Viscoelastic Model of Asphalt Mixtures under Repeated Load.

Repeated loading test has been widely used to simulate the true stress state of pavement materials under traffic loading with more accuracy. In this paper, a half-sinusoidal load with 0.1-s loading duration and 0.9-s rest period was selected to simulate the dynamic traffic loading. A generalized Kelvin viscoelastic model of asphalt mixtures based on linear-superposition principle under repeated load is developed. The Prony-series coefficients of the generalized Kelvin model are obtained by the static creep tests of AC-13C and AC-20C unmodified and modified asphalt mixtures. Then, the strain of AC-13C and AC-20C asphalt mixtures under repeated load could be predicted by the proposed viscoelastic model. Comparing the predicted strain obtained by retardation-time spectrum having and not having fixed time with the measured strain, it is believed that the retardation-time spectrum covering both the loading and unloading time processes should be selected in predicting strain of asphalt mixtures under repeated load. The proposed generalized Kelvin viscoelastic model under repeated load allows for prediction of permanent deformation of asphalt mixtures as well as rutting in asphalt pavement. [ABSTRACT FROM AUTHOR]