Jämförande provning – ballast 2015: flisighetsindex, korndensitet och kulkvarn

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This report shows results, some statistical analysis and precision data for profiency testing (round-robin) performed on three materials of aggregate during 2015. The properties that was determined was Flakiness Index (EN 933-3), particle density (EN 1097-6) and Nordic ball mill (EN 1097-9). The number of participating laboratories were for Flakiness index 58 pcs., for particle density 60 pcs. and for Nordic ball mill 52 pcs.

There are some scatter of the results which is not surprising. A few of the laboratories show clearly high or low results (for all three materials) for one of the analysis. Generally is the scatter in results varying. E.g. some of the laboratories have a clearly high result for one of the materials, a slightly low result for the second material and are quite close to the average for the third material.

The standard deviations increase with increase in level of results (average), but not as much. The ratio of standard deviation and average decrease with increase of level.

The precision data from this round-robin over all matches the levels from the test standards. The tests from this report has often a wider range of results. There is a correlation between reproducibility and level of average. The repeatability has not been calculated because tests actually have been performed as single tests.

Analysis of background data, like handling, dimensions and type of model, shows that they have none or very little significance.

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