Complex modulus and complex Poisson’s ratio from cyclic and dynamic modal testing of asphalt concrete

• Linear viscoelastic properties of asphalt concrete from cyclic and modal testing are compared.
• Strains from the modal testing are approximated for the different temperatures.
• Modal testing results in higher absolute value of the complex modulus compared to cyclic tests.
• Cyclic and modal testing resulted in similar complex Poisson’s ratio master curves.

The complex moduli and complex Poisson’s ratio of two cylindrical asphalt concrete specimens have been determined through modal testing in this paper. These results have been compared to cyclic tension–compression measured complex moduli and complex Poisson’s ratio of asphalt concrete specimens with different dimensions. The modal testing has been performed by measuring frequency response functions of the specimens using an impact hammer and an accelerometer. The material properties have been characterized by matching finite element computed frequency response functions to the measurements. The results of the different specimens show that the modal test systematically give a slightly higher absolute value of the complex moduli compared to the cyclic testing. The differences are most likely a result of the different strain levels applied in the two test methods. However, the modal and cyclic tension–compression testing resulted in similar values of the complex Poisson’s ratio for the two different asphalt concrete mixtures despite the different applied strain levels.