Abstract: This study investigates the disposal and resource reutilization of muck generated from slurry shield tunneling on the Taizhou Metropolitan Railway S2 Line. A low-carbon composite solidification material, formulated primarily from slag, fly ash, and cement, was developed to modify shield-excavated waste soil for reuse as synchronous grouting material. Laboratory experiments were conducted to assess the fluidity, unconfined compressive strength (UCS), and microstructural characteristics of the grouting material produced using the proposed solidification system. The results demonstrate that the solidified and modified shield muck can effectively substitute conventional synchronous grouting materials. Under the optimal mix design, the slurry exhibits a 6 min fluidity of 200 mm, a 30 min fluidity of 160 mm, a 2 h bleeding rate of 1.4%, a 28 day stone formation rate of 98.7%, and a 28 day compressive strength of 2.53 MPa. Microstructural analyses further reveal that the solidification mechanism is governed by the synergistic effects of alkali activation and hydration reactions, which generate CSH gel and ettringite, providing both cementation and pore-filling functions.

Key words: Slurry Shield Tunneling, Waste Soils, Mechanical Properties, Microstructure, Synchronous Grouting