The silt is a very fine particle which is less than the size of 150 Microns. It will shrink and expand due to the moisture also unstable with the presence of water.
So it is important to check the presence of silt content in the sand to avoid the following impacts
Impact of Silt Presence in Sand
It absorbs more water.
Cracks will be developed on concrete.
It will affect bonding between cement and aggregates.
Silt content contains evaporated matters and salts.
Unstable with water. This is the reason why mortar is peeling off every time when mason tries to plaster
Allowable silt content presence on sand is 6% or 7%.
Silt Content Test for Sand
The test conducted to identify the percentage of silt content present in the sand is known as the Silt Content Test.
Let’s discuss this in detail.
Required Apparatus
Measuring cylinder – 250 ml
Sand – Specimen
Water
Salt Solution
Test Procedure
The measuring cylinder should be free from moisture and dry.
Fill the water up to 50 ml with a 1% salt solution.
Then fill the sand into the cylinder up to the level of 100 ml.
Again add salt solution up to the level of 150 ml.
Finally, close the mouth of the cylinder and shake well then keep the cylinder on a flat surface.
The silt content shall be settled over the sand layer after 2 hours.
Why is salt added with sand?
To increase the settlement time of silt which impacts the testing time. First, Sand will settle then silt content settle at the end.
How to calculate the percentage of Silt?
V1 = Volume of Silt layer (Silt settled over the sand layer).
V2 = Volume of the Sand layer (Settled under the silt).
