| Universal viscoelastic constitutive model has a wide application on describing the constitutive relation for asphalt binders under different loading modes. Up till now, the viscoelastic constitutive model of asphalt binder has been received attentions in since past few years and a variety of viscoelastic constitutive models were present. However, the existing viscoelastic models can only simulate single or multiple mechanical behaviors, which are lack of universality; meanwhile, these models cannot be applied to under both dynamic and static loading modes. Although the generalized viscoelastic model can reflect the dynamic and static viscoelastic properties of asphalt binder, the model is complex, thus it is not convenient to practical application. Consequently, it is crucial to establish a simple and universal viscoelastic model for prediction of mechanical properties of asphalt binders and pavement design.In order to solve these problems, initially, the viscoelastic characteristics of asphalt binders under dynamic and static loading were studied. The changing law of complex modulus, phase angle, storage modulus and loss modulus in frequency domain under various temperatures and loading conditions were analyzed; yet, the viscoelastic parameters master curves were established to investigate the changing law of viscoelastic properties of asphalt binders within wide frequency range. At the meantime, the compliance modulus and relaxation modulus in time domain were analyzed. It lays a solid foundation for the establishment of universal viscoelastic constitutive model of asphalt binder.Secondly, the viscoelastic model is identified based on complex dynamic viscoelastic characteristics, which includes the classical rheological model identification and the fractional model identification. The number of basic elements and the combination of the mode were studied afterwards. As a result, the model elements and ways of combination were proposed.Finally, based on the separated dynamic test data, the separated static test data and combination of dynamic and static test data respectively, the parameters of universal viscoelastic model of asphalt binders were identified and fitted, then the optimization criterion of the model parameters identification was determined. Besides, mastic were chose to verify the applicability of universal viscoelastic model of asphalt binder under similar research methods.This research introduces the model identification and parameter identification of the universal viscoelastic constitutive model of asphalt binder, which provides a theoretical foundation for determination of the viscoelastic model and prediction of mechanical properties of asphalt binder. Besides that, it offers reference value for the constitutive model of other viscoelastic materials. |
