N. Poplavska

**Summary**

Granulometric (grain) composition is the weight content of particles of different sizes, expressed as a percentage of the mass of the dry sample taken for analysis.

The weight ratio of the conventional size groups of mechanical elements (particles represented by mineral grains) of dry soil is called the mechanical (granulometric) composition of the soil, i.e. the ratio of fractions of physical clay (particles less than 0.1 mm) and physical sand (particles larger than 0.1 mm).

By means of granulometric composition analysis, the quantitative ratio of structural elements of solid components of different sizes is estimated.

According to its results, the dispersion of the soil is considered, as well as its classification.

There are different methods for determining the granulometric composition (sieve, pipette, aerometric), which are widely used in soil science research and have common and inherent errors, such as the error in particle weighing, oscillation, soil particle density, temperature change, viscosity and density of the suspension etc .

The classic method of granulometric analysis of sand fractions (sand) is based on sieve analysis. The research is carried out using a set of sieves with different holes’ diameters, each size fraction is weighed on the scales and the results are converted to the percentage of each fraction of a certain size.

When carrying out examinations of the comparative research of sand, the laser diffraction analyzer «Mastersizer 3000» is used to determine the quantitative content of the granulometric composition.