Understanding Bitumen Aging through Interrelationships and Aging Ratios

Abstract

Aging of bitumen can lead to fatigue and non-load-associated cracking of asphalt pavements. Performance grade specifications include threshold limits for rheological properties from specific ranges of binder behavior after laboratory aging. Some specifications include aging ratios (ARs) to limit the rate at which properties deteriorate. This study compares the evolution of interrelationships and ARs of performance parameters in specific areas in Black Space to understand the relative susceptibility of the binder behavioral spectra to aging. Unmodified and polymer modified binders are aged with the rolling thin film oven and pressure aging vessel, and tested with the dynamic shear and bending beam rheometers. It is seen in the study that there are both related and unrelated aging trends in the distinct stiffness-related ranges. Correlations in parameter development significantly improve when binders are grouped by similar features such as modification type or origin. Binder source and modification type and degree greatly dictate aging trends in the high-stiffness range. In the low-stiffness range, the initial hardness of the binder is indicative of aging potential. The evolution of properties may be influenced by either modification or binder source in the intermediate domain. When considering ARs for specifications, combining complementary ARs may provide reciprocal insights into binder aging.