To Determine the Particle Size Distribution of Coarse Aggregates by Sieve Analysis Method and to determine Fineness Modulus of Coarse Aggregates

To Determine the Particle Size Distribution of Coarse Aggregates by Sieve Analysis Method and to determine the Fineness Modulus of Coarse Aggregates.

What is particle size distribution?

The particle size distribution also applies to the Coarse Aggregates since these are naturally occurring or crushed in dispersed form, which means that they consist of differently shaped and sized particles. The particle size distribution, i.e. the number of particles of different sizes, is responsible for important physical and chemical properties.

Apparatus Required:

• Mechanical Sieve Shaker, Bowls, Weighing Machine

Material Required:

• Coarse Aggregate

THEORY:

Sieve Analysis Test: Sieve analysis enables us to ascertain the properties of different sizes of aggregates. The results which are generally given as a percentage of total aggregates passing through each size of the sieve are considered a method of standardization of grading of aggregates for the most economical mix and workability with a minimum quantity of cement.

Grading Zones: To describe an aggregate by its maximum and minimum sizes is not enough; it has to be graded from this minimum to maximum limits. The maximum and minimum limits to various aggregates in terms of their percentage passing are called grading limits.

Fineness Modulus: The term used as an idea about fines or coarseness of aggregate, or the mean size of aggregate particles. The fineness modulus is to be calculated as

F.M= sum of cumulative % of aggregates retained / 100

Note: the theory is the same as for the Fine Aggregate but the standard sieves will differ.

Procedure:

1. Dry the aggregate test sample in a constant weight at a temperature of 110°C
   then cool it down to the room.
2. Place the sieves in a mechanical sieve shaker in ascending order.
3. Agitate the sieve with a mechanical shaker for sufficient time.
4. The criteria for sieving is that after completion not more than 1% of the residue
   of any individual sieve will pass the sieve during one minute of hand sieving.
5. Find the percentage passing and record on the table.

Observations:

Results:

The Fineness Modulus of the given coarse aggregates is given out as

Review Questions:

1. How many types of standard sieves are there?
2. Discuss the suitability of the aggregate you tested in the laboratory for constructional purposes.