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.