Materials Lab
Fineness of Hydraulic Cement by Air Permeability
Apparatus (ASTM C204-96)
Prepared by:
Eng. Mohammed Mousa
The Islamic University of Gaza - IUG
Scope:
This test covers the determination of the fineness of hydraulic
cement using Blain air permeability apparatus, in terms of the
specific surface (the total surface area in cm2 per gram) of the
sample. The test consists of means of drawing a definite quantity
of air through a prepared bed of cement of definite porosity
which determines the rate of airflow through the bed.
Apparatus:
- Main Apparatus: consists of Manometer with four marks,
valve and taper at the top.
- Manometer liquid: A special type of low viscosity and low
density liquid to fill the U tube to level of lowest mark (fourth
mark).
- Permeability Cell: rigid, stainless steel, 12.7 mm inside
diameter cylinder.
- Perforated Disk: with 30-40 holes.
- Plunger: a stainless steel cylinder, with
3 mm flat side works as air vent.
- Filter paper.
- Timer.
- A balance of accuracy of 0.001g.
Procedures:
A. Preparation of bed of cement:
1. From calibration, the weight of the sample should be
determined such that the sample has a porosity of 0.500±0.0005
to fill the volume of the space between the plunger and the
perforated plate (about 2.80 g).
2. Put the perforated plate on the bottom of the cell, then a filter
paper on it.
3. Place the quantity of cement in the cell, tap the cell to level the
surface of cement and put a filter paper on the top of the bed of
cement.
4. Compress the cement with the plunger until the plunger collar is
in contact with the top of the cell. Withdraw the plunger, rotate
90° and press again, then withdraw it.
B. Permeability Test
5. Attach the cell to the taper connection of the manometer tube. A
little of grease should be applied to the taper connection to ensure
airtight connection.
6. Slowly evacuate the air in one arm of the manometer U tube
until the liquid reaches the first (top) mark. Close the valve.
7. Start the timer when the liquid reaches the second mark and
stop when the liquid reaches the third mark. Record the time
interval in seconds.
8. Record the room temperature during the test.
Calculations:
Calculate the specific surface of the sample as follows
𝐒 = 𝑺𝑺𝑻𝜼𝑺𝑻𝑺𝜼
𝐒 = 𝑺𝑺𝑻
𝑻𝑺
Where:
S: Specific surface of test sample (cm2/g)
Ss: Specific surface of standard cement (cm2/g)
T: Time interval of manometer drop for test sample
Ts: Time interval of manometer drop for standard cement (sec)
𝜼: Viscosity of air at temperature of the test of test sample as
given below.
𝜼𝒔: Viscosity of air at temperature of the test of standard cement.
34 32 30 28 26 24 22 20 18 16 Temperature
(°C)
18.76 18.67 18.57 18.47 18.37 18.28 18.18 18.08 17.98 17.88 Viscosity of air, 𝜼(𝝁𝑷𝒂. 𝒔)
ASTM C150-95 Requirements: specific surface, min. 2800 cm2/g.
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