Gravel road embankments in low-lying areas. Cellular confinement systems can be used to prevent the washboarding effect. The gravel used consists of varying amount of crushed stone, sand, and "fines". Fines are silt or clay particles smaller than , which can act as a binder. Crushed stone is used because gravel with fractured faces will stay in place better than rounded river pebbles. A good gravel for a gravel road will have a higher percentage of fines than gravel used as a subbase for a paved road. This often causes problems if a gravel road is paved without adding sand and gravel
Granular material by vaulting and arching. If the granular material is driven harder such that contacts between the grains become highly infrequent, the material enters a gaseous state. Correspondingly, one can define a granular temperature equal to the root mean square of grain velocity fluctuations that is analogous to thermodynamic temperature. Unlike conventional gases, granular materials will tend to cluster and clump due to the dissipative nature of the collisions between grains. This clustering has some interesting consequences. For example, if a partially partitioned box of granular materials is vigorously shaken then grains will over time tend to collect in one of