Aggregate is a broad category of coarse to medium grained particulate material used in Construction. Aggregates are particles greater than 4.75mm, but generally range between 9.5mm to 37.5mm in diameter.
Aggregates are classified into 2 types based on size
When the aggregate is sieved through 4.75mm sieve, the aggregate retained is called coarse aggregate. Medium Gravel, Coarse Gravel , cobble and boulders come under this category.
The maximum aggregate size used may be dependent upon some conditions. In general, 40mm size aggregate used for normal strengths and 20mm size is used for high strength concrete. the size range of various coarse aggregates given below.
||4mm – 8mm
||8mm – 16mm
||16mm – 64mm
||64mm – 256mm
When the aggregate is sieved through 4.75mm sieve, the aggregate passed through it called as fine aggregate. Natural sand is generally used as fine aggregate, silt and clay are also come under this category. The soft deposit consisting of sand, silt and clay is termed as loam. The purpose of the fine aggregate is to fill the voids in the coarse aggregate and to act as a workability agent.
||2.0mm – 0.5mm
||0.5mm – 0.25mm
||0.25mm – 0.06mm
||0.06mm – 0.002mm
12 mm Aggregate: Coarse aggregate whose size are approximate 12mm are called 12mm Aggregate
20mm Aggregate: Coarse aggregate whose size varies in the range 10mm to 20 mm
40mm Aggregate: Coarse aggregate whose size varies in the range 20mm to 40 mm