Quantifying the morphology of crushed sand particles using X-ray micro-tomography

Particle breakage plays a crucial role in determining the macroscopic mechanical behaviors of granular materials, such as compressibility and shear strength. This study aims to investigate the mechanical behavior and particle shape evolutions of three types of granular materials, namely Leighton Buzzard sand (LBS), glass bead (GB), and carbonate sands (CSs), through a series of 1D compression tests. The study employs micro-computed tomography (micro-CT), image processing, and analysis techniques to build a comprehensive fragmentation database and elucidate the statistical mechanical behavior of granular materials. A set of samples were prepared for each granular material type and compressed to a desired stress level. The compressed samples and natural sand particles were then scanned using micro-CT, and the irregular particle morphologies were reconstructed through a series of image processing techniques. By analyzing the particle size distributions and the evolutions of the particle shape, a detailed comparison between the LBS, GB, and CS particles was conducted. The study reveals that the mechanical behavior and fracture patterns of granular materials are influenced by the initial particle morphology and mineralogy. The CS particles, which exhibit abundant intra-particle pores and irregular morphology, have lower compressive strength and higher compressibility compared to LBS and GB particles. Furthermore, the study finds that the particle size of the newly generated fragments for LBS, GB, and CS particles is primarily concentrated around 0.3 mm, 0.65 mm, and 0.18 mm, respectively, indicating significant differences in the particle failure modes between them. The statistical analysis of the newly generated fragments provides quantitative results that help us better understand the development of particle breakage and gain deep insights into the role of grain shape in the mechanical behavior of granular materials. Graphical abstract