Comparing the Slope of Load/Displacement Fracture Curves of Asphalt Concrete

Abstract

In order to quantify cracking characteristics of asphalt concrete, the use of fracture testing is becoming more common. When running fracture tests, often the load and displacement are recorded, and from these two values, the fracture energy can be calculated. Unfortunately, fracture energy is only a single value, so it is difficult to differentiate between two different mixtures that have the same fracture energy, but very different Load/Displacement curves. This research examined four sets of mixtures with similar fracture energies, but different material characteristics, including air voids, asphalt cement content, asphalt cement type, and polymer modification. After analyzing these four sets of mixtures, it was found that adding extra asphalt cement or polymer modification to a mixture increased the complaint behavior of the fracture curves for these specific mixtures. In addition, increasing the air voids decreased the compliance, while increasing the high temperature binder grade slightly increased the compliance. This indicated that important information of cracking characteristics of asphalt concrete can be overlooked when only using the fracture energy.