Dispersive Soil Treatment; a Case Study Along Melkasa-Sodere-Nurera-Metahara Road Project, Central Ethiopia

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Addis Ababa University


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.



Portland Pozzolana Cement, Gypsum, Dispersive Soil, Soil Treatment