Exploration on using solid waste-derived sulphoaluminate composite as low-cost binder for high-impermeability stabilization of sandy soil

Large-scale utilization of solid waste is the key challenge in building sustainable infrastructure. Given the high demand for sandy soil stabilizers in subgrades, dams and other infrastructure projects and the high permeability of sandy soil, a sulphoaluminate composite cementitious material (SCCM) was developed by incorporating solid waste-derived sulphoaluminate cementitious material (SAC), desulfurized gypsum, ground granulated blast furnace slag (GGBS), and supplementary industrial byproducts, which can be used as high-permeability stabilizers for sandy soil. The economic and environmental assessment revealed that the carbon emission factor of the SCCM throughout their whole life cycle was 135.8 kg/t. The results revealed that the unconfined compressive strength (UCS) of stabilized sandy soil for 28 d was the highest among all the stabilized sandy soils, and the 28 d immersion stability rate was 72.5%. The 28 d permeability coefficient of sandy soil stabilized by SCCM decreased from 8.7×10⁻⁴ cm/s for natural sandy soil to 5.7×10⁻⁷ cm/s, which was 1–2 orders of magnitude lower than that of SAC and ordinary Portland cement (OPC) stabilized sandy soil. Both scanning electron microscopy (SEM) and X-ray diffraction (XRD) showed the co-existence of ettringite and hydrated calcium silicate gel, and their addition improved the properties of the stabilized sandy soil. The results of the low-field nuclear magnetic resonance (LF-NMR) test revealed that the porosity of the SCCM stabilized sandy soil was lower than that of the SAC stabilized sandy soil and OPC, resulting in a dense structure. This study provides an innovative solution for the utilization of bulk solid waste in stabilizing sandy soil in infrastructure projects.

Graphical abstract