Spermatozoon

The granulometry is the study of the distribution of the elements according to their size, in the case of a material split.

Determination of granulometry

The method of determination of the simplest granulometry is obtained by passage through a series of Tamis of decreasing meshs. For the finest elements (less than 80 µm), one proceeds by Sédimentométrie.

For fine powders, one can use a laser particle-measurement instrument : the powder is convoyed by water or air and passes in a beam Laser. The laser diffracts on the particles; the width of the Tache of Airy makes it possible to determine the size of the grains.

It is necessary to distinguish granulometry from the size of the Cristallite S, such as that obtained in Diffraction of x-rays (for example by the method of Scherrer): a grain can be made up of several crystallites.

In Geology

This granulometric analysis makes it possible to define various material classes independently of their chemical nature. The table below corresponds to French standard NF P18-560 used in particular in the road field.

Here 3 other usual classifications:

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Other definitions also result from this, for example that of the coarse-grained soils which comprise more than 50% of elements of granulometry higher than 80 µm. They are divided then into two families:

  • serious so more than 50% of the elements > 80 µm has a diameter > 2 mm
  • sands so more than 50% of the elements > 80 µm have a diameter < 2 mm

See too

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