The effect of long-term aging on the rheology of warm mix asphalt binders

Abstract

The study described in this paper aims at quantifying the long-term aging effects on the rheological properties of warm mix asphalt (WMA) binders. Under the scope of this study, the authors focused on four warm mix asphalt additives: Sasobit, Rediset, Cecabase and Evotherm, of which the first one is an organic and the latter three are synthetic additives. The rheology of the aforementioned additives added to a PG 64-22 binder were studied using a frequency sweep test performed over a range of ten different loading frequencies and three different temperatures with different degrees of exposure to oxidative aging.The paper proposes a more efficient methodology for developing master curves for asphaltic materials based on joint estimation of the model parameters that eliminates any possible propagation of biases from one model to the other. The developed master curves accommodate the simultaneous quantification of the effect of loading time, temperature and aging on the rheological properties of the WMA binder.The paper finally addresses the effect of aging on different WMA binders. Results indicated that the Rediset WMA binder had the lowest shear modulus, followed by the Evotherm, Cecabase and Sasobit WMA binders. However, a different rate of gain trend was observed in the modulus values where, again, Rediset was slowest of all but followed by Sasobit, Evotherm and Cecabase binders. This implies that, of all the binders investigated in this study, the Sasobit WMA binder will have a significantly lower modulus over time as compared to the control PG 64-22 binder and the Rediset WMA binder will have the lowest modulus in the short-term as well as over time.