The aggregate is made up of a set of mineral grains which, depending on their size, fall into one of 7 families (sand, gravel, ballast, etc.). Their nature, shape and characteristics vary depending on the deposits and production techniques.
The mineral nature of the aggregates is a fundamental criterion for their use, each rock having specific intrinsic characteristics in terms of mechanical resistance and frost resistance, as well as physicochemical properties and chemical properties.
Aggregates are classified according to their granularity (dimensional distribution of grains) determined by granulometric analysis using sieves.