Journal of Engineering Science and Technology Review 11 (6) (2018) 156- 161 Research Article Feasibility of Calcium Chloride Dehydrate as Stabilizing Agent for Expansive Soil Abdulla A. Sharo*, Yusuf Alhowaidi and Mohammad S. Al-Tawaha Department of Civil Engineering, Jordan University of Science and Technology, P.O. Box 3030, Irbid 22110, Jordan Received 7 October 2018; Accepted 29 December 2018 ___________________________________________________________________________________________ Abstract The effectiveness of stabilizing expansive soil by enhancing its geotechnical properties using calcium chloride dehydrate (CaCl 2 .2H 2 O) as a soil stabilizing agent was investigated in this research. The chemical treatment process using calcium chloride elaborates carrying out experimental laboratory tests on an expansive soil taken from eastern side of Irbid city (Jordan) to check the influence of calcium chloride on its geotechnical engineering properties. Calcium chloride (CaCl 2 ) was added as a solution of 1.0 N concentration with 3:1 solution to soil ratio and soaked to allow for the occurrence of chemical reaction. The main soil properties studied in this work were the consistency limits, maximum dry density, optimum moisture content, the unconfined compression strength of the soil, swelling percentage, swell pressure and the Californian bearing ration test (CBR). Tests results, at different curing time, revealed that calcium chloride can be considered as a good stabilizing agent for expansive soil since its use displayed a significant reduction in swelling potential (80%) and swelling pressure (50%) after 28 of curing. Also, the use of CaCl 2 enhances soil strength properties by increasing the unconfined compression strength (q u ), increasing the maximum dry unit weight (γ d−max .) and increasing the CBR from 2.11 % to 8.32 %. Keywords: expansive soil, chemical stabilization, curing, swells potential, calcium chloride. ____________________________________________________________________________________________ 1. Introduction In several areas over the world, expansive soils stance significant damages to structure especially the lightweight buildings. The occurrence of these damages may take place slowly over time; moreover, these damages may cost a yearly loss of several billion dollars. To cause foundation harms, expansive soil must experience fluctuations in the amount of moisture it contains causing cyclic of wetting (soil swell) and drying (soil shrink). The swell/shrink potential and the tremendous pressure that expansive soil exerts on structures foundations may be the key to the damaging power of expansive clay in generating foundation problems. In new developments, where expansive soil is a concern, the engineer may require to control the possible damage effect due to the presence of swell/shrink soil in such a way the harm to the new projects foundations will be minimum. A lot of research work has been conducted to find a reasonable solution for this problem. Soil stabilization is one of the most widely used methods in treating problems associated with swell/shrink soil. Stabilization is the process of which soil properties improved by mixing with other available materials called “stabilizing agent” which is commonly used to give better soil strength, reduction in consistency index, and to eliminates the swell potential to some extent. Soil stabilization can be achieved by chemical and mechanical techniques [1]. Irbid city, located in northern part of Jordan (see Fig. 1), is well-known to have a highly expansive soil especially at the eastern side of the city. Enormous cracks in buildings, pavements, and light structures were observed. Based on that, investigations of soils stabilization were necessitated. Many studies were carried on Irbid soils to reduce the swell potential and increase the soil strength. Sharo et al. [2] concluded that oil shale ash can be used to enhance these properties. A burned olive waste, waste paper sludge, lime, and cement were examined by [3, 4] and prove to be good stabilizers. Nanoclay materials were also showed good results in improving strength properties of expansive soil derived from Irbid city [5]. Most of the literature studies carried out all over the world had concentrated on the use of lime and cement [6, 7] and on the use a blend of lime and cement [8, 9]. Moreover, they found that cement's effect dominant on the strength of soil at all time. Lime plays significant role in reduction of swell potential and plastic limit through a flocculation, cation exchange and pozzolanics reactions mechanisms. A little data showed negative effect of cement on the soil strength. Saride et al. [10] attributed the reduction of organic clay strength when added cement to reduce pH concentration. Lime had increased the swell potential in sulfate bearing clay through ettringite formation of lime within chemical reaction. Kim et al. [11] conducted intensive investigation on the possibility of using ground bottom ash (GBA) and red mud (RM) in soil stabilization methods and concluded that the addition of GBA, RM and chemical activators enhanced strength development especially after 28 days of curing. Also, expansive soil chemical treatments which are intended to change the clay mineralogy and lessen the expansion potential are available. Chemical stabilization techniques include treatment of soil by ionic, polymer, and enzyme had little attention in the literature. There were many concerns about the durability of chemical stabilization. However, de Carvalho et al. [12] used different cationic JOURNAL OF Engineering Science and Technology Review www.jestr.org Jestr ______________ *E-mail address: aasharo@just.edu.jo ISSN: 1791-2377 © 2018 Eastern Macedonia and Thrace Institute of Technology. All rights reserved. doi:10.25103/jestr.116.19