Packing density of bi-disperse mixtures under one-dimensional compression

Giulia Guida,Francesca Casini,M.A Aguirre,R Soto,L.A Pugnaloni,S Luding

doi:10.1051/epjconf/202124907012

Giulia Guida, Francesca Casini + Show 4 more

Open Access

https://doi.org/10.1051/epjconf/202124907012

Copy DOI

Abstract

This work aims to investigate the effect of fines in different type of bi-disperse grain size distributions in terms of minimum/maximum density, compressibility and crushing. The material adopted is the Light Expanded Clay Aggregate (LECA), an artificial granular material characterized by light, porous and crushable grains. The bi-disperse grading are firstly analysed in terms of packing density, measuring experimentally the minimum and the maximum porosity for different combination of sizes and volume proportions. Then, some selected mixtures are subjected to one-dimensional compression tests up to high pressures. Evolution of grain size due to grain crushing phenomena and compressibility are therefore measured and interpreted. Finally a theoretical model is adopted in order to predict the mechanical material response accounting grain crushing and granular microstructure.

Highlights

The state of density of a granular material rules its mechanical, thermal and hydraulic behaviour
The bi-disperse grading are firstly analysed in terms of packing density, measuring experimentally the minimum and the maximum porosity for different combination of sizes and volume proportions
Some selected mixtures are subjected to one-dimensional compression tests up to high pressures

Summary

Introduction

The state of density of a granular material rules its mechanical, thermal and hydraulic behaviour. The greater is the range of grain sizes, the greater will be the density and the lower the minimum and maximum porosity [3, 4]. The more irregular is the shape of the grains the lower will be the density of the material, because irregularities hinders particle mobility and rearrangements [5, 6]. From a theoretical point of view [7], the variation of the state of density is mainly due to irreversible phenomena such as: rearrangement/dilation inducing a decrease/increase of the material porosity [8]; grain crushing [9] that, increasing the polydispersity of the grain size distribution, may lead to a decrease of the porosity maximum and minimum intrinsic limits. The effects of the percentage of fines and of the ratio between the coarse and the fine particles are explored, as well as the behaviour of some selected mixtures subjected to one-dimensional compression and grain crushing

Objectives

Findings

Conclusion