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Lab test
Environmental labs

Flatness index

A determination of flatness index in accordance with NEN-EN 933-3 serves to determine the percentage of flat pieces in a stone mixture. Too much flat material can cause fractures in the foundation. The flatness index therefore says something about the strength of a foundation material.

Process

For this test, the grain distribution is first determined. Grain sizes of less than 4 mm or more than 80 mm are not included in the test. Bar sieves are then used to determine the flatness index. Pieces with a specific length-to-thickness ratio fall through these bar screens during this test. For each sieve component, the percentage of flat pieces can be determined. At the end of the test, the total percentage of flat pieces of the sample is calculated.

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