Current Search: Addition (x)
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Title
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Nanotechology in concrete: review and statistical analysis.
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Creator
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Glenn, Jonathan., College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
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Abstract/Description
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This thesis investigates the use of nanotechnology in an extensive literature search in the field of cement and concrete. A summary is presented. The research was divided into two categories: (1) nanoparticles and (2) nanofibers and nanotubes. The successes and challenges of each category is documented in this thesis. The data from the literature search is taken and analyzed using statistical prediction by the use of the Monte Carlo and Bayesian methods. It shows how statistical prediction...
Show moreThis thesis investigates the use of nanotechnology in an extensive literature search in the field of cement and concrete. A summary is presented. The research was divided into two categories: (1) nanoparticles and (2) nanofibers and nanotubes. The successes and challenges of each category is documented in this thesis. The data from the literature search is taken and analyzed using statistical prediction by the use of the Monte Carlo and Bayesian methods. It shows how statistical prediction can be used to analyze patterns and trends and also discover optimal additive dosages for concrete mixes.
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Date Issued
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2013
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PURL
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http://purl.flvc.org/fcla/dt/3360786
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Subject Headings
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Nanostructured materials, Nanofibers, Cement, Additives, Concrete, Additives
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Format
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Document (PDF)
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Title
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Developmental and contextual effects on children's addition strategies.
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Creator
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Rosenblum, Kristina E., Florida Atlantic University, Bjorklund, David F.
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Abstract/Description
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Developmental and contextual effects on children's addition strategies were assessed in two experiments. The first experiment examined developmental differences in preschool, kindergarten, and first grade children's strategy use during a nonschool-related task, a board game. The children showed a developmental progression in their strategy use during the game as would be predicted by Siegler's strategy-choice model, with children overall showing multiple and variable strategy use, and a...
Show moreDevelopmental and contextual effects on children's addition strategies were assessed in two experiments. The first experiment examined developmental differences in preschool, kindergarten, and first grade children's strategy use during a nonschool-related task, a board game. The children showed a developmental progression in their strategy use during the game as would be predicted by Siegler's strategy-choice model, with children overall showing multiple and variable strategy use, and a progression toward more sophisticated strategy use with age. The second experiment compared the game context with a comparable school-related math context in first graders. Three testing sessions separated by about a week, included the game, aural math problems, and a series of diagnostics designed to measure verbal IQ and working memory. The children showed great variability in their strategy use between the two contexts and were faster and more accurate during the game. Within each context, verbal IQ and working memory displayed some interesting relationships with strategy use.
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Date Issued
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1997
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PURL
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http://purl.flvc.org/fcla/dt/15409
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Subject Headings
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Number concept in children, Mathematical ability, Addition
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Format
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Document (PDF)
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Title
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Influence of pozzolanic admixtures on concrete pore water pH, chloride diffusion and chloride binding.
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Creator
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Charvin, Stephanie., Florida Atlantic University, Hartt, William H.
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Abstract/Description
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This report describes the results obtained from reinforced concrete slabs having different fly ash and silica fume content. The specimens are submitted to periodic seawater ponding. PH measurements as well as free and total chloride analyses were achieved at 1213 days in order to study the alkalinity, resistance to chloride ingress and binding properties afforded by each mix design. Water absorption experiments were also conducted at different relative humidities and in water. Pore water pH...
Show moreThis report describes the results obtained from reinforced concrete slabs having different fly ash and silica fume content. The specimens are submitted to periodic seawater ponding. PH measurements as well as free and total chloride analyses were achieved at 1213 days in order to study the alkalinity, resistance to chloride ingress and binding properties afforded by each mix design. Water absorption experiments were also conducted at different relative humidities and in water. Pore water pH was found to decrease with increasing admixture content and increasing relative humidity. The permeability to chloride ions was significantly reduced in the fly ash blends whereas most of the silica fume blends exhibited effective diffusion coefficients and chloride concentrations at the depth of steel marginally better than the controls. Both the fly ash and silica fume blends showed similar binding capacity at a given replacement ratio, the percentage of bound chloride increasing with increasing admixture content.
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Date Issued
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1999
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PURL
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http://purl.flvc.org/fcla/dt/15664
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Subject Headings
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Reinforced concrete construction--Corrosion, Concrete--Additives
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Format
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Document (PDF)
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Title
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Accelerated curing of concrete with high volume pozzolans - resistivity, diffusivity and compressive strength.
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Creator
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Liu, Yanbo., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
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Abstract/Description
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This investigation presents results of the temperature effect on durability properties (resistivity and diffusivity) and compressive strength of concrete with pozzolans, and the effect of pozzolanic admixtures on microstructure and chemical compositions of concrete pore solution. ... Temperature dependence of electrical resistivity and chloride diffusivity was studied by dynamic temperature tests. Accelerated curing regimes involving curing concrete specimens in 35À C lime water with...
Show moreThis investigation presents results of the temperature effect on durability properties (resistivity and diffusivity) and compressive strength of concrete with pozzolans, and the effect of pozzolanic admixtures on microstructure and chemical compositions of concrete pore solution. ... Temperature dependence of electrical resistivity and chloride diffusivity was studied by dynamic temperature tests. Accelerated curing regimes involving curing concrete specimens in 35À C lime water with different durations were tested. Compressive strength test, resisivity measurement and rapid chloride migration (RCM) tests were performed. A leaching method was used to measure pH and conductivity of concrete pore solution. ... The accelerated curing regimes were found to increase the compressive strength and resistance to chloride ion penetration at short-term and long-term. With the developed correlation between resistivity and migration coefficients, it is possible to employ the resistivity measurement as an alternative or replacement of the RCM test to evaluate resistance of chloride ion penetration of concrete. Pozzolanic admixtures were found to decrease both pH and conductivity of concrete pore solution as the replacement ratio increased. Moreover, the migration coefficients were found to be greatly correlated to the microstructure properties of concrete, such as porosity, formation factor and tortuosity.
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Date Issued
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2012
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PURL
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http://purl.flvc.org/FAU/3358603
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Subject Headings
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Pavements, Concrete, Additives, Quality control, Waste products as road materials, Reinforced concrete, Corrosion, Testing
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Format
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Document (PDF)
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Title
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Use of hybrid Rice Husk Ash-Fly Ash mixtures as sustainable supplementary materials for concrete in the marine environment.
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Creator
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Arboleda, Diana., College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
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Abstract/Description
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This paper presents the comparison of shrinkage and corrosion characteristics of optimized hybrid Rice Husk Ash (RHA)/Fly Ash (FA)-modified Concrete, with those of normal concrete in the marine environment. Uses of both FA and RHA have numerous environmental benefits. Shrinkage performance was determined by subjecting the mixes to restrained shrinkage testing per ASTM C1581. The time to cracking of the specimens improved an average of 18% with the hybrid mixes. Corrosion testing of reinforced...
Show moreThis paper presents the comparison of shrinkage and corrosion characteristics of optimized hybrid Rice Husk Ash (RHA)/Fly Ash (FA)-modified Concrete, with those of normal concrete in the marine environment. Uses of both FA and RHA have numerous environmental benefits. Shrinkage performance was determined by subjecting the mixes to restrained shrinkage testing per ASTM C1581. The time to cracking of the specimens improved an average of 18% with the hybrid mixes. Corrosion testing of reinforced columns was performed in a simulated tidal cycle Marine Environment. Corrosion potential improved by as much as 35% for the mix with the highest FA/RHA replacement, and corrosion activity as measured with potentiostat equipment improved by an average of 34% . These results indicate a clear performance improvement of the modified concrete that is proportional to the percent replacement of cement.
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Date Issued
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2010
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PURL
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http://purl.flvc.org/FAU/2138109
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Subject Headings
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Fracture mechanics, Concrete, Additives, Testing, Fly ash, Testing, Concrete, Cracking, Prevention, Industrial minerals, Testing
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Format
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Document (PDF)
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Title
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Performance characteristics of coal fly ash and wood ash-modified asphalt binder.
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Creator
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Butul, Boris., Florida Atlantic University, Reddy, Dronnadula V.
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Abstract/Description
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Coal fly ash and wood ash were added singly to asphalt mixes as partial replacements of the asphalt cement. Mechanical property testing and cost analysis were carried out with the following percentages: 0, 10, 15, 20, and 25. The objective of the investigation was to determine the changes in mechanical properties and cost-effectiveness of ash modification. The softening point, penetration, creep displacement, and modulus of elasticity indicated stiffening of the mix with increased ash...
Show moreCoal fly ash and wood ash were added singly to asphalt mixes as partial replacements of the asphalt cement. Mechanical property testing and cost analysis were carried out with the following percentages: 0, 10, 15, 20, and 25. The objective of the investigation was to determine the changes in mechanical properties and cost-effectiveness of ash modification. The softening point, penetration, creep displacement, and modulus of elasticity indicated stiffening of the mix with increased ash proportion. The indirect tensile and compression strengths reached peak values for the 10 and 15% mixes. The Marshall stability, the bulk density, and the maximum density, decreased with ash addition. The cost analysis indicated a saving of 6% for ash replacement of 15%. Therefore, the replacement of 10 to 15% of asphalt cement is an excellent solution to decrease the mix costs and to reduce the amount of ash in landfills without compromising the mechanical properties of the mix.
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Date Issued
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2000
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PURL
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http://purl.flvc.org/fcla/dt/12674
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Subject Headings
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Coal ash, Fly ash, Waste products as road materials, Asphalt cement--Additives
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Format
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Document (PDF)
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Title
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Obstruction of chloride diffusion in concrete by embedded reinforcing bars.
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Creator
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Cros, Pascal., Florida Atlantic University, Hartt, William H.
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Abstract/Description
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A study was performed of the effect of reinforcing bars on chloride diffusion into concrete. These bars act as obstacles to chloride movement, and this obstruction allows the chloride concentration to build-up faster along the top of the reinforcing bar than elsewhere. As a consequence, the critical chloride threshold to initiate corrosion of the steel is reached sooner than otherwise expected. This research was performed using two different methods. First, chloride analyses were performed on...
Show moreA study was performed of the effect of reinforcing bars on chloride diffusion into concrete. These bars act as obstacles to chloride movement, and this obstruction allows the chloride concentration to build-up faster along the top of the reinforcing bar than elsewhere. As a consequence, the critical chloride threshold to initiate corrosion of the steel is reached sooner than otherwise expected. This research was performed using two different methods. First, chloride analyses were performed on chloride exposed concrete blocks by taking cores in the concrete and drillings along the trace of the top bars. Second, concrete blocks models were analyzed by finite element analysis and the effect of the obstruction by the bar quantified. The role of the reinforcing bar in the chloride diffusional flow is discussed considering these two methods.
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Date Issued
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2005
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PURL
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http://purl.flvc.org/fcla/dt/13239
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Subject Headings
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Reinforcing bars--Corrosion, Reinforced concrete construction--Corrosion, Concrete--Additives, Chlorides--Diffusion rate
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Format
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Document (PDF)
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Title
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An Experimental Evaluation of High Volume Fly Ash Structural Concrete made from Recycled Aggregate.
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Creator
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Theodorou, Anthony Lloyd, Sobhan, Khaled, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
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Abstract/Description
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Three vital factors, namely environmental protection, savings in costs, and strength/durability benefits, make it advantageous to incorporate fly ash of controlled quality and composition in all concrete made from construction demolition (C&D) recycled aggregate. The specific objective of this research was to compare the performance characteristics of High-Volume-Fly-Ash (HVFA) structural concrete containing C&D aggregate with that of normal recycled aggregate concrete containing no fly ash....
Show moreThree vital factors, namely environmental protection, savings in costs, and strength/durability benefits, make it advantageous to incorporate fly ash of controlled quality and composition in all concrete made from construction demolition (C&D) recycled aggregate. The specific objective of this research was to compare the performance characteristics of High-Volume-Fly-Ash (HVFA) structural concrete containing C&D aggregate with that of normal recycled aggregate concrete containing no fly ash. A coordinated experimental program was undertaken which comprised of ( 1) Compressive and Split Tensile strength tests; (2) ASTM durability tests by measuring resistance to chloride-ion penetration; and (3) Flexural strength tests on reinforced concrete beam specimens. Three mix designs were used, all of which had the same water/cement ratio of 0.45 and the same amount of recycled aggregate/yd^3. Mix 1 contained cement and no fly ash, Mix 2 contained 16% replacement of cement by weight, and Mix 3 contained 40% replacement of cement, called a HVF A mix. Results indicate that fly ash increases compressive strength, improves both moment carrying capacity and tension resistance, and increases resistance to chloride-ion attack.
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Date Issued
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2008
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PURL
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http://purl.flvc.org/fau/fd/FA00012563
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Subject Headings
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Aggregates (Building materials)--Recycling, Fly ash--Recycling, Concrete--Additives--Evaluation, Concrete--Permeability, Industrial minerals--Evaluation
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Format
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Document (PDF)
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Title
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Strength and Durability of Rice Husk Ash-Modified Concrete in the Marine Environment.
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Creator
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Alvarez, Marcelina, Reddy, Dronnadula V., Florida Atlantic University
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Abstract/Description
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The purpose of this research project is to compare the strength and durability characteristics of rice husk ash-modified concrete with those of normal concrete in the marine environment. Specimens prepared from concrete mixes with watercementitious ratios of 0.40 and 0.55, and rice husk ash content of 0%, 10%, and 20% were tested. The rice husk ash used was obtained from Agrilectric, power plant located in Lake Charles, Louisiana. The grinding of the ash to particle size of 7-J..tm to 45-J....
Show moreThe purpose of this research project is to compare the strength and durability characteristics of rice husk ash-modified concrete with those of normal concrete in the marine environment. Specimens prepared from concrete mixes with watercementitious ratios of 0.40 and 0.55, and rice husk ash content of 0%, 10%, and 20% were tested. The rice husk ash used was obtained from Agrilectric, power plant located in Lake Charles, Louisiana. The grinding of the ash to particle size of 7-J..tm to 45-J..tm was done by Process Research ORTECH Inc., Ontario, Canada. Strength and durability tests were performed, following ASTM (American Society for Testing and Materials) Standards. The significant fmdings are that the properties and quality of the rice husk ash-modified concrete are as good, if not better than normal concrete.
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Date Issued
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2006
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PURL
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http://purl.flvc.org/fau/fd/FA00012502
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Subject Headings
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Seawater corrosion, Reinforced concrete--Environmental testing, Concrete--Additives, Rice hulls--Testing, Limekilns--Testing
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Format
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Document (PDF)
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Title
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How regulation fuels consumption of ethanol: a spatial analysis of pro-ethanol policies in the USA.
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Creator
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Boyle, Austin, Harriet L. Wilkes Honors College
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Abstract/Description
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The use of ethanol as a liquid fuel for automobiles began on a large scale in 1978. Since then, it has grown with the help of national subsidies for producers coupled with statewide incentives for producers and consumers. The market for ethanol more than doubled between 2001 and 2005, with even faster growth projected in the near future. Regulation has played more of a role on the recent rapid expansion of the market than natural market forces. This thesis surveys a brief history of ethanol...
Show moreThe use of ethanol as a liquid fuel for automobiles began on a large scale in 1978. Since then, it has grown with the help of national subsidies for producers coupled with statewide incentives for producers and consumers. The market for ethanol more than doubled between 2001 and 2005, with even faster growth projected in the near future. Regulation has played more of a role on the recent rapid expansion of the market than natural market forces. This thesis surveys a brief history of ethanol fuel usage and regulatory action in the United States and provides a few econometric models of production and consumption. Public policy creates a high level of demand for ethanol without consumer preferences changing much. This model could be used to assess the likely effects on the ethanol market of an MTBE ban in states that currently allow its use as an oxygenate.
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Date Issued
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2006
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PURL
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http://purl.flvc.org/FAU/11592
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Subject Headings
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Motor vehicles, Fuel consumption, Alcohol as a fuel, Gasoline, Additives, Environmental aspects, Agriculture and energy
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Format
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Document (PDF)