Durability of Gypseous Soil Stabilized with Nano-silica under Environmental Conditions

Abstract

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.