Recent development and application of natural fiber in asphalt pavement

Asphalt pavement significantly burdens the environment and is easily threatened by many diseases. Compared with synthetic fiber, natural fiber is not harmful to the environment and is an abundant resource. As a thin and filamentous material, natural fiber can effectively reduce asphalt pavement cracking and aggregates loosening disease, prolonging the service life of the pavement. This paper reviewed the latest research progress on natural fiber in asphalt pavement. Firstly, the basic information of natural fiber was described, including fiber types, composition, physical and mechanical properties, heat resistance, oil adsorption, dispersity and durability. Afterward, the application methods of natural fiber were introduced, including the extraction of natural fiber, surface treatment methods and preparation of mixtures. Subsequently, the high-temperature rheological, low-temperature, fatigue and shear strength properties of natural fiber modified asphalt binder were analyzed. Then, the pavement performances of natural fiber modified asphalt mixtures were investigated, including the high-temperature, low-temperature, water stability and fatigue performances. Besides, the reinforcement mechanism of natural fiber was also emphasized, including the effects of adsorption asphalt and three-dimensional spatial network structure. Finally, the engineering case and cost analysis were presented. Besides, a direction worthy of further research was provided. In conclusion, natural fiber was a friendly and promising modifier.