Effects of Non-traditional Additives on the Early Strength of a Lean Clay Soil Stabilized by Compound Calcium-based Stabilizer

Soil stabilization is a widely used technique in civil engineering to enhance the engineering properties of fine-grained soils. Traditional calcium-based stabilizers, such as cement, lime (L), and fly ash (FA), are most commonly used due to their availability and proven effectiveness. However, these stabilizers often exhibit slow early strength development. To address this challenge, the present study explores the potential of non-traditional additives to improve early strength in stabilized soils. A range of additives, including two nano-materials, six soluble sodium and calcium salts, five soluble iron and aluminum salts, and cationic polyacrylamide (CPAM), were incorporated into a lean clay soil stabilized with a compound calcium-based stabilizer composed of cement, L, and FA. The 7-day unconfined compressive strength (UCS) was used as the primary performance indicator. The results indicated that within the tested dosage ranges, the two nano-materials, most soluble iron and aluminum salts, and CPAM had minimal or even adverse effects on early strength development. In contrast, specific combinations of soluble sodium salts significantly enhanced early strength. For example, a combination of 0.05% sodium carbonate with 0.05% sodium silicate, and 0.05% sodium sulfate with 0.05% sodium silicate, resulted in strength increases of 34.5% and 33.6%, respectively. Additionally, the standalone addition of 0.5% water glass led to a 32.2% improvement in strength.