Abstract The disposal of TBM muck has become a pressing issue in tunnel construction. This study addresses the utilization of 295,000 m3 of gneiss muck excavated from the DXL Tunnel in western China by modifying it with low‑calcium fly ash (FA), ground granulated blast‑furnace slag (GGBS), carbide slag (CCS), and basalt fiber (BF) to produce a roadbase material. The optimal mix, designated X‑FGC (FA:GGBS:CCS = 9:4:1 with 0.3% 12‑mm BF), was determined via response surface methodology.
