What Is Fineness Modulus of Sand?

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.

Objective

To determine the fineness modulus of fine aggregate.

Equipment and Apparatus 

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

Also, Read – Rate Analysis for Cement Plaster.

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 Designation	Weight of sample retained(gm)	Cumulative weight of  retained (gm)	Cumulative % of weight retained	% of weight Passing
10mm	00	00	00	100
4.75 mm	22	22	1.1	98.9
2.36 mm	112	134	6.7	93.3
1.18 mm	200	334	16.7	83.3
600 microns	290	624	31.2	68.8
300 microns	1112	1732	86.6	13.4
150 microns	222	1954	97.7	2.3
Pan	46	2000	100	0

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.

Also, Read – How to Calculate Cement, Sand and Aggregate Quantity in Concrete?

Value of fineness Modulus of  Sand

Type of Sand	Fineness Modulus
Fine sand	2.2 – 2.6
Medium Sand	2.6 – 2.9
Coarse Sand	2.9 – 3.2

Zone of Sand As Per IS: 383-1970

IS Sieve	Zone 1	Zone 2	Zone 3	Zone 4
10 mm	100	100	100	100
4.75 mm	90 – 100	90 – 100	90 – 100	90 – 100
2.36 mm	60 – 95	75 – 100	85 – 100	95 – 100
1.18 mm	30 – 70	55 – 90	75 – 100	90 – 100
600 microns	15 – 34	35 – 59	60 – 79	80 – 100
300 microns	5 – 20	8 – 30	12 – 40	15 – 50
150 microns	0 – 10	0 – 10	0 – 10	0 – 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)
63	50
50	35
40 – 31.5	15
25	5
20 – 16	2
12.5	1
10	0.5
6.3	0.2
4.75	0.2
2.36	0.1

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Also, read

Silt Content Test For Sand

Soundness Test of Cement

Unit Weight of Building Materials Used in construction.

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