Ageing characteristics of RAP binder blends – what types of RAP binders are suitable for multiple recycling?

Two rolling thin-film oven-aged asphalts were blended with 15% and 50% of extracted reclaimed asphalt pavement (RAP) binders to investigate the effect of RAP content and properties on the long-term laboratory ageing characteristics of asphalt binders. The results from both chemical and rheological analyses indicate that the ageing characteristics of blended binders are dependent on fresh asphalt binders and that different virgin binders interact with different RAP binders differently and the performance grade (PG) adjustment is asphalt and RAP binder dependent. Some asphalts require higher PG adjustment than others. The mixing of virgin binders with RAP binders contributes to different stiffening effects based on the virgin asphalt–RAP interaction. The results show that the change in stiffness increase as a function of ageing times for RAP-blended binders is similar to that of a typical chemical ageing kinetic model, where the stiffness initially increases rapidly and then levels off at longer ageing times.