The Study of Alternative Chemical Stabilization of Clays with Agricultural Waste Materials for Rural Housing

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Date
2012
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Abstract
The stabilization of clay for improved structural properties was investigated using the Afari and Mfensi clays. Geotechnical chemical and phase analytical methods were used to characterize both the raw and treated clays. For stabilization, lime, cocoa pod husk ash (CPA) and oil palm empty bunch ash (PBA) were used. The linear and volumetric drying shrinkages, dry and wet compressive strength and water absorption of the samples were investigated. Some of the samples were kept in the open for two years for durability test. Results showed that plasticity, percentage linear and volumetric drying shrinkages were reduced on the addition of the additives. There was an increase in compressive strength of the treated samples with lime, CPA and PBA as additives. Among these three stabilizers tested, the lime plus CPA and lime plus PBA showed good durability behaviour. A maximum compressive strength of 5.85 N/mm2 was obtained from treated test pieces made with Mfensi clay (75%) plus lime (10%) and CPA (15%). Minimum water absorption values of 27.75% and 17.78% were also obtained for the treated test pieces made with Afari clay (70%) plus lime (15%) and CPA (15%) and Mfensi clay (65%) plus lime (15%) and CPA (20%) respectively. Test pieces treated with the lime plus CPA and lime plus PBA as additives did not disintegrate after 28-day of soaking in water. XRD analysis showed that improvement in structural properties of the clays was due to the conversion of part of lime to calcium carbonate (Calcite, which helped in binding the clay particles together. Additionally, other components of the additives, such as potassium hydroxide entered into reaction with some of the components of the clays as muscovite, silica and kaolinite to produce cementitious material.
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A Thesis submitted to the Department of Materials Engineering, Kwame Nkrumah University of Science and Technology,in partial fulfilment of the requirements for the degree of Doctor of Philosophy,
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