Experimental study on the dependence of the stability of binary mixtures on the coordination number

Abstract

We report the effects of interstitial matter of different sizes on the angle of repose, Θ_Rand on stability of granular heaps in 3D. For all the heaps where the size of the interstitial matter is small enough to fill the voids between the grains, more contact points are incorporated. This caused an increase in Θ_R up to a maximum greater than the limit values (Θ_R of pure mixture components), implying greater stability. On the other hand, when the size of the interstitial matter approaches the size of the grains, Θ_R varies negligibly and linearly between the two limit values. It was further verified using a 2D experimental setup that relatively smaller disks tend to increase the average coordination number <z> of a binary mixture of disks. Thus, the effective behavior of dry granular materials, for these experiments is subject to the size of an interstitial matter when present.