In most road infrastructure networks, the two prevalent types of pavements considered during the pavement type selection (PTS) process are flexible and rigid. Thus, these two structures are the most commonly constructed in the road industry. A consideration of a different pavement alternative is proposed in this study. Composite pavements, which are in essence a combination of a rigid base overlaid with a hot-mix asphalt (HMA) surface course, have the potential to meet the technical and economic requirements that are sought in the PTS process. For that reason, technical and economic evaluations were performed to justify the consideration of composite pavement systems in the PTS process. At the technical level, composite pavement design guidelines from various transportation agencies were obtained and followed to design their respective composite pavement structures. A mechanistic analysis based on the multi-layer linear elastic theory was performed on different composite structures to understand the behavior they present when compared to traditional pavements. In addition, distresses affecting composite pavements such as fatigue (bottom-up and top-down) cracking, rutting, and reflective cracking were modeled and investigated using sensitivity analyses. At the economic level, a deterministic life cycle cost analysis (LCCA) based on Virginia Department of Transportation (VDOT) guidelines was performed. This LCCA compared two proposed composite pavements (one with a cement-treated base [CTB] and the other with a continuously reinforced concrete pavement [CRCP] base) to traditional flexible and rigid pavement structures. Furthermore, sensitivity analyses involving discount rates and traffic volumes were performed to investigate their effect on the present worth (PW) computation of the four pavement alternatives. Results from this study suggest that composite pavements have both the technical and economic potential to be considered during the PTS process. / Master of Science

The objective of this study is to characterize the properties of typically adopted drainage layer materials in VA, OK, and ID. A series of laboratory tests have been conducted to quantify the volumetric properties, permeability and mechanical properties of the laboratory-compacted asphalt treated and cement treated permeable base specimens. The modified test protocols to determine the dynamic modulus of the drainage layer materials have been provided, which can be followed to determine the dynamic modulus of the drainage layers as level 1 input in Mechanistic-Empirical (M-E) pavement design. The measured dynamic moduli have been used to calibrate the original NCHRP 1-37A model to facilitate its application on drainage layer materials for prediction of the dynamic modulus as level 2 input. The compressive strength of the cement treated permeable base mixture of different air void contents has also been quantified in laboratory. Numerical simulations are conducted to investigate the location effects and the contribution of the drainage layer as a structural component within pavement. The optimal air void content of the drainage layer is recommended for Virginia, Oklahoma and Idaho based on the laboratory-determined permeability and the predicted pavement performances during 20-year service life. / Ph. D.

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.

O comportamento mecânico do subleito tem influência determinante no desempenho das estruturas de pavimento. Porém, muitas vezes, os estudos realizados para elaboração de projetos são simplistas e não levam em conta as variações de comportamento mecânico que podem ocorrer, seja por fatores construtivos, seja ambientais, como umidade, durante o período de operação. Neste sentido, métodos de dimensionamento mecanicistas-empíricos de estruturas de pavimentos empregam modelos de comportamento das diversas camadas da estrutura e do subleito, sendo alvos de constantes revisões para recalibração destes modelos, de modo que se aproximem mais da realidade do comportamento em serviço. As calibrações dos modelos são necessárias para aumentar a confiabilidade do dimensionamento de modo a garantir pavimentos mais duráveis, e para otimizar custos de execução e de manutenção ao longo da vida útil das estruturas. Neste contexto o presente trabalho propõe uma metodologia para compreender as propriedades dos solos do subleito e de suas variações, estabelecendo um programa de ensaios de campo e de laboratório, cadastramento, processamento e combinação de resultados de propriedades físicas e mecânicas de solos de subleitos de pavimentos de rodovias existentes. O objetivo final é estabelecer parâmetros de deformabilidade elástica de solos do subleito e sua variabilidade para auxiliar no dimensionamento de novas estruturas de pavimentos e reabilitação das antigas. O trabalho utiliza estudos de casos de pavimentos rodoviários em operação. O primeiro caso foi base para o estabelecimento metodológico de estudo desejável do subleito de um pavimento existente, concebendo modelos de previsão de comportamento resiliente do subleito para uso em futuros projetos de restauração deste pavimento ou para novos projetos em locais com similaridade de ocorrência de solos. Empregando a metodologia estabelecida no primeiro caso, fez-se uma busca minuciosa de dados em vários documentos existentes sobre pavimentos rodoviários de concessionárias do Estado de São Paulo, concebendo-se um banco de dados para análise do subleito destes pavimentos, de modo a ampliar a gama de solos pesquisados. Com resultados de caracterização de solos em laboratório e de deflectometria em campo, além de dados de localização dos pontos estudados em mapas geológicos e pedológicos, dados de precipitação, de terraplenagem, entre outros, pôde-se analisar os dados e identificar a influência de cada elemento na variação do módulo de resiliência dos solos de fundação de pavimentos em serviço. O banco de dados de ensaios laboratoriais de solos de subleito contou com um total de 3.894 registros e de ensaios não destrutivos deflectométricos de campo com um total de 169.525 registros (dados históricos de nove rodovias estaduais diferentes). Dentre as principais conclusões, verificou-se que grande parte dos modelos de correlações existentes na literatura entre parâmetros de propriedades físicas e de resistência (como CBR) de solos com o módulo de resiliência possui aplicação muito restrita, inviabilizando sua aplicação de forma indiscriminada em locais distintos daqueles onde foram obtidas as correlações. Além disso, verificou-se que o módulo de resiliência do subleito em campo apresenta variações de grande magnitude e, portanto, é de difícil previsão, requerendo acumulação de dados históricos, bem como de um cadastro adicional de maior gama de informações. Recomenda-se que maiores quantidades de ensaios sejam realizadas e que permitam verificação, ou dupla checagem, para validação, bem como para futuramente ser possível o estabelecimento de modelos matemáticos mais confiáveis. Nos estudos, foi possível estabelecer parâmetros estatísticos que podem ser utilizados tanto em métodos de dimensionamento vigentes ou novos, como naquelas que consideram as variações do módulo de resiliência do subleito para determinação do risco de falha, ou da confiabilidade das estruturas. / Subgrade mechanical behavior has a determining influence on the performance of pavement structures. However, often, the studies carried out for project designs are simplistic and do not take into account the variations that can occur in the mechanical behavior, whether by constructive factors or environmental ones, such as the moisture content during the operation period. Thus, mechanical-empirical design methods of pavement structures employ performance models of the many layers of the structure and of the subgrade, being targets of constant revisions for adjustment of these models so that they come closer to reality in operation behavior. Model adjustments are necessary to increase design reliability to ensure more durable pavements and to optimize execution and maintenance costs during the structure life. In this context, the present work proposes a methodology to understand the subgrade soil properties and their variations, establishing a program of field and laboratory tests, registration, processing and combination of results of physical and mechanical properties of subgrade soils of existing highway pavements. The final objective is to establish parameters of the subgrade soil elastic deformability and their variability to assist in the design of new pavement structures and in the rehabilitation of old ones. This work uses case studies of road pavements in operation. The first case was the basis for the methodological establishment of a desirable study of the subgrade of an existing pavement, designing predictive models of the subgrade resilient behavior for use in future rehabilitation projects of this pavement or for new projects in places with a similar occurrence of soils. By using the methodology established in the first case, a thorough data search was carried out in several existing documents on road pavements of concessionaires in the State of São Paulo, and a database was prepared to analyze the subgrade of such pavements in order to expand the range of soils studied. With the results of soil characterization in the laboratory and by field deflections, in addition to location data of the points studied in geological and pedological maps, precipitation and earthwork data, among others, it was possible to analyze the data and identify the influences of each element on the variation of the subgrade resilient modulus of the pavements in operation. The database from laboratory tests of subgrade soils covered a total of 3,894 registers and of non-destructive deflectometric field tests - a total of 169,525 registers (historical data on nine different state highways). Among the main conclusions, it was verified that most of the correlation models existing in the literature between parameters of physical and mechanical strength properties (like the CBR) of soils with the resilient moduli have very restricted application, making it impossible to apply them indiscriminately in places other than those where the correlations were obtained. In addition, it was verified that the resilient modulus of the subbase in situ presents variations of great magnitude and, therefore, it is difficult to make predictions. Lots of historical data are required, as well as additional registers of a greater range of information. Therefore, it is recommended that a larger number of tests be performed in order to allow for checking and double-checking for validation as well as the possibility of a future establishment of more reliable mathematical models. In the studies, it was possible to establish statistical parameters that can be used both in current and in new design methods, like in those that consider variations of the subgrade resilient moduli to determine the risk of failure or of the reliability of structures.

Doctor of Philosophy / Department of Civil Engineering / Mustaque A. Hossain / Stacey E. Kulesza / Recycled concrete aggregate (RCA) is the byproduct of the demolition of concrete structures and pavements. An estimated 140 million tons of concrete waste is produced annually in the United States, most of which ends up in landfills. The use of RCA to replace quarried aggregates in paving projects is one way to utilize these materials and alleviate concerns regarding this increasing waste stream. RCA usage prevents waste concrete disposal into landfills, resulting in more sustainable use of mineral aggregate sources, and may further reduce costs associated with paving projects. However, the inferior physical properties of RCA, such as the presence of recycled mortar, complicate the incorporation of RCA into new concrete mixtures. State highway agencies such as the Kansas Department of Transportation are facing further issues with RCA from D-cracked pavements, raising the question if D-cracked aggregates should be used in paving operations. No known work has evaluated the effect of RCA from D-cracked pavements in subgrade soil stabilization. This study stabilized a low-plasticity clay in Kansas using RCA and three stabilizing materials (lime, Class C fly ash, and a combination of Portland cement and fly ash). Candidate mixtures with varying proportions of chemical stabilizers and D-cracked aggregates were evaluated using the standard Proctor, unconfined compressive strength, linear shrinkage, and California Bearing Ratio tests. Microstructure characteristics of selected mixtures were explored using scanning electron microscopy (SEM) and energy dispersive X-ray tests. Laboratory test results indicated that RCA, in conjunction with all cementitious materials except lime, improved clay strength, stiffness, and shrinkage properties. SEM results indicated that RCA caused a low void space and a dense arrangement of soil particles. RCA effectively improved evaluated mixture properties when an adequate soil-RCA bond was reached using chemical agents. The long-term performance of full-depth flexible pavements with stabilized mixtures as subgrade was assessed in the AASHTOWare Pavement ME Design (commonly known as MEPDG) software. The life-cycle cost of flexible pavements with stabilized mixtures was estimated for a 40-year design period. Economic analysis results indicated that RCA was cost effective only if it was used with a combination of fly ash and Portland cement.

The objective of this research was to apply a previously recommended laboratory testing protocol to specific aggregate base materials that are also the subject of ongoing full-scale field testing. The scope of this research involved three aggregate base materials selected from three sites where full-scale field testing programs have been established. The first and second field sites included five different geogrid types, categorized as either biaxial or triaxial, in a singlelayer configuration, while the third site included only the triaxial geogrid type in either a singleor double-layer configuration. Geogrid-stabilized and unstabilized control specimens were evaluated using the American Association of State Highway and Transportation Officials T 307 quick shear testing protocol. Measurements of load and axial displacement were recorded and used to develop a stress-strain plot for each specimen tested. The peak axial stress, the modulus to the peak axial stress, the modulus of the elastic portion of the curve, and the modulus at 2 percent strain were then calculated. Statistical analyses were performed to investigate differences between geogridstabilized specimens and unstabilized control specimens and to investigate differences between individual geogrid products or geogrid configurations. Depending on the method of data analysis, the quick shear test results indicate that geogrid stabilization, with the effect of geogrid stabilization averaged across all of the geogrid products evaluated in this study, may or may not improve the structural quality of the aggregate base materials evaluated in this study. The results also indicate that, regardless of the method of analysis, one geogrid product or configuration may be more effective than another at improving the structural quality of a given aggregate base material as measured using the quick shear test. All results from this research are limited in their application to the aggregate base material types, geogrid products, and geogrid configurations associated with this study. Additional research is needed to compare the results of the laboratory quick shear testing obtained for this study with the structural capacity of the geogrid-stabilized and unstabilized control sections that have been constructed at corresponding full-scale field testing sites. Specifically, further research is needed to determine which method of laboratory data analysis yields the best comparisons with field test results. Finally, correlations between the results of quick shear testing and resilient modulus need to be investigated in order to incorporate the findings of the quick shear test on geogrid-stabilized base materials into mechanistic-empirical pavement design.

Transport infrastructures such as roads are assets for the society as they not only ensure mobility but also strengthen society’s economy. Considerable amount of energy and materials, that include bitumen, aggregates and asphalt, are required to build and maintain roads. Improper utilization of energy and/or use of materials may lead to more waste and higher costs. The impact on the environment cannot be neglected either. Life cycle assessment (LCA) as a method can be used to assess the environmental impacts of a road system over its entire life time. Studying the life cycle perspective of roads can help us improve the technology in order to achieve a system that has a lower impact on the environment. There are number of LCA tools available. However, implementation of such tools is still unseen in real road projects. This clearly indicates that there are gaps which are needed to be filled in order to bring these tools into practice. An open road LCA framework was developed for the asphalt roads in order to help in decision support at the late project planning stage such as that related to the green procurement. The framework takes into account the construction, maintenance and end of life phases and focuses on energy and greenhouse gas (GHG) emissions. Threshold values for the production of some additives were also determined to show how LCA tools can help material suppliers to improve the road materials production processes and the road authorities to set limits on the use of different materials based on the environmental criteria. Additive consideration and feedstock energy in road LCAs were also identified as gaps that were looked in detail. The attributes that are important to consider in an asphalt road LCA that seeks to serve as a decision support in a procurement situation are described. A brief literature review was carried out that focused on project LCAs, and specifically those considering pavements, as this level is assumed to be appropriate for questions relevant in a procurement situation. Following the different standards; road LCAs developed all over the world have generated a lot of knowledge and the studies have been different from each other such as in terms of goals and system boundaries. Hence, the patterns observed have been very different from study to study. It was also difficult to assess the decision support level for which the various LCA frameworks or tools were developed. It is important to define system boundaries based on where in the system the decision support is needed. For LCA to be useful for decision support in a procurement situation, it is important to have a clear understanding of the attributes that constitute the life cycle phases and how data of high quality for them are obtained. The level of consistency and transparency of road LCAs becomes increasingly important in pre-procurement and procurement situations. The key attributes used in a road LCA should mirror the material properties used in a pavement design and therefore be closely linked to the performance of the road in its life cycle. From the different case studies, it was found that asphalt production and transportation of materials are usually highest in the energy and GHG emissions chain. It is highly favorable to have the quarry site, the asphalt plant and the construction site not far from each other and to use the electricity that has been produced in an efficient way. Based on the laboratory test results, it is shown that the effects of chemical warm mix asphalt additives (WMAA)s must be evaluated on a case by case basis since WMAA interaction with the aggregate surface mineralogy appears to play a significant role and thus affects its long term structural behavior. Using the material properties obtained from the Superpave indirect tensile test (IDT) results, pavement thickness design was done in which Arlanda aggregate based asphalt mixtures resulted in thinner pavements as compared to Skärlunda aggregate based asphalt mixtures for the same design life period. Energy (feedstock and expended) saving and reduction in GHG emissions were also seen with addition of WMAA, for both aggregate type cases, based on the data used. Importantly, the results presented illustrate the importance of a systems based LCA approach for evaluating the sustainability for different design and construction options. In this context, having actual pavement material properties as the key attributes in the LCA enables a pavement focused assessment of environmental costs associated with different design options. / <p>QC 20141118</p>

O comportamento mecânico do subleito tem influência determinante no desempenho das estruturas de pavimento. Porém, muitas vezes, os estudos realizados para elaboração de projetos são simplistas e não levam em conta as variações de comportamento mecânico que podem ocorrer, seja por fatores construtivos, seja ambientais, como umidade, durante o período de operação. Neste sentido, métodos de dimensionamento mecanicistas-empíricos de estruturas de pavimentos empregam modelos de comportamento das diversas camadas da estrutura e do subleito, sendo alvos de constantes revisões para recalibração destes modelos, de modo que se aproximem mais da realidade do comportamento em serviço. As calibrações dos modelos são necessárias para aumentar a confiabilidade do dimensionamento de modo a garantir pavimentos mais duráveis, e para otimizar custos de execução e de manutenção ao longo da vida útil das estruturas. Neste contexto o presente trabalho propõe uma metodologia para compreender as propriedades dos solos do subleito e de suas variações, estabelecendo um programa de ensaios de campo e de laboratório, cadastramento, processamento e combinação de resultados de propriedades físicas e mecânicas de solos de subleitos de pavimentos de rodovias existentes. O objetivo final é estabelecer parâmetros de deformabilidade elástica de solos do subleito e sua variabilidade para auxiliar no dimensionamento de novas estruturas de pavimentos e reabilitação das antigas. O trabalho utiliza estudos de casos de pavimentos rodoviários em operação. O primeiro caso foi base para o estabelecimento metodológico de estudo desejável do subleito de um pavimento existente, concebendo modelos de previsão de comportamento resiliente do subleito para uso em futuros projetos de restauração deste pavimento ou para novos projetos em locais com similaridade de ocorrência de solos. Empregando a metodologia estabelecida no primeiro caso, fez-se uma busca minuciosa de dados em vários documentos existentes sobre pavimentos rodoviários de concessionárias do Estado de São Paulo, concebendo-se um banco de dados para análise do subleito destes pavimentos, de modo a ampliar a gama de solos pesquisados. Com resultados de caracterização de solos em laboratório e de deflectometria em campo, além de dados de localização dos pontos estudados em mapas geológicos e pedológicos, dados de precipitação, de terraplenagem, entre outros, pôde-se analisar os dados e identificar a influência de cada elemento na variação do módulo de resiliência dos solos de fundação de pavimentos em serviço. O banco de dados de ensaios laboratoriais de solos de subleito contou com um total de 3.894 registros e de ensaios não destrutivos deflectométricos de campo com um total de 169.525 registros (dados históricos de nove rodovias estaduais diferentes). Dentre as principais conclusões, verificou-se que grande parte dos modelos de correlações existentes na literatura entre parâmetros de propriedades físicas e de resistência (como CBR) de solos com o módulo de resiliência possui aplicação muito restrita, inviabilizando sua aplicação de forma indiscriminada em locais distintos daqueles onde foram obtidas as correlações. Além disso, verificou-se que o módulo de resiliência do subleito em campo apresenta variações de grande magnitude e, portanto, é de difícil previsão, requerendo acumulação de dados históricos, bem como de um cadastro adicional de maior gama de informações. Recomenda-se que maiores quantidades de ensaios sejam realizadas e que permitam verificação, ou dupla checagem, para validação, bem como para futuramente ser possível o estabelecimento de modelos matemáticos mais confiáveis. Nos estudos, foi possível estabelecer parâmetros estatísticos que podem ser utilizados tanto em métodos de dimensionamento vigentes ou novos, como naquelas que consideram as variações do módulo de resiliência do subleito para determinação do risco de falha, ou da confiabilidade das estruturas. / Subgrade mechanical behavior has a determining influence on the performance of pavement structures. However, often, the studies carried out for project designs are simplistic and do not take into account the variations that can occur in the mechanical behavior, whether by constructive factors or environmental ones, such as the moisture content during the operation period. Thus, mechanical-empirical design methods of pavement structures employ performance models of the many layers of the structure and of the subgrade, being targets of constant revisions for adjustment of these models so that they come closer to reality in operation behavior. Model adjustments are necessary to increase design reliability to ensure more durable pavements and to optimize execution and maintenance costs during the structure life. In this context, the present work proposes a methodology to understand the subgrade soil properties and their variations, establishing a program of field and laboratory tests, registration, processing and combination of results of physical and mechanical properties of subgrade soils of existing highway pavements. The final objective is to establish parameters of the subgrade soil elastic deformability and their variability to assist in the design of new pavement structures and in the rehabilitation of old ones. This work uses case studies of road pavements in operation. The first case was the basis for the methodological establishment of a desirable study of the subgrade of an existing pavement, designing predictive models of the subgrade resilient behavior for use in future rehabilitation projects of this pavement or for new projects in places with a similar occurrence of soils. By using the methodology established in the first case, a thorough data search was carried out in several existing documents on road pavements of concessionaires in the State of São Paulo, and a database was prepared to analyze the subgrade of such pavements in order to expand the range of soils studied. With the results of soil characterization in the laboratory and by field deflections, in addition to location data of the points studied in geological and pedological maps, precipitation and earthwork data, among others, it was possible to analyze the data and identify the influences of each element on the variation of the subgrade resilient modulus of the pavements in operation. The database from laboratory tests of subgrade soils covered a total of 3,894 registers and of non-destructive deflectometric field tests - a total of 169,525 registers (historical data on nine different state highways). Among the main conclusions, it was verified that most of the correlation models existing in the literature between parameters of physical and mechanical strength properties (like the CBR) of soils with the resilient moduli have very restricted application, making it impossible to apply them indiscriminately in places other than those where the correlations were obtained. In addition, it was verified that the resilient modulus of the subbase in situ presents variations of great magnitude and, therefore, it is difficult to make predictions. Lots of historical data are required, as well as additional registers of a greater range of information. Therefore, it is recommended that a larger number of tests be performed in order to allow for checking and double-checking for validation as well as the possibility of a future establishment of more reliable mathematical models. In the studies, it was possible to establish statistical parameters that can be used both in current and in new design methods, like in those that consider variations of the subgrade resilient moduli to determine the risk of failure or of the reliability of structures.

abstract: The major challenge for any pavement is the freight transport carried by the structure. This challenge is expected to increase in the coming years as freight movements are projected to grow and because these movements account for most of the load related distresses for the pavement. Substantial effort has been devoted to identifying the impacts of these future national freight trends with respect to the environment, economic growth, congestion, and reliability. These are all important aspects relating to the freight question, but an equally important and often overlooked aspect of this issue involves the impact of freight trends on the physical infrastructure. This study analyzes the impact of future freight traffic trends on 26 major interstates representing 68% of the total system mileage and carrying 80% of the total national roadway freight. The pavement segments were analyzed using the Mechanistic Empirical Pavement Design Guide software after collecting the relevant traffic, climate, structural, and material properties. Comparisons were drawn between the expected pavement performance using current design standards for traffic growth and performance predictions that incorporated more detailed freight projections which themselves considered job growth and six key drivers of freight movement. The differences in the resultant performance were used to generate maps that provide a bird’s eye view of locations that are especially vulnerable to future trends in freight movement. The analysis shows that the areas of greatest vulnerability include segments that are directly linked to the busiest ports, and surprisingly those from Atlantic and Central states that provide long distance connectivity, but do not currently carry the highest traffic volumes. / Dissertation/Thesis / Masters Thesis Civil and Environmental Engineering 2016

The Brazil as a country road, which needs much its highways, however, currently the country uses for PAVEMENT scaling of a method developed in 1966 and updated in 1981 by Murilo Souza Engineer extinct DEER. The method that your main idea it is sizing foundation which is in the CBR, based on the empirical method. This way , along the growing fleet of the country and the emergence of some works of mechanistic-empirical nature, this work aims to make the analysis of a pavement through DNIT method and software use SisPavBR developed by Felipe Franco in their studies that began in 2007 in his thesis, making the adjustment and calibration of some performance prediction models .Similarly, We also did the use the AASHTOWare Pavement software developed by AASHTO as well as determining the thickness of the coating layer required to meet the demands imposed on the floor by means of mechanistic and empirical methods. For this, was then done using vehicle counting performed to BR116, however, they were necessary to create traffic volume of tracks (N) due DNIT method does not consider the arrangement of axes that SisPavBR and AASHTO are in their reviews .It was also conducted a survey of the executive cost km deck sized for each method, and statistical analysis was performed by AASHTO with variations in thickness of the coating base, subbase, base resilience modules, sub-base, subgrade and the volume of traffic to determine which of these variables cause greater interference on performance criteria. Thus, it was found that the surface scaled by DNIT need a coating thickness of 12.5 cm, the need SisPavBR 19.5 cm and 40 cm AASHTO needed, as the cost of the pavement was more higher for the dimensioning and AASHTO DNIT and SisPavBR had closest costs. The life time of DNIT pavement scaling was well below expectations in both analyzes, arriving in a case last only two months. Statistical analysis determined five equations to determine the deterioration mechanisms with R² above 0.85; it was determined that the major variables that affect the performance of flexible pavements are traffic volume and thickness of the coating. / O Brasil como um país rodoviário, necessita muito de suas rodovias, no entanto, atualmente o país faz uso para dimensionamento de pavimentos de um método desenvolvido em 1966 e atualizado em 1981, pelo Engenheiro Murilo Souza do extinto DNER. Método este que seu principal fundamento de dimensionamento está no CBR, baseando-se no método empírico. Desta forma, juntamente à crescente frota do país e com o surgimento de alguns trabalhos de cunho mecanístico-empírico, este trabalho tem como objetivos, fazer a análise de um pavimento por meio do Método do DNIT e do uso do software SisPavBR desenvolvido por Felipe Franco em seus estudos que iniciaram em 2007 em sua tese, realizando o ajuste e calibração de alguns modelos de previsão de desempenho. Da mesma forma, foi utilizado também o software AASHTOWare Pavement desenvolvido pela AASHTO, bem como a determinação da espessura da camada de revestimento necessária para atender as solicitações impostas aos pavimentos por meio dos métodos mecanísticos-empíricos. Para isto, foi então feito uso da contagem de veículos realizados para BR116, no entanto, foi necessário criar faixas de volume de tráfego (N), devido o método do DNIT não considerar o arranjo dos eixos que o SisPavBR e AASHTO fazem em suas avaliações. Foi realizado também o levantamento do custo executivo do km de pavimento dimensionado por cada método, e uma análise estatística foi realizada por meio da AASHTO com variações nas espessuras do revestimento, base, sub-base, módulos de resiliência da base, sub-base, subleito e o volume de tráfego, para determinar quais destas variáveis causam maior interferência nos critérios de desempenho. Desta maneira, verificou-se que o pavimento dimensionado pelo DNIT necessita de uma espessura de revestimento de 12,5 cm, o SisPavBR necessita de 19,5 cm e a AASHTO precisou de 40 cm, da mesma forma que o custo do pavimento foi mais elevado para o dimensionamento da AASHTO e o DNIT e SisPavBR tiveram custos mais próximos. A vida de projeto do pavimento do DNIT ficou bem abaixo do esperado em ambas as análises, chegando em um caso durar apenas 2 meses. A análise estatística determinou 5 equações para determinação dos mecanismos de deterioração com R² acima de 0,85; foi possível determinar que as principais variáveis que influenciam no desempenho dos pavimentos flexíveis são o volume de tráfego e a espessura do revestimento.