Strengthening Gypsum Soils: The Role of Lime and CaCO3 Nanoparticles in Enhancing Suction and Compressive Strength

Abstract

This study examines the characteristics and stabilization of two types of gypsum soils, known for their high gypsum content, which affects their physical and chemical properties. Gypsum soils pose challenges in construction due to their solubility in water, leading to instability. The research focuses on the interaction of moisture content, gypsum concentration, and soil structure under different climatic conditions.
The study evaluates the relationship between soil total suction, measured by the filter paper approach, and unconfined compressive strength in both natural and processed gypsum soils. Stabilization techniques using CaCO3 and lime nanoparticles (NPs) were explored. The connection between compressive strength and total suction was established through the degree of saturation obtained from the soil water characteristic curve and optimal water content.
Results showed that for SG50 soil, the maximum compressive strength increased with treatment ratios up to (L3% + N1%), which had the highest strength. Beyond this ratio, slight fluctuations were observed, while total suction continued to decrease. This is likely due to nanoparticle agglomeration at excessive treatment levels, reducing soil cohesion. In SG2% soil, compressive strength showed fluctuations, initially increasing, then decreasing until stabilization, while total suction was consistently reduced. The lower suction values in SG2% soil compared to SG50% are attributed to its lower gypsum content, which reduces chemical reactions with water and the formation of suction-enhancing compounds.