Abstract— An expansive soil is any soil that is prone to large volume changes (shrinking and swelling) directly related to changing moisture conditions. The swelling capacity can cause heaving, or lifting of structures whilst shrinkage can cause differential settlement. The amounts by which the ground can shrink and/ or swell depend not only on the supply of moisture in the ground but also on the type and amount of clay minerals, internal structure and void ratios of the soil. Characterization of swelling potential is critically important to mitigate the adverse effects of expansive soils. Therefore, this study uses the coefficient of linear extensibility (COLE) as the controlling method to characterize swelling potential of expansive soils. The samples for this test were retrieved from two different locations in areas prone with expansive soils in Kibaha Township in Tanzania. Bulk density was determined on irregular soil clods and COLE was calculated as the difference between bulk density values at 1/3 bar and oven-dry condition. The coefficient of linear extensibility that ranged from 0.09 to 1.15 clearly indicated soils with high to very high shrink–swell potential. Lastly, a direct relationship existed between COLE and colloids contents with high degree of correlation (i.e. Correlation Coefficients (R) equal to 0.942 and 0.824 for samples RC5 and RB3 respectively) providing a confirmation to the presence of high to very high expansive potential of the soils.
Keywords— Expansive soil, coefficient of linear extensibility (COLE), Clay content and shrink-swell potential.
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