Effects of different inhibitors on emission characteristics, environmental impact and health risk of volatile organic compounds from asphalt binder

Volatile organic compounds (VOCs) of asphalt will cause adverse environmental impact and workers' health risk, inhibitors can be used to reduce the emission of VOCs from asphalt. Three inhibitors, including activated carbon (AC), expanded graphite (EG) and hydrotalcite (MA), were used to modified asphalt in this work. The effects of inhibitors on the VOCs emission characteristics of asphalt were investigated at multiple levels of VOCs total concentration, groups distribution and components characteristics. 101 asphalt VOCs components were detected, among which alkane accounted for more than 50% of the total concentration, followed by aldehyde and benzene. AC with the largest specific surface area and pore capacity exhibited the best inhibitory effect on the emission of VOCs with total concentration inhibition rate of 45.58%, followed by MA, while excessive MA would have adverse effect. Over 90% of VOCs components emissions had been suppressed by AC and EG. And inhibitors had the best inhibitory effect on the emission of olefin and aldehyde in VOCs, followed by ketone, but had the worst inhibitory effect on alkane, which was due to the weak interactions between non-polar alkane and polar hydroxyl on the surface of inhibitors. Furthermore, the effects of different inhibitors on the environmental impact and health risk of VOCs from asphalt were also systematically studied. The highest total inhibition rate of OFP and SOAP from asphalt VOCs by AC was only 58.3% and 21.7%, which was ascribed to the limited suppression on OFP and SOAP generated by alkane and benzene. Meanwhile, the non-carcinogenic risk from asphalt VOCs was mainly caused by acrolein with a contribution rate of 80.0%, AC and EG can completely inhibit the emission of acrolein in asphalt VOCs, while MA showed the poor performance. The contribution rate of acetaldehyde to the carcinogenic risk of asphalt VOCs reached 93.7%, while inhibitors had limited inhibitory effects on its emissions. This study contributes to a deeper understanding of the correlation mechanism between inhibitors, emission reduction characteristics of asphalt VOCs and environmental-health benefits, which could provide theoretical support for the design of bituminous material with low environmental-health load.