Air content test for fresh concrete

1. Air Content in Fresh Concrete
• To determine %age of Air Content in compacted Fresh Concrete
• Test is used to determine the Air Content, the test should be confirm to BS 1881
Part 106/EN 12350-7:2009 or ASTM C231, Pressure gauge Method
• In this method, the operational principle consists of introducing water to a
predetermined height above a sample of concrete of known volume and the
application of a predetermined air pressure over the water.
• Samples should be collected as per standard method of sampling
• Air Content act as reservoir for water and control cement bleeding
Apparatus/Tools
• Air Entrainment Meter 8 liter or 5 liter Capacity
• Air Entrainment meter consist of cover assembly that contain the following parts:
a)Cover with interior pressure chamber, left ball shut-off valve (A) (use to fill the
water in meter) right (B) ball shut-off valve (use to release air bubble from meter
while filling water , and quick-release latches to clamp the cover assembly with
container.

2. b.) Cap with pressure-gauge (use to check pressure and %age air
content in concrete), Switch panel with integrated hand pump that
have screw at top to be locked while transporting ( use to apply air
pressure),
• TEST valve (green color), correction valve (black color)
• A flanged type cylinder vessel 5 liter or 8 liter capacity, ratio of
diameter to height not less than 0.75 nor more than 1.25 & be
suitable for 100 KN/m2
• Tamping bar made of hard wood having squire section side of 46+-1
mm and length 200 mm and further 120 mm to 150 mm shall be
turned to a circular shape
• scoop, about 100 mm
• Sampling tray 900x900x50mm
• Squire type shovel

4. Procedure
• Fill concrete sample in test container in three layers with compaction to
each layer to minimize maximum air voids in concrete.
• Wipe off extra material from the top and level the surface of container.
• Thoroughly clean the flanges of container, specially the ceiling edge.
• Place the cover assembly on container and line up the red dots of cover
assembly and container and then close the clamps/quick release
latches.
• beat slightly out side of the container with rubber hammer to release
any trapped air
• Open valves A & B, tilt the machine toward valve A, inject the water by
squeeze bottle in valve A
• Complete this operation until the water is free of air bubble
• Close both the valves A & B
• Using the hand pump rise the air pressure in pressure chamber until the
needle of pressure gauge stop behind the last Red Mark

5. • Wait few seconds so that air pressure will reach to ambient
temperature
• slightly press the Black Correction button on machine so that the
needle rest on first Red line
• Tape slightly the pressure gauge with fingers and press the green
button to release the air pressure until the need is stable
• Strike slightly sides of cover assembly to release any trapped air and
press the green button
• Note the air content of compacted fresh concrete in percentage.
• After completing test open valve A & B
• open the quick release latches and remove the cover assembly from
container
• Press the green test button to release all air pressure until the needle
reach to initial position i.e. beyond 100%

6. Needle Position on pumping Air Pressure Needle Position after pressing Black Correction Button

7. Calibration of Air Entrainment Meter
• Take off the cover assembly from the container
• Fix the 8 mm supply hose under the valve A in cover assembly
• Fill up the container with water and close it with cover
assembly
• Open both valve A & B tilt the machine toward valve A and fill
the water with squeeze bottle until the water is free of air
bubble
• Close both the valves A & B
• Using the hand pump rise the p air pressure in pressure
chamber until the needle of pressure gauge stop behind the last
Red Mark
• Wait few seconds so that air pressure will reach to ambient
temperature

8. • slightly press the Black Correction button on machine as the
needle rest on first Red line
• Tape slightly the pressure gauge with fingers to and press the
green button to release the air pressure until the need is
stable
• If the needle rest on “0” means the machine is ok, if not the
pressure gauge cover should be open to adjust the scale with
“0” reading
• Repeat the test to check if the correction are successful i.e.
the pressure needle stand on 0%
• If the initial pressure correct then start calibration of Air
Content of Machine by screwing 4 mm tube out side of valve
A

9. • Keep the graduated cylinder on balance and make the weight of
cylinder as “0”
• Hold the tube in graduated cylinder of 500 ml capacity
• Open valve A and press green button to flow the water in cylinder as
mentioned below
• If 1 liter test container used remove 100 g (10%) of water from
container, while total amount of water required to fill the container is
1000 gm
• If 5 liter test container used remove 250 g (5%) of water from
container, while total amount of water required to fill the container is
5000 gm
• If 8 liter test container used remove 400 g (5%) of water from
container, while total amount of water required to fill the container is
8000 gm
• Close the valve A

10. • Using the hand pump rise the p air pressure in pressure chamber until the
needle of pressure gauge stop behind the last Red Mark
• Wait few seconds so that air pressure will reach to ambient temperature
• slightly press the Black Correction button on machine as the needle rest on
first Red line
• Tape slightly the pressure gauge with fingers and press the green button to
release the air pressure until the need is stable
• Check the corresponding air pressure, if 1 liter container used it should be
10%
• Check the corresponding air pressure, if 5 liter container used it should be
5%
• Check the corresponding air pressure, if 8 liter container used it should be
5%
• Calibration is completed

11. 8 mm supply hose position of red dots while closing cover assembly on container
position of machine while filling water 4 mm tube with valve A

12. Filling of water in cylinder