Browsing by Author "Abebe, Arega"

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    The Effect of Random Inclusion of Teff Straw on Shear Strength Characteristics of Addis Ababa Expansive Soil
    (Addis Ababa University, 2020-06) Abebe, Arega; Been, Im Soo (PhD)
    Investigation of agricultural crop products as a reinforcement material in Geotechnical engineering has brought both economic and environmental advantages due to rising cost of the physical and/or chemical methods of conventional soil stabilization. In Ethiopia, there is huge byproduct of teff straw which is used as reinforcing material for the locally constructed mud houses. This research work focuses on using of teff straw with varying percentages and examines its effects on shear strength characteristics of expansive soils. The laboratory investigations conducted includes particle size analysis, free swell test, Atterberg limit tests, unsoaked CBR tests and unconfined compression tests. Accordingly, the investigation of the soil belongs to A-7-5 class of soil in the AASHTO classification system and CH in the USCS classification which has very poor strength. The soil was reinforced with teff straw in stepped proportions of 0.2%,0.4%,0.6%,0.8% and 1% by dry weight of soil. The test results reveal that the inclusion of randomly distributed teff straw in the soil increases unconfined compressive strength and unsoaked CBR values and reduces the liquid limit and plasticity index of the treated soil. It is observed that the optimum teff straw content for achieving maximum unconfined compressive strength and unsoaked CBR is 0.6% in terms of dry weight of the soil.