The extensive damages to the super structures caused by the swelling soil, has attracted special attention of researchers. Stabilization of swelling soil using different agents is becoming more popular around the world. The modification methods of such problematic soils to enhance their engineering properties is well recognized and widely practiced. Among the various stabilizing efforts, mechanical and chemical stabilization investigated by numerous researchers. A wide range of chemical agents is employed for soil properties improvement, among which lime and cement are the most prominent agents. Most gypsum soils, which possess high porosity, will settle down if they are relatively heavily loaded, and swell if they are compacted. The present research examines the effects of compaction and various unit weights on swell potential and swell pressure. In addition, adding lime and cement to gypsum soil to improve their swelling properties are studied. The test results revealed that although compaction effort leads to settlement reduction, but increases swell potential. Meanwhile, lime and cement can be used to improve such problematic soils and reduce, but not totally eliminate, swell potential and swell pressure.

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