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 hours 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. • Solid waste-based stabilizer achieves cement-like clay strength. • Eighty percent cement reduction with comparable engineering performance. • Synergistic activation promoted C-S-H and ettringite formation. • Significant carbon emission and cost reductions in clay stabilization.