Rheological Characteristics of Nano Silica Modified Asphalt Binder Material

A critical research area overlooked in previous studies on nano-silica material is the understanding of how its physical characteristics influence its final behavior as a composite when added to the asphalt binder. This study aimed to understand the feasibility of modifying the nanosilica with asphalt binder based on the asphalt binder characteristics. 60/70 penetration grade asphalt cement was prepared by adding (2%, 4% and 6%) of nanosilica by weight of asphalt. Properties of nanosilica material and asphalt cement were first examined. To prepare the modified asphalt binder was heated at 140°C, blended by mechanical mixer at a speed of 2000 rpm for different mixing durations (30 to 60) minute. The modified asphalt binder was examined for rheological properties including penetration grade, softening point temperature, penetration index, Brookfield rotational viscosity and ductility test. Results shows that the modified asphalt binder stiffness increases based on rheological properties and sensitivity of temperature decreases with increasing nanosilica percentage. A 4 % nano silica by asphalt weight enhanced the conventional properties of the modified asphalt binder and became proper in hot weather conditions. While ductility of modified asphalt decreases with increasing nano silica percentage, due to stiffness and agglomeration increased. Finally, longer mixing time to more than 60 min had an adverse effect on the ductility property and lead to agglomeration of nanosilica modified asphalt binder.