Laboratory study of expansive soil treatment using consecutive wetting and drying cycles

Subject Areas : Farm water management with the aim of improving irrigation management indicators

Amin Soltani ¹ ( MSc. Student, Department of Irrigation and Reclamation Engineering, University of Tehran, Karaj, Faculty of Agricultural Engineering & Technology, College of Agriculture & Natural Resources, University of Tehran, Karaj, Tehran, Iran )
Ali Raeesi Estabragh ² ( Associate Professor, Department of Irrigation & Reclamation Engineering, Faculty of Agricultural Engineering & Technology, College of Agriculture & Natural Resources, University of Tehran, Karaj, Tehran, Iran Corresponding author email )

Received: 2013-10-10 Accepted : 2015-02-02 Published : 2014-12-21

Keywords: hysteresis, pore water, swelling and shrinkage paths, water and soil conservation,

Abstract :

Treating problematic soils at the location of irrigation and drainage networks in order to prevent hydraulic structure failure and thus water losses is considered an important issue regarding water and soil conservation. Expansive soils are found in many parts of the world and are considered a worldwide problem as they cause extensive damage to structures (especially hydraulic). This paper presents the laboratory results of wetting and drying cycles for expansive clay prepared with saline (sodium chloride with a concentration of 50 g/L) to improve its quality. Soil samples were prepared by static compaction using saline water and wetting and drying cycles by a modified and conventional Oedometer apparatus. Results indicated that axial deformation caused by consecutive wetting and drying cycles decreases and reaches equilibrium after five consecutive cycles thus causing the amount of swelling and shrinkage to be equal. Furthermore swelling and shrinkage paths (void ratio versus water content paths) indicate that the general shape of a wetting or drying cycle is an S-shaped curve which will reach equilibrium thus eliminating hysteresis caused by wetting and drying in the final cycle causing identical swelling and shrinkage paths.