Evaluation of morphological characteristics of fine aggregate in asphalt pavement

Aggregate makes up a high mass fraction in asphalt pavements. The morphological characteristics of aggregate (i.e., shape factors, angularity, and surface texture) significantly affect the mechanical performance of asphalt pavement. Extensive investigations of aggregate morphology have been conducted on coarse aggregate in recent years; however the analysis of fine aggregate has not been carried out up to date. Commonly used methods to extrapolate information on the morphology of fine aggregate such as sand flow test (SFT) and Uncompacted Void Content Test (UVCT) give a general characterization of the aggregate morphology without allowing for differentiated conclusions regarding the respective morphological factors. In this study digital image processing (DIP) is used to determine morphological index values of fine aggregate. Data from DIP is compared with results from UVCT and SFT by means of correlation analyses to investigate the applicability and precision of the respective methods. UVCT and SFT are found to be strongly reliable on the absolute grain size rendering the methods less resilient. DIP is very well suited to determine specific morphological indices of fine aggregates and is a useful tool for the design of asphalt mixtures.