Influence of Curing Time and Initial Moisture Content on Metakaolin-Based Geopolymer-Stabilized Soft Soil

This study thoroughly investigated the impact of initial moisture content and curing time on metakaolin (MK)-based geopolymer stabilized soft soil. The stabilized soft soil was characterized with an unconfined compressive strength test, scanning electron microscopy, energy dispersive X-ray spectroscopy (EDS), and compaction test. The geopolymer was used at different concentrations (5%, 10%, and 15% of the dry weight of the soil), and the soft soil was prepared at its initial moisture content, which ranges from 0.75 LL to 1.25 LL. The results of the test indicate that there was an increase in yield stress at low initial moisture content. Conversely, the yield stress experienced a decrease at high initial moisture content. Furthermore, the strength of geopolymer-stabilized soil increased as the curing time increased, regardless of the binder and initial moisture contents. The microstructure analysis confirmed that the stabilized soil had a denser microstructure, the formation of homogeneous gel, and fewer microcracks and pores. As the automatic compaction test revealed, the maximum dry density increased at higher binder contents while the optimum moisture content decreased. This research demonstrates that stabilizers made with metakaolin can efficiently stabilize soft soils. It is worthwhile to conduct further studies on the durability, shear tests, and cost of using geopolymer for soil stabilization under varying environmental conditions.