Abstract: The treatment and utilization of substantial quantities of waste dredged silt represent a significant challenge in environmental geotechnical engineering at present. Performance-controlled fluidized solidified backfill (PCFS) is prepared using silt as the soil material and cement as the curing material, with expandable polystyrene (EPS) particles and naphthalene superplasticizer as additives. The variations in density, flowability and strength of PCFS and their regulation method were investigated through a series of tests. The PCFS density decreases with the increase of initial moisture ratio and increases with the increase of cement dosage, but the change is small. The PCFS density changes most obviously with the EPS particles dosage (φ ), and can be reduced to as low as 0.74 g/cm³. The PCFS flowability decreases with the increase of the EPS particles dosage. The ratio of EPS particles volume to PCFS volume increases by 0.3, the PCFS flowability decreases by 15%−20%. The naphthalene superplasticizer admixture significantly enhances the flowability of PCFS, with an improvement rate of nearly 130%. The PCFS strength increases logarithmically with age, increases as a power function with the increase of cement dosage, and decreases linearly with the increase of initial moisture ratio. A power function relationship exists between PCFS strength and EPS particles dosage within the range of 0.3≤φ ≤1.2, with greater sensitivity to EPS particles dosage changes at high cement levels.

Key words: silt, expandable polystyrene(EPS), lightweight soil, flowability, density, strength