This research explores the stabilization of clay soil through the application of geopolymer binder derived from silicomanganese slag (SiMnS) and activated by sodium hydroxide (NaOH). This research aims to evaluate the effects of key parameters, including the percentage of slag, the activator-to-stabilizer ratio, and curing conditions (time and temperature), on the mechanical properties of the stabilized soil. Unconfined compressive strength (UCS) tests were conducted to assess improvements in soil strength, while scanning electron microscopy (SEM) was employed to analyze the microstructural changes and stabilization mechanisms. The results demonstrated that clay soil stabilized with SiMnS-based geopolymers exhibited significant strength enhancement. Specifically, the sample stabilized with 20% SiMnS and an activator-to-slag ratio of 1.6, cured at room temperature for 90 days, achieved a UCS of 27.03 kg & frasl;cm2. The uniaxial strength was found to be positively correlated with the SiMnS content, activator ratio, curing time, and temperature. Additionally, the strain at failure remained below 1.5% for all samples, indicating a marked improvement in soil stiffness. SEM analysis revealed that geopolymerization led to the formation of a dense matrix, enhancing soil particle bonding and overall durability. These results emphasize the potential of SiMnS-based geopolymers as a sustainable and effective soil stabilizer for geotechnical applications.

The freeze-thaw damage of cementitious coarse grained fillings (CCGFs) significantly affects the firmness, stability, and durability of high-speed railway subgrades. It is favorable to employ geopolymer binders to improve the engineering performance of coarse grained fillings (CGFs), further ensure the safety of high-speed railway subgrades in cold regions due to their excellent mechanical and environmental-friendly performances. This study conducted a series of freeze-thaw and mechanical tests on geopolymer stabilized coarse grained fillings (GSCGFs). The influence of gradation, compaction degree, and freeze-thaw cycles on the integrity, strength, and stiffness of GSCGFs was investigated. The evolution law of their freeze-thaw damage was discussed quantitatively based on an improved damage factor. The results show that the mass loss rate of Group B GSCGFs with a fine-grained particle content of less than 15% was lower than that of Group A GSCGFs with a fine particle content between 15% and 30% overall. When other conditions remain unchanged, the mass loss rate of GSCGFs decreased with the increase of compaction degree but increased nonlinearly with the freeze-thaw cycles. The strength and stiffness of GSCGFs decrease nonlinearly with the freeze-thaw cycles and presented a first fast and then slow-down change trend, their stiffness evolution at different compaction degrees revealed a big difference due to the weakening bite effect and enhancing overhead structure among rock blocks. The strength reduction of Group A GSCGFs was less than that of Group B under the high compaction degree. The stiffness deterioration of Group A GSCGFs was about twice that of Group B. There seemed to be no absolute correlation that the strength of GSCGFs was positively correlated with their stiffness. By building an exponential relationship between the compressive strength of GSCGFs and the freeze-thaw cycles that followed the findings of previous several studies, an improved exponential damage evaluation model was proposed to represent the performance degradation of GSCGFs. The outcomes of this study can provide theoretical support for understanding the physical and mechanical behaviors of GSCGFs and applying them in engineering practices.