The aggregate, also called concrete aggregate or concrete gravel, together with the cement paste, forms the supporting structure of the concrete.
The aggregate has an influence on the physical properties of the concrete. Depending on the material of the concrete aggregate, the elastic deformation behaviour of the concrete may change. The concrete types with the limestone and sandstone aggregates have lower deformation property than the concrete types with the quartz or basalt aggregates.
The aggregate is classified on the basis of its grain composition, which is categorized by so-called grading curves. An important role for the concrete design and workability is played by the largest diameter of the aggregate used; it is also called the maximum grain.