Investigation of the Performance of Neat and Modified Asphalt Binders

Abstract

The Superpave binder specifications are performance-based criteria for binder selection for use in hot-mix asphalt mixtures. However, these specifications may not be applicable to modified binders. This research investigates the a new method for determining hot-mix asphalt mixing and compaction temperatures as well as the performance of neat (unmodified) and modified binders of the same performance grade. The first phase of the research focuses on determining mixing and compaction temperatures for hot-mix asphalt mixtures. Modified binders are shear rate and temperature dependent and the conventional methods of determining mixing and compaction temperatures can yield extreme results. The Zero Shear Viscosity theory is used as an alternative method to determine hot-mix asphalt mixing and compaction temperatures. The results reveal that the method is applicable to determining mixing and compaction temperatures for hot-mix asphalt mixtures containing modified binders, but additional work is needed in order to make the method applicable to neat binders. The second phase of the study investigates the performance of hot-mix asphalt mixtures containing neat and modified binders. Laboratory tests were performed on similar mixtures that contained neat and modified binders. Simple performance tests, such as accelerated rutting, flexural beam fatigue, and indirect tensile indicate that modified binders may contribute to improved hot-mix asphalt resistance to various distresses. Overall, performance-graded binders of the same grade appear to offer similar performance regardless of the high temperature at which the binder meets the high temperature specification.