Characterization of Fracture Properties of Asphalt Mixtures as Measured by Semicircular Bend Test and Indirect Tension Test

Abstract

The objective of this study was to investigate the intermediate temperature fracture resistance of various asphalt mixtures, as measured by the semicircular bending (SCB) and indirect tension (IDT) test methods, and to correlate these fracture properties to the cracking performance of Louisiana asphalt pavements. Effects of design and process-based factors such as mixture-producing technologies (e.g., hot mix versus warm mix), asphalt binder grades, aging of test specimens, and reclaimed asphalt pavement (RAP) content on the fracture properties were investigated. Results indicated that the SCB-measured critical strain energy release rate (J_c) values showed good correlation with the IDT-measured toughness index values, especially when laboratory-produced mixtures were compared. In addition, the asphalt binder grade and aging condition of specimens influenced the fracture properties of asphalt mixtures. Asphalt mixtures with polymer-modified asphalt binders exhibited greater fracture resistance than did those with unmodified asphalt binders. The aging of specimens decreased the fracture energy of asphalt mixtures while increasing their strengths. Warm-mix asphalt (WMA) technologies used to produce asphalt mixtures at reduced mixing and compaction temperatures did not negatively affect the fracture resistance of the produced mixtures. Further, incorporating high RAP contents of up to 30% in the WMA production did not seem to reduce the fracture resistance of the produced mixtures. The SCB-measured J_c values demonstrated a good correlation with field cracking performance data. These results demonstrate the suitability of the SCB test method for predicting the cracking performance of asphalt pavements at intermediate service temperatures.