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Stabilization of expansive soils by using red mud

Çağlar, Cemre
Expansive soils are generally existing in semi-arid and arid regions of the world. This type of soils expands when they absorb water and shrink when they dry out. Expansive soils are causing problems to the lightweight structures. The purpose of the study is to suggest a cost-effective alternative method for coping with these problems. The widely used traditional method is the stabilization of the soil with the chemical admixtures. In this study; waste red mud and waste fly ash were used as stabilizers. The expansive soil is prepared in the laboratory conditions, as a mixture of the kaolinite and bentonite. In the previous studies; fly ash, lime and cement are used for improving the swelling and strength properties of the soil. This study examines the effect of red mud as a stabilization material for soil. The admixtures were added to the soil in different percentages and separately to compare the effect of the admixtures. Grain size distributions, consistency limits, swelling percentage, rate of swell, uniaxial compressive strengths, direct and split tensile strengths of the samples were determined. Specimens were evaluated by their swelling percentages, swelling rates, undrained shear strengths and tensile strengths. These criteria show the effectiveness of the stabilizers. The results of the study prove that undrained shear strength is increased to 4 times of Sample A’s value, while swelling potential decreased to 1/3 times and rates decreased 1/4 times of it, with addition of red mud, fly ash and cement.