Rheological behavior of asphalt binders and fatigue resistance of SMA mixtures modified with nano-silica containing RAP materials under the effect of mixture conditioning

Abstract

Due to the environmentally associated issues regarding the construction or rehabilitation of asphalt pavements with merely virgin materials, researchers have proposed the re-utilization of the reclaimed asphalt pavement (RAP) materials. However, their adoption in asphalt pavements is detrimental to the fatigue performance of asphalt pavements. For this, modifying asphalt binders with nanoparticles has been one of the successful choices among researchers. In this study, different compounds of asphalt binders and stone matrix asphalt (SMA) mixtures containing 20%, 30%, 40%, and 50% RAP materials modified with 2%, 4%, and 6% nano-silica were prepared. Moreover, the rheological behavior of each mix was evaluated using several tests, including rotational viscosity (RV) considering the flow activation energy (FAE) method, frequency sweep, Multiple Stress Creep Recovery (MSCR), Linear Amplitude Sweep (LAS), and Bending Beam Rheometer (BBR). Besides, the fatigue performance of aged SMA mixtures was investigated using the four-point beam fatigue (4 PB) test. The results indicated that the temperature susceptibility of binders was decreased by the addition of nano-silica and RAP binder. Also, according to the MSCR and frequency sweep tests results, the rutting resistance of modified binders with the RAP binder was superior to that of the base binder. Besides, due to the establishment of a network by nano-silica within the structure of the asphalt binder in which the functional groups of asphalt binder interact with nanoparticles, the modified binders with RAP binder outperformed their unmodified counterparts regarding the fatigue life. Also, aging had a less detrimental impact on the fatigue life of the RAP contained SMA mixtures. However, the low-temperature performance of binders was degraded by the addition of nano-silica.