Characterization of the Influence Factors of Low-Temperature Fracture Properties for Serving Asphalt Pavements Using Layer Core Samples

Abstract

A comprehensive study was conducted to investigate the influence of various factors on the fracture properties of asphalt mixtures obtained from three different asphalt layers for serving asphalt pavements. The fracture properties of 195 semicircular specimens covering three asphalt layers of 13 road sections—which represent a combination of influence factors including aggregate gradation, service age, equivalent single axle load (ESALs), specimen location, and air voids—were evaluated by performing semicircular bending (SCB) fracture tests. Two parameters, fracture energy and tensile strength, were calculated from the experimental data. A statistical analysis reveals that the fracture properties of in-service bottom asphalt mixtures are only dependent on air voids, ESALs only acts on the tensile strength of the surface and the middle asphalt layers, and the fracture energy of the upper two asphalt layers is strongly related to aggregate gradation. A detailed analysis on the influence factors revealed that service age affects both the tensile strength and fracture energy of the upper two asphalt layers, whereas ESALs impact the tensile strength of the surface asphalt layer more than the service age and the opposite is true for the middle asphalt layer. A comparison of tensile strength and fracture energy shows that there are some differences between the two. Therefore, it is more effective to combine them to evaluate the fracture properties of asphalt mixtures.