Abstract
This thesis deals with studying the effect of salts Solutions washing on the characteristics of expansive soil. The expansive soil was brought from three areas of Mosul city (The Yarmouk district, University of Mosul, and AL- Kasak). It emerged from the tests that the soils swelling properties are medium to high depend on clay contents. Where the results of the mineral analysis by X-ray diffraction device showed that the soils have the clay minerals: Montmorillonite, Kaolinite, Illite, Chlorite, and Palygorskite. But there is difference in the proportions of (quantity) clay minerals.
Three types of salts solutions are used in the washing, {Sodium Chloride (NaCl), Potassium Chloride (KCl), and Calcium Chloride (CaCl2)}. To determine the effect of the washing for each ion on the index and swelling properties of the chosen soils sample, solutions were prepared at rates (1%, 3%, and 5%) in form of weight percentage, and three times washing for each rate.
The results showed a decrease in the amount of liquidity limit and the plasticity index of the soils in the first wash by salts solutions. with as increasing the rate and number of washing it obtained change (low and high) in the amount of liquidity limit and plasticity index of soils.
Also the results showed that the rate of reduction in the plasticity index of soils that washed by potassium chloride was the highest than soils that washed by sodium chloride and calcium chloride. And the optimum effect rates of washing by salts solution on the plasticity index are 3% of Potassium Chloride in the third wash for Yarmouk soil (clayey low plasticity soil ), 5% of Potassium Chloride in the second wash for University soil (clayey high plasticity soil), and 1% of Potassium Chloride in the third wash for AL- Kasak soil (clayey high plasticity soil).
The results indicated that the first wash effect of salts solutions in the swelling properties of the soils that compacted at Optimum Moisture Content (OMC) and Maximum Dry Density (gd max) taken from the Modified compaction curve, led to a reduction in the values of swelling properties as an increase in washing rate by salts solution. The results showed a reduction in the swelling properties in the first wash of the Yarmouk soil by potassium chloride at higher rate than using solution of sodium chloride and calcium. Also the results showed a reduction in the swelling properties in the first wash of the University and AL Kasak soils by calcium chloride at higher rate than using solution of potassium chloride and sodium. And the multiple wash led to change (low and high) in the swelling properties. The optimum effect rates of washing by salts solution on the swelling properties are 5% of Potassium Chloride in the first wash for Yarmouk soil (clayey low plasticity soil), 5% of Calcium Chloride in the first wash for University soil (clayey high plasticity soil), 5% Calcium Chloride in the third wash for AL- Kasak soil (clayey high plasticity soil).