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6th International Conference on Accelerated Pavement Testing , NANTES, FRANCE, 27-/09/2021 - 29/09/2021; The concept of truck platooning is to take advantage of the connectivity technologies and automated driving support systems to link trucks in close formation (convoy) in order to increase transport efficiency, reduce fuel consumption and gas emissions while improving road safety. However, closely guided trucks following each other could have a different impact on road structures than the usual truck traffic. Notably, different studies with traffic simulators highlight the significant effect of the wander pattern of traffic on the damage observed on test road structures. On the other hand, the positioning systems could offer the opportunity to choose an optimized wander pattern of the trucks within the platoons, especially designed to mitigate the overall damage. In this context, the study reported in this paper addresses, through numerical simulations, the multi-loading effects of truck platoons on road structures for different configurations of wander patterns. The aggressiveness of these patterns is evaluated on the basis of the viscoelastic response of the pavement structures (strain field) computed using software ViscoRoute\textcopyright 2.0. Finally, recommendations on the choice of wander pattern configurations to be tested on APT facilities are proposed.

Dynamic on-road charging of vehicles can be done by conductive means, whose implementation require the presence of elements in the pavement, potentially affecting its durability. Some prototypes tested on site and in laboratory showed different mechanisms of damage: rutting, interface debonding and thermal cracking. Including different materials in an asphalt concrete (AC) can generate differential stress fields that can lead to premature failure. A thermal test was developed to simulate the behaviour of AC under daily thermal solicitations. This paper focuses on the development of a numerical simulation able to represent the stress field evolution in the AC. A Generalized Maxwell model coupled to WLF equation represented the thermo-viscoelastic behaviour of the AC under such conditions. This model was implemented into a FEM software named Cast3m®. First results show a stress concentration in the AC just under the groove. According to the design used for implementing ERS infrastructures, stress levels remain under acceptable values as to avoid damage.

Nowadays, the development of electric heavy goods vehicles is hindered by the limited capacity of batteries. An alternative solution to batteries is to develop electrified road systems, capable of supplying and/or recharging electric vehicles while they are driving. In this project, an Electric Road System (ERS), i.e. a solution for electric supply by a feeding track embedded in the pavement, is studied. The system consists of metallic conductive segments, fixed on a rubber support, installed in a groove in the middle of the pavement. Laying such a device in a bituminous pavement requires an efficient bonding of the rubber with the pavement materials, and a good resistance to traffic and climate. Studies were made at laboratory scale and at full scale to select appropriate joint materials and assess the load resistance and durability of the rail/pavement system. Two types of laboratory tests were performed on asphalt concrete samples integrating the rubber elements: wheel tracking tests, at temperatures of 20, 40 and 60 °C, and climatic tests (temperature cycles between −20 °C and 20 °C). Modelling of the tests was also carried out. After evaluation of different products, an appropriate joint material was selected. Then, an accelerated test was performed with the FABAC traffic simulator, to validate the behavior of the electric supply system inserted in a bituminous pavement, at full scale. The pavement structure was instrumented, submitted to 500 000 dual wheel load cycles at 65 kN, and monitored using deflection measurements and profile measurements. The test confirmed the satisfactory behavior obtained at laboratory scale.

International audience; With the depletion of the virgin aggregates, many efforts have been oriented towards the recycling of the reclaimed asphalt pavement (RAP). However, quality control of the recycled product is required during the manufacture process. This research deals with the use of high-content RAP recycled asphalt mixture composed of 70% RAP based on experimental and micromechanical approaches. For the experimental part, a "Good" and a "Bad" blended mixture were manufactured in laboratory. Then, rheological measurements of the complex modulus of the different binders and mixtures were carried out. The micromechanical work is based on the generalised self-consistent scheme (GSCS) which was used to predict the mechanical properties of the recycled mixture. This approach aims to homogenize the heterogeneous material by taking into account both the intergranular porosity and the possible interactions between phases. The confrontation of the micromechanical model with the experimental results showed good agreements between measured data and predicted values of the complex modulus of the recycled asphalt. Moreover, it was highlighted from the experimental results that the blending process of the recycled mixture has a great influence on the viscoelastic properties of the recycled mixture. This result was also validated by the GSCS-based approach.

Recycling of old pavements is becoming a widespread technique; in order to preserve the natural resources of aggregates and binder, the materials reclaimed from the damaged layers of the pavements maintained are generally reincorporated in the material for new maintenance layers. However, recycling induces some technical challenges. In the case of the Hot mix asphalt (HMA), the most commonly used road construction material, one of the main concerns is ageing. Along with the heterogeneity of the RA properties in stockpiles, it is one of the main factors limiting the recycling rates in HMA. Therefore, the characterisation of ageing through reliable ageing indexes and of its impact on the bitumen physical properties is of paramount importance to improve the recycling techniques. The RILEM TC 237 SIB TG5 inherited a database from the previous work of the RILEM TC 206 ATB TG5 on a protocol for bituminous mixture ageing in laboratory. Taking advantage of these data, the work of the Task Group was first dedicated to a state of the art and an evaluation of the chemical ageing characterization through indexes based on Fourier Transform Infrared Spectroscopy (FTIR). In a second step, an attempt was made, in order to bring out the essential trends of the rheological data with ageing, by using a Huet modified rheological model. Then, exploring the potential of a recently developed method, an interpretation of these trends in terms of asphalt structure is suggested. Finally, possible empirical relationships between the chemical ageing indexes and the rheological parameters are investigated.

This work aims to develop asphalt mixes with 100% reclaimed asphalt pavements (RAP) as source of aggregates and bitumen emulsions stabilized by amine-functionalized lignin. To that end, reduced-temperature asphalt technologies between 80 and 130 °C were assessed. Previously, processing parameters of emulsions were evaluated by droplet size distribution and rheology measurements. Furthermore, a study combining Pendant drop and Sessile drop (on a prototype polyethylene surface) tests showed that emulsion aqueous phase containing modified lignin would be able to wet the hydrophobic surface of RAP. Manufactured asphalt mixes were characterized according to French design method for hot mixes, including gyratory compaction, rutting resistance, complex modulus and fatigue resistance tests. The results obtained showed that reduced-temperature asphalt mixes could be successfully prepared to meet French design requirements, which would further minimize impact to environment. However, mix design has required a semi-quantitative approach for estimating ‘active’ RAP binder content, by balancing the manufacturing temperature and the fresh bitumen required.

Within the framework of a sustainable development, manufacturing bituminous mixtures while reducing energy and using less new aggregates and new bitumen may be considered as an important topic, according to the quantities of asphalts mixtures produced for creating and maintaining road networks. This work aims to study the interest and the potential problems when coupling the warm mix asphalt technology (WMA) and the use of high ratio of reclaimed asphalt pavement (RAP) in the mixture. Initially, a study on managing RAP is performed, aiming to show that separating RAP aggregates in several fractions leads to a higher control of RAP in terms of homogeneity. Homogeneity of RAP is a key point for increasing recycling rates. The present study coupling WMA and RAP is based on the French design method for manufacturing asphalt concretes, which includes gyratory compaction tests, French wheel tracking tests, complex modulus tests and fatigue tests. However, the French design method does not take into account the physical and chemical aging of bituminous mixtures with time. As we consider that coupling WMA and RAP may lead to aging problems, it was decided to use an aging process before performing the standard tests. The results show that a WMA containing a high ratio of RAP has good performances according to the standard relative to this material, whatever the test. However, this material tends to be more sensitive to fatigue than hot and warm mixes without RAP.

Sustainable development policies currently in effect in civil engineering serve to promote techniques capable of saving both energy and raw materials; such techniques use a combination of warm mix asphalt (WMA) concretes with reclaimed asphalt pavement (RAP). One issue raised when combining WMA and RAP involves determining the potential lack of RAP binder remobilisation during blending with the new binder, i.e. the so-called double-coating phenomenon. This paper aims to present the results of an Attenuated Total Reflection (ATR) imaging by means of infrared microspectrometry on asphalt mixtures featuring high RAP content. In the context of a Ph.D. thesis program, this analysis is combined with a study of the mechanical performance of these materials (not presented herein). The main objective of this research work is to assess the blending and coating quality of the materials at the microscopic scale. The experimental program consists of evaluating raw aggregates, binders, RAP and asphalt mixtures by ATR-FTIR microspectrometry in order to generate pictures for analysis and interpretation according to two distinct methods, namely Principal Component Analysis (PCA) and Independent Component Analysis (ICA). This analysis protocol introduces markers inside asphalts, like SBS or EVA copolymers or carbonyl and sulfoxide indices. The first main result of this study is improved control over the ATR imaging tool and its enhanced potential for analysing bituminous mixtures. A protocol for preparing samples and interpreting their results can now be proposed; an actual asphalt concrete has been analysed, not merely a laboratory-produced sample, as indicated in the literature. As a second result, tracers have been set up to distinguish raw and RAP materials (aggregates and binders), thus representing an initial step to studying the double coating, although it would seem difficult to generalise this study to a wide array of mixtures. Lastly, let’s point out that ATR-FTIR imaging is a “localised” study, making the determination of bituminous material homogeneity at specimen or even stockpile scale a real challenge for the future.

Within the framework of the European Project SUP&R ITN a PhD the-sis is carried out to study the durability of the combination of high rates of re-claimed asphalt pavement and warm mix asphalt technologies. For this purpose the complex modulus and fatigue resistance of three different asphalt mixtures, in-cluding surfactant modified and foamed warm mix asphalts, combined with re-claimed asphalt pavement (RAP) has been studied. The extra value is given by the application of an ageing procedure based on the oxidation of compacted materials in laboratory. It follows the recommendations of the RILEM TC-ATB TG5, which distinguishes between short and long term ageing. Fourier Transform InfraRed (FTIR) tests were carried out on the extracted bitumens to quantify the oxidation levels. An increase of the norm and a decrease of the phase angle of |E*| at 15°C 10Hz with ageing and RAP addition are experienced for all the mixtures. Similar to what happens with the slopes of the fatigue laws that tend as well to increase. A consistent correlation is observed between these evolutions and the evolution of the carbonyl index calculated. This reflects a trend towards more brittle materials with predicted fatigue live improved for low strain levels but reduced for high strain levels. In general, the tendency is similar for all procedures, so the use of warm technologies combined with high RAP amounts may need to be considered.

In order to study the permanent deformations of bituminous mixtures, a temperature-controlled triaxial test has been set up. By means of triaxial creep tests at imposed stress, the influence of different parameters on the behaviour of bituminous materials (confining pressure, deviatoric stress and temperature) has been investigated. A viscoelastic–viscoplastic model has been developed to simulate the creep tests and has shown good ability for simulating the test results.

25eme Congrès mondial de la route, SEOUL, COREE, REPUBLIQUE DE, 02-/11/2015 - 06/11/2015; Road mix asphalt manufacture process is associated with high consumption of raw materials, energy and high levels of emissions. The combined use of reclaimed asphalt and temperature reduction technologies may favour a cleaner and more sustainable production of asphalt mixtures. The aim of the present work is to study and compare two types of warm mix asphalts under two different technologies, surfactants and foamed asphalt, when adding high rates (50%) of reclaimed asphalt pavement into the mixtures. The study is based on the comparison of the mechanical performance of twelve mixtures through the fatigue and complex modulus tests. An aging procedure, based on the oxidation of materials in laboratory before testing, is developed. The aging protocol follows the lines proposed by the RILEM TC-ATB TG5 consisting in two separate aging phases. Penetration and ring and ball tests, as well as FTIR spectra were applied to know more about the evolution of aging from the bitumen extracted. Results show a relation between ageing evolution and mechanical performance. The ageing experienced by warm mix asphalt techniques is lower than conventional mixtures; however on fatigue life the performances are slightly different between them

Setting a method to evaluate the mechanical properties of an aged asphalt mix using a rapid chemical measurement from small samples, would be of high interest at different steps of a road structure life cycle: at the design step, to optimise the estimates of the service lifetime usually based on the properties of unaged materials; during the service life, to update the residual lifetime expectation of an existing structure according to the actual properties of the in situ aged materials; and at the end of the service life or for maintenance management, to evaluate the recyclability of the materials of the structure. This study was carried out aiming at comparing results from Fourier Transform InfraRed and Dynamic Shear Rheometer tests. Experimental data came from an international round robin test, organised by the RILEM TC ATB, designed to set an ageing protocol on loose bituminous mixtures. The evolutions of the carbonyl index (ICO) calculated from the FTIR spectra are compared to the evolutions of the parameters of a modified Huet Rheological Model (1S2P1D) fitted on the experimental linear viscoelastic data measured on the recovered binder. A significant relationship is observed suggesting that chemical and rheological properties could be correlated. Based on this observation, a method is proposed for predicting the G* values of a binder aged at a given ΔICO level. Subsequently, this method could be used to predict the complex modulus E* of a given mix from the shear modulus G* of the binder using existing binder/mix transfer models.

In the framework of a study on rutting of bituminous layers, thermo-controlled triaxial tests under constant confining pressure on homogeneous asphalt concrete specimen have been performed. These tests are cyclic sinusoidal tests, with the aim to reproduce in some way the loading and unloading phases due to traffic on roads. The influences of confinement and load frequency have been studied. Tests have highlighted that confinement notably decreases the strain rate as well as the level of strain reached at the end of the test. The tests did not allow to clearly observe the influence of frequency on the response of the material, due to problems of repeatability. In order to avoid such problems, another test procedure was adopted. It consisted in changing either confinement or frequency during the test, with the purpose to see an evolution of strain rate, and to establish correlations. These tests have clearly shown the influence of cyclic loading and the relative influence of loading frequency on the response of asphalt concrete. The main objective of this triaxial programme is to develop a numerical model, based on rheological laws, able to predict the behaviour of bituminous layers.

In recent years, as a result of both envi-ronmental policy and industrial economic strategy, the amount of asphalt pavement that has been recycled has risen dramatically. As a result of this, several inter- national research projects have shown the need for improvements in reclaimed asphalt (RA) character- isation to support these higher recycling rates. During the life of a pavement, as well as the structural damage induced by traffic, the intrinsic properties of asphaltic materials are affected through the oxidative ageing of the bituminous binder. The molecular changes asso- ciated with this oxidation can be monitored via variations in Fourier transform infrared (FTIR) spec- tra. Therefore, if the relationships between binder properties, such as penetration, softening point and complex shear modulus and the spectra parameters can be established, the characterisation of RA pro- duced by the milling of old pavements can be greatly improved. However, the interpretation of oxidation parameters from these spectra is not straightforward, and many different techniques are used to calculate them in the asphalt community. This paper gives a brief overview of asphalt oxidation and the FTIR principle. It then presents the results from four different calculation methods for the oxidation param- eters applied to a set of more than 100 spectra obtained during the RILEM TC-ATB-TG5 round robin test. From this study, it is obvious that the conclusions of the analysis performed on the same set of raw spectra can differ considerably according to the FTIR oxida- tion index calculation method adopted. Using the RILEM database, the potential links between a given ageing index and the physical properties are then evaluated. As a result of this study it can be concluded that ageing comparison through FTIR should be considered as relative and restricted for use in measurements at different ageing steps on the same type of initial mixture. For FTIR spectra to be comparable between different laboratories, harmoni- sation of the data acquisition procedures is needed. Also the different calculation methods of the oxidation indicators seem to reflect different physical properties. So a first step toward harmonisation would be to agree on the relevant physical properties actually needed for efficient RA characterisation. This could then lead to a common FTIR index calculation method, which would reflect the properties of interest. For this, additional research is needed to improve knowledge of the relationship between the chemical oxidative process of a binder and the evolution of its physical properties

Aging of asphalt binders leads to damage on pavements, due to changes in their rheological behavior and in the binder composition. A hardening of the asphalt can be observed, mainly caused by the oxidation of the asphalt binder itself. Oxidation rate is influenced by temperature, ultraviolet radiation and intrinsic characteristics of materials. In order to be characterized, the binder is extracted from the field-aged asphalt cores that use to have several centimetres in thickness. The aging process, however, depends on the access of oxygen into the field core which varies with the distance from the pavement surface. In order to know the aging conditions of the pavement surface (only) and to evaluate their influence on the adhesion characteristics, it is necessary to recover the surface asphalt binder. Only the surface binder is exposed to ultraviolet rays and weathering. A new test method has been developed in this work. It is based on the asphalt binder recovery from the upper part of the asphalt mixture layer. This method was validated by the infrared spectrometry through comparison with the neat asphalt binder (aged and not aged) and with the conventional extraction. In addition, an accelerated aging protocol was developed with the use of a climate chamber comprised of brightness settings, and moisture and weather conditioning, to relate to the French climate. The aging results obtained in the laboratory and in the field were compared using the same test method. This comparison allowed the establishment of an accelerator factor with respect to the increase of sulfoxide and carboxyl groups. This study provides a better understanding of the influence of aging on the skid resistance and the ability of the material to resist to polishing

This chapter focuses on permanent deformation, which is at the origin of pavement rutting. First experimental laboratory tools and associated analyses related to permanent deformations are presented. It is either material tests, that can be homogeneous or giving a simple empirical characteristic, or non-homogeneous Structural/Specimen tests.

This chapter first presents the results of a survey perfomed on the practices used in Europe. This survey is first report on the subject and could be usefully completed by the states of the art prepared in the framework of the Re-road and Direct-Mat European projecys.

In the framework of the RILEM TC 206-ATB TG3, a Round Robin Test (RRT) has been performed in order to evaluate the reproducibility of the French Wheel Tracking Test (FWTT) on a mix made with Polymer Modified Bitumen (PmB). For this mixture, some particular problems had been reported, such as heating of the sample due to friction and sticking of the binder to the wheel. Two procedures, called anti-overheating and anti-sticking procedures, have been proposed by the group in order to improve the reproducibility of the wheel tracking tests. These procedures are assessed. Causes of scattering are discussed. Differences between the tyres used during this RRT as a possible origin of scattering are discussed, as well as temperature peaks and over-compaction of specimens.

Pour étudier les déformations permanentes des enrobés bitumineux, un essai triaxial thermo-régulé a été mis au point. Des essais de fluage statique à différents déviateurs, confinements et différentes températures ont permis d'étudier l'influence de ces paramètres sur le comportement des enrobés. Un modèle viscoélastique-viscoplastique a été développé et présente de bonnes capacités pour simuler les essais de fluage.

The paper presented first results elaborated during the European Research Project Re-road which aims at the development of techniques for increasing the recycling rates of reclaimed asphalt. During service life surface asphalt courses are subjected to aging due to oxidation effects which causes the hardening of the binder and thereby a change in the chemical, physical and mechanical properties of the material. Surface courses often contain highly modified binders as well as special additives for improving the performance characteristics. As these layers inhibit the shortest service lives compared to other road construction layers every year high amounts of reclaimed surface asphalt are available for recycling. The question is raised how the reclaimed asphalt consisting of high quality and costly material components can be recycled for optimal added value. To analyze the asphalt mix service life performance and its recyclability during mix design a laboratory method was developed to simulate the real in-situ aging. First the effects of site aging on the binder and asphalt characteristics were presented. Three laboratory aging methods were discussed which aimed the accelerated aging which meets similar property changes as site aging. At last the effects of two different laboratory aging methods on the same SMA mixture were compared.

Rutting is one of the main modes of degradation of bituminous pavements. In order to study the rutting behaviour under realistic stress states, the Laboratoire Central des Ponts et Chaussées (LCPC) has acquired a new cyclic triaxial apparatus for bituminous materials. This apparatus allows to perform cyclic tests in compression and tension, on 80 mm or 100 mm diameter specimens, at controlled temperatures between 0 and 60 °C. Axial and radial strains are measured on the sample. This paper describes the experimental work that is going on at LCPC using this new device and the conclusions of these first tests. The first part of the paper presents the experimental device. The choice of appropriate test conditions, for the study of permanent deformations is also discussed, on the basis of the modelling of stress states in pavement layers under traffic loading. The second part of the paper presents first experimental results of creep tests at constant stress and at constant strain rate performed with the triaxial apparatus. Based on these results and complex modulus tests, parameters of the DBN visco-elasto-plastic model have been determined. A first assessment of the capacity of this model.

In general, four factors need to be accurately and simply accounted for on the design of flexible pavements: traffic and loading, environmental conditions, materials properties and failure criteria. The inclusion of charge-while-drive technologies inside road infrastructures modifies not only the common disposal of layers, but also the overall response of the structure to thermal and mechanical loadings. In order to quantify the impact of these inclusions on the performance of flexible pavements, this study proposes both numerical and experimental methodologies to measure temperature, stress and strain evolutions within electrified roads (eRoads). By means of transient 2-D FEM thermo-viscoelastic simulations, traditional and electrified road profiles were subjected to daily temperature fluctuations and to traffic. The eRoad studied contains electrified rails embedded in the bituminous wearing course, a case of particular interest due to its direct exposure to traffic and climate. The response of the structures was analysed and compared to admissible values commonly assessed to predict distresses: the vertical compressive strain on the top of the subgrade (permanent deformation) and the horizontal tensile strain at the bottom of the bituminous layer (fatigue life). The rigid inserts were found to affect the temperature distribution inside the layers. The repeated volumetric variations of each component due to temperature fluctuations generated strain in the bituminous layer, in magnitudes that can lead to premature failure and cracking. In laboratory, a thermal test was proposed to evaluate eRoad specimens undergoing warm and cold cycles by means of Digital Image Correlation (DIC) technique. The application of the DIC technique to obtain the contraction/expansion thermal coefficients of the materials is considered accurate and reliable, although some boundary conditions of the test might need improvements to minimize external sources of deformation and background noise. The strain fields measured numerically and experimentally lead to the same conclusion: the rigid inserts generate additional strain along the interface of the charging unit and the bituminous layer solely due to daily temperature fluctuations. The thermosviscoelastic model proposed and the experimental set-up have a great potential to assess innovative pavement profiles (inductive and conductive eRoads). Em geral, quatro fatores devem ser considerados com precisão e simplicidade em projetos de pavimentos flexíveis: tráfego e carga, condições ambientais, propriedades dos materiais e critérios de falha. A inclusão de tecnologias de carregamento dinâmico de veículos na infraestrutura rodoviária altera não apenas o perfil tradicional em camadas dos pavimentos flexíveis, mas também sua resposta estrutural às solicitações térmicas e mecânicas. Para quantificar o impacto dessas inclusões no desempenho do pavimento, este estudo propõe metodologias numéricas e experimentais para medir a evolução dos campos de temperatura, tensões e deformações em rodovias eletrificadas (eRoads). Por meio de simulações termoviscoelásticas transientes usando Método de Elementos Finitos (MEF), em 2D, perfis de rodovias tradicionais e eletrificadas foram submetidos a flutuações diárias de temperatura e ao tráfego. A eRoad estudada contém trilhos eletrificados embutidos na camada superficial betuminosa, um caso particularmente interessante devido à sua exposição direta ao tráfego e ao clima. A resposta das estruturas foi comparada com valores admissíveis comumente utilisados para prever danos: a tensão de compressão vertical no topo do solo de fundação (deformação permanente) e a tensão de tração horizontal na fibra inferior da camada betuminosa (vida de fadiga). As inserções rígidas afetaram a distribuição de temperatura dentro das camadas. As repetidas variações volumétricas de cada componente devido a flutuações de temperatura geraram deformações na camada betuminosa, de uma ordem de grandeza que pode levar a falhas prematuras e fissuras. Em laboratório, foi proposto um teste térmico para avaliar corpos de prova de eRoad submetidas a ciclos de calor e de frio usando a técnica da Correlação Digital de Imagens (DIC). A aplicação da técnica DIC para obter os coeficientes térmicos de contração/expansão dos materiais foi considerada precisa e confiável, embora algumas condições de contorno do ensaio precisem de melhorias para minimizar fontes externas de deformação e ruído. Os campos de deformação medidos numericamente e experimentalmente levaram à mesma conclusão: as inserções rígidas geram deformações adicionais ao longo da interface entre a unidade de carregamento e a camada betuminosa devido apenas às flutuações diárias de temperatura. O modelo termoviscoelástico e a configuração experimental propostos têm grande potencial para avaliar perfis de pavimentos inovadores (eRoads indutivas e condutivas).

Le recyclage des enrobés bitumineux fabriqués selon un procédé tiède répond aux exigences du développement durable: il limite lapport de matériaux neufs, permet la gestion des déchets et réduit la consommation d\'énergie. Le recyclage des enrobés date des années 70 ; ce qui a changé depuis, cest la volonté de pérenniser le recyclage à fort taux, définit ici à plus de 25% dagrégats denrobés (AE). Les AE contiennent une part de bitume qui est valorisable pour ses propriétés viscoélastiques de liant hydrocarboné. Il est ainsi recherché une mobilisation de ce liant vieilli dans le processus de recyclage. Lun des problèmes suspectés lors du couplage recyclage/procédé tiède est le phénomène de double enrobage pouvant impacter la rhéologie du nouveau matériau: le liant de lAE et le liant dapport ne se mélangeraient pas totalement du fait de labaissement des températures de fabrication et formeraient des couches superposées. Ce phénomène serait la cause de dysfonctionnements mécaniques au niveau de lenrobé. Il se pose donc la question de la qualité de lenrobage de surfaces granulaires déjà enrobées et du manque de moyens de caractérisation pour lobservation in situ de linterface. Dans ce travail de thèse, la qualité denrobage des agrégats denrobés par un liant dapport a été évaluée à léchelle microscopique et macroscopique. Au niveau microscopique, il a été proposé dutiliser un outil de micro-spectroscopie infrarouge pour évaluer in situ la qualité dinterface entre lAE et le liant dapport et suivre la répartition spatiale de ces deux composants au sein denrobés de laboratoire. Cela a nécessité un important développement expérimental afin de pouvoir appliquer un accessoire dimagerie infrarouge aux mélanges complexes que sont les formules denrobés bitumineux constitués de différentes fractions granulaires et de liant bitumineux. Il a ainsi été possible, grâce à lidentification préalable de traceurs internes, de suivre la remobilisation partielle du liant vieilli de lAE. En parallèle, au niveau macroscopique, un protocole dessai a été développé afin dévaluer la durabilité des enrobés contenant des forts taux dAE (50%), notamment des enrobés fabriqués selon un procédé tiède. Lessai actuel de fatigue est lun des essais qui permet le mieux dévaluer la durée de vie dune couche de chaussée. Mais cet essai accéléré est biaisé car le bitume des échantillons testés na pas eu le temps de vieillir comme cest le cas sur une vraie chaussée. Dans ce travail, il a donc été proposé dajouter une étape de vieillissement du matériau avant les essais de fatigue, dorniérage, de tenue à leau et de module complexe. Il est supposé que le comportement réel du matériau se situerait entre celui du matériau non vieilli et celui du matériau vieilli. Les principaux résultats obtenus montrent qu\'un enrobé tiède contenant un taux élevé dAE présentent de bonnes performances mécaniques excepté quil a tendance à être plus sensible à la fatigue quune même formulation de matériau fabriqué à chaud ou selon un procédé tiède mais sans ajout AE. A reciclagem de misturas asfálticas usando técnicas de misturas mornas atende às exigências da sustentabilidade, limitando o consumo de energia e de novos materiais. A reciclagem de revestimentos asfálticos fresados (RAP) é praticada há mais de 40 anos, por meio de usinagem a quente do RAP adicionado a agregados e ligante novos. Todavia, o uso de elevadas taxas de RAP (acima de 25% no total), é um grande desafio até o presente, pois limita a perda de durabilidade da mistura asfáltica final. O RAP contém ligante asfáltico envelhecido aderido aos agregados, porém uma parte desse ligante pode ser remobilizada durante a reciclagem pelo aumento da temperatura no processo de usinagem. Esta tese busca compreender o processo de remobilização do ligante envelhecido durante a reciclagem do RAP e as consequências da magnitude de temperatura empregada no processo de reaquecimento deste material envelhecido. Atualmente, tem-se buscado o uso da tecnologia de usinagem morna, permitindo a redução de temperatura total no processo de fabricação. Um dos problemas possíveis da combinação das técnicas reciclagem morna é a ocorrência do fenômeno de recobrimento duplo, que pode impactar na reologia do novo material: o ligante do RAP e o ligante novo não se misturariam totalmente, devido à redução das temperaturas de fabricação, formando camadas superpostas. Este fenômeno seria a causa de disfuncionamentos mecânicos da mistura asfáltica final. Questiona-se então a qualidade do recobrimento dos agregados do RAP, já recobertos, e a falta de um meio de caracterização para a observação da interface. Neste estudo, a qualidade do recobrimento do RAP foi avaliada em escala microscópica e macroscópica. No nível microscópico, foi proposto o uso de uma ferramenta de micro-espectroscopia infravermelha para avaliar a interface entre o RAP e o ligante novo, e seguir a distribuição espacial desses dois componentes na mistura asfáltica. Para tanto, foi realizado um desenvolvimento experimental detalhado que permitisse o uso de um acessório de imagem infravermelha em misturas asfálticas recicladas. Graças à indentificação prévia de marcadores internos, foi possível acompanhar a mobilização parcial do ligante envelhecido do RAP. Em paralelo, no nível macroscópico, foi desenvolvido um protocolo de ensaio com o objetivo de avaliar a durabilidade das misturas asfálticas recicladas com taxas elevadas de RAP (50%), com o objetivo princial de compreender se há benefícios nas propriedades mecânicas de misturas mornas recicladas. O ensaio de fadiga é um dos ensaios que permitem melhor avaliar e comparar diferentes misturas asfálticas para comporem uma camada de pavimento. Porém, este ensaio não pode ser diretamente transposto à previsibilidade de campo por ter restrições, tais como o ligante das amostras ensaiadas não teve tempo de envelhecer; e as misturas asfálticas, dependendo da quantidade de RAP e da temperatura de usinagem, podem envelhecer em velocidades diferentes em campo. No presente trabalho, foi proposta a adição de uma etapa de envelhecimento previamente aos ensaios mecânicos. Foi suposto que o comportamento real do material estaria situado entre o do material não envelhecido e do envelhecido. Os principais resultados mostram que uma mistura reciclada morna apresenta resultados satisfatórios de comportamento mecânico que atestam seu uso como camada de revestimento asfáltico, exceto que ela tem a tendência de ser mais sensível à fadiga que uma mistura com a mesma composição de agregados e de teor de ligante, fabricada a quente ou morna, mas sem a adição de RAP.