Page 119 - MODELING OF ASPHALT CONCRETE
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Complex Modulus Characterization of Asphalt Concr ete 97
A study by Pellinen and Witczak (2002a) suggests similar results. The overall linear
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correlation between measured dynamic modulus |E | and SST-shear modulus |G |
values within the linear viscoelastic region for the various dense graded mixtures was
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R = 0.87. Figure 4-7(a) shows that the deviations in test results are greater at low- and
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high-temperature extremes, greatly exceeding the stiffness ratio of |E | ≈ 2.5 to 3|G |,
which is based on theoretical equivalency using Poisson’s ratio values from 0.2 to 0.5.
The overall linear correlation of the phase angle values from dynamic modulus and
2
SST-shear modulus measurements was R = 0.61 and, at best, is indicative of a fair
correlation. More importantly, it can be observed from Fig. 4-7(b) that there is no direct
FIGURE 4-7 Correlation of axial and shear (a) modulus and (b) phase angle. (Pellinen and
Witczak 2002a, with permission from National Academies Press.)
