Effect of Steam Aging on Performance-Related Properties of Hot Asphalt Mixture

Abstract

This study presents a new laboratory technique for binder aging by using a steam cooker. This new technique is used to study the effect of steam and heat on asphalt during storage and asphalt pavement during its service life. Five steam-aging durations (, 15, 3, 45, 6, and 75 min) with four steam-aging stages at diffrent pressures and temperatures for each stage are selected to investigate the physical and rheological properties of steam-aged asphalt binders. The steam-aged asphalt binders are subjected to a short-term aging process by means of a rolling thin-film oven test (RTFOT) in order to investigate the influence of aging on steam-aged asphalt binder properties after aging. Bituminous binder properties are investigated by both physical and rheological methods. Tensile strength tests were used to select the suitable stage for the research. In general, the physical test results demonstrate prominent increments in softening point and viscosity, and decrements in penetration for steam-aged binders compared with nonaged binders. This study adopts a time-sweep (TS) test method to study the fatigue phenomenon under a control strain mode using a dynamic shear rheometer (DSR). Fatigue life of asphalt binders is defined using the traditional approach based on number of cycles required to cause to cause failure and reduction in stiffness. Temperature-sweep tests using a dynamic shear rheometer (DSR) are used to predict the asphalt grade after aging. Indirect tensile tests are done to study the effect of aging/moisture on the performance of asphalt mixtures. The main objectives of the study are to study the effect of pressure and temperature on asphalt binders by using new technique and to determine the sensitivity of steam-aging (LPSA) on asphalt binders and mixtures.