Rheology-based optimization of the recovery procedure for long-term aged bitumens using a rotary evaporator

The use of RAP presents challenges due to its inherent variability, making reliable binder characterization essential before incorporating it into new asphalt mixtures. This study investigated the recovery and rheological characterization of highly aged asphalt binders, focusing on the standardization of a recovery procedure suitable for RAP-derived binders. To achieve this objective, rheological tests using a Dynamic Shear Rheometer (DSR) were performed on binders aged 40 h in the Pressure Aging Vessel (PAV) and subsequently recovered in a rotary evaporator, aiming to parameterize the recovery process. For this purpose, frequency and temperature sweep tests, determination of the Glover–Rowe Parameter (GRP), German BTSV (Binder-Fast-Characterization-Test) classification, Performance Grade (PG) evaluation, and permanent deformation (MSCR) and fatigue (LAS) tests were conducted to assess the effects of the residual solvent and additional oxidative aging. The rheological results showed that conventional binders were more sensitive to residual solvent and to oxidation induced during recovery. The proposed rotary-evaporator protocol indicated that intermediate recovery times (85–130 minutes) produced binders more representative of their actual aged state, without significant changes in rheological properties. Among the rheological parameters, GRP and BTSV were the most sensitive to residual solvent. GRP revealed a higher cracking tendency in RAP-derived binders, while BTSV captured both solvent effects and the aging history of the materials. MSCR results showed that conventional binders were more affected by prolonged recovery, whereas modified binders preserved their properties. The procedures investigated contribute to advancing RAP binder characterization by providing relevant parameters for recycled mixture design and for establishing appropriate recovery practices for highly aged binders.