Test for silt content in sand./Procedure for finding the silt present in the sand.

 Materials required:

1. 250ml. measuring cylinder.

2. Sand to be tested.

3. Water.

4. Table salt.

Procedure:

1. Take 50 ml. of water in the measuring cylinder. Add a pinch of salt (approx. 2gm.) to the water present in the jar. Let the salt dissolve in the water.

2. Add 50ml. of sand sample into the jar so that the water level will touch the 100ml. mark over the jar.

3. Again add 50ml. of the water & salt so that the new water level reaches 150ml. mark over the jar.

4. Close the open end of the measuring jar with your palm & shake it vigorously so that sand particles get washed up by the water. The jar should be turned up & down several times. Do this action for 15 to 20 sec. & take care that no materials come out of the jar while shaking.

5. The mixture is then allowed to settle down by keeping the jar on the floor for about 3 to 4 hours. The silt present in the sand starts settling over the sand in the jar ( as shown in below fig.)

6. Now, we have to note down the volume of silt & sand separately from observing the markings given over the jar. 

Suppose, if the volume of silt = V1 ml. 

             & the volume of sand = V2 ml.

Then the percentage of silt content in sand 

  = [V1 ➗ V2] Χ100  %

V1 = [(top-level reading of silt) - (bottom-level reading of silt or reading of sand)]

V2 = Top-level reading of sand.

In any case, the silt content in the sand should not be above 8%. If the sand contains more than 8% of silt, then such sand should be rejected.

In my opinion, the silt content in the sand should not be more than 6%. Otherwise, there is a chance of microscopic cracks in plastering work.

Calculation eg:

The volume of the silt = V1 = 3ml.

The volume of sand = V2 = 52 ml.

Percentage of silt content in sand

=  [V1 ➗ V2] Χ100  %

 = [3 ➗ 52] Χ100  %

 = 5.77% < 6%  ✔ OK

Note: 

1. Salt acts as a catalyst in enhancing the settlement process of silt over sand.

2. If you are using a measuring cylinder of a larger volume, keep in mind that the volume of water should be 2/3 of the total volume & sand should be 1/3 of the total volume for getting better results.

3. Repeat the test procedure with at least 3 samples, so that your test result will be nearer to accuracy.

What we should do, if the sand contains more than 8% of silt?

We should use a sand washing machine to remove the excess silt present in the sand.

Go through the article 👇

👀. Different types of sand washing machines.

To go through the field & laboratory tests conducted in civil engineering,  click here.

Thank you for going through this test procedure❤. Have a good day 😄.

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