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

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

O trabalho apresenta o programa interlaboratorial de agregados e de misturas asfÃlticas da REDE ASFALTO N/NE, um arranjo de nove instituiÃÃes brasileiras coordenado pela Universidade Federal do Cearà (UFC). O objetivo do trabalho à a implantaÃÃo de um programa interlaboratorial para caracterizaÃÃo de agregados e dosagem de misturas asfÃlticas dentro da REDE e a utilizaÃÃo dos resultados como ferramenta para uniformizar os procedimentos dos laboratÃrios participantes. Foram distribuÃdas pela UFC amostras de agregados e de ligante asfÃltico para realizaÃÃo de ensaios por parte dos laboratÃrios. Os agregados foram caracterizados com relaÃÃo à densidade, absorÃÃo, Ãndice de forma, abrasÃo Los Angeles e equivalente de areia. Para a dosagem Marshall, utilizaram-se os resultados obtidos pelos laboratÃrios na fase do interlaboratorial de agregados. TambÃm foram distribuÃdas cinco amostras de mistura asfÃltica solta para cada laboratÃrio, que ficaram responsÃveis pelo reaquecimento, compactaÃÃo e pesagem das mesmas. Em seguida, estas amostras compactadas foram devolvidas à UFC para nova pesagem, para fins de comparaÃÃo. Os resultados foram analisados por meio dos mÃtodos estatÃsticos da Elipse de ConfianÃa, do z-score e dos testes de Dixon e de Cochran. Observou-se que o teor Ãtimo de ligante determinado a partir da metodologia Marshall oscilou entre 4,5% e 8,0%, para uma mesma mistura testada em diferentes laboratÃrios. Os erros mais freqÃentes detectados nos diversos ensaios estÃo relacionados aos cÃlculos, à descalibraÃÃo da balanÃa e/ou à falta de entendimento das normas tÃcnicas. TambÃm à apresentada uma verificaÃÃo da distribuiÃÃo Normal para os ensaios de: densidade aparente, densidade real e absorÃÃo do agregado graÃdo, densidade aparente e Vv de CP. O programa contribuiu para a realizaÃÃo de ensaios com maior confiabilidade e credibilidade, alÃm de promover uma melhor integraÃÃo entre os grupos envolvidos. / This thesis presents the interlaboratory program for aggregates and asphalt mixture characterizations within the Brazilian NORTH-NORTHEAST ASPHALT NETWORK, an arrangement of nine institutions leaded by Universidade Federal do Cearà (UFC). The main focus of this work is to contribute for the laboratories staff professional development and to improve the testing procedures accuracy. Asphalt binder and different aggregates samples were distributed for the nine institutions to perform the aggregates characterization tests and the asphalt mixture design following the Marshall procedure. The aggregates were characterized with respect to: (i) density, (ii) absorption, (iii) shape index, (iv) Los Angeles abrasion, and (v) sand equivalent. For the Marshall design, the results obtained for the aggregates characterization were used. Moreover, five samples of loose asphalt mixture were distributed for each laboratory, where they were reheated, compacted and weighed for air voids content determination. These samples were returned to UFC with the purpose of being reevaluated in terms of its volumetric parameters determination. The results were analyzed using different statistical methods such as: (i) ellipse of confidence, (ii) z-score and (iii) tests of Dixon and Cochran. It was observed that there was a variation between 4.5 to 8.0% in the optimum asphalt binder content determination when the same mixture was designed in different laboratories. The most frequent errors found in the various tests are related to: (i) calculations procedures, (ii) equipment calibration and/or (iii) lack of understanding of the technical standards. The program contributed to improve the tests reliability and credibility, and to promote a greater integration between the involved groups.

<p><a>Voids in the mineral aggregate (VMA), as a main volumetric design parameter in the Superpave mixture design method, is an important factor to ensure asphalt mixture durability and rutting performance. Moreover, an asphalt mixture’s aggregate skeleton, related to VMA, is another important factor that affects critical asphalt mixture properties such as durability, workability, permeability, rutting, and cracking resistance. The objective of this study is to evaluate the effects of aggregate size distribution and shape parameters on aggregate packing characteristics (volumetric and compaction properties) of asphalt mixtures. Three tasks were undertaken to reach this goal. </a></p> <p>The first task was to propose an analytical approach for estimating changes in voids in the mineral aggregate (VMA) due to gradation variation and determining the relevant aggregate skeleton characteristics of asphalt mixtures using the linear-mixture packing model, an analytical packing model that considers the mechanisms of particle packing, filling and occupation. Application of the linear-mixture packing model to estimate the VMA of asphalt mixtures showed there is a high correlation between laboratory measured and model estimated values. Additionally, the model defined a new variable, the central particle size of asphalt mixtures that characterized an asphalt mixture’s aggregate skeleton. Finally, the proposed analytical model showed a significant potential to be used in the early stages of asphalt mixture design to determine the effect of aggregate gradation changes on VMA and to predict mixture rutting performance.</p> <p>As the second task, a framework to define and understand the aggregate structure of asphalt mixtures was proposed. To develop this framework, an analytical model for binary mixtures was proposed. The model considers the effect of size ratio and air volume between the particles on the aggregate structure and packing density of binary mixtures. Based on this model, four aggregate structures, namely coarse pack (CP), coarse-dense pack (CDP), fine-dense pack (FDP) and fine pack (FP), were defined. The model was validated using a series of 3D discrete element simulation. Furthermore, the simulation of multi-sized aggregate blends using two representative sizes for fine and coarse stockpiles was carried out to apply the proposed analytical model to actual aggregate blends. The numerical simulations verified the proposed analytical model could satisfactorily determine the particle structure of binary and multi-sized asphalt mixture gradations and could, therefore, be used to better design asphalt mixtures for improved performance. </p> <p>The third task virtually investigated the effect of shape characteristics of coarse aggregates on the compactability of asphalt mixtures using a discreet element method (DEM). The 3D particles were constructed using a method based on discrete random fields’ theory and spherical harmonic and their size distribution in the container was controlled by applying a constrained Voronoi tessellation (CVT) method. The effect of fine aggregates and asphalt binder was considered by constitutive Burger’s interaction model between coarse particles. Five aggregate shape descriptors including flatness, elongation, roundness, sphericity and regularity and, two Superpave gyratory compactor (SGC) parameters (initial density at N_ini and compaction slope) were selected for investigation and statistical analyses. Results revealed that there is a statistically significant correlation between flatness, elongation, roundness, and sphericity as shape descriptors and initial density as compaction parameter. Also, the results showed that the maximum percentage of change in initial density is 5% and 18% for crushed and natural sands, respectively. The results of analysis discovered that among all particle shape descriptors, only roundness and regularity had a statistically significant relation with compaction slope, and as the amount of roundness and regularity increase (low angularity), the compaction slope decreases. Additionally, the effect of flat and elongated (F&E) particles percentage in a mixture using a set of simulations with five types of F&E particles (dimensional ratios 1:2, 1:3, 1:4 and 1:5) and ten different percentage (0, 5, 10, 15, 20, 30, 40, 50, 80 and 100) with respect to a reference mixture containing particles with flatness and elongation equal to 0.88 was conducted. Results indicated that increase of F&E particles in a mixture (more than 15%) results in a significant reduction in the initial density of the mixture especially for lower dimensional ratio (1:4 and 1:5). <b><i></i></b></p> <br> <p> </p>

No description available.

The diploma thesis is focused on the comparison of the influence coarse-grained aggragate on the properties af asphalt concrete. The theoretical part describes issue of production and usage of asphalt mixtures. The practical part evaluates multiple types of asphalt mixtures and describing their properties. Stiffness by a two-point bending test, a wheel tracking test and low-temperature cracking and properties by uniaxial tension test were used to evaluate the properties of the mixtures.

Os procedimentos de dosagem Marshall e Superpave definem os teores de ligante de projeto baseados em parâmetros volumétricos. Nessa situação, sistemáticas de dosagem com tipos de compactação diferentes podem conduzir a teores de ligante de projeto distintos que definirão a vida útil dos revestimentos asfálticos. O objetivo principal desse trabalho é avaliar o comportamento mecânico de misturas asfálticas moldadas por diferentes métodos de compactação de laboratório e analisar a relação com os resultados de amostras obtidas a partir de misturas compactadas por rolagem pneumática na mesa compactadora francesa. A fase experimental consistiu na dosagem de misturas pelos métodos Marshall e Superpave (este último com dois tamanhos de moldes), além da compactação na Prensa de Cisalhamento Giratória (PCG) e da moldagem de placas na mesa compactadora. Avaliou-se o efeito do tipo de compactação, do tamanho do molde e do número de giros do Compactador Giratório Superpave (CGS) no teor de projeto, nos parâmetros volumétricos, no comportamento mecânico e no desempenho quanto à fadiga e à resistência ao afundamento em trilha de roda. Adicionalmente, foi avaliada a eficiência do método Bailey de composição granulométrica quanto à resistência à deformação permanente em função do tipo de agregado. Constatou-se que o método Bailey, por si só, não garante resistência à deformação permanente, sendo essa dependente do tipo de agregado incluindo seus parâmetros de forma. O principal produto da pesquisa, com efeitos práticos no projeto de misturas asfálticas, traduz-se na recomendação do método Superpave com molde de 100 mm (para TMN <= 12,5 mm) para volume de tráfego médio a alto em detrimento ao método Superpave com 150 mm, tendo em vista que o primeiro apresenta densificação mais semelhante às amostras preparadas na compactação por rolagem (similar ao que ocorre em pista) o que resulta em comportamento mecânico também mais próximo da realidade de campo. A utilização dos moldes de 150 mm de diâmetro no CGS pode ser viabilizada desde que se adote um número de giros menor do aquele proposto para projeto pelo Asphalt Institute (2001). Por fim, é fundamental que os ensaios e os cálculos para obtenção dos parâmetros volumétricos e escolha do teor de projeto sigam ao normatizado pela ASTM, pelo Asphalt Institute (2001) e pela ABNT. / The Marshall and Superpave mixture designs procedures are based mainly on volumetric parameters. Despite this similarity, the definition of the optimum asphalt content is highly influenced by the laboratory compaction method. The main objective of this study is to evaluate the effect of the compaction method on the volumetric and mechanical properties of asphalt mixtures. Furthermore, the results are compared with the performance of samples prepared on the LCPC roller compactor. The experimental procedure included Marshall and Superpave mixture design methods (the second one with two mold sizes), the French gyratory shear compactor (PCG), and also the LCPC roller compactor. The effect of compaction method, mold size and number of gyrations on the air voids content (and consequently, on the optimum asphalt binder content), mechanical properties and on the fatigue and rutting performance were evaluated. Moreover, the efficiency of the Bailey method for aggregate gradation selection on rutting was evaluated by the wheel tracking test of the LCPC. It was found that the Bailey method itself does not ensure resistance to rutting. It depends on the aggregate source, specially its shape. The main contribution of this study is the recommendation of the Superpave 100 mm (NMS <= 12,5 mm) for medium and high traffic, once its densification was similar to the roller compacted samples. The use of 150 mm molds in the SGC is recommended only if the number of gyrations is smaller than the one used in this study. It is essential that the laboratory standard procedures used for the tests and volumetric parameters calculations follow ASTM, Asphalt Institute (2001) and ABNT.

Este trabalho tem como objetivo avaliar o comportamento à fadiga de algumas misturas asfálticas, à luz de resultados de ensaios de fadiga por compressão diametral à tensão controlada, realizados em corpos-de-prova, considerando-se a variação de dois fatores: tipo de asfalto e volume de vazios. Para mesmo agregado (basáltico) e mesma faixa granulométrica (centro da faixa C do DNER) foram moldados, segundo os procedimentos do método Marshall, corpos-de-prova com três tipos de ligantes, sendo um asfalto convencional (CAP 20), um asfalto modificado com polímero (CAP 20 + SBS) e um asfalto modificado com borracha reciclada de pneus (CAP + BRP), em três diferentes volumes de vazios 3, 4 e 5%. São apresentados resultados dos ensaios de resistência à tração por compressão diametral, módulo de resiliência e de fadiga. Os modelos de fadiga são apresentados em função das diferenças de tensões e de deformações. Para avaliar o desempenho relativo das misturas, foram simuladas estruturas de pavimentos, dimensionadas pelo método do DNER, para as quais foram determinadas as tensões e deformações atuantes que, por sua vez, foram utilizadas nos modelos de fadiga com a finalidade de determinar as vidas de fadiga. Os resultados indicam que, para maioria dos casos estudados, as misturas com o CAP 20 + SBS apresentaram melhor desempenho (maior vida de fadiga), seguidas pelas com CAP 20 + BRP e, por último, pelas com CAP 20 / The purpose of this research is to evaluate the fatigue behavior of some asphalt mixtures, by means of indirect tensile tests with controlled stress. In order to evaluate different asphalt mixtures, it was molded specimens according to Marshall design method, considering the variation of two factors: asphalt type and air voids. Asphalt concrete specimens were molded with three types of asphalt (conventional, polymer modified and asphalt rubber) and three air void content (3, 4 and 5%), with the same aggregate (basaltic) and same gradation (center of DNER C gradation). Test results of indirect tensile strength, resilient modulus and fatigue are presented. The fatigue models are constructed in function of the differences of stress and strain. The fatigue behavior of asphalt mixtures was evaluated based on pavement structures (designed according to DNER standards) and stresses and strains estimated with aid of ELSYM5 program. The results indicated that, for almost all studied cases, mixtures with polymer modified asphalt (CAP 20 + SBS) had presented fatigue life higher than the other ones, followed by the ones with asphalt rubber (CAP 20 + BRP) and with conventional asphalt (CAP 20)

Este trabalho tem como objetivo avaliar o comportamento à fadiga de algumas misturas asfálticas, à luz de resultados de ensaios de fadiga por compressão diametral à tensão controlada, realizados em corpos-de-prova, considerando-se a variação de dois fatores: tipo de asfalto e volume de vazios. Para mesmo agregado (basáltico) e mesma faixa granulométrica (centro da faixa C do DNER) foram moldados, segundo os procedimentos do método Marshall, corpos-de-prova com três tipos de ligantes, sendo um asfalto convencional (CAP 20), um asfalto modificado com polímero (CAP 20 + SBS) e um asfalto modificado com borracha reciclada de pneus (CAP + BRP), em três diferentes volumes de vazios 3, 4 e 5%. São apresentados resultados dos ensaios de resistência à tração por compressão diametral, módulo de resiliência e de fadiga. Os modelos de fadiga são apresentados em função das diferenças de tensões e de deformações. Para avaliar o desempenho relativo das misturas, foram simuladas estruturas de pavimentos, dimensionadas pelo método do DNER, para as quais foram determinadas as tensões e deformações atuantes que, por sua vez, foram utilizadas nos modelos de fadiga com a finalidade de determinar as vidas de fadiga. Os resultados indicam que, para maioria dos casos estudados, as misturas com o CAP 20 + SBS apresentaram melhor desempenho (maior vida de fadiga), seguidas pelas com CAP 20 + BRP e, por último, pelas com CAP 20 / The purpose of this research is to evaluate the fatigue behavior of some asphalt mixtures, by means of indirect tensile tests with controlled stress. In order to evaluate different asphalt mixtures, it was molded specimens according to Marshall design method, considering the variation of two factors: asphalt type and air voids. Asphalt concrete specimens were molded with three types of asphalt (conventional, polymer modified and asphalt rubber) and three air void content (3, 4 and 5%), with the same aggregate (basaltic) and same gradation (center of DNER C gradation). Test results of indirect tensile strength, resilient modulus and fatigue are presented. The fatigue models are constructed in function of the differences of stress and strain. The fatigue behavior of asphalt mixtures was evaluated based on pavement structures (designed according to DNER standards) and stresses and strains estimated with aid of ELSYM5 program. The results indicated that, for almost all studied cases, mixtures with polymer modified asphalt (CAP 20 + SBS) had presented fatigue life higher than the other ones, followed by the ones with asphalt rubber (CAP 20 + BRP) and with conventional asphalt (CAP 20)

Loaded wheel tester (LWT) is a common testing equipment usually used to test the permanent deformation and moisture susceptibility of asphalt mixtures by applying moving wheel loads on asphalt mixture specimens. It has been widely used in the United States since 1980s and practically each Department of Transportation or highway agency owns one or more LWT(s). Compared to other testing methods for pavement materials, LWT features movable wheel loads that allow more realistic situations existing on the actual pavement to be simulated in the laboratory. Due to its potential of creating a condition of repetitive loading, the concept of using LWT for characterizing the properties of pavement materials were promoted through four innovative or modified tests in this study. (1) The first test focuses on evaluating the effect of geogrids in reinforcing pavement base courses. In this test, a base course specimen compacted in a testing box with or without geogrids reinforced was tested under cyclic loading provided by LWT. The results showed that LWT test was able to characterize the improvement of the pavement base courses with geogrids reinforcement. In addition, the results from this study were repeatable and generally in agreement with the results from another independent study conducted by the University of Kansas with similar testing method and base materials. (2) A simple and efficient abrasion test was developed for characterizing the abrasion resistance of pervious concrete utilizing LWT. According to the abrading mechanisms for pervious concrete, some modifications were made to the loading system of LWT to achieve better simulations of the spalling/raveling actions on pervious concrete pavements. By comparing the results from LWT abrasion tests to Cantabro abrasion tests, LWT abrasion test was proved effective to differentiate the abrasion resistances for various pervious concretes. (3) Two innovative LWT tests were developed for characterizing the viscoelastic and fatigue properties of asphalt mixtures in this study. In the test, asphalt beam specimens are subjected to the cyclic loads supplied by the moving wheels of LWT, and the tensile deformations of the beam specimens are measured by the LVDTs mounted on the bottom. According to the stress and strain, the parameters associated to the viscoelastic and fatigue properties of the asphalt mixture can be obtained through theoretical analyses. In order to validate the concepts associated with the above mentioned tests, corresponding conventional tests have also been conducted to the same materials in the study. According to the comparisons between the conventional and the LWT tests, the LWT tests proposed in this study provided satisfactory repeatability and efficiency.