Amelioration of Soil Expansion Using Sodium Chloride with Long-Term Monitoring of Microstructural and Mineralogical Alte
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RESEARCH ARTICLE-CIVIL ENGINEERING
Amelioration of Soil Expansion Using Sodium Chloride with Long-Term Monitoring of Microstructural and Mineralogical Alterations Gehad Mohamed Hossam Makeen1,2
· Samir Ahmed Awad1 · Hina Dilawar2
Received: 7 April 2020 / Accepted: 17 September 2020 © King Fahd University of Petroleum & Minerals 2020
Abstract 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. Keywords NaCl solution · Geotechnical properties · Soil swelling · Mineralogical alteration
1 Introduction Many Egyptian territories have been experiencing active urbanization since the nineties to face the rapid population growth. The expansive clay soils present in these areas represent serious engineering challenge. Expansive soils experience volumetric change as a result of their water content variation. This can impose severe distress to all engineering structures [1–3]. Normally, expansive soils are not suitable for the construction of infrastructures
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Gehad Mohamed Hossam Makeen [email protected]; [email protected] Samir Ahmed Awad [email protected]; [email protected] Hina Dilawar [email protected]
1
Geology Department, Faculty of Science, Ain Shams University, 11566 Cairo, Egypt
2
School of Engineering, The University of British Columbia, Okanagan Campus, 1137 Alumni Avenue, Kelowna, BC V1V 1V7, Canada
[4, 5]. These problematic soils cover one-fourth of the USA [6]. Moreover, the cost of the yearly global damage caused by these soils likely exceeds $10 billion [7–11]. These soils contain expandable clay minerals, such as montmorillonites, vermiculites, and some mixed-layer
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