Gypseous soils present significant geotechnical challenges due to their highly variable and moisture-sensitive behavior. Although often considered mechanically stable in dry conditions, these soils are susceptible to sudden volumetric collapse upon wetting, leading to severe structural and infrastructural damage. This study evaluates the potential of nanomaterials specifically nano-clay and nano-metakaolin as stabilizing agents to mitigate the collapse susceptibility of gypseous soils. Representative soil samples, containing approximately 54% gypsum, were collected from Tikrit, Iraq, located about 200 km north of Baghdad. The experimental program involved preparing soil specimens treated with three nanomaterial contents (1%, 2%, and 3% by dry weight) and subjecting them to collapse potential and compressibility tests under both dry and soaked conditions. The results indicated that the inclusion of nanomaterials substantially decreased collapse potential and compressibility, with improvements becoming most significant at contents above 2%. At 3% incorporation, settlement was reduced by 40–60% before soaking and by 25–40% after soaking. These findings demonstrate that nanomaterials, particularly at higher dosages, enhance soil stability by reducing susceptibility to collapse and deformation. The study highlights the effectiveness of nanotechnology-based additives as a sustainable and innovative solution for stabilizing problematic gypseous soils in arid and semi-arid regions.
