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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.
1

Efeito do teor e granulometria de borracha, do tempo e da temperatura de mistura e do tempo de armazenamento sobre propriedades do ligante asfalto-borracha / Effect of particle size and content of rubber, the mixing time and temperature and the storage time on the rubber asphalt binder properties

Ferro, Claudia Cristina 23 January 2004 (has links)
A produção de um ligante modificado com a borracha de pneus usados tem-se tornado viável em virtude do aumento da rigidez a temperaturas elevadas e da flexibilidade a baixas temperaturas que ele proporciona no revestimento dos pavimentos flexíveis, contribuindo para amenizar dois dos principais defeitos que afetam este tipo de pavimento, a saber, a deformação permanente nas trilhas de roda e as trincas por fadiga. Em acréscimo, consegue-se diminuir a quantidade de pneus dispostos em aterros sanitários, disponibilizando espaço e evitando problemas ambientais e de saúde pública, pois o acúmulo de pneus facilita a procriação de insetos e de outros vetores de doenças. Utilizando-se ensaios tradicionais e ensaios do método Superpave, neste trabalho são analisados os efeitos dos principais fatores que condicionam o comportamento do ligante asfalto-borracha (teor granulometria das partículas de borracha, tempo e temperatura de mistura, mantida constante em 155ºC) e as alterações nas propriedades físicas do ligante asfalto-borracha durante o tempo de armazenamento. / The production of a modified binder with used tire has become possible because of the increase in the stiffness at high temperature and the flexibility at low temperature that it brings to the surface layers of flexible pavements. The asphalt-rubber binders help to prevent two of the most important problems that affect flexible pavements, that is, the permanent deformation in the wheel tracks and fatigue cracking. In addition, it is possible to reduce the amount of tires disposed in sanitary landfills, increasing the service-life and avoiding environmental and health problems. Using traditional tests and tests of the Superpave method, this study analyses the effects of the main factors that affects the behavior of the asphalt-rubber binder (content and gradation of rubber particles, reaction temperature fixed in 155ºC and time) and the changes in the physical properties of asphalt-rubber binder during the storage time.
2

Efeito do teor e granulometria de borracha, do tempo e da temperatura de mistura e do tempo de armazenamento sobre propriedades do ligante asfalto-borracha / Effect of particle size and content of rubber, the mixing time and temperature and the storage time on the rubber asphalt binder properties

Claudia Cristina Ferro 23 January 2004 (has links)
A produção de um ligante modificado com a borracha de pneus usados tem-se tornado viável em virtude do aumento da rigidez a temperaturas elevadas e da flexibilidade a baixas temperaturas que ele proporciona no revestimento dos pavimentos flexíveis, contribuindo para amenizar dois dos principais defeitos que afetam este tipo de pavimento, a saber, a deformação permanente nas trilhas de roda e as trincas por fadiga. Em acréscimo, consegue-se diminuir a quantidade de pneus dispostos em aterros sanitários, disponibilizando espaço e evitando problemas ambientais e de saúde pública, pois o acúmulo de pneus facilita a procriação de insetos e de outros vetores de doenças. Utilizando-se ensaios tradicionais e ensaios do método Superpave, neste trabalho são analisados os efeitos dos principais fatores que condicionam o comportamento do ligante asfalto-borracha (teor granulometria das partículas de borracha, tempo e temperatura de mistura, mantida constante em 155ºC) e as alterações nas propriedades físicas do ligante asfalto-borracha durante o tempo de armazenamento. / The production of a modified binder with used tire has become possible because of the increase in the stiffness at high temperature and the flexibility at low temperature that it brings to the surface layers of flexible pavements. The asphalt-rubber binders help to prevent two of the most important problems that affect flexible pavements, that is, the permanent deformation in the wheel tracks and fatigue cracking. In addition, it is possible to reduce the amount of tires disposed in sanitary landfills, increasing the service-life and avoiding environmental and health problems. Using traditional tests and tests of the Superpave method, this study analyses the effects of the main factors that affects the behavior of the asphalt-rubber binder (content and gradation of rubber particles, reaction temperature fixed in 155ºC and time) and the changes in the physical properties of asphalt-rubber binder during the storage time.
3

Crystallisation aspects of the wet-process phosphoric acid industry

Arlow, Antoinette 15 April 2004 (has links)
Fedmis Pty (Ltd) situated in Palaborwa, South Africa produces phosphoric acid using the wet process production process. For this study, two main areas of concern in the wet process phosphoric acid production were investigated. The first area is the formation of sludge in the system due to impurities that reduces the grade of the acid produced, thereby lowering the selling price. The second area is the crystallisation of the gypsum that influences filtration and thereby affects plant productivity. These two aspects were investigated separately as they occur in different steps of the production process at different acid concentrations. A major component of the acid sludge is known as x-compound, ((Fe,Al)3KH)14 (PO4)8.4H2O). The purpose of the investigation of x-compound is to determine what effects different ionic impurities have on its precipitation and to determine if these effects could be used to decrease the amount of sludge formation. Due to the complexity of the system and the wide variety of impurities only the major impurities were considered in this study. These impurities included potassium (K+), sodium (Na+), magnesium (Mg2+), aluminium (Al3+) and iron (Fe3+). For all the experiments investigating the effect of impurities, analytical reagents were used on laboratory scale. For the silica experiments, commercially available samples were used. For the experiments investigating the impurity effects on the precipitation of x-compound it was found that: <ul> <li> Agitation increases x-compound precipitation and can be used commercially to increase the precipitation rate to a point where sludge can be removed before transportation.</li> <li> Adding x-compound seeding crystals or magnesium ions also increases precipitation.</li> <li> Adding gypsum, sodium, hexafluorosilicates or fluorosilic acid reduces the precipitation, with sodium ions producing the lowest yield. This reduction is however not sufficient to be used commercially.</li> </ul> From the Raman study it became clear why x-compound precipitation is such a slow process. E At low acid concentrations, more H2PO4 - ions are present that form a complex with iron and aluminium. E As the acid concentration increases the concentration of H2PO4- ions decrease as the degree of dissociation of phosphoric acid decreases. The ferric- H2PO4- and aluminium- H2PO4- complexes become less stable and ultimately precipitation of the x-compound is favoured above solvation. E Addition of potassium impurities to the solutions had no visible effect on the Raman spectra and is suspected not to form a complex with the acid. From the silica sources investigated namely Dicalite, Serina Kaolin, Foskor silica and Aerosil 200 it can be concluded that none of the sources will be useful for the removal of potassium through formation of potassium hexafluorosilicates. For the determination of the concentration of impurities present in the production of phosphoric acid, the Fedmis monitoring program was initiated. It included the monitoring of Foskor rock analyses on a daily basis, and the monitoring of the 27%, 39% and 54% P2O5 phosphoric acid and precipitate, from these acid solutions on a weekly basis. From the investigation of the effect of these impurities on the solubility of potassium hexafluorosilicates, it was found that magnesium causes K2SiF6 to be the most soluble and fluoride the least. Unfortunately, the impurities did not help to reduce the potassium concentrations in the acid to below the required amount for sludge formation. For the calcium sulphate dihydrate surfactant experiments, the purpose of the investigation was to determine whether higher crystallisation qualities could be obtained to improve plant productivity. The investigation was limited to using surfactants with sulphate or phosphate functionalities and experiments were done on laboratory scale using analytical reagents. Atphos E3205, Atpol E3202 and Atpol E1231 are polyethoxylated alkyl phenol phosphate esters that had no visible effect on the crystal structure of the precipitated gypsum, but differences in the crystal sizes were observed. Smaller crystal structures with relatively equal masses compared to reference experiments are an indication of a growth inhibitor and a nucleation promoter as seen with Atphos E3205 and Atpol E3202. Increased crystal sizes were obtained using Atpol E1231. The use of Calsoline Oil caused a wider crystal size distribution in the precipitated crystals as thin and broad crystals with approximately the same length are found. The crystal mass obtained is also approximately the same as that of the reference experiment. Thus, it can be concluded that the surfactant affects the growth of the crystals and not the nucleation. Arlatone 1489, calcium gluconate monohydrate, Dowfax Hydrotrope and Tamol NN 8906 had no visible effect on the structure or size of the precipitated gypsum crystals. With the use of Nansa SS30, drastic effects were seen on the crystallisation of the calcium sulphate as small hexagonal rods were found. With an increase in surfactant concentration, there is a clear decrease in the mass of crystals obtained as well as crystal size. An increase in the crystal size distribution and a decrease in crystal size reduced the filtration rate dramatically. Experiments carried out for 24 hours exhibited the same trends where there is a decrease in yield with an increase in surfactant concentration. Higher yields were however obtained proving that mass transfer barriers were overcome. The results from these experiments again indicate that the surfactant affects crystal growth and nucleation. With the use of Dowfax 3B2 there is definite reduction in yield with an increase in surfactant concentration reaching a minimum at approximately 70% yield. Due to the presence of large amounts of smaller crystals and the almost constant yield obtained compared to the reference experiment, it can be concluded that this surfactant is a growth and not a nucleation inhibitor. As with Nansa SS30, experiments where Empicol LZ/D was used show a continuous decrease in the yield obtained with an increase in the surfactant concentration. At higher concentration of Empicol LZ/D, it seems as if this surfactant changed from a growth promoter to a growth inhibitor because although broad longer crystals are present, there are now also much smaller crystals formed. The crystal size distribution also broadens considerably. Overall, very high yields were obtained using Empimin KSN70 and the observed crystal size distributions were very narrow. The only difference was that the crystals appeared to be more porous or fibrous compared to the reference experiment. It is recommended that the experiments showing promise as crystal habit modifiers like Nansa SS30 and Empicol LZ/D be investigated in more detail as well as combinations of surfactants. Both the areas of concern in the process were investigated successfully. For the sludge formation problem, it is now clear what effects the precipitation of x-compound as well as what affect the impurities and operating conditions have. For the crystallisation of gypsum using surfactants, it was proven that surfactants could be used to affect crystal growth, shape and distribution and in this way influence filtration. / Dissertation (MSc(Chemical Engineering))--University of Pretoria, 2005. / Chemical Engineering / unrestricted
4

Análise da viabilidade técnica da utilização do ligante asfalto-borracha em obras de pavimentação / not available

Oda, Sandra 08 December 2000 (has links)
Este trabalho apresenta estudo sobre a viabilidade técnica da incorporação de borracha de pneus em ligantes asfálticos utilizados em obras de pavimentação. Trata-se de uma alternativa para solucionar um grave problema ambiental, pois no Brasil, anualmente, são descartados mais de 30 milhões de pneus, dos quais a maior parte é disposta em locais inadequados, servindo para a procriação de vetores de doenças e representando risco de contaminação do meio-ambiente. Os efeitos dos principais fatores que condicionam o comportamento do ligante asfalto-borracha (teor e granulometria da borracha, temperatura de mistura, tempo de reação) são avaliados através de ensaios tradicionais de caracterização de ligantes asfálticos e também ensaios do Método Superpave, que determinam propriedades fundamentais, diretamente relacionadas ao desempenho dos pavimentos no campo. Os resultados da análise estatística da programação fatorial de ensaios laboratoriais desenvolvida evidenciam o efeito preponderante do teor de borracha e, principalmente, que o ligante asfalto-borracha pode aumentar a resistência ao acúmulo de deformação permanente e ao aparecimento de trincas por fadiga do revestimento. / This work presents the results of a study about the technical feasibility of the use of asphalt-rubber binder by the asphalt paving industry. In Brazil, more than 30 million tires a year are disposed, mostly in inadequate sites, causing serious health and environmental problems. The effects of the main factors (rubber content, rubber particle size, temperature of mixture, reaction time) on the behavior of asphalt-rubber binders are evaluated by traditional tests and also by tests of the Superpave Method, which are based on fundamental properties, directly related to field performance. The results of the statistical analysis of the factorial design of laboratory experiments show the most significant effect of rubber content and, mainly, that asphalt-rubber binder can increase the resistance to permanent deformation and fatigue cracking.
5

Análise da viabilidade técnica da utilização do ligante asfalto-borracha em obras de pavimentação / not available

Sandra Oda 08 December 2000 (has links)
Este trabalho apresenta estudo sobre a viabilidade técnica da incorporação de borracha de pneus em ligantes asfálticos utilizados em obras de pavimentação. Trata-se de uma alternativa para solucionar um grave problema ambiental, pois no Brasil, anualmente, são descartados mais de 30 milhões de pneus, dos quais a maior parte é disposta em locais inadequados, servindo para a procriação de vetores de doenças e representando risco de contaminação do meio-ambiente. Os efeitos dos principais fatores que condicionam o comportamento do ligante asfalto-borracha (teor e granulometria da borracha, temperatura de mistura, tempo de reação) são avaliados através de ensaios tradicionais de caracterização de ligantes asfálticos e também ensaios do Método Superpave, que determinam propriedades fundamentais, diretamente relacionadas ao desempenho dos pavimentos no campo. Os resultados da análise estatística da programação fatorial de ensaios laboratoriais desenvolvida evidenciam o efeito preponderante do teor de borracha e, principalmente, que o ligante asfalto-borracha pode aumentar a resistência ao acúmulo de deformação permanente e ao aparecimento de trincas por fadiga do revestimento. / This work presents the results of a study about the technical feasibility of the use of asphalt-rubber binder by the asphalt paving industry. In Brazil, more than 30 million tires a year are disposed, mostly in inadequate sites, causing serious health and environmental problems. The effects of the main factors (rubber content, rubber particle size, temperature of mixture, reaction time) on the behavior of asphalt-rubber binders are evaluated by traditional tests and also by tests of the Superpave Method, which are based on fundamental properties, directly related to field performance. The results of the statistical analysis of the factorial design of laboratory experiments show the most significant effect of rubber content and, mainly, that asphalt-rubber binder can increase the resistance to permanent deformation and fatigue cracking.
6

Estudo em laboratório do desempenho de concreto asfáltico usinado a quente empregando ligante tipo asfalto-borracha / not available

Faxina, Adalberto Leandro 18 July 2002 (has links)
Pesquisas sobre aplicação de borracha de pneus descartados em pavimentação asfáltica vêm sendo desenvolvidas desde a década de 1960, especialmente nos Estados Unidos e, desde o início da década de 1990, no Brasil, como alternativa para diminuição dos problemas ambientais gerados por estes resíduos sólidos. Esta pesquisa tem por objetivo avaliar o desempenho de três misturas asfálticas do tipo concreto asfáltico usinado à quente: duas empregando teores diferentes de borracha moída e óleo de xisto (CAP 40 + 12% de borracha + 10% de óleo de xisto e CAP 40 + 20% de borracha + 15% de óleo de xisto) e uma convencional. Este estudo faz parte de um programa de pesquisa coordenado pela Escola de Engenharia de São Carlos da Universidade de São Paulo (EESC-USP), Universidade Estadual de Maringá (UEM) e Petrobrás, envolvendo a execução de misturas com borracha e óleo de xisto em trechos experimentais. Foram realizadas dosagens Marshall e ensaios de resistência à tração, módulo de resiliência e fluência por compressão uniaxial estática. Os corpos-de-prova empregados nos ensaios foram moldados no teor ótimo de cimento asfáltico referente a cada uma das misturas. Constatou-se a viabilidade técnica da adição de óleo extensor para a incorporação de borracha de pneus descartados em concreto asfáltico, permitindo a obtenção de resultados satisfatórios quanto aos projetos de dosagem das misturas pelo método Marshall. Com base nos resultados dos ensaios realizados, acredita-se ser viável a execução de trechos experimentais empregando as duas misturas modificadas. / Researches on the application of discarded tires in asphaltic pavements has been developed since 1960, mainly in the United States and since the beginning of the 90\'s in Brazil, as an alternative to the reduction of environmental problems created by this kind of solid residues. The purpose of this research is to evaluate the performance of three hot mix asphalt concrete: two using different crumb rubber and shale oil contents (CAP 40 + 12% rubber + 10% shale oil and CAP 40 + 20% rubber + 15% shale oil) and a conventional hot mix asphalt concrete. The research is part of a major program coordinated by the Universidade de São Paulo (EESC-USP), Universidade Estadual de Maringá and Petrobras, comprehending the execution of asphaltic mixtures using tire rubber and shale oil in experimental road segments. The tests performed are: Marshall test, indirect tension, resilient modulus and static creep. The samples tested were compacted in the optimum binder content of each mixture. Good results obtained in tests confirrned the technical viability of using the shale oil as extender in crumb rubber asphalt hot mixtures. The results lead to the conclusion that experimental road sections or segments may be constructed with both tested rubber-oil modified asphalt mixtures.
7

Estudo em laboratório do desempenho de concreto asfáltico usinado a quente empregando ligante tipo asfalto-borracha / not available

Adalberto Leandro Faxina 18 July 2002 (has links)
Pesquisas sobre aplicação de borracha de pneus descartados em pavimentação asfáltica vêm sendo desenvolvidas desde a década de 1960, especialmente nos Estados Unidos e, desde o início da década de 1990, no Brasil, como alternativa para diminuição dos problemas ambientais gerados por estes resíduos sólidos. Esta pesquisa tem por objetivo avaliar o desempenho de três misturas asfálticas do tipo concreto asfáltico usinado à quente: duas empregando teores diferentes de borracha moída e óleo de xisto (CAP 40 + 12% de borracha + 10% de óleo de xisto e CAP 40 + 20% de borracha + 15% de óleo de xisto) e uma convencional. Este estudo faz parte de um programa de pesquisa coordenado pela Escola de Engenharia de São Carlos da Universidade de São Paulo (EESC-USP), Universidade Estadual de Maringá (UEM) e Petrobrás, envolvendo a execução de misturas com borracha e óleo de xisto em trechos experimentais. Foram realizadas dosagens Marshall e ensaios de resistência à tração, módulo de resiliência e fluência por compressão uniaxial estática. Os corpos-de-prova empregados nos ensaios foram moldados no teor ótimo de cimento asfáltico referente a cada uma das misturas. Constatou-se a viabilidade técnica da adição de óleo extensor para a incorporação de borracha de pneus descartados em concreto asfáltico, permitindo a obtenção de resultados satisfatórios quanto aos projetos de dosagem das misturas pelo método Marshall. Com base nos resultados dos ensaios realizados, acredita-se ser viável a execução de trechos experimentais empregando as duas misturas modificadas. / Researches on the application of discarded tires in asphaltic pavements has been developed since 1960, mainly in the United States and since the beginning of the 90\'s in Brazil, as an alternative to the reduction of environmental problems created by this kind of solid residues. The purpose of this research is to evaluate the performance of three hot mix asphalt concrete: two using different crumb rubber and shale oil contents (CAP 40 + 12% rubber + 10% shale oil and CAP 40 + 20% rubber + 15% shale oil) and a conventional hot mix asphalt concrete. The research is part of a major program coordinated by the Universidade de São Paulo (EESC-USP), Universidade Estadual de Maringá and Petrobras, comprehending the execution of asphaltic mixtures using tire rubber and shale oil in experimental road segments. The tests performed are: Marshall test, indirect tension, resilient modulus and static creep. The samples tested were compacted in the optimum binder content of each mixture. Good results obtained in tests confirrned the technical viability of using the shale oil as extender in crumb rubber asphalt hot mixtures. The results lead to the conclusion that experimental road sections or segments may be constructed with both tested rubber-oil modified asphalt mixtures.
8

Nouvelles structures électroluminescentes organiques pour applications signalétiques et petits afficheurs / New structures of organic light-emitting diodes for signage applications and displays

Murat, Yolande 11 May 2017 (has links)
La filière OLED (diode électroluminescente organique) est depuis quelques annéesfortement industrialisée notamment depuis leur utilisation dans les smartphones et les téléviseurs.Cependant, les procédés de fabrication, notamment l’évaporation thermique sous vide, restent coûteuxet ne peuvent pas être utilisés pour développer des applications à faible valeur ajoutée (petitsafficheurs, signalétique, éclairage). Ces travaux de thèse ont pour objectif de développer une OLEDperformante et stable fabriquée à coût réduit afin de répondre à cette problématique. La voie liquide aété privilégiée afin de diminuer les coûts de fabrication de l’OLED et il a été choisi de développer unestructure inverse pour améliorer la stabilité. Dans ce travail de thèse, le polymère PEIE(polyéthylénimine éthoxylate) a été utilisé pour diminuer le travail de sortie de la cathode transparente.Nous avons montré qu’il était possible d’atteindre des performances supérieures en structure inversequ’en structure conventionnelle à partir du même polymère émissif, le Super Yellow. Afin desimplifier le procédé de dépôt, nous avons montré qu’un mélange binaire {PEIE et matériau bloqueurde trous} pouvait être déposé en une seule fois tout en conservant un fonctionnement optimal. Uneétude par TOF-SIMS (Spectrométrie de Masse d’Ions Secondaires à Temps de Vol) a permis de mettreen évidence une ségrégation verticale du mélange binaire. Par ailleurs, l’électrode en oxyde d’étainindium(ITO), qui représente généralement plus d’un quart du coût de fabrication, a été remplacéeavec succès par une électrode de SnO2 (oxyde d’étain), déposée par ALD (dépôt de couches mincesatomiques). / OLED (Organic Light-Emitting Diode) technology has been exploited on an industrialscale for several years, principally in smartphones, TV displays, and similar devices. However, currentfabrication processes, such as thermal evaporation under high vacuum, are expensive and cannot beused for low-cost applications (signage, lighting, etc.). This work aims to develop high-performance,stable, low-cost OLEDs. Fabrication by solution processing was chosen to reduce the processing costsin any future commercialization of the work, while the inverted architecture was used to optimizedevice stability. In this work, ethoxylated polyethylenimine (PEIE) was used to reduce the workfunction of the transparent cathode. It was shown that higher performances could be obtained withinverted OLEDs compared to direct devices incorporating the same emissive polymer (Super Yellow).Furthermore, it was demonstrated that a binary blend, (PEIE and a hole blocking material) could bedeposited in a single step without reducing the OLED device’s performance – greatly simplifying thefabrication process. A TOF-SIMS (Time of Flight-Secondary Ion Mass Spectrometry) study wasconducted which demonstrated a vertical phase segregation of the binary blend. Finally, the indiumtinoxide (ITO) electrode, which represents at least 25% of the fabrication cost, was successfullyreplaced with a tin oxide (SnO2) layer, deposited by ALD (Atomic Layer Deposition).
9

Análise dos efeitos da borracha moída de pneu e do resíduo de óleo de xisto sobre algumas propriedades mecânicas de misturas asfáticas densas / Analysis of the effects of crumb rubber and shale-oil residue on mechanical properties of asphalt mixtures

Pilati, Fernanda 27 March 2008 (has links)
No Brasil, desde o início da década de 1990, vêm sendo desenvolvidas pesquisas sobre aplicação do asfalto-borracha visando tanto a diminuição dos problemas ambientais gerados pelo descarte de pneus inservíveis, como a melhoria das características dos ligantes produzidos. Dentro desse contexto, esta pesquisa teve por objetivo avaliar o desempenho mecânico de oito misturas asfálticas do tipo concreto asfáltico usinado a quente, produzidas com asfaltos convencional e convencional modificado com borracha de pneu e resíduo de óleo de xisto. Quanto ao ligante, foram utilizados 8 tipos, a saber: CAP 30/45 (referência); dois ligantes empregando teores diferentes de borracha moída de pneu; outros dois com teores distintos de resíduo de óleo de xisto e, por fim, mais três com combinações de teores de borracha e de resíduo de óleo de xisto. Os corpos-de-prova empregados nos ensaios foram moldados em cinco teores diferentes de ligantes asfálticos (4,5; 5,0, 5,5; 6,0 e 6,5%). Conseqüentemente, foram realizados ensaios Marshall, resistência à tração, módulo de resiliência e umidade induzida. Com base nos resultados dos ensaios realizados observou-se que tanto a borracha quanto o óleo reduzem a resistência à tração e o módulo de resiliência das misturas, no entanto, na recuperação retardada, os efeitos da borracha e do óleo são antagônicos, diminuindo e aumentando, respectivamente. Ademais, quanto à suscetibilidade à ação da água, as misturas com adição de óleo apresentaram menor suscetibilidade que as misturas com adição de borracha. Além disso, foi observado que todas as misturas estudadas, exceto aquelas com altas concentrações de óleo e de borracha, atenderam os requisitos estabelecidos pelas especificações, para as propriedades analisadas. Todavia, em alguns casos, considerando os efeitos antagônicos do óleo e da borracha, algumas combinações entre ambos podem ser realizadas, com a finalidade de alcançar os níveis desejados para as propriedades do ligante asfalto-borracha e das misturas asfálticas. / In Brazil, since the beginning of the 90\'s, have been developed researches on the application of asphalt-rubber seeking the reduction of environmental problems created by the used tires, and the improvement of the characteristics of the produced binder. Taking this into account, the purpose of this research is to evaluate the mechanical performance of eight hot mix asphalt concretes, produced with conventional asphalt and modified asphalt with crumb rubber and shale-oil residue. Eight types of binders were used: CAP 30/45 (reference); two binders using different crumb rubber contents, two with different shale-oil residue contents, and finally three more with the combination of crumb rubber and shale-oil residue contents. The specimens used in the laboratorial tests were compacted in five different binders contents (4.5; 5.0, 5.5; 6.0 e 6.5%). Hence, the tests performed are: Marshall test, indirect tension, resilient modulus and moisture induced. The results showed that the rubber and the shale oil reduce the indirect tension and resilience module of the mixtures, however, on the delayed recover, the effects of the rubber and of the shale oil are opposed, decreasing and increasing it, respectively. Moreover, for the moisture susceptibility, the mixtures with shale-oil residue exhibited less susceptibility to water than those with crumb rubber. Furthermore, all the studied mixtures, except those with high shale-oil residue and rubber concentrations, they got to attend the established requirements for the specifications, for the analyzed properties. Although, in some cases, considering the opposed effects of the shale oil and of the crumb rubber, some combinations between both can be accomplished, with the purpose of reach the levels wanted for the properties of the asphaltrubber binder and the asphalt mixtures. Also regression models were elaborated as for the analyzed properties. The results obtained of modeling were satisfactory.
10

Análise dos efeitos da borracha moída de pneu e do resíduo de óleo de xisto sobre algumas propriedades mecânicas de misturas asfáticas densas / Analysis of the effects of crumb rubber and shale-oil residue on mechanical properties of asphalt mixtures

Fernanda Pilati 27 March 2008 (has links)
No Brasil, desde o início da década de 1990, vêm sendo desenvolvidas pesquisas sobre aplicação do asfalto-borracha visando tanto a diminuição dos problemas ambientais gerados pelo descarte de pneus inservíveis, como a melhoria das características dos ligantes produzidos. Dentro desse contexto, esta pesquisa teve por objetivo avaliar o desempenho mecânico de oito misturas asfálticas do tipo concreto asfáltico usinado a quente, produzidas com asfaltos convencional e convencional modificado com borracha de pneu e resíduo de óleo de xisto. Quanto ao ligante, foram utilizados 8 tipos, a saber: CAP 30/45 (referência); dois ligantes empregando teores diferentes de borracha moída de pneu; outros dois com teores distintos de resíduo de óleo de xisto e, por fim, mais três com combinações de teores de borracha e de resíduo de óleo de xisto. Os corpos-de-prova empregados nos ensaios foram moldados em cinco teores diferentes de ligantes asfálticos (4,5; 5,0, 5,5; 6,0 e 6,5%). Conseqüentemente, foram realizados ensaios Marshall, resistência à tração, módulo de resiliência e umidade induzida. Com base nos resultados dos ensaios realizados observou-se que tanto a borracha quanto o óleo reduzem a resistência à tração e o módulo de resiliência das misturas, no entanto, na recuperação retardada, os efeitos da borracha e do óleo são antagônicos, diminuindo e aumentando, respectivamente. Ademais, quanto à suscetibilidade à ação da água, as misturas com adição de óleo apresentaram menor suscetibilidade que as misturas com adição de borracha. Além disso, foi observado que todas as misturas estudadas, exceto aquelas com altas concentrações de óleo e de borracha, atenderam os requisitos estabelecidos pelas especificações, para as propriedades analisadas. Todavia, em alguns casos, considerando os efeitos antagônicos do óleo e da borracha, algumas combinações entre ambos podem ser realizadas, com a finalidade de alcançar os níveis desejados para as propriedades do ligante asfalto-borracha e das misturas asfálticas. / In Brazil, since the beginning of the 90\'s, have been developed researches on the application of asphalt-rubber seeking the reduction of environmental problems created by the used tires, and the improvement of the characteristics of the produced binder. Taking this into account, the purpose of this research is to evaluate the mechanical performance of eight hot mix asphalt concretes, produced with conventional asphalt and modified asphalt with crumb rubber and shale-oil residue. Eight types of binders were used: CAP 30/45 (reference); two binders using different crumb rubber contents, two with different shale-oil residue contents, and finally three more with the combination of crumb rubber and shale-oil residue contents. The specimens used in the laboratorial tests were compacted in five different binders contents (4.5; 5.0, 5.5; 6.0 e 6.5%). Hence, the tests performed are: Marshall test, indirect tension, resilient modulus and moisture induced. The results showed that the rubber and the shale oil reduce the indirect tension and resilience module of the mixtures, however, on the delayed recover, the effects of the rubber and of the shale oil are opposed, decreasing and increasing it, respectively. Moreover, for the moisture susceptibility, the mixtures with shale-oil residue exhibited less susceptibility to water than those with crumb rubber. Furthermore, all the studied mixtures, except those with high shale-oil residue and rubber concentrations, they got to attend the established requirements for the specifications, for the analyzed properties. Although, in some cases, considering the opposed effects of the shale oil and of the crumb rubber, some combinations between both can be accomplished, with the purpose of reach the levels wanted for the properties of the asphaltrubber binder and the asphalt mixtures. Also regression models were elaborated as for the analyzed properties. The results obtained of modeling were satisfactory.

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