The method can be applied to a wide range of materials originating mainly from the tilled horizons of cultivated soils. It can, however, also apply to any soil profile horizon, whether it is cultivated or not. Aggregates ranging from 3 mm to 5 mm are measured. However, the presence of gravel in the 2 mm - 5 mm fraction can distort the results. If the percentage of gravel is between 10% and 40%, the > 2 mm fraction of the gravel obtained from the tests should be washed and a mean weighted diameter (MWD, see 5.5) calculated with and without gravel. If the percentage of gravel is > 40%, the structural stability tests will not be significant. The method does not apply to unstructured materials, as they are not sufficiently cohesive to form millimetric aggregates.