Optimization and mechanism of nanomaterial-modified alkali-activated binders for stabilizing waste marine clay: A Taguchi approach incorporating curing temperature effects

Waste marine clay, characterized by high water content, high compressibility, and low bearing capacity, remains unsuitable for road construction even after pretreatment and requires further improvement with soil stabilizers. Conventional ordinary Portland cement (OPC) or lime stabilization suffers from environmental drawbacks and poor low-temperature performance, while traditional alkali-activated binders (slag–Ca(OH)₂ systems) exhibit limited early-age effectiveness and long-term reliability. This study investigates the influence of nano-SiO₂, nano-CaCO₃, and nano-Al₂O₃ on the mechanical and microstructural properties of alkali-activated binders (AAB) for stabilizing pretreated marine clay. Using the Taguchi method, the mix proportions of nano-modified AAB (N-AAB) were optimized. Results show that the optimized N-AAB significantly enhances soil mechanical performance, achieving UCS values of 2.773 MPa and 7.103 MPa after 7 and 60 days of standard curing, and 2.681 MPa (7 days) and 6.764 MPa (60 days) under low-temperature curing—demonstrating excellent strength retention. The N-AAB stabilized soil outperformed OPC-stabilized soil in both low-temperature resistance and long-term strength development. Microstructural and mineralogical analyses revealed that low-temperature curing promotes unique hydration products and microstructures in N-AAB stabilized soil. Hydrates such as AFm phases and C-(A-)S-H gels improve the soil matrix through morphological and quantitative advantages, contributing to enhanced strength. This study establishes a feasible approach for integrating nanomaterials into soil stabilization and supports the sustainable reuse of waste marine clay in road construction.