How To Do Sieve Analysis Of Aggregate

2019-08-14 civilsitevisit

Sieve analysis is one of the important practices in civil engineering as it is used for finding particle size distribution of particular aggregate. It is also used for finding the fineness modulus of aggregate.

Concrete mix designs can be influenced by the size of coarse aggregate to be used. so it is important to find the particle size of Aggregate. This is done by sieving the aggregates as per IS: 2386 (Part I) The test sample is dried to a constant weight at a temperature of 110 + 5^oC and weighed.

Process :-

Using the sieve sizes required by the specification, arrange sieves in descending order with the largest size on top. A set of IS Sieves of sizes – 80mm, 63mm, 50mm, 40mm,31.5mm, 25mm, 20mm, 16mm, 12.5mm, 10mm, 6.3mm,4.75mm, 3.35mm, 2.36mm, 1.18mm, 600µm, 300µm, 150µm and 75µm.
If using a mechanical sieve shaker, place the set of sieves onto a pan and pour the prepared aggregate onto the top sieve, cover the stack of sieves and pan, turn on the machine, and set it to shake for at least 5 minutes.
If hand sieving, start with the largest size, and progress toward the smaller sieve sizes; move the sieves in lateral and vertical motions accompanied by a jarring action to keep the material moving continuously over the surface of the sieves. Hand manipulation without forcing particles through the sieve is permitted.

Note : For either mechanical or hand sieving, sieve the material until not more than 1% by mass of the residue on any individual sieve will pass that sieve during 1 minute of continuous hand sieving.
Using a scale with a capacity large enough to obtain the mass of the total sample, determine the mass of the fine aggregate to the nearest 0.1 g and coarse aggregate to the nearest 1 g

First, determine the mass of the aggregate retained on the largest sieve size and record the value.
Add the contents of the next largest sieve size on the scale, obtain the cumulative mass of the two sizes and record this mass.
Finally, add the contents of the next size, and repeat this operation until the contents of the smallest sieve size used is empty, and cumulative mass has been obtained and recorded.
When the specifications require percent passing, record the weights retained on each sieve individually.

Note —For sieves with openings smaller than the 4.75 mm (No. 4), the mass retained on any sieve at the completion of the sieving operation should not exceed 6 kg/m2 (4 g/in.2 ) of sieving surface.

No more than 200 g of material should be retained on any single 203 mm (8 in.) diameter sieve.

CALCULATIONS

Calculate percent retained: PR = 100( MR / MTS )

Where: PR = Percent Retained

MR = Mass Retained

MTS = Mass of Total Sample.

Note :-For both the coarse and fine aggregate laboratory methods, use the total dry mass prior to washing as the basis for calculating all the percentages.