Fineness test of cement by Blaine air permeability apparatus
Test Standard : IS 4031-Part II
Apparatus for Fineness of cement by Blaine air permeability Test
- Blaine air permeability test apparatus
- Timer with accuracy of 0.2s accurate to 1% over time interval of 300s
- weighing balance of accuracy 0.001 and 0.01gms
- Le-chatlier’s flask for determining density of cement
- Manometer fluid
- Mercury of reagent grade
- Reference cement of known specific surface
- Circular discs of filter paper of medium porosity having mean pore diameter of 7µm
Testing Conditions for Fineness of cement by Blaine air permeability Test:
- Agitate the sample of cement to be tested by shaking for 2minutes in a stopped jar to disperse agglomerates.
- Testing laboratory shall be maintained at a temperature of 27± 20C
- relative humidity not exceeding 65%
Determination of Density of cement for fineness test
Formation of compacted cement bed (Calculate Quantity of test sample)
Cement bed of porosity e= 0.500weigh of cement sample = 0.50x P x V
Where P= density of the cement (gm/cc)V= Volume of the cement bed
This mass correctly compacted will produce a bed of porosity e=0.500.
Place the weighed quantity of cement M1, gms in the cell taking care to avoid losses. Tap the cell to level the cement and place a new filter paper disc on the levelled cement. Insert the plunger to make contact with the filter paper disc, press the plunger gently but firmly until the lower face of the cap is in contact with the cell. Slowly withdraw the plunger about 5.0mm, rotate it through 90 degrees and gently but firmly press the bed once again until the plunger cap is in contact with the cell which makes the bed compacted.
CALIBRATION OF THE TEST APPARATUS
Determination of the Bed Volume
contact with the filter paper disc, press the plunger gently but firmly until the lower face of the cap is in contact with the cell. Slowly withdraw the plunger about 5.0mm, rotate it through 90 degrees and gently but firmly press the bed once again until the plunger cap is in contact with the cell. The bed is now compacted and fill the remaining portion of the cell with mercury, remove any air bubbles and level the surface as before. Remove the mercury, weigh it to the nearest 0.01gms, say m3 and record the temperature.
The cement bed volume (V) is given by = (m2-m3)/D
Where D is the density of the mercury at the test temperature taken from below table
Repeat the procedure with fresh cement beds until two values of V are obtained differing by 0.005 cm3. Record the mean of these two values as V.
Determination of Apparatus constant:
So = Specific surface of the reference cement (cm2/g)
Po = Density of the reference cement (g/cm3)
No = Air viscosity at the mean of three temperature (Pa. s)
to = Mean of the three measure times (s)
The mean of the three values of K will be the constant K for the apparatus.
Measuring permeability :
Permeability for Fineness of cement by Blaine air permeability Test:
From the test sample of cement, calculate the mass of the cement and prepare a compacted cement bed.Insert the conical surface of the cell into the socket at the top of the manometer, using if necessary a little grease oil to ensure an airtight joint.
Close the top of the cylinder with a suitable plug, open the stopcock and with a gentle aspiration raise the level of the manometer fluid to that of the highest etched line, close the stopcock and observe that the level of the manometer fluid remains constant. If it fails, remake the cell manometer joint and check the stopcock, repeat the leakage test until the improved sealing produces a steady level of the fluid.
Open the stopcock and by gentle aspiration adjust the level of the fluid to that of the highest etched line. Close the stopcock. Remove the plug from the top of the cylinder. The manometer liquid will began to flow. Start the timer as the liquid reaches the second etched line and stop it when it reaches the third etched line.
Record the time (t) to the nearest 0.2s and temperature to the nearest 1.0 degree Celsius. Repeat the procedure on the same bed and record additional values of time and temperature. Prepare a fresh bed of same cement with second sample and follow the same procedure and carry out the permeability test twice and record the values of time and temperature as before.
Specific surface (cm2/g) of each of the test sample shall be calculated as:
S= {K x (sqrt e 3)x (sqrt t)}/ {P x (1-e) x sqrt (0.1N)}
Where
K= apparatus constant
e= Porosity (0.500)
t= Mean of the measured time (s)
P= density of the cement (g/cm3)
N= Air viscosity at test temperature (Pa S)
Mean value of specific surface shall be calculated and reported to the nearest 1.0 m2/Kg as specific surface of the cement.
Results Calculation terms
- Where the porosity is e = 0.500, the four times and temperatures resulting from the procedure shall be examined to check that the temperatures all fall within the specified range of 27 If: 2°C or 20 + 2’C.
- The resulting value of S, to the nearest 10 cm2/gm, shall be reported as the specific surface of the cement.
- A difference of 1 percent between the means of the fineness measurements carried out on two different powder beds from one and the same sample is acceptable.
- The standard deviation of the repeatability is about 50 cm2/g3 and of the reproducibility is about 100 cm2/gm.
- Where the porosity e is not = 0.500, equation 5 shall be used and the result to the nearest 10 cm2/gm reported as the specific surface of the cement.
- If, owing to a breakdown in control or for other reasons, the four temperatures do not lie within the specified range of 27 + 2°C or 20 + 2°C a value of S shall be reported, to the nearest 10 cm2/g, as specific surface of the cement.
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