Laboratory evaluation of PAH and VOC emission from plastic-modified asphalt

Recycled plastic modified asphalt is an emerging topic in the road construction industry that has been studied meticulously from a physical and mechanical perspective. However, the exposure of recycled plastics to high temperatures has been a growing concern due to the possible release of toxic gases associated with burning plastics. This research investigates laboratory-generated fumes from recycled plastic modified asphalt incorporated via two different methods using four types of recycled plastic from post-industrial and post-consumer streams. Results were compared against conventional asphalt prepared using neat bitumen or commercial polymer-modified bitumen. A direct liquid injection method using gas chromatography-mass spectrometry (GC-MS) was employed to quantify 48 volatile organic compounds (VOCs) and 16 polycyclic aromatic hydrocarbons (PAHs). Results revealed that the incorporation of recycled plastics could effectively reduce (up to 34% VOCs and 51% PAHs) overall emissions at all working temperatures except when recycled acrylonitrile butadiene styrene was mixed at 180 °C. Further tests involving sorption analysis of plastics revealed that plastics have an adsorbent capability with a selectivity towards PAHs (compared to VOCs) and therefore further justifying that the addition of recycled plastics in asphalt can effectively limit the total emitted compounds.