The modeling of Sand Asphalt and experiments to measure their rheological properties are of vital concern to many industrial processes especially highway and roadway pavement construction industry. A variety of hot mix asphalt mixtures are used in highway and runway pavement construction, with each mixture catering to a specific need. These mixtures vary in type and percentage of aggregates and asphalt used and consequently exhibit marked differences in their response. The main thrust of this research is to provide experimental data which would be helpful in determining the efficacy of the constitutive models that have been developed for these hot mix asphalt mixtures. Here we attempt to provide experimental data in the raw form for Sand Asphalt mixtures that would be helpful in the theoretical modeling efforts involving asphalt materials using a continuum point of view. For example the data obtained can be of immense help to evaluate the constitutive model developed by Murali Krishnan and Rajagopal. The Sand Asphalt mixture in their model is modeled as `homogenized' single constituent due to the peculiarity of its makeup. The constitutive model of Murali Krishnan and Rajagopal is based on a thermodynamical framework for materials possessing multiple natural configurations (multiple stress free states) to derive the constitutive equations. Recently an Orthogonal Rheometer was built to characterize the granular solids by Gupta and Rajagopal which was later used by Baek in the torsional mode. In this work we have used the same Torsional Rheometer with some minor modifications in the design to measure some general properties of Sand Asphalt mixtures. Sand Asphalt mixtures, due to their non-linear viscoelastic character, exhibit `normal stress effects' and `stress relaxation'. The Rheometer that we used was able to capture these responses with high precision. We have laid out proper procedures for the further testing of asphalt related mixtures. A typical sand asphalt mixture sample in cylindrical shape was used as the test specimen. From this work some interesting data was obtained. A remarkable observation was that as the shear rate is increased, the normal force and torque generated initially decrease, but beyond a certain shear rate they attain a constant value.

Rutting is one of the major distresses in asphalt pavements and it increases road roughness and traps water, which leads to wet-weather accidents due to the loss of tire-pavement friction and hydroplaning. The fundamental mechanisms of rutting have not been well addressed because of the complexity of asphalt mixtures. A comprehensive characterization of the asphalt mixtures in compression was accomplished by mechanistically modeling the inherent anisotropy, viscoelasticity, viscoplasticity and viscofracture of the material. The inherent anisotropy due to preferentially oriented aggregates was characterized by a microstructural parameter (i.e., modified vector magnitudes) which could be rapidly and accurately measured by lateral surface scanning tests and physically related to anisotropic modulus ratio. The anisotropic viscoelasticity was represented by complex moduli and Poisson's ratios in separate orthogonal directions that were determined by an efficient testing protocol. Master curve models were proposed for the magnitude and phase angle of these complex variables. The viscoplasticity were intensively modeled by an anisotropic viscoplastic model which incorporated 1) modified effective stresses to account for the inherent and stress-induced anisotropy; 2) a new model to provide a smooth and convex yield surface and address the material cohesion and internal friction; 3) a non-associated flow rule to consider the volumetric dilation; and 4) a temperature and strain rate dependent strain hardening function. The viscofracture resulting from the crack growth in compression led to the stress-induced anisotropy and was characterized by anisotropic damage densities, the evolution of which was modeled by the anisotropic pseudo J-integral Paris' laws. Results indicated that the undamaged asphalt mixtures were inherently anisotropic and had vertical to horizontal modulus ratios from 1.2 to 2.0 corresponding to the modified vector magnitudes from 0.2 and 0.5. The rutting would be underestimated without including the inherent anisotropy in the constitutive modeling. Viscoelastic and viscoplastic deformation developed simultaneously while the viscofracture deformation occurred only during the tertiary flow, which was signaled by the increase of phase angle. Axial and radial strain decomposition methods were proposed to efficiently separate the viscoplasticity and viscofracture from the viscoelasticity. Rutting was accelerated by the occurrence of cracks in tertiary flow. The asphalt mixture had a brittle (splitting cracks) or ductile (diagonal cracks) fracture when the air void content was 4% and 7%, respecitvely. The testing protocol that produced the material properties is efficient and can be completed in one day with simple and affordable testing equipment. The developed constitutive models can be effectively implemented for the prediction of the rutting in asphalt pavements under varieties of traffic, structural, and environmental conditions.

The modeling of Sand Asphalt and experiments to measure their rheological properties are of vital concern to many industrial processes especially highway and roadway pavement construction industry. A variety of hot mix asphalt mixtures are used in highway and runway pavement construction, with each mixture catering to a specific need. These mixtures vary in type and percentage of aggregates and asphalt used and consequently exhibit marked differences in their response. The main thrust of this research is to provide experimental data which would be helpful in determining the efficacy of the constitutive models that have been developed for these hot mix asphalt mixtures. Here we attempt to provide experimental data in the raw form for Sand Asphalt mixtures that would be helpful in the theoretical modeling efforts involving asphalt materials using a continuum point of view. For example the data obtained can be of immense help to evaluate the constitutive model developed by Murali Krishnan and Rajagopal. The Sand Asphalt mixture in their model is modeled as `homogenized' single constituent due to the peculiarity of its makeup. The constitutive model of Murali Krishnan and Rajagopal is based on a thermodynamical framework for materials possessing multiple natural configurations (multiple stress free states) to derive the constitutive equations. Recently an Orthogonal Rheometer was built to characterize the granular solids by Gupta and Rajagopal which was later used by Baek in the torsional mode. In this work we have used the same Torsional Rheometer with some minor modifications in the design to measure some general properties of Sand Asphalt mixtures. Sand Asphalt mixtures, due to their non-linear viscoelastic character, exhibit `normal stress effects' and `stress relaxation'. The Rheometer that we used was able to capture these responses with high precision. We have laid out proper procedures for the further testing of asphalt related mixtures. A typical sand asphalt mixture sample in cylindrical shape was used as the test specimen. From this work some interesting data was obtained. A remarkable observation was that as the shear rate is increased, the normal force and torque generated initially decrease, but beyond a certain shear rate they attain a constant value.

This thesis investigates and documents fundamental studies of highway materials (asphalt engineering properties) especially on different modified asphalt binders and mixtures in order to understand failure mechanisms at low temperature and superior performance of such asphalt binders with the aim of preventing premature cracking on Ontario highways. In addition, seven asphalt binders of different compositions were used as a template for study and this research work is tailored towards Superpave® performance-based specification testing with the aim of improving asphalt pavement performance under various conditions and consequently reducing premature cracking in order to achieve long lasting highways. Based on the actual applied pattern of Superpave® specification criteria, the mechanical responses of the binders are analyzed by extended bending beam rheometer (eBBR), tensile stress ductilometer (Petrotest DDA3®), compact tension test (Instron AsphaltPro®), double-edge-notched tension and single-edge-notched tension (MTS 810 universal testing machine) protocols. The objective of this study entails establishing and developing of a proper procedure for the testing of binders with the aim of ranking (grading) the performance after validation of laboratory and field experiments. Analysis of the results appears to show that the premature distress on the Highway 417 trial sections can be attributed to reversible aging tendency (wax crystallization) at low temperatures coupled with low fatigue resistance of the binders. The results suggest that different polymer modifications had significant influence on the performance of asphalt mix as demonstrated from the results obtained from essential and plastic work of fracture using double-edge-notch-tension test (DENT). Crack tip opening displacement (CTOD) parameter consistently show the performing grading of asphalt binder while compact tension test protocol provides plane strain fracture toughness (K1c) which could be used to rank binders with respect to fracture resistance at low temperature. Hence, CTOD is a promising parameter which can be used to establish performance ranking of the binders. / Thesis (Master, Chemistry) -- Queen's University, 2008-05-26 09:54:23.308

The fatigue damage is one of the most common distresses observed on the asphalt concrete pavement. The initiation and propagation of the fatigue damage is a complicated phenomenon and very difficult to detect. In order to thoroughly understand the fatigue of asphalt concrete, the behaviors of the key components of asphalt concrete under cyclic loading are investigated respectively. A new experiment method is developed to test the performances of asphalt binder, mastic and mixture under cyclic loading, which provides a tool to unify the fatigue test method for both binding medium and asphalt mixture. Using the new fatigue test method, the effects of loading magnitude, temperature and loading rate to the performance of the asphalt binder under cyclic loading are estimated. Mastic and mixture specimens are prepared by adding fillers and controlled-size aggregates into the asphalt binder. The effects of filler content to the performance of mastic specimen are discussed. The differences between the test results of mastic and mixture are compared and analyzed. Incorporated with the new fatigue test, x-ray tomography system is used in this study to: 1. Analyze the structure change of the mastic specimen before and after the fatigue test. 2. Compare the void content differences between the mastic and mixture specimens. 3. Reconstruct the 3-D internal structures of mastic and mixture specimens to build up the digital specimens. The digital specimens are used in the fatigue simulation of the asphalt binder, mastic and mixture specimens based on the finite element method. The asphalt binder, filler and aggregate are treated as different materials. Damage parameter is introduced to model the degradation of elastic modulus of the asphalt binder caused by fatigue damage. Direct cyclic analysis available in ABAQUS is used to obtain the response of the material after large number of loading cycles. The basalt fibers are dispersed into the asphalt binder and mastic specimens, the effects of the basalt fiber to the performances of the binder and mastic at low temperature are analyzed using both experimental and FEM modeling methods. / Ph. D.

Development of new asphalt technologies to reduce both energy consumption and CO2 production has attracted great interest in recent years. The use of foam bitumen, as one of them, is attractive due to the low investment and production cost. Formation and decay of foam bitumen is a highly dynamic temperature dependent process which makes characterization difficult. In this thesis, new experimental tools were developed and applied for characterizing the foam bitumen during the hot foaming process.  One of the main goals of this study was to improve understanding and characterization of the foam bitumen formation and decay. X-ray radiography was used to study the formation and decay of foam bitumen in 2D representation. The results demonstrate that the morphology of bubble formation depends on the types of bitumen used. Moreover, theoretical investigation based on the 3D X-ray computed tomography scan dataset of bubble merging showed that the disjoining pressure increased as the gap between the bubbles in the surface layer (foam film) decreased with time and finally was ruptured.   Examining the foam bitumen stream right at the nozzle revealed that foam bitumen at a very early stage contains fragmented pieces of irregular size rather resembling a liquid than foam. The result from thermogravimetric analysis demonstrated that residual water content depends on the initial water content, and was found to be between 38 wt% and 48 wt% of the initial water content of 4 wt% to 6 wt%. Moreover the influence of viscosity and surface tension on bubble shape and rise velocity of the bubbles using level-set method was implemented in finite element method. The modeling results were compared with bubble shape correlation map from literature. The results indicated that the bubble shapes are more dependent on the surface tension parameters than to the viscosity of the bitumen, whereas the bitumen viscosity is dominant for bubble rising velocity. / <p>QC 20160303</p>

A caracterização das propriedades visco-elástico-plásticas dos materiais asfálticos são importantes para uma melhor compreensão do comportamento mecânico e performance de pavimentos. O módulo complexo visa caracterizar as propriedades viscoelásticas lineares do material presente no campo das pequenas deformações. O ensaio para obtenção do módulo dinâmico pode ser realizado a partir de um carregamento senoidal uniaxial de compressão com frequências que podem variar de 0,1Hz a 25Hz e com temperaturas de -10°C a 54°C. O valor absoluto do módulo complexo é conhecido como módulo dinâmico |E*|, que pode ser definido como uma relação entre a amplitude de tensão e a amplitude de deformação. Já, a defasagem entre a tensão e a deformação é conhecida como ângulo de fase, que é um indicador das propriedades viscosas do material. Esta dissertação possuiu como objetivo caracterizar as propriedades viscoelásticas das misturas asfálticas quentes e mornas comumente utilizadas no Rio Grande do Sul, utilizando um aditivo surfactante para as misturas mornas. Para tanto foram dosadas 4 misturas asfálticas com agregados basálticos e os ligantes CAP 50/70, AMP 60/85, AB8 e CAP TLA e obtidos os parâmetros de adesividade e resistência dessas misturas quentes e mornas. Para a realização do ensaio de módulo dinâmico foi realizado uma revisão bibliográfica sobre os procedimentos de ensaio e análise de dados, posteriormente, foi adotada a metodologia adequada para os ensaios. Os mesmos foram realizados utilizando uma prensa universal MTS e a análise dos dados foi realizada com o auxílio das ferramentas do Microsoft Excel. Através do estudo foi possível concluir que as misturas com ligante convencional possuem um comportamento similar entre a mistura convencional e a morna. O mesmo não ocorre nas misturas com ligante modificado, onde ocorre uma alteração tanto da fase viscosa como da elástica, sendo esse efeito mais predominante nas misturas modificadas por polímero. / The characterization of the viscoelastic-plastic properties of asphaltic materials are important for a better understanding of the pavements’ mechanical behavior and performance. The complex module aims to characterize as linear viscoelastic properties of the material present in the field of small deformations. The assay for obtaining the dynamic modulus can be performed from a compression uniaxial sinusoidal loading with frequencies ranging from 0.1Hz to 25Hz and temperatures from -10 °C to 54 °C. The absolute value of the complex modulus is known as dynamic module | E * |, which is defined as a relation between a stress amplitude and a strain amplitude. Already, a discrepancy between stress and strain is known as phase angle, which is an indicator of the viscous properties of the material. This dissertation aimed to characterize as viscoelastic properties of hot and warm asphalt mixtures commonly used in Rio Grande do Sul, using a surfactant additive for warm mixtures. In order to do so, four asphalt concrete mixes - composed with the basalt aggregates and binders CAP 50/70, AMP 60/85, AB 8 and CAP TLA – were designed. In addition, the parameters of adhesiveness and resistance to hot and warm mixtures were obtained. For a dynamic modulus test, a literature review was performed about the data analysis and test procedure, and a suitable methodology for testing was subsequently adopted. The tests were realized with an universal testing machine of MTS and the data analysis were performed by means of the Microsoft Excel tools. Through the study it was possible to conclude that mixtures with conventional binder presented similar behavior between a conventional and a warm mixture. The same does not occur in mixtures with modified binder, where a change in both the viscous and the elastic phases occurs, and this effect is more predominant in the polymer modified mixtures.

A presente pesquisa apresenta uma análise laboratorial da adesividade e do comportamento mecânico de concretos asfálticos elaborados com agregados de granito e com ligante convencional (CAP 50/70) e ligante modificado por polímero (AMP CAP 60/85), priorizando os efeitos decorrentes da incorporação de dois tipos de cales. A primeira, denominada cal calcítica (com elevado teor de óxido de cálcio) é oriunda do Estado de Minas Gerais e, a segunda, denominada cal dolomítica, produzida no Estado do Rio Grande do Sul. Para a dosagem das seis misturas estudadas foi utilizada a metodologia Marshall, sendo posteriormente realizados ensaios de Resistência à Tração por Compressão Diametral, Módulo de Resiliência, Dano por Umidade Induzida (AASHTO T 283/89) e Resistência à Fadiga utilizando-se o ensaio de Tração indireta por compressão diametral, no modo tensão controlada. De posse dos resultados laboratoriais foi realizada uma análise elástico - linear, utilizando o Programa Computacional EVERSTRESS 5.0, e aplicado os resultados de deformação nos modelos obtidos em laboratório para as seis misturas analisadas. Considerando este critério, pode-se observar que os melhores resultados foram obtidos para as misturas elaboradas com ligante modificado. Quando empregado o ligante convencional evidenciou-se a melhora do comportamento da resistência à Fadiga das misturas que tiveram incorporação de cal (aumento de até 330% quando empregada cal calcítica e de até 348% quando empregada cal dolomítica), enquanto que quando preparadas com ligante modificado por polímero, a mistura que apresentou melhores resultados foi a elaborada sem incorporação de cal. Outro fato constatado e importante diz respeito a interação entre a cal, o ligante e o agregado granítico, já que diferentemente do esperado, a incorporação de cales não ocasionou resultados satisfatórios na adesividade. / This research shows a laboratory test of adhesiveness and the mechanical behavior of asphalt concrete prepared with granitic aggregate and conventional binder (CAP 50/70) and polymer-modified binder (AMP CAP 60/85), prioritizing the effects resulting from the merger of two types of limes. The first, called calcite lime (with high content of calcium oxide), comes from the Brazilian State of Minas Gerais; the second, the dolomitic lime, is produced in the State of Rio Grande do Sul. The Marshall method assessed the six mixtures studied; subsequently, Tensile Strength for Diametral Compression, Resilience Module, Damage Induced by Humidity (AASHTO T 283/89) and Resistance to Fatigue were tested by means of indirect traction by diametrical compression in controlled stress mode. A linear elastic analysis followed the laboratory results, using Computational Program EVERSTRESS 5.0; deformation results obtained in laboratory models for the six analyzed mixtures were applied. In accordance with this criterion, the best results point to asphalt mixtures prepared with modified binder. The use of conventional binder showed improvement in the fatigue resistance behavior of mixtures that take lime incorporation (increase of up to 330% with calcite lime, and up to 348% with dolomitic lime); however, when prepared with polymer-modified binder, the mixture that showed the best results did not have the addition of lime. Another noteworthy fact confirmed concerns the interaction amongst the lime, the binder and the granitic aggregate: unlike expected, the incorporation of limes did not convey satisfactory results in adhesiveness.

A presente pesquisa apresenta uma análise laboratorial da adesividade e do comportamento mecânico de concretos asfálticos elaborados com agregados de granito e com ligante convencional (CAP 50/70) e ligante modificado por polímero (AMP CAP 60/85), priorizando os efeitos decorrentes da incorporação de dois tipos de cales. A primeira, denominada cal calcítica (com elevado teor de óxido de cálcio) é oriunda do Estado de Minas Gerais e, a segunda, denominada cal dolomítica, produzida no Estado do Rio Grande do Sul. Para a dosagem das seis misturas estudadas foi utilizada a metodologia Marshall, sendo posteriormente realizados ensaios de Resistência à Tração por Compressão Diametral, Módulo de Resiliência, Dano por Umidade Induzida (AASHTO T 283/89) e Resistência à Fadiga utilizando-se o ensaio de Tração indireta por compressão diametral, no modo tensão controlada. De posse dos resultados laboratoriais foi realizada uma análise elástico - linear, utilizando o Programa Computacional EVERSTRESS 5.0, e aplicado os resultados de deformação nos modelos obtidos em laboratório para as seis misturas analisadas. Considerando este critério, pode-se observar que os melhores resultados foram obtidos para as misturas elaboradas com ligante modificado. Quando empregado o ligante convencional evidenciou-se a melhora do comportamento da resistência à Fadiga das misturas que tiveram incorporação de cal (aumento de até 330% quando empregada cal calcítica e de até 348% quando empregada cal dolomítica), enquanto que quando preparadas com ligante modificado por polímero, a mistura que apresentou melhores resultados foi a elaborada sem incorporação de cal. Outro fato constatado e importante diz respeito a interação entre a cal, o ligante e o agregado granítico, já que diferentemente do esperado, a incorporação de cales não ocasionou resultados satisfatórios na adesividade. / This research shows a laboratory test of adhesiveness and the mechanical behavior of asphalt concrete prepared with granitic aggregate and conventional binder (CAP 50/70) and polymer-modified binder (AMP CAP 60/85), prioritizing the effects resulting from the merger of two types of limes. The first, called calcite lime (with high content of calcium oxide), comes from the Brazilian State of Minas Gerais; the second, the dolomitic lime, is produced in the State of Rio Grande do Sul. The Marshall method assessed the six mixtures studied; subsequently, Tensile Strength for Diametral Compression, Resilience Module, Damage Induced by Humidity (AASHTO T 283/89) and Resistance to Fatigue were tested by means of indirect traction by diametrical compression in controlled stress mode. A linear elastic analysis followed the laboratory results, using Computational Program EVERSTRESS 5.0; deformation results obtained in laboratory models for the six analyzed mixtures were applied. In accordance with this criterion, the best results point to asphalt mixtures prepared with modified binder. The use of conventional binder showed improvement in the fatigue resistance behavior of mixtures that take lime incorporation (increase of up to 330% with calcite lime, and up to 348% with dolomitic lime); however, when prepared with polymer-modified binder, the mixture that showed the best results did not have the addition of lime. Another noteworthy fact confirmed concerns the interaction amongst the lime, the binder and the granitic aggregate: unlike expected, the incorporation of limes did not convey satisfactory results in adhesiveness.

A caracterização das propriedades visco-elástico-plásticas dos materiais asfálticos são importantes para uma melhor compreensão do comportamento mecânico e performance de pavimentos. O módulo complexo visa caracterizar as propriedades viscoelásticas lineares do material presente no campo das pequenas deformações. O ensaio para obtenção do módulo dinâmico pode ser realizado a partir de um carregamento senoidal uniaxial de compressão com frequências que podem variar de 0,1Hz a 25Hz e com temperaturas de -10°C a 54°C. O valor absoluto do módulo complexo é conhecido como módulo dinâmico |E*|, que pode ser definido como uma relação entre a amplitude de tensão e a amplitude de deformação. Já, a defasagem entre a tensão e a deformação é conhecida como ângulo de fase, que é um indicador das propriedades viscosas do material. Esta dissertação possuiu como objetivo caracterizar as propriedades viscoelásticas das misturas asfálticas quentes e mornas comumente utilizadas no Rio Grande do Sul, utilizando um aditivo surfactante para as misturas mornas. Para tanto foram dosadas 4 misturas asfálticas com agregados basálticos e os ligantes CAP 50/70, AMP 60/85, AB8 e CAP TLA e obtidos os parâmetros de adesividade e resistência dessas misturas quentes e mornas. Para a realização do ensaio de módulo dinâmico foi realizado uma revisão bibliográfica sobre os procedimentos de ensaio e análise de dados, posteriormente, foi adotada a metodologia adequada para os ensaios. Os mesmos foram realizados utilizando uma prensa universal MTS e a análise dos dados foi realizada com o auxílio das ferramentas do Microsoft Excel. Através do estudo foi possível concluir que as misturas com ligante convencional possuem um comportamento similar entre a mistura convencional e a morna. O mesmo não ocorre nas misturas com ligante modificado, onde ocorre uma alteração tanto da fase viscosa como da elástica, sendo esse efeito mais predominante nas misturas modificadas por polímero. / The characterization of the viscoelastic-plastic properties of asphaltic materials are important for a better understanding of the pavements’ mechanical behavior and performance. The complex module aims to characterize as linear viscoelastic properties of the material present in the field of small deformations. The assay for obtaining the dynamic modulus can be performed from a compression uniaxial sinusoidal loading with frequencies ranging from 0.1Hz to 25Hz and temperatures from -10 °C to 54 °C. The absolute value of the complex modulus is known as dynamic module | E * |, which is defined as a relation between a stress amplitude and a strain amplitude. Already, a discrepancy between stress and strain is known as phase angle, which is an indicator of the viscous properties of the material. This dissertation aimed to characterize as viscoelastic properties of hot and warm asphalt mixtures commonly used in Rio Grande do Sul, using a surfactant additive for warm mixtures. In order to do so, four asphalt concrete mixes - composed with the basalt aggregates and binders CAP 50/70, AMP 60/85, AB 8 and CAP TLA – were designed. In addition, the parameters of adhesiveness and resistance to hot and warm mixtures were obtained. For a dynamic modulus test, a literature review was performed about the data analysis and test procedure, and a suitable methodology for testing was subsequently adopted. The tests were realized with an universal testing machine of MTS and the data analysis were performed by means of the Microsoft Excel tools. Through the study it was possible to conclude that mixtures with conventional binder presented similar behavior between a conventional and a warm mixture. The same does not occur in mixtures with modified binder, where a change in both the viscous and the elastic phases occurs, and this effect is more predominant in the polymer modified mixtures.