Analysis by x-ray microtomography of a granular packing undergoing compaction

TL;DR

This study uses X-ray microtomography to analyze how a granular packing densifies under vibrations, revealing pore size distribution changes consistent with free volume theory and previous models.

Contribution

It provides experimental evidence of pore evolution during granular compaction, validating numerical models with real microtomography data.

Findings

Pore volume distribution has a large tail compatible with exponential law.

Large pores decrease as the system becomes more compact.

Results align with free volume theory and previous numerical models.

Abstract

Several acquisitions of X-ray microtomography have been performed on a beads packing while it compacts under vertical vibrations. An image analysis allows to study the evolution of the packing structure during its progressive densification. In particular, the volume distribution of the pores reveals a large tail, compatible to an exponential law, which slowly reduces as the system gets more compact. This is quite consistent, for large pores, with the free volume theory. These results are also in very good agreement with those obtained by a previous numerical model of granular compaction.