ارزیابی تحلیلی الگوهای بوی آسفالت در تولید آسفالت مخلوط گرم Analytical assessment of asphalt odor patterns in hot mix asphalt production

1. Introduction The focus on the atmospheric emissions, particularly the odorous ones, related to industrial production sites and specifically to hot mix asphalt (HMA) manufacturing facilities, was emphasized in the last years, in accordance to the increasing sensitivity towards environment and human health, but also to the growing proximity of emission sources to urban and already settled areas (Belgiorno et al., 2013; Invernizzi et al., 2017). The production of asphalt paving mixtures, consisting of a hot blend of aggregates and asphalt cement, for road pavement construction and maintenance, take place in stationary or mobile plants. Nowadays, there are about 4500 HMA plants both in Europe and in the USA, half of which are also fit for hot and warm recycling (EAPA, 2017; Paranhos and Petter, 2013). Virgin or milled reclaimed asphalt pavement (RAP) aggregates are blended and mixed at about 170e190
C with hot stored liquid asphalt binder to produce an asphalt paving mixture (Stimilli et al., 2016). The resulting HMA is delivered in properly covered trucks to the paving site, where it is placed and then compacted in a temperature range of 140e160
C. During storage and handling of asphalt at these elevated temperatures, a complex mixture of predominantly hydrocarbons having a broad boiling point range is released into the atmosphere (Autelitano et al., 2017a; The Asphalt Institute and Eurobitume, 2015). These temperature dependent emissions are a dynamic equilibrium of gases, vapors and mists/aerosols consisting of water, products of combustion (CO2, NOx and SOx), carbon monoxide (CO) and organic compounds of various species, including volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs), some of which may have short- and long-term adverse health effects (EPA, 2000; Ventura et al., 2015). As far as HMA plants is concerned, several standards and directives, all aimed at containing ducted emissions, were drawn up for limiting the emissions of certain specific substances, generally referable to dusts or particulate matters (PM10, PM2.5) and Greenhouse gases (CO2, NOx, SO2), without setting any specific limit on odorous emissions (AlmeidaCosta and Benta, 2016; Boczkaj et al., 2014; Jullien et al., 2010; Rubio et al., 2013). Also the scientific literature has generally analyzed asphalt emissions in terms of airborne substances reduction and toxicology risk, related above all to the occupational exposure, ignoring their odorous characteristics (IARC, 2013; Kriech and Osborn, 2014). But, odor is increasingly considered an atmospheric pollutant that can have a significant negative impact on both quality of life and economic activity. The odorous flows of HMA emitted in plants or during the paving operations and hot-inplace recycling processes in the worksites can severely limit the usability of the territory, representing a cause of unquestionable and persistent annoyance for the population living in their vicinity and for workers.