Observed deviations from isotropic linear viscoelastic behavior of asphalt concrete through modal testing

The complex Young's moduli, complex shear moduli and complex Poisson's ratio of a beam shaped asphalt concrete specimen have been characterized through low strain (∼10−7) frequency response function measurements. The assumption of isotropic linear viscoelastic behavior has been applied and investigated. The results indicate that the asphalt concrete specimen agree with the isotropic linear viscoelastic assumption at low temperatures and high frequencies (>10 kHz at 0 °C), but at higher temperatures and lower frequencies, discrepancies from isotropic linear behavior are shown. The dynamic shear moduli calculated from the estimated Young's moduli and Poisson's ratio of the asphalt concrete specimen are overestimated for frequencies and temperatures often applied to pavements.