Silty soils containing sodium content, known as salty silty soils, are classified as another type of problematic soil. When this type of soil comes into contact with water, it can swell and diverge, leading to settlement and deformation. Considering that a significant part of the Urmia Lake basin and the Tabriz plain consists of sodium-rich fine soils, the aim of the project is to improve the quality of the soils. Therefore, one of the main objectives of this study is to assess the sediments within the lake bed in order to reduce erosion and to evaluate the possibility of improving and stabilizing the sodium saline silty soils in the area using the geopolymerization technique. To achieve this, pumice material with pozzolanic properties was separately mixed with the soil under investigation at weight percentages of 3%, 5% and 7%, together with a calcium hydroxide solution as a catalyst at concentrations of 2%, 5% and 7%. The samples were then cured for one day. Laboratory tests, including compaction, uniaxial compressive strength, direct shear, and consolidation, were carried out to evaluate the geotechnical behavior of the improved soil. The results obtained indicate that the combination of 3% pumice with 2% calcium hydroxide increased the uniaxial compressive strength of the stabilized sample by 1.32 times after one day of curing. In addition, the mixture of 7% pumice with 2% calcium hydroxide significantly improved the internal friction angle by 20 times. Finally, the combination of 7% pumice with 2% calcium hydroxide reduced the value of free swelling potential by up to 86%.
