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UP: Umweltphysik

UP 3: Boden- und Agrarphysik

UP 3.1: Fachvortrag

Montag, 13. März 2006, 14:30–14:45, E

Rheometry: A method to detect inter-particle effects in soils — •Wibke Markgraf and Rainer Horn — Institute for Plant Nutrition and Soil Science, Christian-Albrechts-University of Kiel, Hermann-Rodewald-Str. 2, D-24118 Kiel

Rheometry is a method that is commonly applied in food industries, polymer research, or sectors that are related to clay mineralogical issues, to investigate flow behaviour of viscous, elastic or viscoelastic substances. In soil mechanics shear behaviour is one of the major objectives, as trafficking and different tillage systems affect structural stability in dependency on the water content, texture and other physicochemical properties of a soil. Direct shear, oedometer or triaxial tests are executed on undisturbed samples to achieve data about pre-compression and the angle of friction on a meso-/macro-scale. Due to conducting oscillatory tests under controlled shear deformation (CSD) on a rotational rheometer with a parallel plate measuring system on several homogenised, clay and silt-rich substrates, it is possible to detect inter-particle effects between single grains and/or platelets. Variations in water content, texture, salt contents and types of salt (valency effects) lead to new perceptions. On the basis of the linear viscoelastic (LVE) deformation range, including a deformation limit γL, which both derive from the storage and the loss modulus, mechanical behaviour on a micro-scale can be quantified.