Physico-chemical analysis of 12 unmodified 70/100 binders from different sources

Abstract

The diversity of bitumen has provided significant challenges in the bitumen research and its related industry. Due to the vast molecular diversity and complexity, not every bitumen from the same European specification classification behaves the same during its service life. To tackle this issue, this study presents a comprehensive physico-chemical characterization of 12 unmodified 70/100 bituminous binders originating from different crude oil sources and production routes. The binders were subjected to two different long-term ageing procedures — the standardized Pressure Ageing Vessel (PAV) test and an alternative ageing method, called Viennese Binder Ageing (VBA), which induces thermochemical ageing via the addition of reactive oxygen species, to evaluate the sensitivity of each binder towards different ageing factors. Beside conventional testing using softening point ring and ball and needle penetration, an absolute and relative chemo-mechanical correlation coupling Fourier Transform Infrared (FTIR) spectroscopy and the Dynamic Shear Rheometer (DSR) as utilized. The results reveal that the thermochemical approach from VBA induces significantly higher and more diverse LTA compared to the thermal ageing from the PAV. Binders subjected to non-standardized aging protocols such as the VBA, which intend to provide conditions closer to those found in the field, offer new insights into the diversity of binder aging within the same specification class. Furthermore, the proposed relative chemo-mechanical correlation provides a useful comparative framework for interpreting these differences and supports the selection of materials for enhanced pavement longevity.