The Utah Department of Transportation (UDOT) has fully implemented the Mechanistic-Empirical Pavement Design Guide for pavement design but has been using primarily level-three design inputs obtained from correlations to aggregate base materials developed at the national level. UDOT was interested in investigating correlations between laboratory measurements of resilient modulus, California bearing ratio (CBR), and other material properties specific to base materials commonly used in Utah; therefore, a statewide testing program was needed. The objectives of this research were to 1) determine the resilient modulus of several representative aggregate base materials in Utah and 2) investigate correlations between laboratory measurements of resilient modulus, CBR, and other properties of the tested materials. Two aggregate base materials were obtained from each of the four UDOT regions. Important material properties, including particle-size distribution, soil classification, and the moisture-density relationship, were investigated for each of the sampled aggregate base materials. The CBR and resilient modulus of each aggregate base material were determined in general accordance with American Society for Testing and Materials D1883 and American Association of State Highway and Transportation Officials T 307, respectively. After all of the data were collected, several existing models were evaluated to determine if one or more of them could be used to predict the resilient modulus values measured in this research. Statistical analyses were also performed to investigate correlations between measurements of resilient modulus, CBR, and other properties of the tested aggregate base materials, mainly including aspects of the particle-size distributions and moisture-density relationships. A set of independent predictor variables was analyzed using both stepwise regression and best subset analysis to develop a model for predicting resilient modulus. After a suitable model was developed, it was analyzed to determine the sensitivity of the model coefficients to the individual data points. For the aggregate base materials tested in this research, the average resilient modulus varied from 16.0 to 25.6 ksi. Regarding the correlation between resilient modulus and CBR, the test results show that resilient modulus and CBR are not correlated for the materials tested in this research. Therefore, a new model was developed to predict the resilient modulus based on the percent passing the No. 200 sieve, particle diameter corresponding to 30 percent finer, optimum moisture content, maximum dry density (MDD), and ratio of dry density to MDD. Although the equation may not be applicable for values outside the ranges of the predictor variables used to develop it, it is expected to provide UDOT with reasonable estimates of resilient modulus values for aggregate base materials similar to those tested in this research.

No description available.

No description available.

This study focused on the material characterization of granular materials containing different percentages of “RAP”. A series of laboratory tests results were carried out to determine the physical and mechanical properties of natural aggregates and various aggregate-RAP blends. The results were used to evaluate methods to develop high-performance granular layer for pavement construction through proper compaction and control of RAP usage. The resilient modulus and accumulative deformation characteristics were determined in relation to RAP content, relative density, compaction method, stress level, stress state and the number of load applications. The effects of RAP content and density on the CBR values of aggregate-RAP blends under various conditions were also investigated. In addition, the effect of small strain cyclic loading on shear strength of aggregate-RAP blends was observed in laboratory tests. Results from this investigation demonstrated that: 1) adding RAP to natural aggregates may increase the resilient modulus of natural aggregates, and optimum content can be found to achieve the highest resilient modulus; 2) resilient modulus generally increases with density; higher density of aggregate-RAP blends can be achieved by using methods combining vibration and static loading. 3) deviatoric stress has more pronounced influence on accumulative deformation than confining pressure. 4) proper compaction method can reduce accumulative deformation of samples. 5) addition of RAP into aggregates results in little change in accumulative deformation when the RAP content is less than a threshold. 6) CBR value decreases with increasing RAP content and decreasing compaction effort or compacted dry density. 7) shear strength of an aggregate-RAP blend tends to increase after small strain cyclic loading. / Thesis / Master of Applied Science (MASc)

In the current mechanistic-empirical (M-E) design procedures for flexible pavements, the primary transfer functions are those that relate (a) maximum tensile strain in the hot-mix asphalt (HMA) surface layer to fatigue cracking and (b) compressive strain at the top of the subgrade layer to rutting at the surface. These functions, called fatigue and rutting equations, are usually derived from statistically based correlations of pavement condition with observed laboratory specimen performance, full-scale road test experiments or by both methods. Hot-mix asphalt fatigue behavior is an important component of a M-E design procedure; unfortunately, most of the existing models do not reflect field fatigue behavior. This is manifested in the fact that HMA fatigue failure is achieved much faster under a laboratory setting than in a field environment. This difference has been typically accounted for by the use of a single shift factor based mainly on engineering experience. The flexible pavement portion of the Virginia Smart Road includes 12 different flexible pavement designs. Each section is approximately 100m long. The sections are instrumented with pressure cells, strain gages, time-domain reflectometry probes, thermocouples, and frost probes. The instruments were embedded as layers were built. Laboratory fatigue tests of field cores and field-mixed laboratory-compacted specimens along with measured response from the instrumented pavement sections at the Virginia Smart Road were used to quantify the differences between laboratory and field environments. Four shift factors were identified to correlate field and lab fatigue behavior: stress-state, material difference, traffic wander, and healing. Field-measured critical strains and strain energy exerted during truck loading were both used to determine the stress state shift factor. Strain measurements of truck loading distribution (wander) were used to determine the wander shift factor. Finally, results from laboratory fatigue tests on cores and laboratory compacted specimens were used to evaluated a shift factor to account for the difference in compaction procedures. While the derived shift factors utilize the measured stresses and strains at the Virginia Smart Road, calculated strains and stresses, based on appropriate pavement and loading modeling, may also be used. / Ph. D.

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.

Esta pesquisa apresenta uma contribuição ao entendimento do efeito da variação do estado de tensões e variação de umidade na compactação, na suscetibilidade à deformação permanente dos solos de subleito. Assim, um programa experimental foi desenvolvido considerando as variáveis o estado de tensões e a umidade, que são importantes na análise da evolução da deformação permanente dos solos de subleito. Para esta avaliação, foi utilizado um solo arenoso laterítico proveniente da região de Dois Córregos, estado de São Paulo, Brasil. Foram realizados ensaios de caracterização e ensaios triaxiais de cargas repetidas (módulo de resiliência e deformação permanente). Adicionalmente, foi analisado o efeito do acúmulo de deformação permanente nos valores de módulo de resiliência, que foi efetuado a partir de ensaios realizados antes e após o ensaio de deformação permanente. Além disso, de posse dos resultados de deformação permanente foi verificada a ocorrência do Shakedown. Concluiu-se que um aumento de tensões causa um aumento na deformação permanente, não sendo possível avaliar o efeito da variação de umidade na deformação permanente. Observou-se a ocorrência do Shakedown, porém não foi possível definir seu limite. Não foi possível o enquadramento da deformação permanente no modelo de Monismith, sendo proposto, por meio de regressão múltipla, um modelo para avaliação da deformação permanente, considerando as variáveis, umidade, número de aplicações de carga e estado de tensões. / This research presents a contribution to understanding the effect of the variation of the state of stress and water content in the evolution of the permanent deformation of subgrade soils. A lateritic sandy soil from the region of Dois Córregos, State of São Paulo, Brazil, was used throughout the characterization and triaxial repeated loads tests (resilient module and permanent deformation tests). Additionally, it was analyzed the effect of the accumulation of permanent deformation in the values of resilient module from tests performed before and after the permanent deformation tests, as well as it was verified the occurrence of Shakedown. It was concluded that an increase of stress causes an increase in permanent deformation, but it was not possible to evaluate the effect of the variation of moisture content in permanent deformation. It was also observed the occurrence of Shakedown, but it was not possible to set its limit. Furthermore, it was not possible to fit the permanent deformation testing data in the model of Monismith, being proposed, by means of multiple regression, a model for the assessment of permanent deformation considering the variables moisture content, number of load applications and state of stress.

Um dos maiores problemas do setor da fundição de metais é a produção de resíduos sólidos, constituídos basicamente pelas areias residuais. Geralmente, o uso de aditivos e ligantes no processo de fundição limita a reutilização da areia, o que obriga as indústrias a destinar esse resíduo a depósitos de descarte, apesar da boa qualidade que a areia apresenta para outros usos, principalmente na engenharia civil. No Brasil, a produção de fundidos em 2006 alcançou três milhões de toneladas, com a geração de, aproximadamente, uma tonelada de resíduo para cada tonelada de metal produzida. Nesse sentido, procuram-se alternativas para reutilizar a areia de fundição em grandes quantidades, que permitam reduzir os custos de descarte pelas siderúrgicas e a utilização na construção de pavimentos fornece oportunidades para o reuso nas diferentes camadas estruturais. O objetivo deste trabalho é avaliar o reaproveitamento da areia de fundição como material de construção em sub-bases e bases de rodovias, através de sua incorporação a solos argilosos lateríticos da região de Sertãozinho/SP, que tem grande produção de fundidos e, conseqüentemente, de resíduos e também carece de jazidas de solos arenosos para a construção de rodovias e vias urbanas. No estudo foi utilizada a técnica de montagem de solos artificiais a partir de dois solos lateríticos argilosos e do resíduo areia de fundição e da areia virgem. Os solos artificiais foram submetidos aos ensaios de: limite de liquidez e plasticidade, granulometria por peneiramento e sedimentação, mini-MCV, perda de massa por imersão, mini-CBR, expansão, contração, infiltrabilidade e permeabilidade em corpos-de-prova de dimensões reduzidas e na energia intermediária, CBR na energia intermediária e triaxial dinâmico. Para determinar a periculosidade do resíduo foram executados ensaios ambientais de massa bruta, lixiviação e solubilização. A partir dos resultados obtidos nestes ensaios foi possível analisar a variação das propriedades tecnológicas e ambientais dos solos em função do teor de areia de fundição adicionada. Os solos lateríticos argilosos com 60% de areia de fundição adicionada apresentaram propriedades mecânicas que atendem as especificações do DER-SP (1991) e do Manual de Pavimentação do DNIT (2006). Os ensaios ambientais mostraram que a areia de fundição, utilizada nesta pesquisa, apresenta características que se enquadram dentro dos parâmetros da CETESB, o que permite que o resíduo seja avaliado para seu reaproveitamento na construção de rodovias. Com base na análise dos resultados conclui-se que o resíduo areia de fundição é de uso promissor nas camadas de base e sub-base de rodovias de baixo volume de tráfego. / One of the biggest problems of the foundry industry is the solid residues production, constituted basically by sands. The use of additives and binders in the foundry process reduces the reuse of the sand and the remainder is discarded in industrial landfills or stockpiled on site, although the good quality of the sand as aggregate for manufactured products such as Portland cement, asphalts and geotechnical applications such as road bases, structural fills, embankments and manufactured soils. The foundry production, in year 2007, in Brazil, exceeded three millions tons, and it is had that for each ton of produced metal, a ton of foundry residue results approximately. The long term sustainability, economics and reuse practices suggest that alternative use practices must be done for the foundry sand and the roadways construction supply such opportunities. The purpose of this work is to evaluate the reuse of foundry sand as a construction material for road bases and sub-bases, trough its incorporation to clay lateritic soils from Sertaozinho, Sao Paulo state region. This region has a highly production of foundry metals and residues, and does not have natural sandy soils deposits for the construction of highways and urban roads. The technique used in this study was de soil assembly; foundry sand and virgin sand were mixed with two clay lateritic soils in different proportions. Tests were made in the soil-sand mixes to evaluate the sand addition influence in the mechanic soil behaviour, which are: liquid limit and plastic limit, granulometry, mini-MCV, immersion lost mass, mini-CBR at the intermediate energy, expansion, contraction, CBR at the intermediate energy, infiltrability, permeability and dynamic triaxial. Also, environment tests - leaching and solubility - were made to establish the hazard of the foundry sand. The results show that lateritic clay soils with 60% of foundry sand added has adequate mechanical properties to be used as base and sub-base material for low traffic pavements, according to the DER-SP(1991) specifications and the DNIT Manual Pavement (2006). The environment tests indicate that the foundry sand residue, used in this work, has promising use in road bases and sub-bases.

In the mechanistic design approach, which has already been started to utilize in several countries, the variations in material properties are better taken into account based on fundemental engineering principles. Resilient modulus is the most important material property that is used in the mechanistic design since it describes the true martial performance of unbound pavement layers under traffic loading. In this thesis, the objective is to determine the resilient modulus, used in the mechanistic design of pavement structures, for the unbound material types used in Turkey and develop linear and nonlinear prediction models to determine resilient response of unbound layers based on soil index properties, California Bearing Ratio (CBR) and Light Falling Weight Deflectometer (LFWD) test results. Application of genetic algorithm and curve shifting methodology to estimate design resilient modulus at various stress states is also investigated using the test results for finegrained soils. Resilient modulus estimation for a constant stress state based on genetic algorithm and curve shifting methodolgy is quite promising for fine-grained soils since nonlinear constitutive models do not have the capability of representing resilient responses under different conditions. Furthermore, tree-based modeling is discussed as an alternative way to develop resilient modulus prediction models. The outcome of the study will be a basis for the performance based design specifications of flexible pavements.

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.