Page 43 - Mechanics of Asphalt Microstructure and Micromechanics

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36 Ch a p t e r w o

The considerable evidence strongly suggests the suitability of the modified cross
model in describing the pseudoplastic flow behavior of pure bitumen at a wide range
of stress levels.
2.1.7 Linear Viscoelasticity
At other temperatures, the binder may be described as linear elastic or non-linear elastic
material.
Based on an experimental study by Cebon and his colleagues, they generalized the
deformation mechanism in Figure 2.1. While this information is very useful, it also in-
dicates the complexity of the deformation mechanism of asphalt binder. This complex-
ity presents tremendous challenges for modeling and simulating the behavior of as-
phalt binder and AC. In other words, a universal model that covers all the temperature
ranges and strain rate ranges may not be realistic. Transitional properties and viscoplas-
tic properties were also modeled by Cebon and his colleagues (Cheung and Cebon,
1995, 1997a, 1997b).

2.1.8 Film Thickness Effect
When asphalt binder is sandwiched between two aggregate particles, its mechanical
properties will be affected by the particle-binder interface friction. This can be modeled
as plane strain problem as illustrated in Figure 2.2 (Cheung and Cebon, 1997b). For the

FIGURE 2.1 Deformation mechanism of asphalt binder (Cheung and Cebon, 1997a).