Preparation of a New Type of Cemented Paste Backfill with an Alkali-Activated Silica Fume and Slag Composite Binder

Abstract

A new type of cemented paste backfill (CPB) was prepared using sodium hydroxide (NaOH) as the activator, slag and silica fume (SF) as the binder, and tailings as the aggregate. The effects of proportion of replacement of 0%, 5%, 10%, 15%, and 20% silica fume on the properties of CPB were studied. The strength formation mechanism of CPB was explored through a combination of scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and Fourier transform infrared (FTIR) spectroscopy. The SEM images were analyzed by IMAGE J software, and the porosity of CPB with different silica fume contents was obtained. The results show that as the amount of silica fume increases, the unconfined compressive strength (UCS) increases first and then decreases. When the amount of silica fume was approximately 5%, CPB with a larger UCS can be obtained. When the silica fume content increased from 0% to 5%, because silica fume has good activity and small particles, more calcium silicate hydrate (C–S–H) gels and Mg-Al type layered double hydrotalcites (LDHs) were generated in CPB, which made it denser and improved its strength compared with the non-silica fume group. C–S–H gels were the main source of CPB strength. With a further increase in the amount of silica fume, thaumasite produced inside of CPB, reducing the content of C–S–H gels. Moreover, due to the expansion of thaumasite, it is easy to generate a large number of micro cracks in CPB, which weakens the strength of CPB.

Effects of slag-based cementitious material on the mechanical behavior and microstructure evolution of copper-base cemented tailings backfill

“…In recent times, numerous academics have dedicated significant efforts towards developing and enlarging novel cementitious substances and have achieved notable success in investigating the viability of partially or fully substituting OPC (Chen et al, 2019a;David and Chen, 2015;Eker and Bascetin, 2022;Ercikdi et al, 2009a;Serge et al, 2007;Sun et al, 2020;Xu et al, 2020b;Yan et al, 2019). Among these substitutes, cementing agents incorporating pozzolanic materials as a matrix, such as blast furnace slag (Eker and Bascetin, 2022;Xu et al, 2020b;Yan et al, 2019) and fly ash (David and Chen, 2015), have garnered considerable attention due to their relatively economical nature and stable performance.…”

The Failure Mechanical Properties of Cemented Paste Backfill with Recycled Rubber

“…Therefore, improving the impact resistance of filling bodies has always been the main research direction [19]. The improvement of the impact resistance of CPB is mainly achieved by reducing its brittleness and increasing its toughness [20][21][22][23].…”

Preparation a High-Performance of Gangue-Based Geopolymer Backfill Material: Recipes Optimization Using the Taguchi Method

“…Studies have demonstrated that geopolymers exhibit notable characteristics such as high strength, erosion resistance, impermeability, and good excellent long-term workability [17]. Both domestic and international scholars have sought to improve the flowability [18] and strength development [19] of filling materials through various measures, including the use of admixtures [13,20], adjustments to the amount of gelling material [21,22], and the selection of excitation agents [19]. However, many of these methods can be costly.…”