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 (GCMS) 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.