Grain structure

A grain framework is a space lattice of connections at the points of contact of grains e.g. B. in sand , gravel or grit .

The best way to explain it is this: Instead of grains of sand, you can imagine tennis balls in a round glass cylinder. The points of contact between the balls form the grain structure.

The stability of the grain structure depends above all on the density , i.e. on the utilization of the cavities (pore spaces) between the tennis balls. If you press on the balls from above, they will be relatively easy to compress. But if you add table tennis balls to the tennis balls, mix them well (one also speaks of compacting) and press again from on top, the balls are much more difficult to compress. The reason for this is that the table tennis balls sit in the cavities between the tennis balls, thus taking up the space to be pressed together and thereby providing more stability.

You can think about this further and add different sized grains or balls, whereby the cavities are further filled and the grain structure is further stiffened and thus more stable. The better the cavities are used, the more stable a grain structure is.