A Review on Using Ultrasonic Waves to Evaluate the Characteristics of Asphalt Pavement

Non-destructive methods are used as accurate tools to evaluate and monitor asphalt mixtures. Among these methods, ultrasonic waves have been proposed as a widely used technique to evaluate the properties of asphalt mixtures. The use of ultrasonic waves has several significant advantages in the asphalt pavement evaluation process, including measuring voids and density, determining mechanical properties, and examining durability. By increasing the amount of air voids in asphalt mixtures, the speed of ultrasonic waves will decrease. In addition, ultrasonic waves make it possible to determine different mechanical properties of asphalt mixtures. To better understand the mechanical behavior of asphalt mixtures, researchers have proposed various mathematical relationships. These relationships establish connections between different moduli, including dynamic and Young's moduli, which act as basic mechanical properties of asphalt mixtures, and variables related to ultrasonic waves. Also, the speed of ultrasonic waves decreases when the asphalt mixtures are exposed to moisture damage. Therefore, with the increase in durability, the speed of ultrasound waves increases. In addition, changes in the amount of bitumen in the asphalt mixture have a significant effect on the speed of ultrasonic waves. Changes in the amount of bitumen affect the stiffness and density of the asphalt mixture and subsequently change the characteristics of the propagation of ultrasonic waves. By studying these effects, engineers can deepen their understanding of the relationship between bitumen content and mixture properties and develop relationships governing these phenomena and the optimal asphalt mixture. This research focuses on the application of ultrasonic methods to evaluate the properties of asphalt mixtures. The aim of this research is to investigate the relationships between these properties and variables related to ultrasonic waves, such as wave speed and propagation time, and to contribute to the advancement of the understanding of asphalt mixture behavior and the development of more effective and sustainable road construction.