Superior reinforcement efficiency of basalt fibers in geopolymers: Hydration interaction and embodied carbon advantage over carbon fibers

Red mud and iron tailings are significant bulk solid wastes with potential applications in the construction sector. However, challenges such as low early hydration strength and incomplete embodied carbon accounting have limited their industrial utilization. This study explores the incorporation of basalt fibers (BF) and carbon fibers (CF) into red mud‑iron tailings-based geopolymer mortar (RIGM) to enhance the early-age mechanical properties of geopolymers. After 7 days curing, the BF-RIGM exhibited a 36.13 % improvement in flexural strength (6.82 MPa) and a 17.16 % increase in compressive strength (51.34 MPa) compared to RIGM. Additionally, BF-RIGM demonstrated a 17.83 % higher C-A-S-H gel content relative to CF-RIGM. The gel and medium capillary pore volumes increased by 10.96 %, while the embodied carbon was reduced to 352.68 kg CO₂/m³, representing a 33.21 % decrease compared to CF-RIGM. These findings offer valuable insights for promoting the industrial application of solid waste, with a focus on improving performance and reducing environmental impact.