Objective To address the contradiction between the large accumulation of excavated soil generated during engineering construction and the scarcity of subgrade fill materials, it is necessary to investigate the feasibility of in-situ improvement and resource utilization of excavated soil as subgrade fill, and to comprehensively evaluate its mechanical properties, water stability and economic efficiency.

Method A solid waste-based stabilization materials （SWM） is prepared using carbide slag, desulfurization gypsum, and fly ash, with quicklime used for comparison. Through compaction tests, unconfined compressive strength （UCS） test, and water stability tests, the effects of the two stabilizers on the stabilization performance of excavated soil are systematically analyzed, and their economic benefits are compared.

Result & Conclusion  The results indicate that the performance and economic efficiency of SWM-stabilized excavated soil are significantly superior to those of quicklime. Under a dosage of 7% and a curing period of 28 days, the UCS of SWM-stabilized soil reached 0.76 MPa, representing a 41% increase compared with lime-stabilized soil, and the water stability coefficient is 0.82. All indicators meet the specification requirements for subgrade fill. In addition, SWM demonstrates better economic efficiency. This study provides a new type of stabilization material for the large-scale disposal and resource utilization of engineering excavated soil.