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This paper focuses on the influence of air void content and loading frequency on the fatigue resistance properties of bituminous mixtures. Fatigue tension–compression tests were carried out...

The present paper describes the rutting behavior of innovative mixes incorporating 50% of Reclaimed Asphalt (RA) with bio-materials. They were assessed in the laboratory and in a full-scale accelerated experiment. The innovative mixes studied here contained bio-materials especially designed to help recycling by re-activating the aged binder from RA. Four mixes were evaluated: three of them are manufactured with bio-materials, (two bio-rejuvenators and one bio-binder) and one was a control mix, which was a high modulus asphalt mix (EME2). In this study, the rutting resistance of the four mixes was first evaluated in the laboratory with both European and US methods. The full-scale test was then performed in order to evaluate the rutting resistance of the bio-recycled asphalt mixes under heavy traffic (200,000load cycles loaded at 65kN) and compared with the control one. A simplified analysis leads to the conclusion that, with the Nantes climate, a daily traffic of 150heavy vehicles per day applied over 20years corresponds to approximately 200,000heavy vehicle loads when the surface temperature exceeds 30°C. Therefore, it can be considered that the rutting evaluation made on the carrousel represented almost 20years of traffic during hot-day periods. The results obtained on the test track were consistent with the laboratory rutting tests showing good performance for all the mixes. The materials presenting the best performance on the test track also presented the best performance in the laboratory.

The recent drive to find ways to increase sustainability and decrease costs in asphalt paving has led researchers to find innovative ways to incorporate more recycled materials and bio-derived binders into mixes with varying success. A new novel bio-derived binder made from refined pine chemistry stabilised with a polymer can increase the sustainability of asphalt mixes while maintaining pavement performance. Laboratory performance testing was conducted on asphalt mixes containing 50% Reclaimed Asphalt Pavement (RAP) by mix weight and the novel bio-derived binder. Results show that the bio-derived binder outperforms the conventional 50/70 pen grade binder mixes with respect to resistance to thermal cracking and adequately passes all requirements for pavements with 20-year design loadings of less than 30 million ESALs. This research shows that asphalt mixes containing 50% RAP and a bio-derived binder can be designed to pass performance criteria at low, intermediate, and high temperatures without the need of neat bitumen.

International audience; Tunnel boring muds, coming from underground works, are considered as specific materials due to their intrinsic characteristics (granularity, clay content, water content, presence of heavy metals). In order to determine if they can be valorized in road construction or civil engineering, a complete characterization, including their environmental behavior, is necessary. Thus, the aim of this study is to characterize a tunnel boring mud sample from chemical, mineralogical, and environmental point of view. The studied material, a limestone mud, was characterized using different analytical techniques. Some pollutants and heavy metals were identified, such as sulfates and molybdenum (Mo), and specific analyses were performed to identify molybdenum speciation. As molybdenum was detected as traces in the studied material, it was necessary to increase its concentration. Thus, a nitric acid extraction was specifically developed at a laboratory scale with the aim to remove its high-calcium carbonate content. Then, synchrotron analyses were performed, allowing to obtain data on the oxidation state of molybdenum.

The present paper describes the full-scale accelerated test, carried out on asphalt pavements made up with bio-materials, especially designed to help reusing Reclaimed Asphalt (RA) by re-activating the aged binder. Four pavement sections were evaluated: three pavement sections with innovative bio-materials (bio-recycled asphalt mixtures), and a reference section with a conventional, high modulus asphalt mix (EME2). In this study, fatigue resistance was first evaluated in laboratory, with two-points bending test, and then at full scale under heavy traffic loading, with the IFSTTAR accelerated pavement testing facility. The evolution of bio-materials recycled asphalt mixture characteristics, as well as the pavement distresses, were recorded and analyzed. The structural condition of the pavement sections was monitored periodically through falling weight deflectometer (FWD) measurement as well as with strain gauges and temperature sensors. Although the reference EME2 mix presented the highest fatigue resistance in laboratory, on the full scale test, the three bio-based asphalt mixtures performed similarly or better than the control EME2 mixture.

Hypotheses: The influence of binder properties on rheological behaviour of mixtures (produced with different contents of Reclaimed Asphalt Pavement and base binders) was investigated. Bitumen is responsible of the viscoelastic nature of mixture behaviour. Therefore, if mechanical properties of bituminous binders depend on their chemical composition and colloidal structure, then proportions of colloidal fractions of binders are expected to be related to linear viscoelastic modelling of mixtures. Experiments: Complex modulus tests results obtained on mixtures were fitted with analogical 2S2P1D (2 Springs, 2 Parabolic elements, 1 Dashpot) LVE model. Classical semi-empirical tests were performed on corresponding binders (pure and blends), while their colloidal structure was investigated by performing SARA (Saturates, Aromatics, Resins, Asphaltenes) fractioning. Correlations were observed between 2S2P1D parameters of mixtures and binder test results. Findings: 2S2P1D parameters of mixtures showed to be related to results of semi-empirical tests and SARA fractioning of corresponding binders. In particular, mixture parameters k and h and τ0 (at 15 °C) show successful correlations with asphaltene content and Colloidal Index of binders, as well as to penetration (at 25 °C), softening point and Fraass breaking point. Keywords: Bituminous mixtures, Binder blends, Colloidal structure, LVE behaviour, 2S2P1D model, Sara

International audience

International audience

An ongoing study on influence of hydrated lime on mechanical properties of bituminous mixtures is carried out. In this paper we focus on Linear ViscoElastic (LVE) properties and fatigue behavior. Nine mixtures were produced with the same 35/50 penetration grade bitumen, three different bitumen contents (4.4%, 5.1%, 5.8%) and three different hydrated lime contents (0%, 1.25%, 2.5%). Hydrated lime replaces a part of limestone filler (the mass of removed filler for the same mass of added hydrated lime). LVE properties of mixtures (complex Young’s modulus) were determined using a tension/compression test developed at University of Lyon/ENTPE. In the same time, two points bending tests were used to evaluate fatigue resistance. Surface response methodology and ANOVA (ANalysis Of VAriance) were carried out on experimental data obtained for different responses in order to evaluate the influence of bitumen content and hydrated lime content on linear viscoelastic properties and fatigue resistance. Time-Temperature Superposition Principle (TTSP) was verified with good approximation using very close shift factors for all tested materials. The use of hydrated lime filler (instead of limestone filler) induces an increase of complex modulus. Its effect increases with hydrated lime content. Hydrated lime does not change fatigue resistance of mixtures.

Sound absorption coefficients of bituminous mixtures are predicted owing to image analysis. A three-parameter semi-phenomenological model, well adapted to porous road materials, is used. Three geom...

The objective of the presented study is to determine linear viscoelastic (LVE) properties of corresponding binders and mixes and to check how they change with reclaimed asphalt pavement (RAP) content. The investigation is part of a wider on-going research project, in the framework of a PhD thesis, in collaboration between Universite de Lyon/Ecole Nationale Travaux Publics de l'Etat (ENTPE), EIFFAGE Travaux Publics and Beyond Petroleum. Dynamic shear rheometer and tension/compression (using a Metravib device) complex modulus tests were performed on nine different bitumens, produced as blends of two different base bitumens and RAP-extracted bitumen in various proportions. LVE properties of six asphalt mixes, produced with the same materials and proportions of certain bitumen blends among the nine tested ones, were measured in tension/compression mode. 2 Springs, 2 Parabolic Elements, 1 Dashpot model was used to fit experimental data both for binders and mixes. Shift-Homothety-Shift in time-Shift transformation (developed at ENTPE) was applied to verify the correspondence of LVE behaviours of related binders and mixes.

The paper focuses on the investigation of the effects of a recycling agent on mechanical performances of bituminous mixtures produced with reclaimed asphalt pavement (RAP). Twenty-one different bituminous mixtures were produced and tested, using three distinct virgin binders (15/25, 35/50 and 70/100 penetration grades), with RAP contents varying from 0% to 60%. Seven of the mixtures were produced by adding a recycling agent of vegetable origin (its content was fixed equal to 3.5% by weight of the RAP binder). One of the mixtures is a 100% RAP mixture, produced only with RAP-extracted binder and aggregates issued from RAP material. Another one is a “perfect” mixture, produced by perfectly blending 70/100 base binder with 60% RAP-extracted binder and using this blend to coat virgin and RAP aggregates. Material properties were investigated using classical tests commonly performed by the road paving industry in Europe, in order to assess the impact of the addition of the recycling agent according to the curre...

Aggregate packing concepts developed in the field of high-performance cement concretes, initially by Caquot (1937) then by contemporary researchers since the 1970s, were transposed to the field of asphalt concretes. These concepts, associated with the use of the gyratory compactor on aggregates only, enabled the development of a new laboratory design procedure of dense high-modulus asphalt concretes. These mixes are characterized by single or double gap-graded curves, great coarse aggregate interlock and no need for low penetration grade bitumens to fulfil the European EME2 specification requirements, in particular the 14,000 MPa stiffness modulus value at 15°C. In addition, the use of polymer modified binders (PMBs), at a content of about 4% up to 4.5%, combined with such an optimized aggregate packing leads to the design of the so-called high-performance asphalt concretes (HPAs) characterized by great compactability, very high stiffness modulus and high fatigue resistance in a single formulation, allowi...

The present paper deals with the energy dissipation induced by the viscous behavior of bituminous materials constituting pavement. An approach to take into account viscous properties of bituminous layers and to quantify this dissipation is explained. First, the behavior of different bituminous materials is investigated. Linear viscoelastic modeling is then proposed using a rheological model previously developed at the Civil Engineering and Buildings Department (DGCB) of the University of Lyon / ENTPE (Ecole Nationale des Travaux Publics de l’Etat). Second, this model is implemented in a finite-element code, which enables simulation of the behavior of any pavement structures under any rolling load. In this paper, these developments, previously validated for orthotropic steel bridge and mix surfacing structures, are applied on a classical French pavement structure. In addition, the calculation of energy dissipation due to the viscous properties of the bituminous materials is allowed. Then an estimation of corresponding fuel consumption excess is given considering a 40-ton truck for different temperatures and speeds. The influence of the base course thickness is investigated as well. The simulation results show that energy dissipation in bituminous pavement due to the rolling weight of the considered 40-ton truck may induce a fuel consumption excess of a few percents age points in very unfavorable climatic conditions.

This paper deals with the influence of a bituminous mix surfacing on the orthotropic deck bridges. These researches are part of a French national project “Orthoplus”, which is briefly introduced. The approach to take into account the surfacing and to develop calculation tools is explained. First the behavior of the different bituminous constituent materials is investigated. A linear visco-elastic modeling is proposed with a rheological model, previously developed at the Civil Engineering and Buildings Department (“DGCB”) of University of Lyon/ENTPE. This model was implemented in a Finite Elements code, which enables the simulation of any orthotropic structures. In order to validate these developments, two orthotropic structures are studied, including the highest bridge in the world, the Millau Viaduct (France). In situ measurements were especially carried out on the Millau Viaduct. The analysis is also performed on the French five-point bending fatigue test used at the EIFFAGE Travaux Publics research center in parallel to the construction, in 2004, of the Millau Viaduct. Focus is made on comparisons between experimental data and simulations results.

In the framework of a partnership between the European EIFFAGE Travaux Publics Group and the Ecole de Technologie Superieure (ETS) from Montreal (Quebec), some basic concepts associated with granular combinations and aggregate packing characteristics enabled the development and design of high-performance self-blocking asphalt concretes. The aggregate packing methods first developed in the field of high-performance cement concretes were successfully transposed to the field of asphalt concretes. Laboratory assessment in both laboratories of the ETS and EIFFAGE Travaux Publics consisted in the evaluation of the compactin g ability using the French gyratory shear compactor (GSC), the resistance to moisture using the so-called Duriez test, the resistance to rutting thanks to the French wheel tracking tester at 60°C, the secant stiffness modulus at 15°C and the fatigue resistance at 10°C. The paper concludes that the grading analysis concepts allow the design engineer new insights into the structure of...

A new approach is proposed to determine the global response of an orthotropic bridge structure from the behavior of the constituent materials that are binders, aggregates and steel. Experimental results and modeling using constitutive models (2S2P1D and DBN) developed by ENTPE team are presented for the bituminous materials in the linear domain. From these results, a transformation that is independent of the introduced models allows the bituminous mix complex modulus to be predicted from the bitumen complex modulus. Then, the response of a 3D orthotropic steel deck bridge subjected to moving wheel loads is presented using numerical Finite Element Method (FEM). The influence of temperature and viscous behavior of surfacing layers on the structure response such as deflection and longitudinal stress are emphasized.

The structural role of the wearing courses on orthotropic steel deck bridges is usually not estimated during the design process. Both geometry of the structure and very high flexibility of steel plates induce severe stress and strain fields in the steel bridge surfacing. In this paper, we quantify the influence of a bituminous mix surfacing on the steel plate response when considering the French Five-Point Bending Fatigue Test. Mechanical behavior of bituminous mixes is very complex. It includes a great thermal sensitivity. Moreover in the small strain domain (for strain amplitudes below about 10−4) the behavior can be considered as linear. Therefore, the theory of linear viscoelasticity can be applied. After introducing the French five-point bending fatigue test used at the research center of “EIFFAGE Travaux Publics” company, in parallel to the construction of the Millau Viaduct (France) -the highest bridge in the world-, a numerical parametric study using the Finite Element Method (FEM) is presented. The specimens are made of a 12-mm-thick steel plate, a 3-mm-thick sealing sheet and a 60-mm-thick bituminous mix. Different wearing course behaviors are considered introducing temperature and viscous effects. This behavior is modeled using the linear part of the general thermo-viscoplastic model «DBN» (Di Benedetto and Neifar), recently developed at ENTPE laboratory and briefly described in this paper. An important observation is that the rigidity of the intermediate bituminous sealing sheet as well as the wearing course behavior seems to have a great influence on the orthotropic multilayer specimen complex behavior.

Since 2008, EIFFAGE has developed an aggregate optimization method (maximum contact and minimum space between aggregate particles) combined with the use of special binders (pure, multigrade or polymer-modified bitumen depending on the traffic concerned), to formulate the high-performance asphalt bituminous mix known as GB5®. During that time, numerous roads designed for heavy traffic have been built using this innovative technique, representing more than 1,000,000 tons at the end of 2014, mainly in France and, more recently, in South Africa. This article presents the result of collaboration between IFSTTAR and EIFFAGE aimed at scientifically relating the specific characteristics of the aggregate skeleton of GB5® to its outstanding mechanical properties, via 2D-image analysis and complete mechanical characterization.

Considerable research efforts are made to develop methods to predict mechanical behavior of bituminous mixtures from properties of basic components. In particular, such methods would be most useful for the design of mixtures containing Reclaimed Asphalt Pavement (RAP) material. The objective of the study is the simulation of Linear ViscoElastic (LVE) behavior of bituminous mixtures containing RAP from LVE properties of base constituents. Five mixtures were produced and tested, a reference mixture produced only with 35/50 binder, a mixture containing 100% RAP and three mixtures produced with 35/50 binder and different RAP contents (20%, 40% and 60%). All mixtures had the same granular size distribution curve. Complete LVE characterization was carried out on all materials. DSR and Tension/Compression (T/C) tests were performed on base and RAP-extracted binders (from -30 C to +70 C and from 0.01Hz to 30Hz). T/C tests were carried out on mixtures (from -25 C to 40 C and from 0.001Hz to 10Hz). Test results on both binders and mixtures were successfully fitted with 2S2P1D (2 Springs, 2 Parabolic elements, 1 Dashpot) model. LVE behavior of mixtures containing RAP was simulated by using as input data only LVE properties of base binders (35/50 and RAP-extracted binders) and of the reference mixture (produced with 35/50 binder, without RAP). In order to do this, two existing procedures, previously developed at the ENTPE, were used conjunctly. The first procedure was applied to predict LVE behavior of binder blends of pure base and RAP-extracted binders over the whole range of frequency and temperature. This procedure allows estimating 2S2P1D parameters of binder blends from those of base bitumens, according to their proportions in the blend. Therefore, LVE properties of blends can be predicted over the whole range of frequency and temperature. The second procedure used is SHStS (Shift, Homothety, Shift in time, Shift) transformation. This analytical tool is useful to determine the relationship between LVE behavior of mixtures and their corresponding binders. Experimental data of pure 35/50 binder and its corresponding mixture (without RAP) were used to calibrate SHStS transformation, depending mainly on aggregate skeleton. LVE behavior of mixtures produced with RAP was then estimated from simulations of LVE properties of blends, having the same proportions of base binders, obtained with the first procedure. Simulations of LVE behavior of mixtures containing RAP were finally compared to T/C test data. Successful correspondence was found between predicted and experimental results. Small discrepancies observed can be reasonably attributed to incomplete blending of base and RAP binders within the mixture. Therefore, as a first approximation, the proposed procedure can be used to predict LVE behavior of mixtures produced with RAP, over the whole range of frequency and temperature, from LVE properties of base binders and of a reference mixture (with the same granular size distribution) are known.

The DBN model, so called from its authors Di Benedetto and Neifar, has been developed, based on simple rheological elements and experimental results on bituminous materials. This model was developed thanks to the large amount of data obtained during the last two decades in the DGCB laboratory. In previous works, the development of the model has been limited to a unidirectional formulation. Nevertheless, the ability of this model to take into account the complex thermo-viscoplastic behaviour of bituminous material in different domains of loading is shown in this paper. In order to simulate the real behaviour in the pavements, the DBN model has been extended to a 3D formulation, which is described in the paper. The calibration of DBN model is also explained. Numerical simulations are compared with some few available data, considering the 3D behaviour of these materials.

The objective of the paper is to investigate the influence of bitumen nature on complex modulus and fatigue resistance of bituminous mixtures produced with reclaimed asphalt pavement (RAP). Eight distinct mixtures were produced with eight different modified and unmodified base binders. RAP content was fixed equal to 20% for all mixtures. For each mixture, the corresponding binder blend was produced by mixing the base binder with RAP-extracted binder, in the same proportions. A total of 16 binders (eight base binders and eight binder blends) were therefore used in the study. Both advanced and classical tests commonly used by road paving industry in Europe were performed. Complex modulus (at 15°C and 10 Hz) and fatigue (at 10°C and 25 Hz) DSR tests were carried out on all binders. Two-point bending complex modulus (at 15°C and 10 Hz) and fatigue (at 10°C and 25 Hz) tests were carried out on trapezoidal samples of mixtures. Complex modulus and fatigue resistance of mixtures appeared to vary significantly depending on the nature of the base binder. However, clear correspondences between values obtained for mixtures and corresponding binders could not be found.

Various phenomena other than fatigue (so-called “biasing effects”) occur during laboratory fatigue tests on asphalt mixes because of cyclic loading applications, thus altering experimental results and leading to misleading conclusions. The purpose of the study is to isolate and quantify biasing effects, therefore isolating real fatigue damage. In particular, non-linearity, self-heating and thixotropy (defined as a recoverable viscosity reduction after shear application) were evaluated. Six different mixes were produced using three distinct asphalt binders. Tests were performed in tension/compression mode on cylindrical samples. A particular test procedure was followed, consisting of two parts. In the first part, complex modulus measurements were performed at temperatures from 8°C to 14°C and strain amplitudes from 50 to 110 µm/m, at 10 Hz. Regression equations were fitted in order to evaluate variations of norm of complex modulus and phase angle caused by temperature and strain-level changes around common...

This study aims at understanding from a statistical point of view the influence of several mix constituents on mechanical properties of asphalt mixes produced with RAP material. The study is developed in two steps. The first section is focused on the qualitative evaluation of the effect of varying certain mix design parameters (aggregate and filler nature, binder content and type) on mechanical properties of mixes containing 20 % of RAP material. Results of the statistical analysis showed that changes in binder nature and binder content have a statistically significant influence on complex modulus of mixes. The second section aims at quantitatively estimating the influence of RAP material content and fresh added binder penetration grade on complex modulus and fatigue life of mixes. Proposed quadratic models satisfactorily fitted experimental data, although some coefficients were not estimated as statistically significant by the software. Observed fatigue and complex modulus performances of mixes containing up to 60 % RAP material are quite encouraging from technical, economical and environmental points of view.

The paper presents an original process to produce a warm asphalt mixture: low-energy asphalt (LEA) with the performance of hot-mixasphalt(HMA). The Kyoto agreements continue to divide the planet, while protocol signatories are defining their application conditions. People wonder what the resulting repercussions will be on their respective fields of activity and their quality of life. A new aggregate coating technique is being presented in that context. The technique, the LEA process, substantially reduces energy consumption and greenhouse gas emissions. The low-energy coating technique LEA (EBE, from the French “enrobage à basse energie” involves the manufacture and application of asphalt mixes at a temperature lower than 100°C. These mixes offer a performance equivalent to that of HMA. They combine the action of the mixing energy, temperature, and water on the components of the mix, its bitumen, and aggregate skeleton. The originality of the process lies in the best use of changes in the condition of the bitumen: fluid when it is hot and able to transform into foam or to emulsify when in contact with water. Moreover the moderate-temperature heating of only the chippings (coarse aggregates) is involved; the rest of the aggregate skeleton is used cold and wet. This technique yields a significant saving in mixing energy and reduces the resulting gas emissions. The paper looks briefly into the process and sets it within its appropriate context.

In 2004, a new European standard (NF EN 12697-26), the object of which is the measurement of stiffness modulus, appeared. It includes five annexes corresponding to five different testing methods, in particular modulus testing in indirect tension (IDT) mode. Given that a typical asphalt layer thickness is about a few centimeters and that coring is the most effective method for obtaining specimens from actual pavements, the IDT testing of cores is bound to become very practical for routine use. Notwithstanding this fact, IDT testing is still of little use in French public and private sector laboratories and, moreover, little information is available in the technical literature concerning the comparison between stiffness modulus data obtained in uniaxial direct tension or tension-compression and in biaxial indirect tension. This paper provides rational understanding, based on principles of linear viscoelasticity in particular, of the moduli commonly used for structural evaluation of asphalt mixtures...

Basically, the behavior of bituminous surfacings on steel orthotropic decks, under heavy truck traffic and environmental conditions, is highly complex. Both the geometry of the structure and the very high flexibility of metallic plates make the deformations and stresses very severe in steel bridge surfacings. In particular, the repeated loading make the fatigue strength be an important parameter for the design of such bituminous wearing courses. In addition, these specific surfacings must also have durability over the expected temperature range, in particular it must be resistant to thermal cracking at low temperatures and to rutting at high temperatures. The technical studies led in parallel to the construction of the Millau Viaduct (France)—the highest bridge in the world- have provided in particular the opportunity of new progress in the development of appropriate laboratory testing equipment and of an original polymer-modified surfacing. A comprehensive research program including both a large...

Within the framework of a partnership between the “Departement Genie Civil et Bâtiment” of the ENTPE, Eurovia and Appia, a research work including a large experimental campaign on the thermomechanical behavior of bituminous materials at low temperatures is proposed. The aim is to establish the links between the characteristics of the binder and the properties of bituminous mixes at low temperatures. Four different bitumens have been used with one type of aggregate and grading. The low temperature behavior of binders was evaluated with three fundamental tests: the complex modulus determination, the Bending Beam Rheometer and the tensile strength at a constant strain rate and constant temperatures. The thermomechanical behavior of bituminous mixes has been studied by performing complex modulus tests, measurements of the coefficient of thermal dilatation and contraction, tensile tests at constant temperatures and strain rates, and Thermal Stress Restrained Specimen Tests. The results are analyzed considering a rational approach. Some pertinent links between binders and mixes properties are established. Characteristics which are pertinent and discriminating enough with regard to the thermal cracking of bituminous mixes at low temperatures are presented.

This paper presents a rational approach for the performance-based design of bituminous wearing surfacings on orthogonally anisotropic steel bridges. The behavior of bituminous surfacings on steel orthotropic decks under heavy truck traffic and environmental conditions is highly complex. Both the geometry of the structure and the high flexibility of metallic plates make the deformations and stresses severe in steel bridge surfacings. In particular, the repeated loading makes the fatigue strength an important parameter for the design of such bituminous wearing courses. In addition, these specific surfacings must have durability over the expected temperature range, and they must be resistant to thermal cracking at low temperatures and to rutting at high temperatures. The technical studies that were conducted in parallel with the construction of the Millau Viaduct (France)–-the world's highest bridge–-have provided in particular the opportunity for progress in the development of appropriate laboratory testing equipment and of an original polymer-modified surfacing. A comprehensive research program, including both a large laboratory testing campaign and a finite element parametric study, was performed to develop a useful tool for the design of plate surfacings.

A large experimental campaign on the characterization of the linear viscoelastic behaviour of different bituminous materials was carried out. The goal was to establish the links between the linear viscoelastic properties (which are observed in the small strain domain) of binders and those of bituminous mixes. The linear viscoelastic behaviour of bituminous binders and mixes was studied by performing complex modulus tests at different temperatures and frequencies. A unique rheological model (called “2S2P1D model”) was developed for the modelling of linear viscoelastic properties of both bituminous binders and mixes. This model consists of a generalization of the Huet-Sayegh analogical model. Analyses on test data for five binders and different mastic and mix composition, show that the introduced model fits quite well the measurements. Finally, from our first results, a transformation that is independent of the introduced model allows the mix complex modulus to be predicted easily and efficiently f...

A research including a large experimental campaign on the characterization of the viscoelastic behavior of different bituminous materials was developed. The aim is to establish the links between the viscoelastic properties (which are observed in the small strain domain) of binders and those of bituminous mixes. The viscoelastic behavior of bituminous binders and mixes has been studied by performing complex modulus tests at different temperatures and frequencies. A unique rheological model has been developed for the modeling of linear viscoelastic properties of both bituminous binders and mixes. This model consists of a generalization of the Huet-Sayegh analogical model. Analyses on test data for nine different binders and four mixes, with one mix design, show that the introduced model fits quite well the measurements. Finally, from our first results, a transformation that is independent of the introduced model allows to predict easily and efficiently the mix complex modulus from the binder one.

Within the framework of a partnership between the DGCB of the ENTPE, Appia and Eurovia, a research program including a large experimental campaign on the viscoelastic behavior of different bituminous materials was developed. The aim is to establish the links between the viscoelastic properties of binders and those of bituminous mixes at low temperatures. The viscoelastic behavior of binders was evaluated using cyclic tests (frequency domain) and Bending Beam Rheometer tests (time domain). The viscoelastic behavior of bituminous mixes has been studied by performing complex modulus tests in tension/compression. Some pertinent links between bituminous binder and mix properties are established. Characteristics which are pertinent and discriminating enough with regard to the low temperature properties of bituminous mixes are presented.

This paper presents a method to evaluate the energy dissipation in the pavement, induced by the viscous behaviour of bituminous constituents. The introduced method starts from the experimental characterization of each material and goes to the determination of stress and strain field, as well as viscous dissipated energy, in a pavement structure under a rolling wheel. A classical French pavement structure is considered as an application example. First, the behaviour of bituminous materials is characterized with advanced complex modulus tests. Second, a rheological model is used to describe the linear visco-elastic behaviour of bituminous materials. This model was previously developed at the Civil Engineering and Buildings Department of University of Lyon/ENTPE and has already shown its ability to describe completely and precisely the observed behaviour of bituminous materials. In order to make calculation the Finite Element software is then used in a third step, with the previous material model. Detailed hypotheses to perform the simulation of a rolling wheel on the pavement structure are explained. Results of the simulation are presented in terms of dissipated energy inside the pavement for a 40 ton truck. To give an order of magnitude, an estimation of the fuel consumption excess is given. Different temperature and vehicle speeds are considered. The Time Temperature Superposition Principle has been applied to estimate the dissipated energy at any temperature and vehicle speed. The simulation results show that energy dissipation in bituminous pavement due to the rolling weight of the considered 40 ton truck may induce a fuel consumption excess of a few percent for very unfavourable climatic conditions.

The main issue with asphalt pavement recycling is the assessment of the influence of aged bitumen in reclaimed asphalt pavement (RAP) material on viscoelastic properties of a blended binder in the final mixture. Blending charts or empirical laws, such as the “log–log” rule, are currently used to estimate grading parameters for material characterisation. However, a true prediction method of linear viscoelastic properties is still missing. The presented study is part of a wider ongoing research effort in the framework of a Ph.D. thesis, in collaboration between University of Lyon/Ecole Nationale des Travaux Publics de l'Etat (ENTPE), EIFFAGE Travaux Publics (ETP) and Beyond Petroleum. The paper focuses on the influence of the RAP-extracted binder content on viscoelastic properties of bitumen blends obtained from different asphalt binders. Three unaged bitumens were blended with a binder extracted from a well-known RAP material in different proportions (20%, 40% and 60%) for a total of 13 different bitumen b...

Polymer modified asphalt mixtures have usually been used in wearing courses in order to improve both crack growth resistance and rutting performance where temperatures, vertical stresses and shear strain levels are more severe. Nonetheless, the need for either thinner yet high-performing wearing courses or ever-increasing durability provides the motivation for using higher polymer contents in the wearing course of bituminous pavements.

This paper deals with the influence of viscous bituminous wearing courses materials on orthotropic steel deck bridges. These researches are part of a French national project “Orthoplus”, which is briefly introduced. The approach to take into account the surfacing behavior and to develop calculation tools is explained. First the behavior of the different bituminous constituent materials is investigated. A linear viscoelastic modeling is proposed with a rheological model, previously developed at the Civil Engineering and Buildings Department (“DGCB”) of University of Lyon / ENTPE. This model is implemented in a Finite Elements software, which enables simulation of any transportation structures considering viscous behavior of bituminous materials.

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.

For several years, as environmental criteria have become stricter and stricter, new moderated-temperature mixing technologies–warm or even half-warm (less than 100°C)–have appeared. This study, realized in Laboratoire Central des Ponts et Chaussées (LCPC) in Nantes, France, within the framework of the partnership between Eiffage Travaux Publics and LCPC, aimed at determining the influence of mixing parameters (such as temperature and initial water content of the mix aggregates) on the quality of mixing and the mechanical properties of the half-warm foamed bitumen mixes compared with the traditional cold-foamed bitumen mix and hot-mix asphalt, both of which acted as reference materials. It was also a way to understand better the role of water and its influence on asphalt quality. This study highlights the influence of the increase in the aggregate temperature to elaborate mix treated with foam bitumen. This coating process allows many benefits: an increase in coating quality, compactibility, and water resistance. As a consequence, mechanical performances are improved.

This paper deals with the influence of a bituminous mix surfacing on orthotropic deck bridges. These researches are part of a French national project “Orthoplus,” which is briefly introduced. The approach to take into account the surfacing and to develop calculation tools is explained. First, the behavior of the different bituminous constituent materials is investigated. A linear viscoelastic modeling is proposed with a rheological model, previously developed at the Civil Engineering and Buildings Dept. (“DGCB”) of the University of Lyon/ENTPE. This model is implemented in a Finite Elements code, which enables the simulation of any orthotropic structures. To validate the proposed numerical tool, the highest bridge in the world, the Millau Viaduct (France) is studied. In situ measurements were especially carried out on the Millau Viaduct. Focus is made on comparisons between experimental data and simulations results. Influence of vehicle speed on bridge response is also analyzed.

The paper presents an attempt to find a relation between Linear ViscoElastic (LVE) behaviour of bituminous mixtures containing Reclaimed Asphalt Pavement (RAP) and colloidal structure of corresponding binders. Three different base bitumens (15/25, 35/50 and 70/100 pen grade) were used to produce nine bituminous mixtures with varying RAP content (0%, 20%, 40% and 60%). Moreover, a 100% RAP mixture was produced (containing only RAP-extracted binder), for a total of ten mixtures. All mixtures have the same aggregates and grading curve. For each mixture, its corresponding binder blend was also produced, by perfectly mixing the base binder with RAP-extracted binder in the same proportions. Tension/Compression (T/C) complex modulus tests were performed on all mixtures, over a large range of frequencies (from 0.001 Hz to 10 Hz) and temperatures (from -25 °C to 40 °C). Experimental results were successfully fitted with the 2S2P1D (2 Springs, 2 Parabolic elements, 1 Dashpot) analogical model, developed at ENTPE. Therefore, for each mixture, a set of 7 model parameters and 2 additional constants (to take into account Time-Temperature Superposition Principle) was obtained. All binders were subjected to penetration tests and SARA (Saturates, Aromatics, Resins and Asphaltenes) fractioning, in order to have an indication on their colloidal structure. Colloidal Index (CI) of each binder was also calculated. Correlations between each parameter and all SARA fraction proportions, corresponding colloidal index values and penetrations are presented and analyzed.