The effect of salinity on the swelling behavior of expansive soils under wetting and drying cycles

Expansive soils is known as a problematic soil that shows volume changes while subjected to moisture content variation. Volume changing of such soils, specially the basis of light structure like base of canals with rigid lining lead to cause high costs. This type of soils evolve more clay and the magnitude of expansion depend upon to the type of minerals and molecular connections. Furthermore the type of chemical materials which is added to the soil, precise an explanatory definition of engineering properties of the soil. In this research the effect of salinity on the behavior of clayey soils under wetting and drying cycle was investigated. In this regards, three expansive soil sample including; zero, two and four weighty percent of NaCl were prepared and free swelling tests under wetting and drying cycles with monitoring of salinity variation were conducted. The results of this investigation revealed that the maximum expansive is refer to the second cycle, as well the expansive behavior after 6 cycle decrease significantly. Also, the achievements of this study confirmed that in the specimens including salt the gravity forces between ions over clays and cation increases and it cause to decrease of swelling. Whereas, in the specimens including 4% salinity the minimum expansive was shown that this may practical as a simple method to control the expansive behavior of clays.