To Determine the Air Content of Fresh Concrete By Air Meter.

To Determine the Air Content of Fresh Concrete By Air Meter.

1.      Eqpt/ Materials:

            Air meter, air Pump, fresh Concrete, Tamping rod

2.      Procedure

a.       Place the miced concrete in three layers in the bowl of air meter and compact each layer by exactly 25 blows of the tamping rod. Tap the exterior surface of the measure 10 to 15 times after each rodding or until no large bubble of air appear.

b.      Strike off the surface flush using sawing motion with the straigth edge and wipe the flance clean

c.       Clamp the cover of the air meter and add water to zero mark

d.      Tap the sides after adding part of water to remove the enrapped air.

e.       Apply the air pressure of 15 psi by means of air pump and read the air content on the graduated gauge glass.

f.       Release the pressure and read level at zero pressre.

g.      Air Content is the difference in height at specified pressure and reading at zero pressure.

3.       Precaution:

a.       Always use fresh mix concrete.

b.      Bowl of air meter should be filled in three equal layers and each layer should be tamped 25 times with tamping rod.

c.       Clamp the ring tightly.

4.      Details  of reading/ obsns/ data to be recorded/ collected:

a.       Reading at specified pressure (15 psi)            =          A         =          4.25

b.      Reading at zero pressure                                 =          B         =          3.05

c.       Air Content                                                     =          A-B     =          1.1

5.      Interpretaion /collection/ obsns , reading, grapgh, etc leading to results

To be done with the standard specification of ASTM, C 231-97

6.      Comments:

      More the difference b/w the zero pressure and specified pressure, more is the air content   and vice versa.