Eco-friendly stabilization of sulfate-rich expansive soils using Geopolymers for transportation infrastructure

Traditional calcium-based stabilizers, such as lime, to stabilize sulfate-rich expansive soils, are lasting-challenges in geotechnical engineering. The biggest problem with using calcium-based stabilizers is that when calcium and water are exposed to sulfate-rich expansive soils, they form ettringite as an expansive mineral, which causes sulfate-induced heaving. The study aimed to investigate the feasibility of stabilizing sulfate-rich expansive soils using geopolymers for transportation infrastructure. Literature review on sulfate-induced heaving and sulfate-rich soils stabilized with geopolymers suggests a direction for how to stabilize sulfate soils using geopolymers. The engineering tests were conducted to determine the swell, shrinkage, and strength behavior of natural, lime stabilized- and geopolymer-stabilized soils. Scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) and X-ray diffractometer (XRD) tests were performed to compare the microstructural changes of geopolymer-stabilized soils with natural and lime-stabilized soils. Laboratory tests were conducted considering the influence of the geopolymer composition, dosage, and curing period to investigate the effect of the geopolymer in stabilizing the sulfate-rich expansive soils.