Function of the aggregates
In general, the function of aggregates is to reduce the shrinkage of concretes and mortars and to give them superior mechanical characteristics.
Sand and gravel are aggregates don't call them inert because:
Sand and gravel are technically called aggregates and not as they are erroneously inert because they can intervene in chemical reactions that lead to the solidification of mortars and concretes.
The aggregates are mainly sand and gravel.
However, not all the sands are suitable for use, in fact, the best ones are those without debris of other nature (earth or other impurities).
Those that contain salts such as marine sand are also to be considered unsuitable.
The grain size
The sands are divided according to the granulometry (the size of the grains that compose them) into fine, medium and coarse sand.
The greater the fineness of the sands and the greater their workability. The greater the size and quality of the aggregates, the greater their mechanical characteristics.
The granulometric division is obtained simply by passing the sands through special sieves.