Investigation of the fracture behaviour of individual LBS particle using Nanofocus X-ray CT

Particle breakage is of fundamental importance to understand the mechanical behaviour of sands and is related to many geotechnical-engineering problems. Generally speaking, breakage is a macroscale description of the micro-scale fracture or fragmentation of many individual particles. Despite considerable research dedicated to the micromechanics of sand associated with particle breakage, the fracture process of natural sand particles is not well understood. In this paper, we combine X-ray computed tomography (CT) with in-situ experiments to investigate the failure mechanism of individual sand particles. A mini-loading apparatus which is suitable for examining the initiation and propagation of microcracks in a single sand particle with nanofocus X-ray CT (μCT) is developed. Preliminary results have been obtained from the in-situ scanning of the fracturing processes of Leighton Buzzard sand (LBS) particles. The μCT images are processed using a 3D median filter and thresholding segmentation to reduce the noise and separate the regions of interests. The fracture patterns of these particles are presented and discussed through the CT images taken at the three states. The spatial distribution of the fractures is complex and different kinds of fracture mechanics could be observed. It is shown that the fracture behaviour of these two particles is mainly influenced by the loading conditions and their morphology. © 2015 Taylor & Francis Group.