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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Calcination of Marls to Produce Roman Cement

Hughes, David C., Jaglin, D., Kozlowski, R., Mayr, N., Mucha, D., Weber, J. January 2006 (has links)
no / Marls were identified from a range of European sources and assessed for their Cementation Index, as proposed by Eckel. Two were selected for calcination in a laboratory kiln; one from Folwark in Poland (CI 1.75) and one from Lillienfeld in Austria (CI 2.03). Analysis of historical documents, while not revealing precise kiln conditions, does suggest that they were such as not to yield complete decarbonation of the calcite. Consequently, a series of calcinations was undertaken in which the peak temperature control of the kiln was set in the range 730°C to 1100°C, with residence times in the range 150 to 1250 min. The airflow through the kiln was sufficient to maintain a minimum oxygen content of at least 12 %. The resulting clinker was ground to comply with the 19th century Austrian Norme. Pastes were produced at w/c = 0.65 and assessed for setting time and strength development (6 h to 1 year). Both parameters were highly dependent upon calcination conditions with both ¿low¿ and ¿high¿ calcinations producing slower setting and slower strength development than intermediate conditions. Two strength development profiles were identified; one being the expected continuous increase of strength, albeit with a declining rate of increase with time, while the other showed a three-step sequence of high initial strength, a dormant period which could last for many weeks and a final increase in strength to an age of one year. The cements were compared using X-ray diffraction (XRD). Considerable variation in the composition was noted and related to the calcination conditions. Of particular interest is the formation of both ¿'-belite and ß-belite under differing calcination conditions. Clinker particles were also compared using the SEM in back-scattered electron imaging mode and the development of morphology observed.
2

Hydrology of a large unstable hillslope at Ebnit, Vorarlberg : identifying dominating processes and structures

Lindenmaier, Falk January 2007 (has links)
The objective of this thesis is to improve the knowledge of control mechanisms of hydrological induced mass movements. To this end, detailed hydrological process studies and physically-based hydrological modelling were applied. The study site is a hillslope in the Dornbirn Ache valley near Bregenz, Austria. This so called Heumös slope features a deep-seated translational shear zone and surface near creep movements of up to 10 cm a year. The Cretaceous marlstones of the Austrian Helveticum have a high susceptibility for weathering and might form clay-rich cohesive sediments. In addition, glacial and post-glacial processes formed an unstable hillslope. High yearly precipitation depths of about 2100 mm and rainstorms with both high intensities and precipitation depths govern surface and subsurface hydrological processes. Pressure propagation induced in hydrological active areas influences laterally the groundwater reactions of the moving mass. A complex three-dimensional subsurface pressure system is the cause for fast groundwater reactions despite low hydraulic conductivities. To understand hillslope scale variability, hydrotopes representing specific dominating processes were mapped using vegetation association distribution and soil core analysis. Detailed small-scale soil investigations followed to refine the understanding of these hydrotopes. A perceptional model was developed from the hydrotope distribution and was corroborated by these detailed investigations. The moving hillslope is dominated by surface-runoff generation. Infiltration and deep percolation of water is inhibited through clay-rich gleysols; the yearly average soil moisture is close to saturation. Steep slopes adjacent to the moving hillslope are far more active concerning infiltration, preferential flow and groundwater fluctuations. Spring discharge observations at the toe of the steep slopes are in close relation to groundwater table observations on the moving hillslope body. Evidence of pressure propagation from the steep slopes towards the hillslope body is gathered by comparison of dominating structures and processes. The application of the physically-based hydrological model CATFLOW substantiates the idea of pressure propagation as a key process for groundwater reactions and as a possible trigger for movement in the hillslope. / Diese Arbeit soll die Zusammenhänge von hydrologischen Rahmenbedingungen und Massenbewegungen besser erforschen, damit in Zukunft verbesserte Vorhersagen des Versagenszeitpunktes möglich werden. Das Untersuchungsgebiet besteht aus einem ca. 2 km langen und 500 m breiten Hang mit einem maximalen Höhenunterschied von ca. 400 m. Das dort vorkommende Festgestein besteht im Wesentlichen aus Mergelstein. Die vergangenen Eiszeiten haben dieses Gestein überarbeitet und Grundmoränenablagerungen auf dem Hang zurückgelassen. Diese wurden in den letzen 10.000 Jahren von Hangschutt, der aus den benachbarten Steilhängen stammt, überlagert. Der Hangschutt ist sehr verwitterungsanfällig, die Kalkkristalle lösen sich und wandeln den Hangschutt in lehmiges Material. Bewegungsmessungen an der Oberfläche zeigen, dass sich der Hang mit ca. 10 cm im Jahr talabwärts bewegt. Diese Bewegungen werden sehr wahrscheinlich durch kleine ruckartige Ereignisse in ca. 8 m Tiefe ausgelöst. Ziel der Untersuchungen war, den Wasserhaushalt des Hanges so gut wie möglich zu erfassen und mit Computermodellen abzubilden. Dabei spielt die Heterogenität der pedologischen Eigenschaften einen wesentliche Rolle, als Eingangsparameter für die Modelle. Grundwasserstandsmessungen in 5,5 m Tiefe auf dem Hang zeigen schnelle Reaktionen des Grundwasserspiegels nach Niederschlagsereignissen. Das Wasser dieser Ereignisse kann aber aufgrund des Lehms, der nur eine geringe Wasserdurchlässigkeit für Wasser besitzt, nicht in den tieferen Untergrund gelangen, sondern fließt fast vollständig an der Oberfläche ab. Dahingegen führt ein schnelles Versickern von Wasser in an den Hang anschließenden Steilhängen zu einem schnellen Grundwasseranstieg, der aufgrund eines gespannten Grundwasserleiters den Druck in die Hangrutschung weitergibt. Dort wird ein Überdruck aufgebaut, der sehr wahrscheinlich die Bewegungen auslöst. Die vorliegende Arbeit ist eine detaillierte Herangehensweise um Erkenntnisse aus der Hyrologie für die Bestimmung des Wasserhaushaltes von Massenbewegungen heranzuziehen.
3

Edimentology And Stratigraphy Of Turbeyani Marl Sequences And Inpiri Limestones (late Barremian - Albian): Implications For Possible Source And Reservoir Rocks (nw Turkey)

Nabiyev, Anar 01 April 2007 (has links) (PDF)
SEDIMENTOLOGY AND STRATIGRAPHY OF T&Uuml / RBEYANI MARL SEQUENCES AND iNPiRi LIMESTONES (LATE BARREMIAN - ALBIAN): IMPLICATIONS FOR POSSIBLE SOURCE AND RESERVOIR ROCKS (NW TURKEY) Anar Nabiyev M.Sc., Department of Geological Engineering Supervisor: Assist. Prof. Dr. i. &Ouml / mer Yilmaz April 2007, 105 pages Sedimentology, cyclostratigraphy and sequence stratigraphy of the T&uuml / rbeyani Marls (Albian) and the inpiri Limestone (Upper Barremian-Albian) members of Ulus Formation (incigez, Bartin, Amasra) were interpreted in this study. In the T&uuml / rbeyani Marls total of five different facies were defined. Marl and limestone facies are the most abundant in the succession. The depositional environment of the succession was defined as an outer shelf area. Within the pelagic marls 39 smaller order and 9 higher order cycles were recognized. These cycles correspond to the parasequences and parasequence sets of sequence stratigraphy, respectively. In the measured section only one type-3 sequence boundary was identified. In the inpiri Limestones great variety of limestone facies are represented. Bioclastic, peloidal, intraclastic wackestone-packstone-grainstone facies are the most abundant. Moreover, occurrence of lime mudstone, fenestral limestone, ooid packstone-grainstone, and sandstone facies are present as well. In the measured section of the inpiri Limestones 25 fifth order and 6 fourth order cycles were defined. These cycles correspond to the parasequence sets and systems tracts of the sequence stratigraphy, respectively. Total of three transgressive and three highstand systems tract were defined. Only one type 2 sequence boundary was identified in the measured section, the rest of them are interrupted by covers. This study revealed that the T&uuml / rbeyani Marls and the inpiri Limestones are not economically valuable as petroleum source and reservoir rocks, respectively. The total organic carbon (TOC) values of marl facies of the T&uuml / rbeyani marls are very low, and the pore spaces observed in the inpiri Limestone are cement filled making it unsuitable reservoir rock. Keywords: sedimentology, cyclostratigraphy, sequence stratigraphy, T&uuml / rbeyani Marls, inpiri Limestones, Albian, Upper Barremian, Amasra, Bartin.

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