Gypseous soils possess unique properties that distinguish them from other soil types, particularly their increased deformation in response to environmental changes, such as wetting and drying cycles. Recently, nano-silica has been utilized as an additive to enhance the geo-technical properties of soils. This study presents a detailed analysis of nano-silica's properties and its effects on reducing dissolved salt content while improving the bonding between particles in gypseous soil with a high gypsum content of 80.4%. The durability of the treatment was evaluated by measuring the unconfined compressive strength, considering factors, such as aging, wetting-drying cycles, and freezing-thawing cycles. The tests were conducted on gypseous-soil samples before and after treatment with several ratios of nano-silica (1, 2, 3, 4, and 5%). The effects of aging were assessed at intervals of 0, 7, 14, 21, and 28 days, while the impacts of wetting-drying and freezing-thawing cycles were evaluated after 0, 1, 3, 6, 12, and 24 cycles. The results demonstrated an increase in soil cohesion with aging, ranging from 33.35% to 57.42%. Adding 1% and 2% nano-silica was insufficient to significantly enhance the geo-technical properties of gypseous soil, whereas 4% and 5% nano-silica yielded comparable improvements. However, soil cohesion decreased with an increasing number of wetting-drying and freezing-thawing cycles, ranging from 6% to 100% and from 15% to 100%, respectively. Keywords: Gypseous soil, Leaching, Nano-silica, Durability, Problematic soil, Geo-technical properties.
Read full abstract