Study of thermal and photochemical aging of saturates, naphtenic-aromatics, resins, and asphaltene fractions of asphalt cement by FTIR and FT-ICR MS

While the resins and asphaltenes fractions were more sensitive to photochemical aging. [Display omitted] •This study evaluated, at the molecular level, the aging reactions in asphalt cement (AC).•AC fractions (saturated, naphthenic-aromatic, resins and asphaltenes) were degraded at 140 °C for 15 days.•Whereas AC samples were aged by rolling-thin film oven tests and Suntest;•All ACs samples and their fractions were analyzed by FTIR and FT-ICR MS.•The presence of oxygenated classes, with up to 8 oxygens, was observed;•It was also possible to observe that the saturated and aromatic fractions were more sensitive to thermal aging; The study at the molecular level of aging reactions that occur in asphalt binders contributes to the development of technologies to improve the quality and durability of these materials. However, due to the complexity of the chemical composition of asphalt, sometimes, it is necessary to promote fractionations to assess, with better resolution, where exactly these reactions are occurring. This study proposes to evaluate at the molecular level the aging reactions that occur in two different samples of asphalt cement (AC). Two virgin samples were aged by rolling-thin film oven test (RTFOT) and Suntest (ST) and fractionated into saturated, naphthenic-aromatic, resins and asphaltenes. After fractionation, the fractionated virgin samples were aged at 140 °C for 15 days. The fractions, as well as their respective ACs, were analyzed by Fourier transform infrared spectroscopy and Fourier-transformion cyclotron resonance mass spectrometry. As a result, the presence of oxygenated classes was observed in the saturated fraction, indicating that oxidations in aldehydes, ketones, and carboxylic acids occurred. The formation of clusters with up to 8 oxygens was also observed, leading to the hypothesis that the molecules were degraded, and then oxidized, resulting in the formation of polymerized species. In the naphthenic-aromatic fraction, the presence of oxygenated species was also observed and in the polar fractions (resins and asphaltenes), growth was observed in the NO class, indicating the presence of oxidation. It was also possible to observe that the saturated and aromatic fractions were more sensitive to thermal aging, while the resins and asphaltenes fractions were more sensitive to photochemical aging.