STABILIZATION OF EXPANSIVE SUBGRADE SOIL USING PUMICE AND CRUSHED STONE DUST: (A CASE JIMMA TO CHIDA ROAD SEGMENT)

Abstract

Expansive soils are the most abundant soils in the world, and in Ethiopia, this expansive soil covers more than 40% of the total land area. Road construction along in such types of soils causes significant damage to road pavement due to its characteristics of high shrinkage, low bearing capacity, and high swelling potential. These problems need a wider application of cost-effective and environmentally friendly technology to improve this type of soil properties to be adopted in the current highway construction industries. The engineering properties of expansive soil can be improved by one of the methods, through stabilization. Therefore, this study focused on stabilizing expansive subgrade soil using pumice blended with crushed stone dust. The purposive sampling technique which is a non-probability method was used. Samples of soil were collected from Jimma to Chida road below 1.5 m from the original ground level. Pumice from Konta Special district and crushed stone dust from crusher plant. The research was done on an expansive soil sample from Jimma to Chida road, stabilized with the addition of the equal amount of pumice and crushed stone dust by varying content of stabilizers in a steeped concentration of 10, 20, 30, and 40% by dry weight of the soil, was used to stabilize the natural soil. For the analysis of the effect of the stabilizer on expansive soil, a comparison was made on the engineering properties of the native soil and stabilized soil. The engineering properties of natural soil shows that the sampled soils were very weak clay soil and the parameter, CBR (%), = 1.1 and 1.7 and PI (%) = 53 and 41 for sample-1 and sample -2 respectively. The result from stabilization shows that the addition of pumice and crushed stone dust reduces linear shrinkage, free swell, PI, Swelling, and the OMC, increase in MDD& CBR with an increase of pumice and crushed stone dust by considered amount increase of 5, 10, 15, and 20 % of each pumice and crushed stone dust by dry weight of soil for sample -1 and sample -2 respectively. About 26.77% amount of cost savings is also possible when the expansive subgrade soil is stabilized with pumice and crushed stone dust. Stabilizing expansive subgrade soil using pumice blended with crushed stone dust is an economical and effective option for the improvement of expansive subgrade soil properties