An evaluation method of aggregate morphological characteristics based on two-dimensional digital image technique

Aggregate shape, angularity and surface texture are closely related to pavement performance of asphalt mixture. In order to quantitatively analyze the morphological characteristics of aggregates, the aggregate particle image was obtained by "backlight scanning method", and then noise removal, segmentation and hole filling are performed on the acquired image based on digital image processing technique. On the basis of above mentioned, a two-dimensional aggregate morphological characteristics evaluation system (AMCES) with low equipment requirements was developed. The shape property of aggregates were characterized by shape index (SI) and form factor (FF), and the angularity property and surface texture of aggregates were evaluated by angularity index (AI) and texture factor (TF) respectively. Finally, the morphological characteristics of 12 different standard shaped objects and limestone with 4 different sizes were analyzed. The test results show that the four evaluation parameters can describe the morphological characteristics of aggregate particles well. With the increase of particle size, the shape index decreases, the value of the form factor get closer and closer to 1, while the angularity index and texture factor both decrease gradually.