Browsing by Author "Demissu, Brook"

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    Influence of Molding Water Content on the Engineering Properties of Lime Stabilized Expansive Soil
    (Addis Ababa University, 2015-09) Demissu, Brook; Tadesse, Samuel (PhD)
    Expansive soil is considered defective due to the large volume change it undergoes for any moisture fluctuation. There are several engineering solutions to the problems these soils pose to the structures built on them. At times when removing the defective soil is uneconomical or impractical, stabilizing the soil with lime has proven to be effective. Past researches on lime stabilization of expansive soils identified many factors influencing the stabilization process. However, all the factors that contribute to best results are not yet obtained. Common practice in lime stabilization is to compact the mixture of soil and lime at optimum moisture content (moisture content at maximum dry density). If the soil is expansive, at maximum dry density, large amount of expansive clay minerals (montmorillonite) will fill a given volume. On the other hand, using the dry side of the optimum moisture content may affect water dependent reactions that takes place during lime stabilization. If one uses the wet side of the optimum moisture content to mix the soil with lime, the clay mineral will absorb more water and go through large volume change. Therefore, the optimum amount of water required for lime stabilization of an expansive soil must be determined through laboratory experiments. This research tends to identify the properties of an expansive soil. Lime is then added in proportions of 0%, 2%, 4%, and 6% to the soil sample. After a series of laboratory tests the optimum amount of lime that obtains desirable effect on engineering properties of the soil is determined to be 6%. Then, the stabilized soil property at the wet and dry side of the optimum moisture content has been investigated. The results of the research have shown that molding water content does not affect the swelling pressure. However, unconfined compressive strength improves significantly on soil specimens ix prepared on the wet side of optimum moisture content of soil-lime mixture. The improvement in compressive strength on the wet side of optimum moisture content is found to be dependent on the curing time.