Page 53 - Mechanics of Asphalt Microstructure and Micromechanics

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46 Ch a p t e r w o

Elastic Modulus (GPa) Standard
Rock Type Maximum Minimum Mean Deviation
Granite 100 6.41 52.7 24.5
Diorite 112 17.1 51.4 42.7
Gabbro 84.1 67.6 75.8 6.69

Diabase 104 69.0 88.3 12.3
Basalt 84.1 29.0 56.1 17.9
Quartzite 88.3 36.5 66.1 16.0
Gneiss 82.1 28.5 61.1 15.9
Sandstone 39.2 0.62 14.7 8.21
Limestone 89.6 4.48 39.3 25.7
Dolostone 78.6 5.72 29.1 23.7
TABLE 2.1 Typical values of elastic modulus of intact rocks (from AASHTO HB-17, 2002).

While rocks may be modeled as isotropic/anisotropic linear elasticity, linear visco-
elasticity, plasticity, and viscoplasticity, how these different models affect the mixture
properties (especially the anisotropy) needs assessment.
Table 2.2 presents the typical Poisson’s ratios for these rocks. For the same type of
rocks, porosity may vary. In addition, when particle sizes become smaller, the porosity
typically decreases as well. Table 2.3 presents the ratios between the maximum and
minimum moduli of different rocks. Table 2.4 presents the typical values of the uncon-

Poisson’s Ratio Standard
Rock Type Maximum Minimum Mean Deviation
Granite 0.39 0.09 0.20 0.08
Gabbro 0.20 0.16 0.18 0.02
Diabase 0.38 0.20 0.29 0.06
Basalt 0.32 0.16 0.23 0.05
Quartzite 0.22 0.08 0.14 0.05
Gneiss 0.40 0.09 0.22 0.09
Sandstone 0.46 0.08 0.20 0.11

Limestone 0.33 0.12 0.23 0.06
Dolostone 0.35 0.14 0.29 0.08
T ABLE 2.2 Typical values of Poisson’s ratio of intact rocks (from AASHTO HB-17, 2002).