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dc.contributor.authorGuo, Rui
dc.date.accessioned2019-06-05T19:03:37Z
dc.date.available2019-06-05T19:03:37Z
dc.date.issued2018-12
dc.identifier.urihttp://hdl.handle.net/11122/10247
dc.descriptionMaster's Project (M.S.) University of Alaska Fairbanks, 2018en_US
dc.description.abstractUnfrozen water within cation-treated, fine-grained frozen soils is a key element in cold regions engineering, and is heavily influenced by the surface charge of the soil's clay component. This study investigated the effects of the surface charge of cation-treated clay soils by measuring the zeta potential as a function of temperature, and measuring changes in the micro-structure of frozen cation-treated clays using the x-ray diffraction (XRD) method. I tested five treatments (untreated, and Ca²⁺, Mg²⁺, Na⁺, and K⁺ treatments) of six soils (montmorillonite, kaolinite, illite, illite-smectite, chlorite, and Copper River soil). The zeta potential demonstrated a negative relationship with temperature change for both above-freezing and sub-freezing conditions (-1 to 20 °C). Temperature had a greater effect on the monovalent-treated soils that contain smectite minerals, which included montmorillonite, illite-smectite, and the Copper River soil. Monovalent cation-treated soils demonstrated large negative trends and more negative zeta potential, whereas divalent cation-treated soils demonstrated less negative trends that were less dependent on temperature. The cation treatment will affect the Debye-length, also affecting the zeta potential and arrangement of clay particles. More negative zeta potential (i.e., soil dominated by monovalent cations) will lead to a dispersed structure, whereas less negative zeta potential (i.e., soil dominated by divalent cations) will lead to a flocculated structure. XRD research indicated that the montmorillonite samples demonstrated decreased dspacing compared with the International Center for Diffraction Data (ICDD) standard. The K⁺- treated montmorillonite, untreated montmorillonite, and untreated illite-smectite samples demonstrated donut-shaped pole figure results, which may indicate that the results are an artifact of sample preparation rather than a reflection of the cation effects on the structure of the clay. Improved could be made in sample preparation to eliminate ice lens formation during freezing, which may improve the success with the XRD method. Scanning electron microscopy (SEM) should be used to observe the frozen clays, especially montmorillonite, illite-smectite, and the Copper River soil, as it may reveal the internal geometry of voids and the possible relationship between ice and the clay structure, increasing our understanding of the clay structure at the microaggregate scale.en_US
dc.description.sponsorshipThis research was supported by the National Science Foundation under Grant No. 1147806.en_US
dc.language.isoen_USen_US
dc.subjectClay soilsen_US
dc.subjectAnalysisen_US
dc.subjectClayen_US
dc.subjectMontmorilloniteen_US
dc.subjectKaoliniteen_US
dc.subjectIlliteen_US
dc.subjectSmectiteen_US
dc.subjectChlorite mineralsen_US
dc.subjectFrozen grounden_US
dc.subjectZeta potentialen_US
dc.titleAnalysis of cation-treated clay microstructure using zeta potential and x-ray diffractionen_US
dc.typeOtheren_US
dc.type.degreems
dc.identifier.departmentDepartment of Mining and Geological Engineering
dc.contributor.chairDarrow, Margaret .
dc.contributor.committeeMetz, Paul A.
dc.contributor.committeeTrainor, Thomas P.
refterms.dateFOA2020-03-06T02:15:24Z


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