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
