Relationship between nonlinear viscoelastic behaviour of asphalt binders and deformation of mixtures

Abstract

ABSTRACT Ranking of asphalt binders based on the permanent deformation characteristics of the respective mixtures is important for designing mixtures for pavements. While various tests on binders and corresponding parameters have been suggested for ranking asphalt binders, their applicability is limited since many of these parameters fail to characterise the nonlinearity in the response of asphalt binders at high stress levels and shear rates. Parameters like the non-recoverable creep compliance () from MSCR tests and the apparent viscosity from the steady shear tests are some of the few parameters that take into consideration the nonlinear viscoelastic nature of asphalt binders. However, these parameters should be determined at an appropriate stress level or shear-rate level that is representative of the stress/shear-rate level experienced by binders in pavements. In this study, the stress/shear-rate levels suitable for obtaining and apparent viscosity were determined by characterising flow behaviour of binders and their corresponding mixtures. Three asphalt binders were used in the study. The binders were characterised by conducting creep-recovery and steady shear tests, and fitting a nonlinear viscoelastic model to the results. The permanent deformation of the corresponding asphalt concrete mixes in two different tests- dry wheel tracking test and repeated creep and recovery test were obtained from another study. It was observed that the apparent viscosity determined over a stress range and a shear-rate range correlated well with the rate of permanent deformation observed in the mixture characterisation tests.