A rheological study on rejuvenated binder containing very high content of aged bitumen

Hot recycling of reclaimed asphalt pavement (RAP) coming from flexible pavement rehabilitation is a technique able to ensure real economic and environmental benefits related to the reduction of virgin bitumen and aggregate supply and to the reuse of a recycled aggregate. Otherwise, adequate performance of recycled materials with high amount of RAP must be guaranteed since the recycling involves the presence of old and stiffened aged binders within the mixture. In this perspective, the present experimental study was aimed at verifying in the laboratory the performance at mid and high-service temperatures of bituminous blends composed by 40% of virgin binder and 60% of old rejuvenated bitumen (simulating aged bitumen coming from RAP). Rheological properties of materials were studied through the dynamic shear rheometer, testing unaged, short-term aged and long-term aged samples. Viscosity, stiffness and permanent deformation resistance of recycled blends seemed to guarantee comparable behavior with those of original bitumens, regardless the aging condition of the materials. These findings seemed to demonstrate the effectiveness of the hot recycling procedure using rejuvenators to obtain suitable bituminous binder containing high amount of aged bitumen.