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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.
71

EXPERIMENTAL INVESTIGATION OF HIGH VELOCITY IMPACTS ON BRITTLE MATERIALS

Nathenson, David Isaac 07 February 2006 (has links)
No description available.
72

Kortsiktiga effekter avbikarbonatbehandling pålungmossa i plantskola / Short term effects on liverwort treated with sodiumbicarbonate

Stenström, Manne January 2022 (has links)
Årligen producerar svenska skogsplantskolor runt 400 miljoner plantor till skogsbruket.Lungmossan är ett av de stora ogräsen för de skogliga plantskolorna. Lungmossan breder utsig på plantbäddarna och omöjliggör hanteringen av plantorna. Idag finns det inget tillåtetbekämpningsmedel för att bekämpa lungmossa på marknaden. Behandling av bikarbonat i fastform har visat goda resultat men är svåra att genomföra i stor skala. I detta arbete harmöjligheten att bekämpa lungmossa med vattenlöslig bikarbonatbehandling studerats.Ett plantskoleförsök genomfördes i ett av Skogforsks växthus i Sävar. Försöket bestod av tvåförstudier och sedan ett huvudförsök med 9 olika försöksuppställningar. Totalt ingick 49Starpot 50 kassetter med 24–48 granplantor i varje. Resultatet visade att det går att behandlalungmossa med bikarbonat utblandat med vatten kortsiktigt, men att de skadorna som uppstårunder behandling på granplantorna gör metoden irrelevant. I stället bör vidare studier påbikarbonat i fast form undersökas.
73

High Temperature Corrosion of Single Crystal Sapphire and Zirconia in Coal Gasification and Commercial Glass Environments

Dicic, Zorana 16 July 2004 (has links)
To meet the requirements of precise temperature monitoring at high temperatures in extremely corrosive environments, such as in coal gasifiers, a new sensor technology has been developed. This optical, ultra high temperature measurement system utilizes single crystal sapphire as a sensing element. A series of experiments was performed to determine the corrosion resistance of single crystal sapphire and single crystal fully stabilized cubic zirconia at high temperatures in coal slag and soda lime glass. The amount of corrosion of sapphire and zirconia in corrosive slags was measured at 1200°C, 1300°C, and 1400°C for different exposure times. The microstructural features at the interface of sapphire and zirconia were investigated using SEM and EDX analysis. The experimental measurements as well as SEM micrographs show very little or no degradation of sapphire and zirconia samples in corrosive slags. An interesting phenomenon was observed in the EDX scans of sapphire in the coal slag: the iron from the slag appears to have completely separated from the silicon and deposited at the sapphire surface. This interesting observation can be further explored to study whether this iron layer can be used to control the corrosion of sapphire. / Master of Science
74

Isolamento e caracterização de ligninas de palha de cana-de-açúcar / Isolation and characterisation of lignins of sugarcane straw

Gambarato, Bruno Chaboli 19 September 2014 (has links)
Neste trabalho, foi realizada a caracterização de ligninas de palha de cana-de-açúcar. O isolamento das ligninas se deu por acidólise branda e por polpação soda, precedida ou não por pré-tratamento com ácido diluído ou por explosão a vapor. A palha de cana e as ligninas foram caracterizadas por Cromatografia Líquida de Alta Eficiência (CLAE), Espectrometrias no Infravermelho (FT-IR) e no Ultravioleta (UV), por Ressonância Magnética Nuclear de Prótons (1H RMN), Cromatografia de Permeação em Gel (GPC), Análise Termogravimétrica (TGA) e Calorimétrica (DSC), Análise Elementar e de Poder Calorífico Superior (PCS). A lignina técnica isolada por acidólise branda apresentou fórmula C9Har2,31Hal4,14O1,27(OH)ph0,58(OH)al1,19(OCH3)1,11 e relação H:G:S de 1 : 3,22 : 3,68, com 20% de condensação e massa molar média de 1908 Da. A cinética de termodegradação dessa lignina em atmosfera inerte se deu com energia de ativação de 13,90 kJ.mol-1, constante pré-exponencial 0,4799 min-1 e 42% em massa de carvão residual. Foram determinados, ainda, o coeficiente de extinção a 280 nm de 26,03 L.g-1 e o Poder Calorífico Superior de 23,72 kJ.g-1. A partir das informações obtidas em todas as análises, foi proposta uma estrutura para esta lignina. A deslignificação via polpação soda mostrou-se eficiente na remoção de lignina da matriz e foi verificado que, durante o processo, ocorre o rompimento de ligações entre a lignina e carboidratos, entretanto, algumas dessas ligações não são rompidas e o resíduo do processo, denominado lignina, contêm cerca de 17% carboidratos. A lignina soda apresentou poder calorífico superior de 25,14 kJ.g-1, 36% em massa de carvão residual e cinética de termodegradação com energia de ativação de 12,73 kJ.mol-1 e k0=0,4195 min-1. Foi verificado que as polpas soda que sofreram pré-tratamentos apresentaram um menor teor de lignina e maior solubilização de hemiceluloses. Estes tratamentos se mostraram eficientes na hidrólise dos complexos lignina-carboidrato e a ligninas obtidas apresentaram os menores teores de carboidrato residual e características estruturais diferentes das demais, mostrando-se mais condensadas em função das reações que ocorrem em meio ácido. Os coeficientes de extinção a 280 nm foram iguais a 24,2 L.g-1 e 23,3 L.g-1, respectivamente para as ligninas de explosão a vapor e pré-tratamento ácido e suas fórmulas estruturais determinadas por 1H RMN foram, respectivamente, C9Har1,59Hal4,12O0,84(OH)ph0,61(OH)al0,88(OCH3)1,51 e C9Har2,12Hal4,23O1,64(OH)ph0,83(OH)al0,58(OCH3)1,10. / In this work, the characterisation of lignins of sugarcane straw was made. The lignins were isolated by moderate acidolysis and soda process, preceded or not by either diluted acid or steam explosion pretreatments. The sugarcane straw and the lignins were characterised by High Performance Liquid Chromatography (HPLC), Infrared (FT-IR) and Ultraviolet (UV) Spectrometry, Proton Nuclear Magnetic Resonance (H1-RMN), Gel Permeation Chromatography (GPC), Thermogravimetrica analysis (TGA) and Differential Scattering Calormietry (DSC), Elemental Analysis and Heat Power (HP). The technical lignin isolated by moderate acidolysis has the formula C9Har2.31Hal4.14O1.27(OH)ph0.58(OH)al1.19(OCH3)1.11, H:G:S ratio of 1 : 3.22 : 3.68, is 20% condensed and its avarage molecular weight is 1908 Da. The thermal degradation kinetics analysis of this lignin in inert atmosphere was carried out, the results obtained were: activation energy of 13.80 kJ.mol-1, pre-exponential constant of 0.4799 min-1 and 42% residual char. The extinction coefficient obtained at 280 nm was 26.03 L.g-1 and the heat power 23.72 kJ.g-1. A structure was proposed for this lignin based on all the information obtained from these analyses. The delignification via soda process was efficient at removing lignin; during the process, the breaking of bonds between the lignin and carbohydrates was noticed, nevertheless, some of these bonds were not broken and the process residue, hereinafter called lignin, contains about 17% carbohydrates. The soda lignin has heat power of 25.14 kJ.g-1, 36% residual char and the thermal degradation kinetics ocurred with activation energy of 12.73 kJ.mol-1 and k0=0.4195 min-1. It was found that pretreated soda pulps have a lower lignin content and higher solubilisation of complexes, the lignins obtained had the lowest residual carbohydrates contents and different structural features from the untreated ones, being more condensed due to the reactions that occur in acid medium. The extinction coefficients at 280 nm obtained are 24.2 L.g-1 and 23.3 L.g-1, the structural formulas determined by 1H RMN are C9Har1.59Hal4.12O0.84(OH)ph0.61(OH)al0.88(OCH3)1.51 and C9Har2.12Hal4.23O1.64(OH)ph0.83(OH)al0.58(OCH3)1.10 for the steam explosion and acid pretreatment lignins, respectively.
75

CARACTERIZAÇÃO MECÂNICA E TRANSIÇÃO FRÁGIL-DÚCTIL EM MATERIAIS VITROCERÂMICOS

Mathias, Ivan 01 April 2015 (has links)
Made available in DSpace on 2017-07-21T19:25:45Z (GMT). No. of bitstreams: 1 Ivan Mathias.pdf: 11996423 bytes, checksum: f3bdcfad9b494e72052f6a36c4a749d4 (MD5) Previous issue date: 2015-04-01 / Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Paraná / In this work two vitreous systems are studied, the lithium disilicate (LS2) and sodiumcalcium-silica with stoichiometry 2Na2O.CaO.3SiO2 (2N1C3S) and the glassceramics formed from these by heat treatment. Several properties were determined for the two systems as a function of crystallized volume fraction, from glass to fully crystallization (100%), highlighting the fracture toughness and the brittle-ductile transition, with the last two determined only for the LS2 glass-ceramic. Hardness and elastic modulus were obtained for the two glass-ceramics and their values increase with the crystallized volume fraction in the glass ceramic, with the exception of hardness of 2N1C3S, which has its maximum for the crystallized volume fraction of 9%. Thermal expansion coefficients were determined and are larger in the LS2 glassy phase and in the 2N1C3S crystalline phase, thereby generating mean residual stresses obtained by Selsing model of -76 MPa for the LS2 (compression in the crystal) and 232 MPa for the 2N1C3S (traction in the crystal). The indentation fracture toughness was also determined for the two systems using the Anstis' and Niihara's models. The results show an increase of indentation fracture toughness with the crystalline volume fraction for LS2 glass-ceramic and also a dependence with indentation load. As for the 2N1C3S glass-ceramic, indentation fracture toughness are reduced at intermediate crystalline fractions, which is attributed to residual stresses arising from the difference between the thermal expansion mismatch between the glass and the crystalline phases. LS2 glass-ceramic flexural strength increases with the crystalline fraction, from 103 ± 3 MPa for the glass to 260 ± 20 MPa for the fully crystallized sample. Without the removal of the crystallization surface layer, this value rises to 290 ± 20 MPa. The increase in flexural strength in the first 20% of the crystallized fraction is more pronounced. As the size of the precipitates was kept constant, this increase can be related only to the increase in the crystallized fraction. The residual stress in the matrix, the critical radius of spontaneous cracking of the crystals and the crack mean free path between the precipitates were considered in the analysis of the increase in flexural strength. The existence of pores in the samples was a factor that limited its resistance. The fracture toughness (KDTIC) a function of the crystallized fraction was determined for LS2 glassceramics using the double torsion technique. It was found that KDTIC increases with the crystallized fraction, from 0.75 MPa.m1/2 for the glass to about 3.50 ± 0.05 MPa.m1/2 for the fully crystallized sample, a significant increase of approximately five times. Several factors were analyzed as possible causes of the increase in KDTIC. The experimental data are better adjusted with a recently proposed model with one adjustable parameter that relates the ratio of the crystal and glass areas to the crystallized volume fraction. The brittle-ductile transition (BDT) of LS2 glass and glass-ceramic samples (39% crystallized volume fraction) were determined for three different strain rates. BDT temperatures were determined for each strain rate.Activation energies of BDT for the glass and glass-ceramic were obtained, which were 5.2 ± 0.2 eV and 7 ± 2 eV. It was found that BDT activation energy in glass resembles the activation energy of the LS2 viscous flow, thus concluding the BDT in LS2 is governed by viscous flow of the glass matrix. Finally, the fact of the activation energy of the glass ceramic be larger than the glass was attributed to the fact that the viscosity of the vitreous matrix is "hindered" by the presence of crystalline precipitates. A viscosity model of a rigid spheres composite was used as an analogy to explain this observation. / No presente trabalho são estudados dois sistemas vítreos, o dissilicato de lítio (LS2) e o soda-cal-sílica de estequiometria 2Na2O.CaO.3SiO2 (2N1C3S), bem como os vitrocerâmicos formados a partir destes através de tratamentos térmicos. Diversas propriedades foram determinadas para os dois sistemas em função da fração cristalizada, desde vidro até os 100%, com destaque para a tenacidade à fratura e a transição frágil-dúctil, sendo estas últimas determinadas somente para o LS2. Dureza e módulo de elasticidade foram obtidos para os dois sistemas e seus valores aumentam com a fração volumétrica cristalizada no vitrocerâmico, com exceção da dureza no 2N1C3S, que tem seu máximo para a fração cristalizada de 9%. Os coeficientes de expansão térmica foram determinados e são maiores na fase vítrea do LS2 e na fase cristalina do 2N1C3S, gerando assim tensões residuais médias obtidas pelo modelo de Selsing de -76 MPa para o LS2 (compressiva no cristal) e 232 MPa para o 2N1C3S (trativa no cristal). A tenacidade à fratura por indentação (KC) foi determinada também para os dois sistemas, sendo utilizados os modelos de Anstis e Niihara. Os resultados mostram um aumento com a fração cristalina para o LS2 e também uma dependência com a carga utilizada no teste. Já para o 2N1C3S, os valores de KC sofrem uma redução em frações cristalinas intermediárias, comportamento atribuído às tensões residuais oriundas da diferença entre os coeficientes de expansão térmica e anisotropias elásticas do material. Os ensaios de resistência à flexão mostraram que para o LS2 a resistência aumenta com a fração cristalina, passando de 103 ± 3 MPa para o vidro para 260 ± 20 MPa para a amostra totalmente cristalizada. Se não removermos a camada de cristalização superficial, este valor sobe para 290 ± 20 MPa. O aumento da resistência à flexão nos primeiros 20% da fração cristalizada é mais pronunciado. Como o tamanho dos precipitados foi mantido constante, esse aumento pode ser relacionado apenas ao aumento na fração cristalizada. A tensão residual na matriz, o raio crítico dos cristais para trincamento espontâneo e o livre caminho médio da trinca entre os precipitados foram considerados na análise do aumento da resistência à flexão. A existência de poros nas amostras foi um fator que limitou a sua resistência. Caso amostras sem poros fossem feitas, um aumento em torno de 20 a 30% da resistência seria obtido. A tenacidade à fratura (KDTIC) foi determinada para o LS2 pela técnica de torção dupla em função da fração cristalizada. Foi verificado que KDTIC aumenta com a fração cristalizada, passando de 0,75 MPa.m1/2 para o vidro para cerca de 3,50 ±0,05 MPa.m1/2 para a amostra totalmente cristalizada, um aumento significativo de aproximadamente cinco vezes. Diversos fatores foram apontados como possíveis causas do aumento da tenacidade e foi verificado que os fatores considerados de forma isolada não são suficientes para descrever completamente o aumento na tenacidade. Os dados experimentais são melhor ajustados com um modelo de um parâmetro de ajuste recentemente proposto que relaciona a razão entre as áreas dos cristais e do vidro na superfície de fratura com a fração cristalizada. A transição frágil-dúctil (TFD) de amostras vítreas e vitrocerâmica (39% fração cristalizada) de LS2 foram determinadas para três taxas de deformação. Foram determinadas as temperaturas de TFD para cada uma das taxas e foi verificada uma dependência com a taxa de deformação. Foram calculadas as energias de ativação para a TFD no vidro e vitrocerâmico, sendo elas de 5,2 ± 0,2 eV e 7 ± 2 eV. Verificou-se que a energia de ativação da TFD no vidro se assemelha a energia de ativação do escoamento viscoso do LS2, concluindo assim que a TFD no LS2 é governada pelo escoamento viscoso da matriz vítrea. Por fim, o fato da energia de ativação do vitrocerâmico ser maior que do vidro foi atribuída ao fato de que a viscosidade da matriz vítrea seria "dificultada" pela presença dos precipitados cristalinos. Um modelo de viscosidade de um compósito com esferas rígidas foi utilizado como analogia para explicar essa observação.
76

Isolamento e caracterização de ligninas de palha de cana-de-açúcar / Isolation and characterisation of lignins of sugarcane straw

Bruno Chaboli Gambarato 19 September 2014 (has links)
Neste trabalho, foi realizada a caracterização de ligninas de palha de cana-de-açúcar. O isolamento das ligninas se deu por acidólise branda e por polpação soda, precedida ou não por pré-tratamento com ácido diluído ou por explosão a vapor. A palha de cana e as ligninas foram caracterizadas por Cromatografia Líquida de Alta Eficiência (CLAE), Espectrometrias no Infravermelho (FT-IR) e no Ultravioleta (UV), por Ressonância Magnética Nuclear de Prótons (1H RMN), Cromatografia de Permeação em Gel (GPC), Análise Termogravimétrica (TGA) e Calorimétrica (DSC), Análise Elementar e de Poder Calorífico Superior (PCS). A lignina técnica isolada por acidólise branda apresentou fórmula C9Har2,31Hal4,14O1,27(OH)ph0,58(OH)al1,19(OCH3)1,11 e relação H:G:S de 1 : 3,22 : 3,68, com 20% de condensação e massa molar média de 1908 Da. A cinética de termodegradação dessa lignina em atmosfera inerte se deu com energia de ativação de 13,90 kJ.mol-1, constante pré-exponencial 0,4799 min-1 e 42% em massa de carvão residual. Foram determinados, ainda, o coeficiente de extinção a 280 nm de 26,03 L.g-1 e o Poder Calorífico Superior de 23,72 kJ.g-1. A partir das informações obtidas em todas as análises, foi proposta uma estrutura para esta lignina. A deslignificação via polpação soda mostrou-se eficiente na remoção de lignina da matriz e foi verificado que, durante o processo, ocorre o rompimento de ligações entre a lignina e carboidratos, entretanto, algumas dessas ligações não são rompidas e o resíduo do processo, denominado lignina, contêm cerca de 17% carboidratos. A lignina soda apresentou poder calorífico superior de 25,14 kJ.g-1, 36% em massa de carvão residual e cinética de termodegradação com energia de ativação de 12,73 kJ.mol-1 e k0=0,4195 min-1. Foi verificado que as polpas soda que sofreram pré-tratamentos apresentaram um menor teor de lignina e maior solubilização de hemiceluloses. Estes tratamentos se mostraram eficientes na hidrólise dos complexos lignina-carboidrato e a ligninas obtidas apresentaram os menores teores de carboidrato residual e características estruturais diferentes das demais, mostrando-se mais condensadas em função das reações que ocorrem em meio ácido. Os coeficientes de extinção a 280 nm foram iguais a 24,2 L.g-1 e 23,3 L.g-1, respectivamente para as ligninas de explosão a vapor e pré-tratamento ácido e suas fórmulas estruturais determinadas por 1H RMN foram, respectivamente, C9Har1,59Hal4,12O0,84(OH)ph0,61(OH)al0,88(OCH3)1,51 e C9Har2,12Hal4,23O1,64(OH)ph0,83(OH)al0,58(OCH3)1,10. / In this work, the characterisation of lignins of sugarcane straw was made. The lignins were isolated by moderate acidolysis and soda process, preceded or not by either diluted acid or steam explosion pretreatments. The sugarcane straw and the lignins were characterised by High Performance Liquid Chromatography (HPLC), Infrared (FT-IR) and Ultraviolet (UV) Spectrometry, Proton Nuclear Magnetic Resonance (H1-RMN), Gel Permeation Chromatography (GPC), Thermogravimetrica analysis (TGA) and Differential Scattering Calormietry (DSC), Elemental Analysis and Heat Power (HP). The technical lignin isolated by moderate acidolysis has the formula C9Har2.31Hal4.14O1.27(OH)ph0.58(OH)al1.19(OCH3)1.11, H:G:S ratio of 1 : 3.22 : 3.68, is 20% condensed and its avarage molecular weight is 1908 Da. The thermal degradation kinetics analysis of this lignin in inert atmosphere was carried out, the results obtained were: activation energy of 13.80 kJ.mol-1, pre-exponential constant of 0.4799 min-1 and 42% residual char. The extinction coefficient obtained at 280 nm was 26.03 L.g-1 and the heat power 23.72 kJ.g-1. A structure was proposed for this lignin based on all the information obtained from these analyses. The delignification via soda process was efficient at removing lignin; during the process, the breaking of bonds between the lignin and carbohydrates was noticed, nevertheless, some of these bonds were not broken and the process residue, hereinafter called lignin, contains about 17% carbohydrates. The soda lignin has heat power of 25.14 kJ.g-1, 36% residual char and the thermal degradation kinetics ocurred with activation energy of 12.73 kJ.mol-1 and k0=0.4195 min-1. It was found that pretreated soda pulps have a lower lignin content and higher solubilisation of complexes, the lignins obtained had the lowest residual carbohydrates contents and different structural features from the untreated ones, being more condensed due to the reactions that occur in acid medium. The extinction coefficients at 280 nm obtained are 24.2 L.g-1 and 23.3 L.g-1, the structural formulas determined by 1H RMN are C9Har1.59Hal4.12O0.84(OH)ph0.61(OH)al0.88(OCH3)1.51 and C9Har2.12Hal4.23O1.64(OH)ph0.83(OH)al0.58(OCH3)1.10 for the steam explosion and acid pretreatment lignins, respectively.
77

THE ROLE OF SNAP AND HABIT FORMATION ON HOUSEHOLD CONSUMPTION BEHAVIOR

Burney, Shaheer 01 January 2017 (has links)
This collection of essays examines the impact of two antecedents of household food consumption: SNAP and habit formation to nutrients. Household food choice invariably plays a substantial role in health outcomes such as obesity. Low-income households may be especially vulnerable to obesity as they face a more restricted set of food choices due to income constraints and may have less information on healthy eating relative to high-income households. This dissertation unravels this dynamic by providing causal estimates of the effect of two major determinants of food choice. Chapter 2 and chapter 3 test the impact of SNAP participation on consumption of foods that are likely to cause obesity. With some exceptions, SNAP restricts benefits to be spent only on unprepared grocery food items from participating retailers. Chapter 2 considers the broad category of Food Away From Home (FAFH) which is shown to be less healthy than meals prepared at home and shows that SNAP significantly reduces FAFH expenditure of participants. However, the magnitude of this decrease is not large enough to have a tangible impact on obesity. Chapter 3 considers household expenditure on carbonated soda, which is the key source of sugar intake among low-income households. Not only is carbonated soda SNAP-eligible, it is cheaper when purchased with SNAP benefits relative to cash because benefits are exempt from all sales taxes. Results show that SNAP participation leads to a significant rise in carbonated soda sales in low-income counties. I also find that the SNAP tax exemption does not lead to higher consumption among participants relative to non-participants. Chapter 4 tests habit formation to dietary fat using purchases of ground meat and milk products. Products in both categories have salient fat content information on the packaging. Products within each category differ only by fat content and are usually identical otherwise. Differences in habit formation are, therefore, caused by different levels of fat content. Results show a positive association between habit formation and fat content for all products in the ground meat category and all products, except fat-free milk, in the milk category. However, this relationship is modest leading to the conclusion that policy interventions, such as a saturated fat tax, might be effective in discouraging consumption of high fat products.
78

Relaxation and nanomechanical studies of the vickers residual stress field in glass

Kese, Kwadwo O. January 2004 (has links)
The Vickers residual stress field (VRSF) in soda-lime glass results from the elastic-plastic contact event that takes place when a Vickers diamond pyramid is loaded onto the surface of the material in an indentation cycle. The importance of elastic-plastic indentation lies in the contact damage that it gives rise to in the surface of the glass. Since such surface flaws can be characterised, with respect to shape and size, they offer the opportunity to study naturally occurring flaws in glass and brittle materials in general. The residual stress field is not passive; rather it exerts a crack opening force on the associated crack system during subsequent strength testing of a Vickers-indented sample through a residual stress field coefficient, c. Besides the strength-controlling properties, the elastic-plastic contact residual stress field is also important as a region where the influence of mechanical excitation on material properties such as hardness, H, and elastic modulus, E, can be studied. This thesis concerns studies that were made to characterise the Vickers residual stress field by first measuring the magnitude and distribution of stresses around it, using nanoindentation with a cube corner tip. With a Berkovich tip in nanoindentation, experiments were conducted in the VRSF to study the dependence of hardness, H and elastic modulus, E, on stresses in soda-lime glass: a strong E dependence on stress was observed, while H was not affected unless the stresses were high. In the process, a method was developed to determine the true contact area during elastic-plastic nanoindentation when the Oliver-Pharr method is used for the data analysis. The observed elastic modulus dependence on stress was then utilised in a study where it was shown that the VRSF responds differently to relaxation annealing on either side of the glass transition temperature. This result was then used to explain strength recovery trends in annealed Vickers-indented glass specimens.
79

Utilization Of Soda And Beer Wastes In Cementitious Systems

Aleessa Alam, Burhan 01 September 2009 (has links) (PDF)
To maintain the sustainability of cement and concrete production, there is a trend to use wastes in their production. Soda waste, generated by soda ash production process, and beer waste, generated by beer filtration process, are two locally produced wastes in Turkey and many other countries. The nature of these wastes, mostly their fineness, makes them possible to be used in concrete production, especially as a viscosity modifying agent in the self consolidating type of concrete. In this study, the addition of soda and beer wastes to self consolidating mortar (SCM) and self consolidating concrete (SCC), without any treatment but drying, and its effect on their properties were investigated. Mortar and concrete mixes were prepared using these two wastes as cement or aggregate replacement in various amounts. Tests like slump flow, V-Funnel and L-Box for determining the fresh properties, and compressive strength for the hardened properties of the mixtures were carried out to examine the effects of these wastes on the properties of SCM and SCC. The tests revealed that soda waste takes no role in the strength development of the mixes. However, it is possible to use this waste as aggregate replacement to improve the workability and flowability properties of SCM and SCC. The use of beer waste showed contradictive results. A special treatment for this waste before using it in concrete might be required.
80

Synthesis Of Alinite Cement Using Soda Solid Waste

Gunes, Asli 01 September 2010 (has links) (PDF)
This study is dedicated to give a production route for a kind of low energy cement called alinite cement using the waste material of soda industry as the main raw material. Soda solid waste, clay and minor amount of iron ore were mixed with certain quantities and burned at six different burning temperatures of 1050, 1100, 1150, 1200, 1350, and 1450 &ordm / C. The resultant clinkers were investigated by mineralogical and chemical analysis. Mineralogical analyses were performed by X-Ray Diffraction (XRD) technique. XRD analyses revealed the formation of alinite phase in the clinkers. Chemical analyses were performed by X-Ray Fluorescence spectroscopy technique and by wet chemical analysis. Especially, free lime content of the clinkers was searched and an optimum burning temperature was determined. In order to find the compressive strength of the alinite cement, larger amounts of alinite clinker were manufactured in wet rod shape raw mix in a laboratory type of furnace at 1200, 1350 and 1450 &ordm / C. The results have shown that forming alinite phase requires ~6wt % chlorine. Alinite clinker is obtained using soda waste at the temperature range between 1050 and 1200 &ordm / C. However, the free CaO becomes much lower as 0.12 at 1200 &ordm / C. Moreover, a lime saturation factor of 76, which is lower than ordinary Portland clinker is obtained. Satisfactory compressive strength was achieved by gypsum addition.

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