An investigation of breakage behaviour of single sand particles using a high-speed microscope camera

Much research has focused on the micro-mechanics of sand particles. The single particle uniaxial compression test is a common way to study breakage behaviour. However, there is still little agreement on particle breakage criteria and the mechanisms of breakage remain uncertain, partly because of the often rapid brittle failure of sand particles. In this study, a series of single particle uniaxial compression tests on different kinds of sand particles were carried out, using a high-speed microscope camera to capture the processes of breakage. This enabled a maximum of 2000 frames to be obtained per second to identify clearly the failure processes and crack propagation. Four failure modes have been proposed based on the rapidity of failure and the size and number of particle fragments created during the breakage: splitting, explosive, explosive–splitting and chipping. The relationship between the particle strength and the breakage mode has then been explored, investigating also whether immersion would affect the breakage mode and strength. The morphologies of the sand particles including local roundness, particle size, aspect ratio, regularity and two-dimensional sphericity were measured to investigate their influence. With assistance of the high-speed microscope camera, the crack initiation locations were identified and the frequency of different locations obtained, comparing the results with existing particle micro-mechanical theories.