Discarded mask fiber-glass powder composite enhanced microbially induced calcite precipitation-treated calcareous sand: Mechanical property and micro-mechanism
摘要
The low bearing capacity of calcareous sand challenges island reef engineering. While microbially induced calcite precipitation (MICP) is an emerging reinforcement method, it suffers from brittleness and low mineralization efficiency. This study proposes a novel composite strategy combining MICP with discarded mask fibers (DMF) and waste glass powder (GP) to address these limitations. Both DMF and GP individually boost microbial mineralization by offering nucleation sites, enhancing bacterial retention, and improving Ca2+ utilization. The composite system significantly outperformed pure MICP. Optimal strength was achieved at a ratio of 6 mm 0.2% DMF and 13 µm 4% GP (by weight of sand), yielding a maximum unconfined compressive strength (UCS) of 1327 kPa. This is a 136% increase in UCS and a 143% increase in the toughness index over the MICP-only group. Furthermore, the synergy improved deformation performance, with the deformation index surging by 396% under 12 mm 0.2% DMF and 13 µm 4% GP. GP particles fill voids to densify the cementation matrix, while the DMF network provides bridging action, enhancing ductility. Microstructural analysis confirms a robust framework of dense GP-CaCO3 clusters interconnected by the DMF network. This research presents a novel, sustainable solution utilizing upcycled waste for island reef construction.