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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.
21

Utilização do politereftalato de etileno (PET) em misturas asfálticas.

SILVA, José de Arimatéia Almeida e. 05 June 2018 (has links)
Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-06-05T00:24:48Z No. of bitstreams: 1 JOSÉ DE ARIMATÉIA ALMEIDA E SILVA – TESE (PPGEP) 2015.pdf: 6946608 bytes, checksum: 04efbba58513fb4cbcc2225d2ade0888 (MD5) / Made available in DSpace on 2018-06-05T00:24:48Z (GMT). No. of bitstreams: 1 JOSÉ DE ARIMATÉIA ALMEIDA E SILVA – TESE (PPGEP) 2015.pdf: 6946608 bytes, checksum: 04efbba58513fb4cbcc2225d2ade0888 (MD5) Previous issue date: 2015-06-26 / Capes / A adição do resíduo de Politereftalato de Etileno (PET) em Cimentos Asfálticos de Petróleo (CAP), triturados em partículas cujo diâmetro está entre 0,6 e 0,074 mm, pode ser uma alternativa técnica viável para melhorar as propriedades mecânicas e reológicas das misturas asfálticas. Esta adição tem como finalidade proporcionar uma menor susceptibilidade das misturas asfálticas a fadiga e, conseqüentemente aumentar a vida útil de revestimentos asfálticos em regiões com clima tropical e a temperaturas elevadas. Este trabalho tem como objetivo principal a incorporação de um aditivo no Cimento Asfáltico de Petróleo. A adição de PET foi realizada em proporções de 4%, 5% e 6% relativas ao peso do teor de CAP ótimo e mensuradas as propriedades volumétricas e mecânicas. Além disso foram realizados análises físicas e reológicas do CAP puro e modificado. De acordo com os resultados obtidos nesta pesquisa pode -se inferir que o PET micronizado pós consumo corresponde a um polímero melhorador das propriedades reológicas do CAP 50/70, em termos de rigidez, proporcionado a mistura asfáltica um incremento no comportamento mecânico a luz dos ensaios de Resistência à Tração por Compressão Diametral, Módulo de Resiliência, Resistência por Umidade Induzida, Flow Number e Ruptura por Fadiga. É possível aceitar que “o resíduo do PET micronizado, no teor de 5% pode ser utilizado como agente modificador do CAP e, que o mesmo e capaz de promover ganhos nas Propriedades Mecânicas de Revestimentos Asfálticos. / The addition of polyethylene terephthalate (PET) waste in binder, crushed into particles whose diameter is between 0.074 and 0.6 mm, may be a viable alternative technique to improve the mechanical and rheological properties of asphalt mixtures . This addition is intended to provide a lower susceptibility of fatigue in asphalt mixtures and consequently improve the durability of asphalt mixtures in regions with tropical climate and high temperatures. This work has the objective the incorporation of an additive in binder. It was add in proportions of 4% 5% and 6% relative to the weight of the optimum binder content and it was measured volumetric and mechanical properties of asphalt mixtures. Also performed were physical and rheological analysis of pure and modified binder. According to the results obtained in this study can be inferred that the micronized PET improve the performance of binder 50/70. The addition of PET provided an increase in the mechanical behavior in the Indirect Tensile Strength, Resilient Modulus, Moisture susceptibility, Flow Number and Fatigue life. It is possible to accept that the use of 5% micronized PET waste may be used as modifying agent of binder, and that it improve mechanical properties of asphalt mixtures.
22

Efeitos da cimentação e da morfologia na condutividade hidráulica e na resistência mecânica de empacotamentos binários / Effects of cementation and morphology in hydraulic conductivity and mechanical strength of binaries packing systems

Viana, Lucimar Arruda 10 April 2013 (has links)
Made available in DSpace on 2015-03-26T13:28:15Z (GMT). No. of bitstreams: 1 texto completo.pdf: 2140887 bytes, checksum: c11c1548ce3cc21faa5903962434d637 (MD5) Previous issue date: 2013-04-10 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The main focus of this work was to study the influence of physical properties and of a cementing agent in structuring the sand fraction of a sandy soil, considering binaries packing systems applied to glass spheres and to a soil artificially prepared from two natural soils sand fractions. The study covered the following topics: (i) to establish packing curves for binary systems of the artificial soil and glass spheres; (ii) to characterize the mechanical strength and hydraulic conductivity of binary systems of the artificial soil; (iii) to study the influence of the cementing agent Hydrated lime in the artificial soil binary packing systems; (iv) to verify the influence of the artificial soil morphological properties through the comparison of the results of the present testing program and previous research including the parameters density, penetration resistance and soil hydraulic conductivity; and (v) to develop and operationalize a system for capturing images of grains of sand. The soil samples were subjected to pre-treatment for obtaining clean sand fractions which were separated by sieving through twenty-one sieve classes encompassing the diameter range of 0.053 to 2.000 mm. Sequentially, morphometric characterization tests were carried out in the sand fractions, as well as binary packing studies were performed in the sand fractions and in the glass spheres. The main results were: (i) binaries packing of glass spheres and artificial soil clean sand fractions reached a point of maximum density in a composition of approximately 30% of smaller particles; (ii) binaries packing of glass spheres showed larger density gains until the relationship between the larger diameter (D) and the minor diameter (d) was close to 6, and above this value, increases in density occurred to a lesser proportion; (iii) binaries packing of artificial soil sand fractions occurred similarly to binaries packing of glass spheres, but with larger gains until the relationship between the larger diameter (D) and the minor diameter (d) was close to 8; (iv) the hydraulic conductivity and tip penetration resistance of artificial soil binaries packing decreased when increasing the ratio D/d; (v) the cementation by Hydrated lime reduced hydraulic conductivity and increased the tip penetration resistance of the artificial soil binaries packing; (vi) the morphology of the particles influenced significantly the density, hydraulic conductivity and tip penetration resistance of the artificial soil clean sand fraction binaries packing; and (vii) the system developed for the capture of images of sand grains worked properly, with practicality. / Este trabalho direcionou-se ao estudo da influência das propriedades físicas e de um agente de cimentação na estruturação da fração areia de um solo arenoso, considerando-se sistemas de empacotamentos binários aplicados a esferas de vidro e a um solo artificialmente preparado a partir das frações areias de dois solos naturais. A pesquisa abrangeu os seguintes tópicos: (i) estabelecer curvas de empacotamento para sistemas binários do solo artificial e de esferas de vidro; (ii) caracterizar a resistência mecânica e a condutividade hidráulica dos sistemas binários do solo artificial; (iii) estudar a influência do agente de cimentação cal hidratada nos sistemas de empacotamentos binários do solo artificial; (iv) verificar a influência das propriedades morfológicas através da comparação dos resultados do presente estudo e de trabalho prévio, considerando parâmetros como densidade de empacotamento, resistência à penetração e condutividade hidráulica; e (v) desenvolver e tornar operacional um sistema para a captura de imagens de grãos de areia. As amostras de solo foram submetidas a prétratamentos para obtenção da fração areia limpa e posterior peneiramento para separação em vinte e uma classes, entre os diâmetros de 0,053 e 2,000 mm. Sequencialmente, foram realizados ensaios de caracterização morfométrica das suas frações areia, sendo também realizados estudos de empacotamentos binários em esferas de vidro e nas mesmas. Os principais resultados obtidos foram: (i) empacotamentos binários das esferas de vidro e das frações areia limpa do solo artificial atingiram um ponto de máxima densidade em uma composição aproximada de 30% de partículas menores; (ii) empacotamentos binários das esferas de vidro apresentaram ganhos maiores de densidade até relações entre o diâmetro maior (D) e o diâmetro menor (d) próximas a 6, sendo que acima desse valor, aumentos ocorreram em menor proporção; (iii) empacotamentos binários das frações areia do solo artificial ocorreram de forma similar aos empacotamentos binários de esferas de vidro, mostrando-se mais eficiente em relação à elevação da densidade quando a razão D/d se aproximou de 8; (iv) a condutividade hidráulica e a resistência de ponta à penetração dos empacotamentos binários do solo artificial sofreram reduções à medida que se aumentou a relação D/d; (v) a cimentação por cal hidratada reduziu a condutividade hidráulica e elevou a resistência de ponta à penetração dos empacotamentos binários do solo artificial; (vi) a morfologia das partículas influenciou significativamente a densidade, condutividade hidráulica e resistência de ponta à penetração dos empacotamentos binários da fração areia limpa do solo artificial; e (vii) o sistema desenvolvido para a captura das imagens de grãos de areia funcionou de forma adequada, com praticidade.
23

Efeitos da cal hidratada e do ácido polifosfórico nas propriedades mecânicas e suscetibilidade à umidade de misturas asfálticas densas / Effects of hydrated lime and polyphosforic acid in mechanical properties and moisture susceptibility in dense asphalt mixtures

Wilson Ricardo de Grande 06 June 2011 (has links)
Esta pesquisa teve por objetivo analisar os efeitos da cal hidratada e do ácido polifosfórico nas propriedades mecânicas e suscetibilidade à umidade de misturas asfálticas densas. O ligante utilizado foi o CAP 50/70, chamado de controle, modificado com 0,6 e 1,2% de PPA, e como aditivo a cal hidratada em concentrações de 1,5 e 3,0%, perfazendo nove combinações de misturas asfálticas. Foram moldados 108 corpos-de-prova, divididos em 4 e 7% de volume de vazios, sendo que os corpos-de-prova de 7% foram divididos em condicionados e não condicionados. Os ensaios realizados para análise das propriedades mecânicas foram o Módulo de Resiliência e a Resistência à Tração Indireta. Os resultados mostram que o aumento da concentração de ácido polifosfórico melhora a rigidez e a flexibilidade, e melhora a suscebilidade ao dano por umidade, assim como aumenta a resistência à tração; para a cal hidratada, com o aumento da sua concentração, ocorreu aumento da rigidez e da flexibilidade de maneira mais discreta, se comparado ao ácido polifosfórico, e proporciona a diminuição da resistência à tração: o teor que apresentou melhor suscetibilidade ao dano por umidade foi de 1,5% de cal hidratada. / This work aims to analyze the effects of hydrated lime and polyphosphoric acid on the mechanical properties and moisture susceptibility of dense asphalt mixtures. In nine combinations of asphalt mixtures, CAP 50/70, named control and modified with 0,6 and 1,2% of PPA, was employed as binder, and hydrated lime in concentrations of 1,5 and 3,0% was used as additive. 108 test specimens have been molded and divided into 4 and 7% of volume void, considering that 7% were separated into conditioned and non-conditioned. The Resilient Modulus and the Tensile Strength were the tests conducted for the analysis of mechanical properties. The results showed that the increase in polyphosphoric acid concentration improved stiffness and flexibility and increased the susceptibility to moisture damage, as well as the tensile strength. Also in the results, with the concentration increase of the hydrated lime, there was a smaller increase of stiffness and flexibility, and it provided a decrease of tensile strength, considering that the percentage of 1,5% of hydrated lime presented the best susceptibility to moisture damage.
24

Contribuição ao estudo da deformação permanente de misturas asfálticas densas à luz de ensaios de fluência por compressão uniaxial estática e dinâmica / Contribution for the rutting study on hot mixture asphalt by means of static and dynamic creep tests

Andressa Ka Yan NG 17 January 2013 (has links)
Esta dissertação apresenta um estudo da deformação permanente de misturas asfálticas à luz dos resultados de ensaios de fluência por compressão uniaxial estática e dinâmica. Para isso, um programa experimental completo foi desenvolvido combinando fatores relacionados às misturas asfálticas e às condições de ensaio. Foram produzidos corpos de prova de misturas asfálticas densas tipo CAUQ com asfalto convencional (CAP 50/70) e com asfalto modificado com polímero SBS (CAP 50/70+SBS), variando o volume de vazios em dois níveis, 4 e 7%, e a presença de aditivo em dois níveis, sem e com cal hidratada. Os corpos de prova foram submetidos a ensaios de fluência com carregamentos estático e dinâmico em dois níveis de tensões, 0,1 MPa e 0,4 MPa, e em duas temperaturas diferentes, 40 e 50ºC. Essas condições do programa experimental permitiram observar o efeito do modificador SBS, da presença da cal e do volume de vazios nas misturas asfálticas, e entender o efeito da temperatura, do nível de tensão e do tipo de carregamento no comportamento de cada tipo de mistura asfáltica. Os resultados indicam que (i) a adição da cal promoveu redução de deformação acumulada somente nas misturas com ligante convencional (CAP 50/70); (ii) as misturas com volume de vazios de 7% apresentam maiores acúmulos de deformação permanente independente da presença de cal, do tipo de carregamento e da temperatura do ensaio, sendo maiores para a mistura asfáltica com CAP 50/70; (iii) as misturas com ligante modificado se mostraram menos sensíveis às variações da temperatura e do nível de tensão; (iv) e a melhora das características das misturas com asfalto modificado com polímero é detectada somente a partir de ensaios dinâmicos. / This paper presents a study of rutting on hot mixture asphalt (HMA) by means of static and dynamic creep tests. A full factorial experiment was developed considering factors related to HMA and to the test conditions. It was produced HMA (unmodified (CAP 50/70) and SBS modified binders) specimens at two different air voids (4 and 7%) and with or without hydrated lime. The specimens were submitted to static and dynamic creep tests at two stress levels, 0,1 MPa e 0,4 MPa, and two temperatures, 40 e 50ºC. These conditions of the experimental program allowed to observe the effects of the modifier SBS, the presence of the lime and the air voids in HMA, and to understand the effects of the temperature, stress and the type of loading on the behavior of each type of asphalt mix. The results indicate that (i) the addition of lime promoted reduction of accumulative deformation only in mixtures with conventional binder (CAP 50/70), (ii) mixtures with 7% air voids showed greater accumulation of permanent deformation regardless of presence of lime, the type of load and temperature of the test, mainly for the conventional HMA, (iii) the Polymer Modified Asphalt Hot Mix Asphalt (PMA-HMA) were less sensitive to temperature and the stress variation (iv) the improvement of the polymer modified asphalt mixture characteristics (PMA-HMA) were detected only on dynamic load conditions.
25

The limits of partial life cycle assessment studies in road construction practices: A case study on the use of hydrated lime in Hot Mix Asphalt

Schlegel, T., Puiatti, D., Ritter, H.-J., Lesueur, D., Denayer, C., Shtiza, A. 23 September 2020 (has links)
Extensive published literature shows that hydrated lime improves Hot Mix Asphalt (HMA) durability. Its impact on the environmental impact of HMA has not been investigated. This paper presents a comparative Life Cycle Assessment (LCA) for the use of HMA without hydrated lime (classical HMA) and with hydrated lime (modified HMA) for the lifetime of a highway. System boundaries cover the life cycle from cradle-to-grave, meaning extraction of raw materials to end of life of the road. The main assumptions were: 1. Lifetime of the road 50 years; 2. Classical HMA with a life span of 10 years, maintenance operations every 10 years; 3. Modified HMA with an increase in the life span by 25%, maintenance operations every 12.5 years. For the lifetime of the road, modified HMA has the lowest environmental footprint compared to classical HMA with the following benefits: 43% less primary total energy consumption resulting in 23% lower emissions of greenhouse gases. Partial LCAs focusing only on the construction and/or maintenance phase should be used with caution since they could lead to wrong decisions if the durability and the maintenance scenarios differ. Sustainable construction technologies should not only consider environmental impact as quantified by LCA, but also economic and social impacts as well. Avoiding maintenance steps means less road works, fewer traffic jams and hence less CO2 emissions.
26

Control of stack emissions using hydrated lime injections during incineration of healthcare risk waste : a case study of Biomed in Benoni

Themba, Nomathemba 01 1900 (has links)
Abstract in English / Incineration is still a widely utilised method for treating healthcare risk waste in the Republic of South Africa. As much as incinerators are needed, the fact that they are still a critical source of hazardous toxic air pollutants that are not easy to manage cannot be disregarded. The Ministry of Environmental Affairs has promulgated a new regulation for General and Hazardous Waste Thermal Treatment. This exceedingly stringent air pollution legislation requires that existing incinerators be modified or redesigned to meet the new air quality standards, or face closure in the event that they fail to comply. The regulation contains strict emission requirements for concentrations of stack gases such as CO2, NO2, NOx, HCl, HF, CO, SO2, as well as TOC and PM. To be certain that emissions are within the standard, incineration facilities are instructed to reduce the acid gas emissions and to have permanent on-line monitoring equipment for stack testing of regulated pollutants. Since the promulgation of the new legislation in April 2015, none of the incinerators in South Africa has been able to achieve the new requirements. This study, based on the quantitative approach, was conducted in search of a cost-effective method of controlling acid gas emissions from incinerators without major adjustments to the plants. During the study, 60 kg of sorbacal Ca(OH)2 was injected into a lime feeder every day. A variable speed drive was used to inject Ca(OH)2 into the furnace continuously at a rate of between 2.5 kg/h and 3.5 kg/h. The temperature was maintained between 850°C and 1200°C with the use of four gas burners. Two manual blowers were utilised to ensure a continuous flow of Ca(OH)2 into the reaction chamber and filtration system. Comparative analysis was done to compare gas emission levels before and after the use of hydrated lime. Descriptive statistics were used to compute the mean, frequency and percentages, while Wilcoxon sign rank test established whether hydrated lime was significant in reducing gaseous emissions or not. Wilcoxon sign rank test showed a statistically significant difference (P<0.05) in the reduction of all gaseous emissions using hydrated lime, except particulate matter where there was a significant increase in emissions. This technology was able to achieve high removal efficiency of 97% for HCl, 86% for HF, 83% for NOx, 87% for SO2 and 74% for NO2. The optimum temperature for SO2 and NOx was 1020°C. For HCl it was between 1190°C and 1200°C, and for NO2 it was between 1120°C and 1200°C. The amount of particulate matter increased along with the concentration of the Ca(OH)2 injections. Ca(OH)2 was found to be cost effective in the controlling and capturing of gaseous emissions. It is recommended that combustion requirements, such as heat, oxygen and turbulence, be considered to reduce the amount of gases generated during the incineration of healthcare risk waste. It is also recommended that electrostatic precipitators be used instead of fabric filters to improve the efficiency of capturing the particulate matter. / Environmental Sciences / M.Sc. (Environmental Science)
27

Investigação da relação entre parâmetros da compactação giratória e de deformação permanente em misturas asfálticas densas / Investigation of relationship between the gyratory compaction and rutting parameters of asphalt mixtures

Soares, Jéssica Santiago 08 August 2014 (has links)
Esta pesquisa tem como objetivo estudar a relação entre parâmetros de compactação e de deformação permanente à luz dos ensaios de compactação giratória Superpave ® e de ensaios de compressão uniaxial estática e dinâmica. Foram estudadas 8 misturas asfálticas com a mesma granulometria (Faixa C) e tipo de agregado mineral (granito) porém variou-se o ligante asfáltico (CAP 50/70 e CAP 50/70+SBS), o volume de vazios (4% e 7%) e a adição de cal hidratada. A partir dos resultados do ensaio de compactação observou-se que a inclinação das curvas de compactação das misturas compactadas a 7% foram mais acentuadas do que as de 4% e os parâmetros incidentais deste ensaio foram sensíveis à presença de cal e à variação do asfalto das misturas testadas. Quanto aos resultados dos ensaios de creep estático e dinâmico, notou-se que as misturas com Vv de 4% e as com asfalto modificado apresentam menor suscetibilidade à deformação permanente, no entanto, essas vantagens do asfalto modificado foram observadas somente nos ensaios de creep dinâmico. No que se refere às relações entre os parâmetros de compactação e de deformação permanente, os ajuste não se mostraram promissores como verificado pela qualidade dos ajustes (R2) exceto para algumas relações com CDI e TDIm. / This research aims to study relations between compaction and permanent deformation by means of Superpave® gyratory compaction and static and dynamic creep tests. Thus, eight asphalt mixtures were evaluated which were composed by same type (granite) and gradation (dense) of mineral aggregate but two types of asphalt binder (Pen 50/70 AC and Pen 50/70+SBS AC), two different levels of air voids (4% and 7%) and the addition of hydrated lime. Compaction results indicated that curve slopes of 7% air void asphalt mixtures were stronger than the 4% ones, and compaction parameters were sensitive to lime addition and asphalt type change. Static and dynamic creep test results indicated that 4% air void and modified asphalt mixtures presented lower susceptibility to rutting, but, these modified asphalt advantages were observed only in dynamic creep tests. In regard to relation between compaction and rutting parameters, linear models did not fit accurately, excepting some CDI and TDIm ones.
28

Investigação da relação entre parâmetros da compactação giratória e de deformação permanente em misturas asfálticas densas / Investigation of relationship between the gyratory compaction and rutting parameters of asphalt mixtures

Jéssica Santiago Soares 08 August 2014 (has links)
Esta pesquisa tem como objetivo estudar a relação entre parâmetros de compactação e de deformação permanente à luz dos ensaios de compactação giratória Superpave ® e de ensaios de compressão uniaxial estática e dinâmica. Foram estudadas 8 misturas asfálticas com a mesma granulometria (Faixa C) e tipo de agregado mineral (granito) porém variou-se o ligante asfáltico (CAP 50/70 e CAP 50/70+SBS), o volume de vazios (4% e 7%) e a adição de cal hidratada. A partir dos resultados do ensaio de compactação observou-se que a inclinação das curvas de compactação das misturas compactadas a 7% foram mais acentuadas do que as de 4% e os parâmetros incidentais deste ensaio foram sensíveis à presença de cal e à variação do asfalto das misturas testadas. Quanto aos resultados dos ensaios de creep estático e dinâmico, notou-se que as misturas com Vv de 4% e as com asfalto modificado apresentam menor suscetibilidade à deformação permanente, no entanto, essas vantagens do asfalto modificado foram observadas somente nos ensaios de creep dinâmico. No que se refere às relações entre os parâmetros de compactação e de deformação permanente, os ajuste não se mostraram promissores como verificado pela qualidade dos ajustes (R2) exceto para algumas relações com CDI e TDIm. / This research aims to study relations between compaction and permanent deformation by means of Superpave® gyratory compaction and static and dynamic creep tests. Thus, eight asphalt mixtures were evaluated which were composed by same type (granite) and gradation (dense) of mineral aggregate but two types of asphalt binder (Pen 50/70 AC and Pen 50/70+SBS AC), two different levels of air voids (4% and 7%) and the addition of hydrated lime. Compaction results indicated that curve slopes of 7% air void asphalt mixtures were stronger than the 4% ones, and compaction parameters were sensitive to lime addition and asphalt type change. Static and dynamic creep test results indicated that 4% air void and modified asphalt mixtures presented lower susceptibility to rutting, but, these modified asphalt advantages were observed only in dynamic creep tests. In regard to relation between compaction and rutting parameters, linear models did not fit accurately, excepting some CDI and TDIm ones.
29

Vápenné malty modifikované jemně mletým cihelným střepem / Lime Mortars Modified by Fine Ground Brick Body

Šmerdová, Ludmila January 2013 (has links)
Natural pozzolanic materials played an important role in Ancient architecture. In the last decades and nowadays it is artifical pozzolan which especially finds its use as an additive to mortar and concrete to improve some, especially the mechanical properties. This master thesis deals with study of pozzolan type of fine brick powder which is a by-product of the production of calibrated bricks. Along with studying pozzolanic activity of brick powder, lime mortar with different proportions of brick powder as an additive or replacement of lime dust are investigated. What is observed is its impact on the consistency of these mortar, water absorption, strength in time or fracture-mechanical parameters of mortar. The results may indicate the possible potential use of this source of pozzolanic admixture in lime mortar and plaster which are nowadays mainly used for the restoration of facades of historic buildings.

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