Viscosity enhancement of self-consolidating cement-tailings grout by biomass fly ash vs. chemical admixtures

Mechanical Properties and Microstructural Features of Biomass Fly Ash-Modified Self-Compacting Coal Gangue-Filled Backfill

“…After the screening, TSs and CGs with particle sizes ranging from 0 to 2 mm and 16 to 25 mm were used, respectively. More details of TSs and CGs have been reported in our previous studies [ 2 , 6 ]. Tap water was used for all experiments in this study.…”

“…The mixture proportions of SCFB samples are presented in Table 2 . Four different dosages (i.e., 0%, 30%, 40%, and 50%, by mass of cement) of BFA were considered in the OPC replacement according to our published studies [ 2 , 6 ]. In this study, the solid mass fraction of 60% and w/c ratios of 0.8 and 1.0 were chosen to prepare the fresh TS pastes.…”

“…In this study, the solid mass fraction of 60% and w/c ratios of 0.8 and 1.0 were chosen to prepare the fresh TS pastes. The workability of fresh TS pastes was identified based on GB/T 2419-2005 and ASTM C 939-02 [ 6 ]. The flow diameters of the fresh TS pastes in this study were controlled in the range of 25 to 40 mm according to the minimum viscosity method, while the flow times were measured to be less than 15 s according to the flow cone method; in this way, no significant bleeding or separation were observed among the mixtures.…”

“…The costs and CO 2 emissions of raw materials are listed in Table 3 . It should be noted that CG, TS, and BFA used in this study are considered solid wastes, and the costs and CO 2 emissions of TS and BFA are derived from transporting them to the mined sites, with the transportation distance of 25 and 35 km for TS and BFA, respectively [ 6 ]. The calculation of strength efficiency, cost index (C P , USD/m 3 ·MPa), and embodied CO 2 index (CI, kg/m 3 ·MPa) of SCFBs can be found in the Refs.…”

“…Solid waste management has gradually become a global issue because of the problems of land occupation, environmental pollution, and high management costs [ 4 , 5 ]. An important way to reduce the environmental impacts above is to utilize mine solid waste such as tailings sand (TS) and coal gangue (CG) to backfill the mined underground spaces, which not only solves the surface subsidence problem but also promotes sustainable mine development and green development of mineral resources [ 4 , 6 ]. Recently, many kinds of supplementary cementitious materials (SCMs) have been used to replace OPC as the main binder for cemented backfills, which brings advantages of reducing the environmental burden, optimizing the performances at both fresh and hardened states, and improving long-term durability, etc.…”