Application of the theory of viscoelasticity to evaluate the resilient modulus test in asphalt mixes

This paper deals with the analysis of indirect tensile resilient modulus (IT RM) tests for asphalt mixes. In Brazil, for instance, asphalt mix stiffness is obtained from a classical elastic analysis of the referred test, which may not be suitable for a viscoelastic material. A method is proposed to compare IT RM results from classical experimental analysis and from tests simulated with viscoelastic models. Four different asphalt mixes with four different binders were analyzed using IT RM tests, with varying loading time and temperatures. Complex modulus (E∗) tests were performed to characterize the linear viscoelastic behavior of the investigated materials on a wide range of temperature and frequency. 2S2P1D model and general Kelvin Voigt (GKV) model were then fitted to the E∗ data. IT RM tests results were calculated using an analytical method and the viscoelastic GKV models obtained for the four mixes. Differences found for the stiffness results obtained from the distinct procedures are discussed, and pavement analyses showed that such differences substantially affect the structural response. This is to be expected as a consequence of the missing of fundamental considerations on the material behavior.