The effects of moisture susceptibility and ageing conditions on nano-silica/polymer-modified asphalt mixtures

This study investigates the performance characteristics of polymer-modified asphalt mixture (PMA) with the addition of nano-silica particles. Polymer-modified asphalt, PG-76, was mixed with nano-silica at concentrations of 0%, 2% and 4% by weight of asphalt binder. Asphalt mixture tests such as moisture susceptibility, resilient modulus and dynamic creep were conducted to evaluate the performance of PMA mixed with nano-silica under various ageing and moisture susceptibility conditions. During the mixing process, the binders were kept at 160 °C and blended using a shear rate of 1500 rpm (rpm) for approximately 1 h. Microstructure examinations of the asphalt binders were then carried out using scanning electron microscopy (SEM). The SEM images show that the nano-silica particles disperse well in the asphalt binder matrix. Nano-silica reduces the susceptibility to moisture damage and increases the strength of asphalt mixes. It is also observed that fatigue and rutting resistance are enhanced for PMA mixed with nano-silica particles. Ageing index values show that the susceptibility to oxidative ageing is significantly reduced with the increase of nano-silica content, particularly in the case of long-term ageing. The addition of 4% nano-silica with PMA appears to have the greatest potential for beneficial modification of the binder.