Sand for sports surfaces: choose the ideal one

Sands are minerals with a grain size between approximately 0.05 mm and 2.0 mm. They can be of siliceous nature with rounded grains, calcareous with more angular grains, feldspathic, etc.

The use of calcareous sands is not recommended due to their basic reaction and high buffering power, which leads to their physical and chemical wear and the impossibility of lowering the pH. 

The most important characteristic for the rooting zones is the high porosity of the substrates, although agronomically they are not very fertile. In the case of bunker sands, compressive strength is sought, determined by penetrometer with ranges between 2.4 kg/cm2 for high strength and 1.8 kg/cm2 for low strength.

The distinction between one size and another is measured through the value of the DxThe size in micrometres of the sieve through which x % of particles pass. Thus D10 represents the sieve through which 10% of the smallest particles pass, D50 the sieve through which we separate half of the particle size or D90, which informs us of the largest particle size. Uniformity will be given by the D90/D10 ratio, the lower the ratio, the more uniform.

On football pitches, sands with D50=230 micrometres are recommended, and on greens with D50=330 micrometres. In both cases, uniformity values of less than 3.3 are recommended.

Thus, the different aggregates have characteristic particle size curves. The particle diameter is represented on a logarithmic scale (abscissa), and the percentage of material passing is represented on an arithmetic scale (ordinate).