Rheological behavior of fine and large particle suspensions

A new rheometric system, the ball measuring system, is used to determine the rheological behavior of fluids with large particles. To assess the applicability of the new system for debris flow material, artificial fine particle suspensions are investigated with the ball measuring system and a conventional concentric cylinder system. The agreement between the flow curves obtained by both systems is good. In a second step, defined amounts of coarser grains are added stepwise to the fine particle suspension to obtain different large particle suspensions. There is an increase in data scattering with an increase in large particle concentration. Thus, the question is raised for which grain size distribution, sediment concentration, and which process the traditional rheological approach is still appropriate when describing the flow process of debris flow mixtures. The curve fitting for the different fine and large particle suspensions is described using the Herschel-Bulkley model. Finally, the range of application for the ball measuring system is discussed. Today it is a suitable new rheometric system for fluids with particle sizes up to 10 mm and for measurements in the laminar flow field. The application for this system could potentially be expanded, for example, to measure fluids with particles sizes up to 200 mm with a large scale device.