Air Void Distribution of Asphalts Determined by Computed Tomography

Abstract

Durability and functionality of hot mix asphalts (HMA) depend on air voids and their characteristics. The air void content of asphalt core samples could be determined by direct and indirect methods. The direct methods are destructive since they determine the air void content by decomposing the mix into its individual components. They are usually accurate but time consuming and use hazardous solvents. Because of the environmental hazards and restrictions associated with the solvents other analysis methods become really important. The computed X-ray tomography (CT) makes it possible to create a complete 3D image about the whole inner structure without any preparation or chemical fixation of the specimen. This nondestructive structure testing has a great significance at the examination of road pavement structures and could substitute a number of complex laboratory test in a more accurate and robust way. This paper demonstrates the CT method for determining the air void distribution. It shows that the proposed method can determine the air void content very accurately and gives a lot of additional information about other features by showing the distribution of the air void content along any arbitrary axis of the core sample.