(192j) Computational and Fourier-Transform Infrared Spectroscopy Study of Chemical Composition and Its Effect on Asphalt Aging

With over 90% of paved roads in the U.S. being asphalt pavements, their critical role in essential infrastructure is unquestionable. Increased recycling of asphalt concrete from these pavements is an integral component and one of the greatest opportunities for sustainable infrastructure. Being a core part of the pavement, asphalt is a very complex material. Its composition includes millions of different molecules which vary greatly from one asphalt to the next depending on the source of the petroleum and its processing at the refinery. It has been estimated that asphalt has 10⁵-10⁶ different molecules¹. The explicit representation of exact chemical species present in any asphalt binder is not feasible. One approach has been to capture asphalt chemistry by defining broad categories of molecules. Such an approach relies on generic SARA fractions where the composition includes saturated aliphatic compounds(S), naphthenic aromatics(A), polar aromatics or resins(R), and large polycyclic structures called asphaltenes(A) with heteroatoms. These groups with their different polarities have been related to the colloidal nature of the asphalt. Asphalt characterization and design are depending mainly on mechanical and rheological testing, to the near exclusion of chemistry. In this presentation, we discuss the model development of aged asphalt, the computational and the Fourier-transform infrared (FTIR) spectroscopy study of the asphalt aging and its effect, with a special focus on asphaltene molecules and their O-, N- and S-containing functional groups.