated from WFT theory.•The flow behaviour of the UTCPB incorporating SP before and after the threshold WFT is quite different.•Superplasticizer influences UTCPB flowability through changing FWFT.