Investigation into the Enhancement Characteristics of Fly Ash and Polypropylene Fibers on Calcium Carbide-Residue-Stabilized Soil

The recycling and reuse of waste materials is an important part of promoting sustainable development. Encouraged by cleaner production and a circular economy, the introduction of calcium carbide residue (CCR) for the stabilization of soil foundations has become a hot topic in the road engineering industry. Aiming at the efficient application of CCR-stabilized soils, the optimization of the material composition was focused on in this work. Fly ash and polypropylene fibers were introduced into the preparation of CCR-stabilized soils, and their effects on the mechanical properties and water stability were tested. The findings highlight that the strength of fly-ash–carbide-residue-stabilized soil was higher than that of carbide-residue-stabilized soil at the same curing age. Furthermore, the unconfined compressive strength, splitting strength, and water stability of CCR–fly-ash-composite-stabilized soil initially increased and then decreased with a rise in polypropylene fiber content. The peak values of confining compressive and splitting strength were observed when the polypropylene fiber content was 1.2‰, while the water stability coefficient A reached its peak value at 0.8‰. From the standpoint of the comprehensive performance improvement and economy of composite-stabilized soil, it is advised that the dosage of polypropylene fibers falls within the range of 0.8–1.2‰. The engineering technical indexes of polypropylene-fiber–CCR-composite-stabilized soil fulfilled the requirements of the specification and had a satisfactory effect on delaying the cracking of the specimen. It is expected that this investigation will provide support for the resource utilization of CCR and the sustainable development of road construction.