EXPERIMENTAL INVESTIGATION ON STABILIZATION OF EXPANSIVE SOIL BY FIBER-REINFORCED ALKALI-ACTIVATED INDUSTRIAL WASTE-BASED GEOPOLYMER BINDER

This study aims to examine the coupling effect of industrial waste ash and Basalt fiber (BF) to improve the mechanical properties of the expansive soil. A series of geotechnical and electron microscopic tests were carried out to analyze the type of geopolymer admixture, effects of alkali activator (AA), and fiber admixture on the mechanical properties of expansive soils. The unconfined compression tests (UCT) were performed to optimize the material ratio of alkali-activated binder (AAB)-treated expansive soil (ES) and explore the optimum content of basalt fiber (BF) in AAB-treated ES. The results showed that: The unconfined compressive strength(UCS) of industrial waste-based geopolymer modified soil increased and the optimal content is 20%.The method with better improvement effect is the soil used Ground-Granulated Blast Furnace Slag and fly ash (GGBS-FA) as a geopolymer after alkali activated.BF can improve the strength of the modified soil and exhibit better toughness. With the ratios of fiber increasing, the strength of the modified soil shows a trend of increasing firstly and then decreasing, and the optimal fiber content was 0.6%; It was found by electron microscope that the mechanical characteristics of soil changed in that the orientation of structural units and the fractal dimension of particles were enhanced. In conclusion, the industrial waste-based geopolymer with fiber-reinforced has strong potential as a lower-carbon-footprint alternative to conventional stabilizers for expansive soils.