Aggregates are classified as
- Fine aggregate
- Coarse aggregate
Fine aggregate
The material which passes through I.S. sieve No.480 [4.75mm] and retained on I.S. sieve No. 5 [0.05mm] is considered as fine aggregate e.g. natural sand, surkhi etc. according to the grain size, the sand is termed as follows.
| Size | Type of sand |
|---|---|
| 0.06 to 1mm | Very fine sand |
| 1 to 3mm | Harfine sand |
| 3 to 4.75 | Coarse sand |
Coarse aggregate
The material which passes through an 80mm sieve and retained on I.S. sieve No.480 [4.75mm] is considered as coarse aggregate. E.g. pebbles, gravel, and if 30mm it is called fine gravel, and if 30 to 80mm is called course gravel. Depending on the size of course aggregate it is used for different works as follows.
| Size | Use |
|---|---|
| 200 to 75mm | Mass concrete foundation, dams |
| 50 to 75mm | Roadwork |
| 24 to 50mm | Plain concrete work |
| 15 to 20mm | R.C.C. works |
| 10 to 12mm | Thin R.C.C. section, curtain walls |