Characteristics of highly reflective and fluorescent TiO2 quantum dots modified asphalt binder

Abstract

With strong absorption of solar irradiation, black asphalt material contributes to high pavement temperature, which subsequently speeds up pavement deterioration and shortens its service life. TiO2 quantum dots (QDs) as an interesting zero-dimensional nanocrystal, feature exceptional reflective and fluorescent characteristics. This study is dedicated to design and characterize highly reflective and fluorescent TiO2 QDs modified asphalt binder for cool pavement application. TiO2 QDs modified asphalt binder was prepared by incorporating TiO2 QDs into asphalt binder with varied sizes of 5–20 nm and concentrations of 5–20%. The results unveil that solar reflectance of TiO2 QDs modified asphalt binder reaches up to 15% compared to 3% of traditional asphalt binder. Meanwhile, fluorescent intensity of asphalt binder is enhanced by up to 10.9 times after adding TiO2 QDs. Additionally, as content of TiO2 QDs rises, the penetration and ductility of modified asphalt binder decrease while softening point and viscosity of modified asphalt increase. Superpave performance characterization of asphalt binder demonstrates that TiO2 QDs modified asphalt binder exhibits superior rutting resistance and inferior low-temperature cracking resistance as well as fatigue resistance than conventional asphalt binder; TiO2 QDs modified asphalt binder exhibits the same performance grade with base binder except asphalt binder with 30% TiO2 QDs. Chemical analysis has revealed that TiO2 QDs modified asphalt binder is modified through physical modification process. Moreover, it is found that the addition of TiO2 QDs imposes negligible impact on thermal properties of asphalt binder. The research outcome fastens the utilization of TiO2 QDs modified asphalt binder as a promising cool pavement technology.