Este trabalho descreve um estudo experimental dos efeitos da temperatura em um elemento de pavimento de concreto, construído em laboratório interno e instrumentado com sensores de deformação, deslocamento, força e temperatura. A estrutura foi construída em duas camadas (placa e base) assentadas sobrepostas, sem aderência, sobre um subleito artificial. Os efeitos térmicos foram gerados artificialmente seguindo padrões sazonais da natureza. Os carregamentos estáticos foram realizados por meio de uma máquina hidráulica referenciados a um eixo simples de roda simples. A estrutura foi dimensionada e construída em uma escala de tamanho reduzido, distorcida e montada sobre uma laje de reação. Sob a placa do pavimento foi construído um sistema térmico auto controlado para causar diferencial de temperatura entre o fundo e o topo da placa pela passagem de um fluido. No topo um sistema térmico com controle manual foi construído para gerar gradientes térmicos através da estrutura. Todas as ações foram registradas automaticamente por meio de um sistema de aquisição de dados. Os resultados combinam com os dados da literatura, com experimentos realizados em pistas experimentais e se correlacionam com simulações realizadas por meio de software específico. Isso implica que a metodologia usada é apropriada para ser utilizada em outras situações e experimentos. / This paper describes the experimental study of the effects of temperature on a element of concrete pavement, constructed an internal laboratory and instrumented with sensors of strain, displacement, force and temperature. The structure was built in two layers (slab and base) overlapping settled without grip on an artificial subgrade. The thermal effects were achieved artificially following nature seasonal patterns. The static loads were performed by means of a hydraulic machine referred to a simple wheel axle. The structure was sized and built on distorted small scale and assembled over a slab of reaction. Under the pavement a selfcontrolled heating system was built to cause a temperature gradients between the slab top and bottom from a passing fluid. On the top a manual heating system was built to generate thermal gradients across the structure. All the actions were recorded automatically through a data system. The results agree with the literature data, with experiments performed on experimental roads and correlate themselves with simulations performed by using specific software. This implies that the methodology used is appropriate for use in other situations and experiments.

A presente dissertação teve como objetivos principais delinear um procedimento de análise de sensibilidade que possa ser utilizado de forma ampla por usuários do programa computacional de gerência de pavimentos HDM-4 e analisar a influência de modificações no cenário pré-definido no estudo de caso, notadamente considerações de projeto e de tráfego. A escolha do Método dos Efeitos Elementares foi precedida por uma revisão bibliográfica sobre análise de sensibilidade, sendo que o procedimento foi delineado com um estudo de caso que partiu de um cenário pré-definido (rodovia de pista simples e pavimento asfáltico sobre base granular) e fez a análise da variação de 61 fatores, em 300 trajetórias, totalizando 18.600 simulações no programa HDM-4. Os resultados deste estudo indicaram que a utilização de uma amostra com 30 trajetórias é adequada, pois aumentar este número não acarreta ganhos significativos e a sua diminuição ocasiona prejuízos. Com o procedimento delineado, passou-se à verificação de impactos que a modificação dos cenários pré-definidos para a análise gerariam, ou seja, se a modificação de fatores que não estão no grupo de 61 fatores em estudo interferiria no resultado final do procedimento. Foram estudadas modificações nas considerações de projeto (Taxa de Desconto Monetário Anual e Período de Análise) e nas considerações de tráfego (Percentual de Veículos Comerciais e da Taxa de Crescimento Anual do Tráfego), com os resultados evidenciando que ambas as modificações influem no resultado final da análise de sensibilidade, sendo que as modificações nas considerações de tráfego se mostraram mais influentes que as modificações nas considerações de projeto. Complementarmente, foi feita uma análise de sensibilidade pelo Método dos Efeitos Elementares, com 250 trajetórias, que identificou como os três fatores mais influentes na análise econômica do programa HDM-4, dentro do universo estudado, o Volume Diário Médio Anual de Veículos Motorizados, o Fator de Calibração para a Progressão da Irregularidade Longitudinal e o Fator de Calibração para a Razão do Número Estrutural Ajustado das Estações Úmida e Seca. / This Master of Science Dissertation aimed to outline a procedure for sensitivity analysis that can be widely used by computer program of pavement management HDM-4 users. It also aimed to analyze the influence of changes in the pre-defined scenario of the case study, especially design and traffic considerations. The choice of the Elementary Effects Method was preceded by a literature review on sensitivity analysis, and the procedure was outlined with a case study that came from a pre-defined scenario (two lane standard and asphalt pavement on granular base) and variations of 61 factors, considering 300 trajectories, in a total of 18,600 simulations in HDM-4 program. The results indicated that the use of a sample with 30 trajectories is appropriate, because increasing this number does not cause significant gains and reducing it can harm the analysis. With the procedure outlined, it was checked if changes in factors that are not in the group of 61 studied factors can interfere with the end result. Thus, changes in design (Discount Rate and Period Annual Monetary Analysis) and traffic (Percentage of Commercial Vehicle and Annual Growth Rate of Traffic) considerations affected the final result the sensitivity analysis, and the changes in traffic considerations were more influential than changes in design considerations. In addition, it was conducted a sensitivity analysis by the Elementary Effects Method, with 250 trajectories, which identified as the three most influential factors in the economic analysis of HDM-4 program, within the universe studied, the Annual Average Daily Traffic of Automobiles, the Calibration Factor for the Progression of Longitudinal Roughness and the Calibration Factor for the Ratio of Adjusted Structural Number Wet and Dry Seasons.

The asphalt mixtures are commonly used as surface course of highways to ensure the security and comfort for road users. The asphalt mixtures may also be used as intermediate layers of pavement structure, providing better resistance to traffic loads. Thus, the occurrence of distresses can be reduced, increasing the time between pavement maintenance interventions. Large Stone Asphalt Mixtures (LSAM) are a promising rehabilitation solution for pavements that show rutting as the main distress under heavy traffic situations. Though their use is not new, the study of their viscoelastic properties and performance in the field are still unexplored. This thesis presents a brief literature review about the historical use of LSAM around the world, as well as some relevant characteristics for its design. The evaluation of different mixture design methods was performed before the construction of experimental test site with LSAM as the leveling course. The asphalt mixtures mechanical behavior was characterized using dynamic modulus test, flexural bending fatigue test, tension-compression fatigue test and the LCPC wheel track test. The rehabilitated pavement was monitored through a period of one year and a half, using the falling weight deflectometer and rutting measurements. A finite-layer software (3D-Move Analysis) was used to simulate the structures using dynamic analysis, under different temperatures and traffic speeds, considering the viscoelastic properties of the asphalt mixtures obtained in laboratory. The results from the computer simulations can be used as a guide for the design and analysis of the pavement structure and pavement performance. Thus far, the use of LSAM in the rehabilitated test sections was successful compared to the previous rehabilitation solutions tested in the field, showing no permanent deformation after one year of service life. / O concreto asfáltico é comumente utilizado no Brasil como camada de rolamento em rodovias para garantir a segurança e o conforto dos usuários da via. No entanto, misturas asfálticas também são utilizadas como camadas intermediárias na estrutura do pavimento, atribuindo maior resistência às solicitações do tráfego. Assim, a ocorrência de defeitos pode ser reduzida, aumentando o intervalo entre as intervenções de manutenção do pavimento. Large Stone Asphalt Mixture (LSAM) é uma solução promissora para restauração de pavimentos asfálticos sob tráfego pesado que apresentem, como principal defeito, a deformação permanente em trilha de roda. Embora a sua utilização não seja recente, o estudo das propriedades viscoelásticas e do seu comportamento em campo ainda é pouco explorado. Esta dissertação apresenta uma breve revisão da literatura quanto ao histórico de uso das misturas LSAM ao redor do mundo, assim como características relevantes para a dosagem das mesmas. A avaliação de diferentes métodos de dosagem foi necessária antes da construção de um trecho experimental com a aplicação da LSAM como camada de ligação, onde tal mistura foi caracterizada mecanicamente por meio do ensaio de módulo dinâmico, ensaio de fadiga a flexão em quatro pontos, ensaio de fadiga a tração direta e ensaio de deformação permanente no simulador de tráfego francês LCPC. O pavimento restaurado foi monitorado por um período de um ano e meio com ensaios de \"Falling Weight Deflectometer\" e de afundamento de trilha de roda. As respostas do pavimento submetido a cargas dinâmicas foram analisadas por meio de um software que utiliza o método de camadas finitas (3D-Move), considerando as camadas asfálticas com comportamento viscoelástico linear sob diferentes velocidades de tráfego e temperaturas de análise. Os resultados poderão ser usados como referência para o dimensionamento e a análise das estruturas de pavimento compostas por camada de LSAM e para a avaliação do desempenho do mesmo. O uso da LSAM na restauração das seções experimentais foi bem sucedido quando comparado às restaurações realizadas anteriormente com outras soluções, não apresentando deformação permanente após mais de um ano de vida de serviço.

There is an impetus in the UK to move away from empirical pavement foundation design and the current method specification, towards an analytical design approach. For an analytical design approach to be adopted, the required performance properties of stiffness and resistance to permanent deformation of the foundation materials (sub grade and capping) need to be measured, both in the laboratory for design and in the field in order to ensure compliance. This thesis studies the influence of the sub grade on the constructability and performance of a series of full-scale pavement foundations. This has been achieved by measuring the performance parameters of several sub grade materials in the laboratory, using repeated load triaxial testing. These data have been compared to comparable data collected in situ using dynamic stiffness measuring devices during the construction of trial pavement foundations. The performance of the trial foundations has been measured during the placement and compaction of the different foundation materials, and again after their subsequent trafficking. The testing demonstrates the stress dependency of the foundation materials. The laboratory testing shows that the sub grade permanent deformation under cyclic loading (used to simulate construction operations) becomes unstable at a deviator stress of half the deviator stress at failure (0.5qmax)· The stiffness at this applied stress and above is shown to be approaching a consistent value. This indicates that large changes in the stiffness of inversely stress dependent fine grained soils occur below the deviator stress at which the permanent deformation becomes unstable. Significant variability of data has been found in the performance parameters measured (both in the laboratory and in the field) for samples of subgrade collected from small areas of the same site. However comparable patterns of stress dependency have been observed between measured laboratory and field performance using the different apparatus. The resistance to permanent deformation is shown to be a more critical design load case for construction than the need for adequate stiffness of support required to compact the foundation layers. The performance of a composite road foundation is shown to be material and site specific, and this will have important implications for design and site compliance testing.

Florida Department of Transportation (FDOT) has been using Open Graded Friction Course (OGFC) mixture to improve skid resistance of asphalt pavements under wet weather. The OGFC mixture design strongly depends on the Optimum Binder Content (OBC) which represents if the mixture has sufficient bonding between the aggregate and asphalt binder. At present, the FDOT designs OGFC mixtures using a pie plate visual draindown method (FM 5-588). In this method, the OBC is determined based on visual inspection of the asphalt binder draindown (ABD) configuration of three OGFC samples placed on pie plates with pre-determined trial asphalt binder contents (AC). The inspection of the ABD configuration is performed by trained and experienced technicians who determine the OBC using perceptive interpolation or extrapolation based on the known AC of the above samples. In order to eliminate the human subjectivity involved in the current visual method, an automated method for quantifying the OBC of OGFC mixtures was developed using digital images of the pie plates and concepts of perceptual image coding and neural network (NN). Phase I of the project involved the FM-5-588 based OBC testing of OGFC mixture designs consisting of a large set of samples prepared from a variety of granitic and oolitic limestone aggregate sources used by FDOT. Then the digital images of the pie plates containing samples of the above mixtures were acquired using an imaging setup customized by FDOT. The correlation between relevant digital imaging parameters and the corresponding AC was investigated initially using conventional regression analysis. Phase II of the project involved the development of a perceptual image model using human perception metrics considered to be used in the OBC estimation. A General Regression Neural Network (GRNN) was used to uncover the nonlinear correlation between the selected parameters of pie plate images, the corresponding AC and the visually estimated OBC. GRNN was found to be the most viable method to deal with the multi-dimensional nature of the input test data set originating from each individual OGFC sample that contains AC and imaging parameter information from a set of three pie plates. GRNN was trained by 70% and tested by 30% of the database completed in Phase I. Phase III of the project involved the configuration of a quality control tool (QCT) for the aforementioned automated method to enhance its robustness and the likelihood of implementation by other agencies and contractors. QCT is developed using three quality control imaging parameters (QCIP), orientation, spatial distribution, and segregation of ABD configuration of pie plate specimens (PPS) images. Then, the above QCIP were evaluated from PPS images of a variety of independent mixture designs produced using the FDOT visual method. In general, this study found that the newly developed software (GRNN-based) provides satisfactory and reliable estimations of OBC. Furthermore, the statistical and computer-generated results indicated that the selected QCIP are adequate for the formulation of quality control criteria for PPS production. It is believed that the developed QCT will enhance the reliability of the automated OBC estimation image processing-based methodology.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第16377号 / 工博第3458号 / 新制||工||1523(附属図書館) / 29008 / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 小林 潔司, 教授 大津 宏康, 教授 河野 広隆 / 学位規則第4条第1項該当

Die Dimensionierung einer Betonfahrbahn zielt darauf ab, den Anteil der im Nutzungszeitraum versagenden Platten auf ein akzeptables Maß zu begrenzen. Der Anteil ausgefallener Platten entspricht der Versagenswahrscheinlichkeit der einzelnen Platte. Damit ergibt sich die Notwendigkeit, die Versagenswahrscheinlichkeit zu berechnen. Innerhalb der vorliegenden Arbeit werden grundlegende Methoden und Verfahrensweisen zur Lösung dieser Aufgabe entwickelt. Es wird gezeigt, wie die für die Quantifizierung der Versagenswahrscheinlichkeit entscheidenden Streuungen der Einflussgrößen mathematisch beschrieben und im Dimensionierungsverfahren berücksichtigt werden können. Dabei wird regelmäßig Bezug genommen auf das in Deutschland eingeführte Dimensionierungsmodell der RDO Beton [2]. Die Grundlage für die Berechnung der Versagenswahrscheinlichkeit liefern die Methoden der Statistik und Wahrscheinlichkeitsrechnung, sowie der Zuverlässigkeitstheorie. Es wird gezeigt, dass sowohl die mathematisch exakte Lösung, wie auch verschiedene Näherungsverfahren für die Problematik der Betonfahrbahnen anwendbar sind. Näher untersucht werden die Zuverlässigkeitstheorie 1. Ordnung (FORM) sowie die Monte-Carlo-Methode. Die jeweiligen Vor- und Nachteile werden analysiert. Es zeigt sich, dass für die Anwendung des FORM-Algorithmus das Berechnungsmodell der RDO Beton modifiziert werden muss. Der zeitliche Bezug der Berechnung kann über die Benutzung von Extremwertverteilungen, die Modellierung stochastischer Prozesse oder die Einführung einer Schadensakkumulationshypothese hergestellt werden. Besondere praktische Bedeutung hat die Berechnung der Versagenswahrscheinlichkeit für den Nutzungszeitraum mit zeitlich varianten Bedingungen. Für diesen Fall werden vier verschiedene Lösungsansätze aufgezeigt. Um die teilweise sehr hohen Rechenzeiten zu minimieren, werden Näherungslösungen entwickelt. Die praktische Eignung wird mit beispielhaften Berechnungen demonstriert. Es zeigt sich, dass die Berechnungsergebnisse stark davon abhängen, wie sich die Werte einzelner Parameter über den Nutzungszeitraum entwickeln. Die betreffenden zeitlichen Verlaufsfunktionen sind gegenwärtig nur unzureichend bekannt. Um eine hinreichend verlässliche Prognose zu berechnen, sind alle Berechnungsverfahren möglichst objektbezogen zu kalibrieren. / The dimensioning of a concrete pavements aims to limit the percentage of failing slabs to an acceptable level. The proportion of failed slabs corresponds to the probability of failure of each slab. This results in the need to calculate the probability of failure. Within the present work, basic methods and procedures for solving this problem are being developed. It is shown how the variations of parameters can be mathematically described and considered in the dimensioning process. Reference is frequently made to the model of RDO Beton [2]. The methods of statistics and probability theory, and reliability theory provide the basis for calculating the probability of failure. It is shown that both the mathematically exact solution and various approximation methods as well are applicable to the problem of concrete pavements. Be examined more closely the reliability theory 1st order (FORM) and Monte Carlo method. The respective advantages and disadvantages are analyzed. It turns out that the calculation model of the RDO concrete has to be modified for the use of FORM algorithm. The temporal relation of the calculation can be made on the use of extreme value distributions, modeling of a stochastic process or the introduction of a damage accumulation hypothesis. Particular practical significance has to calculate the probability of failure for the period of use with time-variant conditions. In this case, four different approaches are discussed. Approximate solutions to minimize the sometimes very high computation times has been developed. The practical suitability is demonstrated by exemplary calculations. It turns out that the calculation results depend strongly on how to develop the values of individual parameters over the period of use. These time course functions are insufficiently known at present. To calculate a sufficiently reliable forecast, all calculation methods are possible to calibrate object-related.

The negative impacts associated with highway pavement rehabilitation projects drove state highway agencies (SHAs) towards increased adoption of alternative contracting methods (ACMs) to accelerate the construction of such projects; hence, reducing these impacts on the travelling public. However, the application of such methods showed mixed results due to the lack of specific guidelines addressing the adoption of such methods and the selection of the best ACM for each project. This lack of guidelines stems from the lack of research studies examining the impact of each of these methods on the time/cost trade-off relationship in highway rehabilitation projects. Existing literature includes several studies aimed at developing generic and subjective guidelines based on past experiences that do not take into consideration the unique nature of each of these methods. Hence, this research study aimed at analyzing the SHAs’ decision making process regarding two of the most-widely used ACMs: Incentive/Disincentive (I/D) and Cost + Time (A+B) contracting methods, in order to support decision makers in choosing the most-suitable method for their projects. To this end, two models were developed in this dissertation to examine the time/cost trade-off for each method using simulation and regression analysis. Each model was validated against real-life projects and used to assign appropriate ID and “B” values based on the SHA’s desired duration reduction and available budget. Furthermore, a risk analysis module was developed to determine the most-likely duration reduction that the contractor can achieve for each project under each method. The developed models should help improve the decision making process regarding the selection and implementation of these methods in highway rehabilitation projects. For example, the models can help SHAs identify the minimum ID level that can be offered for each project and the expected duration that the contractors can bid on under the A+B contracting method. Finally, the models were contrasted and applied to real-life projects with different characteristics to verify existing guidelines and establish the candidate ACM for each project category. The findings of this study will benefit the society, SHAs, and the economy in general by optimizing the use of available time and money resources.

Despite the widespread recycling of Reclaimed Asphalt Pavement (RAP), a large portion of it is still wasted. One of the main reasons is the concern with the performance of high RAP mixtures. Asphalt binder aging and subsequent rejuvenation is one source of uncertainty. Rejuvenators are frequently added to high RAP mixes to enhance the properties of the binder. This enhancement is often perceived as simply lowering the viscosity. Two important parameters that are not adequately addressed by existing methods are durability and homogeneity of the recycled binder. This research investigated these two concerns and provided quantitative indicators to measure them. The durability of rejuvenated binders was investigated through studying their long-term aging. Superpave PG tests and aging procedures were used for this purpose. Results indicated that the type and dosage of the rejuvenator has a significant impact on the aging of a rejuvenated binder. While using a proper rejuvenator can prolong the life of the binder, choosing a wrong product causes the binder to age significantly faster. The asphalt film that coats aggregates is not necessarily homogeneous. Different layers of the film are affected differently by aging and rejuvenation processes. A staged extraction method was implemented to provide representative samples from the different layers of asphalt. The stiffness of each sample was measured by Dynamic Shear Rheometer testing. Results indicated that most of the rejuvenator is absorbed by outer layers immediately after blending. As the mixture ages, the rejuvenator continues diffusing into the inner layers. Outer layers are also affected more intensely by the aging. The coupled effects of aging and rejuvenation make the recycled binder more homogeneous than virgin asphalt. This property can facilitate the use of higher target PG values for recycled binders without compromising the long-term performance. This research introduces two quantitative measures, critical PAV time and Durability Index, for evaluating the durability of recycled binders and two other parameters, Stiffness Gradient Factor and Homogeneity Index for describing the binder film homogeneity. These indicators and the knowledge obtained from this research make it possible to design and evaluate the binder rejuvenation process in a more effective manner.

Dowel bars are provided at the transverse joints of the Jointed Plain Concrete Pavement (JPCP) to transfer the load between adjoining slabs and to allow for expansion and contraction of the pavement due to temperature and moisture changes. The current study involved evaluation of the performance of Glass Fibre Reinforced Polymer (GFRP) dowels in JPCP as an alternative to the conventional epoxy-coated steel dowel bars, especially in the presence of dowel misalignment. This research involved two main sets of experimental tests. The first set focused on the evaluation of load-deflection response of GFRP dowels using a scaled model of pavement slabs. The second set investigated the combined effect of dowel misalignment and cyclic wheel load on the performance of steel and GFRP dowels. The tested slabs (in the second set) were supported on a steel-beam base with stiffness such that the effects of the underlying layers of real pavements are incorporated. In both of these sets of experiment the GFRP dowels were compared with the steel dowels of similar flexural rigidity. The research also involved detailed numerical investigations using ABAQUS for all experimental tests in the current study. The validated numerical model was used to conduct three sets of parametric studies: to propose design considerations for the GFRP dowels; to simulate all important cases of dowel misalignment (111 cases) for steel and GFRP dowels and to give an insight into the damaged volume in the surrounding concrete pavement; and to investigate the effects of diameter, length and type of dowel bar, concrete grade, pavement thickness, and slab-base friction on the joint-opening behaviour. The results from the first set of experiments showed that the 38 mm GFRP dowels perform better in terms of deflection response compared to the 25 mm steel dowels. Also, it was observed that the relative deflection (RD) is more sensitive to the changes in the joint width rather than the concrete strength. The numerical results from the first set showed a good agreement with the experimental results and showed lower magnitude and better distribution of stress in the concrete underneath the GFRP dowels as compared with the steel dowels. Finally, on the basis of a detailed parametric study (70 different cases), design considerations for GFRP dowels in JPCP were suggested. The second set of experimental results showed that the GFRP dowels can withstand a cyclic traffic load and significantly reduce joint lockup and dowel looseness (DL) and can provide sufficient load transfer efficiency (LTE). It was also observed that the dowel misalignment affects DL significantly more than the repeated traffic load. Slab-base separation and the orientation of misaligned dowels have significant effects on the pull-out load required to open the joint. The numerical results from the second set indicated that the pull-out load was small for the vertical misalignment cases compared to the horizontal and combined misalignment cases. The results also indicated the occurrence of concrete spalling and deterioration at smaller joint openings for combined misalignment when compared to other misalignment types. The use of GFRP dowels significantly reduced the pull-out load and joint lockup when dowel misalignment exists. Consequently, the deterioration of the surrounding pavement substantially decreased. The long term performance of the JPCP fitted with GFRP dowels improves because of a reduction in the DL and the RD, and by maintaining a good LTE even for misaligned dowels. The numerical results also showed that the pull-out load increases significantly for an increase in the concrete compressive strength and the dowel bar diameter. Small increase in pull-out load was observed for higher embedded length of the dowel bar, whereas the increase was insignificant for an increase in the pavement thickness and slab-base friction. In general, the study showed the GFRP dowel can be a potential alternative for the conventional steel dowel bars in JPCP.