Abstract:
This study aimed to characterize and classified the soil based on index and engineering prop-erty of soil. Samples were collected at 10 different location. Laboratory experimentation was conducted on soil sample collected according to ASTM soil testing procedures.
Laboratory result of particle size distribution indicates that the soil sample were fine grained soil in generally having 39.12%-to-61.38% clay, 34.54%-to-52.28% Silty and 3.4%-to-9% sand. Natural water content ranged from 29.27%–39.45%. In situ density from 1.1 g/cc–1.49g/cc and Specific Gravity ranges from 2.63 to 2.76. From the Atterberg limit test, the soil samples showed LL, PL and PI value ranging from 48 % - 67.5%, 25.6 % - 48.44 % and 11.52 % - 28.91% respectively. The free swell value of the soil ranged from 20%-to-70%. Soils in study area are classified according to USCS and ASSHTO. Unified Soil Classifica-tion System showed that soil falls below the A-line from plasticity chart which was inorganic elastic silt of medium to high plasticity (ML and MH respectively). Classifications of soils in the study area based on AASHTO classification system were classified in group A-7-5, and group index of most sample ranging greater than 20. The group index results indicated that generally the soils of the study area are poor for highway subgrade material. Additionally, us-ing Skempton’s Activity number most of the soil samples were inactive soils. From the com-paction test the maximum dry density (MDD) of ranged from 1.29g/cc –1.54g/cc and the op-timum moisture content (OMC) from 28 %-to- 40.5%. The undrained shear strength of the soil ranged from 49kpa -to-100 kpa. Finally, from one-dimensional consolidation test result under study area, have compression index ranged from 0.07to -0.16 and recompression index ranged from 0.02-to -0.04
From empirical correlation three model are formulated at depth of 1.5m and 3m separately. Only liquid limit and plastic index moderately correlate with compression and decompression
