Laboratory Study on the Effect of Water Cations’ Concentrations on the Bojnord Clay Consolidation Process

Document Type: Research Note

Authors

1 Associate Professor, Department of Civil Engineering, Payame Noor University, P.O. Box 19395-4697, Tehran, I.R. Iran

2 Ph.D. Scholar, Department of Civil Engineering, Faculty of Engineering, Central Tehran Branch, Islamic Azad University, Tehran, I.R. Iran

Abstract

The initial consolidation settlement process of saturated cohesive soils has been one of the most important issues to geotechnical engineers especially in important and sensitive structures based which are located on saturated clay layer with high thickness.  In dealing with initial consolidation settlement process and reducing its negative and destructive consequences, a number of solutions have been presented including but not limited to the implementation of horizontal and vertical sand drainages, pre-loading and dynamic compaction; limitations of these methods include the necessity of implementing them before construction of the project. Furthermore, if the underground water level goes lower than regarded values, no appropriate approach else than the overhead reduction approach has been provided. In present research, with addition of concentrations of 250, 750 and 1250 Mg/lit in saturated water, laboratory study of the changes in initial consolidation settlement process, were investigated by standard Oedometer test device upon the addition of different concentrations of the cations, dissolved in saturated water on cylindrical samples of Bojnord clay with 2cm in height and 7.5cm in diameter. Achieved results represent significant changes in quantities of initial consolidation settlement process upon adding a variety of dissolved cations in saturated water; The results show that application of cations including aluminum (Al+3), calcium (Ca+2), magnesium (Mg+2), sodium (Na+) and potassium (K+) with different concentrations changes the values of initial consolidation settlement values in appropriate with type and concentration of cations that the highest reduction of the initial consolidation settlement of Bojnord clay valued at 24.61% for the sample made with Al+3 cation with ionic concentration of 1250 Mg/lit.

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