For powders consolidated under non-steady state, the stress history will influence the obtained failure strength in a shear tester. We have been looking at different filling procedures for the Uniaxial tester, developed by Tel-tek dept POSTEC, and the influence of flow properties for BCR limestone and industrial cement. The influence of using vibration feeder, vibration table, vacuum and a pin for packing the powder sample are investigated. The procedure during filling seems to have an influence on the measured failure strength and the reproducibility of the tests. Experimental design and multivariate data analysis are used to plan the tests and analyze the results, to obtain as much reliable information as possible from the experiments.

The Uniaxial tester is an indirect shear tester, where the compressive failure strength can be determined directly as a function of the previous consolidation. The powder sample is uniaxially consolidated in a die by pressing down a piston. The boundary between the sample and the die is made nearly frictionless by means of a lubricated flexible rubber membrane. After consolidation to a predesided consolidation stress, the axial stress as well as the die are removed. Then the unconfined sample is loaded again until it fails and the compressive strength is measured.