Sand plays the vital role in every part of the construction (concrete, plastering, brickwork, flooring).

So it is essential to ensure that we are using good quality of sand.

Why we measure the Silt Content in the sand?

Silt content is a fine material which is less than 150 micron. It is unstable in the presence of water.

It is unstable in the presence of water. If we use silty sand for bonding, it will reduce the strength and cause rework.

You may be experienced this while plastering for a roof where the mason tries to plaster the mortar where it gets continually peel off.

Excessive quantity of silt, not only reduces the bonding of cement and fine aggregates but also affects the strength and durability of work. You can check out this article for silt and clay properties.

In the field, we have to conduct silt test for every 20 Cum of sand. This may vary.

Silt Content Test for Sand

Objective

Find out silt content in sand (fine aggregate)

Apparatus required

250 ml measuring cylinder
Water
Sand & Tray

Test Procedure

First, we have to fill the measuring cylinder with 1% solution of salt and water up to 50 ml.
Add sand to it until the level reaches 100 ml. Then fill the solution up to 150 ml level.
Cover the cylinder and shake it well (as shown in video)
After 3 hours, the silt content settled down over the sand layer
Now note down the silt layer alone volume as V1 ml (settled over the sand)
Then note down the sand volume (below the silt) as V2 ml
Repeat the procedure two more times to get the average

The permissible Silt content in sand percentage is only 6%.

Silt Content test sand report

DETERMINATION OF SILT CONTENT
OBSERVATION SHEET
S.NO	DESCRIPTION	SAMPLE NO
S.NO	DESCRIPTION	SAMPLE 1	SAMPLE 2	SAMPLE 3
1	Volume of Sample (V1) ml
2	Volume of Silt (V2) ml
3	Percentage of Silt (V2/V1) * 100
	Average

You can also download this observation sheet in PDF Format

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