Correlating the Asphalt-Binder BBR Test Data to the HMA (ML-OT) Fracture Properties

Abstract

An asphalt-binder is one of the key constituent elements that significantly influences and controls the fracture behavior and cracking performance of hot-mix asphalt (HMA). In particular, the low-temperature rheological properties of asphalt-binders are critical in terms of improving the HMA fracture properties in the laboratory and ultimately mitigating cracking in the field. The bending beam rheometer (BBR) is one of the most widely used laboratory test methods for evaluating and quantifying the asphalt-binder behavior at low temperatures, mostly using the stiffness (S) and m-value parameters. Using the Texas flexible pavements and overlays database, namely, the Texas data storage system (DSS), as the primary data source, this study was conducted to correlate the asphalt-binder low-temperature rheological properties (measured using the BBR) to the HMA fracture properties. The HMA fracture properties were measured in the laboratory using the monotonic-loading overlay tester (ML-OT). In general, the asphalt-binder low-temperature rheological properties [particularly the stiffness (S)] exhibited promising potential to predict the HMA fracture properties, namely, the tensile strain (εt) and fracture energy index (FE Index), with a coefficient of determination (R2) greater than 60%.