Effect of initial mixing temperature on mechanical strength, wet-dry durability, and heavy metal immobilization of soil stabilized with solid-waste-based cementitious materials

Stabilizing engineering soils with solid-waste-based cementitious materials (SWCMs) is critical for sustainable construction. While prolonged curing is well-studied, the decisive role of initial mixing temperature, a brief thermodynamic impulse, remains overlooked. This study investigates shield muck stabilization using a Steel Slag-GGBS-Gypsum binder at varying mixing temperatures (20, 40, 60°C). Results reveal mixing temperature acts as a kinetic switch, yielding an apparent global activation energy of 11.6 kJ/mol for early hydration. Elevating to 40°C optimally overcomes nucleation barriers, refining mesopores (30–40 nm) and yielding a highly ordered crystalline matrix (minimum XRD FWHM: 0.141°). This achieves superior 28-day compressive strength (3.7 MPa), wet-dry durability (<5% mass loss), and near-absolute heavy metal immobilization (<LOD). Conversely, 60°C mixing accelerates early hydration (7-day strength: 1.1 MPa, 1.8× control) but triggers a dense shell effect: rapid localized precipitation coats unreacted particles, choking long-term ionic diffusion. This causes 28-day strength regression (2.8 MPa) and severe structural deterioration (13% mass loss). This work demonstrates that precise thermal regulation during brief mixing (<30 min) can provide an energy-efficient alternative to prolonged heat curing for this solid-waste binder system, offering a cleaner, highly efficient pathway for bulk waste recycling.