Critical Assesment on the Stabilization Of Expansive Soils by Different Techniques

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Addis Ababa University


The evaluation and criticism of the stabilization of expansive soil by different techniques base on the researches done. To list them:- 1. A Research on “Stabilization of expansive clay soil with sugar cane molasses and cement” for the Study Area of Modjo – Ejere – Arerti – Sembo Road Project with different mix ratios and come up with a finding that Soil treated with cement and molasses combination gave a significant improvement in strength than when cement and molasses alone and meaningfully reduced swelling property of the expansive soil. Also it was effective in arresting linear shrinkages and eliminated shrinkage cracks that were observed in soil treated with cement alone. 2. A research on “Stabilization of Expansive clay soil with lime “ for the Study Area Adura-Burbey Road project, Gambella and come up with a finding that expansive Soil treated with the addition of lime alone gave a reduction of the free swell, reduction in plasticity limit; improve the CBR, increase of the unconfined compressive strength. 3. A research on “The chemical treatment of “Block Cotton” soil to make it usable as a foundation material”for the study area of ten samples from Addis Ababa ‘’Black –cotton’’ soils and come up with a finding that the geotechnical property these expansive soils have been improved from a vary high expansive to a moderate expansive soils by the addition of 6% lime and 12% cement independently by dry weight of the native soil. 4. A researcher on “Evaluation of Sodium Silicate and its Combination with Cement/Lime for soil stabilization” for the study area of in situ soil of Addis Ababa’s Bole Senior Secondary and Preparatory School and borrowed material from Gergi-Bole Road section and has come up with the finding that Sodium Silicat has an inhibiting effect on strength development of clayey sand soil-cement mixture when its quantity is increased to and beyond 2.5% by dry weight of the soil. But Applying lower amount like 1% sodium silicate AAiT School of Graduate Studies by dry weight of the soil in concert with ordinary Portland cement is used it has positive implications on strength development .But using Sodium silicate as chemical stabilization with or without lime is not a suitable additive for montmorillonitic clay (expansive soil) stabilization. 5. A researcher on “Bagasse Ash as a Sub-grade Soil Stabilizing Material” for the Study Area of Addis Ababa, Bole Sub City around Bole Medhanialem church and come up with a finding that While treating expansive soil, with an increase in the bagass ash addition alone, there is a decrease in free swell, free swell index and free swell ratio but it is with a slight decrease in the plasticity and a slight increase in the CBR value. But the addition of bagasse ash in combination with lime improved the CBR value, and plasticity index decreased significantly. So, from critically evaluating these, the lime content increase the PI ratio, Free swell ratio and CBR swell ratio all shows increasing, indicating that the PI, the free swell and the CBR swell values are all decreasing in a direct proportion. In addition, in case of the free swell ratio verses the lime content it can be approximated that all the graphs do overlap one over the other meaning the testing procedures and the precision during the testing are approximated to be equal. Yet, a more different scenario is observed during the CBR swell tests verse the lime content this may arise due to the soil sample preparation and testing procedures. Another evaluation is as the cement content increase the PI ratio shows increasing indicating that the PI values are decreasing .In addition ,it can be seen that the PI ratio gets flat beyond some 6% to 12% cement addition indicating that further addition do not have an significant impact on the PI value. Key Words: Cement, lime, Sodium silicate, Bagass Ash, Expansive Clay Soil, Sugar Cane Molasses, Soil Modification, Soil Stabilization. Critical Review



Key Words: Cement ;lime; Sodium silicate; Bagass Ash; Expansive Clay Soil; Sugar Cane Molasses;Soil Modification ;Soil Stabilization; Critical Review