Microstructure of nanosilica modified binder by atomic force microscopy

Abstract

In this paper, the effect of nanosilica (NS) on the physical properties as well as aging on the morphology of asphalt binder was investigated. Asphalt binder penetration grade 60/70 (PEN 60/70) was modified with NS at concentrations of 1% to 5% by weight of binder. Scanning electron microscopy (SEM) was used to have a visual evaluation of Nanosilica dispersion. The physical properties tested include is softening point, penetration, ductility, viscosity and storage stability. Temperature susceptibility was evaluated using penetration index (PI) and penetration viscosity number (PVN). Nanosilica modified binder (NSMB) were aged using the rolling thin film oven test (RTFO) and pressure aging vessel (PAV). The morphology of the virgin asphalt binder and NSMB before and after aging was characterized by tapping mode atomic force microscopy (AFM). From the physical properties test, the addition of NS was found to improve the asphalt binder properties and can resist high temperature susceptibility. The results of the AFM imaging showed that the addition of nanosilica in asphalt binder improved its surface stiffness. The overall surface stiffness of the asphalt binder after aging also increased. It can be concluded from this study that 2% to 4% of NS gave the optimum performance for the binder.