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Partic. vol. 46 pp. 1-13 (October 2019)
doi: 10.1016/j.partic.2018.09.010

The influence of particle characteristics on the index void ratios in granular materials

Debdeep Sarkar*, Diethard König, Meisam Goudarzy

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debdeep.sarkar@rub.de

Highlights

    • A model to predict maximum and minimum void ratios for granular matter is presented. • The model is based on the particle shape represented through regularity factor computed using image analysis, and specific gravity. • Mean grain size best represents the extreme void ratios for poorly graded glass beads. • The uniformity coefficient is better suited for sands. • The specific gravity ratio, introduced herein, improved the accuracy of the extreme void ratios estimate.

Abstract

The goal of this paper is to assess the effects of particle and specific gravity characteristics (e.g. shape, size, and specific gravity) on the limiting void ratios emax and emin of granular matter. To assess the effect of specific gravity, two different types of materials—glass beads and natural sands—were used. Particle characteristics such as roundness (R), sphericity (S) regularity (ρ), the average of R and S, were calculated through image analysis techniques after obtaining high-quality microscope images of individual grains. The German DIN standards were strictly followed to determine the extremities of the void ratio. Experimental data were used to investigate the effects of the particle characteristics on the relative density of soils. The results show the significant effect of the mean grain size (D50) on the extreme void ratios of poorly graded glass as well as the significant effect of Cu but negligible effect of D50 on the extreme void ratios of sand. The effect of the specific gravity of the materials was also examined. The results were used to develop models dependent on both particle shape and specific gravity, which were validated by comparison with results of previous studies.

Graphical abstract

Keywords

Void ratio; Particle shape; Specific gravity; Image analysis; Uniformity coefficient; Mean grain size