Role of Modified Binders in Rheology and Damage Resistance Behavior of Asphalt Mixtures

Abstract

Rheological and damage characterization of asphalt mixtures under dynamic loading and different frequencies and temperatures can simulate a wide range of traffic loads and climate conditions. Unfortunately, the characterization of asphalt mixtures by their rheological properties requires considerable time, financial resources, and equipment—elements that are not readily available to contractors and design engineers in most firms. Consequently, researchers have made significant attempts to estimate the dynamic properties of asphalt mixtures on the basis of their binder and aggregate properties. This study attempts to add to existing knowledge in the area of modified asphalt mixture by presenting data from 36 different mixtures produced from 9 different modified binders, all tested for their rheology, rutting, and fatigue resistance. A set of simple models is offered to quantify the relationship between binder properties and mixture properties including the complex shear modulus G*, rutting, and fatigue life. G* of modified mixtures could be represented by a simple power law function of G* of modified binders. The change in the binder rutting rate of mixtures is approximately 20% that of binders. Also shown is that changing the fatigue life of binders by 100% can result in a 20% change in the fatigue life of mixtures. Although the relationships are not fundamental and are entirely phenomenological, they provide good first approximation tools to quantify the effects of binders and thereby inform initial decisions regarding the importance of modified binders in pavement performance.