Review on the properties and mechanisms of asphalt modified with bio-oil and biochar
Xinxing Zhou, Xinxing Zhou, Ziyang Zhang, Haopeng Wang, Meizhu Chen, Shaopeng Wu, Xu Song, Xinglin Zhou, Xinglin Zhou, Maoping Ran, Linglin Li, Guangjun Lu, Zhibin Ma
Abstract
Bio-asphalt has a great application prospect in the replacement of petroleum-based asphalt to pave and maintain asphalt pavement. However, the problems of flow-induced crystallization and phase separation caused by flow-induced crystallization had severely restricted its application. This paper describes the progress of research on preparation, property evaluation and phase separation mechanism of bio-asphalt. The advantages and disadvantages of preparation methods of bio-asphalt are states. The fundamental physical and rheological properties of bio-asphalt are investigated, especially for flow-induced crystallization. There exists obvious flow-induced crystallization because bio-asphalt is rich in waxes that crystallize easily. Owing to the existence of excess biochar, bio-asphalt appears phase separation. A brief review of the effect of bio-oil and biochar on asphalt volatile organic compounds (VOCs) is presented. Research find that bio-oil/biochar are not only replenish the light components of asphalt, but also improve the flow-induced crystallization and phase separation of bio-asphalt. There exists synergistic effect of biochar and bio-oil in asphalt modification. Moreover, biochar can improve the durability of bio-oil modified asphalt, but excessive addition of biochar to bio-oil modified asphalt can cause phase separation. Adding an appropriate amount of bio-oil and biochar to asphalt can improve its high-temperature resistance, low-temperature crack resistance, and system compatibility. • Crystalline wax in bio-oil is the key of flow-induced crystallization of bio-asphalt. • The surface organic functional groups of biochar are the main inducement of VOCs adsorption. • Both bio-oil and biochar can lead to the change of four components of asphalt.