Sensitivity of HMA Performance to Aggregate Shape Measured Using Conventional and Image Analysis Methods

ABSTRACT There is a consensus among researchers and practitioners that aggregate shape properties affect performance, but a debate has arisen over the ability of the current tests to quantify these properties. Image analysis techniques have been shown in recent studies to be rapid and provide detailed information on the different shape properties. However, there is a need to compare the results from the image analysis methods with those from conventional tests based on HMA performance. The focus of this study is on the evaluation of the sensitivity of HMA performance to aggregate properties measured using conventional and image analysis methods. Wavelet image analysis is used to measure texture. Image analysis methods based on the changes in the gradient on a particle boundary, and the difference between a particle radius in a certain direction and that of an equivalent ellipse are used to quantify angularity. Form is quantified a method that evaluates the changes in particle radii with a fixed incremental change in the central angle. The performance of HMA mixes with different aggregates was measured using the asphalt pavement analyzer (APA), Hamburg wheel device (HW), and Dynamic modulus test (DM). In general, the results show that the image analysis methods used in this study had a better correlation with performance than the conventional methods.