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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.
531

Strength of Concrete Masonry Prisms Constructed with Non-Traditional Grout and Type-M Mortar

Watterson, Scott Michael 09 December 2011 (has links) (PDF)
The Concrete Masonry Association of California and Nevada in conjunction with Brigham Young University devised a masonry prism testing scheme to aid in the determination of whether prisms constructed with grouts possessing high levels of supplemental cementitious materials could meet minimum masonry compressive strength requirements. ASTM standards, identical to that of concrete, place restrictions on quantities, by weight, of supplemental materials that can replace ordinary Portland cement. For an all fly ash replacement, up to 40% of Portland cement can be replaced while up to 70% can be replaced by a fly ash-slag combination. Research is focused on class F fly ash and ground granulated blast furnace slag replacing Portland cement in larger quantities. Manufacturing grouts with increasing incremental amounts help to establish higher use limitations associated specifically with masonry grout. Masonry prisms, concrete masonry units, type M mortar, and variations of grout were tested for their respective compressive strengths at age intervals of 14, 28, 42, 56, and 90 days. Grouts were designed to support the discussion of whether non-traditional grouts can achieve acceptable masonry compressive strength in prisms while not possessing adequate grout compressive strength. The control grout consisted of one mix design containing a cementitious materials content of 100% Portland cement. Three grouts replaced Portland cement with fly ash and three grouts replaced Portland cement with a fly ash-slag combination without modifying the cementitious material weight contribution. Class F fly ash replaced Portland cement at rates of 45%, 55%, and 65%. Class F fly ash-ground granulated blast furnace slag combinations replaced Portland cement at rates of 65%, 75%, and 85% where the combinations consisted of 25% fly ash and 40%, 50%, and 60% slag. Results indicate that all prisms exceeded the 10.3 MPa (1500 psi) minimum compressive strength requirements before the mandated 28-day age period. Neither 55% and 65% fly ash replacements nor the 85% fly ash-slag combination achieved grout strength minimums at the typical specified age. The grout mixtures manufactured with exceeding addition rates which attained greater than the minimum strength at the 28-day age were the 45% fly ash and 65% and 75% fly ash-slag combination. All grouts did, eventually, extend their strength gain beyond 13.8 MPa (2000 psi) through the course of testing and all but 65% fly ash achieved this strength within 42 days.
532

Utilization of Blow Flies (Phormia regina) as Vertebrate Resource Diversity Indicators

Ashton Brooke Jones (13150290) 08 September 2022 (has links)
<p>  </p> <p>Blow flies are often utilized in the field of forensic science due to their ability to aid in the estimation of time since death. Currently, estimations of postmortem interval require assumptions to be made and are prone to a margin of error, prompting research that may contribute to more accurate postmortem interval estimations and help to fill in the gaps of unknown information. Blow flies are necrophagous, feeding on feces and carrion, and therefore, are constantly sampling the environment. This behavior can be exploited in order to monitor the biodiversity in an environment. Through analysis of DNA isolated from the guts of blow flies, information can be obtained regarding what animals have died in an environment, what animals are still living in that environment, and the abundance and diversity of the animals present in a specific environment. Using fly-derived ingested DNA is a viable method for vertebrate resource identification and biodiversity monitoring. Over the course of a two-summer sampling period, in and around two national parks, a total of 162 blow fly (<em>Phormia regina</em>) samples returned a positive vertebrate DNA identification, with 33 species identified from five animal orders. Of the total number of flies collected and analyzed, 23.58% returned a positive vertebrate species identification. The method detected both abundant and common species based on National Park surveys, as well as some uncommon or unknown to the park species. In the SE region, 9 individuals belonging to the Rodentia order, 12 individuals belonging to the Artiodactyla order, 21 individuals belonging to the Carnivora order, 1 individual belonging to the Cingulata order, and 3 individuals belonging to the Lagomorph order were detected. In the SE region, 63% of the individuals detected belonged to the common category, 14% of the individuals detected belonged to the uncommon category, and 23% of the individuals detected belonged to the not in park/unknown category. In the NW region, 42 individuals belonging to the Rodentia order, 46 individuals belonging to the Artiodactyla order, and 28 individuals belonging to the Carnivora order were detected. In the NW region, 52% of the individuals detected belonged to the abundant category, 36% of the individuals detected belonged to the common category, and 12% of the individuals detected belonged to the uncommon category. The relative biodiversity of the sampled environment can be inferred. In the SE region, the Shannon Biodiversity Index was calculated to be 2.28 with an evenness of 0.844, while in the NW region, the Shannon Biodiversity Index was calculated to be 2.79 with an evenness of 0.855. Unsurprisingly, there was greater biodiversity in the Northwest Park samples than in the Southeast Park samples. Additionally, the ideal weather conditions for blow fly collection were determined be at a temperature of between 60- and 80-degrees Fahrenheit, a relative humidity between 50% and 60%, no precipitation, and a wind speed between 2 and 8 miles per hour. This information has further implications in the field of forensic science, specifically dealing with wildlife forensics, pathogen distributions, and can help to improve accuracy in regards to postmortem interval (PMI) estimations. </p> <p>  </p>
533

Drying shrinkage of self-compacting concrete incorporating fly ash

Abdalhmid, Jamila M.A. January 2019 (has links)
The present research is conducted to investigate long term (more than two years) free and confined drying shrinkage magnitude and behaviour of self-compacting concrete (SCC) and compare with normal concrete (NC). For all SCCs mixes, Portland cement was replaced with 0-60% of fly ash (FA), fine and coarse aggregates were kept constant at 890 kg/m3 and 780 kg/m3, respectively. Two different water binder ratios of 0.44 and 0.33 were examined for both SCCs and NCs. Fresh properties of SCCs such as filling ability, passing ability, viscosity and resistance to segregation and hardened properties such as compressive and flexural strengths, water absorption and density of SCCs and NCs were also determined. Experimental results of free drying shrinkage obtained from this study together with collected comprehensive database from different sources available in the literature were compared to five existing models, namely the ACI 209R-92 model, BSEN-92 model, ACI 209R-92 (Huo) model, B3 model, and GL2000 model. To assess the quality of predictive models, the influence of various parameters (compressive strength, cement content, water content and relative humidity) on the drying shrinkage strain are studied. An artificial neural network models (ANNM) for prediction of drying shrinkage strains of SCC was developed using the same data used in the existing models. Two ANNM sets namely ANNM1 and ANNM2 with different numbers of hidden layer neurones were constructed. Comparison between the results given by the ANNM1 model and the results obtained by the five existing predicted models were presented. The results showed that, using up to 60% of FA as cement replacement can produce SCC with a compressive strength as high as 30 MPa and low drying shrinkage strain. SCCs long-term drying shrinkage from 356 to 1000 days was higher than NCs. Concrete filled elliptical tubes (CFET) with self-compacting concrete containing FA up to 60% are recommended for use in construction in order to prevent confined drying strain. ACI 209R-92 model provided a better prediction of drying shrinkage compared with the other four models. However, a very high predictability with high accuracy was achieved with the ANNM1 model with a mean of 1.004. Moreover, by using ANNM models, it is easy to insert any of factors effecting drying shrinkage to the input parameters to predict drying shrinkage strain of SCC. / Ministry of Higher Education, Libya
534

Flow and Compressive Strength of Alkali-Activated Mortars.

Yang, Keun-Hyeok, Song, J-K., Lee, K-S., Ashour, Ashraf 01 January 2009 (has links)
yes / Test results of thirty six ground granulated blast-furnace slag (GGBS)-based mortars and eighteen fly ash (FA)-based mortars activated by sodium silicate and/or sodium hydroxide powders are presented. The main variables investigated were the mixing ratio of sodium oxide (Na2O) of the activators to source materials, water-to-binder ratio, and fine aggregate-to-binder ratio. Test results showed that GGBS based alkali-activated (AA) mortars exhibited much higher compressive strength but slightly less flow than FA based AA mortars for the same mixing condition. Feed-forward neural networks and simplified equations developed from nonlinear multiple regression analysis were proposed to evaluate the initial flow and 28-day compressive strength of AA mortars. The training and testing of neural networks, and calibration of the simplified equations were achieved using a comprehensive database of 82 test results of mortars activated by sodium silicate and sodium hydroxide powders. Compressive strength development of GGBS-based alkali-activated mortars was also estimated using the formula specified in ACI 209 calibrated against the collected database. Predictions obtained from the trained neural network or developed simplified equations were in good agreement with test results, though early strength of GGBS-based alkali-activated mortars was slightly overestimated by the proposed simplified equations.
535

"Let It Run"

Hyde, Spencer 08 1900 (has links)
Let It Run is the story of Oakley Isom, a neurotic, disturbed young woman stuck in a small town of two thousand people where she lives with her father, Waldemyre, a fly-fishing guide. Oakley works at the local newspaper as the editor of the "What's Biting?" section, something the fishermen live by. Oakley also works nights at a therapeutic boarding school for troubled youth. Entrenched in a world of self-loathing and obsessive thoughts, Oakley spends her time dreaming of a way out of Victor, Idaho. When a murder in the small town pulls Oakley into its eddy, she attempts to escape into her own compulsive thoughts, and the friendship of a striking young therapist at the boarding school. Unusual events continue to unfold, reeling Oakley in, and she must face a reality far more disturbing than a killer on the loose. Cosmic bottom line, the dissertation novel is about the issues of human identity, and if memory is fixed or dynamic, unified or multiple—and how readers deal with loss, guilt, and regret.
536

A proposed walkway system constructed from selected combustion residues

Hillabrand, James L 02 May 2009 (has links)
This thesis studies a new more affordable way to build sidewalks in the U.S. Typical sidewalks are often impractical on many roads because of a steep runoff slope and/or close proximity to the drainage ditch. Also, if future road widening is required, the sidewalk must be removed. This thesis proposes a structure called a Lanwalk which is an elevated sidewalk made of precast units. A Lanwalk could simultaneously serve as a sidewalk and potentially as a guardrail. It can be placed over drainage areas if necessary without obstructing the flow of water. Lanwalks can be easily installed and relocated if necessary. This thesis examines the possibility of using high amounts of waste ash as an admixture during the construction of Lanwalks or sidewalks to lower cost and save landfill space. The two waste products examined are municipal solid waste incinerator bottom ash (IBA) and coal fly ash (CFA).
537

Evaluating the Impact of Animated Topographic Fly-Throughs on Students’ Geographic Novelty Space During a Geology Field Trip

Hayes, James Curtis 25 July 2008 (has links)
No description available.
538

Structurally Integrated Embedded System

Zeppettella, David L. January 2011 (has links)
No description available.
539

VERIFICATION OF THE USE OF A CARBON BLOCKING AGENT FOR FLY ASH IN CONCRETE

TAYLOR, AARON THOMAS January 2007 (has links)
No description available.
540

Affect of Emission Controls on the Elemental Concentration and Particle Size of Coal Ash

Praechter, Todd A. 22 October 2013 (has links)
No description available.

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