The Application of Digital Image Processing Technology in the Quantitative Study of the Coarse Aggregate Shape Characteristics

The angularity of coarse aggregate is a key characteristic. The high-temperature stability, low temperature anti-cracking performance and moisture susceptibility of asphalt mixture are influenced greatly when coarse aggregates are used in the asphalt pavement. Three indexes were used for quantizing the angularity of coarse aggregate. They are FI (Form Index), Angularity GM (Gradient Method) and Angularity RM (Radius Method). These three indexes can be obtained through computing the coordinates of the edge-points of the coarse aggregates. The coordinates can be obtained through image processing. The whole process is divided into the following steps: image preprocessing, image segmentation, morphological image processing and contour tracing. Automatic processing of data by computer greatly reduces the workload, and provides the convenience for calculation and storage of data. The information collection of the angularity of coarse aggregate is simplified.