Document Type: Regular Paper
Faculty of Civil Engineering, Semnan University, Semnan, Iran.
Faculty of Civil Engineering, Semnan University
Faculty of Mechanical Engineering, Semnan University, Semnan, Iran
The aim of this study was to investigate the behavior of asphalt binders modified by nano-silica and synthesized polyurethane. For this objective, firstly, the asphalt binder was modified by three different percentages of nano-silica and polyurethane. Then, asphalt binders were aged in different levels, based on test conditions. The high- and low-temperature performance were evaluated using Multiple Stress Creep Recovery (MSCR) and the Bending Beam Rheometer (BBR) tests, respectively. For the investigation of the fatigue performance at the intermediate temperature, the Time Sweep (TS) test was performed. Results indicated that nano-silica improved the performance of the asphalt binder at high temperatures and lowered the efficiency at low temperatures. The synthesized polyurethane had no effect on the high-temperature performance grade of the asphalt binder. However, it improved the low-temperature performance grade. Results of fatigue tests implied that the effect of polyurethane was better than nano-silica. The Fourier Transform Infrared Spectroscopy (FTIR) test was utilized to study chemical properties. Obtained results affirmed the presence of nano-silica and polyurethane bonds. Chemical bonds at low and intermediate temperatures, as well as physical properties and the stiffness at high temperatures, played a more important role in the performance of the asphalt binder.