This study develops a solid waste–based binder (SWB) as a sustainable alternative to ordinary Portland cement (OPC) for deep soil mixing (DSM) applications. The binder was formulated using steel slag (SS), mineral slag (MS), two desulfurisation by-products (DP-1 and DP-2), and a reduced amount of OPC. The optimal composition, determined by way of response surface methodology, was MS:SS:DP-1:DP-2:OPC = 40:20:15:5:20. The SWB-stabilised silt achieved unconfined compressive strengths (UCS) of 1.99 MPa at 7 days and 3.21 MPa at 28 days, with notable synergistic effects between MS and SS. A predictive model for 28-day UCS incorporating moisture and binder content was established. Hydration reactions produced cementitious gels with minimal heavy metal leaching. Full-scale DSM pile tests showed that SWB-treated piles (60 and 70 kg/m) reached bearing capacities of 220 and 260 kN, outperforming OPC-treated piles (160 kN at 60 kg/m), and exhibited higher quality indices. SWB-treated piles reduce total carbon dioxide emissions by more than 70% and binder material costs by over 60% compared with OPC, yielding a more than three-fold improvement in carbon efficiency. As a sustainable binder with technical, environmental, and economic viability, SWB directly contributes to UN SDG 11 by improving urban infrastructure in climate resilience and resource efficiency.
Jiang et al. (2026) studied this question.