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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.
181

Portland Limestone Cement with Fly Ash: Freeze-Thaw Durability and Microstructure Studies

Angadi, Prokshit January 2018 (has links)
In this study, the freeze-thaw performance and other engineering properties of different cementitious mixtures containing Type I/II portland cement, Type IL (10) portland Limestone cement (PLC) and Coarse Ground cement (CG-P) with or without partial replacement of fly ash (Class F) were examined. The goal was to develop a concrete mixture with better or similar freeze-thaw durability without adversely affecting other engineering properties of concrete. Crucial engineering properties reviewed include compressive strength, splitting tensile strength, workability, the degree of hydration, setting time, shrinkage and resistivity. The study was divided into two parts, one consisting of mechanical testing of engineering properties including the freeze-thaw test. The second part consisted of microstructure study which involved detection and quantification of micro-cracks/defects using μ-CT and fluorescence microscopy. The results showed that the portland limestone cement in combination with fly ash demonstrated better or similar durability in comparison to the conventional portland cement concrete mixtures.
182

Awaiting water

Nordblad, Sofia January 2022 (has links)
There is a limestone quarry on Öland that was active between 1888 and 2019.  Now that Cementa has ceased mining, the quarry is about to be naturally flooded with rainwater and infiltrating groundwater. In 20 years from now, the water level will be 5 meters higher than today.  As a final proposal I present a multifunctional visitor’s center placed on a peninsula that will eventually transform into an island. The quarry is popular amongst birds and the observation tower makes it possible to study them closely. The exhibition hall can show work from Öland’s many artists and the flexible square can host everything from yoga classes to dance nights. A small kiosk sells ice cream and sandwiches. The changing booths, lockers, restrooms and saunas enable you to enjoy this place in every season, protected from the sometimes very rough elements that is Öland’s signature. For each year the water level will rise and create a new experience, even for returning visitors. When the surface has reached its highest point in the 2040’s, the center will appear floating on the water surface and welcome you on a path framed with casted stone walls pushing the water aside.
183

Geology of the Summer Ranch and North Promontory Mountains, Utah

Adams, O. Clair 01 May 1962 (has links)
General Statement The Summer Ranch and North Promontory Mountains have not been studied in detail geologically, although the surrounding mountains have been extensively investigated. Within the limits of this area, sedimentary rocks of Mississippian through Permian crop out. Sedimentary and volcanic rocks of Tertiary age are also exposed. Extensive Lake Bonneville deposits underlie the valleys and overlap the foothills. The purposes of this study are: (1) to describe the structure, stratigraphy, and geologic history of the area, (2) to prepare a geologic map of the area, and (3) to relate the stratigraphic features of this area to those of the surrounding region. Location of Area The area studied is bordered on the north by the Utah-Idaho state line and on the east by Blue Creek Valley. Utah State Highway 83 and Great Salt Lake form the southern boundary and Curlew Valley, south-southwest from Snowville, Utah, defines the western limit (Figure 1). The mapped area lies completely .within Box Elder County and covers a total of about 529 square miles. The Utah division of the Thiokol Chemical Corporation is located near the southeast corner of the mapped area. Field Work Initial field work was begun in August of 1960. Investigation of the 3 mapped area plus near-by areas was carried on continuously through September of that year and intermittently until June, 1961. Access roads are mainly unimproved but are passable by passenger car. Water is available at most of the ranches in the adjoining valleys and at several springs in the North Promontory and Summer Ranch Mountains. Structural and stratigraphic details were plotted on vertical aerial photographs in the field. Information was subsequently transferred to a topographic map at a scale of 1:62, 500, which was enlarged from a U. S. Geological Survey map, then traced on a transparent overlay. Stratigraphic sections were measured with a Brunton compass or with a steel tape. Previous Investigations No previous complete geologic investigation has been made of the area covered by this report. Various local features within the mapped area have been studied. Walter (1934, p. 178-195) describes the structural relations of the Hansel Valley earthquake of 1934. Additional investigation concerning the structure of Hansel Valley was conducted by Adams (1938). Tertiary stratigraphy of Cache Valley was studied by Adamson (1955). Adamson reported the occurrence of tuffaceous rocks, similar to those in Cache Valley, in association with basalt flows near Snowville, Utah. Smith (1953, p. 74) diagrams the southern limit of the Snake River basalt flows and showed that they covered the northern part of the area concerned in the present investigation.
184

Evaluation of and design considerations for drilled shafts socketed into coral and coquina limestones

Semeraro, Michael Archangel January 1982 (has links)
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 161-168. / by Michael Archangel Semeraro, Jr. / M.S.
185

Effects of Thermally-Induced Microcracking on the Quasi-Static and Dynamic Response of Salem Limestone

Crosby, Z Kyle 11 May 2013 (has links)
The effects of microcracking on the mechanical properties of Salem limestone were investigated in three phases: introduction of quantifiable levels of microcracks by thermal treating, mechanical testing of limestone samples with varying levels of microcracks, and modification of a numerical model to incorporate the measured effects. This work demonstrated that this approach is useful for examination of the effects of microcracking on quasi-brittle materials and can be used to improve the predictive capabilities of material models. Thermal treating was found to consistently induce quantifiable levels of microcracks in Salem limestone. Sonic wave velocities indicated that the induced microstructural changes were a function of the maximum temperature. The wave velocities showed little variability demonstrating the effectiveness of the approach for inducing consistent levels of microcracking. X-ray diffraction, differential scanning calorimetry, and thermogravimetric analysis confirmed that no composition changes occurred for the temperature range of interest. Computed tomography scanning, scanning electron microscopy, and optical microscopy (OM) were used to observe microstructural changes caused by the heat treatments. OM analysis was the primary method used in the microcrack characterization and yielding qualitative and quantitative data. OM images showed an increase in grain boundary and intragranular cracking with increasing maximum heat treatment temperatures. Stereological evaluation provided microcrack data indicating that microcrack density increased as function of the maximum heat treatment temperatures. Mechanical testing was performed to characterize the mechanical response of the intact and damaged limestone. Quasi-static tests included uniaxial compression, triaxial compression, hydrostatic compression, and uniaxial strain / constant volume tests. Microcracking did not affect the limestone’s strength at pressures greater than 10 MPa. Dynamic tests were performed using a modified split Hopkinson pressure bar. Microcracking did not have an effect on the dynamic strength of the limestone. The results of the mechanical tests were used to modify the HJC model. Modifications were made to account for shear modulus degradation and failure surface changes. The original and modified HJC models were used in a numerical analysis of the mechanical tests performed in this work. The modified HJC provided better results for damaged material when compared with the quasi-static and dynamic experiments.
186

Sequence Stratigraphy and Paleoecology of the Late Mississippian Little Stone Gap Member in the Appalachians of West Virginia

Oyewumi, Adeola Adedoyin 12 June 2012 (has links)
The upper Mississippian (Chesterian) Little Stone Gap Member of the Hinton Formation in southern West Virginia was evaluated for its lithofacies and faunal composition. Petrographic and multivariate analyses were used to provide a better understanding of the ecological factors and sequence stratigraphic processes that controlled taxa ordinations and spatiotemporal shifts in facies. Six carbonate and three siliciclastic facies occur within the study interval and these facies stack into two distinct parasequence types. Siliciclastic facies were deposited in continental, low-energy lagoonal and marginal marine environments. Carbonate facies record variable energy conditions in lagoonal, shoal, shoal flank and open marine settings. Parasequence stacking patterns are interpreted as resulting from regional fifth-order glacioeustatic sea-level changes consistent with established age constraints for fourth-order sequences. Detrended Correspondence Analysis (DCA) of paleontological bulk samples produced similar differentiation of habitats into carbonates and siliciclastics thereby demonstrating the importance of interpreting ordination patterns within a facies framework. The combined DCA analysis of samples and taxa indicates that bryozoans, crinoids and rugose corals preferentially occur in carbonate facies whereas brachiopods, the most dominant taxon, are abundant in both. Results suggest the presence of significant paleoenvironmental gradients in fossil associations that correlates to changes in hydrodynamic conditions and substrate composition across the depositional system. / Master of Science
187

Microstructures and Deformation in Some Fault Rocks From The McConnell Thrust at Mount Yamnuska (Alberta) : Implications for Fluid Flow and Faulting and Cycles of Strain-Hardening and Softening

Miyagi, Lowell January 2004 (has links)
No description available.
188

Feasibility Analysis of the Strontium Ratio Obtained from Pennsylvanian Chondricthian Dentary

Erbacher, Cullen John 11 December 2006 (has links)
No description available.
189

Low-temperature dry scrubbing reaction kinetics and mechanisms: Limestone dissolution and solubility

Maldei, Michael January 1993 (has links)
No description available.
190

Characterization of a highly acid watershed located mainly in Perry County, Ohio

Eberhart, Ryan J. January 1998 (has links)
No description available.

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