ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
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- Creators: Mobasher, Barzin
The current method of measuring thermal conductivity requires flat plates. For most common civil engineering materials, creating or extracting such samples is difficult. A prototype thermal conductivity experiment had been developed at Arizona State University (ASU) to test cylindrical specimens but proved difficult for repeated testing. In this study, enhancements to both testing methods were made. Additionally, test results of cylindrical testing were correlated with the results from identical materials tested by the Guarded Hot&ndashPlate; method, which uses flat plate specimens. In validating the enhancements made to the Guarded Hot&ndashPlate; and Cylindrical Specimen methods, 23 tests were ran on five different materials. The percent difference shown for the Guarded Hot&ndashPlate; method was less than 1%. This gives strong evidence that the enhanced Guarded Hot-Plate apparatus in itself is now more accurate for measuring thermal conductivity. The correlation between the thermal conductivity values of the Guarded Hot&ndashPlate; to those of the enhanced Cylindrical Specimen method was excellent. The conventional concrete mixture, due to much higher thermal conductivity values compared to the other mixtures, yielded a P&ndashvalue; of 0.600 which provided confidence in the performance of the enhanced Cylindrical Specimen Apparatus. Several recommendations were made for the future implementation of both test methods. The work in this study fulfills the research community and industry desire for a more streamlined, cost effective, and inexpensive means to determine the thermal conductivity of various civil engineering materials.
The utilization of these materials has relied primarily on the dual benefits of reduced presence in landfills and cost. These have also proven to yield a higher service life as opposed to conventional ordinary portland cement (OPC) concrete due to an enhanced microstructure. The use of such materials however has not been readily acceptable due to detrimental early age behavior. The influence of design factors is studied to understand the reaction mechanism. Silicon polymerization at the molecular level is studied to understand the aluminosilicate interactions which are responsible for prevention of any leaching of ions. A comparative study between fly ash and slag binders is carried out to evaluate the stable states of sodium, aluminum and silicon in both these binders, since the likelihood of the sodium ions leaching out is high.
Compressive and flexural strength have been reported in previous literature, but the impact of crack resistance was unevaluated from an approach of characterizing the fracture process zone. Alternative routes of activation are explored with an intent to reduce the high alkalinity by use of neutral salts such as sodium sulfate. High volume OPC replacement by both class C and F fly ash is performed to evaluate the differences in hydration phase formation responsible for its pore refinement and strength. Spectroscopic studies have also allowed to study the fundamental material structure. Durability studies are also performed on these samples to understand the probability external sulfate attacks as opposed to OPC mixes.