Test Method of Sand Silt content

[Dhaval Thanki]

Which is best method to find out accuracy of Silt content of Sand By 75 micron IS Sieving method OR By measuring cylinder method ?

 

[amd007]

For finding the percentage of silt content you have to take the measuring cylinder method only.

Sieve analysis basically gives you the FINENESS MODULUS meaning size of the particle on the sieve, it may also give you the silt content to some extent but won't be accurate when compared to the MEASURING CYLINDER METHOD as due to water being used as a washing media in MCM all silt attached to the sand will come off and deposit on top of the sand layer and this would be the true silt content.

Hope that satisfies your query.

 

[Dhaval Thanki]

For finding the percentage of silt content you have to take the measuring cylinder method only.

Sieve analysis basically gives you the FINENESS MODULUS meaning size of the particle on the sieve, it may also give you the silt content to some extent but won't be accurate when compared to the MEASURING CYLINDER METHOD as due to water being used as a washing media in MCM all silt attached to the sand will come off and deposit on top of the sand layer and this would be the true silt content.

Hope that satisfies your query.

What should be acceptable limit for silt content by volume ? As per IS 383 Table 2 , 3% allowed for un-crushed and 15% for crushed sand by Mass.

 

[amd007]

What should be acceptable limit for silt content by volume ? As per IS 383 Table 2 , 3% allowed for un-crushed and 15% for crushed sand by Mass.

Would like to mention here some of my thoughts in connection with the query raised by you.

All the acceptance criteria mentioned in the IS codes are based on sampling done by our learned members from our fraternity.

You should definitely follow the IS codes in case you do not have the facility for testing the specimens, and if you have the facility like conducting the MIX DESIGN then you can try out the sampling for various silt contents and arrive at a figure as per your test specimens.

For example: If I want a target strength for concrete of about M:25 then you can use test specimens with 3% , 6% , 9% etc of silt content, see the target compressive strength on various %'s and if it's achieved then you can freeze you allowable silt content.

As long as you are getting the desired strengths I don't find any reason why you cannot increase or decrease the silt content after all nowadays we are using fly ash, micro-silica, ggbs, and other fines in concrete to make the concrete durable.

If you are really keen on increasing your knowledge, go ahead and do MIX DESIGN FOR CONCRETE, MORTAR ETC for various silt contents and then arrive at your own practical constants for silt content.

All the information in IS codes or a matter of fact in any reference manual is based on practical experiences. Hope this answers your query. Good luck