Attempt at Quantifying the Degree of Compaction in HMA Using Image Analysis

In this study, an attempt was made to estimate the degree of compaction using specific parameters derived from two-dimensional image analysis of cut-sections of HMA specimens. This was done by studying the inter-particle distances in HMA specimens compacted using a Linear Kneading Compactor (LKC) at different air voids. The imaging parameters were based on nearest neighbor distance methods such as Delaunay triangulation and Voronoi tessellation schemes. A program was developed using an image processing software to analyze the changes in the coarse aggregate distribution and orientation during compaction. In the second part of the study, a two-dimensional cross-section of HMA was simulated in computer using the mixture design information. At the end of each simulation, all the parameters were measured and the results were compared with the results from image analysis. The results of the study indicated that the changes in inter-particle distances during compaction could be measured using two-dimensional image analysis of a sawed section of a sample. The study of the inter-particle distances would enable determination of compaction in different directions and comparison between different compaction techniques. Developing such a technique would help determine if a specimen is compacted to different degrees at different locations of the pavement and help in decreasing the differences between laboratory and field compaction techniques.