Abstract—Chemical stabilization is a technique commonly used to improve the expansive soil properties. In this regard, an attempt has been made to evaluate the influence of Calcium Chloride (CaCl 2 ) stabilizer on the engineering properties of expansive soil. A series of laboratory experiments including consistency limits, free swell, compaction, and shear strength tests were performed to investigate the effect of CaCl 2 additive with various percentages 0%, 2%, 5%, 10% and 15% for improving expansive soil. The results obtained shows that the increase in the percentage of CaCl 2 decreased the liquid limit and plasticity index leading to significant reduction in the free swell index. This, in turn, increased the maximum dry density and decreased the optimum moisture content which results in greater strength. The unconfined compressive strength of soil stabilized with 5% CaCl 2 increased approximately by 50% as compared to virgin soil. It can be concluded that CaCl 2 had shown promising influence on the strength and swelling properties of expansive soil, thereby giving an advantage in improving problematic expansive soil. Keywords—Calcium chloride, chemical stabilization, expansive soil, improving. I. INTRODUCTION XPANSIVE soil is one of the problematic soils that has a high potential for swelling and shrinking due to change in moisture content. This behaviour of soil is attributed to the presence of mineral montmorillonite, which has an expanding lattice. Expansive soils cover considerable land area of most countries of the world. Sudan is one of the countries with a wide distribution of expansive soils. Over one–third of the country total area has expansive soils. The major problem that arises with regard to expansive soils is that deformations are significantly great, which results in extensive damage to the structures resting on them, [1]. Proper remedial techniques are to be adopted to modify the soil or reduce its swelling potential. Many stabilization techniques are in practice for improving the expansive soils in which the characteristics of the soils are altered. Chemical additives such as lime, cement, bitumen, fly ashes, calcium chloride etc. are commonly used to alter the characteristics of the expansive soils. The main characteristics that are of concern to the geotechnical engineers are strength, swelling, compressibility and durability. The effect of the chemical additives and the optimum amount of additives to be used are dependent mainly on the mineralogical composition of the soils. In this research, the possibility of stabilizing expansive M. M. Zumrwai is with Civil Engineering Department, University of Khartoum, Khartoum, Sudan (phone: 00249912355758; e-mail: magdi.zumrawi@yahoo.com). K. A. Eltayeb is M.Sc. student, Civil Engineering Department, University of Khartoum, Khartoum, Sudan (phone: 002490124906597). soil with a chemical stabilizer such as calcium chloride (CaCl 2 ) is investigated. The objective of the present study is to study the effect of adding CaCl 2 on the engineering properties of expansive soil. II. LITERATURE REVIEW Expansive soils pose the greatest hazards that many geotechnical engineers face. Such soils may cause heavy damages in light loaded structures such as water canals, reservoirs, highways, railways and airport runways etc., unless appropriate measures are taken. Various stabilization techniques are in practice for improving expansive soils by reducing its swelling potential and increasing its strength characteristics. Modification of expansive soil by chemical admixture is a common practice for stabilizing the swell- shrink tendency of expansive soil, [2]. Advantages of chemical stabilization are that they reduce the swell-shrink tendency of expansive soils and also render the soils less plastic. In this section, the experiences of various investigators concerning chemical stabilization using calcium chloride have been reviewed. Numerous investigators, [3]–[7], have studied the influence of lime, cement, lime-cement, lime-fly ash, and cement–fly ash mixes on soil properties, mostly focusing on the strength and swelling aspects. Among the chemical stabilization methods for expansive soils, lime stabilization is mostly adopted for improving the swell-shrink characteristics of expansive soils. As lime and cement are binding materials, the strength of soil-additive mixtures increases provided the soil is reactive with them. However, for large-scale field use, the problems of soil pulverization and mixing of additives with soil have been reported by several investigators [2], [3], [8], [9]. Calcium chloride is an inorganic salt, which is a by-product of sodium carbonates. The use of calcium chloride in place of lime, as calcium chloride is more easily made into calcium charged supernatant than lime, [10]. A recent study indicated that CaCl 2 could be an effective alternative to conventional lime used due to its ready dissolvability in water and to supply adequate calcium ions for exchange reactions, [11]. Calcium chloride is known to be more easily made into calcium charged supernatant than lime and helps in ready cation exchange reactions, [9]. CaCl 2 might be effective in soils with expanding lattice clays, [12]. The bibliography on stabilization of soil and calcium chloride is giving its wide use in highways, [8]. Hausmann [13] and Shepard [14] have stated that CaCl 2 enjoyed its wide use as dust palliative and frost control of subgrade soil. Calcium chloride has hygroscopic Laboratory Investigation of Expansive Soil Stabilized with Calcium Chloride Magdi M. E. Zumrawi, Khalid A. Eltayeb E World Academy of Science, Engineering and Technology International Journal of Environmental, Chemical, Ecological, Geological and Geophysical Engineering Vol:10, No:2, 2016 199 International Scholarly and Scientific Research & Innovation 10(2) 2016 scholar.waset.org/1999.6/10003855 International Science Index, Geological and Environmental Engineering Vol:10, No:2, 2016 waset.org/Publication/10003855