Dispersive Soil Treatment; a Case Study Along Melkasa-Sodere-Nurera-Metahara Road Project, Central Ethiopia
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Date
2020-06-06
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Addis Ababa University
Abstract
Portland pozzolana cement (PPC) and Gypsum were used as a stabilizer to treat dispersive
subgrade soil along the Melkasa-Sodere-Nurera-Metahara Road project. Experimental
laboratory investigation were carried out on two subgrade soil samples to determine the
engineering properties of stabilized soils. The untreated soil samples collected from two
different locations show a dispersion potential of 69.9 and 99.1 percent, respectively
evaluated on a double hydrometer test.
Treated soil samples were prepared by varying the amount of cement from 1.0 to 5.5
percent by weight of dry soil sample and gypsum from 2.0 to 8.0 percent by weight of dry
soil. The treated samples were evaluated for dispersion potential by double hydrometer test
and unconfined compressive strength. The result was evaluated based on the Decker and
Sherard dispersive soil classification criteria.
The samples treated with cement had shown a huge improvement interms of dispersion
potential and satify the non-dispersive soil classification based on the Decker and Sherard
criteria at 1 and 2.5 percent for samples A and B respectively. These samples show a higher
incement in compresssive strength too. The gypsum treated samples, even if shows a huge
improvement in dispersion potenetial, they were failed to satisfy the non-dispersive soil
classification based on the crieteria set by Decker and Sherard and it is not considered for
treatment of the current subgrade soil. The strength development of soil samples treated
with gypsum are lower as compared to cement treated samples.
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Keywords
Portland Pozzolana Cement, Gypsum, Dispersive Soil, Soil Treatment