Laboratory Simulation of Warm Mix Asphalt (WMA) Binder Aging Characteristics

Abstract

As warm asphalt has been gaining increasing popularity in the recent years, there are still several characteristics about warm asphalt that are unknown. While several studies have been conducted to study the performance of warm asphalt mixtures, aging characteristics of warm asphalt binders are not known in great detail as the technology is relatively new, and there are no old pavements to study the aging behavior of warm asphalt. This paper presents the results of a study conducted to simulate the aging of warm asphalt binder in the laboratory by preparing asphalt mixtures containing two different binder sources and three different warm asphalt additives (Control, Asphamin® and Sasobit®). The mixtures were artificially aged in the oven, and the binders were extracted for testing. The binders extracted from freshly prepared samples were considered being short term aged binders and binders extracted from oven aged mixtures were considered being long term aged binders. Results of several tests (e.g., viscosity, high and low temperature properties, Gel Permeation Chromatography, etc.) are presented in this study. The results indicated that the binders extracted from the warm mix asphalt (WMA) had significantly lower aging index (ratio of the viscosity of extracted binders to original binders) compared to the binders extracted from control hot mix asphalt (HMA). It was also observed that the binders extracted from the WMA had aged significantly lower compared to binders extracted from control HMA. The results indicated that the warm asphalt additives did not have any significant effect on the fatigue cracking parameter (G*.sin δ) or the creep stiffness of the binders. However, Asphamin® significantly increased the m-value of the binders.