Future recyclability of hot mix asphalt containing recycled plastics

The recyclability of reclaimed asphalt pavement (RAP) from conventional asphalt concrete has been well reported in the literature. However, the future recyclability of plastic-modified asphalt at the end of its service life (P-RAP) is still questionable. The lack of studies on the recyclability of P-RAP is mainly due to the current unavailability of the aged material from the field, reflecting that the application of recycled plastics in asphalt is still mainly in the research phase but not widely applied in practice. There is a concern about the ability to recycle P-RAP in the future, as if the material is not recyclable or the addition of P-RAP would significantly reduce the new mix quality compared to conventional RAP. Thus, it is crucial to evaluate the future recyclability of P-RAP prior to the application of plastic in asphalt mixes. This study was carried out to assess the ability to recycle P-RAP produced by three different mixing methods: dry, wet, and mixed methods. First, loose plastic-modified asphalt mixes were produced and aged under certain laboratory conditions before going through a crushing process that ultimately produced P-RAP. Then, P-RAP was incorporated into a new hot mix at a percentage of 30%. A comprehensive mechanical testing scheme was performed to assess the compactability, moisture resistance, cracking tolerance, fatigue resistance, and rutting performance. The study found that recycled plastic-modified asphalt mixes are totally recyclable and provide similar performance to standard RAP mixes. This finding provides confidence for practitioners that recycled plastic-modified asphalt mixes can be reused as conventional RAP after their service life rather than being landfilled or treated as waste.