Blending liquid into a flowing dry granular material

Guillaume Saingier,Pierre Jop,Alban Sauret,F Radjai,J.Y Delenne,S Luding,S Nezamabadi

doi:10.1051/epjconf/201714009011

Abstract

We study experimentally the growth dynamics of a horizontal wet granular aggregate produced by accretion when a dry granular jet impacts a wet substrate. The tomographic imaging demonstrates that the wet aggregate is fully saturated and its cohesion is related to the capillary suction due to the pressure drop at the liquid/air interface. We highlight that the accretion process is characterized by two different growth dynamics depending on the hydrostatic depression in the material. At low depression, the growth dynamics exibits a “diffusive” regime whereas the dynamics becomes linear for higher depressions. A competition between the viscous displacement of the fluid into the granular material and the sticking dynamics is proposed to understand the transition in the growth velocity.

Highlights

Granular materials are commonly used as raw materials in the building industry [1]
We proposed to study the internal structure of the wet aggregate and its growth dynamics
The blending of liquid into a dry granular flow is considered in a model situation to create a wet aggregate growing by granular accretion at the interface between dry and wet grains

Summary

Introduction

The preparation of many building materials such as concrete, mortar or plaster requires mixing granular matter with liquid and additives in order to obtain new chemical or physical properties. Spatial heterogeneities can appear during the blending process and generate bubbles or saturated aggregates, which will locally impact the mechanical properties of the final material. Most studies on wet granular matter are focused on the fluid flow dynamics and the repartition of the liquid into a static granular packing [5, 6]. In this case, the material can be assimilated to a porous medium. The liquid transport is essentially led by capillarity in the porosity of the material and exhibits well-known imbibition dynamics described in 1D by the Lucas-Washburn law [7]

Results

Discussion

Conclusion