An Image-based method for evaluating changes in particle size and morphology distributions of aggregate materials after vibratory compaction test

Particle breakage and abrasion of aggregate materials can be induced by field compaction during construction, which adversely affects their mechanical properties. However, current compaction quality control testing does not evaluate changes in particle size distribution and particle morphology of aggregate materials due to the lack of fast and inexpensive testing methods. In this study, a modified watershed-based segmentation image analysis method and computational geometry algorithms were used to quickly quantify changes in particle size and morphology distributions of a large amount of contacting aggregate particles. The accuracy and required minimum sample size of the image analysis method were statistically evaluated. Compared to the conventional ASTM C136 aggregate sieve analysis test, the image analysis method conducted on a 40% sample size of the conventional method yielded less than 6% difference between the results, which can meet the ASTM C136 test repeatability criteria. In addition, demonstration tests were conducted to incorporate the image analysis method into a laboratory vibratory compaction test for evaluating the overall particle size and morphology changes of an aggregate material after compaction. Results indicate that the initial gradation and water content of the aggregate material can influence the particle breakage and abrasion characteristics of aggregate materials under compaction.