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What is fineness test of cement?
Fineness test of cement is a laboratory test done to determine the proportion of the size of particles of cement greater than 90 microns.
Fineness test of cement done in two ways –
(a) By Sieving
(b) Air permeability method ( Generally Blaine air permeability apparatus is used)
In this article, we are going to learn the sieve method to determine the fineness of cement. In this method cement sample is sieving through a standard IS sieve of 90 microns.
The percentage of cement particles of size more than 90 microns that are retained on the sieve is called fineness of cement.
Importance of Fineness Test Of Cement-
- With increase in fineness of cement rate of hydration increases.
- Finer cement act quickly with water and gain early strength.
- Fineness also affects workability, with in increase in fineness workability is also increases.
- With increase in fineness of cement surface area of cement particles increases which absorbs more water and if it cement particle grind beyond limit it will cause shrinkage in concrete.
- Setting time of cement decreases with increase in fineness. Hence cement ground in different grades as per requirement of setting time.
- With increase in fineness of cement amount of bleeding in concrete is decreases.
From the above points, it is clear that fineness is one of most the important properties of cement. So it is required to test the fineness of cement is to be within limits before its use in construction.
Fineness test of cement by dry sieving –
The fineness of cement is determined by Dry sieving method as follow-
Apparatus-
Standard IS 90 micron Sieve with lid
Weighing Balance – Which is capable of weighing 10g to the nearest 10mg.
Sieve shaker machine
Nylon bristol brush – For cleaning of the sieve.
Procedure-
1) Take some amount of cement and rub the cement with fingers to remove the lumps.
2) Now take 100g of cement from that sample and note down it as W1.
3) Pour this cement sample in IS 90 micron sieve and close this sieve with a lid
4) Now place this sieve in the sieve shaking machine and shake for 2 minutes or you can shake the sieve with your hand for 15 minutes.
5) After this, weigh the cement that is retained on a sieve and note it as W2.
6) Now calculate the fineness percentage as per the following formula –
Fineness of cement sample = (W2/W1) * 100
7) Repeat the above process with three different samples of cement and calculate the average of them for accuracy.
Calculations-
Let’s take an example for a better understanding.
W1 = Weight of cement sample
Here we take 100g of cement sample for test. Therefore, W1 = 100g.
Now, Let assume 5g of cement sample is retained on 90 micron IS sieve after the sieving process.
Therefore, W2 = Weight of cement which is retained on sieve = 5g.
Fineness % of cement = (W2/W1)*100 = (5/100)*100 = 5%
To eliminate the errors, repeat the process 3 times and take an average of these 3 values.
| Weight of cement sample (W1) | Weight of cement retained on sieve (W2) | Fineness % of cement |
| 100g | 5g | 5% |
| 100g | 6g | 6% |
| 100g | 4g | 4% |
Average Fineness % of cement = 5%
Fineness limit of various types of cement-
As per IS: 4031 (Part 1) – 1996 percentage of cement retained on sieve should not more than following percentages-
1) Ordinary portland cement = 10%
2) Rapid hardening cement = 5%
3) Low heat cement = 5%
Precautions –
Cement Samples taken for the test should be dry and free from lumps.
Rub the cement sample gently to remove the lumps if any.
Weighing should be done very accurately.
Sieving should be done by wrist action to prevent losses.
Read More: How to check quality of cement on site
FAQs on fineness test of cement-
How does the fineness of cement affects the stregth of cement?
With the increase in fineness of cement rate of hydration of cement increases. Which increases the rate of strength gaining process of cement.
What is the size of the sieve used in the fineness test of cement?
Standard IS sieve of size 90 microns is used in the fineness test of cement.
How does too much fineness is affect the cement?
Too much finer particles in cement set the cement very quickly results in no time for handling and placing of cement.
What is standard value of fineness of cement?
The standard value of fineness of cement should be less than 10% as per IS : 4031 (PART 1) 1996
Also, read – How to store cement on site