Evaluation of recycling agent dosage selection and incorporation methods for asphalt mixtures with high RAP and RAS contents

•Three recycling agent dosage selection methods were evaluated using binder blends.•The evaluation included ΔTc, PG, stiffness, and phase angle of the binder blend.•The method to restore high-temperature PG yielded the best results.•The stiffness and phase angle of the binder blend were restored even after aging.•Guidance on recycling agent incorporation based on mixture coatability was provided. Economic and environmental demands motivate transportation agencies to increase the amount of reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS) used in asphalt pavements. These pavements often require a recycling agent to reduce the likelihood of premature cracking. Estimating an optimum recycling agent dosage is critical to maximize its benefit. In this study, three recycling agent dosage selection methods based on the restoration of the performance grade (PG) of the recycled blend (virgin binder, recycled binder, and recycling agent) were explored. Based on the performance of the recycled blends, the method to restore high-temperature PG is recommended to determine the optimum recycling agent dosage.