Abstract: The resource utilization of marine soft clay is of great significance for enhancing the value of land resources in coastal areas, ensuring the construction projects and achieving green and low-carbon disposal of industrial solid waste. To address the challenge of the stabilizing marine soft clay and to promote the resource utilization of industrial solid wastes, this study developed a composite inorganic stabilizer using coal gangue and fly ash as base materials, and quicklime and sodium silicate as activators. A D-optimal mixture design was employed to optimize the formulation, while SEM, EDS, and PCAS analyses were conducted to investigate the microstructural stabilization mechanism. The results show that at the optimal proportion (coal gangue: fly ash: quicklime: sodium silicate = 0.05:0.30:0.25:0.40), the unconfined compressive strength (UCS) of the stabilized soil reached 692.94 kPa after 28 days. The stabilization mechanism involves the alkali-activated pozzolanic reaction generating C-S-H gels and related products, which fill and densify the soil pore structure, reducing the porosity ratio from 33.1% to 9.58%. This research provides both an effective formulation and theoretical basis for the application of solid waste-based stabilizers in soft soil improvement.

Key words: Peaty Soils, Stabilizers, Additive Optimization, Microstructure, Industrial Solid Waste