Tracking Aging of Bitumen and Its Saturate, Aromatic, Resin, and Asphaltene Fractions Using High-Field Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Abstract

Bitumen is a widely used material, but its aging behavior is only understood at a macroscopic level as hardening and embrittlement over time. To assess bitumen aging behavior in the long run, the pressure aging vessel (PAV) testing procedure was developed. However, this procedure including high-pressure and high-temperature oxidation of the bitumen has not yet been understood on a molecular level. Here, a bitumen sample and its SARA fractions, i.e., saturates, aromatics, resins, and asphaltenes, were investigated in comparison with their aged samples to study changes of their chemical compositions. Negative electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry [ESI(−)] FT-ICR-MS was used to analyze samples. The effect of aging was characterized using the aromaticity equivalent (X c), double bond equivalent (DBE), and van Krevelen plots. It was found that aging induces reduction of condensed aromatic compounds to alicyclic and open chain aliphatic compounds, while small aromatic compounds have been found to be relatively stable (or altered only slightly). Abundant alterations were detected in unaged bitumen. These changes can be assigned to resins and asphaltenes as compared to saturates and aromatics. Overall, alterations of highly condensed compounds were found to be related to aging. Furthermore, molecular series of CHO, CHNO, and CHOS fragments were more susceptible to oxygenation in bitumen, aromatics, resins, and asphaltenes as compared to saturates. In addition, molecular changes in asphaltenes showed a significant difference from classical assessment with high content of condensed aromatic compounds. Rather, the most abundant compounds in asphaltenes appear to be more saturated and apolar.

Rheological, spectroscopic and microscopic assessment of asphalt binder ageing

“…The saturate fraction does not alter significantly during the ageing process; however, the asphaltenes, aromatics and resins undergo a change caused by RTFOT and PAV ageing. While the concentration of aromatic compounds decrease with progressive ageing (Gueit & Robert, 2012;Handle et al, 2017), the amount of asphaltenes is increasing with RTFOT and PAV ageing, whereby PAV ageing causes a stronger increase in the asphaltene concentration. Therefore, an increase in the colloidal index (agglomeration of asphaltenes as a result of the decrease in the aromatic concentration) is expected.…”

“…However, modern spectroscopy shows that there is no sharp distinction between fractions and transition fractions containing intermediates (Hofko et al, 2019). These fractions may exhibit small amounts of neighbouring fractions due to inaccurate separation (Handle et al, 2017).…”

Sulfate Alters the Competition Among Microbiome Members of Sediments Chronically Exposed to Asphalt

“…Mass spectra of the N and H samples provided several thousand mass peaks, half of which could be assigned to molecular compositions CHO, CHNO, CHOS and CHNOS using conservative assignment criteria ( Hertkorn et al, 2016 ; Handle et al, 2017 ). The patterns of these molecular compositions differed between the two sediment types ( Supplementary Figure S8 ).…”

New Experimental Approaches to Analyse the Supramolecular Structure of Rejuvenated Aged Bitumens

“…But bituminous materials are easily subject to oxidative aging during pavement service life, especially in conditions of thermal and / or ultraviolet radiation [7,8]. It is well assessed that oxidized bitumen is characterized by reprocessing temperatures higher than fresh one, because most of the condensed aromatic components and resins, which are responsible for a certain grade of mobility, are converted into highly oxygenated polar and more saturated compounds (asphaltenes and saturates), [9]. Indeed, the depletion of polycyclic aromatic compounds with amphiphilic activity and acting as supramolecular cage surrounding the polar asphaltenes, may lead to an increase of average colloidal sizes dispersed in the continuous a polar maltene phase.…”