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

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.

传统钙基稳定剂（如石灰）用于加固富硫酸盐膨胀土，长期以来都是岩土工程领域的技术难题。钙基稳定剂应用的核心弊端在于：当钙组分与水共同作用于富硫酸盐膨胀土时，会生成膨胀性矿物钙矾石（ettringite），进而引发硫酸盐诱发的土体隆起。本研究旨在探究采用地质聚合物（geopolymers）加固富硫酸盐膨胀土以适配交通基础设施建设的可行性。针对硫酸盐诱发土体隆起及地质聚合物加固富硫酸盐膨胀土的现有文献综述，为采用地质聚合物加固硫酸盐土的技术路径指明了方向。本研究开展了系列土工试验，以测定原状土、石灰加固土及地质聚合物加固土的胀缩特性与强度性能。此外，通过配备能量色散X射线能谱仪（EDS）的扫描电子显微镜（SEM）及X射线衍射仪（XRD）测试，对比分析了地质聚合物加固土、原状土与石灰加固土的微观结构变化。为深入探究地质聚合物对富硫酸盐膨胀土的加固效果，本研究通过室内试验系统考察了地质聚合物配比、掺量及养护龄期对加固效果的影响。