Aggregates form a major component of concretes,typically approximately 80% by weight in cured mass concrete. Aggregate properties, including crushing strength, size, grading and shape, have significant effects on the physical properties of the concrete mixes and hardened concrete. In addition, the appearance of visual concrete may be influenced by aggregate colour and surface treatments. The standard BS EN 12620: 2013 specifies the appropriate properties including materials, size, grading and shape.

Aggregates for concrete are normally classified as lightweight, dense or high density. Standard dense aggregates are classified by size as fine (e.g. sand) or coarse (e.g. gravel). In addition, steel or polypropylene fibres or air/gas bubbles may be incorporated into the mix for specialist purposes.