How do you calculate fineness of cement?

Fineness of cement can be calculated by using air permeability method or by using sedimentation method or from particle size analysis (sieve analysis). Sieve analysis (dry sieving) measures the cement particle size whereas air permeability method and sedimentation method measures specific surface area of cement. Here we have explained about particle size analysis (sieve analysis) of cement.



The fineness of cement by sieve analysis is measured by sieving it on standard sieve. The proportion of the sample of cement of which the grain sizes are larger than the specified mesh size is thus determined.

A reference sample of cement having a known proportion of material coarser than the specified mesh size is used for checking the specified sieve.



Why fineness test of cement is done?

In almost all cement tests, the fineness test of cement is to be determined. Fineness test is used in checking the proper grinding of cement and measuring the surface area of the cement particles per unit mass. As well as fineness of cement increases, the requirement of water for workability also increases which results in a higher possibility of dry shrinkage.


Fineness of Cement IS Code, Test Procedure, Apparatus List and Lab Report by Sieve Analysis as per IS: 4031 Part-1 (1996)  Dry Sieving of Cement
Apparatus Used for Fineness of Cement by Sieve Analysis


Fineness of Cement by Sieve Analysis as per IS: 4031 Part-1 (1996)


Hi friends, you are welcomed in the Civil Allied Gyan. Read definition, apparatus list, IS code, test procedure, observations, formula, result and lab report about fineness of cement of by sieve analysis.



IS Code for Fineness of Cement Test by Sieve Analysis:-

  • IS: 4031 Part-1 (1996): For determination of fineness of cement.


Other References:-

  • IS: 460 Part-1 (1985): For specification of sieves.
  • IS 3535 (1986): For methods of sampling hydraulic cements.
  • IS 5165 (1969): For interchangeable conical ground-glass joints 



Apparatus Used for Fineness Test of Cement by Sieve Analysis:-

  1. 90 μ IS Sieve with pan as per IS: 460 (Part 1 and 3): 1985
  2. Sieve lid
  3. Weighing balance capable of weighing up to 100 g to the nearest 10 mg
  4. A nylon or pure bristle brush, preferably with 25 mm to 40 mm bristle, for cleaning the sieve
  5. Gauging trowel
  6. Tray
  7. Tamping rod
  8. Sieve Shaking Machine (optional)



Fineness of Cement Sieve Size:-

The size of sieve used in finding fineness of cement is 90 μ IS sieve with pan as per IS: 460 (Part 1 and 3): 1985.

It comprises a firm, durable, non-corrodible, cylindrical frame of 150 mm to 200 mm nominal diameter and 40 mm to 100 mm depth, fitted with 90 pm mesh sieve cloth of woven stainless steel, or other abrasion-resisting and non-corrodible metal wire.



Material for Checking the Sieve:-

A Standard reference material of known sieve residue shall be used for checking the sieve.

The material shall be stored in sealed, airtight containers to avoid changes in its characteristics due to absorption or deposition from the atmosphere. The containers shall be marked with the sieve residue of the reference material.



Sampling and Selection of Test Specimens:-

The samples of the cement will be taken according to the requirements of IS 3535:1986 (Methods of sampling hydraulic cements) and the relevant standard specification for the type of cement being tested.

Mix thoroughly the representative sample of the cement, selected as above, before testing.



Temperature and Humidity:-

The temperature of moulding room, dry materials and water will be maintained at 25 °C to 29 °C. The relative humidity of the laboratory will be 60 to 70 percent.

The moist closet or moist room will be maintained at 25 °C to 29 °C and at a relative humidity of not less than 90 percent.



Procedure of Fineness Test of Cement by Sieve Analysis:-

  1. Agitate the representative sample of the cement to be tested by shaking for 2 minutes in a stoppered jar to disperse agglomerates (lumps).Wait for 2 minutes and stir the resulting cement powder gently using a clean dry rod in order to distribute the fines throughout the cement.
  2. Accurately weigh 100 g of cement for test sample to the nearest 0.01 g and place it on the sieve being careful to avoid loss.(Total weight of cement, W)
  3. Rub the cement particle well with your fingers so that no air set lumps are left and agglomerates are dispersed.
  4. Fit the lid over the sieve.
  5. If you have a sieving machine then you just need to put the sieve in the sieving machine and start the machine for 15 minutes.
  6. If you don’t have the sieving machine then no problem, you can shake it also with your hands. Hold the sieve with pan in both hands and sieve with gentle wrist motion, in circular and vertical motion for a period of 15 minutes without any spilling of cement until no more fine material passes through it.
  7. Place the cover on the sieve and remove the pan.
  8. Now tap the other side of the sieve with the handle of brush and clean the outer side of the sieve.
  9. Now weigh the retained amount of cement on the sieve. (Weight of cement sample left on the sieve, W)
  10. Empty the pan and fix it below the sieve.
  11. Repeat the whole procedure, at least three times, using a fresh 100 g sample of cement to be tested.
  12. Totally sieve for 15 minutes and weigh the residue (weight of cement left over the sieve).
  13. Calculate the fineness of cement by formula W/W₁⨉100 % (also given below) for each time. Then express the fineness of cement as the average of the three values.
  14. Check the sieve after every 100 sieving.



Observations:-

1.Weight of cement taken =................

2.Weight of cement retained on the sieve =................

3.Type of cement =................

4.Brand of cement=.................

5.Room temperature=..................



Table: Observation Table for Fineness of Cement

Observations

Trail No. 1

Trail No. 2

Trail No. 3

Weight of Sample

 

 

 

Weight of Residue of Cement

 

 

 

% of Fineness of Cement

 

 

 

Weight of Residue of Fly Ash

 

 

 

% of Fineness of Fly Ash

 

 

 



Calculations:-

Formula for Fineness of Cement by Sieve Analysis:-



Result:-

Fineness of the given cement-sample is = …………… %



Limit:-

According to Indian Standard, the amount of cement-retained on the 90 µm sieve will never exceed 10 %. i.e. the fineness of cement should be lower than 10%.



Report:-

Report the value of the fineness of cement, to the nearest 0.1 percent, as the residue on the 90 pm sieve for the cement tested.

The standard deviation of the repeatability is about 0.2 percent and of the reproducibility is about 0.3 percent.



Safety and Precautions While Testing:-

  1. Clean the apparatus thoroughly before testing and after testing.
  2. The test should be performed away from vibrations and other disturbances.
  3. Wear helmet, shoes and hand gloves during the test.
  4. The weighing should be done accurately.
  5. Make sure that the sieving operation is done in all the direction for a minimum of 15 minutes.
  6. Sieving will be done holding the sieve in both hands and gentle wrist motion; this will involve no danger of spilling the cement, which will be kept well spread out on the screen. More or less continuous rotation of the sieve will be carried out throughout sieving.
  7. Washers, shots and slugs will not be used on the sieve. The underside of the sieve will be lightly brushed with a 25 or 40 mm bristle brush after every five minutes of sieving.
  8. Mechanical sieving devices (Sieve Shaking Machine) may be used, but the cement will not be rejected if it meets the fineness requirement when tested by the hand method.



FAQs

What is the degree of fineness of cement?

The degree of fineness of cement is a measure of the average (mean) size of the grains. The finer cement has quicker action with water and gains early strength without change within the ultimate strength. Finer cement is susceptible to shrinkage and cracking.



What is the unit of fineness of cement?

The fineness of cement is a measure of the size of cement-particles. In sieve analysis of cement, fineness of cement is calculated by ratio of weight of cement-sample retained on the sieve with total weight of cement-sample. Thus there is no unit of fineness of cement.

While in air permeability method or sedimentation method, the fineness of cement is expressed in terms of the specific surface area of cement. Specific surface is expressed as the total surface area in square meter of all the cement particles in 1 kg of cement. Thus, the unit of fineness of cement is m²/kg. Higher the specific surface, finer the cement.



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