ABSTRACT
The AASHTO: TP 79-10 standard stipulates the test procedure for the measurement of dynamic modulus of bituminous mixtures. In this investigation, dynamic modulus data of two types of bituminous concrete mixtures (an unmodified binder and crumb rubber modified binder) are studied using TP-79-10 protocol. The experiments showed that the total strain decreased with time at higher temperatures and at lower frequencies. Also, for some mixtures, the phase lag decreased with decreasing frequency. While many studies reported such observations, these anomalous results are normally ascribed to the errors in measurement mechanisms and have not been explained within the context of the material behavior. Here it is shown that Burgers’ viscoelastic model exhibits these phenomena. Also, the need for data processing techniques using the complete loading history and a viscoelastic model is emphasized.
