Dresden 2011 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
CPP: Fachverband Chemische Physik und Polymerphysik
CPP 44: Micro- and Nanofluidics I
CPP 44.13: Vortrag
Donnerstag, 17. März 2011, 17:15–17:30, ZEU 160
Mechanical Properties of Wet Granulates — •Somnath Karmakar1, Marc Schaber1, Mario Scheel2, Marco Di Michiel2, Stephan Herminghaus3, and Ralf Seemann1,3 — 1Saarland University, Saarbrücken, Germany — 2ESRF, Grenoble, France — 3Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany
Adding small amounts of a wetting liquid to dry granular matter typically leads to a substantial increase of the mechanical stiffness of the granular media. This arises due to the formation of capillary bridges, exerting an attractive force between individual grains. We study the mechanical properties, i.e. yield stress, tensile strength and critical fluidization acceleration of wet granular materials with different wettability using glass and basalt beads and sand grains at various liquid contents. The mechanical properties are probed for various experimental conditions and surprisingly the wetting liquid might act as a lubricant for a granulate sheared at large absolute pressure. Moreover, we experimentally find for a wetting system a yield stress that is depending on the applied shear frequency. For a granular system with low wettability however, the yield stress is independent of the shear frequency. By time resolved X-ray tomography experiments we can explain this behavior by a liquid exchange process occurring between the individual liquid morphologies emerging in wettable granulates but which is not observed in granulates with low wettability.