10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Emission of Particulate Matter, VOCs and PAHs from Different Asphalt Mixes
MENG XIU, Xianyu Wang, Jochen Mueller, Andrew Beecroft, Lidia Morawska, Phong Thai, Queensland University of Technology
Abstract Number: 1118 Working Group: Aerosol Exposure
Abstract Asphalt is widely used for road pavements across Australia, and is considered heavily resource intensive. On the other hand, in Australia, millions of tyres reach the end of their service life every year and need to be disposed of. New technology allows end-of-life tyres to be processed as crumb rubber and recycled in road construction as an additive to save materials and reduce waste, with the product known as crumb rubber modified (CRM) binder. However, application of asphalt mixes, including the CRM binder, can generate toxic fumes and emissions including those of total suspended particles (TSP), volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs). These pollutants not only deteriorate air quality in the immediate vicinity, but also raise health risks to paving workers. Research outcomes regarding environmental and health issues associated with the application of CRM mix are still scarce.
This study, therefore, aims to compare the levels of air pollutants during pavement of different asphalt mixes including the CRM mix, as well as assess the risk for their emissions. Two field investigations were performed on several different construction site. Emission factors of TSP, VOCs and PAHs from different asphalt mixes were measured using portable flux chambers, connected simultaneously with a vacuum canister (for VOCs sampling) and two active air samplers (for TSP and PAHs sampling respectively). A total of 60 VOC analytes and 13 PAH compounds are analysed by a gas chromatography-mass spectrometer (GC-MS) and a gas chromatograph coupled to a high-resolution mass spectrometer (GC-HRMS), respectively. For personal exposure, a Dustmate device is provided to the workers (a paver driver and a screed operator) to monitor personal exposure to particulate matter (PM), including PM2.5, PM10 and TSP, which may be inhaled via the respiratory pathway.
In the results of the field study 1, TSP levels were found to be 2.5 times higher for the CRM operation than PMB, and higher than the Queensland air quality objective. Apart from the appearance of some alkanes and naphthalene during the construction work, the levels of other VOCs are mostly below limit of report. Although there was an increase in the level of BaP and PAHs in the ambient air during and shortly after the construction, the highest concentrations measured (0 – 3 hrs after spray) in both treatments were much lower than the Queensland air quality objective. The results of the field study 2 showed that CRM hot mix was likely to produce higher concentration of air pollutants (VOCs and PAHs) than both CRM warm mix and polymer mix, even though no significant difference (p>0.05) was observed for levels of TSP, PM10 and PM2.5 at work site. The data from this study is expected to contribute to the overall assessment of the comparative risk of using ground tyre rubber techniques in road paving industries in Queensland.