Henok, Fikre (PhD)Desta, Berhane2019-01-172023-11-112019-01-172023-11-112018-06http://etd.aau.edu.et/handle/12345678/15832Soil stabilization is the process of improving the shear strength parameters of soil and thus increasing the bearing capacity of soil. It is required when the soil available for construction is not suitable to carry structural load. Soils exhibit generally undesirable engineering properties. Soil Stabilization is the alteration of soils to enhance their physical properties. Stabilization can increase the shear strength of a soil and/or control the shrink-swell properties of a soil, thus improving the load bearing capacity of a sub-grade to support pavements and foundations. Soil stabilization is used to reduce permeability and compressibility of the soil mass in earth structures. In this thesis study, pumice has been used to stabilize black cotton soil due to its mineralogical content which will act to have a cementitious property and will undergoes pozzolanic reaction and able to alter the black cotton soil property to a certain degree. The natural pumice material excavated from quarry source and passing 4.75mm sieve was used as stabilizing material. On the process of testing of the soil-pumice mix, the pumice material was subjected to compaction effort which causes crushing of the pumice to a certain extent. Hence, all test results and conclusion were drawn based on partially crushed pumice material in the soil-pumice mix. The effect of pumice as a form of powder and mixed with black cotton soil was not conducted and determined. Hence, further investigation shall be carried out to determine the outcomes of powdered pumice material to its stabilization property after mixing with expansive clay soil. In this regard an attempt has been made to evaluate the effect of pumice as a stabilizer on the geotechnical properties of black clay soil in stabilized form specifically strength, compaction and swelling characteristics. Therefore, series of laboratory tests such as Atterberg limits, free swell index, compaction, unconfined compressive strength, soaked CBR and swelling pressure tests for different percentages of pumice were performed .The soil was stabilized with pumice in stepped concentration of 10%, 20%, 30%, 40%, 50%, and 60% by dry weight of the soil. Analysis of the results shows slight improvement on the geotechnical properties of pumice stabilized soil. Pumice slightly reduces the index properties of the black clay soil as well as the heaving tendency of the soil. Pumice is known to its light weight property due to that the MDD of the soil decreases as the ratio of the pumice increased in the clay soil. Moreover, the CBR-Swell, free swell and one dimensional swelling pressure shows a decrease as the pumice ratio increases in the clay soil.en-USBlack Cotton SoilBlendingInvestigationPumiceThesis