Improving Engineering Properties of High Plasticity Clay Soils Using Electro- osmosis With the Injection of Strontium Chloride

High plasticity clay soils are one of the problematic soils for engineering projects, especially for road construction. Electro-osmosis is one of the methods for improving the characteristics of the soft and fine grained soils. In this method applying the electric field cause changes in microstructure of the soil and modify the physical and chemical properties of the soil. Injecting chemical solution into soil during the electro-osmosis process adopted for enhance the efficiency of the treatment in recent years. The effect of injection of strontium solutions on chemical and geotechnical characteristics of soil was investigated. A layer of the soil was impacted in a tank for obtaining density and field moisture content. Direct current was applied through the soil under voltage gradients of 0.5, 1, and 2 (V/cm) for periods of 7, 14, and 28 days, with and without the injection of strontium solution. Stainless steel electrode was exerted for treatment. The results demonstrated the increases in compressive strength and reduction of the moisture content of the soil. From the results it is noted that injecting strontium increases the compressive strength and volume of drained water compare to electro-osmosis process in absence of strontium. Chemical analysis of the soil before and after the treatment identifies the ionic migration, ionic exchanges and changes in chemical composition of the soil. These chemical changes lead to changes in structure and properties of the soil. The scanning electron microscopy (SEM) images exhibited the changes of the microstructures including flocculation and agglomeration and confirm the validity of physical results. At last, the result of California bearing ratio (CBR) showed that electro osmosis chemical treatment is feasible method to increase the properties of the soil to meet the requirements for subgrade constructions.