Analysis of Virgin Asphalt Brands via the Integrated Application of FTIR and Gel Permeation Chromatography

Counterfeit asphalts have often been deliberately adulterated to reduce costs, which has seriously impeded the development of road and highway construction. In this study, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and gel permeation chromatography (GPC) were applied in combination to explore a fast, accurate, low-cost and efficient method to better identify the brand and quality of asphalt. Results revealed that ATR-FTIR spectra of seven brands of asphalt were basically identical, while they differ in benzene ring substituent content and (–CH₂–)n (n ≥ 4) content. The fingerprint intervals of virgin asphalt were 1770–1636 cm⁻¹, 1060–985 cm⁻¹ and 920–690 cm⁻¹. The aging degree of the same brand of asphalt was identified by 1770–1636 cm⁻¹ and 1060–985 cm⁻¹, while 920–690 cm⁻¹ range was used to identify the fingerprint interval of the original asphalt brand. GPC analysis revealed that the large molecular size (LMS) content of original Fu Lian and Shuang Long asphalt brands greatly differed which were not identified by FTIR. Owing to the thermal oxidation, the LMS content of the same brand of virgin asphalt increased by 4–6% after short-term aging. The present study based on the integrated operation of GPC–FTIR for the fast and accurate recognition and distinguishing between different brands of asphalts could be of potential practical applications.