Characterization of sand particle morphology: state-of-the-art

The morphology of granular materials, such as sands, is of significant importance due to the effect of grain shape on their physical, mechanical, and hydraulic behavior. As technology has progressed from visual identification to modern computer-based techniques, numerous methods have been developed for quantifying grain shapes, many of which utilize digital image analysis and advances in computational techniques. A comprehensive understanding of available shape characterization methods is essential to make better use of these tools. This paper presents a state-of-the-art review of current methods for characterizing the morphology of granular materials, focusing particularly on digital image analysis techniques. It critically evaluates two essential aspects of shape characterization: the acquisition of particle shape information and shape measurement methods, discussing the strengths and limitations of each approach. Further, the application of grain shape characterization to analyze the effect of particle shape on the macro-scale behavior of sand is discussed. The review emphasizes the need to shift from classical shape characterizations developed by sedimentologists to objective-oriented shape characterizations that enable micro-to-macro correlations, taking into account the availability of robust tools and technologies.