A Sustainable Industrial Waste Management Solution: Application Of Silica Fume To Enhance Asphalt Binder Rheological Properties
Abstract
This thesis investigates the practical feasibility of using silica fume, an industrial waste material, to enhance the rheological properties of asphalt binder. It has been widely reported that asphalt binder oxidation reduces the service life of asphalt pavement by negatively impacting its rheological properties. When asphalt binder is oxidized, its viscoelastic properties are diminished; this can be evidenced by the reduction in asphalt phase angle as measured through dynamic shear and torsion tests. This can lead to a more brittle pavement, which is more prone to cracks due to thermal stress and traffic loading and leads to premature pavement failure. In this thesis, the effectiveness of the application of silica-fume-based additives to reduce asphalt oxidative aging is investigated. It is hypothesized that fine-graded silica fume with nano- to micro-level particle size can be used to reduce asphalt oxidation. To test this hypothesis, various percentages of silica fume were introduced to base binders; then a series of experiments in binder and mixture level was conducted to evaluate the effects of silica fume addition. In the binder level, silica fume was concentrated in asphalt binder with percentages of 2%, 4%, and 8% for both aged and non-aged samples. A rotational viscometer (RV) was used to study the effects of silica fume on high-temperature properties of asphalt binder. FTIR analysis was used to determine the chemical compounds of silica-fume-modified asphalt matrix. The Marshall stability test was used to evaluate the stability of the asphalt mixture in the presence of silica fume. Analysis of the experiment results showed that silica fume reduced the asphalt aging index significantly; in addition, the temperature susceptibility of asphalt binder was reduced as the percentage of silica fume increased. The positive effect of silica fume on base asphalt’s rheological properties could be attributed to the high surface area of the silica fume accompanied by its granular particles with high polarity.