Round robin test on ring shear testers

In 2008 a round robin project on ring shear testers was initiated in order to determine a range of results for a defined bulk solid (limestone powder CRM-116), similar to a round robin project with Jenike shear testers carried out in the 1980s. All users of automatic ring shear testers RST-XS or RST-01.pc were invited to take part. Twenty-seven labs supplied results. Finally, per stress level up to 60 yield loci (21 labs) measured with the RST-XS, and up to 19 yield loci (10 labs) measured with the RST-01.pc have been received.Compared to the above mentioned tests on Jenike-type shear testers, both ring shear testers provide clearly smaller standard deviations. Thus, despite different ambient conditions, the range of results is quite narrow.With the mean values and standard deviations calculated from the ring shear tester results a kind of “reference range” is defined. This range should be matched with a certain probability with the results of future tests with the standard powder if the instructions regarding stresses and ambient conditions are followed. Thus, the results provide orientation to all users of ring shear testers RST-XS and RST-01.pc.