Tensile strength of cohesive powders

Journal article (2019)

Authors

Pablo García-Triñanes University of Greenwich
Stefan Luding University of Twente
H. Shi University of Twente
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Tensile strength Limestone Cohesion Brookfield powder flow tester Schulze ring shear tester Shear index Warren Spring model
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Published Date

2019

Language

English

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Abstract

Measurement and prediction of cohesive powder behaviour related to flowability, flooding or arching in silos is found to be very challenging. Previous round robin [52] attempts with ring shear testers did not furnish reliable data and have shown considerable degrees of scatter and uncertainty in key measurements. Thus studies to build a reliable experimental database using reference materials are needed in order to evaluate the repeatability and effectiveness of shear testers and the adopted procedures. In this paper, we study the effect of particle size on the yield locus for different grades of limestone (calcium carbonate). We use the nonlinear Warren Spring equation to obtain the values of cohesion C, tensile strength T, and the shear index n. We recover linear (n = 1) yield loci for d50>70 μm with respectively small C and T, with consistent, finite macroscopic friction C/T = 0.7. With particle size decreasing below 70 μm the response becomes more and more cohesive and non-linear (1