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Modeling of Asphalt Concr ete 5

the global stress-strain behavior of asphalt concrete in predicting the pavement
performance. The challenge in this combined approach is to determine the material
properties at the proper scales, as it is expected that some material properties are scale
dependent.

Virtual Testing of Asphalt Concrete
One of the fastest growing techniques that can aid asphalt concrete modeling is the
imaging technique, including digital imaging, laser, and x-ray tomography, to name a
few. These techniques allow engineers to view and construct two- and three-dimensional
microstructures of the mixture. The imaging techniques can be combined with advanced
models of asphalt concrete and provide the tools to perform virtual testing of asphalt
concrete. In this approach, virtual microstructures of asphalt concrete are generated
from the imaging technique, and virtual testing is conducted on the virtual microstructure
using the advanced numerical models. These virtual testing techniques will help asphalt
material and pavement engineers to evaluate the effects of any change in the component
material properties on the mixture behavior and performance without any laboratory
testing. The virtual testing will also be an efficient tool in undergraduate and graduate
asphalt materials courses to demonstrate the effects of changing testing conditions and
mixture design parameters on the behavior and performance of asphalt concrete.

Organization Summary
Part 1 (Chap. 2) is dedicated to asphalt binder modeling. Various aspects of the stiffness
characterization of asphalt concrete are described in Part 2 (Chaps. 3 through 6). Part 3
(Chaps. 7 to 9) presents different constitutive modeling approaches for asphalt concrete.
Part 4 (Chaps. 10 and 11) examines models for rutting. Part 5 (Chaps. 12 and 13)
addresses models for fatigue cracking and moisture damage. Last, Part 6 (Chaps. 14
and 15) addresses models for low-temperature cracking.
Note that this book does not necessarily describe all the models that are currently
available within each aspect of asphalt concrete modeling (as outlined in the six parts,
accordingly). However, it should provide sufficient information about a wide range of
models that are available. The following descriptions provide a summary of the contents
of each part.

Part 1—Asphalt Binder Rheology
Part 1 of this book deals with issues pertaining to asphalt binder rheology. The historical
use of rheological indices in the asphalt industry is discussed to provide perspectives
on the development and rationale for the findings from the SHRP project. The influence
of binder properties on mixture performance is discussed. Background on polymer
modification of asphalt binders is presented and, subsequently, an argument for the
enhancement of asphalt binder performance by adding polymer-modifying agents is
given. A rheological modeling approach capable of capturing the beneficial aspects of
polymer-modified binders is presented along with results from an accompanying
experimental study. Since the focus of this book is the modeling of asphalt concrete,
only one chapter is allotted to a discussion of asphalt binders.