Determination of SARA fractions in asphalts by mid-infrared spectroscopy and multivariate calibration

The SARA fractions in petroleum asphalts for road paving play a dominant role in the pavement performance of asphalt binders. In this study, a rapid and accurate determination method of SARA fractions in asphalts was proposed using Mid-Infrared (MIR) spectra and Partial Least Square Regression (PLSR) modeling method. Firstly, the blending and progressive aging process employed in this study successfully prepared 84 asphalt samples with fair differences in their Saturates, Aromatics, Resins and Asphaltenes (SARA) fractions. Secondly, the SARA fractions and MIR spectra of these samples were measured and collected by standard test methods, respectively. Finally, four quantitative calibration models were developed for each fraction using MIR spectra and PLSR method, and the validation results verified the high consistency between the measured values and the predicted values as well as the reproducibility and repeatability of the proposed method. This MIR-PLSR method was able to provide a faster SARA determination than the standard test methods through a single MIR spectrum. It could probably be used for the real-time quality control of asphalt production and the in-situ quality inspection of asphalt materials in road construction using portable equipment.

Automated summary

This study proposes a rapid and accurate method for determining SARA fractions in petroleum asphalts using MIR spectra and PLSR modeling. It successfully prepares asphalt samples with different SARA fractions through blending and progressive aging process. By measuring and collecting the SARA fractions and MIR spectra of these samples, quantitative calibration models are developed using the MIR spectra and PLSR method. The results show high consistency between the measured and predicted values, indicating the method's reproducibility and repeatability. This MIR-PLSR method can provide faster SARA determination than standard test methods, making it applicable for real-time quality control and in-situ inspection of asphalt materials in road construction.