Fingerprint Components and Quantitative Analysis of Volatile Organic Compounds of Asphalt Materials

The environmental impact of asphalt materials is one of the key issues for promoting green transportation and reducing air pollution. Quantitative analysis of the volatile organic compounds (VOCs) released from asphalt materials is quite challenging because of their relatively unnoticeable or small release quantity and complex compounds. This study focuses on the chemical characteristic analysis of asphalt VOCs. First, coexisting, independent, and ultramicro components in asphalt VOCs from five different asphalt materials were analyzed in detail. VOC information obtained from 80 types of asphalt materials was collected to establish a database of fingerprint components of asphalt VOCs. Second, the relationship between the released quantity and peak area from chromatograms in a mass spectrometer study was established for every fingerprint component. Research results indicate that the release characteristics of VOCs differ for each asphalt material. The chemical components and release quantity are highly variety-dependent. Different asphalt materials provide different VOC information. Fingerprint components of asphalt VOCs exhibit the highest peak area and degree matching of chromatograms and a high toxicity. These VOCs include 2-methylpentane, n-hexane, 3-methylhexane, heptane, 2-methylheptane, acetone, methacrolein, butyraldehyde, isovaleraldehyde, benzene, toluene, and carbon disulfide. Considering the relationship between release amount and peak area, the characteristics of fingerprint components can be used for the quantitative analysis of each VOC component and the total VOC release quantity from asphalt materials. The two types of pen 70 and two types of pen 90, and styrene-butadiene-styrene modified asphalt binders exhibit a total VOC release of 3.00, 2.33, 2.01, 1.75, and 1.44 μg•g-1, respectively, when they are heated to 160℃. The chemical characteristics of asphalt VOCs indicate that n-hexane, 2-methylpentane, and heptane are the most released types of VOCs from the pen 70 asphalt binder, whereas butyraldehyde is the most released type of VOC from the pen 90 and SBS modified asphalt binders, where 0.76 μg•g-1 of butyraldehyde is released from the pen 90 asphalt binder