How to determine the 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 Blaine air permeability test of cement.


Fineness Test of Cement by Blaine Air Permeability Method as per IS: 4031 Part-2 (1988) | Blaine Air Permeability test of Cement

Fineness Test of Cement by Blaine Air Permeability Method as per IS: 4031 Part-2 (1988) | Blaine Air Permeability test of Cement


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IS Code for Fineness Test of Cement by Blaine Air Permeability Method:-

  • IS: 4031 Part-2 (1988): For determination of fineness of cement.


Other References:-

  • IS 3535 (1980): For methods of sampling hydraulic cements.
  • IS 5516 (1996): For specification of variable flow type air permeability apparatus (Blaine Air Permeability Apparatus).

Range of testing:- 100 to 700 m²/kg



Apparatus Used for Fineness Test of Cement by Blaine Air Permeability Method:-

  1. Blaine Air Permeability Apparatus: Conforming to IS 5516 (1996).
  2. Timer/ Stopwatch: Capable of reading to the nearest 0.2 s or better and accurate to 1 percent.
  3. Weighing balance: Capable of weighing up to 3 g to the nearest 1 mg (for cement).
  4. Weighing balance: Capable of weighing about 50 g to 110 g to the nearest 10 mg (for mercury).
  5. Pycnometer or other convenient: For determining the density of cement.
  6. Manometer liquid: A non-volatile, non-hygroscopic liquid of low viscosity and density, such as dibutyl phthalate or light mineral oil.
  7. Light oil: To prevent formation of mercury amalgam on the inner surface of the cell.
  8. Mercury: of reagent grade or better.
  9. Circular discs of filter paper: Having a smooth circumference and of medium porosity (Mean pore Diameter = 7μm).
  10. Light grease: For ensuring an airtight joint between cell and manometer and in the stopcock.
  11. Cement sample: of known specific surface.

Sampling and Selection of Test Specimens:-

The samples of the cement will be taken according to the requirements of IS 3535:1980 (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 Requirements:-

The temperature of moulding room, all materials for test and calibration should be maintained at a temperature of 25 °C to 29 °C and the relative humidity level not exceeding 65%. All materials for test and calibration should be protected from absorption of atmospheric moisture during storage. The temperature may be determined at 18 °C to 22 °C, if desired by the purchaser.



Procedure of Fineness Test of Cement by Sieve Analysis:-


Part-A

Compaction of Cement Bed:-

  1. Take the cement sample of known specific surface to be tested.
  2. Agitate the sample for 2 minutes in a stoppered jar to disperse agglomerates.
  3. Wait for 2 minutes and stir the resulting powder gently by using a clean dry rod in order to distribute the fines throughout the cement.
  4. Determine the density of the cement (ρ) using a device such as a pycnometer or Le-chatelier flask.
  5. Determine the mass of cement to be used for calibration, using the following formula assuming porosity e = 0.500. M1 = 0.5 × ρ × V. Where, ρ = Density of cement (3.15 g/cm³ for OPC) and V = Volume of cement bed (in cm³).
  6. Apply very thin layers of light mineral oil to the cell interior.
  7. Place the perforated disc on the ledge at the bottom of the cell.
  8. Place two new filter paper discs on top of the perforated ensuring its full coverage and flatness.
  9. Fill the cell with mercury. Remove any air bubbles with a clear dry rod. Ensure that the cell is full by pressing a glass plate on the surface of the mercury until it flushes with the cell of top.
  10. Empty the cell and weight the mercury (M2).
  11. Remove one filter paper disc from the cell.
  12. Place the perforated disc on the ledge in the bottom of the cell. Place a new filter paper disc on top of the perforated disc ensuring its full coverage and flatness.
  13. Take a trial quantity of cement (approximately 2.8 g).
  14. Place the cement sample into the cell. Tap the cell to level the cement.
  15. Place a second new filter paper disc on the leveled cement.
  16. Insert the plunger to make contact with the filter paper disc and press it gently but firmly, until the lower face of the cap of the plunger is in contact with the cell.
  17. Slowly withdraw the plunger about 5 mm, rotate it by 90° and gently but firmly press the bed once again until the plunger cap is in contact with the cell.
  18. The cement bed is now compacted and ready for air permeability test.
  19. If the plunger does not touch the surface of the cell after step, reduce the trial quantity of cement. If the plunger falls in easily without being pressed by the plunger, increase the trial quantity of cement.
  20. Refill the cell with mercury as describe from step (14 to 17).
  21. Remove the mercury and weight it to get M3.
  22. Calculate the bed volume as under.



Where,

V = Bed volume in (cm³),
M2 and M3 as calculated above and
D = Density of mercury.


Part-B

Determination of the Apparatus Constant:-

  1. From a supply of standard reference cement of known specific surface, prepare a compacted cement bed (as Part-A: Compaction of cement bed).
  2. Measure its permeability by the procedures given in Part-C.
  3. Record the time as tₒ and the temperature of test using the same bed.
  4. Repeat twice the procedure on the same cement bed and record the additional values of time and temperature.
  5. Repeat the whole procedure on two further samples of the same cement sample. For each of the three samples calculated the means of the three times and temperatures.
  6. For each sample calculate the apparatus constant, K as following formula and take the mean of the three values of K as the constant K for the apparatus.



Where,

Sₒ = Specific surface of the standard reference cement, cm²/g.
tₒ = the time recorded for the manometer drop for the standard reference cement (mean of 3 reading).
Ƞₒ = viscosity of air at the room temperature.
ρₒ = Density of reference cement sample in g/cm³.


Part-C

Air Permeability Test of Cement Sample:-

  1. Insert the conical surface of the cell into the socket at top of the manometer. (Use if necessary a little light grease to ensure an airtight joint and take care not disturb the cement bed.)
  2. Close the top of the cylinder with a suitable plug.
  3. Open the stopcock and raise the manometer liquid to the level of the highest etched line on the cylinder.
  4. Close the stopcock and ensure that the level of the manometer liquid remains constant.
  5. If it falls, remake the cell-manometer joint and check the stopcock, repeat the leakage test until the improved sealing produces a steady level of the liquid. Open the stopcock and by gentle aspiration adjust the level of the liquid, to that of the highest etched line. After this close the stopcock.
  6. Remove the plug form the top of the cylinder.
  7. The manometer liquid will begin to flow.
  8. Start the timer as the manometer liquid reach the second etched line.
  9. Stop the timer as the manometer liquid reaches the third etched line.
  10. Record the time as t to the nearest 0.2 second and the temperature to the nearest 1 °C.
  11. Repeat twice the procedure on the further samples of the same cement bed and record the additional values of time and temperature.
  12. Calculate the specific surface or fineness of cement sample as under at 25 °C to 29 °C, at e = 0.500.



Where,

K = apparatus constant as calculated earlier.
S = Specific Surface area of the standard reference cement cm²/g
t  = measured time t (mean of two value)
ρ = Density of cement


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