Cement-stabilized loess as a locally sourced and potentially low-carbon infill for underground mine sealing walls: strength, disintegration resistance and microstructural controls across three coal regions.

Loess is widely available in major coal-producing regions in China and can serve as a locally sourced alternative to conventional concrete for underground mine sealing-wall backfill. This study investigated the strength, water-induced disintegration resistance, microstructural mechanism, engineering economy, and preliminary embodied-carbon performance of cement-stabilized silty loess, sandy loess, and cinnamon soil. Specimens with 0-10% cement were prepared at optimum moisture content, cured for 28 days, and tested using unconfined compressive strength, immersion disintegration, SEM, and XRD. The results show that cement stabilization significantly improves both strength and water stability. At 10% cement content, the UCS values of silty loess, sandy loess, and cinnamon soil reach 3.00, 6.61, and 8.32 MPa, respectively, meeting the strength requirement for sealing-wall backfill. When the cement content is not less than 4%, all specimens show negligible disintegration after 24 h immersion. The stabilization efficiency is strongly controlled by particle-size distribution, with the optimum strength occurring at a silt content of about 48.76%. SEM-XRD analyses indicate that C-S-H, C-A-H, AFt, and CaCO3 improve strength and water stability through bonding, filling, and coating effects. A case comparison shows that cement-stabilized loess can reduce sealing cost, while the preliminary embodied-carbon estimation indicates 53.1-56.1% lower embodied carbon than ordinary concrete per unit volume. These findings suggest that cement-stabilized loess is a locally sourced, economical, and potentially low-carbon backfill material for underground mine sealing walls, although field validation and full life-cycle assessment are still required.