Abstract: Portland cement is the most widely used material for soil stabilization. However, its extensive application leads to substantial energy consumption and increased soil alkalinity. To address these issues, this study introduced a silicon-containing additive to cement-stabilized soil with the aim of enhancing soil strength and reducing pH levels. The effects of cement content, silicon-containing additive dosage, and curing age on unconfined compressive strength and pH value were investigated through unconfined compression tests and pH measurements. The results demonstrate that the silicon-containing additive reacts with Ca (OH)₂ produced during cement hydration, promoting further hydration reactions and generating additional cementitious materials that fill soil pores. This process enhances soil strength while consuming Ca (OH)₂ to reduce soil pH. With 3% silicon-containing additive, the strength of cement-stabilized soil increased approximately fourfold, while the pH decreased to a minimum value around 10. Furthermore, 2% silicon-containing additive could replace 5% cement while achieving equivalent strength. These findings indicate that silicon-containing additives not only significantly improve the strength of cement-stabilized soil but also effectively reduce its pH value, thereby minimizing environmental impact. This approach demonstrates considerable value for engineering applications.