Question

The size of aggregate bigger than __________ is considered as coarse aggregate.
1. 5.25 mm
2. 5 mm
3. 4.25 mm
4. 4.75 mm

Answer 1

Correct Answer - Option 4 : 4.75 mm

Explanation:

According to the ISSC system size of coarse aggregates starts from 0.075 mm or 75 microns and ends at 80 mm.

So sieve of 4.75 mm and 10 mm are normally used for classification in coarse aggregates.

The table below shows the tabular data for different sieve suitable for different sizes of aggregates.

Very coarse soils	Boulder size		> 300 mm
	Cobble size		80 – 300 mm
Coarse soils	Gravel size (G)	Coarse	20 – 80 mm
		Fine	4.75 – 20 mm
	Sand size (S)	Coarse	2 – 4.75 mm
		Medium	0.425 – 2 mm
		Fine	0.075 – 0.425 mm
Fine soils	Silt size (M)		0.002 – 0.075 mm
	Clay size (C)		< 0.002 mm