* 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 **

- Set of sieve
- Weighing machine
- Tray
- Sand Specimen

**Procedure**

- Take s suitable sample of fine aggregate and take the weight of it.
- 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.
- 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.
- After proper sieving fraction of sand of different sizes will be retained on different sieves.
- 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.

**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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