Multi-Morphological Characteristics of a Crushed Granitic Rock of Varying Sizes

Abstract

Crushed rock fragments are usually a mixture of particles with different sizes and morphologies comprising particle shape and surface texture scales. The significant role of particle morphology in the engineering behavior of granular materials has been increasingly appreciated. However, studies on morphology are mainly on particles of similar sizes, and the few studies that reported particles with varying sizes are limited to particle shape scale alone, especially when 3D morphological characteristics are considered. In this paper, we investigate the multi-scale morphological characteristics of crushed rock with a size ranging from sand to gravel by employing a 3D laser scanner and micro-Computed Tomography (μCT) using quantifiers of sphericity, aspect ratio, and roundness for particle shape, and fractal dimension for surface texture. Crushed granitic rock is used as the testing material to elucidate the morphological characteristics of crushed materials, which are not uncommon in geotechnical applications. For the tested crushed granitic rock, as particle size decreases, the overall shape becomes slightly angular, the corner of the particle becomes more rounded, and the surface becomes smoother. Differences in the morphological descriptors for small particles, mainly those with singular mineral composition, have also been observed and might be explained in terms of hardness and fracture features. The observed dependence of morphological descriptors on particle size and mineralogy bears significance for investigations using reconstructed particles of different sizes using 3D-printing techniques and numerical methods.