Contributions of fourier-transform infrared spectroscopy technologies to the research of asphalt materials: A comprehensive review

Fourier-transform infrared spectroscopy (FTIR) has become a crucial method for both qualitative and quantitative analysis in characterizing asphalt materials. The present work aims to provide a comprehensive review of recent uses of FTIR in this field, that ranged from material quality control, material identification, to the analysis of modification mechanism, including ageing mechanisms, as well as for macroscopic performance prediction. The narrative unfolds within a broader context, with the basic principles, and insightful comparisons with ultraviolet-visible (UV-vis) spectroscopy, Raman spectroscopy, and fluorescence spectroscopy. The instrumentations employed in FTIR research are inspected in detail, delving into testing modes, sample preparation, and data analysis methods, with a particular emphasis on its ability to identify asphalt components at the molecular level. Furthermore, FTIR analysis provides useful indications for various applications: i) quality identification; ii) asphalt materials modifications and ageing states identification according to molecular changes; iii) prediction for the physical and rheological properties of asphalt binder based on chemometric method. The prospects in asphalt research are proposed stressing the relevance of combining FTIR analysis to high-throughput experimental methods and other spectroscopy technologies, and coupling to machine learning (ML) methods. This paper provides a reference for researchers who intend to explore the quality control and to analyze asphalt binders from a microscale perspective, fostering further research on relationships between microscopic compositions and macroscopic properties.