What is fineness test of cement?
The test done for finding the fineness of cement by sieving the cement on the standard IS sieve is called the fineness test of cement. The proportion of cement size greater than 90 microns is considered as fineness cement. In other words, the fineness of the cement is the particle size of cement.
The maximum residue after the sieving in standard sieve should be limited to 10% by weight for OPC, and 5% by weight for rapid hardening cement.
Why is fineness test of cement done?
The fineness test of cement is done for:
1) Proper grinding of cement
Finer cement has the quicker action with water and get early strength.
2) Increasing surface area:
Finer the cement more surface area is covered by it.
3) Reducing bleeding:
Bleeding can be reduced by increasing the fineness of cement but it can lead to shrinkage as we have to increase the requirement of water.
How is the test carried out in the laboratory?
- 90-micron standard IS sieve with pan,
- Weighing machine
- Take some amount of cement and pour it in the sieve size of 90 microns.
- Shake the sieve horizontally so that the cement can pass through that sieve.
- After shaking, note the weight of the cement retain in the sieve.
- Repeat the process three time for more accurate result.
Calculation formula for Fineness test
Let, the initial weight of cement before pouring =W1
Let, the weight of cement retained after sieving= W2
The fineness of cement = % of cement retained= (W2/W1) * 100
Table of calculation:
|S. N||Weight cement sample||Weight of cement retained||Fineness %|
|1||Let, 100g||Let, 5g||5%|
|2||Let, 100g||Let, 4g||4%|
|3||Let, 100g||Let, 4.5g||4.5%|
|Average= 10.5 %|
Now, check if the fineness of the cement is acceptable:
|Cement||Maximum Fineness %|
|Rapid hardening cement||5%|
- The weight of the cement should be noted carefully.
- Sieve pan should be close while shaking so that no amount of cement can be lost.
- The calculation should be done carefully.
- The sample should be taken from the same type of cement while doing the fineness test of cement.
I hope this post remains helpful.
Happy Learning – Civil Concept
Civil Engineer – Shreya Parajuli