Investigation of morphological effects on crushing characteristics of calcareous sand particle by 3D image analysis with spherical harmonics

Morphological effects on crushing characteristics of single calcareous sand particle were investigated experimentally. Before test, 3D images of 287 bulky particles with size range of 2.5–5.5 mm were captured using computed tomography scan, and outer and inner morphologies (i.e., size, sphericity, angularity and intra-particle void ratio) were extracted by image analysis with spherical harmonics. Then, uniaxial compression test was performed on individual particle to attain crushing characteristics (i.e., crushing strength, displacement, mode and fragment distribution). Normalized crushing displacement is found insensitive to particle morphologies. Crushing strength is positively correlated to sphericity, and negatively correlated to angularity and intra-particle void ratio. Particularly, crushing strength with intra-particle void ratio >4% is almost half of that lower than 4%. Fragments exhibits a mixed size distribution of large remnants and fines generated from contact damage and fracture plane. All test data can move towards a morphology-related upscaling model for calcareous sand crushing.