Dear participants, hello. It's a pleasure to meet you again for this new technical session. I'm Yves Brosseaud from IFSTTAR. This video presents the stakes of the research and innovations in the field of recycling of hot asphalt mixes. The old asphalt mix or RAP come from the deconstruction of milling of old pavement courses made of asphalt materials. They constitute a resource of aggregate and asphalt which is: substantial, about seven million tons per year in France, 45 million in Europe, and close to 80 million in USA, or about 15 to 20% of the total annual production of asphalt mixes. Of good quality, selected from specifications adapted to road requirement, available to be recycled in new asphalt mixes, as long as it is verified, that they do not contain tar, (limit value in HAP of 50 milligram kilogram or asbestos. The use of RAPs is governed by characterization standards and regulatory texts, and by the carrying out of a prior study to determine the rate of recycled materials compatible with the end performances of the asphalt mix. These performances must be the same as those of "new" asphalt mixes, because they are used for the same purposes. Only recycling in asphalt mix plants allows for reuse of 60% of RAPs in hot or warn asphalt mixes. This rate has been rising every year, approaching 100% in the USA and in Germany in particular. This proven technique, in use for more than 30 years, involves all asphalt mixes for both base and surface layers of variable thickness, for pure asphalts and also asphalts modified with polymers, with recycling rates ranging from 10 to 60%. The recycling rates are a function of: the regulatory constraints of the markets and the available volumes, The RAPs themselves, according to the heterogeneity with diverse and varied sources, requiring operations for sorting, crushing-screening and mixing. Or the homogeneity of the RAPs, depending on whether it involves one single course (base or wearing), or one single asphalt mix composition, (grading an asphalt content), The residual characteristics of the aged asphalt, in terms of "binding properties", to define the nature and the dosing of the new asphalt, and its compatibility to regenerate this aged asphalt. Their storage, with low moisture content, (less than 3%) The asphalt mix plants, and their facilities: 10% for all of the plants that have a specific hopper for dosing of RAPs by weight, very variable rates of incorporation according to the technologies used, For example: up to 30% for drum mixers with parallel flows, up to 50% for drum mixers with counter-flow, up to 70% for separated double drums, one for the RAPs, one for the new aggregate, or the new asphalt mix plants with concentric drums (double barrel in the USA, with asphalt foam). The type of asphalt mixes made, the rates are higher for base courses than for wearing courses, all the more so because they are not so thick and the traffic is heavy and rapid. The current research involves: multiple recycling, how many times can an asphalt mix be recycled?: Does the old oxidized and hardened asphalt remain "mobilizable" in the form of a binder, (adhesion, elasticity, cohesion)? It is an inert material or not? For the wearing courses does the agreggate retain the friction/adhesion properties? Are they sufficient? Warm recycling, does it allow for the intimate mixing of the aged binder and the additional binder? The role and the action of regeneration agents. The value of recycling has been proven and explained within the framework of sustainable development. It allows for : efficient environmental results by: decreasing consumption and thus the extraction of non-renewable mineral and fossil resources. The reuse of asphalt mixes, if possible in the same pavement course, so there is no waste/dumping. A decrease in emission, A positive energy balance by Decreasing transport of the materials to be recycled, of raw materials and especially of asphalt, where the refinery is generally very far from the work site (transport by truck, train, or pipeline). Better yields of the asphalt plant if we can benefit from the presence of residual water in the RAPs, in the form of steam, to manufacture warm recycled asphalt mixes A decrease in the asphalt storage volume (less heating), a positive technical result. The recycled asphalt mixes are not second-hand asphalt mixes. The performances are equivalent, or even better. We can, for example, take advantage of the hardening of the aged asphalt to increase the rigidity of the asphalt mixes, And to produce high modulus asphalt mixes with higher performances than traditional pure asphalt and without using hard asphalts, a favorable economic outcome. In general, the condition for reuse and RAP studies are offset by savings of materiels and energy. Recycling asphalt mixes is imperative. The means and knowledge exists and the results have been extremely positive. We note that cold recycling on site with asphalt emulsion or asphalt foam is also a means to reprocess asphalt materials on site in the pavement, But the performances are poorer than for hot materials. However, hot recycling on site was abandoned for safety and environmental reasons. Thank you for your attention. This was our last session together. Enjoy the rest of the MOOC.