Laboratory Evaluation of the Engineering Properties of Fluidized Solidified Soil Prepared with Multisource Solid Waste for Municipal Backfill Engineering

The resource utilization and high-value application of bulk solid waste, tailored to local conditions in the field of backfilling engineering, is a crucial strategy for promoting low-carbon development in municipal engineering. To enhance the resource application of solid waste materials in municipal backfilling engineering, a multisource solid waste–based fluidized solidified soil is developed in this study using silt soil, cement, blast furnace slag, calcium carbide slag, and gypsum. The workability and mechanical properties of fluidized solidified soil are thoroughly investigated. The segregation characteristics, dry shrinkage deformation, and settlement variations of fluidized solidified soil prepared with varying mud moisture content and curing agent concentrations are assessed, revealing the stability formation mechanism of fluidized solidified soil. The results indicate that when the curing agent content is below 16%, the fluidized solidified soil exhibits excellent workability. The 7-day unconfined compressive strength of fluidized solidified soil ranges from 0.61 to 1.7 MPa. An increase in mud moisture content adversely affects the stability of the fluidized solidified soil, whereas an increase in curing agent content significantly improves its properties. Based on the workability, mechanical properties, and stability of fluidized solidified soil, the recommended mud moisture content is between 79% and 85%, while the curing agent content should be between 12% and 16%. The formation of hydration products within the fluidized solidified soil, such as C–S–H gel and ettringite, contributes positively to the stability of backfilling engineering.