Analysis of Dynamic Effects in Complex Modulus Characterization of Asphalt Concrete

Asphalt concrete is commonly characterized in the frequency domain by exposing material specimens to harmonic excitation under a range of frequencies and temperature levels. According to current test protocols, dynamics (inertia) effects are disregarded when interpreting raw test results. In this context, the main objective of this paper was to develop and present analytical expressions suited for the interpretation of complex modulus test results of asphalt concrete, including dynamic effects. The secondary objective of the paper was to apply the new formulation in a synthetic case study to demonstrate and quantify dynamic effects for a common test setup. In part, these objectives were motivated by the capabilities of modern testing gear to perform at very high frequencies—up to 1,000 Hz. It is concluded that dynamic effects can be ignored when following current complex modulus test protocols, as they refer to a maximum test frequency of 25 Hz. However, when modern high-performance testing gear is utilized, dynamic effects should not be ignored, especially for excitation frequencies above 100 Hz in combination with high test temperatures.