Brittleness progression for short- and long-term aged asphalt binders with various levels of recycled binders

It is widely accepted that using reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS) can improve the sustainability of pavements by reducing cost and and environmental footprint. However, this should be only valid when short- and long-term pavement performances are not compromised. This paper presents an experimental evaluation of the rheological properties of binders from various sources to investigate the effects of ageing and increasing asphalt binder replacement (ABR) levels achieved by adding RAP and RAS. In this study, binders were recovered from five asphalt concrete (AC) designed with varying ABR percentages (ranging from 0 to 60%) and evaluated using various rheological parameters. In addition to the standard Superpave grading parameters, the additional rheological parameters for low-temperature cracking susceptibility, block and fatigue cracking were derived from various dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests. In order to investigate effects of long-term ageing, base binders were subjected to extended ageing times using standard ageing protocols. Based on the outcome of the experimental programme, it was concluded that AC with ABR levels above 20% (RAS only) could suffer from short- and long-term cracking problems. Asphalt concrete with high ABR content can be at an already critically aged condition right after production. In addition, it was observed that ageing progresses much faster in the binders of such mixes.