Hot-mix asphalt concrete (HMAC) mixture fatigue characterization constitutes a fundamental component of HMAC pavement structural design and analysis to ensure adequate field fatigue performance. HMAC is a heterogeneous complex composite material of air, binder, and aggregate that behaves in a non-linear elasto-viscoplastic manner, exhibits anisotropic behavior, ages with time, and heals during traffic loading rest periods and changing environmental conditions. Comprehensive HMAC mixture fatigue analysis approaches that take into account this complex nature of HMAC are thus needed to ensure adequate field fatigue performance. In this study, four fatigue analysis approaches; the mechanistic empirical (ME), the calibrated mechanistic with (CMSE) and without (CM) surface energy measurements, and the proposed NCHRP 1-37A 2002 Pavement Design Guide (MEPDG) were comparatively evaluated and utilized to characterize the fatigue resistance of two Texas HMAC mixtures in the laboratory, including investigating the effects of binder oxidative aging. Although the results were comparable, the CMSE/CM approaches exhibited greater flexibility and potential to discretely account for most of the fundamental material properties (including fracture, aging, healing, visco-elasticity, and anisotropy) that affect HMAC pavement fatigue performance. Compared to the other approaches, which are mechanistic-empirically based, the CMSE/CM approaches are based on the fundamental concepts of continuum micromechanics and energy theory.

Fatigue cracking is one of the most common distresses of asphalt pavements, whereas healing is a counter process to cracking which alleviates cracking damage and extends fatigue life of asphalt pavements. Most of existing methods to characterize fatigue cracking and healing are generally empirical or phenomenological in nature, which does not satisfy the need to develop mechanistic-based pavement design methods. The objective of this study is to characterize fatigue cracking and healing of asphalt mixtures using an energy-based mechanistic approach. A controlled-strain repeated direct tension (RDT) test is selected to generate both fatigue cracking and permanent deformation in an asphalt mixture specimen. Fatigue cracking is separated from permanent deformation from a mechanical viewpoint. The development of fatigue cracking is described by the evolution of the damage density and the increase of the average crack size with the increase of loading cycles. A creep and step-loading recovery (CSR) test is designed to measure the internal stress in the recovery phase of an asphalt mixture specimen. The internal stress and the strain measured in the recovery phase are used to conduct the mechanistic analysis of recovery and healing of the asphalt mixture specimen. Then healing is described using the decrease of the damage density and average crack size with time. Different types of asphalt mixtures produce distinctly different fatigue cracking and healing characteristics. The effect of mixture composition, temperature, and aging are evaluated using the approach above. The entire series of tests for fatigue, permanent deformation and healing can be completed in one day, with the healing part requiring only a matter of minutes. The methods proposed in this study characterize fatigue cracking and healing of asphalt mixtures using its essential cause and effect relationship.

Hot-mix asphalt concrete (HMAC) mixture fatigue characterization constitutes a fundamental component of HMAC pavement structural design and analysis to ensure adequate field fatigue performance. HMAC is a heterogeneous complex composite material of air, binder, and aggregate that behaves in a non-linear elasto-viscoplastic manner, exhibits anisotropic behavior, ages with time, and heals during traffic loading rest periods and changing environmental conditions. Comprehensive HMAC mixture fatigue analysis approaches that take into account this complex nature of HMAC are thus needed to ensure adequate field fatigue performance. In this study, four fatigue analysis approaches; the mechanistic empirical (ME), the calibrated mechanistic with (CMSE) and without (CM) surface energy measurements, and the proposed NCHRP 1-37A 2002 Pavement Design Guide (MEPDG) were comparatively evaluated and utilized to characterize the fatigue resistance of two Texas HMAC mixtures in the laboratory, including investigating the effects of binder oxidative aging. Although the results were comparable, the CMSE/CM approaches exhibited greater flexibility and potential to discretely account for most of the fundamental material properties (including fracture, aging, healing, visco-elasticity, and anisotropy) that affect HMAC pavement fatigue performance. Compared to the other approaches, which are mechanistic-empirically based, the CMSE/CM approaches are based on the fundamental concepts of continuum micromechanics and energy theory.

Este trabalho teve como objetivo principal investigar, do ponto de vista volumétrico, qual seria o número de giros necessário, no Compactador Giratório Superpave (CGS), para produzir corpos de prova com características similares aos produzidos com a energia 50 golpes no compactador Marshall, para misturas tipo Stone Matrix Asphalt (SMA) com volume de vazios igual a 4%. Como complemento, realizaram-se dosagens no CGS com 100 giros, visando avaliar o impacto do aumento da energia de compactação no teor de projeto, também para volume de vazios igual a 4%, em comparação aos CPs compactados com o número de giros equivalente à Marshall determinada anteriormente. Foram utilizadas duas faixas granulométricas de misturas SMA: a com Tamanho Máximo Nominal (TMN) 7,93 mm do DER-SP e a com TMN 12,5 mm da AASHTO. Para todas as misturas foram avaliadas as propriedades mecânicas de corpos de prova com 4% de volume de vazios. Dos resultados dos ensaios concluiu-se que o número de giros no CGS para produzir misturas com volume de vazios igual a 4% nos teores de asfalto de trabalho Marshall são similares para as duas faixas granulométricas utilizadas. Por outro lado, a dosagem com 100 giros no CGS reduziu significativamente o teor de asfalto de trabalho para as duas faixas estudadas em comparação com os teores de trabalho obtidos das dosagens Marshall e no CGS com os números de giros equivalentes. Com relação às propriedades mecânicas, as resistências à tração e os módulos de resiliência dos corpos de prova produzidos com 100 giros no CGS são, de uma maneira geral, um pouco menores que os valores obtidos nos corpos de prova compactados no compactador Marshall, independente da faixa granulométrica, porém maiores que os valores obtidos para a compactação giratória nas energias equivalentes. A vida de fadiga para a faixa mais fina é significativamente maior para os corpos de prova compactados com 100 giros em comparação com a compactação Marshall e para a faixa mais grossa manteve-se na mesma ordem de grandeza da obtida para a compactação Marshall. Para as misturas ensaiadas, não foi constatado influência da compactação no dano causado pela umidade induzida / The aim of the work was to investigate, in terms of volumes properties, which would be the number of gyrations required in the Superpave Gyrations Compactor (SGC), to produce samples with characteristics similar to the energy produced with 50 blows in the Marshall Compactor, for Stone Matrix Asphalt (SMA) mixtures with voids content equal to 4%. As a complement, samples designed in the SGC with 100 gyrations, were made to evaluate the impact of increased compaction energy in the binder content, also for voids content equal to 4%, compared to the samples compacted with a number of gyrations equivalent to Marshall, as previously determined. It was used two different aggregates gradations for SMA mixtures: Nominal Maximum Size (NMS) 7,93 mm of the DER and the NMS 12,5 mm of the AASHTO. The mechanical properties of all samples were evaluated with voids content of 4%. The number of gyrations in the SGC to produce mixtures containing voids content equal to 4% for the Marshall`s binder content are similar for both aggregates gradations used. On the other hand, the SMA mixture design with 100 gyrations reduced the binder content for both gradations in comparison with the binder content obtained from Marshall Compaction and SGC with the equivalent number of gyrations. Concerning mechanical properties, the tensile strength and resilient modulus of the samples produced with 100 gyrations in the SGC are, generally, slightly lower than the values obtained with the samples compacted in the Marshall compactor, independent of the aggregate gradations, but higher than the values obtained with the samples compacted with a equivalent energy in the SGC. The fatigue life for the fine gradation (NMS=7,93mm) is significantly higher for the samples compacted in the SGC with 100 gyrations compared with the Marshall compaction, and for the coarse gradation (NMS=12,5 mm) remained in the same order of magnitude that of the Marshall compaction. It was not observed any influence of the compaction method in the induced damage caused by moisture

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No. of bitstreams: 1 Dissertação-Diego Meneses de Melo.pdf: 12978397 bytes, checksum: b2f17a79227222cd6931f419830d812b (MD5) Previous issue date: 2010-07-22 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The dissertation now presented has the objective to accomplish a study about the use of constructions and demolitions waste (CDW) as coarse aggregate in asphalt concrete, searching for environmental and technical solution to the historical stony aggregate lack in the city of Manaus-AM. The research displays peculiar characteristics of the alternative material, comparing with the pebble, usual element in the asphalt mixtures regionally used. It was conducted the dosage of a mixture with pebble and another one with CDW, fulfilling the function of coarse aggregates, keeping the other elements: CAP 50/70 as binder, residual sand as fine aggregate, Portland cement as filler. The gradation definition was made by the Bailey Method, enabling the obtainment of a structural skeleton that privileged the grains interlocking, allowing a study of the form and superficial texture influence in the mixture mechanical behavior. As performance markers was made tests of Tensile Strength (TS), Loss of Resistance by Induced Moisture (Lottman Test), Resilient Modulus (RM), Fluency for Axial Compression (creep), by static and dynamic method. Temperature was varied in all assays, excepted for the Lottman, objecting to investigate the sensitivity of the mixtures to this factor. All the procedures had its results considered as for the resistance and deformability. The viability of the use of the CDW as aggregate in asphalt concrete was evidenced, in substitution to the pebble, because the alternative material revealed, for the most part of the tests, more stability under temperatures higher than 25°C. Its tensile strength was higher than of the pebble, independently of the temperature or the load speed. The Resilient Modulus and the deformation accumulated in the fluency tests demonstrated that, for the typical service temperatures of Manaus (around 40°C), the alternative mixture has better performance than one with natural material. However, CDW showed more susceptibility for the moisture action. It was concluded, based on the results, which the irregular form and the rugous superficial texture of the residue aggregate were responsible for an increase in the friction between particles in the structural skeleton of the mixture collaborating with the shear strength, especially for the highest temperatures of operation, when the viscous phase introduce great influence in the mechanical behavior. / A dissertação ora apresentada tem por objetivo realizar estudo sobre a utilização de resíduos de construções e demolições (RCD) como agregado graúdo em concreto asfáltico, buscando solução técnica e ambiental para a carência histórica de agregados pétreos no município de Manaus-AM. A pesquisa expõe características peculiares do material alternativo, comparando com o seixo rolado, elemento usual nas misturas asfálticas utilizadas regionalmente. Realizouse a dosagem de uma mistura com seixo e outra com RCD, cumprindo a função de agregado graúdo, mantendo os demais partícipes constantes: CAP 50/70 como ligante, areia residual como agregado miúdo, cimento Portland como material de enchimento. A definição da granulometria foi feita por meio do Método de Bailey, possibilitando definir um esqueleto estrutural que privilegiasse o intertravamento dos grãos, de modo a estudar a influência da forma e textura superficial no comportamento mecânico da mistura. Como balizadores do desempenho foram realizados ensaios de Resistência à Tração (RT), Perda de Resistência por Umidade Induzida (Ensaio Lottman), Módulo de Resiliência (MR), Fluência por Compressão Axial (creep) estático e dinâmico. Variou-se a temperatura em todos os ensaios, a exceção do Lottman, de modo a investigar a sensibilidade das misturas a este fator. Todos os procedimentos tiveram seus resultados julgados quanto à resistência e deformabilidade. Foi constatada a viabilidade do uso do RCD em concreto asfáltico, em substituição ao seixo, uma vez que o material alternativo mostrou-se, na maior parte dos ensaios, mais estável sob temperaturas maiores que 25°C. Sua resistência à tração foi mais alta que a do seixo, independentemente da temperatura ou da velocidade de carregamento. O Módulo de Resiliência e a deformação acumulada nos ensaios de fluência demonstraram que, para as temperaturas de serviço típicas de Manaus (em torno de 40°C), a mistura alternativa tem melhor desempenho que aquela contendo material natural. Contudo, o RCD se mostrou mais susceptível à ação da umidade. Concluiu-se, baseado nos resultados, que forma irregular e a textura superficial rugosa do agregado de resíduo foi responsável por um aumento no atrito entre as partículas no esqueleto estrutural da mistura, colaborando com a resistência ao cisalhamento, especialmente para as temperaturas mais altas de operação, quando a fase viscosa apresenta grande influência no comportamento mecânico.

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.

Aim of the Master’s thesis is analysis of problems of the dangerous goods road transportation, especially transport of flammable liquids. It analyses the European Agreement concerning the International Carriage of Dangerous Goods by Road and its special requirements. Thesis also covers road tanker accidents and the removal of leaked petroleum products. In practical portion the work on resistance testing of asphalt mixtures against several types of fuel is presented.

At the beginning of the Master’s thesis the asphalt mixture of the type asphalt concrete and its basic properties are described. The main point of this work is to compare the functional properties of asphalt mixtures with the addition of higher amount of RAP and various rejuvenators used in the experimental section. From individual samples of asphalt mixtures taken during the laying, the control tests were carried out and the process of permanent deformation with the wheel tracking test was monitored. After that, using functional tests the properties of asphalt mixtures with conventional modified and unmodified asphalt bitumen enriched with the addition of declaring similar properties were compared.

Cold mix asphalt (CMA) emulsion technology could become an attractive option for the road industry as it offers lower startup and equipment installation costs, energy consumption and environmental impact than traditional alternatives. The adhesion between bitumen and aggregates is influenced by diverse parameters, such as changes in surface free energies of the binder and aggregates or the presence of moisture or dust on the surface of aggregates, mixing temperatures, surface textures (including open porosity), nature of the minerals present and their surface chemical composition, as well as additives in the binder phase. The performance of cold asphalt mixtures is strongly influenced by the wetting of bitumen on surfaces of the aggregates, which is governed by breaking and coalescence processes in bitumen emulsions. Better understanding of these processes is required. Thus, in the work this thesis is based upon, the surface free energies of both minerals/aggregates and binders were characterized using two approaches, based on contact angles and vapor sorption methods. The precise specific surface areas of four kinds of aggregates and seven minerals were determined using an approach based on BET (Brunauer, Emmett and Teller) theory, by measuring the physical adsorption of selected gas vapors on their surfaces and calculating the amount of adsorbed vapors corresponding to monolayer occupancy on the surfaces. Interfacial bond strengths between bitumen and aggregates were calculated based on measured surface free energy components of minerals/aggregates and binders, in both dry and wet conditions. In addition, a new experimental method has been developed to study bitumen coalescence by monitoring the shape relaxation of bitumen droplets in an emulsion environment. Using this method, the coalescence of spherical droplets of different bitumen grades has been correlated with neck growth, densification and changes in surface area during the coalescence process. The test protocol was designed to study the coalescence process in varied environmental conditions provided by a climate-controlled chamber. Presented results show that temperature and other variables influence kinetics of the relaxation process. They also show that the developed test procedure is repeatable and suitable for studying larger-scale coalescence processes. However, possible differences in measured parametric relationships between the bitumen emulsion scale and larger scales require further investigation. There are several different research directions that can be explored for the continuation of the research presented in this thesis. For instance, the rationale of the developed method for analyzing coalescence processes in bitumen emulsions rests on the assumption that the results are applicable to large-scale processes, which requires validation. A linear relationship between the scales is not essential, but it is important to be able to determine the scaling function. Even more importantly, qualitative effects of the investigated parameters require further confirmation. To overcome the laboratory limitations and assist in the determination of appropriate scaling functions further research could focus on the development of a three-dimensional multiphase model to study coalescence processes in more detail, including effects of surfactants, pH and other additives such as mineral fillers and salts. Additionally, better understanding of the breaking process and water-push out could help significantly to optimize CMA mix design. Different methods, both numerical and experimental could be explored for this. / Cold mix asphalt (CMA) eller kall asfaltbetong med hjälp av emulsionsteknik kan vara ett attraktivt alternativ för vägbyggnadsindustrin då det möjliggör lägre uppstart- och investeringskostnader, lägre energiförbrukning och mindre miljöpåverkan än traditionella alternativ. Adhesionen mellan bindemedel och stenpartiklarna påverkas av ett flertal parametrar, så som förändring i fri ytenergi hos både bindemedel och partiklar i närvaro av fukt eller damm på stenytorna, blandningstemperatur, yttextur (inklusive ytporositet), mineralegenskaper och ytornas kemiska sammansättning lika väl som tillsatsmedel i bindemedlen. Beteendet hos kall asfaltbetong är starkt påverkad av vätningsegenskaperna hos bindemedlet när det kommer i kontakt med stenmaterialet och detta i sin tur är beroende på bitumenemulsionens brytegenskaper och förmåga att blandas. Bättre förståelse av dessa processer är av största vikt. I detta arbete är avhandlingen baserad på fri ytenergi hos både mineraler/aggregat och bindemedel, baserat på kontaktvinkel och på ångabsorptionsmetoder. Den exakta specifika ytan hos fyra typer av aggregat och sju mineraler undersöktes med en metod baserad på BET (Brunauer, Emmett och Teller):s teorier genom att mäta den fysiska adsorptionen av utvalda gaser på ytorna och beräkna mängden adsorberad ånga som korresponderade mot ytlagret. Styrkan hos kontaktytornas bindning mellan bindemedlet och stenaggregaten beräknades baserat på mätningar av den fria ytenergin hos bägge ingående komponenterna, dels i torrhet dels i våta omgivningar. Som tillägg har en ny experimentell metod utvecklats för att studera bitumens blandbarhet genom att studera bitumendroppars relaxation i en emulsionsmiljö. Genom att använda denna metod har korelationen mellan sväriska droppar av bitumen undersökts mot förändringen i ytans area under blandningsprocessen. Testprotokollet utformades för att studera blandningsprocessen i varierande miljöer i en klimatkammare. Presenterade resultat visar att temperatur och andra variabler påverkar de kinetiska förhållandena vid relaxationsprocessen. De visar även att den utvecklade testmetoden är repeterbar och passar för studier av storskaliga blandningsprocesser. Det bör dock påpekas att vidare studier krävs för att påvisa skillnaderna mellan bitumenemulsionsskalan och större skalor. Framtida forskning kommer att koncentreras på utveckling av tredimensionella multifas­modeller för att studera blandningsförlopp på en mer detaljerad nivå, inkluderande effekter på ytaktiva ämnen, pH-värden och andra additativ så som mineralfiller och salt. Som tillägg kommer nyttan av nya karaktäriseringsmetoder att utvärderas, så som lågvikelspridning av neutroner eller kombinationer av röntgen, neutronradiologi och datortomografi, för att studera brytmekanismer hos bitumenemulsioner vid kontakt med mineraler och aggregat. / <p>QC 20160901</p>

The diploma thesis is focused on the use of R-material in asphalt mixtures with a PMB type binder. The work is divided into a theoretical part and a practical part. The theoretical part describes the acquisition of R-material by road milling, the use of R-material, the binder used in the practical part of the work and the types of recycling. The practical part deals with the design of four types of asphalt mixtures with different content of R-material in the asphalt mixture. It also deals with the description of functional tests of asphalt mixtures and the results of these tests.