Improvement of Gypsiferous Soil Strength by Silicone Oil

Abstract

Gypsiferous soils are usually stiff when dry, mainly because of the cementation of soil particles by gypsum. However, significant loss in strength and sudden increase in compressibility can occur when these soils are fully or partially saturated, and the dissolution of the cementing gypsum causes a high degree of softening of such soils. The problem becomes more complex when water flows through gypsiferous soil, causing leaching and movement of gypsum. This study examines the improvement of gypsiferous soil properties by using silicone oil to minimize the effects of moisture and gypsum loss. The work was conducted on artificial gypsiferous soil (30% Silber sand and 70% pure gypsum) treated with silicone oil in different percentages. Silicone oil was selected as an additive because of leakages of oil-related products from an oil refinery north of Iraq built on gypsiferous soil. Thus, this oil product provides a suitable analogue for that which has infiltrated the foundation soil of the refinery buildings. The results show that the silicone oil is a suitable material for modifying the basic properties of the gypsiferous soil, such as collapsibility and shear strength.