Engineering properties, microplastics and emissions assessment of recycled plastic modified asphalt mixtures.

The use of recycled plastic in asphalt is raising interest since contributing to increase the sustainability of roads pavements. The engineering performance of such roads are commonly assessed but scarcely correlated to the environmental impacts of incorporating recycled plastic in asphalt. This research encompasses an evaluation of the mechanical behaviour and environmental impact of introducing low melting point recycled plastics, low density polyethylene and commingled polyethylene/polypropylene, to conventional hot mix asphalt. While this investigation reveals a reduction in moisture resistance between 5 and 22 % contingent on the plastic content, the benefits include a significant 150 % enhancement in fatigue resistance and 85 % improvement in rutting resistance when compared with conventional hot mix asphalt (HMA). From an environmental perspective, high-temperature asphalt production with higher plastic content resulted in decreased gaseous emissions for both types of recycled plastics up to 21 %. Further comparison studies indicate that microplastic generation from recycled plastic-modified asphalt is comparable to that from commercial polymer-modified asphalt products, long employed by the industry. Overall, the use of low melting point recycled plastics as an asphalt modifier is promising since offering both engineering and environmental benefits when compared to conventional asphalt.

Analysis of possible carcinogenic compounds in recycled plastic modified asphalt.

The incorporation of recycled plastics in asphalt mixtures is getting a growing interest, however, exposing recycled plastics to the high working temperatures of asphalt has posed health and safety concerns. Few studies have paid attention to assessing health and environmental risks concerning recycled plastic-modified asphalt. This study investigates the release of 6 carcinogenic compounds from asphalt modified with recycled plastics, 4 volatile organic compounds (VOCs) and 2 polycyclic aromatic hydrocarbons (PAHs). The concentration of each compound was quantified by GC-MS. Human health risk assessments were conducted using probabilistic methods to assess the risk for an average Australian construction worker to get non-carcinogenic and carcinogenic health issues when exposed to conventional and plastic-modified asphalt fumes. Results showed that non-carcinogenic and carcinogenic risks related to VOC carcinogens (benzene, trichloroethylene, tetrachloroethylene and styrene) are negligible while PAHs (benzo[a]pyrene and dibenz[a,h]anthracene) constitute a possible non-carcinogenic risk and low carcinogenic risk for workers exposed to asphalt fumes. Overall the incorporation of recycled plastic in asphalt reduced the risk for workers to get non-carcinogenic and carcinogenic health issues compared to conventional asphalt mixes. ENVIRONMENTAL IMPLICATION: With increasing trends of using recycled plastics as road materials, concerns about the exposure of workers to carcinogenic gaseous emissions have been raised. This study demonstrates a non-carcinogenic and carcinogenic risk assessment on exposure to recycled plastic modified asphalt fumes. The findings suggest that recycled plastics decrease non-carcinogenic and carcinogenic risks compared to conventional asphalt.