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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.
51

Reaproveitamento de finos de pedreiras em pavimentação: uma abordagem técnica e econômica / Reusing of fine quarries in paving: a technical and economical approach

SILVEIRA, Leonardo Ramos da 23 February 2010 (has links)
Made available in DSpace on 2014-07-29T15:01:52Z (GMT). No. of bitstreams: 1 Dissertacao_Leonardo PPGEMA_2010_part 1.pdf: 1765624 bytes, checksum: 3dcc9e66423433d5b3ccd27a56e7db98 (MD5) Previous issue date: 2010-02-23 / The wastes generated by the quarry companies from civil construction represent an activity that has been outstanding because of the countless problems that appear with their stockpiling and maintenance. The great concern with those wastes is linked to the capacity to generate social and environmental effects that can harm the ambient through the appearance of environmental impacts. In this context, researches have been done to study the application of those wastes in paving works, with the propose to reduce the generated problems and to contribute for the appearance of materials that can substitute those that are considered traditional and that are more and more scarce. The objective of this research was to verify the technical and economical viability of the use of quarry wastes in paving, besides complementing the researches previously done with those wastes. For this research the same mixtures used in the experimental pavement were analyzed at laboratory: Mixture 1 (30% filler + 70% soil), Mixture 2 (20% filler + 80% soil), Mixture 3 (20% micaxist powder + 80% soil) and Mixture 4 (30% micaxist powder + 70% soil). In the complementally evaluation, tests of chemical characterization (soil and mixtures), X-ray diffraction and electronic microscopy of sweeping were done. For technical investigation, the experimental pavement evaluation was done in two different periods using load bearing plate test, dynamic cone penetration and Benkelman beam. The economical viability analysis was done by the costs estimated for the execution of each experimental sub-section, simulating different sceneries. The results of the chemical characterization demonstrated that there is an increment of parameters as pH and cation exchange capacity with the incorporation of fine quarries to the soil. The results of X-ray diffraction showed that new minerals are not formed in the mixtures. The results of microscopy of sweeping pointed that the factors that more influences in the mixtures structures are their grain size materials and the compaction energy applied. In the experimental pavement evaluation it was possible to verify the influence of the rain in the pavement structural performance, what provoked high displacements values for the right board. Even so, the sub-sections executed with filler and micaxist powder have been presenting behavior varying among regular and good. In the costs estimated results, it was observed that the sub-sections executed with fine quarry wastes can be considered the most economical, mainly when the minimum distance of competition is considered. Being like this, one can be noted that the reusing of fine quarry wastes in pavements has viability and it contributes significantly for the reduction of environmental effects generated by the mineral sector. / Os resíduos gerados pelas empresas mineradoras da construção civil representam uma atividade que tem ganhado destaque pelos inúmeros problemas advindos da estocagem e manutenção de seus depósitos. A grande preocupação em torno desses resíduos está ligada à capacidade de gerar externalidades sócio-ambientais que podem prejudicar o meio através do surgimento de impactos ambientais. Neste contexto, têm surgido pesquisas que visam a aplicação desses resíduos em obras de pavimentação, cujo objetivo principal é diminuir os problemas gerados e contribuir para o surgimento de materiais que possam substituir aqueles que são considerados tradicionais e que estão cada vez mais escassos. O objetivo desta pesquisa foi verificar a viabilidade técnica e econômica da utilização de resíduos de pedreiras em pavimentação, além de complementar as pesquisas realizadas anteriormente com esses resíduos. Para tanto, foram analisadas, em laboratório as mesmas misturas empregadas durante a execução do trecho experimental, sendo denominadas de Mistura 1 (30% fíler + 70% solo), Mistura 2 (20% fíler + 80% solo), Mistura 3 (20% pó de micaxisto + 80% solo) e Mistura 4 (30% pó de micaxisto + 70% solo). Na avaliação complementar, foram realizados ensaios de caracterização química (solo e misturas), difração de raios-X e microscopia eletrônica de varredura. Para avaliação técnica, realizou-se o monitoramento do trecho experimental em dois períodos distintos por meio dos ensaios de prova de carga sobre placa, penetrômetro dinâmico de cone e viga Benkelman. Já na análise de viabilidade econômica, foi utilizada a estimativa de custos gerada para a execução de cada sub-trecho, simulando diferentes cenários. Os resultados da caracterização química demonstraram que ocorre um incremento de parâmetros como pH e capacidade de troca catiônica com a incorporação de finos de pedreira ao solo. Os resultados de difração de raios-X mostraram que não há formação de novos minerais nas misturas. Os resultados de microscopia eletrônica de varredura apontaram que os fatores que mais influenciam na estruturação das misturas são a granulometria de seus constituintes e a energia de compactação aplicada. No acompanhamento do trecho experimental foi possível verificar a influência da chuva no desempenho estrutural do pavimento, o que provocou elevados valores de deslocamentos para o bordo direito. Mesmo assim, os sub-trechos executados com fíler e pó de micaxisto têm apresentado comportamento variando entre regular e bom. Nos resultados de estimativa de custos, observou-se que os sub-trechos executados com resíduos finos de pedreira podem ser considerados os mais econômicos, principalmente quando é considerada a distância mínima de competição. Sendo assim, conclui-se que o eaproveitamento de resíduos finos de pedreira em obras de pavimentação é viável e contribui significativamente na redução das externalidades ambientais geradas pelo setor mineral.
52

O uso de redes neurais artificiais como ferramenta para auxiliar na determinação da vida útil de pavimentos flexíveis / Using artificial neural networks as a tool to assist in the evaluation of the remaining life of flexible pavements

Flavio Serpa Zanetti 28 March 2008 (has links)
Este trabalho apresenta um procedimento para auxiliar na determinação da vida útil de pavimentos flexíveis através da determinação de tensões e deformações causadas pela solicitação de um eixo padrão na estrutura de pavimentos flexíveis utilizando Redes Neurais Artificiais. Para treinamento e validação das redes foram utilizadas bacias de deflexões hipotéticas geradas com o auxílio do programa ELSYM5, simulando o carregamento com falling weight deflectometer. Foram criados quatro conjuntos de bacias hipotéticas, dois para pavimentos de três camadas e dois para pavimentos de quatro camadas. As redes neurais artificiais foram treinadas e validadas utilizando-se o simulador EasyNN-plus, que utiliza redes multilayer perceptron com algoritmo de aprendizagem backpropagation. Os dados de entrada das redes são as espessuras das camadas do pavimento e a bacia de deflexão. Como saída, têm-se as tensões e deformações na face inferior do revestimento e no topo do subleito e os módulos de resiliência das camadas do pavimento. Foram determinadas retas de regressão, coeficientes de regressão e histogramas de erros entre os valores reais (ELSYM5) e os valores previstos (RNA). Os resultados obtidos pelas redes neurais artificiais apresentaram boa correlação com os valores reais, demonstrando a capacidade das redes neurais para auxiliar na determinação da vida útil de pavimentos flexíveis, ao estimar diretamente as tensões e deformações em pontos específicos da estrutura. / This paper presents a procedure to assist the evaluation of the remaining life of flexible pavements by means of the determination of stresses and strains caused by a standard load in flexible pavements structures using artificial neural networks. Hypothetical deflections basins, generated by the ELSYM5 program, simulating the load applied by a falling weight deflectometer, were used to train and to validate the networks. Four sets of hypothetical basins were created, two for pavements with three layers and two for pavements with four layers. The artificial neural networks were trained and validated using the EasyNN-plus simulator, which uses multilayer perceptron networks with back-propagation learning algorithm. The networks input data are the pavements layers thickness and the deflection basin. The networks outputs are the stresses and strains in the bottom of the asphalt layer and at the top of the subgrade and resilience modulus of the pavement layers. The results obtained by the artificial neural networks showed good correlation with the real values, demonstrating that neural networks have capacity to assist in the evaluation of the remaining life of flexible pavements, estimating directly the stresses and strains of specific points of the pavement structure.
53

Experimental and analytical study of the reinforcement of pavements by glass fibre grids / Étude du renforcement des infrastructures routières par des grilles en fibre de verre

Sagnol, Loba 15 December 2017 (has links)
Cette thèse traite de l’effet des grilles en fibre de verre, utilisées pour renforcer les structures routières, sur la liaison entre deux couches d’enrobés bitumineux, la durée de vie en fatigue et le module de rigidité des ´éprouvettes cylindriques renforcées, ainsi que sur les déflexions mesurées sur une section de route renforcée in situ. Des essais de cisaillement (LEUTNER) ainsi que de module et de fatigue (ITT) ont été conduit sur des éprouvettes renforcées et non renforcées en utilisant différentes grilles, différentes émulsion ainsi que différentes quantités d’émulsion. Pour ces essais, une surface de test a été construite in-situ, de laquelle les ´éprouvettes ont ´été extraites. Une section de route in-situ a ´également été construite, renforcée avec 3 différentes grilles et avec deux sections de références. Les déflexions de la chaussée ont été déterminées avant et après les travaux. Une modélisation de la structure a été faites basée sur les résultats des mesures de déflexion. / This PhD-study evaluates the impact of glass fibre grids, used to reinforced asphalt structures, on the bonding between two asphalt layers, the fatigue life and the stiffness modulus of reinforced cylindrical specimens as well as on the deflections measured on a reinforced in-situ road section. Shear tests (LEUTNER) as well as modulus-tests and fatigue-tests (ITT) were conducted on reinforced and unreinforced specimens, using different grids, different emulsions and different emulsion quantities. For this tests, an outdoor test-surface was constructed, from which the specimens were extracted. A in-situ road test section was also constructed, reinforced with 3 different grids and having two reference sections. The deflections of the road were determined before and after the construction works. A modelisation of the structure, based on the deflection measurements, was made.
54

Rubber tyre and plastic waste use in asphalt concrete pavement

Onyango, Felix Odhiambo 12 1900 (has links)
M. Tech. (Civil Engineering, Faculty of Engineering and Technology), Vaal University of Technology) / Modified asphalt concrete is one of the important construction materials for flexible pavements. The addition of polymers and natural hydrocarbon modifiers to enhance the properties of asphalt concrete over a wide temperature range in paving applications has been the common practice. Currently these modified asphalt mixtures are relatively expensive. However, recycled polymers and rubber added to asphalt have also shown similar results in improving the performance of road pavements. In this study, an attempt has been made to use low density polyethylene (LDPE) obtained from plastic waste and crumb rubber obtained from worn out vehicle tyres. The aim was to optimise the proportions of LDPE in the bitumen binder using the ‘wet process’ and crumb rubber aggregates in the hot mix asphalt (HMA) using the ‘dry process’. The Marshall method of bituminous mix design was carried out for varying percentages of LDPE namely 2%, 4%, 6%, 8% and 10% by weight of bitumen binder and 1%, 2%, 3%, 4% and 5% crumb rubber by volume of the mineral aggregates. The characteristics of bitumen modified with LDPE were evaluated. The modified asphalt mix was also evaluated to determine the different mix characteristics. The results from laboratory studies in terms of the rheological properties of the LDPE modified bitumen binder showed an increase in viscosity, softening point and stiffness of the binder. The optimum Marshall stability values for HMA mixtures containing 2% crumb rubber tyre and 4% LDPE were found to be 30% higher than the conventional asphalt concrete mix. The wheel tracking test done at 50ºC was 9.81mm rut depth showing a good rutting resistance of the optimized mixture compared to the conventional asphalt mixes. The Modified Lottman test gave a Tensile Strength Ratio value of 0.979 which indicates a low degree of moisture susceptibility of the modified asphalt mix. The above results showed improved properties of the asphalt mixture. The economic assessment done using the present worth of costs indicated a reduction in maintenance cost due to the extended service life of the modified asphalt pavement.
55

Modélisation avancée du contact pneu-chaussée pour l'étude des dégradations des chaussées en surface / Advanced Modeling of Tire-Pavement Contact to Investigate Pavement Surface Degradation

Manyo, Edem Yawo 14 February 2019 (has links)
L'apparition récente de nouveaux matériaux dans les structures de chaussée associée à une diminution de l'épaisseur des couches de surface et une augmentation du chargement des poids lourds et de leur fréquence de passage a entrainé de nouvelles pathologies de dégradation. Outre les problèmes d'orniérage bien connus, apparaissent désormais des fissures descendantes (top down cracking) ainsi que des problèmes de décohésion aux interfaces. Ces nouvelles pathologies entrainent des dépenses considérables sur l'ensemble du réseau (environ 15 milliards d'euros par an), particulièrement en zones urbanisées plus sujettes aux dégradations de surface et ne permettent pas d'estimer convenablement les durées de vie de la chaussée, le plus souvent surestimée dans les méthodes de dimensionnement actuelles. Ce travail de doctorat propose une nouvelle approche du contact pneu-chaussée permettant de mieux appréhender les contraintes principales et résiduelles dans une structure de chaussée bitumineuse. A l'aide d'un outil numérique rapide de calcul basé sur une approche semi-analytique (« Semi-Analytical Methods » (SAM)), la géométrie précise du pneumatique est intégrée afin d'obtenir une répartition de pression de contact ainsi qu'un cisaillement surfacique réelle sur la chaussée. Dans un premier temps, un modèle de contact roulant tractif élastique est implémenté pour des cas théoriques simples et validé par des résultats analytiques et numériques de la littérature. Ensuite, ce modèle est étendu pour prendre en compte le comportement élasto-plastique des corps en contact. Ce dernier est comparé à un résultat numérique basé sur la méthode des éléments finis issu de la littérature. Les résultats, pour une application contact pneu-chaussée, montrent une répartition non homogène des contraintes dans la structure et principalement dans les premiers centimètres sous la surface avec des niveaux beaucoup plus importants que peuvent le prédire les modèles actuels qui utilisent une charge uniformément répartie. La pression de contact est comparée aux mesures effectuées par un système nommé TekScan et les champs mécaniques en sous couches sont comparés à ceux d'Alizé-LCPC dans le cas d'une structure simple. Les cisaillements surfaciques sont déterminés dans le cas du roulement tractif. Une application est effectuée sur la modélisation des dégradations des chaussées en surface. Dans un premier temps, des analyses sur le comportement de la chaussée en surface sont effectuées pour une couche de béton bitumineux semi grenu (BBSG) semi-infinie supposée élastique, homogène sous conditions d'accélération, de freinage et de virage. Pour des études sur le top down cracking, des déformations et directions principales sont déterminées et analysées. Ensuite, le modèle de contact élasto-plastique est appliqué sur une couche semi-infinie de grave bitume GB3. Des déformations et contraintes résiduelles générées dans la structure sont déterminées en vue d'une analyse sur les ornières d'instabilité. Une fois validés, ces résultats permettront d'estimer plus fidèlement la durée de vie résiduelle des chaussées mais également de comprendre et d'éviter les mécanismes de dégradation en surface ou proche de la surface. / The recent appearance of new materials in road structures associated with surface layers thickness decreasing and the increasing of trucks loading and their passage frequency has led to new pathologies of degradation. In addition to the well-known rutting problems, top down cracking is now appearing as well as problems of decohesion at the interfaces. These new pathologies led to considerable expenditure on the entire network (around 15 billion euros per year), particularly in urbanized areas that are more prone to surface damage and do not make it possible to adequately estimate the lifetimes of the roadway, most often overestimated in current design methods. This doctoral work proposes a new approach of the tire-road contact allowing for better apprehend of the main and residual stresses in a bituminous pavement structure. Using a fast numerical tool based on a semi-analytical approach ("Semi-Analytical Methods" (SAM)), the precise geometry of the tire is integrated in order to obtain a real contact pressure distribution as well as surface shear on the pavement surface. Initially, an elastic tractive rolling contact model is implemented for simple theoretical cases and validated by analytical and numerical results from the literature.Then, this model is extended to take into account the elastoplastic behavior of the bodies in contact. This is compared to a numerical result based on the nite element method from the literature. The application for tire-pavement contact results, show a non-uniform distribution of stresses in the structure and mainly in the rst centimeters below the surface with much higher levels than can be predicted by current models that use a uniformly distributed load. The contact pressure is compared to the measurements made by a system called TekScan and the mechanical elds in sublayers are compared to those of Alizé-LCPC in the case of a simple structure. The surface shears are determined in the case of tractive rolling. An application is carried out on the modeling of surface pavement damage. Firstly, analyzes of the behavior of the surface pavement are carried out for a semi-innite semi-grit asphalt concrete layer supposed to be elastic, homogeneous under conditions of acceleration, braking and turning. For studies on top down cracking, principals deformations and directions are determined and analyzed. Then, the elastoplastic contact model is applied on a semi-innite asphalt agragate layer. Deformations and residuals stresses generated in the structure are determined for an analysis on the instability ruts. Once validated, these results will make it possible to more accurately estimate the residual life of pavements but also to understand and avoid surface or near surfacedegradation mechanisms.
56

Avaliação de duas técnicas de reciclagem de pavimento flexível in situ com adição de cimento portland para a utilização em camada de base, em um trecho da rodovia Visconde de Porto Seguro/SP

Feitoza, José Costa 29 April 2015 (has links)
Submitted by Kamila Costa (kamilavasconceloscosta@gmail.com) on 2015-07-03T19:40:13Z No. of bitstreams: 2 Dissertação-José C Feitoza.pdf: 2651343 bytes, checksum: 7a35d74605d8cb0399047e68bf28ebaf (MD5) ficha_catalográfica.pdf: 1964 bytes, checksum: 433c944e93f4431471bf2eccf730679e (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-07-13T15:06:21Z (GMT) No. of bitstreams: 2 Dissertação-José C Feitoza.pdf: 2651343 bytes, checksum: 7a35d74605d8cb0399047e68bf28ebaf (MD5) ficha_catalográfica.pdf: 1964 bytes, checksum: 433c944e93f4431471bf2eccf730679e (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-07-13T15:17:35Z (GMT) No. of bitstreams: 2 Dissertação-José C Feitoza.pdf: 2651343 bytes, checksum: 7a35d74605d8cb0399047e68bf28ebaf (MD5) ficha_catalográfica.pdf: 1964 bytes, checksum: 433c944e93f4431471bf2eccf730679e (MD5) / Made available in DSpace on 2015-07-13T15:17:35Z (GMT). No. of bitstreams: 2 Dissertação-José C Feitoza.pdf: 2651343 bytes, checksum: 7a35d74605d8cb0399047e68bf28ebaf (MD5) ficha_catalográfica.pdf: 1964 bytes, checksum: 433c944e93f4431471bf2eccf730679e (MD5) Previous issue date: 2015-04-29 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study evaluated two cold flexible pavement recycling techniques "in situ" with the addition of Portland cement (CP II E 32) for the base layer, through analysis of the laboratory tests results and reviews of experimental sections performed on Highway Visconde Porto Seguro / SP, called SP 332, in the granting of DER-SP. Laboratory tests were conducted to prove the influence of the variability of the aggregates and the effect of Portland cement content in the dosage of recycled cold mixtures using mechanical behavior results as evaluation criteria in order to certify the technical quality of recycling layer base. The design of the passages in the experimental track allowed the determination of the flexible pavement recycling methods in situ with the mobile plant KMA 200 and the Wirtgen 2500S equipment for recycling. The monitoring the implementation, by companies, helped to understand the advantages and limitations the set of equipment employed in both recycling techniques of the experimental lane. The monitoring of experimental sections, during and after the construction process, allowed to verify that the cold recycling solution of flexible pavement for technical study, is beneficial to the structural and functional condition thereof. / Esta pesquisa avaliou duas técnicas de reciclagem a frio de pavimentos flexíveis in situ com adição de cimento Portland (CP II E 32) para camada de base, por meio de análises dos resultados de ensaios laboratoriais e avaliações de trechos experimentais executados na Rodovia Visconde de Porto Seguro/SP, denominada de SP 332, sob a concessão do DER-SP. Os ensaios laboratoriais foram conduzidos a fim de comprovar a influência da variabilidade dos agregados e o efeito do teor de cimento Portland na dosagem de misturas recicladas a frio, utilizando resultados de comportamento mecânico como parâmetros de avaliação para atestar a qualidade técnica da reciclagem da camada de base. A concepção dos trechos na pista experimental permitiu determinar os métodos de reciclagem do pavimento flexível in situ com a usina móvel KMA 200 e com a recicladora Wirtgen 2500 S. O acompanhamento da execução, pelas empresas fomentadoras, contribuiu para compreender as vantagens e limitações do conjunto de equipamentos empregados nas duas técnicas de reciclagem da pista experimental. O monitoramento dos trechos experimentais, durante o processo construtivo e posterior a execução, permitiu verificar que a solução de reciclagem a frio do pavimento flexível para as técnicas em estudo, é benéfica para a condição estrutural e funcional dos mesmos.
57

Stochastic Modelling of Flexible Pavement Performance

Dilip, Deepthi Mary January 2015 (has links) (PDF)
Stochastic analysis provides a rationale for the treatment of uncertainties, founded on the principles of probability theory and statistics, and is concerned with a quantifiable measure of the confidence or the reliability associated with any design process. In this thesis, a stochastic approach is employed in the design of flexible pavement structures, to facilitate the development of safe and reliable pavement structures. The important aspects that have been explored in sufficient detail include the system reliability and global sensitivity analysis, and the spatial and temporal uncertainties that pervade the life of pavements. Chapter 1 of the thesis provides an introduction to the stochastic modelling of flexible pavements and its significance in the present day. Highlighting the need for this study, this chapter also enumerates its objectives and presents an overview of the organization of the thesis. Chapter 2 provides a review of the existing literature of the design of flexible pavements and the approaches adopted to deal with the various sources of uncertainties in a probabilistic setting. The estimation of the uncertainties in fundamental pavement design inputs and their integration into the general performance prediction procedures has become a required component of the modern Mechanistic-Empirical pavement design methodology, which has been described in detail. This chapter also provides the scope of the thesis by identifying the areas of stochastic analysis that have received little attention in the flexible pavement design, which include the effect of spatial variability on the pavement structural responses and the techniques of global sensitivity analysis. Chapter 3 provides a detailed overview of the various methodologies adopted in this thesis to carry out the stochastic modelling of flexible pavements. The fundamental technique adopted for the analysis of reliability is the Monte Carlo Simulation (MCS), which relies upon a numerical/analytical model of the physical system, i.e. the pavement model and a probabilistic description of the design parameters represented by random variables or random fields. The high computational expense associated with the MCS, particularly in the case of random fields, is tackled by the use of meta-models based on the stochastic response surface methodology. The chapter outlines the steps followed to develop the meta-models in the form of Polynomial Chaos Equations (PCEs) and its extension to the Sparse PCE that can conveniently represent the spatial variability of the pavement fields. Chapter 4 deals with the probabilistic modelling of flexible pavements, where the design parameter and model uncertainties are quantified based on the available literature studies. The global sensitivity analysis, which aims to study the impact of the input uncertainty on the variation of a model output (critical pavement responses) through uncertainty propagation, is achieved by the construction of the Polynomial Chaos Equations (PCEs). To implement the global sensitivity analysis in a system reliability framework, a generalized approach based on Bayes’ theorem and the concept of entropy as a sensitivity measure, has been proposed in this chapter. Chapter 5 deals with the characterization of the spatial variability inherent in the pavement layer by employing random fields and analyzing the effect on the pavement responses. The discretization of the random field into a vector of random variables is achieved through the simple Midpoint Discretization and the efficient Expansion Optimal Linear Estimation method. Since the computational effort in stochastic problems is proportional to the number of random variables involved, it is desirable to use a small number of random variables to represent the random field. To achieve this, the principle of transformation of the original random variables into a set of uncorrelated random variables through an eigenvalue orthogonalization procedure is adopted. To further increase the computational efficiency of generating random fields for Monte Carlo Simulation, the variance reduction technique of Latin Hypercube Sampling and the meta-modelling technique using Sparse Polynomial Chaos Equations (SPCEs) are implemented. The primary focus of this chapter is to analyze the influence of the spatial variability of the pavement layer moduli, including its anisotropic characteristics on the pavement structural responses. Chapter 6 focuses on the time-dependent reliability of the pavement structures as they age in service, with due consideration given to degradation of strength with traffic loading. The study is concerned with the fatigue reliability and thereby only the decrease in the asphalt modulus with time is considered as a function of the accumulated damage due to repeated loading, whose uncertainty is determined by the uncertainties of material parameters and the traffic loading. The time-dependent model adopted in this chapter can be quite effortlessly embedded in the Mechanistic-Empirical design framework, and provides a tool to effectively schedule the maintenance of the pavement structure and ensure that the reliability level remains at the desired level for the entire design life of the structure. Chapter 7 summarizes the various studies reported in this thesis and highlights the important conclusions.
58

Análise comparativa de pavimentos dimensionados através dos métodos empírico do DNER e mecanístico e proposta de um catálogo simplificado de pavimentos para a região de Campo Grande (MS) / Comparative analysis of pavements designed by the empirical (DNER) and mechanistic methods and proposal of a simplified catalog of pavements for the area of Campo Grande (MS)

Bezerra Neto, Rogerio Silveira 19 February 2004 (has links)
Este estudo tem como objetivo principal comparar estruturas de pavimentos flexíveis projetadas através dos métodos empírico do DNER e mecanístico, considerando-se alguns materiais de pavimentação utilizados na região de Campo Grande, estado do Mato Grosso do Sul. Como objetivos decorrentes, pode-se destacar a obtenção das características resilientes e de fadiga destes materiais e a proposta de um catálogo simplificado de estruturas de pavimentos para a referida região. Para a efetivação da pesquisa, foram coletados materiais típicos do subleito da região e daqueles mais utilizados na composição de bases e capas dos pavimentos locais. Após as suas caracterizações, realizaram-se ensaios de compactação, CBR, triaxiais cíclicos e compressão diametral estática e dinâmica. As análises mecanísticas foram realizadas utilizando-se o programa computacional FEPAVE, que leva em conta o comportamento elástico não-linear dos materiais, considerando-se o critério de confiabilidade. A partir da análise comparativa dos métodos de dimensionamento, observou-se que, ora as estruturas estabelecidas pelo método mecanístico são idênticas às determinadas pelo método do DNER, ora são mais esbeltas, ora são menos esbeltas, dependendo do tipo de material que constitui as camadas e do nível de confiabilidade adotado. Verificou-se ainda que a caracterização dos materiais através dos ensaios de módulo de resiliência, vida de fadiga e deformação permanente é imprescindível quando se deseja projetar um pavimento empregando-se o método mecanístico. Por fim, elaborou-se um catálogo simplificado de pavimentos flexíveis para a região de Campo Grande – MS, com as intenções de contemplar o uso de materiais locais e auxiliar os engenheiros na concepção de seus projetos / This study has as main objective to compare structures of flexible pavements designed by two different methods, the DNER empirical method and the mechanistic method, being considered some paving materials used in the area of Campo Grande, state of Mato Grosso do Sul. As secondary objectives, it can stand out the obtaining of the mechanical properties of these materials and the proposal of a simplified catalog of flexible pavements for the referred area. For the accomplishment of the research, typical materials of subgrade, base course and surface layer were collected. After their characterizations, tests of compaction, CBR and repeated load were executed. The mechanistic analyses were accomplished being used the software FEPAVE, that takes into account the non-linear resilient modulus of the materials, being considered the reliability criterion. Starting from the comparative analysis of the design methods, it was observed that the structures established by the mechanistic method can be identical, more slender or less slender to the ones obtained by the empirical method, depending on the type of the material that constitutes the layers and the reliability level adopted. It was also verified that the characterization of the materials by repeated load tests (resilient modulus, fatigue’s life and permanent deformation) is indispensable when one want to project a pavement being used the mechanistic method. Finally, a simplified catalog of flexible pavements was elaborated for the area of Campo Grande – MS, with the intentions of to contemplate the use of local materials and to aid the engineers in the conception of their projects
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Análise comparativa de pavimentos dimensionados através dos métodos empírico do DNER e mecanístico e proposta de um catálogo simplificado de pavimentos para a região de Campo Grande (MS) / Comparative analysis of pavements designed by the empirical (DNER) and mechanistic methods and proposal of a simplified catalog of pavements for the area of Campo Grande (MS)

Rogerio Silveira Bezerra Neto 19 February 2004 (has links)
Este estudo tem como objetivo principal comparar estruturas de pavimentos flexíveis projetadas através dos métodos empírico do DNER e mecanístico, considerando-se alguns materiais de pavimentação utilizados na região de Campo Grande, estado do Mato Grosso do Sul. Como objetivos decorrentes, pode-se destacar a obtenção das características resilientes e de fadiga destes materiais e a proposta de um catálogo simplificado de estruturas de pavimentos para a referida região. Para a efetivação da pesquisa, foram coletados materiais típicos do subleito da região e daqueles mais utilizados na composição de bases e capas dos pavimentos locais. Após as suas caracterizações, realizaram-se ensaios de compactação, CBR, triaxiais cíclicos e compressão diametral estática e dinâmica. As análises mecanísticas foram realizadas utilizando-se o programa computacional FEPAVE, que leva em conta o comportamento elástico não-linear dos materiais, considerando-se o critério de confiabilidade. A partir da análise comparativa dos métodos de dimensionamento, observou-se que, ora as estruturas estabelecidas pelo método mecanístico são idênticas às determinadas pelo método do DNER, ora são mais esbeltas, ora são menos esbeltas, dependendo do tipo de material que constitui as camadas e do nível de confiabilidade adotado. Verificou-se ainda que a caracterização dos materiais através dos ensaios de módulo de resiliência, vida de fadiga e deformação permanente é imprescindível quando se deseja projetar um pavimento empregando-se o método mecanístico. Por fim, elaborou-se um catálogo simplificado de pavimentos flexíveis para a região de Campo Grande – MS, com as intenções de contemplar o uso de materiais locais e auxiliar os engenheiros na concepção de seus projetos / This study has as main objective to compare structures of flexible pavements designed by two different methods, the DNER empirical method and the mechanistic method, being considered some paving materials used in the area of Campo Grande, state of Mato Grosso do Sul. As secondary objectives, it can stand out the obtaining of the mechanical properties of these materials and the proposal of a simplified catalog of flexible pavements for the referred area. For the accomplishment of the research, typical materials of subgrade, base course and surface layer were collected. After their characterizations, tests of compaction, CBR and repeated load were executed. The mechanistic analyses were accomplished being used the software FEPAVE, that takes into account the non-linear resilient modulus of the materials, being considered the reliability criterion. Starting from the comparative analysis of the design methods, it was observed that the structures established by the mechanistic method can be identical, more slender or less slender to the ones obtained by the empirical method, depending on the type of the material that constitutes the layers and the reliability level adopted. It was also verified that the characterization of the materials by repeated load tests (resilient modulus, fatigue’s life and permanent deformation) is indispensable when one want to project a pavement being used the mechanistic method. Finally, a simplified catalog of flexible pavements was elaborated for the area of Campo Grande – MS, with the intentions of to contemplate the use of local materials and to aid the engineers in the conception of their projects
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Vliv použití R - materiálu na funkční vlastnosti asfaltových směsí / Influence of usage of recycled material on asphalt mixtures functional properties

Šperka, Pavel January 2015 (has links)
Diploma thesis deals with the topic of using recycled material in the production of asphalt mixtures. In the theoretical part the methods of recycling flexible pavement are described and as well as ways in which recycled material is added to asphalt mixtures produced by the stationary hot mix plant. The thesis also deals with the current state of recycled material use in the Czech Republic and the reasons for its possible greater use. The practical part of the thesis studies the effect of using the amount of 20% recycled material to asphalt mixtures of asphalt concrete for wearing course ACO11+, on selected functional properties of these mixtures. It is also investigates the influence of bitumen binder contained in the recycled material, on the final properties in manufactured asphalt mixtures. An integral part of this thesis is a description of all methods that were used during the processing of the practical part. In the end of this thesis there are some results of findings about adding recycled material into asphalt mixtures.

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