Abstract:

Gypseous soils are considered problematic soils because the soil cavities happen during receiving the water or this type of soil and solving gypsum materials and contract in a soil volume. In this study, three types of gypseous soils are used; soil1, soil2, and soil3 with gypsum content (28.71%, 43.6%, and 54.88%) respectively, petroleum products (engine oil, fuel oil, and kerosene) are added to the soils with percentages (3%, 6%, 9%, and 12%) for each product. The result showed that specific gravity, liquid limit, optimum moisture content (O.M.C), and maximum dry density decreased with an increased percentage of product for all types of products. The direct shear (dry and soaked case) results show that increasing the (angle of internal friction and the soil cohesion) for soil1, soil2, and soil3 by adding engine oil and fuel oil. Still, when the soils were treated with kerosene, the angle of internal friction increased while cohesion decreased. The collapse potential for the treated soils increases with increasing gypsum content for all petroleum products. The collapse potential (CP) for (soil1) decreased by 47% when using 6% of the engine oil, 48.8% when using 9% of the fuel oil, and 55% when using 9% of the kerosene. The same percentage of the petroleum products (engine oil, fuel oil, and kerosene) decrease the collapse potential for (soil2), (47%, 46%, and 50%) respectively and decrease the collapse potential for (soil 3), (51%, 47.7%, and 52%) respectively. In the unconfined compressive test applied on (soil1) using maximum density, the results show that the soil strength increased (26% and 10%) when using 6% and engine oil and fuel oil, respectively, while the soil strength decreased by 29% when treated with 9% of kerosene.

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