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Regular and long-term infrastructures monitoring is fundamental for asset management, as it provides information on the actual mechanical conditions and triggers maintenance actions. Several tools ...

The influence of the addition of Crumb Rubber (CR) by dry process on the tridimensional linear viscoelastic properties of bituminous mixtures was studied. Advanced complex modulus tests were perfor...

The use of bio-oils and biobinders in recycled asphalt mixtures have attracted the attention of researchers and contractors in the pavement field because they allow the incorporation of higher amounts of recycled material while reducing the consumption of new asphalt binder. However, inclusion of these biomaterials in the blends has led to concerns about the overall performance of the recycled mixture and prompted investigations to identify the proportions required to optimize restoration of the aged binder properties in the recycled material. In this context, this paper presents the verification of blending charts based on high performance grade (HPG) temperature in relation to the restoration of the HPG values and rutting susceptibility for one commercial plant-based binder used as recycling agent in two Brazilian aged asphalt binders. The results showed that to optimize the rejuvenating effect of this biobinder, blending charts based on nonrecovery creep compliance were more efficient. The biobinder was also found to restore, and even improve, the initial properties of the aged binders, which showed the potential of this biomaterial to be used as an effective recycling agent.

Using bio-binder and bio-additives as recycling agents for asphalt mixtures with high-content of reclaimed asphalt (RA) is proving to be feasible. It is still not clear whether this combination might provide new hazardous emissions from airborne binder fumes. The health hazard related to airborne bitumen fume generation is primarily relevant for paving crews while there is little opportunity for exposure related to asphalt plant workers. In this study, measurements of gaseous organic compounds from airborne binder fumes of selected bio-asphalt mixtures have been measured during the laboratory mixing process, by using a thermo-mixer equipped with a chimney at University Gustave Eiffel. Parameters studied are the binder nature, mix formula and mixing temperatures. Results show that generally combining bio-based materials and RA is as safe as using conventional bitumen and RA, however thanks to this approach it was possible to identify a strong link between bituminous material composition and their emission potential

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...

This paper presents a new structure design for a ballast-less and sleeper-less bituminous railway track. The structure is thinner than the conventional French tracks made with granular materials. This makes it especially suited for track renovation works in tunnels and other infrastructure configurations where the respect of the accurate and durable railway track geometry is essential. The proposed structure is a system associating a high-performance bituminous mixture, called GB5®, and the edilon)(sedra Embedded Rail System (ERS) using the Corkelast® resin as rail fastening system. This paper presents details of the components of the proposed structure and of its construction methodology. The system was submitted to mechanical tests to assess its aptitude to serve as rail fastening system in Europe, according to EN 13481 part 5 and EN 13146 part 9 test methods for non-ballasted rail fastening systems. The sample manufacturing and test protocols are described in this paper. The results from two tests are presented and analyzed. The system was found to be resilient and to meet the requirements of the European standard. Further analysis and large scale tests will give more insight into the behavior of the system, especially in terms of permanent deformation of the bituminous mixture and of the supporting soil.

Using bio-binder and bio-additives as recycling agents for asphalt mixtures with high-content of reclaimed asphalt (RA) is proving to be feasible. It is still not clear whether this combination might provide new hazardous emissions from airborne binder fumes. The health hazard related to airborne bitumen fume generation is primarily relevant for paving crews while there is little opportunity for exposure related to asphalt plant workers. In this study, measurements of gaseous organic compounds from airborne binder fumes of selected bio-asphalt mixtures have been measured during the laboratory mixing process, by using a thermo-mixer equipped with a chimney at Univ Gustave Eiffel. Parameters studied are the binder nature, mix formula and mixing temperatures. Results show that generally combining bio-binders and RA is as safe as using conventional bitumen and RA, however thanks to this approach it was possible to identify a strong link between bituminous material composition and their emission potential.

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.

This paper presents some results of a study on bituminous mixtures produced with high content of Reclaimed Asphalt Pavement (RAP), which is recycled several times. It deals with the linear viscoela...

The road network is one of the major assets in our countries. A proper management is essential to guarantee an adequate quality of life and economic growth. This paper presents the effort undertaken for monitoring of a road section with embedded strain gauges. The experimental site is located in Corbas (close to Lyon, France). A 5 cm-thick wearing course made of BBSG (French acronym for Beton Bitumineux Semi Grenu) was placed over a pre-existing road covering an area of 6.4 mx30 m. The pavement was instrumented with six asphalt strain gauges connected to a data acquisition system called PEGASE. An experimental lab campaign was necessary for the assessment of the exact road stratification. The measurement sessions in the trial section were performed with a known loading truck at different temperatures, speeds, and trajectories. Results show a high sensibility of the measurements to the above-mentioned parameters. The mechanical behaviour of the pavement was assessed in the Viscoroute((c)) software by using both an elastic and a viscoelastic approach. It emerged that the traditional pavement design approach has some limits in predicting the pavement behaviour at high temperature. Indeed in these conditions, a viscoelastic model that takes into account the mechanic contribution of the interfaces seems to be more appropriate. This research is fruit of a collaboration between Eiffage (European, leader in construction and concessions), LPICM (Laboratoire de physique des interfaces et des couches minces), IFSTTAR (Institut Francais des Sciences et Technologies des Transports, de l'Amenagement et des Reseaux), and the University of Nottingham in the framework of the network-wide-training programme of SMARTI ETN (launched in 2017 under the Marie Sklodowska Curie Research Fellowship programme, MSCA).

This work aims at presenting a new analysis methodology for interface mechanical characterization based on axial tension test, as well as verifying the effect of the fiberglass geogrid presence on interface behavior. Tests were performed on cylindrical samples vertically cored from slabs having horizontal interfaces. In addition, this investigation aims at verifying the geogrid contribution in the tension resistance of cylindrical samples horizontally cored also having horizontal interfaces. Two different bilayered asphalt slabs were prepared to conduct the investigation: one reinforced and one unreinforced. Both are composed of the same bituminous mixture, compacted in two layers glued by emulsion tack coat made with 160/220 pen grade bitumen. Afitexinov produced the coated geocomposites used in the study, based on a knitted fiberglass geogrid of 100 kN/m tensile strength in both directions, associated with a polyester veil. The characterization was conducted through tension test at a controlled axial strain rate (2% per minute) and at two temperatures (19 and 40 °C). Two tests were performed for each temperature and each type of sample (vertically and horizontally cored) resulting in sixteen test results. The proposed methodology is successfully able to characterize the interface behavior subjected to axial tension loading. The differences in the observed results are related to the variation of the interface thickness with and without fiberglass geogrids. Concerning the horizontally cored samples, a slight increase in the tension resistance was observed for the reinforced samples at 40 °C. This difference could be associated with the fiberglass geogrid contribution.

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.

Due to emerging climate challenges, engineers are looking to replace the conventional asphalt pavements by utilizing bio-materials combined with Reclaimed Asphalt (RA). However, there is insufficient record in the literature assessing their environmental performance. This study addresses the analysis of the results obtained from a life cycle assessment exercise of asphalt pavements containing bio-materials and RA within their binder courses, developed within the BioRePavation project. The aim is to analyze the environmental benefits achieved, by means of hotspot mapping and sensitivity analysis of the most impactful factors of their lifecycles. Two alternatives are compared to a conventional asphalt pavement and recommendations on how to improve the current practices are provided. Results rank the raw material acquisition and replacement as the most impactful stages, while through sensitivity analysis, linear relationships between the impact category indicator values and the RA% used, are detected.

To improve pavement design methods, the behaviour of the interfaces between pavement layers must be precisely taken into account. This paper describes the thermomechanical behaviour of an interface in the small strain domain. Thanks to the innovative 2T3C Hollow Cylinder Apparatus (2T3C HCA), the behaviour of an interface was observed directly with 3D Digital Image Correlation (3D DIC). The studied samples were constituted of two layers of bituminous mixtures with a bitumen emulsion at the interface. From cyclic tests performed at four different frequencies (from 0.01 to 0.3 Hz) and four different temperatures (from 10 to 40 °C), the complex interface stiffnesses in the tension–compression mode and in the shear mode were obtained. The time–temperature superposition principle was verified for the abovementioned stiffnesses. Knowing a 2S2P1D (2 Springs, 2 Parabolic elements, 1 Dashpot) model of the bitumen of the tack coat, the norms of the complex interface stiffnesses were modelled with 2S2P1D models by using a SHStS (Shift, Homothety, Shift and time Shift) transformation.

Mairepav9, Proceedings of the 9th International Conference on Maintenance and Rehabilitation of Pavements, Zurich, SUISSE, 01-/07/2020 - 03/07/2020; The study reported here aims to precise the combined effect of warm mix processes and multi-recycling on the main criteria of the French asphalt mix design method. Asphalt concretes (AC) 0/10mm are produced at a semi-industrial scale for a combination of 3 recycling cycles, 3 production processes (hot, warm with additive and warm with foamed bitumen) and 2 recycling rates (40 and 70%). This combination is completed by a cycle without recycling for the 3 production processes, giving a total of 21 modalities. Compactibility, water sensitivity, stiffness modulus and fatigue tests are performed on the 21 AC produced. A principal component analysis (PCA) is then performed on the set of data obtained to extract the main trends.

To improve pavement resistance, asphalt concrete layers are bonded together with a tack coat. A new device has been developed to describe the mechanical behavior of interfaces between asphalt concrete layers. The 2T3C Hollow Cylinder Apparatus (2T3C HCA) can apply torsion and tension-compression to hollow cylinder samples composed of two asphalt concrete layers with a tack coat in between. Normal and shear stresses can be applied independently with any type of loading (monotonic or cyclic). In addition to global measurements, a local optical method, based on Digital image correlation (DIC), is used to observe the deformation of the interface. The first interface characterization results are presented in this paper.

In the rehabilitation of flexible pavements, the use of reinforcement by geogrids has substantially increased recently, aiming to extend the service life of pavements. This work evaluated the effect of fiberglass grid reinforcement on crack propagation of bituminous mixtures. To conduct the research, five different configurations of pre-notched beams constituted of two bituminous mixtures layers, with and without geogrid, were tested. Two different fiberglass geogrids, ultimate tensile strength (UTS) of 100 and 50kN/m, and emulsions as tack coat, made of bitumen pure and modify by polymer (SBS), were combined for the fabrication of three reinforced configurations. In addition, two unreinforced configurations were also fabricated. The first one was a single layer slab and the second one was bi-layered slab composed of two bituminous mixtures layers glued by a tack coat. The specimens were subjected to the four-point bending notched fracture (FPBNF) test, designed at the University of Lyon/ENTPE. A 3D Digital Image Correlation (DIC) technique was used to determine the strain field on specimen central length area during crack propagation. The results showed that the effect of geogrids was clearly noticeable when the specimen is subjected to high strain and the crack starts to propagate into the beams. DIC analysis allowed the observation of grid reinforcement effect on retarding the cracking propagation of bituminous mixtures layers.

International audience; Quantification of different effects (nonlinearity, heating, thixotropy, and fatigue) occurring during fatigue tests on bituminous mixtures is presented in this paper. A focus is given on the nonlinearity phenomenon.Continuous fatigue tests and a test with specific protocol (called fatigue tests to estimate biasing effects) were performed in tension/compression mode on cylindrical samples of the same material. The analysis of results reveals that reversible effects (nonlinearity, heating, and thixotropy) are important (more than 90% decrease at 100,000 cycles for a strain amplitude of 100 μm/m at 10 Hz) and cannot be ignored when interpreting classical fatigue tests. The nonlinearity effects respect the time‐temperature superposition principle, and they are more pronounced at “high” temperature (at the same frequency). Direction of nonlinearity curve in the Cole‐Cole axes is shown to be independent of temperature and frequency for the considered range.

Regular and long-term infrastructures monitoring is fundamental for the assessment of road network conditions and the activation of adequate maintenance measures. When it comes to embedded sensing technologies for pavement monitoring much attention is paid to measurements accuracy and their understanding. Due to the viscoelastic behavior of the asphalt mix, the road pavement response depends on time and temperature. This paper aims at developing a methodology to adjust the strains measured within the pavement to a reference temperature. This methodology is based on the mechanical characteristics of the pavement and its sensitivity to temperature variations.

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.

In this study, the thermomechanical behaviour of bituminous mixtures produced with CR by dry process was evaluated. Two bituminous mixtures were produced and tested: a reference one without CR and a second one with 3% of CR on the mixture weight. The used CR had a continuous 3/6 mm grain size distribution. Complex modulus was determined using tension/compression tests with sinusoidal loading, at nine temperatures from −25 °C to 50 °C and eight frequencies from 0.003 to 10 Hz with an imposed strain amplitude of 50 μm/m. For both mixtures, Time-Temperature Superposition Principle was validated. At high frequency/low temperatures, lower values of norm of complex modulus were found for the mixture containing CR. Tensile strength was determined using direct tensile tests on two samples at 10 °C and 3.125 × 10−2 %/min imposed strain rate.

Modal analysis is an economic and efficient test method to characterise the complex modulus of asphalt concrete. In this paper, the precision of modal analysis was evaluated by performing testing a...

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

An experimental campaign on the characterization of the tri-dimensional linear viscoelastic (3D LVE) behaviour of 2 bituminous mixtures was carried out. These 2 different mixtures were produced using the same aggregates and bitumen. As additives, two types of fillers, hydrated lime and limestone filler, were used. The goal was to evaluate the influence of hydrated lime on linear viscoelastic properties of bituminous mixtures. The linear viscoelastic behaviour of bituminous mixtures was studied using complex modulus tests (tension-compression test on cylindrical specimens) at different temperatures (from −25 to +52 °C) and frequencies (from 0.003 to 10 Hz). Sinusoidal cyclic loadings of 50 µm/m axial strain amplitude were applied. In addition to axial stress and axial strain, radial strains were also measured. The complex modulus E* and the complex Poisson’s ratios ν* were then obtained and the three-dimensional (3D) LVE behaviour (with isotropy hypothesis) was then completely described. The Time-Temperature Superposition Principle (TTSP) was verified with good approximation. The same values of shift factor were obtained for uni-dimensional (1D) and tri-dimensional (3D) conditions. The 2S2P1D model (3D) developed by ENTPE team was used for modelling linear viscoelastic properties of the two mixtures. Effect of hydrated lime is discussed.

Ballast deterioration, under dynamic loads, remains an important issue on high-speed tracks that can lead to high maintenance costs. This ballast deterioration leads to settlements. Several studies have shown that these settlements were linked to high accelerations produced in the ballast by high-speed train (HST) passages. The solution with bituminous underlayment was used since 1980s in several countries like United States, Italy, Spain, especially on high-traffic and high-speed lines (HSL). In France, the interest in this technique is recent. Following the East European HSL satisfactory behavior, a layer of asphalt concrete was used under the ballast layer of the Bretagne-Pays de la Loire (BPL) HSL. It is intended, in addition to the schedule savings and the protection of the subgrade during the construction phase, to reduce acceleration amplitudes produced at the passage of HST, to ensure moisture stability in the subgrade and thereby to decrease the maintenance costs of the tracks. BPL HSL includes 105 km of innovative track with an asphalt concrete (GB) ballast sublayer, and 77 km with a granular layer under the ballast (UGM). Out of the instrumented sections of the BPL track, 3 sections are constructed with GB subballast layer and one with a layer of UGM as a subballast layer. A total of 127 sensors that includes accelerometers, anchored displacement sensors, temperature and humidity probes, and extensometers are used. Sensors are placed at various positions and depths in the track structures. Data were first acquired during a speed up test phase, under controlled conditions, with the same train passing at speeds ranging from 160 to 352 km/h. This paper presents the different sensors used for the instrumentation as well as the acquisition system installed to collect all measurements. Data treatment and processing is explained in details. Finally, results obtained for different speeds are presented, with a focus on accelerometer and anchored displacement sensor measurements, on two sections, allowing, among others, comparisons between the response of structures with and without asphalt concrete. The role of the GB, as a subballast layer, in damping the vertical displacement of the sub ballast structure and reducing the accelerations peaks in the ballast layer for ballasted tracks is demonstrated.

Three innovative environmentally friendly pavement materials, designed with 50% of Reclaimed Asphalt and three different biomaterials (2 bio-additivated bitumens and 1 bio-binder), were produced in an industrial plant. These mixes were tested in lab and also at full scale using an Accelerated Pavement Test facility. The asphalt mix viscoelastic properties were measured in lab and their intrinsic viscoelastic response were simulated. These rheological models are used to simulate the pavement mechanical response using both elastic and viscoelastic multilayer codes. Hence, full scale measurement performed during the full scale test at an early stage (without damages) can be compared with these simulations. The overall prediction accuracy, when all the signals are considered, is between 4% and 8% for all materials. It can be concluded that material characterisation in lab as well as the selected models are well adapted to simulate actual loading state under a moving load, even for these non-conventional mixes. For temperatures lower than 25°C, elastic modelling appears to be sufficient for pavement structural design with the innovative materials tested here.

Recycling of asphalt has become a well-established practice in many countries, however the road pavement industry remains a bulk consumer of extracted raw materials. Novel solutions that find root in circular economy concepts and life-cycle approaches are needed in order to enable optimisation of infrastructure resource efficiency, starting from the design stage and spanning the whole value chain in the construction sector. Itis within this framework that the present study presents a full-scale validation of asphalt mixtures specifically designed to ensure durability of flexible road pavements and at the same time enabling the reuse of reclaimed asphalt pavement (RAP) through the incorporation of bio-materials as recycling agent. These bio-recycled asphalt mixtures have been first designed in laboratory and subsequently validated in a real scale experiment conducted at the accelerated pavement testing facilities at IFSTTAR. Four pavement sections were evaluated: three test sections with innovative bio-materials, and a reference section with a conventional, high modulus asphalt mix (EME2). Two tests were realized: a rutting test and a fatigue test and for each of them the evolution of bio-recycled asphalt mixtures properties as well as the pavement deteriorations were recorded and studied. Evolution of the bio-asphalt mixtures was monitored for a 5 months period after paving by a bespoke nondestructive micro-coring, extracting and recovering methodology developed at the Western Research Institute (WRI). The structural health of the pavement sections was monitored through periodic falling weight deflectometer (FWD) as well as with strain gages and temperature sensors. As a result the three tailored bio-asphalt mixtures performed similarly or better than the control mixture, both in terms of property evolutions and durability.

International audience; Eiffage developed a high-performance bituminous mixture known as GB5. It is based on aggregate optimization method. This paper presents the results of a research project checking whether, in the small strain domain, this type of mixture behaves like the more conventional asphalt mixture GB3 currently used as a base layer in French bituminous pavements. Three-dimensional complex modulus tests are performed on GB5 and GB3, two hot mixtures asphalt (HMA) made with the same bitumen but produced with different aggregate skeletons. Tension-compression sinusoidal testing is applied to the specimens over a wide frequency and temperature range. Both axial and radial strains are monitored, thereby allowing the computation of the complex Young's modulus and complex Poisson's ratios. From the experimental results, the time-temperature superposition principle (TTSP) is verified for both complex Young's modulus and complex Poisson's ratios in two directions. The obtained shift factors and normalized complex modulus curves for the two mixtures indicate that the bitumen phase drives the viscoelastic behaviour of the asphalt mixture, regardless of the granular skeleton. The effect of air-void content on the static, glassy, and characteristic time values of modulus and Poisson's ratios, which is obtained from simulation using a linear viscoelastic model with two springs, two parabolic elements, one dashpot, is analyzed. The anisotropic properties of the two mixtures and the reproducibility between the two laboratories is also checked.

Recently, the use of geogrids as bituminous pavements reinforcement has increased in pavements construction and rehabilitation, mainly to avoid reflective cracking. One major research topic is to characterize the mechanical behaviour of actual reinforced pavement structures, from laboratory experimentation and take it into account for the design. This paper aims at presenting a methodology for the determination of the Interface Linear Viscoelastic (LVE) behaviour of specimens reinforced with geogrids. This method is based on a tension-compression test on cylindrical sample, classically used for complex modulus tests. A geogrid produced by Texinov was glued with tack coat, which constitute the studied interface. This geogrid is composed by fiberglass filaments and polyester veil, both coated with emulsion. Axial cyclic tests at controlled strain mode of loading (tension-compression) were performed on the same bituminous mixtures samples with and without geogrid. The experimental data was fitted using the 2 Springs, 2 Parabolic Elements and 1 Dashpot (2S2P1D) model both for the mixtures and for the interface. The results indicate that the proposed methodology can successfully provide the interface LVE behaviour.

The phenomena of packing and wear of the ballast, under dynamic stresses lead to high frequencies and high maintenance costs. It has been demonstrated that the settlements in the ballast were linked to the high accelerations produced in this layer by the passage of high-speed trains. The solution with bituminous underlay was used since the 1980s in several countries like the United States, Italy, Spain, especially on high-traffic and high-speed lines (HSL). In France, the interest in this technique is recent. Following the satisfactory behavior of the East European HSL, a layer of asphalt concrete was made under the ballast layer on a high scale lane, the Bretagne-Pays de la Loire (BPL) fast lane. It is intended, among other things, to reduce the amplitude of the accelerations produced at the passage of the HST. The HSL BPL has 105 km of innovative track with an asphalt concrete (GB) sublayer under the ballast, and 77 km with a granular under layer. In order to study the dynamic responses of these different structures and to understand the effect of the different layers on the dynamic response, four sections were instrumented (3 with asphalt concrete, and one on a standard granular structure) using, among others, accelerometers, strain gauges, temperature probes, etc. More than 100 sensors have been installed on the structure in different positions and depths. The acquisition of the data is made during the speed up test phase under controlled conditions with the same train passing with speeds going up from 160 to 352 Km/h. In a later phase, measurements of all the sensors will be treated under actual traffic. The BPL lane is subjected to commercial traffic since July 2017. The main idea of the project and the expected results for the first phase are to analyze the measurements in the database created and determine the responses of the different sections and the variations of the various parameters measured: Vertical displacements, accelerations at different levels, horizontal deformations in the bituminous layer, etc. In this paper, a description of the railway track “Bretagne pays De la Loire”, the instrumentation of the different sections and the acquisition system are detailed. The processing and treatment method used for the registered data is explained. The variation of the speed of the trains is also expected to be carried out in this paper to evaluate the behavior of the structures in section 4 with bituminous underlayment in terms of vertical acceleration.

Pavement structure lifetime can be dramatically reduced in case of poor bonding between layers. Study of interfaces between pavement layers is essential to improve pavement durability. An innovative and new experiment named 2T3C Hollow Cylinder Apparatus (2T3C HCA) has been implemented to characterize interface performances. In this test, combined compressive (or tensile) stress and shear stress can be independently applied to the interface. The tested samples are hollow cylinder samples (12 cm height, 17.5 cm external diameter and 12.5 cm internal diameter) constituted of two bituminous pavement layers separated by an interface made with a tack coat. Samples representing a pavement structure are made in laboratory using the French wheel compactor. Digital Image Correlation (DIC) is used to obtain displacements in the three dimensions on the surface of samples. It makes it possible to locate the interface and observe its deformation. In this paper the 2T3C HCA device is presented and first results on bituminous mixtures behaviour and on interface behaviour are presented.

This chapter focuses on the three-dimensional linear viscoelastic (3D-LVE) behaviour of bituminous mixtures and in particular on the measurement and modelling of the complex Young’s modulus and Poisson’s ratio (PR). In the first part of the chapter, the LVE definition of PR is reviewed and experimental measurements of the LVE PR carried out over the last 40 years are summarised. The second part of the chapter is devoted to the description of a RILEM round robin test (RRT) organized by Task Group 3 (TG3) “Mechanical testing of bituminous mixtures” of RILEM TC 237-SIB. Within the RRT uniaxial cyclic (sinusoidal tension/compression or haversine compression) tests at different temperatures and frequencies were carried out on cylindrical specimens cored from laboratory compacted slabs. Two types of bituminous mixtures, GB3 (continuously graded) and GB5® (gap-graded), were analysed. Five laboratories participated in the RRT, each laboratory measured axial and transverse (or diametral) strains using different sensors and configurations. In particular, transverse strain was measured along two orthogonal directions in order to evaluate the effect of compaction-induced anisotropy on PR. Results confirmed that PR of bituminous mixtures is a complex function of temperature and frequency and that the time-temperature superposition principle can be applied (for absolute value and phase angle). For the studied mixtures the norm of the complex PR ranged between 0.22 (low temperatures/high frequencies) and 0.60 (high temperatures/low frequencies) whereas the phase angle was less than 6°. A small difference (less than 0.05) was found between measurements carried out in two orthogonal directions. This small difference is probably related to measurement accuracy and not to the anisotropic behaviour of the material. Comparison of data between the different laboratories, which could not be performed at exactly the same temperatures and frequencies, was performed using a common reference given by the 3-dimensional formulation of the 2S2P1D linear viscoelastic model. This model provides a good simulation of experimental data. Based on close results from all participating laboratories, it is possible to conclude that cyclic uniaxial test could be a good candidate to become a standard test for evaluating the 3D-LVE behaviour of bituminous mixtures.

El interés en la utilización de bio-materiales en ingeniería de pavimentos ha crecido significantemente en las últimas décadas debido a la conciencia ambiental sobre el uso de recursos naturales no renovables. En este artículo, se utilizan bio-materiales para recuperar las propiedades iniciales del betún envejecido presente en mezclas con alto contenido de asfalto reciclado (RA). Para ello, se ha estudiado y comparado el comportamiento de dos bio-materiales con betunes convencionales y betunes modificados con polímeros. Con este objetivo, se fabricaron mezclas de bio-materiales y betún reciclado simulando mezclas asfálticas con 50% de contenido de reciclado. El efecto rejuvenecedor de los bio-materiales se ha evaluado y comparado con el efecto rejuvenecedor de ligantes convencionales mediante el cálculo de las distribuciones de peso molecular aparente y diferentes parámetro reológicos. Los resultados muestran el poder rejuvenecedor de los bio-materiales, poniendo de manifiesto su potencial para usarse como ligantes vírgenes en mezclas asfálticas con alto contenido de reciclado.

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...