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Title: ChemicalStabilizationofExpansiveSub-gradeSoilPerformanceEvaluationonaSelectedRoadSectioninNortheasternAddisAbaba
Authors: Habtamu, Solomon
Advisors: TarunKumarRaghuvanshi(Dr.)
Keywords: ChemicalStabilization
Copyright: Mar-2011
Date Added: 24-Jul-2012
Publisher: Addis Ababa University
Abstract: Expansive soils are characterized by volume change due to variation in moisture content. The cyclic wetting and drying processes causes vertical movements in expansive soils and these movements lead to failure of pavements. These soils have very low load bearing capacity too when wet. These problematic expansive soils,therefore,when encountered a ssub-grades hould be avoided or treated properly. Theremoval of expansive soils and replacement with suitable fill material is an appropriate method in areas like AddisAbaba in most cases where there suitable fill material available nearby. At places,however,its feasibility depends on the availability of suitable fill material with in economic distances and the thickness of the poor sub- grades oil to be replaced. Chemical stabilization is another alternative being applied worldwide evenif the method is at a conceiving stage in Ethiopia. In recent years there are tendencies to use lime and other chemicals to stabilize sub-grade and sub base materials by Ethiopian Road Authority (ERA) and Addis Ababa City Roads Authority(AACRA). In the present study,hence,the performance of a locally manufactured hydrated lime and an imported industry product Any way Natural Soil Stabilizer(ANSS) were evaluated based on laboratory test results on expansive sub-grade soils collected fromGerjiarea.The sub-grade soil was first characterized based on Atterberglimits, linear shrinkage,CBR and percentswellofCBR.The test results showed that the sub-grade soilis class if idea sA-7-5 in the AASHTO and MH in USCS systems.These soils have very low load bearing capacity and are highly expansive nevertheless so fthemineralogy of the sub-grade soils amples have nomontimorillonite,as expected in such soils. Two soil layers on colour variations were observed in the field: the upper dark gray clay soil and the lower light gray clay soil. The effects of the chemicals were then evaluated on two soil samples. The improvement of the sub- grade soil samples increased with increasing both dosages as well as curing periods. Ingeneral terms,increasing the dosage has more significant effect than that of in creasing the curing period and 4% of either chemical has resulted in adequate improvements of the sub-grade soil.In most cases the performance of hydrated lime is better than that of ANSS and the improvement of the dark gray clay soil is better than the light gray clayil.
Description: A thesis submitted to school of graduate studies of Addis Ababa University in partial fulfillment of the requirements for the Degree Of Master of Science in Engineering Geology.
URI: http://hdl.handle.net/123456789/3472
Appears in:Thesis - Earth Sciences

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