How to Calculate Fineness modulus of aggregate| Formula with Numerical

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What is fineness modulus of aggregate?

The fineness modulus of aggregate is simply a measurement of the average size of the aggregate. It can be calculated with the help of different sizes of the sieve. Now, let us see some numerical Examples to calculate the fineness modulus of aggregate.

How to Calculate Fineness modulus of aggregate| Formula with Numerical

Q.1) Find the fineness modulus of coarse aggregates for which the sieve analysis is given it the table below:

Weight of sample = 10 kg

Solution:-

Coarse aggregate

IS sievi (mm)Weight retained 9(kg)Cumulative weight retained(kg)Cumulative% retained
75 mm000
40 mm000
20 mm2.52.5(2.5/10)*100=25
10 mm4.57(7/10)*100=70
4.75 mm2990
2.36 mm110100
1.18 mm100
600 micron100
300 micron100
150 micron100
 Total685

So,

Fineness modules(F.M.)

=685/100

=6.85

Q.2) Find the F.M of coarse aggregate and fine aggregate form the sieve analysis data as given in the table below:

Weight of sample = 15 kg

Solution:-

Coarse aggregate

IS sieve (mm)Weight retained(kg)Cumulative weight retained (kg)Cumulative% retained
75mm000
40mm000
20mm77(7/15)*100=46.67
10mm613(13/15)*100=86.67
10mm215100
4.75mm100
2.36100
1.18100
600micron100
300micron100
150micron100
  total733.34
    

 Fineness modules (F.M.) = 733.34/100    =7.33

Total weight of fine aggregate = 500gm

Fine aggregate

IS sieve(mm)Weight retained (kg)Cumulative  weight retained (kg)Cumulative% retained
75mm
40mm
20mm
10mm000
4.75mm55(5/500)*100=1
2.365560(60/500)*100=12
1.185511523
600micron9020541
300micron17037575
150micron9046593
Lower than 150 micron35500100(not unit)
  total245

 NOTE*

Weight lower than 150 micron is not considered in calculation :-

Fineness modules (F.M.) = 2.45

Q.3) A sieve analysis was carried out for 5 kg aggregate in the laboratory with available sieves. The weights retained in sieve of 40,32,20,16,10,4.75,are 0,1.2,1.8,0.5,1.5and 0 kg respectively. Obtain fineness modules for the sample.

Solution:

IS sieve(mm)Weight retained(kg)Cumulative weight retained (kg)Cumulative% retained
40mm000
32mm1.21.224
20mm1.8360
16mm0.53.570
10mm1.55100
4.7505100
  total354
    

COMULATIVE % weight retained = (commutative weight retained/total weight)*100%

Fineness modules (F.M.) = (total cumulative % weight retained)/100         

=354/100 

= 3.54


I hope this article on “Fineness modulus of aggregate” remains helpful to you.

Happy Learning – Civil Concept

Contributed by,

Civil Engineer – Ranjeet Sahani

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