Published Paper Details:

Expansive soils have a high tendency of swelling and shrinking behavior depending on the seasonal variations; its volume increases during a rainy season and decreases during a dry season. Due to swelling and shrinking characteristics, it brings a major problem on geotechnical engineering structures and devastation to life. A road which is being constructed on expansive soils has no strength to carry a load and cannot resist any stresses. As it was reviewed from different literatures, the combination of lime and CSP stabilizes a problematic soil. The laboratory characteristics of subgrade expansive soils was investigated before and after the addition of lime and coconut shell powder separately and both mixtures to soils at different percentage, thus the properties of these materials was discussed and analyzed for how much they are effective in soil stabilization. Lime and coconut shell powder stabilization is the best option to control the volume changes of fine grained and expansive soils by adding appropriate percentage. Under this research the effectiveness (performance) of Lime and coconut shell powder was analyzed to determine the shear strength and swelling characteristics of expansive soils. The soil classification, Index Property, standard proctor compaction behavior, California Bearing Ratio (CBR), Optimum Moisture Content (OMC), Unconfined Compression Strength (UCS) and Free Swell properties were determined. The lime and CSP stabilized soil increases the value of CBR and UCS; the amount of the material added to the soil has a great impact for the strength being developed. Addition of lime and CSP are the most stabilizers used to reduce the plasticity of the soil and improves the strength of the soil and it brings a permanent modification with an easy manner. The optimum compressive strength of lime and CSP treated soil increases up to 6% and 5% respectively and starts to decreases as the amount of the material increases. The 8% of lime and 7% of CSP mixing together also increases the values of UCS. The increment of UCS due to lime and CSP is due to the initial increment of the moisture content. As the content of lime and CSP increases, the amount of moisture content increases and the dry density of the treated materials decreases due to the low specific gravity of lime and CSP relative to soil.