The permeable press experiment was performed for aqueous clay mineral systems to understand the relationship between the water film thickness and the applied permeable pressure. Water film thickness between particles was calculated from the particle size and the linear drying shrinkage of pressed bodies. The permeable press experimental results were compared to the calculated total interaction pressures between particles using the DLVO theory. The kaolinite and the metakaolinite had the same particle shape. Kaolinite particles were crystalline, and metakaolinite particles were short-range order. The kaolinite had the point of zero net charge, PZNC, at pH 5.7. However, the kaolinite showed multi-cross points at pHs 4.6, 5.7, 6.2, and 7.2. These multi-cross points were in agreement with the theoretical titration using the two-site surface complex reaction model by Carroll-Webb and Walther. On other hand, the metakaolinite had the PZNC at pH 7.2 as a common intersection point. If the zeta potential at pH(PZNC) is identical to the silica basal surface potential, the silica surface charge densities are calculated as - 2.6 μC cm⁻² for the kaolinite and - 2.7 μC cm⁻² for the metakaolinite, respectively. The calculated surface charge density is equivalent to one aluminum atom substituted in 54 silicon atoms in the silica tetrahedral layer. The total interaction pressures using the DLVO theory corresponded to the permeable press experimental results of the metakaolinite-0.1 M NaCI systems. The surface of the metakaolinite was estimated to have immobile water layers between 5 and 8 molecules thick. The metakaolinite samples cracked in experiments when the applied permeable pressure increased. This phenomenon can be explained by a vanishing capillary pressure: contacting immobile layers. The permeable press experimental results of all the kaolinite systems were significantly higher than the calculated total interaction pressures. The slope of the natural log of the permeable pressure and the water film thickness of the kaolinite systems indicated the existence of a longer-range repulsive pressure than that of the metakaolnite systems. The DLVO theory cannot explain the kaolinite systems because the nature of materials, such as an atomic configuration of the surface, which induces the structural forces, is not considered.

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Includes bibliographical references. / 1 v. : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis investigates the nature and origins of minerals of a group known as layer (sheet) silicates or phyllosilicates. It consists of a collection of research papers grouped into 3 categories: modulated layer silicates, clay silicates and the weathering of rocks and minerals, including the formation of clay minerals. Central to the research has been the use of X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). All three research categories were carried out simultaneously. / Thesis (D.Sc.)--University of Adelaide, Dept. of Geology and Geophysics, 1999

Thesis (Master)--İzmir Institute of Technology,İzmir, 2005 / Includes bibliographical references (leaves. 84-89).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1940. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 68-73).

Thesis (M.S.)--University of Akron, Dept. of Geology, 2005. / "August, 2005." Title from electronic thesis title page (viewed 11/29/2005) Advisor, Annabelle Foss; Committee members, Teresa Cutright, Ira Sasowsky; Department Chair, John Szabo; Dean of the College, Charles B. Monroe; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.

Thesis (M.S.)--Brigham Young University. Dept. of Geology, 2005. / Includes bibliographical references (leaves 36-39).

Loess has a metastable structure and undergoes structural hydrocollapse when loaded and wetted, leading to subsidence and damage of overlying structures, which presents enormous engineering problems in many countries in the world. This problem is a focus of much research on both the nature of the phenomenon and the means. of overcoming its negative consequences. However, there remains a need for fundamental experimental and theoretical studies aimed at understanding the many uncertainties involved in the hydrocollapse phenomenon. An experimental programme has been conducted to study the fundamental nature of the hydrocollapse phenomenon in loess, and the primary features of the metastable structure controlling it. High quality disc-shaped specimens were prepared from natural undisturbed, very soft and slightly cemented loess soils using two simple devices which were designed and manufactured in the laboratory. Artificial loess materials were prepared by mixing pure silt particles of different geometrical characteristics (crushed sand, ballotini glass balls) with various clay types (kaolinite, bentonite) to produce mixes with different clay/silt ratios. Soil specimens of metastable structure were created from natural and model loess materials using the air-fall technique, which allowed full control over the critical variables. The index properties of the materials were determined experimentally, together with their geometrical characteristics from scanning electron microscope (SEM) studies. The compressibility characteristics and hydrocollapse behaviour were measured via one-dimensional (oedometer) compression tests. Two testing methods were used: the single oedometer test and the double oedometer test. The results indicated that the experimental approach used in this research can be used successfully to investigate the hydrocollapse problem of loess deposits. The small-clay loess model was constructed and examined. The results proved that this model is valid. The collapse behaviour of reconstituted and undisturbed loess specimens prepared from the same material was qualitatively similar, although the reconstituted materials exhibited greater collapsibility, particularly under low normal effective stresses. Specimens prepared from pure silt revealed very little collapse in spite of relatively high initial voids ratios (e ≤ 0.9). The existence of bonding materials, such as clay minerals at the points of particle contact, is thus apparently essential for hydrocollapse to occur. Specimens prepared from pure silt-bentonite mixtures exhibited low hydrocollapse values in comparison with those for pure silt-kaolinite mixtures. It was observed that there is an optimum clay mineral content for maximum hydrocollapse and it depends on the type of clay mineral and the level of applied stress. Higher values of hydrocollapse were obtained with smooth, spherical glass balls as the silt fraction, thus confirming that the geometrical properties of the silt particles also have a significant effect on the hydrocollapse behaviour of loess deposits. The position and distribution (mixing method) of clay particles inside the soil structure were equally found to have a significant effect on the hydrocollapse behaviour. The index properties of Libyan loess were found to be very similar to those of other loess deposits world-wide. The Tripoli loess can be classified as silty loess with high susceptibility to structural hydrocollapse in the same manner as other better known loess deposits in the world.

X-ray diffraction studies of 29 Virginia Blue Ridge and Piedmont soil profiles and petrographic examinations of the parent rocks reveal that even after prolonged chemical weathering, physical and mineralogical differences exist between soil types which are due largely to changes in the parent rock, and to a lesser extent changes in the topography. Soils developed from different source rocks can be distinguished on the basis of color, texture, degree of contrast between horizons, and depth to fresh rock. The clay minerals of such soils differ in their distribution, amount and kind. The role of parent material in soil and clay mineral formation is a complex function of several variables: (1) chemical composition (2) mineralogical composition (3) rock texture and (4) rock structure. Soils developed from calcium-aluminum rich rocks or from basic rocks which have structures or textures not conducive to good drainage are characterized by kaolin and montmorillonite clay minerals and by dense plastic, poorly drained, clayey subsoils. In all other soils and in the surface horizon of these soils, the major clay minerals are kaolin and vermiculite. Topography affects the degree of profile development, color, and soil texture and controls the rate of clay mineral accumulation and weathering. The climates of the Blue Ridge and Piedmont are most favorable to the formation of kaolin minerals. However, greater amounts of kaolinite appear to be formed in the warmer Piedmont climate and more vermiculite in the cooler Blue Ridge climate. The most important mechanism for clay mineral formation is probably by direct alteration of the primarily silicate minerals. The distribution of these clays in the profile is determined by the weathering stability of the primary silicate. All ferromagnesium silicates weather to 14 A clay minerals. An intermediate 14 A chlorite phase was not observed. The most common product is vermiculite. The formation of montmorillonite is controlled by the four parent material factors listed above. Hornblende and augite are the chief source materials of montmorillonite. Biotite possibly weathers to montmorillonite if the internal drainage is strongly retarded. Montmorillonite weathers to vermiculite in the surface horizons. Kaolinite forms early in the profile during the weathering of feldspar. Medium- to coarse-grained muscovite is also a source of kaolinite. There was no evidence found to indicate that kaolinite is a weathering product of the 12 A clay minerals. Illite occurs in minor amounts in a few micaceous profiles but appears to be the result of mechanical break-down of larger mica particles. / Master of Science

Call number: LD2668 .T4 1956 M35 / Master of Science