gravel or coarse aggregate is one of the main components of concrete, for this reason its quality is extremely important to guarantee good results in the preparation of concrete structures.

The coarse aggregate will be made up of crushed rock or gravel obtained from previously selected sources and analyzed in the laboratory to certify its quality. The minimum size will be 4.8 mm. The coarse aggregate must be hard, resistant, clean and free of foreign materials or dust, which, if present, must be eliminated by an appropriate procedure, such as washing.

The shape of the smallest particles of coarse crushed rock or gravel aggregate shall be generally cubic and shall be reasonably free of thin, flat or elongated particles in all sizes.[1]​.

In general, the coarse aggregate must be in accordance with the ASTM C 33 standard (The use of the standard is subject to the country in which it is applied since the specifications of each of these vary according to the region or country). The percentages of harmful substances in each fraction of the coarse aggregate, at the time of discharge at the concrete plant, must not exceed the following limits:.

The coarse aggregate must be well graded between the fine and coarse limits and must arrive at the separated concrete plant in normal sizes whose granulometries are indicated below:

Unless specifically indicated otherwise, the maximum size of the aggregate that must be used in the different parts of the work will be:.

See also Gunitado.