What Is Fineness Modulus of Sand?

Fineness modulus of aggregate is an index number which gives an idea about the finance of aggregate and is an approximate proportion of the average size of particle in the aggregate. It is found out by sieve analysis test of standard size in the laboratory. The thumb rule is lower the fineness modulus, particles are smaller and higher the fineness modulus, particles are larger.

What is Fineness Modulus of Sand?

Objective

To determine the fineness modulus of fine aggregate.

Equipment and Apparatus 

  1. Set of sieve
  2. Weighing machine   
  3. Tray
  4. Sand Specimen

Procedure

  1. Take s suitable sample of fine aggregate and take the weight of it.
  2. Now place the sample in the set of IS sieves arrange in descending order  10 mm, 4.75 mm, 2.36mm, 1.18 mm, 600 microns,  300 microns and 150 microns.
  3. Now put the lid at the top of IS sieve set and put the complete assembly in a sieve shaker and shake it for 15 minutes.
  4. After proper sieving fraction of sand of different sizes will be retained on different sieves.
  5. Take the weight of each fraction and note down it in the observation sheet.

Observation

For example,

Weight of Sample = 2000 gm.    Specification : IS: 383 – 1970

IS Sieve DesignationWeight of sample retained(gm)Cumulative weight of  retained (gm)Cumulative % of weight retained% of weight Passing
10mm000000100
4.75 mm22221.198.9
2.36 mm1121346.793.3
1.18 mm20033416.783.3
600 microns29062431.268.8
300 microns1112173286.613.4
150 microns222195497.72.3
Pan4620001000

Note –

1. Cumulative % of weight retained = Cumulative weight of retained / Sample weight  × 100

2. % of weight Passing  =  (100 – Cumulative % of weight retained)

Fineness modulus = (Summation of cumulative % of weight retained up to 150 microns) / 100

Fineness modulus  = 240/100

Fineness modulus  = 2.4

So, in our case, it is Fine Sand.

Value of fineness Modulus of  Sand

Type of SandFineness Modulus
Fine sand2.2 – 2.6
Medium Sand2.6 – 2.9
Coarse Sand2.9 – 3.2

Zone of Sand As Per IS: 383-1970

IS SieveZone 1Zone 2Zone 3Zone 4
10 mm100100100100
4.75 mm90 – 10090 – 10090 – 10090 – 100
2.36 mm 60 – 9575 – 10085 – 10095 – 100
1.18 mm30 – 7055 – 9075 – 10090 – 100
600 microns15 – 3435 – 5960 – 7980 – 100
300 microns5 – 208 – 3012 – 4015 – 50
150 microns0 – 100 – 100 – 100 – 15

By percentage of weight Passing, we can find out the zone of sand by comparing the value from the table listed above. In our case, it matches from zone 3.

Weight of  Sample As Per IS: 2386 (Part – 1) – 1963

Maximum size present in substantial proportion in (mm)Minimum weight of the sample to be taken for sieving in (Kg)
6350
5035
40 – 31.515
255
20 – 162
12.51
100.5
6.30.2
4.750.2
2.360.1

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Also, read

Silt Content Test For Sand

Soundness Test of Cement

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