"The presence of polycyclic aromatic hydrocarbons (PAH) in reclaimed asphalt (RA) is a problem for its recycling. Due to its carcinogenic compounds, which are released by vapors when heated, asphalt material with high PAH content is not recyclable in warm, or hot mix asphalt. For recycling purpose it is necessary to check the content of PAH in reclaimed asphalt. To determine this content time-consuming and costly investigations like thin layer chromatography or high-performance-liquid-chromatography are usually applied.
In order to identify an alternative method for PAH detection, 56 PAH-contaminated asphalt granulate samples with various PAH contents were measured via FTIR-ATR spectroscopy on recovered binders from the RA samples. Therefore, a cold recovery method was applied using toluene which allows to quickly recover the required small amount of binder. Additionally, the 16 PAH-EPA according to the list, which was compiled by the U.S. Environmental Protection Agency and classified as priority environmental pollutants, were measured by FTIR-ATR to compare them to the spectra of PAH-contaminated reclaimed asphalt.
To evaluate the IR-spectra, the peak areas, peak area ratios and peak height for different spectral areas in the range from 700 cm-1 to 1200 cm-1 were examined which made it possible to calculate index values, representing the proportion of PAH compounds.
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FTIR-ATR spectroscopy; PAH detection; reclaimed asphalt