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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/3575

Advisors: Prof. Dr.-Ing. Abebe Dinku
Keywords: California Bearing Ratio
Dry Density
Plasticity Index
Soil Stabilization
Copyright: Oct-2011
Date Added: 18-Oct-2012
Abstract: This research work is aimed to evaluate the suitability of slightly alkaline liquid sodium silicate for stabilization of montmorillonitic clay and clayey sand with gravel in Ethiopia. The study is also aimed to investigate the effect of applying sodium silicate in combination with hydrated lime or ordinary Portland cement on the engineering properties of treated soils. The laboratory work involved grain size analysis and index property determination to classify soil samples. Atterberg limit test, Proctor test and California Bearing Ratio tests were used to evaluate properties of treated soils. Montmorillonitic clay was treated using 2%, 4% and 6% lime, 1%, 2.5% and 6% liquid sodium silicate and the respective combinations of the additives by dry weight of the soil. Clayey sand with gravel was treated with 3%, 5% and 7% cement, 1%, 2.5% and 6% liquid sodium silicate and the respective combinations of the additives by dry weight of the soil. Samples were compacted after typical soaking duration of 30 to 45 minutes to account for strength loss due to compaction delay. Samples were typically cured for 3 and 7 days before testing and additional 28 days of curing were considered for Atterberg limit test. Sodium silicate reduced plasticity indexes of samples at least by 11.96% compared to untreated soils. Curing enhanced the reduction in plasticity of soils treated with sodium silicate. It was observed that lime reduced the plasticity index of treated soils; however, carbonation reversed improvements. Atterberg limit samples treated with cement resulted in non- plastic soil. Treating expansive soil with sodium silicate or combination of lime and sodium silicate gave odd curves from which a maximum dry density or optimum moisture content could not be determined. Blending clayey sand with sodium silicate or its respective combination with cement proportionally decreased the dry density of the soil. Sodium silicate or its respective combination with lime gave decreased strength values and increased swelling properties compared to the respective lime treatments. Mixing clayey sand with cement gave significant strength values. Applying 1% sodium silicate in concert with cement gave shear strength values larger than the respective cement treatments. When the quantity of sodium silicate was increased to 2.5% and beyond it hindered strength development. Curing enhanced strength development and reduced swelling properties for all treated soils. Findings imply that good quality materials, dense compaction, proper curing and sufficient stabilizers should be applied for cementitious stabilization. The necessary precautions also need to be taken whenever cementitious stabilizers are applied in combination with sodium silicate so that the soil could be involved in the hydration process. Sodium silicate is not a suitable stabilizer for expansive soils, but it relatively gives encouraging results on course grained materials. Good drainage system is highly recommended for sodium silicate stabilization.
URI: http://hdl.handle.net/123456789/3575
Appears in:Thesis - Civil Engineering

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