DIRECT MEASUREMENTS OF VOLATILE AND SEMIVOLATILE ORGANIC COMPOUNDS FROM HOT AND WARM MIX ASPHALT

摘要

Emissions from the production and paving of hot-mix asphalt are being increasingly scrutinized.The introduction of a range of warm-mix asphalt (WMA) technologies could potentially lead to areduction in these emissions. However, the measurement of these emissions is both complex andexpensive. To overcome this, the University of California Pavement Research Center (UCPRC)has developed a simplified protocol that can be used in addition to conventional methods, andwhich allows direct comparison of emissions from different mixes measured at the pavementsurface during construction. A portable "flux" chamber is used to capture and directly measureemissions before and immediately after compaction and then two hours after compaction.Emissions are collected in activated charcoal sorbent tubes and analyzed using gaschromatography mass spectrometry (GC-MS) in the laboratory to identify individual compounds.The protocol was evaluated during the construction of a test track, which will be used in anaccelerated pavement test to compare the performance of three rubberized hot-mix asphalt(R-HMA) controls against seven different rubberized warm-mix asphalt (R-WMA) sections. Themeasured reactive organic gases (ROGs) included selected volatile organic compounds (VOCs)and semi-volatile organic compounds (SVOCs). The results demonstrated that the warm mixasphalt technology type, temperature and level of compaction greatly influence the emissioncharacteristics. Based on the success of the pilot study, the project is being extended to measureother types of emissions, including polycyclic aromatic hydrocarbons, and to assess real timeanalysis methods.