Validation Of Shear Testing Using The FT4 Powder Rheometer And Limestone Powder CRM 116

Summary

This study validates shear tests carried out using the FT4 Powder Rheometer on a standard CRM 116 limestone powder. Yield loci were derived at each of the four pre-shear normal stresses as laid down in the standard. The results are shown to be within 5% of the standard and well within its uncertainty tolerance.

Shear Testing

The original function of shear testing was to provide input data in the design of silos for the reliable (i.e. mass flow) discharge of powders and bulk solids. The data obtained through shear testing can be used to determine the opening size required to prevent arching and rat-holing in a bin or hopper. The shear test can also be utilised to evaluate the affect of numerous environmental conditions on material flowability. One key factor is the affect of storage time on the flow properties of the bulk material when it is subsequently required to flow.

The FT4 Powder Rheometer provides dynamic flow properties for powders, which can be used to aid process and formulation engineers in the optimisation of process plant that will effectively and consistently achieve the final product. Complimentary to these dynamic flow measurements, the shear cell accessory allows the FT4 to make precise and rapid shear measurements. This data including cohesivity values can be related to the dynamic flow properties and also utilised for silo and hopper design.