Utilization of Coal Fly Ash as a Supplementary Cementitious Material in Shotcrete for Slope Reinforcement in Mining Areas
Utilization of Coal Fly Ash as a Filler in Shotcrete
DOI:
https://doi.org/10.55981/jsmi.2026.14964Keywords:
Fly ash, Mortar, Slope stabilizationAbstract
The extensive use of Portland cement in mortar for slope reinforcement contributes significantly to carbon dioxide (CO2) emissions, highlighting the need for more sustainable construction materials. This study investigates the utilization of coal fly ash as a supplementary cementitious material (SCM) in shotcrete mortar for slope stabilization in mining areas. Mortar specimens were prepared using soil from the middle layer, selected due to its higher density, and fly ash contents of 0%, 7%, 14%, 21%, and 28% as partial cement replacements. The physical properties of the soil were evaluated, while the mortar was assessed through compressive strength and water absorption tests. Microstructural and compositional characteristics were analyzed using X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier-transform infrared (FTIR), and scanning electron microscopy–energy dispersive X-ray (SEM–EDX). In addition, slope stability analysis was conducted using the limit equilibrium method (LEM) to evaluate the effectiveness of fly ash–modified mortar in soil nailing systems. The results demonstrate that fly ash significantly impacts mortar performance through pozzolanic reactions and microstructural densification. The highest and most stable compressive strength was achieved at 21% fly ash content, which provides a more suitable balance between mechanical strength and durability. Characterization results confirm the formation of additional hydration products such as calcium silicate hydrate (C–S–H) and calcium aluminate silicate hydrate (C–A–S–H). Slope stability analysis demonstrates an increase in the factor of safety (FoS) from below 1.0 to 1.039, reducing the probability of failure to 4%. Overall, coal fly ash is proven to be an effective and sustainable SCM for shotcrete mortar, enhancing mechanical performance, durability, and slope stability while reducing cement consumption.
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