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The phase angle (φ) has long been recognized as a powerful tool to detect variations in asphalt binders’ chemistry and microstructure. A recent study applied unsupervised multivariate approaches to uncover hidden pattern structures in data sets and settled the most relevant reduced frequency to investigate the evolution of the phase angle master curve with aging. Considering that study’s findings, this paper revisits the δ-method—that is, an approach that estimates the apparent molecular weight distribution (AMWD) of a given asphalt binder based on its rheology—and proposes a simple indicator that quantifies the incidence of asphaltene molecular agglomeration named Molecular Agglomeration Index (MAI). Laboratory- and field-aged binders were tested and a limiting value for MAI indicating an increased binder cracking susceptibility is established in agreement with other failure criteria found in the literature.

T The roadway networks have been played a vital role in the development of all countries. The assessments of pavement conditions during their service life are therefore decisive to maintain the stable performance of the network. From this point of view, pavement instrumentation allows monitoring pavement conditions continuously and without traffic interruption. The study aims to illustrate the effectiveness of embedded strain gauges and temperature probes to follow the pavement responses with different traffic speeds, traffic loads and temperature conditions. The longitudinal strain signals are then examined with regards to representative parameters of the loading times and strain amplitude. The results show that the traffic load levels and asphalt temperature are directly responsible for the change of strain amplitudes, while those have almost no impact on loading times. Numerical simulations are also introduced to validate the applicability of both layered elastic and viscoelastic models to the strain signals observed in the field.

This paper presents an investigation on the permanent and resilient deformation behaviour as well as the shear and physical properties of different RCA, sourced from demolished buildings (RCAB1 and RCAB2) and concrete pavement (RCAP). Monotonic triaxial tests and repeated load triaxial tests (RLTT) were performed to determine respectively their failure resistance and the cyclic behaviour, modelled with the Boyce model and the DBGSP model. In addition, the physical properties and water absorption kinetics of aggregates were studied and compared with the existing standard. The results indicated that all RCA have admissible physical properties and can be used in pavement base and subbase layer. However, the RLTT revealed that the use of concrete wastes with low strength and containing high amount of rounded particles (RCAP in this study) can lead to poor performance of pavement, which should be limited in the pavement construction.

This paper presents an Acoustic Emission characterisation of the damage behaviour of asphalt concrete subjected to bending fatigue loading. An experimental campaign is carried out on an old asphalt...

Bitumen aging has long been recognised as one of the primary factors that affect pavement’s durability. The amount of rheology-based indexes proposed to track the evolution of bitumen aging level u...

This research was carried out to determine the rheological parameters of lateritic soils in order to contribute to the improvement of the technical documents used for pavement design in tropical Africa. The study is based on the loading repeated of cyclic triaxial tests (LRT) performed at University Gustave Eiffel (formerly Institut Francais des Sciences et Technologies des Transports de l’Amenagement et des Reseaux (IFSTTAR)) in Nantes with the application of the European standard EN 13286-7: 2004 [1]. The tests were performed at constant confinement stress and using the stepwise method to determine the resilient axial () and radial () deformation as a function of the axial and radial stresses. Four gravel lateritic soils from different sites selected in Burkina Faso and Senegal were the subject of this research for the triaxial tests. These materials have a maximum diameter of 20 mm and a percentage of fines less than 20%. The LRT tests were carried out on samples compacted at three moisture contents (wopm - 2%, wopm and wopm + 2%) and at 95% and 100% of optimal dry density (γdopm). Test results showed that the characteristic resilient Young’s modulus (Ec) of gravelly laterites soils depends on the compacted water content and the variation of the grains size distribution (sand (o 20%), mortar and sand (Sindia and Lam-Lam) are more sensitive to variations in water content. The presence of water combined with the excess of fines leads to a decrease in modulus around 25% for Lam-Lam and 20.2% for Sindia. Materials containing a low percent of fines, mortar and sand (Badnogo and Dedougou) behave differently. And the resilient modulus increases about 225.67% for Badnogo and 312.24% for Dedougou with the rise of the water content for approximately unchanged the percentage of fines, mortar and sand. Granularity therefore has an indirect influence on the resilient modulus of the lateritic soils by controlling the effects of water on the entire system. Results of statistical analysis and coefficients of correlation (0.659 to 0.865) showed that the anisotropic Boyce’s model is suitable to predict the volumetric () and deviatoric strain () with stress path (Δq/Δp) of the lateritic soils. The predicted Er resilient Young’s modulus from anisotropic Boyce’s model varies according to the evolution of the bulk stress (). A correlation around 0.9 is obtained from the power law model.

International audience; In this paper we present the results of the national French project SolDuGri dealing with pavement reinforcement by glass fiber grids. In this project, an accelerated pavements test (APT) was performed on 6 pavement sections to evaluate the in situ performance of the reinforcement on their lifetime. The tests consisted in building test sections with four different types of grids, and two different compacted asphalt con-crete layers above (hot mix asphalt and warm mix asphalt). A total number of 2.2 mil-lion of 65 kN dual wheel loads was applied on these pavement sections and their per-formance was evaluated using in situ instrumentation, pavement monitoring tests and laboratory tests on recovered specimens. In parallel and in addition to static debond-ing tests, four points bending (4PB) fatigue tests were carried out in the laboratory on reinforced and non-reinforced beams. Two reference glass fiber grids were used, one with a high tensile strength of 100 kN/m and one with a lower tensile strength of 50 kN/m. Laboratory fatigue tests were performed with 2 positions of the rein-forcement in the beams to evaluate the effect of reinforcement for any position of the grid in the beam. Based on the results of the 4PB fatigue tests, a methodology is proposed to evaluate the lifetime of the full-scale test sections, and the predictions are compared with the results of the APT experiment showing good agreement.

The design and durability of high-speed railway lines is a major challenge in the field of railway transportation. In France, 40 years of feedback on the field behavior of ballasted tracks led to improvements in the design rules. However, the settlement and wear of ballast, caused by dynamic stresses at high frequencies, remains a major problem on high-speed tracks leading to high maintenance costs. Studies have shown that this settlement is linked to the high acceleration produced in the ballast layer by high-speed trains traveling on the track, disrupting the granular assembly. The “Bretagne–Pays de la Loire” high-speed line (BPL HSL), with its varied subgrade conditions, represents the first large-scale application of asphalt concrete (GB) as the ballast sublayer. This line includes 77 km of conventional track with a granular sublayer of unbound granular material (UGM) and 105 km of track with an asphalt concrete sublayer under the ballast. During construction, instruments such as accelerometers, anchored deflection sensors, and strain gages, among others, were installed on four sections of the track. This paper examines the instrumentation as well as the acquisition system installed on the track. The data processing is explained first, followed by a presentation of the ViscoRail software, developed for modeling railway tracks. The bituminous section’s behavior and response is modeled using a multilayer dynamic response model, implemented in the ViscoRail software. A good match between experimental and calculated results is highlighted.

The objective of this study is to assess the impact of climate on the performance of bituminous pavements with two different methods, and then to examine their impact on actual design scenarios. Three climate cases were selected for the comparisons involving the effect of temperature: one in France (Bordeaux) and two in the United States (Seattle and Phoenix). The case of an experimental site in Québec was also used for comparisons concerning consideration for seasonal variations in ground bearing capacity. The analyses were based on French (Alizé-LCPC) and US (AASHTOWare Pavement ME Design) mechanistic-empirical pavement design approaches. Interesting features of the two design methods are outlined and their fatigue cracking models are linked together. The results of the study highlight the importance, for design purposes, of the empirical fatigue equations as a function of temperature. For the site studied in France, the design results in terms of AC base layer thicknesses indicate that both methods show a similar trend with an increase in temperature. For the site in Québec, which is submitted to severe freeze/thaw cycles, the results show that taking temperature and moisture into account for unbound materials leads to a prediction of more severe permanent deformation.

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.

Bitumen aging increases the risk of pavement cracking. A good understanding of this phenomenon is crucial for designing long-lasting pavements. In this context, this paper presents a review of the relevant literature on neat bitumen aging. A broad set of indexes often used to estimate the aging level and end-of-life criteria of bitumen are analyzed and discussed.

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.

Cet article présente les résultats d’une première investigation expérimentale dont l’objectif est de suivre le processus d’endommagement sous un chargement de fatigue mécanique par la technique de l’Emission Acoustique (EA). Les éprouvettes de forme trapézoïdales sont testées en flexion 2 points à 10°C-25Hz et une amplitude de déformation de 175 µm/m. Les résultats mécaniques sont présentés en terme d’évolution de module complexe et d’énergie dissipée. Les critères conventionnels de rupture basés sur la diminution de module ( et ) et sur approche énergétique ( ) sont comparés avec les résultats acoustique. Un seuil d’endommagement est détecté sur la base l’évolution des hits au cours de l’essai. Des critères basés sur la variation de l’activité acoustique pendant l’essai ont été proposés et comparés aux critères mécaniques., Academic Journal of Civil Engineering, Vol 38 No 2 (2021): Special Issue - Diagnobéton 2021

Reclaimed asphalt pavement (RAP) arises from the demolition of asphalt road layers. The Optimal Recycling of Reclaimed Asphalt Pavements Project concerns the cold recycling of 100 % RAP without binder addition in base and subbase layers of low-traffic roads. In this context, a test program was performed with Rhine region materials to evaluate the impact of the mastic coating of untreated RAP. A source of reclaimed asphalts with 4.4 % of bitumen is tested before (RAP) and after binder extraction (RAP-BE) and then is compared to an unbound granular material (UGM) with a similar particle-size distribution. Repeated load triaxial tests were conducted at several frequencies to study the permanent and resilient behaviors. The results show that the RAP before binder extraction and the UGM present similar permanent behaviors, while the aggregates without binder reveal low strains. Concerning the resilient phase, the RAP and the RAP-BE show similar levels of strains, but the resilient moduli of the UGM are significantly lower than those of the RAP. From the experimental results, the nonlinear elastic Boyce model was fitted and brings out a highly anisotropic mechanical behavior of the RAP. Finally, the RAP shows a frequency-sensitive viscous behavior because of the bitumen in the mastic, while the effect of the frequency is negligible for the RAP-BE.

The applied pavement design procedures differ from country to country within Europe. Especially the use of cold recycling materials which is handled similar to hot-mix asphalt (HMA) in the most available guidelines isn’t sufficient researched. To verify developed procedures, practical trial sections are indispensable. Within this study cold recycled asphalt base layers (CRAB) were assessed according to the German procedure for monitoring and evaluation of road surface conditions. It can be concluded, that the general applied empirical design approach, in which the CRAB layer thickness is increased by 50 % compared to a HMA base will result in a feasible pavement structure. In general, the re-designing of the sections according to various national empirical pavement design approaches partly results in high differences for same layer types.

The work presented in this paper is part of an interdisciplinary research project named SolDuGri dealing with the reinforcement of asphalt concrete pavements using glass fibre grids. We present in ...

International audience; The Optimal Recycling of Reclaimed Asphalts in low-traffic Pavements (ORRAP) project concerns a cold recycling of 100% Reclaimed Asphalt Pavement (RAP) without binder addition, in base and subbase layers of low-traffic pavements. The mastic coating of aggregates induces a viscoelastic behaviour and changes the resilient modulus with frequency and temperature. This modulus is obtained with repeated load triaxial tests and is a key element for pavement design. In this context, this paper presents a numerical alternative to predict this influence with a discrete approach. Contact Dynamics (CD) simulations are used to reproduce the resilient modulus test on a set of rigid spherical particles with a viscoelastic contact, based on the Burgers’ model. The tests were carried out with cylindrical samples at several frequencies for two temperatures (20 °C and 40 °C). The proposed model is calibrated in a given range of temperatures and frequencies regarding the experimental data, and then used to predict resilient modulus values at unreachable frequencies in the laboratory, with one set of parameters for each temperature. Finally, using the Williams-Landel-Ferry (WLF) equation, a master curve of resilient modulus at 20 °C as a function of the frequency was established. The Time-Temperature Superposition Principle (TTSP) reveals that the values at high frequencies and 40 °C correspond to the data at low frequencies and 20 °C.

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.

This volume gathers the latest advances, innovations, and applications in the field of accelerated pavement testing (APT), presented at the 6th International Conference on Accelerated Pavement Testing, in Nantes, France, on September 27-29, 2021. Discussing APT, which involves rapid testing of full-scale pavement constructions for structural deterioration, the book covers topics such as APT facilities, APT of asphalt concrete and sustainable/innovative materials, APT for airfield pavements, testing of maintenance and rehabilitation solutions, testing of smart and multi-functional pavements, data analysis and modeling, monitoring and non-destructive testing, and efficient means of calibrating/developing pavement design methods. Featuring peer-reviewed contributions by leading international researchers and engineers, the book is a timely and highly relevant resource for materials scientists and engineers interested in determining the performance of pavement structures during their service life (10+ years) in a few weeks or months.

Pervious concrete use has increased since more than a decade thanks to its main feature of high water permeability. However the use of this material is still limited to light traffic areas, like car parks or walkways in urban areas. Recently LafargeHolcim Research Center has developed an innovative concept of concrete pavement structure using this type of material for heavy traffic highways. An ultra-thin innovative pervious concrete layer is laid directly (wet on wet) on top of an optimized concrete layer just after its placement. This innovative solution allows ensuring both structural performance and surface characteristics for road users in terms of safety, riding comfort and aesthetic. In order to evaluate the actual performance of this innovative pavement structure, an accelerated pavement test (APT) was carried out using the FABAC heavy traffic simulator of IFSTTAR in Nantes. A total of five million cycles of 6.5 tons half-axle load were applied. Structural performance and lifetime of the pavement were evaluated by comparison with a design process using the French-standard-design-software called Alize-LCPC. The evaluation of the bonding strength at the interface between the pervious wearing course and the structural concrete bottom layer showed good durability throughout the entire test, which could allow possible consideration of the surface layer in the whole pavement design process. Finally, dynamic friction tests conducted on the innovative wearing course during the APT allowed to evaluate and predict the evolution of its skid resistance throughout the pavement lifetime.

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.

The aim of this study is to develop a method for identifying asphalt pavement layer properties based on readings from accelerometers and geophones that are embedded near the ride surface. These sensors are relatively small in size and easily embeddable, making them an ideal choice for wide-area applications in the live transportation network. As a first step, a section within the IFSTTAR accelerated pavement testing (APT) facility was instrumented with accelerometers and geophones; also installed was an anchored displacement sensor to serve as a reference/validation device. The APT facility offers the ability to control the loading configuration and intensity, travel speed, and wander (i.e., lateral offset) position relative to the sensor locations. Thus, it becomes possible to isolate the task of property identification through inverse analysis from other real-world complications. The paper commences by describing the experimental setup, and presenting some raw sensor measurements during a single pass of the APT’s wheel carriage. Then, assuming a layered-elastic model, a method is proposed and demonstrated for estimating the pavement moduli. The method is based on best-matching measured velocities and accelerations for the geophones and accelerometers (respectively), with the model predictions- without integrating the signals to convert them into deflections. Very good match is obtained for the sensor readings, and the inferred moduli closely agree with reference values. This outcome means that there is great potential in building a pavement condition monitoring system with near-surface accelerometers and geophones.

In accelerated pavement tests performed at IFSTTAR, it is common to perform continuous deflection measurements under applied loading, using deflection sensors. These sensors, which consist of an LVDT attached to a rod anchored at a depth of about 4 m, are difficult to install and relatively expensive. In this project, the possibility of using geophones or accelerometers, as an alternative method to measure pavement deflections has been investigated. Geophones and accelerometers measure respectively the vertical velocity and the vertical acceleration, and by integrating their signals, it is possible to calculate the deflection. Two types of geophones, and two types of accelerometers have been selected for the study. They have first been submitted to laboratory tests, on a vibrating table, simulating pavement deflections signals. Based on these tests, suitable signal treatment methodologies, to filter and integrate the signals, to obtain reliable deflection measurements, have been developed. The sensors have then been installed in an experimental pavement section, tested on the IFSTTAR APT facility. Deflections obtained with the geophones and accelerometers have been measured under different load conditions. The obtained values were in good agreement with those measured with a reference deflection sensor.

Accelerated pavement testing (APT) is well known as a very effective way to investigate the actual behaviour of pavement structures. Feedback from the test can be obtained in a couple of months through measurements and monitoring made during the experiment. Among them, pavement surface cracking is one of the most important parameters for the evaluation of experimental pavement performance. Generally, crack monitoring during APT tests is still carried out manually for every specific loading period. This classical approach is time-consuming and interesting information may be lost if a measurement is missed. For this reason, a Rapid and Continuous Imaging (RCI) technique has been developed and tested at IFSTTAR, for the monitoring of crack development on the pavement surface during APT experiments. The principle of this technique consists in taking images of the experimental pavement surface continuously along the test track, at intervals depending on the moving speed of the heavy traffic simulator, i.e. the road fatigue carrousel. A crack map, representing an overview of visible cracks on a pavement section can then be rapidly created using an ad hoc image processing tool. The application of this pavement crack mapping technique for crack monitoring on an asphalt pavement during a recent APT experiment showed interesting results.

Road construction companies are developing innovative road solutions which integrate new functions, such as the ability to generate energy. The authors focus here on the use of road solutions harvesting solar and geothermal heat energy. In 2014, PIARC’s report entitled “Alternative solutions for fossil fuels for the road system” listed the main limitations blocking the development of these innovations among which the resistance to traffic. The authors present a recent accelerated test at scale one of a pavement that incorporates geothermal tube networks in the first 10 cm of the pavement. The main goal is to assess the impact of the tubes on the durability of the overlay and structure. The first part of the paper describes the experimental site, located at the toll station of Saint Arnoult, next to the A10 highway, near Paris. It is composed of 4 trial sections. Tubes were buried at construction stage at 2 different depths. The second part presents the experimental setup: (i) the FABAC traffic simulator used for the tests and (ii) the survey methods used to follow the evolution of the structures. The third part present the measurements made during the tests and the fourth part is dedicated to the analysis of the results and conclusions.

Pavement instrumentation has recently become an important aid-tool of pavement monitoring for the assessment of pavement structural behaviour. Classically, measurements on instrumented pavements are performed on site, under known load conditions: the response of the pavement is recorded under the passage of a reference vehicle, with known axle loads. In such conditions, data interpretation and modelling of the pavement are relatively easy. However, on site measurements are time consuming and costly to perform, because they require using a dedicated vehicle, and closing the lane to traffic, which is not easy on a heavily trafficked motorway. This paper presents an experiment, where an instrumented bituminous pavement motorway section has been followed by remote monitoring, under normal traffic. The section, instrumented with strain gages, temperature probes and geophones, has been monitored continuously during 18 months. Signal sorting procedures have been developed for reducing the quantity of recorded data, and for analysing the structural response of the pavement, under highly variable loading conditions, and are presented and discussed. The results of the strain gage measurements, made at different depths within the pavement, have shown that the response of the pavement presents large variations with temperature, and in particular, that the degree of bonding between pavement layers can decreases at high temperatures, leading to sliding between pavement layers. The mechanical response of this instrumented pavement section has been analysed using a classical multi-layer linear elastic pavement model and also a viscoelastic model. The best predictions have been achieved with the viscoelastic model. Different approaches for describing the behaviour of pavement layer interfaces have also been evaluated.

This paper presents a new method for analyzing experimental data stemming from the Two-Point Bending (2 PB) fatigue test conducted on French standardized trapezoidal specimens, in accordance with the European standard EN 12697-24. These tests were performed on an asphalt mix specimen sawn from an in-service road pavement, adopting a loading frequency of 25 Hz and a target temperature of 10 °C. The Acoustic Emission (AE) technique was implemented to monitor the damage and failure processes during fatigue. The fatigue life, defined as the critical number of loading cycles inducing specimen failure, is investigated herein according to several methods, including a normalized criterion, models proposed in the literature, experimental fitting, and Acoustic Emission activity analysis. First, based on the AE analysis, new damage and failure criteria are proposed (Damage Initiation and Failure Propagation Thresholds). In a second step, the mechanical behavior is fitted, in terms of strain, force, stiffness modulus, and phase angle, using four functions, namely: a polynomial function, a continuous Fourier series, a sum of sine functions, and a Gaussian function. After the fitting process, the first derivative is calculated and the singular points of the curves are detected and discussed. Lastly, a phenomenological analysis is carried out in order to understand the damage and failure process stages.

A portion of the lane reserved for slow vehicles on a motorway was totally rebuild of the A10 Motorway in the West of Paris. Four sections have been instrumented using classical strain gage sensors, placed at different depths within the pavement (subgrade, cement-treated subbase, and bituminous base) and temperature sensors. A fifth section is equipped with a more innovative instrumentation including geophones and temperature sensors, coupled with a remote data acquisition system. The purpose of this paper is to present the monitoring of these experimental sections since 2011. Strain gage measurements are used to develop a mechanical model of the pavement structure, to evaluate the modulus of the different pavement layers, as well as their evolution with time. The results confirm the good performance of the inplace recycled subbase. Geophones are very sensitive sensors measuring vertical displacement velocity. Different methods for the processing of these measurements are proposed in order to monitor pavement deflections and identify and classify truck silhouettes.