Flowable clay stabilization using solid waste-based cementitious materials: Performance, mechanisms, and low-carbon features

To reduce the high carbon emissions associated with conventional cement-stabilized clay, this study primarily utilized industrial solid wastes—soda residue (SR), ground granulated blast furnace slag (GGBS), and phosphogypsum (PG)—to develop a novel alkali-activated stabilizer, denoted as GMA. The GMA comprises 80 % solid waste (mass ratio SR:GGBS:PG = 10:81:9) and only 20 % Portland cement (PC). Results indicate that at a 14 % dosage, the 28-day unconfined compressive strength of clay stabilized with GMA reached 1778.36 kPa, corresponding to 96.5 % of that achieved by 14 % pure cement (CMA14), while also exhibiting favorable workability (flow decreased by only 17.2 % within 2 h and the slightly extended setting time provided a sufficient construction window). Microstructural analysis revealed a synergistic effect promoting the formation of hydration products such as calcium silicate hydrate (C-S-H) gel and ettringite (AFt), which densified the microstructure. Importantly, economic and environmental assessments demonstrated significant advantages: GMA14 produced approximately 89.1 kg CO₂/m³ at a cost of ∼134.7 CNY/m³ , whereas CMA14 generated ∼226.8 kg CO₂/m³ at a cost of ∼272.2 CNY/m³ , representing reductions of ∼60.7 % in CO₂ emissions and ∼50.5 % in cost. This technology achieves comparable performance while reducing cement usage by 80 %, providing a key technical pathway for industrial solid waste valorization and low-carbon geotechnical engineering.