Assessment of aging state of bitumen based on peak-area evaluation in infrared spectroscopy: Influence of data processing and modeling

The presented study aims at an improved analysis of aging of bitumen based on the carboxyl peak. In general, infrared (IR) spectra are post-processed, including baseline correction and normalization. Moreover, the carboxyl-peak area determination method varies, strongly impacting the results. In this paper, different postprocessing steps and peak-area evaluations are systematically studied, providing insights into the robustness and repeatability of these methods. The peak-area serves as input for a proposed kinetic model of aging at a preferably small number of independent parameters. Based on this approach, a model is developed, which determines the bitumen aging state in respect to its overall aging potential.