Soil is one of the construction materials used in civil works projects. The soil of the subgrade and its strength are critical for the construction of pavement. Soil improvement is usually necessary if the soil is weak. In order to increase its strength, improving the soil strength may reduce the cost and thickness of the pavement structure, and the main objective of this study is to add bitumen to the soil to improve its quality, the main objective of this study is to add bitumen to the soil to improve its quality. Bitumen mixtures of (2%, 4%, 6%, and 8%) The tests in this study included physical and mechanical properties of soil, Compaction, Atterberg limit, and CBR test without and with soaking and unconfined compressive strength (UCS). The results showed that the use of bitumen led to an increase in the maximum dry density and a decrease in the optimum water content at the ratios of 8%. The results also showed that the CBR values increased at 8%, while the unconfined compressive strength decreased at 8% addition. This study concluded that the use of bitumen improved the properties of the expansive soil, and this type of soil can be used in road works without causing problems in the future.
