Volume 80, Number 3, November 2007
Article Number 38002
Number of page(s) 5
Section Interdisciplinary Physics and Related Areas of Science and Technology
Published online 02 October 2007
EPL, 80 (2007) 38002
DOI: 10.1209/0295-5075/80/38002

The shear modulus of wet granular matter

P. C. F. Møller1 and D. Bonn1, 2

1  Ecole Normale Supérieure, Laboratoire de Physique Statistique - Paris, F-75231 France
2  van der Waals-Zeeman Institute - 1018 XE Amsterdam, The Netherlands

received 21 May 2007; accepted in final form 9 September 2007; published November 2007
published online 2 October 2007

The strength of different wet granular materials is investigated as a function of the liquid volume fraction by measuring the elastic shear modulus, $G ^\prime $. We show that the optimum strength is achieved at a very low liquid volume fraction of 1-3%. Surprisingly we find that the macroscopic strength of different wet granular materials depends with a power of 2/3 on the microscopic elastic modulus of the individual grains, with a power of -1/3 on the radius, and with a power of 1/3 on the surface tension. This can be explained by assuming that the attractive capillary force between two grains deforms the grains elastically, yielding a "spring constant" for further deformation. Averaging over many grain-grain orientations allows us to predict the macroscopic shear modulus in excellent agreement with our experiments.

83.80.Fg - Granular solids.

© Europhysics Letters Association 2007