Introducing New Indicators to Evaluate Fracture Properties of Asphalt Mixtures Using Semicircular Bending Test

摘要

The fracture properties of an asphalt mixture specimen can be different due to variation in raw material characteristic, mixture design, method of the mixture production, and environmental conditions. This paper summarized the fracture properties of the semicircular specimens analyzed using different methods. Loose asphalt mixtures from two asphalt mixing plants were collected and used for the sample preparation. Each mixture was unique with respect to variation in terms of binder type, binder content, aggregate gradation, filler type, and the types of asphalt mixing plants (drum or batch plant) which were used for the production of particular mixtures. The samples were tested using semicircular bending test, and compared in terms of maximum force, deformation at maximum force, stiffness, strain at maximum force, maximum stress at failure, fracture toughness, and fracture energy. The results indicated that samples produced using stiffer binders exhibited a higher resistance to fracture while consuming less energy to reach failure compared to those prepared using softer binder. In addition, this study proposed three indicators, including the velocity of fracture initiation (upsilon(FI)), velocity of crack growth (upsilon(CG)), and fragility index (FI) to gain a better understanding of the fracture behavior of asphalt mixtures with respect to the mixtures' crack resistance and its propagation. The results of upsilon(FI) and upsilon(CG) were highly dependent on mixtures brittleness, while FI exhibited an acceptable capability to differentiate mixtures crack potential regardless of their inherent characteristics.