The specific gravity of gravel depends strongly on the grain size

In order to organize the needs and above all the transport of gravel, the specific weight must be calculated. The density of each gravel indicates the weight of the rock including the weightless voids between the gravel for one cubic meter.

Density decreases with increasing grain size

Unlike calculating the specific gravity of sand, gravel increases the immutability of the weight with the size of the grains or pebbles. While fine gravel is still good to compact, this feature is reduced in mean gravel. For coarse gravel with stone sizes from twenty millimeters, the stones "fall" immediately into their final position to each other.

The specific gravity decreases with the grain size, because the spaces between the pebbles are increasingly compacted with increasing stone size by shaking or pounding. For sorts with a wide range of grain sizes, such as gravel mixtures from zero to 32 millimeters, the density that the smaller pebbles "trickle" into and close into the voids between the large stones increases. It creates a higher amount of stone or stone share in the same size.

Wetness is stronger with smaller grain size

The larger the grain size or the pebbles are sorted, the less influence the condition of the gravel exerts on the specific weight. While wet gravel grades can have up to 25 percent higher specific gravity than dry gravel for sorting with fine gravel, this makes up to five percent of rough gravel sorting.

The specific gravity is calculated from the density and depends on whether the prices are in tonnes or cubic meters. If the calculation unit is the cubic meter, the required room volume must be multiplied by the weight. If the weight is given in tons, the space requirement is divided by the density.

Density of classic gravel sortings

  • Concrete gravel (grain size 0-16 millimeters), 1.8 tons (t) per cubic meter (m³)
  • Rhine gills (16-32 mm), 1.7-1.75 t / m³
  • Rhine gills (32-100 mm), 1.6 t / m³
  • Gravel mixture (0-32 mm), 1.8 t / m³

The smaller the number of grain sizes in the sort, the greater the effect on the density. Example of gravel with zero to 32 millimeters.

  • Dry gravel 1.5 t / EUR
  • Earth Moisture Gravel 1.8 t / m²
  • Wet gravel 2.0 t / m³

Tips & Tricks

If you want to achieve a water infiltration and a drainage effect, use only gravel with the smallest grain size of two millimeters.

Video Board: Mod-01 Lec-10 Pores and porosity in concrete