Modeling of x-ray diffraction spectra of asphalt binders in condensed matter physics

Asphalt binders from 20 samples were obtained from Canada (Ontario and Alberta), the USA (Montana), and Venezuela. Thin-film samples, each measuring about (lmm), were heated at a temperature of 150 °C for 10 minutes on glass slides. The X-ray diffraction (XRD) patterns were obtained with monochromatic Cu K" radiation (40kV and 40mA) on a Rigaku DMax 2200V-PC. Profile-fitting performed utilizing Pseudo-Voigt and Pearson VII functions (Linear background, Exponent = 2.0 and Lorentzian =1.0) over the ranges 5° to 35° and 60° to 110° = 2#. To the best of our knowledge, this study represents the first time XRD spectra modeling that has employed Generalized Fermi Function (GFF) in asphalt binders. Using these functions, analysis of the broadening of diffraction Peaks on the asphalt thin-film was analytically simulated and measured. In these simulations, two key parameters were used (exponent=2.0 and Lorentzian = 1.0). The results of our study indicate a clear correlation amongst the Pseudo-Voigt and Pearson VII. However, a poor correlation was found with the GFF model. Additionally, the integral width (known as the full width at half maximum, or FWHM) of the diffraction Peaks were employed to approximate the experimental X-ray line profiles from the samples used. The two major factors which are closely related to aging tendencies under low temperatures are identified in the asphalt binder samples, using XRD of thin films. Based on these results, it is clear that asphalt pavement easily cracks in cold climates, while rutting is an ongoing issue in hot climates. Our results indicate that, in order to enhance the durability and overall performance of asphalt pavements, we need to have adequate understanding on a microscopic level, the composition and structure pertaining to the asphalt binders.