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Microstructure, Quasi-Static, And High-Strain Rate Dynamic Characterization Of Metakaolin And Fly Ash Based Geopolymers For Structural Applications, Damian Lee Stoddard Jan 2014

Microstructure, Quasi-Static, And High-Strain Rate Dynamic Characterization Of Metakaolin And Fly Ash Based Geopolymers For Structural Applications, Damian Lee Stoddard

Electronic Theses and Dissertations

Geopolymers are a class of rapid setting cementing systems that have been used as mortar or additives in concrete mixes to improve properties. Several types of geopolymer systems such as metakaolin and fly ash based geopolymers are widely used, and are available in different mixture proportions [1, 2]. Metakaolin (Al2Si2O7), a dehydroxylated form of Kaolinite (Al2Si2O5(OH)4) clay readily available from many sources, provides several benefits whenadded to a concrete mix design or used as a mortar system, including durability, freeze/thaw, acid resistance, and high temperature resistance [3]. Class F fly ash-based mortar geopolymers provide added fire retardation, reduces crack formation, …


Optimization Of Wind Fence Enclosures For Infrasonic Wind Noise Reduction, Johnpaul Russell Abbott Jan 2014

Optimization Of Wind Fence Enclosures For Infrasonic Wind Noise Reduction, Johnpaul Russell Abbott

Electronic Theses and Dissertations

A large porous wind barrier enclosure has been built and tested to optimize wind noise reduction at infrasonic frequencies between 0.01-10 Hz in order to develop a technology that is simple, cost effective, and improves upon the limitations of pipe and porous hose arrays. The effects of varying the fence's porosity, modifying its top condition and bottom gap, doubling the height and diameter, and adding a secondary wind barrier were investigated. A simple mathematical model which estimates the wind noise measured at the center of the enclosure was derived based on the measured turbulence and velocity profiles measure outside the …


Finite Element Analysis Of Shear Resistant Mechanisms For Biolaminate Interfaces, Matthew Nelms Jan 2014

Finite Element Analysis Of Shear Resistant Mechanisms For Biolaminate Interfaces, Matthew Nelms

Electronic Theses and Dissertations

The Alligator gar possesses a flexible dermal armor consisting of overlapping ganoid scales. Each scale is a bilayer hydroxyapatite and collagen-based bio-laminate for protection against predation. The exoskeleton fish scale is comprised of a stiff outer ganoine layer, a characteristic "sawtooth" pattern at the interface and a compliant bone inner layer with all materials exhibiting a decreasing elastic modulus, yield strength and density through the thickness. Experiments on ganoid scales revealed properties such as damage mitigation and energy dissipation that are unique to biological dermal armor. The objective of this investigation is to develop a fundamental understanding of the stress …