Preparation and Microstructure of Alkali-Activated Rice Husk Ash-Granulated Blast Furnace Slag Tailing Composite Cemented Paste Backfill

Abstract

At present, the research on rice hull ash and cement-based materials as cementitious materials continues to deepen. Low-cost rice hull ash replaces part of Portland cement, which plays a dual role in saving material costs and improving environmental benefits. In this study, alkali-activated rice husk ash (RHA) and ground granulated blast furnace slag (GGBS) were used to prepare cementitious material. The influence of RHA dosage on the strength, slump degree, and coagulation time of cementitious material was studied. On this basis, tailing was used as an aggregate based on the orthogonal design method and the bone–gel ratio, modulus, and alkali content were taken as variable factors, with strength and slump degree taken as the targets. A new cemented paste backfill (CPB) was prepared and mix ratio optimization was carried out. The strength formation mechanism of cementitious material and CPB was explored by combining scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD). The results of this study show that with the increase in RHA mixing, the unconfined compressive strength (UCS) of the gelling material purification slurry showed a tendency first to increase and then decrease. When the amount of RHA was about 10%, the internal structure became denser, more C-S-H gel was generated, and greater strength could be obtained. The specific surface area of RHA is high, and a small amount of RHA can fill the internal pores, making the internal structure of concrete more dense. The active silica content in RHA is relatively high. The addition of RHA can appropriately improve the strength of the material, which is of certain significance to our material research. Finally, the micro-analysis of RHA-GGBS clean slurry, the analysis of influencing factors of fluidity and strength, and the optimal mix proportion of alkali-activated RHA-GGBS-based backfill are put forward.

Characterisation of strength and deformation characteristics of alkali-activated rice husk ash filler-assemblage perimeter rock

“…The gelling materials used in this experiment were RHA and slag, the aggregate was tailing sand, and the exciter solution materials were NaOH, water glass and water. The RHA accounted for 10% of the cementing material, the fixed slurry concentration was 83%, the alkali-activated modulus was 1.0, the amount of alkali used was 4% of the mass of the cementing material, and the water-cement ratio was 0.35 32 . The above materials and proportions were used to make the surrounding rock slurry and filling slurry, and the slurry was poured into the Φ 50 mm × L 100 mm mold that had been well oiled.…”

The Failure Mechanical Properties of Cemented Paste Backfill with Recycled Rubber

“…As a safe and environmentally friendly disposal method for tailings, backfilling has significant advantages in controlling surface deformation and in improving ore recovery. Its benefits for use in underground mines are being recognized increasingly around the world [1][2][3][4][5][6][7]. The materials comprising cemented paste backfill (CPB) are important in maintaining mine safety and stability [8][9][10][11].…”

Effect of Waste Clay Bricks on the Performance of Cemented Tailings Backfill and Its Damage Constitutive Model

“…Cheng et al [27] found that applying fly ash to backfill materials can reduce drying shrinkage. Zhao et al [28] used activated rice husk ash and ground granulated blast furnace slag to prepare cementitious materials for cement slurry backfill and found that 10% rice husk ash can achieve higher strength. Yue [29] and Zhang et al [30] found that waste glass can replace some cement or be used as a binder for CTB with low-purity metakaolin, which can reduce backfilling costs.…”