Feasibility of Using XRF for Assessment of Surface Free Energy Components of Asphalt Binder

Abstract

Recently the surface free energy (SFE) techniques are being used to mechanistically quantify bonding characteristics of aggregate-asphalt binder systems and consequently moisture-induced damage potential of asphalt mixes. Also, the chemical composition of the asphalt binder is known to be an important factor in determining the strength of the asphalt-aggregate bond. The present study was undertaken to explore correlations between the chemical compositions of the binders containing different additives with their SFE components. For this purpose, a PG 64-22 asphalt binder was collected from a local supplier in Oklahoma. A commonly used chemical warm-mix asphalt (WMA) additive and an anti-stripping agent (ASA) were also collected and blended with the PG 64-22 binder at two different proportions, namely 0 and 0.5% by the weight of the asphalt binder. The SFE components of the short-term aged asphalt binders blended with additives were determined using Dynamic Wilhelmy Plate (DWP) test. The elemental analysis of the binders was carried out using an X-ray Fluorescence (XRF) analyzer. From the DWP tests it was concluded that the additions of WMA additive and ASA had significant effects on the values of the SFE components of the neat binder. The XRF results are expected to help explain the changes in SFE components due to any additive in an asphalt binder. Also, this study is expected to help predict the surface free energies of the binder from its chemical composition using a less time-consuming XRF test.