Reclaimed asphalt concretes with high recycling rates: Changes in reclaimed binder properties according to rejuvenating agent

For environmental protection and to reduce costs, asphalt concrete manufacture incorporates reclaimed materials from the deconstruction of road surfaces under renovation in a process designed specifically to reduce the use of virgin materials (bitumen and aggregates). When the recycling rate is high (over 30% of reclaimed asphalt pavement -Rap-), it is essential to control the properties of the final binder -RacB- (mixture of reclaimed asphalt pavement binder -RapB- and virgin binder-VB-) to guarantee the mechanical performances of the reclaimed asphalt concrete. The aim of the present study was to consider the rheological characteristics of the virgin binder and the type of rejuvenating agent it contained and their effect on the conventional and rheological characteristics of the final binder; the reclaimed asphalt pavement binder used in all these tests was first defined in terms of its rheology and consistency. All the final binders were obtained using a methodology which ensured a common controlled consistency, whichever virgin binder was used. The effect of aging on these final binders in the course of manufacture and during the lifetime of the asphalt concrete on the road was simulated experimentally by the RTFOT (Rolling Thin Film Oven Test) and the PAV (Pressure Aging Vessel) procedure. A rheological study of all the binders was then carried out using traditional standard tests, and in addition a specifically adapted experimental procedure was used to assess the behaviour of the product at different operational temperatures.

► RAP Rejuvenation at high rate allows the production of binders with conventional consistency characteristics.
► Pure bitumen 35/50 is always more viscous than regenerated final binders.
► Vegetal oils RAP Rejuvenation leads to final binders that require aging before use.