DIYALA JOURNAL OF ENGINEERING SCIENCES

Abstract

One of the effected problems that the civil engineer faces it in construction of buildings is the presence of gypseous soils. Gypseous soil is highly dissolved when its water content increases. There are many treatments for such soils like soil replacement, earth reinforcement, compaction, addition of asphalt, lime, fuel oil and other.
In this study, the improvement properties of gypseous soils were investigated using fuel oil which is one of a little cost materials and because of the ability of this material to prevent the water action and to distribute in voids of soil. Gypseous soils used in this study, which contain (49.4%) gypsum content, were brought from Tikrit city, Salah-Aldeen governorate. The addition of fuel oil to gypseous soil, was with different percentages (0, 2, 4, 6, 8 and 10%) to get more observation about the study.
The results showed that the maximum dry density decreases while the optimum moisture content increases with increasing fuel oil content. Moreover, this study showed that as the fuel oil content increased to an optimum value (8%), the maximum unconfined compressive strength, the cohesion (c) and the angle of internal friction (φ) increased to about (34%), (52%), (15%) respectively, then decreased. When the treated and untreated samples soaked in water, the maximum unconfined compressive strength, the cohesion (c) and the angle of internal friction (φ) decreased to about (37%), (21%), (12%) respectively, at an optimum fuel oil content (8%). The initial void ratio (e_0) and collapse potential (C.p.) decreased to about (32%), (90%) respectively, as the fuel oil content increased to an optimum value (8%). The compression index decreased as the fuel oil content increased to an optimum value (8%) then increased.
The main results indicated that using fuel oil (8% fuel oil content) provides better solution for problems of gypseous soil. Using this material improving the engineering properties of the gypseous soils and reducing the collapsibility, especially when these soils faced the wet condition.