Most projects are built on soils that are higher than the underground water level, and this causes the soil to be in an unsaturated phase. Increasing or decreasing the degree of saturation of soil significantly affects the mechanical and hydraulic properties of the soil. Swelling soils increase in volume by absorbing moisture and reducing matric suction. The presence of these soils in the Refinery area when exposed to water, has caused the rotten casing pipes of the gas wells to be stretched and ruptured. Therefore, this issue causes irreparable damage to various buildings and industries, including oil and gas facilities. In this research, an unsaturated oedometer with a suction control capability was used to investigate the volume changes of expansive soils. In these experiments, the swelling pressure of the soil was studied in different matric suctions. In the second step, cement was used as an additive to control the swelling pressure. In the second group of tests, the sample\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\'s swelling and volume change was performed based on changes in matric suction under constant surcharge. It was observed that the amount of volume change in the free swelling state, where the soil has the highest swelling value, was 6.82%. Also, the swelling pressure of the soil was measured at 99.8 kPa. When the cement additive was used at 2.5 to 10% for improvement, the swelling pressure was reduced by 50 to 95%, respectively

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