|Abstract:||This study focused on evaluating performances of different video imaging systems, both commercially available and newly developed, for automating the determination of coarse aggregate (nominal size greater than 4.75 mm or No. 4 sieve) size and shape properties, i.e., flat and elongated ration, gradation, and angularity. These properties impacting performance of asphalt pavements were previously developed into a set of consensus properties to identify proper aggregates for SHRP Superpave asphalt concrete mix designs. A total of 10 bags of aggregate samples, primarily crushed gravel, limestone, and dolomite provided by the Illinois Department of Transportation (IDOT), were used to evaluate speed, precision, and accuracy of various image analysis techniques, specifically, (1) the digital image analysis technique proposed by Frost and Lai (1996); (2) the commercially available French video grader VDG 40; (3) the recent WipShape system at the University of Missouri-Rolla; and finally, (4) the new "University of Illinois (UI) Aggregate Image Analyzer." Based on the evaluation results, not all the properties, i.e., flat and elongated ration, gradation, and angularity, could possibly be determined from one system. The new UI Aggregate Image Analyzer was developed to provide one system for all properties, based on the use of 3 cameras for accurately reconstructing the three-dimensional shape, i.e., computing volume of an aggregate particle, and automating the determination of all the aforementioned properties. The Analyzer took approximately 70 minutes to test an entire bag of over 1000 particles using a Pentium II computer with a 350-MHZ processor speed. The computed flat and elongated ratios in percentage by weight were in very good agreement with the results obtained by manual caliper at IDOT. The repeatability of the UI Image Analyzer results was also very good. The imaging based gradation curves were found to match very closely with the mechanical sieve analysis results. In addition, a new Angularity Index was developed to numerically quantify the shape of coarse aggregates analyzed using the UI Aggregate Image Analyzer.