Sand grains versus tiny glass granules - comparative study on stress-deformation characteristics

Glass granules and grains of crushed glass usually replace sand if photo-elastic observation of load-transmitting ‘force chains’ is planned. Still an open question exists however, how well glass granules can represent real sand grains. This paper in its first part compares simple uniaxial crushing tests on glass grains (both granules and crushed glass) and on coarse sand grains (micro-scale). Some basic geometrical characteristics of glass and sand grains are discussed, then the measurement techniques are presented and the results of crushing tests demonstrated. The second part of the paper contains the results of ‘macro-scale’ loading tests on big granular samples, made of ~106 glass or sand grains. The deformation characteristics of these samples differ significantly.