Fineness modulus is an empirical factor obtained by adding the cumulative percentages of aggregate retained on each of the standard sieves ranging from 80 mm to 150 micron and dividing this sum by 100.
Why to Determine Fineness Modulus?
Fineness modulus is generally used to get an idea of how coarse or fine the aggregate is. More fineness modulus value indicates that the aggregate is coarser and small value of fineness modulus indicates that the aggregate is finer.
Fineness modulus of different type of sand is as per given below.
Type of Sand
Fineness Modulus Range
2.2 – 2.6
2.6 – 2.9
2.9 – 3.2
Generally sand having fineness modulus more than 3.2 is not used for making good concrete.