Strength development and solidification mechanism of soils with different properties stabilized by cement-slag-based materials

Soil stabilization involves modifying the physical and chemical properties of soil to enhance its engineering performance for construction purposes. Due to inherent variations in these properties, the mechanical characteristics of stabilized soils can differ significantly across regions. This study utilized Portland cement and self-made cement-slag-based binders to improve soil engineering properties. Through comprehensive physical, chemical, and microscopic experiments, the differences in strength between acidic high-plastic liquid-limited clay and alkaline low-plastic liquid-limited coarse-grained soil, the optimal Ca(OH) 2 dosage, and the mechanisms behind strength development in solidified soil were examined. The results indicate that the strength of solidified soil primarily arises from cementation between soil particles and the filling of expansive products. Cementation forms the basis for strength generation, while filling is essential for further strength development. Factors such as soil pH, clay content, and cation adsorption capacity significantly influence the hydration products of cementitious materials, leading to marked differences in soil strength. Increasing the content of Ca(OH)₂ can promote the formation of calcium hydroxide silicate and hydrated gypsum, enhancing particle cohesion and reducing pores larger than 1 μm, thereby achieving a maximum 28-day strength of 6.4 MPa. Optimal Ca(OH) 2 content was found to be 9 % for clay and 3 % for sandy soil. Excess Ca(OH) 2 can create additional interfacial transition zones, affecting overall soil stability. These findings elucidate the reasons behind strength variations in solidified soils with different properties and offer valuable insights for practical applications in construction and geotechnical engineering.