Characterization of long-term aged bitumen with FTIR spectroscopy and multivariate analysis methods

One of the most common techniques used to investigate bitumen aging from a chemical perspective is Fourier-Transformation Infrared (FTIR) spectroscopy. However, the majority of standard spectral interpretation simply covers the observation of single bands associated with carbonyls, sulfoxides or aromatic structures. A possibility for a more comprehensive post-processing of FTIR data is to apply multivariate analysis (MVA) methods. Although, MVA methods have already been used for classifying differently aged bitumen in the past, the deployed methods only included standard laboratory aging and failed to consider factors like reactive oxygen species or light. The purpose of this study was the investigation of aged bitumen samples with FTIR spectroscopy and subsequent data processing with MVA. Therefore, nine bituminous binders were subjected to aging with the Pressure Aging Vessel (PAV), Viennese Binder Aging (VBA) and light, followed by a characterization with FTIR spectroscopy and various MVA methods. It was possible to investigate the general structure of the acquired data and differentiate between the aging methods solely based on FTIR spectra. Furthermore, important wavenumbers for the classification were identified, including spectral features around the wavenumbers 3371, 3027, 2943, 1550 and 1324 and 848 cm−1 for the original spectra. This study shows the potential of MVA to maximize the information content gained by experimental analysis and for the development of fast and easy characterization methods.