The New Proposed Rheological Properties of Asphalt Binders: Why are they Required and how do they Compare to Conventional Properties

As a result of the research conducted for the Strategic Highway Research Program (SHRP), a set of new testing methods to characterize the rheological, failure, and durability properties of asphalt binders has been developed. These methods utilize testing devices that are either completely new or have been used before only for research purposes. The methods also call for measuring mechanical response parameters that are not very common for asphalt pavement engineers nor for many asphalt producers. The purpose of this paper is to discuss the following points: 1) the viscoelastic nature of asphalts and its relation to pavement performance; 2) the types of conventional measurements that are used now and the fundamental problems with them; 3) the concept behind selecting the new test methods and the new characteristic properties; and 4) how the new measured properties compare to the conventional properties. The paper addresses these points by providing theoretical-conceptual background about the conventional and new tests and by comparing new and conventional data measured for a large number of asphalts that vary in their source and their grade. The comparison clearly identifies the advantages of the new testing methods and the need to implement the proposed testing and specification system.