Stabilization Performance and Mechanism of the Gravelly Soil Stabilizer Prepared from Waste Foam Concrete

Gravelly soil is widely distributed in the central and western regions of China and serves as a crucial fill material for transportation infrastructure. However, its poor gradation, poor water stability, and low freeze - thaw resistance limit its direct application. To address the problems of high energy consumption and high carbon emissions of existing solidifying agents (such as cement, lime) and achieve the resource utilization of waste foam concrete, this study took waste foam concrete as the raw material, prepared a novel gravel soil stabilizer through crushing, ball milling, and high - temperature calcination, and systematically studied the solidification performance (unconfined compressive strength, water stability, freeze - thaw resistance) of the prepared stabilizer on gravelly soil and its solidification mechanism. The results show that the prepared stabilizer can significantly improve the mechanical properties of gravelly soil. At a dosage of 30%, the unconfined compressive strength reached 6.5 MPa after 28 days, an increase of 333% compared to the control group. The water stability is enhanced with the increase of dosage, and the water stability coefficient is significantly improved at a dosage of 30%. In terms of freeze - thaw resistance, at a dosage of 30%, the mass loss rate was only 2% after 5 freeze - thaw cycles, and the unconfined compressive strength reached 9.56 MPa, an increase of 437% compared to the control group. XRD and SEM analysis indicate that the stabilizer generates cementitious products such as calcium silicate hydrate gel and katoite through hydration reactions, which fill the pores of gravelly soil, cement particles, and optimize the microstructure, thereby improving its mechanical properties, water stability, and freeze - thaw resistance. This study provides a new way for the efficient resource utilization of waste foam concrete and also offers a low - energy and environmentally friendly novel stabilizer for the reinforcement of gravel soil subgrades in cold regions.