Amelioration of Soil Expansion Using Sodium Chloride with Long-Term Monitoring of Microstructural and Mineralogical Alterations.

The impact of chemical additives on the engineering properties of expansive soils has been studied in the past few years; however, the swelling properties as well as mineralogical and microstructural characteristics of expansive clay soils stabilized with NaCl solutions have not been clearly studied. This research work aims at investigating the expansion behavior of the studied clay soil before and after the treatment with a NaCl solution. It also aims to interpret the change in the soil geotechnical properties by monitoring the mineralogical and microstructural alterations. The treatment was performed with different NaCl doses (2.5–12.5%) for different curing times using various water amounts. The mineralogical and microstructural composition of NaCl-stabilized soil samples were analyzed by means of x-ray diffraction analysis, thermal analysis, and scanning electron microscopy. The test results indicated that the NaCl solution reduced the soil swelling in the short term significantly. The amount of water used in NaCl treatment considerably affected its performance. The mineralogical alteration of disappearance of the montmorillonite mineral from the composition of the NaCl-stabilized soil sample interpreted the reduction in the soil swelling in the short term. The 90 days, 12.5% NaCl-stabilized soil sample had densely packed cement block-like microstructure. This resulted from the binding of the soil clay aggregates by the newly formed cementitious products. [ABSTRACT FROM AUTHOR]