Synergistic stabilization of expansive soil using ground granulated blast furnace slag, fly ash, and waste tire textile fibers: mechanical properties and micro-mechanisms

The stabilization treatment of expansive soil and the resource utilization of industrial solid waste are two prominent research areas in geotechnical engineering. The utilization of industrial solid waste to solidify expansive soil offers both economic and environmental benefits. This study employs ground granulated blast furnace slag, fly ash, and waste tire textile fibers to synergistically expansive soil. Through swelling strain tests, unconfined compressive strength tests, California bearing ratio tests, X-ray diffraction analysis, and scanning electron microscopy analysis, the systematic investigation was conducted on the effects of binder dosage, ground granulated blast furnace slag/fly ash ratio, and waste tire textile fiber content on the performance of expansive soil. The results show that when the binder dosage is 15%, the ground granulated blast furnace slag/fly ash ratio is 8:2, and the waste tire textile fiber content is 0.7%, the proposed solidified expansive soil achieves optimal mechanical properties. Compared to untreated expansive soil, the unconfined compressive strength at curing ages of 7, 14, and 28 days increases by more than fivefold. The California bearing ratio of the stabilized soil reaches a maximum value of 25.22%, representing a substantial improvement over the untreated expansive soil, with a California bearing ratio of only 3.16%. X-ray diffraction and scanning electron microscopy analyses confirmed the reinforcing effects of the binder and waste tire textile fibers in the stabilized soil. The proposed method for stabilizing expansive soil not only enhances its engineering performance but also facilitates the resource utilization of waste tire textile fibers—a type of solid waste with extremely low utilization rates—thereby demonstrating substantial potential for widespread adoption and application.