Constructing Highway Pavements over Soft Clay Soil Improved by Quicklime

Abstract

The national network of highways has been monotonically increased over the last few years. The increasing need for infrastructure development has led engineers to find safe techniques to construct the infrastructure on soft soils. The design of highway pavement on soft clay soil still remains a very challenging issue. It often causes problems, such as roadbed instability or excessive settlement. As a result, soft soil roadbed treatment has become more and more important. The study aims at improving the clay soil by different methods to sustain the suitable pavement section and its traffic loads. In this paper, soft clay soil is stabilized with quicklime in order to determine the optimum percent of quicklime, which increases the CBR ratios to acceptable values. Results showed that adding quicklime to soft clay enhances its properties to a great extent. However, a 7% quicklime achieved the optimum enhance n properties at which the modulus of compressibility (Es) is improved by 2.87%, and the CBR by 11.2%. Using cyclic loading model device, the measured settlements under the pavement are 12, 7.21and 3.49 mm for soft clay improved by quicklime, using geotextile and using geotextile with geogrid together, respectively