Review on the self-healing of asphalt materials: Mechanism, affecting factors, assessments and improvements

Fatigue cracking is one of the main diseases that affect pavement durability. Understanding the relationship between the self-healing ability and fatigue life of asphalt materials from the molecular level will aid in the preventive maintenance and improvement of asphalt pavement. This work analyzes the research progress on the self-healing of asphalt and asphalt mixtures, including self-healing mechanism, influencing factors, evaluation methods, and improvement aspects. Factors affecting the self-healing performance are categorized as internal, such as molecular structure, asphalt motion and diffusion, asphalt viscoelasticity, and thixotropy, and external, such as humidity, temperature, induction conditions, and time. The self-healing performance can be adjusted by optimizing the chemical composition of the asphalt materials, changing the preparation method, and ensuring the spontaneous structure formation to achieve the intellectualization of the intrinsic material. This work sheds light on the design of materials and structures for durable pavement from the perspective of the self-healing behavior of asphalt materials.