The aim of this MACADAM research project is to develop a software dedicated to pavement surface layer design. The resulting tool will enable engineers to mitigate pavement surface damage due primarily to traffic loading. In France, a tremendous budget is allocated to pavement maintenance, upwards of 10 billion euros for urban areas alone. The extent of the underlying economic and environmental impacts, plus the lack of a rational method for designing such a maintenance system, has made this issue a key societal challenge. The first step to bringing tyre-pavement contact modelling in line with actual field measurements makes use of a tribological approach; this objective can be quickly achieved by means of a joint research laboratory effort (involving LaMCoS for contact mechanics and GEMH for pavement mechanics and engineering). Three main work packages can be defined: 1) tyre-pavement modelling (Work Package 1, WP1); Accelerated Pavement Testing (APT) validation (WP2); and design and production of a traffic simulator (WP3). Tyre-pavement contact modelling, including thermo-visco-elasto-plastic behaviour in the pavement surface layer, will lead to the software "SAMRoad", which simulates actual tyre-pavement contact in order to derive stress and strain fields in the first layer. Several test identifications, relying on both monotonic and cyclic loading, will be necessary for APT material characterisation. Pavement modelling with SAMRoad will yield the surface layer rut depth. The main advantage of a semi-analytical model is to run a simulation in little time compared to the 3D finite element model, which necessitates lengthy computations. SAMRoad will incorporate tangential forces, thus making it possible to consider braking, acceleration and turning configurations. The experimental Work Package will entail an APT assessment of the SAMRoad model. The current construction of a pavement pit 3 m by 8 m by 2 m deep inside the new research facility will serve to test a pavement 1.90 m wide by 8.0 m long. The FABAC traffic simulator will be run under both rutting and fatigue cracking conditions. The APT results will then be compared with SAMRoad model output. This WP will be limited to a rutting/cracking assessment of SAMRoad in the case of traffic without any tangential loading. Work Package 3 will address the tangential loading for a singular pavement area (e.g. slope, turn, rest area). For this WP, we will be required to study and build a specific simulator once the MACADAM project has been launched. This initial simulator will be designed at the lowest cost, hence a second-hand truck axle will be used. The edge of the pavement pit will be built to accommodate the simulator frame anchor so as to apply horizontal and vertical loads on the truck axle. The axle will be guided by a large central beam to enable round trip loadings on a 4-meter track. Upon completion of the project, SAMRoad will be capable of designing surface layers according to the lifetime calculation with rutting and/or fatigue cracking criteria. The MACADAM simulator will be capable of simulating damage for a single pavement area (e.g. turn, braking, slope). Pavements will be the first case studied and the focus of a demonstrator for 30,000 roundabouts across France. A backup solution is possible, as the MACADAM simulator can be replaced by several APT with FABAC, to obtain a comprehensive rutting validation.

Maintenance of road infrastructures represents a considerable socio-economic challenge in a context where budgets of asset managers are increasingly restricted. To optimize the maintenance of these infrastructures, it is necessary to develop monitoring and diagnosis methods to estimate reliably their residual lifetime. It is one of the objectives of the French “Road National Observatory - https://www.idrrim.com/ONR/” launched in January 2016 by the representatives of the road infrastructures sector. The MOVEDVDC project aims at the characterization of residual mechanical properties of bituminous materials in base layers, and their evolution over time, two inputs which are necessary to the calculation of pavement lifetime, and pavement maintenance solutions. The important targets are: - To define a methodology for assessing ageing and damage of bituminous materials, based on the analysis of materials sampled on field and on studies on materials aged in laboratory conditions, - To define ageing indicators used for the assessment of materials lifetime, - To propose, form these studies, models to predict mechanical properties of aged materials (in particular complex modulus and fatigue resistance) and their evolution, to be implemented in pavement lifetime calculation. This is an important output for the dissemination of the project. MOVEDVDC complements the National project DVDC (Pavement lifetime – www.dvdc.fr) which is a collaborative research project launched in June 2016, aiming at the development of tools and methods for the evaluation and maintenance of old pavements. The DVDC project brings together nearly forty partners of the road infrastructures sector: private companies, asset managers, research organizations. MOVEDVDC adresses one of the most important technical and scientific challenges identified in the DVDC project, which is the assessment of ageing and damage state of bituminous materials. The research program of MOVEDVDC is structured around 6 main tasks: (i) coordination, (ii) selection and characterization of experimental sites, (iii) analysis of binder behaviour, (iv) analysis of mixture behaviour, (v) modelling and calculation of pavement residual lifetime and (vi) dissemination. It is realized by a consortium constituted of 4 academic organizations (ESTP, IFSTTAR, INSA Strasbourg and University of Limoges) and 4 private companies (Eiffage Infrastructures, Eurovia, Malet, Total), which bring together strong scientific skills, a strong link to the field, and important laboratory testing facilities. Two major outputs are expected from this project, which will constitute important inputs for the establishment of operational technical guidelines shared with all the stakeholders: - A methodology for the characterization of aged and damaged bituminous materials, at binder and mixtures scales, - A new approach for describing the mechanical performance of these aged materials in the calculation of pavement lifetime and design of pavement maintenance solutions. This approach will constitute a contribution for the future guidelines on pavement maintenance which will be a deliverable of the DVDC project. The project will also lead to the development of a more advanced model for the description of the fatigue behaviour of cracked or damaged materials.