Low-temperature Fracture in Reactive-ethylene-terpolymer-modified Asphalt Binders

This paper reports on the low-temperature fracture and yield properties of a number of Strategic Highway Research Program asphalt binders that were modified with 5% by weight of a reactive terpolymer of ethylene, butyl acrylate and glycidyl methacrylate. Selected binders were also tested with the addition of small amounts of phosphoric acid. Fracture toughness and energy were determined at temperatures close to where the stiffness reached 300 MPa while the 2% offset yield stress was determined at somewhat lower strain rates in compression. Significant differences were found in the fracture properties ( K Ic and G Ic ) of these binders depending on the compatibility of the polymer with the base asphalt. It is suggested that the fracture energy and yield stress at low temperatures may be able to more accurately grade binders for their performance with respect to thermal stress cracking in the pavement compared to the currently used SHRP specification properties.