Various subgrade improvement methods are developed for decreasing deformations, vertical stresses, increasing the bearing capacity, and the other stiffnes charazterizations (California Bearing Ratio (CBR), Resillient Modulus (Mr), Modulus of Subgrade Reaction (K) values) of solf clayey subgrade. In this thesis study, pavement subgrade stabilization with lime stabilization and geocell reinforcement are investigated. In this study lime stabilization and geocell reinforcement techniques were investigated for clayey type pavement subgrade with high water content and finally a comparison of these techniques were made. For this purpose, CBR tests were conducted on clayey subgrade soil with 20 % water connet higher than its optimum water content and mixed with different percentages of hydrate lime (%5, %10, %15 dry wight of the soil). The wet CBR values of % 15 lime stabilized soil were increased from % 0,2 to % 7 compared to its natural condition. Plate loading tests were performed on the same soil conditions. The test results indicate that lime stabilization or gocell reinforcement alone does not siginificantly reduce the deformation and vertical stresess, and does not increase subgrade reaction coeffecient (K) and bearing capacity values. Howevere, it was found that when both techniques are used together promising results are obtained on stabilization of the pavement with high water content clayey subgrade.
Key worlds: Geocell Reinforcement System, Lime Stabilization, Pavement Subgrade,Bearing Capacity, CBR, Clayey Subgrade with High Water Content