Experimental study on performance of waste slag based geopolymer stabilized silt clay

It is extremely urgent to implement comprehensive resource utilization within the framework of the dual carbon strategy. To improve the mechanical strength properties of silty clay, three types of industrial waste slag, such as slag, bottom ash and gypsum, are utilized as primary raw materials. A waste slag-based geopolymer is then prepared through synergistic activation in an alkaline quicklime environment to stabilize the silty clay and enhance its engineering characteristics. The deformation characteristics of samples under varying waste residue geopolymer content were analyzed through unconfined compressive strength tests and X-ray diffraction (XRD) microscopic tests. The study compared and examined the influence of curing method, fiber addition, and curing age on sample performance, as well as explored the types of hydration products present. A test section of waste residue geopolymer-stabilized silty clay base was constructed for the actual project. The key findings suggest that the optimal dosage of waste slag geopolymer-stabilized silt clay is 15%, with a slag: bottom ash: quicklime: gypsum mix ratio of 8:2:3:2, polypropylene fiber content of 0.2%, and a curing method of 6 d standard curing followed by 1 d of soaking. The mechanical properties of the samples show significant improvement, particularly in the toughness region of the stress-strain curve due to fiber reinforcement. The samples exhibit excellent water stability, and extending the immersion curing age appropriately enhances the sample's strength, with a water stability coefficient reaching up to 200% The fibers, waste residue geopolymer hydration gel and soil particles interlock closely to create a dense three-dimensional network structure, thereby enhancing the mechanical strength of the fiber-hydration gel component-soil particle interface. The curing time significantly impacts the sample, with a strength growth rate ranging from 80% to 188% at 28 d.