Abstract:

Due to continued growth and rapid development of road construction, identification and recognition of type of soil and soil behaviour in different condition help us to select soil according to specification and engineering characteristic, also if necessary sometimes stabilize the soil and treat undesirable properties of soils by adding materials such as bitumen, lime, cement and etc. If the soil under pavement is not done according to the standards, construction will need more cost and construction time. In this case, a large part of soil should be removed, transported and sometimes deposited. Then purchased sand and gravel is transported to the site and full depth filled and compacted. Stabilization by cement or other treats gives an opportunity to use the existing soil as a base material instead of removing it and purchasing and transporting stabilized materials. In this study soil classification and the relation between soil classification and stabilization method is discussed, cement stabilization with different percentages have been selected for soil treatment based on National Cooperative Highway Research Program (NCHRP). In this study California Bearing Ratio (CBR) will be used to define the strength. Because for flexible pavements, the subgrade is considered an ideal layer to withstand wheel load, and the CBR value is considered a force measuring parameter.  0%, 3%, 7% and 10% cement were added to different soil types to evaluate its effect on CBR values and plasticity properties of treated soil. Results showed that cement addition increased CBR values of different soil types by the rate of 22-69%.

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