Abstract Concrete construction is responsible for around 8% of global greenhouse gas emissions. Reducing the carbon footprint of concrete is becoming crucial as its global production is expected to increase sharply in the coming years. One way to achieve this goal is to use the ability of concrete to fix CO2 by carbonation. Controlled by the diffusion of gaseous CO2 gas, carbonation is a reactive transfer which turn calcium oxides into calcium carbonates. At the end of their service-life, concrete structures are reduced by crushing into recycled concrete aggregates (RCA). Commonly used in road construction, recycled aggregates are also more and more reused in concrete mixtures as a substitute for natural aggregates. The CO2NCRETE project is focused on the sequestration of CO2 by accelerated carbonation of aggregates recycled with industrial gases. Recent literature reviews showed that this approach is the most promising among the strategies envisaged to reduce the carbon footprint of concrete construction. Most studies also show that carbonation improves the properties of RCA and thus their recyclability. The carbonation of crushed concrete aggregates is therefore a step towards a circular and carbon neutral economy, called the wishes of Europe. Among CO2 mineralization methods for capture, utilization and carbon sequestration (CCUS), carbonation of RCA can be envisaged as an attractive one, since the raw material, i.e. demolition concrete, is available in large quantity. The most obvious source of CO2 for this process is gas from cement kiln, since cement manufacturing is the main cause of the high CO2 emissions from concrete construction. However, there are other potential sources of gas with high concentrations of CO2. These includes petrochemical plants or more local sources such as household waste incinerators. Optimizing the carbonation process is the main scientific obstacle raised by the accelerated carbonation of RCA. If the atmospheric carbonation of concrete is an inevitable phenomenon, the degree of carbonation under natural conditions can remain quite low. Consequently, the ambition of the CO2NCRETE project is a fundamental understanding of the sequestration of CO2 by RCA for gases rich in CO2 at high temperatures and / or pressures. The expected result is the identification of the levers of acceleration and maximization of carbonation by means of the process conditions. These are in particular the CO2 concentration, the pressure and the temperature of the gas, the contact time between the gas and the material and the initial state of RCA. To that end, the CO2NCRETE project is organized into five tasks offering original approaches, from experiments on carbonation of RCA under severe conditions to advanced modelling with coupling of discrete models and reactive transfer models. A task is also devoted to assessing the effectiveness of the processes with respect to environmental and economic impacts. The project brings together laboratories recognized for their work in the fields of carbonation, recovery of deconstruction waste, multi-scale modelling and thermochemistry of complexes, namely: LaSIE, GeM, IFSTTAR, IRC and LGM. CERIB completes this team to make the link with the industrial sector of concrete.

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.