Mini-Review on the Application of Nanomaterials in Improving Anti-Aging Properties of Asphalt

Exposed to detrimental environmental factors, such as heat, oxygen, and ultraviolet (UV) radiation, asphalt materials are prone to hardness and brittleness, namely, asphalt aging, which leads to deteriorating asphalt pavement properties and inducing a series of road distress. Theoretical and experimental studies have demonstrated that nanomaterial modifiers are a promising solution. This review discusses the application of single, compounded, and composited nanomaterial modifiers in improving the aging resistance of asphalt. Results showed that the introduction of single nanosilica, nanotitanium dioxide, and nanozinc oxide imparts positive effects on the anti-UV aging properties of asphalt, and single nanocalcium carbonate, carbon nanotubes, and layered silicates retard the thermo-oxidative aging rate of asphalt. Moreover, the multi-dimensional nanomaterial modifiers, a compound of nanometal oxide and layered silicates, comprehensively enhance the anti-thermo-oxidative and anti-UV aging properties of base asphalt and polymer-modified asphalt. Additionally, the composited nanomaterial modifiers could exert synergetic effects on asphalt properties and be a crucial area for future research. With the addition of nanomaterial modifiers, the asphalt aging processes are restrained by arresting volatile components of asphalt and lengthening the diffusion paths of oxygen molecules into asphalt binders. Another contribution mainly derives from functional groups against oxygen, which hinder the occurrences of oxidation reactions of asphalt. Many factors, such as nanomaterial modifier types, organic modification, nanomaterial concentration, and mixing methods and parameters, have influenced the anti-aging properties of nanomaterial-modified asphalt. In addition, the compatibility between nanomaterial modifiers with asphalt and nanomaterial dispersion in asphalt and the high costs involved in using nanomaterial modifiers are critical challenges for the application of nanomaterials in improving the aging resistance of asphalt. However, with cooperation between industrial communities and research institutes, an expanding application scale of nanomaterial-modified asphalt can be expected.