Journal de géologie et géophysique
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Lime Stabilization of Natural Subgrade Soil along Bishoftu to Koka Road Section, Central Ethiopia

Kuma Kebede

This paper is focused on the treatment of subgrade soil along Bishoftu to the Koka road section by using lime. To achieve the objectives of the research subgrade soils samples were collected along the corridor of the road section and evaluated for its physio-chemical and geotechnical properties. The grain size analysis show the soil contains 13.5% of gravel, 40.3% sand, 25% silt and 21.2% clay and possesses plastic index (PI)>40% and liquid limit (LL)>76% with <5% California bearing ratio (CBR). The soil was classified as A-7-5 in the American Association of State Highway and Transportation Officials (AASHTO) which is considered as a problematic soil for subgrade materials. To determine the effects of lime on geotechnical properties of soil the natural subgrade soil was treated with 3%, 6% and 9% of lime and compacted after a mellowing period of 3 to 4 days and cured for 7, 14 and 28 days. Result shows the soil treated with lime showed lower PI by 33%, OMC by 98% and decrease MDD by 96%, CBR by 24%, with lower swelling potential, higher workability and stabilized soils were feasible to be used as subgrade materials.