EXPANSIVE SOIL STABILIZATION WITH CINDER MATERIAL AS ASUBGRADE FOR ROAD CONSTRUCTION

In Ethiopia expansive soil is distributed in different parts of the country in which major constructions activities are increasing on those areas. This type of soil is problematic to different engineering structures due to its tendency of swelling during wet season and shrink during dry season. To overcome this problem soil stabilization is the best alternative. This study deals with investigating stabilization of expansive clay soil by cinder gravel used as a road sub grade material. To meet the research goal the expansive soil samples collected from Addis Ababa and stabilization carried out with addition of varying percentage of cinder gravel in the experimental investigation. The percentage of stabilizer varied in an increasing concentration of 20%, 30%, 40% and 50% by dry weight of the soil. To analyze the effect of cinder addition on expansive soil, comparison made on engineering properties of native soil and stabilized soil. The comparison includes: Atterberg limit, linear shrinkage, free swell index, compaction, California bearing ratio (CBR) and unconfined compressive strength of both native and stabilized soil samples. The result shows that addition of 50% cinder decreases plasticity index from 44% to 21%, reduced 115% of free swell value of native soil to 55%, reduced 24% linear shrinkage value of native soil to 12% and increases the CBR value from 1%of native soil to 4.23% stabilized soil.