Asphalt Binder Parameters and their Relationship to the Linear Viscoelastic and Failure Properties of Asphalt Mixtures

Asphalt concrete is a non-homogenous viscoelastic material; its behavior depends on the properties of the asphalt binder and the aggregate skeleton. The two major distresses in flexible pavements, fatigue cracking and rutting, have different mechanisms in that the way binders and mixtures behavior are related differ. Further complicating the issues is that distresses in asphalt pavement are dependent on climate, pavement structure, and traffic loads, in addition to factors such as properties of the asphalt mixture itself. Hence, to characterize the multiscale mechanics associated with binder to mixture behaviors, researchers characterized the fatigue and rutting resistance of asphalt binders and mixtures in the laboratory, and established specifications related to how asphalt mixtures would perform in the field.

This dissertation tackles the linkages across length scales with respect to rutting and cracking. Through the literature reviewed, studies regarding the linear and non-linear viscoelastic properties of asphalt mixture and the corresponding bitumen were identified. There was a wealth of data in this area. In addition, the relationship between the laboratory mixture short-term aging and the binder aging conditions were studied, characterized and analyzed.

The literature review showed that there exists a shortage of knowledge that directly examines the relationships between the binder nonlinear viscoelastic damage behaviors and mixture performance. Addressing this knowledge gap is the basic objective of this research. Specifically, the relationships between the non-recoverable creep compliance at 3.2 kPa (Jnr3.2) and the percent of elastic recovery (R3.2) from the multiple stress creep and recovery (MSCR) test and mixture rutting; and between mixture fatigue and binder linear amplitude sweep (LAS) were studied.

Finally, an aging study was performed to ensure that the binder tests properties reflect the condition of the binder during the mixture test when evaluating binder-to-mixture properties. The propensity to oxidize measured by calculating the aging ratio of various aged conditions (RTFO, PAV, and STOA) were gathered and analyzed.