Dispersion characteristics of MgO-treated dispersive clay

Abstract

The improper use of dispersive base soils has had far-reaching consequences in geotechnical structures but most significantly the cores of earth dams, road embankments, and irrigation channels. When exposed to water, the dispersive clay transforms into individual colloidal particles before getting washed. Dispersive clay is one with a large amount of sodium ions in its pore water. The laboratory tests included pinhole test, crumb test, and double hydrometer test on natural nondispersive clay prepared at three undrained shear strengths and dispersive clay prepared by adding 35% of Na2CO3 to the natural clay. Then, the soil treatment of the dispersive clay was made by mixing with different percentages of MgO. The MgO caused a change in soil fabric from a de-flocculated structure to a more flocculated one. The fines content generally decreased due to the MgO treatment, and when MgO increased, the sodium component in the dispersed soil decreased. Another criterion for identifying the dispersion of soil based on the output flow turbidity has been proposed through carrying out turbidity test on the output water. It is shown that in dispersive clay, there is a steady increase in turbidity with clay undrained shear strength after both tests (pinhole and crumb tests). A significant reduction in flow rate was recorded when the MgO increased from 0 to 6%. Another criterion for identifying the dispersion of soil based on the output flow turbidity has been proposed through carrying out turbidity test on the output water. It is shown that in dispersive clay, there is a steady increase in turbidity with clay undrained shear strength after both tests (pinhole and crumb tests).