Consideration of Elastic and Viscous Components of Rheology Relating to the Permanent Deformation of Hot Mix Asphalt Pavements

The minimization of deformation in hot mix asphalt is an important aspect of pavement design. The performance of asphalt mixtures is strongly influenced by both the behavior of aggregate particles and the rheology of the binder. The resulting rheology of the composite material — hot mix asphalt — is significantly shifted from that of the asphalt binder. Rheology of binders and mixtures has been evaluated by testing, which includes Dynamic Shear Rheometer (DSR) and Uniaxial Cyclic Modulus (UCM) measurements, respectively. Master curves of stiffness modulus are constructed using principles of time-temperature superposition that consider both the elastic and viscous components of the modulus. The Federal Highway Administration (FHWA) Accelerated Load Facility (ALF) study has provided an important source of data since materials that were evaluated represented wide ranges in performance. Data from the rheology measurements have been compared to deformation performance of pavements tested at a constant temperature. The determination of the high temperature viscosity properties versus plastic deformation and straining are discussed. A practical framework for the extraction of material parameters from cyclic frequency sweep testing for use in specifications for quantifying the quality of asphalt binders and mixtures is presented.