Fineness Modulus of Sand: Procedure, Calculation & Result

The fineness modulus of sand is a value that indicates the coarseness or fineness of sand particles. It is commonly used in the construction industry to determine the amount of sand to be used in concrete mixtures, as well as to ensure consistency and quality of the sand used in construction projects.

A lower fineness modulus indicates finer sand particles, while a higher value suggests coarser particles. The fineness modulus is essential in concrete mix design, helping engineers achieve the desired workability and strength by adjusting the proportions of different aggregate sizes.

Fineness Modulus of Sand

The fineness modulus of sand is a measure of the average size of the sand particles. It is a dimensionless number that indicates how coarse or fine the sand is. The fineness modulus is calculated by summing up the cumulative percentages retained on a set of sieves and dividing the sum by 100.

To find the fineness modulus of fine aggregate required IS sieve are sizes of 4.75mm, 2.36mm, 1.18mm, 0.6mm, 0.3mm, and 0.15mm.

Fineness Modulus of Sand Test

IS Code for Fineness Modulus of fine aggregate: IS: 383 -1970

Apparatus

• Sieves as per IS standards
• Mechanical sieve shaker(optional)
• Dry oven
• Digital weight scale

Sample Preparation

Sample preparation for fineness modulus of sand is given as under

Take a sample of sand in a pan and placed it in the oven at a temperature of approximately 100-110°C.

After drying, take the sample out of the oven and note down its weight using a digital weighing scale.

Sieve Analysis of Fine Aggregate

Following is the test procedure for the fineness modulus of the sand test,

1) Take the sieves and arrange them in descending order with the largest sieve on top.

2) If a mechanical shaker is used for shaking, then put the sieve set in position on the mechanical shaker and pour the sample in the top sieve & then close it with the sieve plate.

3) Then switch on the machine and shaking of sieves should be done at least for 5 minutes.

                                                            

4) If the shaking is done manually (by the hands) then pour the sample in a top sieve and close it then hold the top two sieves and shake it inwards and outwards, vertically and horizontally.

5) After some time shake 3 and 4 and finally last sieves simultaneously.

6) After sieving, record the sample weights retained on each sieve. Then find the cumulative weight retained.

7) Finally, determine the cumulative percentage retained on each sieve.

8) Add all cumulative percentage values and divide by 100 then we will get the value of fineness modulus.

Calculation of F.M. of Sand

Let us assume the dry weight of the sample = 1000gm

After sieve analysis, the values that appeared are tabulated below.

Sieve size	Weight retained(g)	Cumulative weight retained (g)	Cumulative percentage weight retained(%)
4.75mm	0	0	0
2.36mm	100	100	10
1.18mm	250	350	35
0.6mm	350	700	70
0.3mm	200	900	90
0.15mm	100	1000	100
Total			275

Hence, Fineness modulus of Sand = (Cumulative % retained) / 100

= (275 / 100)

= 2.75

Range of Fineness of Modulus

The following table indicates sand fineness modulus value ranges from 2.6 to 3.2.

Types of Sand	Fineness Modulus (F. M) Value
Fine Sand	2.6 – 2.6
Medium Sand	2.6 -2.9
Coarse Sand	2.9 -3.2

Fineness modulus with respect to various zones of sand according to IS 383-1970 are given in the table below.

Sieve size	Zone1	Zone2	Zone3	Zone4
10mm	100	100	100	100
4.75mm	90-100	90-100	90-100	95-100
2.36mm	60-95	75-100	85-100	95-100
1.18mm	30-70	55-90	75-100	90-100
0.6mm	15-34	35-59	60-79	80-100
0.3mm	5-20	8-30	12-40	15-50
0.15mm	0-10	0-10	0-10	0-15
Fineness Modulus	4.0-2.71	3.37-2.1	2.78-1.71	2.25-1.35

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