Definition
Aggregate is a granular material used in construction, such as sand, gravel, crushed stone, slag, or recycled concrete. Aggregates are the most mined materials in the world and serve as the primary filler in concrete mixes (60-75% of concrete volume), asphalt, and road base. They provide structural strength, dimensional stability, and reduce shrinkage in cement products.
Formula
Aggregates compact when placed. For gravel, multiply the loose volume by 1.1-1.15 to account for compaction. A 10x10x0.33 foot area requires about 33 cubic feet of loose gravel, but only 29 cubic feet after compaction.
Example
Concrete Mix Example
A standard 1:2:3 concrete mix uses 1 part cement, 2 parts sand (fine aggregate), and 3 parts gravel (coarse aggregate) by volume. For a 1-cubic-yard batch, you need approximately 7 cubic feet of sand and 10.5 cubic feet of gravel. Aggregates should be clean, hard, and free of absorbed chemicals or coatings.