Inaug.-Diss.-Munich. / Reprinted from Neues Jahrbuch für Mineralogie ... Beilageband XV, 1902. Bibliography: p. 231-243.

With the aim to achieve a better understanding of the time-dependent behaviour of structured clays, especially cemented clay, a critical review of the literature and a programme of laboratory testing have been carried out. In order to investigate the time effects on different structured clays, a series of advanced triaxial and oedometer tests were conducted on reconstituted pure kaolin (PK), artificially cemented kaolin (ACK) with different curing periods, and remoulded artificially cemented kaolin (RACK). Strain rate effects were examined in pure kaolin with different degrees of over-consolidation in both undrained and drained shearing. The influence of bond structure on the monotonic stress-strain behaviour of cemented kaolin was investigated on specimens prepared with two different curing stress and curing periods. Tests on pure kaolin and remoulded cemented kaolin were also performed. Strain rate effects on long cured cemented kaolin under low and high confining stresses, with constant rate of straining in pre-peak stage and step-wise change rate of straining in post-peak stage were examined. This was completed by a study of the microstructure of pure kaolin and cemented kaolin specimens before and after tests via scanning electronic microscope. The coupling between stress or strain rate and curing time effects was investigated on cemented kaolin cured for shorter periods. The results have added significant data to the existing database and addressed the relationship between bond structure and time effect. The main conclusions are: ••The viscous type of PK determined is characterized as decaying positive isotache and General TESRA in undrained and drained shearing repectively. The strain rate history does not affect the critical state in both q-p’ and v-ln p’ spaces. ••The addition of cement not only creates new inter-particle bonds but also affects new fabric. The shear strength is dominated by bond structure under low confining stress, and by volume change under high confining stress. ••The viscous type of long-term cured ACK is dependent on the degree of bond structure. It is almost insensitive to strain rate changes when the specimen is stiff, and the apparent “aging” effect dominates resulting in a “negative” rate effect when bond structure is destroyed. A special rate phenomenon called stick-slip seems to occur under the lowest strain rate (0.01%/h) during the pre-peak stage. The RACK shows a TESRA type of viscosity in undrained shearing. ••The short-term cured ACK, in which structuring and rate effects are combined, shows negative rate effects due to the curing under low confining stress and apparent aging under high confining stress. Stick-slip occurs both in pre-peak and post-peak stages, due to different reasons. / published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

Inaug.-Diss.-Munich. / Reprinted from Neues Jahrbuch für Mineralogie ... Beilageband XV, 1902. Bibliography: p. 231-243.

Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1934. / The entire thesis text is included in file. Typescript. Illustrated by author. Title from title screen of thesis/dissertation PDF file (viewed June 9, 2010) Includes bibliographical references (p. 14) and abstracts (p. 15-16).

Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1929. / The entire thesis text is included in file. Typescript. Illustrated by author. Title from title screen of thesis/dissertation PDF file (viewed October 29, 2009) Includes bibliographical references (p. 15).

Th.--Sci. phys.--Nancy--I.N.P.L., 1977.

Silica sand (SS) samples from the Hanout area of Late Cambrian-Early Ordovician sandstone and the kaolinitic sandstone (KS) samples from the Wadi Es Siq-Rakyia area of Lower Cretaceous in south of Jordan were studied and assessed as a source of glass sand. A detailed mineralogical, geochemical, and grain size distribution analysis was carried out using XRD, XRF, SEM, and binocular microscopy. Heavy mineral separation was conducted using heavy liquids and spirals. Attrition scrubbing trials were performed on various size fractions to assess the benefit of attrition scrubbing in upgrading the silica sand. Upgrading the silica sand included removing or reducing the content of the contaminant oxides (i.e., Al2O3, Fe2O3, TiO2, CaO, and MgO) and the heavy minerals. The aim of this project was to achieve this upgrading through the use of inexpensive and relatively simple processing techniques. Kaolin was also concentrated in the fine fraction after attrition scrubbing and wet screening of the kaolinitic sandstone sample. Following the initial sample characterisation at “bench scale”, a pilot plant study was performed on bulk samples of both the silica sand and the kaolinitic sandstone. A high-grade glass sand product of 500-125μm size fraction was produced from both samples by dry and wet screening, attrition scrubbing and the separation of heavy minerals using spirals. Due to the relatively low level of impurities in the raw material, a high silica sand recovery was produced with a high silica grade when the middling fraction was combined with that of the product fraction. The mass flowrate of the feeds and the products in the spiral was calculated for both SS and KS samples as well as in the hydrocyclones for the – 125μm fraction of the KS sample. The amount of water required to operate the pilot plant was calculated. The high quality glass sand produced compared well with the Grade A British Standard for glass sand. The silica sand product was clearly capable of being used in the high quality glass industry and in many other applications where pure silica is required. A kaolin-enriched product was produced from the –125μm wet screened fraction of the kaolinitic sandstone following the use of small diameter hydrocyclones. A moderate quality of kaolin with low recovery was produced from the KS sample, which could be used in the ceramic industry for tableware and sanitaryware.

No description available.

Mémoire (M.Sc.T.) -- Université du Québec à Chicoutimi, 1986. / Document électronique également accessible en format PDF. CaQCU

Texte remanié de: Th.--Sci. nat.--Université de Strasbourg I, 1983. / Bibliogr. p. 299-306.