Effect of laboratory oxidative aging on dynamic shear rheometer measures of asphalt binder fatigue cracking resistance

Abstract

Long-term aging can significantly affect the fatigue property of asphalt pavements. The influence of aging on fatigue resistance of asphalt binder has not been fully understood and unified conclusions are lacking. In this work, the effect of laboratory oxidative aging on fatigue damage resistance and linear viscoelastic (LVE) parameters of asphalt binder is studied. Tests included the temperature-frequency sweep, linear amplitude sweep (LAS) testing and time sweep from the output of dynamic shear rheometer (DSR). Different undamaged parameters (e.g., Glover-Rowe parameter (GRP), dynamic shear modulus |G*| at 64 °C, |G*|·sinδ (δ is the phase angle)) have been proposed as the indicators of aging sensitivity of the asphalt binder and are discussed. The fatigue test results are interpreted under different aging levels by using Simplified viscoelastic continuum damage (S-VECD) analysis. The trends of LVE parameters with increasing aging levels are very intuitive and show a tendency to increase in value with aging. The number of cycles to failure (Nf) shows a less intuitive trend than the LVE parameters. The existing failure criteria GR works well for the Nf prediction for highly aged materials. From the results of measured and predicted Nf from time sweep and LAS tests, fatigue damage resistance appears to increase with long-term aging at low strain levels (less than 7% strain levels in this work). When the aging level continues increasing, the fatigue resistance eventually declined in most cases evaluated. The objective of this study is to evaluate the fatigue resistance of asphalt binder under different aging levels by using various parameters and failure criteria.