Page 372 - Mechanics of Asphalt Microstructure and Micromechanics

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364 Ch a p t e r e n

determine the film thickness. The asphalt content can also be determined using an al-
ternative approach that is based on modeling the particle-particle contact with a binder
layer. As the binder layer will affect the plastic/permanent deformation of particles in
contact, this layer thickness will be directly linked to the rutting performance of the
mixture. On the other hand, when the asphalt film thickness is too small, wearing of the
asphalt binder will reduce its fatigue properties.
Step 4: Performing a Digital Test to Predict the Performance
Once the aggregate gradation and asphalt content are determined, the mechanical
behavior of the mixture can be evaluated with, for example, the dynamic modulus test
or the indirect tensile test using the discrete element method (DEM) and the finite ele-
ment method (FEM), or the digital specimen and digital test techniques. In this ap-
proach, the characterized binder properties (needed in modeling the contact and the
heterogeneous mixture), aggregate shape (contact curvature), and contact asperity can
be directly incorporated in the tests.

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