MECHANICAL-PROPERTIES OF COHESIVE PARTICULATE SOLIDS

Measurements are reported of the effective elastic modulus and failure under load of compacts formed from two sizes of glass ballotini. In some measurements, the particles were treated to render their surfaces hydrophobic and therefore less sensitive to contamination or humidity. The adhesion energy between treated and untreated glass surfaces was also measured directly. The compacts behaved as elastic bodies over limited ranges of strain, but the effective elastic modulus differed according to the method of loading. Qualitatively, failure of the compacts occurs by a process typical of brittle/elastoplastic materials. The measured elastic moduli and fracture energies were not consistent with theoretical models based on summing the interaction forces and energies between particles in the compact, and possible reasons are discussed.