Transparent confined compression tests on particle beds: Observations and implications

Particle breakage is quite common in a variety of engineering circumstances, and the underlying mechanism as well as its effects on overall responses of particle assembly still demand further investigation mainly due to the difficulty in monitoring the progressive size reduction process. This paper presents a series of confined compression tests for two kinds of quasi-brittle spherical particles, namely Al2O3 and ceramic granules. A broad range of particle sizes and feed gradations were considered, and a transparent sample container was purposely adopted for a direct observation of particle disintegration. Typical macro- and micro-scale test results are presented, including the development of overall load-bearing capacities versus the compaction displacement, disintegration modes of single particles as well as the description of fragment size distributions. Two characteristic indexes t(sqrt) and B-r' are proposed to quantify the fragment size distribution and particle breakage degree, respectively. It is also found that under the same specific input energy, distributions of fine products from samples of different feed gradations remain basically the same. The findings facilitate a better understanding of the macro- and micro-scale progressive particle breakage behaviour under one-dimensional compression, and some concluding remarks are provided in the final part of the paper. (C) 2018 Elsevier B.V. All rights reserved.