ASTM C173/C173M-01
(Test Method)Standard Test Method for Air Content of Freshly Mixed Concrete by the Volumetric Method
Standard Test Method for Air Content of Freshly Mixed Concrete by the Volumetric Method
SCOPE
1.1 This test method covers determination of the air content of freshly mixed concrete containing any type of aggregate, whether it be dense, cellular, or lightweight.
1.2 The values stated in either inch-pound or SI units shall be regarded separately as standard. The SI units are shown in brackets. The values stated are not exact equivalents; therefore each system must be used independently of each other. Combining values from the two units may result in nonconformance.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: C 173/C 173M – 01
Standard Test Method for
Air Content of Freshly Mixed Concrete by the Volumetric
Method
This standard is issued under the fixed designation C 173/C 173M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope * 3.2 This test method requires the addition of sufficient
isopropyl alcohol, when the meter is initially being filled with
1.1 This test method covers determination of the air content
water, so that after the first or subsequent rollings little or no
of freshly mixed concrete containing any type of aggregate,
foam collects in the neck of the top section of the meter. If
whether it be dense, cellular, or lightweight.
more foam is present than that equivalent to 2 % air above the
1.2 The values stated in either inch-pound or SI units shall
water level, the test is declared invalid and must be repeated
be regarded separately as standard. The SI units are shown in
using a larger quantity of alcohol. Addition of alcohol to dispel
brackets. The values stated are not exact equivalents; therefore
foam any time after the initial filling of the meter to the zero
each system must be used independently of each other.
mark is not permitted.
Combining values from the two units may result in noncon-
3.3 The air content of hardened concrete may be either
formance.
higher or lower than that determined by this test method. This
1.3 This standard does not purport to address all of the
depends upon the methods and amounts of consolidation effort
safety concerns, if any, associated with its use. It is the
applied to the concrete from which the hardened concrete
responsibility of the user of this standard to establish appro-
specimen is taken; uniformity and stability of the air bubbles in
priate safety and health practices and determine the applica-
the fresh and hardened concrete; accuracy of the microscopic
bility of regulatory limitations prior to use.
examination, if used; time of comparison; environmental
2. Referenced Documents exposure; stage in the delivery, placement and consolidation
processes at which the air content of the unhardened concrete
2.1 ASTM Standards:
is determined, that is, before or after the concrete goes through
C 29/C 29M Test Method for Unit Weight and Voids in
a pump; and other factors.
Aggregate
C 138 Test Method for Unit Weight, Yield, and Air Content
4. Apparatus
(Gravimetric) of Concrete
4.1 Airmeter—An airmeter consisting of a bowl and a top
C 172 Practice for Sampling Freshly Mixed Concrete
section (Fig. 1) conforming to the following requirements:
C 231 Test Method for Air Content of Freshly Mixed
4.1.1 The bowl and top sections shall be of sufficient
Concrete by the Pressure Method
thickness and rigidity to withstand rough field use. The
C 670 Practice for Preparing Precision and Bias Statements
2 material shall not be attacked by high pH cement paste, deform
for Test Methods for Construction Materials
when stored at high temperatures in closed spaces, or become
3. Significance and Use brittle or crack at low temperatures. A watertight seal must be
obtained when the top section is attached to the bowl.
3.1 This test method covers the determination of the air
4.1.2 Bowl—The bowl shall have a diameter equal to 1 to
content of freshly mixed concrete. It measures the air contained
1.25 times the height and be constructed with a flange at or
in the mortar fraction of the concrete, but is not affected by air
near the top surface. Bowls shall not have a capacity of less
that may be present inside porous aggregate particles.
than 0.075 ft [2.0 L].
3.1.1 Therefore, this is the appropriate test to determine the
4.1.3 Top Section—The top section shall have a capacity at
air content of concretes containing lightweight aggregates,
least 20 % larger than the bowl and shall be equipped with a
air-cooled slag, and highly porous or vesicular natural aggre-
flexible gasket and a device to attach the top section to the
gates.
bowl. The top section shall be equipped with a transparent
scale, graduated in increments not greater than 0.5 % from 0 at
This test method is under the jurisdiction of ASTM Committee C09 on
the top to 9 %, or more, of the volume of the bowl. Graduations
Concrete and Concrete Aggregatesand is the direct responsibility of Subcommittee
C09.60 on Fresh Concrete Testing. shall be accurate to 60.1 % by volume of the bowl. The upper
Current edition approved March 10, 2001. Published June 2001. Originally
end of the neck shall have a watertight cap that will maintain
e1
published as C 173 – 42. Last previous edition C 173 – 94a .
a watertight seal when the meter is inverted and rolled.
Annual Book of ASTM Standards, Vol 04.02.
*A Summary of Changes section appears at the end of this standard.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
C 173/C 173M
calibrated cup is only to be used to add water when the
concrete air content exceeds 9 % or the calibrated range of the
meter.
4.6 Measuring Vessel for Isopropyl Alcohol—A vessel with
a minimum capacity of at least 1 pt [500 mL] with graduations
not larger than 4 oz [100 mL] for measuring a quantity of
isopropyl alcohol.
4.7 Syringe—A rubber syringe having a capacity of at least
2 oz [50 mL].
4.8 Pouring Vessel for Water—A container of approxi-
mately 1 qt [1 L] capacity.
4.9 Scoop—A small metal scoop.
4.10 Isopropyl Alcohol—Use 70 % by volume isopropyl
alcohol (approximately 65 % by weight) (Note 1). Other
foam-dispersing agents are permitted if tests demonstrate that
the use of the agent does not change the indicated air content,
in the amounts being used, by more than 0.1 % or if correction
factors are developed similar to those in Table 1. When other
dispersing agents are used, a copy of the records documenting
the testing or calculations shall be available in the laboratory.
NOTE 1—Seventy percent isopropyl alcohol is commonly available as
rubbing alcohol. More concentrated grades can be diluted with water to
the required concentration.
4.11 Mallet—A mallet (with a rubber or rawhide head) with
a mass of approximately 1.25 6 0.5 lb [600 6 200 g].
5. Calibration
5.1 Calibrate the meter and calibrated cup initially and
annually or whenever there is reason to suspect damage or
deformation of the meter or calibrated cup.
5.2 Determine the volume of the bowl with an accuracy of
at least 0.1 % by determining the mass of water required to fill
it at room temperature and dividing it by the density of the
water at the same temperature. Follow the calibration proce-
dure outlined in Test Method C 29/C 29M.
5.3 Determine the accuracy of the graduations on the neck
of the top section of the airmeter by filling the assembled
measuring bowl and top section with water to the level of the
FIG. 1 Apparatus for Measuring Air Content of Fresh Concrete by
mark for highest air content graduation.
Volumetric Method
5.3.1 Add water in increments of 1.0 % of the volume of the
bowl to check accuracy throughout the graduated range of air
4.2 Funnel—A funnel with a spout of a size permitting it to
content. The error at any point throughout the graduated range
be inserted through the neck of the top section and long enough
shall not exceed 0.1 % of air.
to extend to a point just above the bottom of the top section.
The discharge end of the spout shall be so constructed that
TABLE 1 Correction for the Effect of Isopropyl Alcohol on
C 173/C 173M Air Meter Reading
when water is added to the container there will be a minimum
disturbance of the concrete.
70 % Isopropyl Alcohol Used Correction
A
5 1
Pints Ounces Litres (Subtract)
4.3 Tamping Rod—A round, smooth, straight ⁄8 6 ⁄16-in.
B
[16 6 2-mm] diameter rod at least 12 in. [300 mm] long with 0.5 8 0.2 0.0
B
1.0 16 0.5 0.0
both ends rounded to a hemispherical tip of the same diameter.
B
1.5 24 0.7 0.0
The rod shall be made of steel, high-density polyethylene, or B
2.0 32 0.9 0.0
other plastic of equal or greater abrasion resistance. 3.0 48 1.4 0.3
1 3 4.0 64 1.9 0.6
4.4 Strike-off Bar—A flat, straight steel bar at least ⁄8 by ⁄4
5.0 80 2.4 0.9
by 12 in. [3 by 20 by 300 mm] or a flat, straight high-density
A
Subtract from final meter reading.
polyethylene bar, or other plastic of equal or greater abrasion
B
Corrections less than 0.125 are not significant and are to be applied only when
1 3
resistance, at least ⁄4 by ⁄4 by 12 in. [6 by 20 by 300 mm].
2.5 pt [1.2 L] or more alcohol is used. The effect occurs when the meter is inverted
after being filled with an alcohol-water solution which then becomes further diluted
4.5 Calibrated Cup—A metal or plastic cup either having a
when it is mixed with the water in the concrete. The values given are for air meters
capacity of or being graduated in increments equal to 1.00 6
that have a bowl volume of 0.075 ft [2.1 L] and a top section that is 1.2 times the
0.04 % of the volume of the bowl of the air meter. The volume of the bowl.
C 173/C 173M
added initially to avoid overfilling the meter. However, it is desirable to
5.4 Determine the volume of the calibrated cup using water
initially add at least some water initially to aid in mixing the alcohol and
at 70°F [21.1°C] by the method outlined in 5.2. A quick check
limit the contact of the concentrated alcohol with the top surface of the
can be made by adding one or more calibrated cups of water to
concrete.
the assembled apparatus and observing the increase in the
7.4 Displacing the Volume of Air in the Concrete Specimen
height of the water column after filling to a given level.
Using These Procedures:
6. Sampling
7.4.1 Free the Concrete from the Base— Quickly invert the
meter, shake the base horizontally, and return the meter to the
6.1 Obtain the sample of freshly mixed concrete in accor-
upright position. To prevent the aggregate from lodging in the
dance with Practice C 172. If the concrete contains coarse
1 neck of the unit, do not keep it inverted for more than 5
aggregate particles that would be retained on a 1 ⁄2-in. [37.5-
seconds at a time. Repeat the inversion and shaking process for
mm] sieve, wet sieve a representative sample over a 1-in.
a minimum of 45 seconds and until the concrete has broken
[25-mm] sieve to yield somewhat more than enough material to
free and the aggregate can be heard moving in the meter as it
fill the measuring bowl. The wet sieving procedure is described
is inverted.
in Practice C 172. Carry out the wet sieving operation with the
7.4.2 Rolling—Place one hand on the neck of the meter and
minimum practicable disturbance of the mortar. Make no
the other on the flange. Using the hand on the neck, tilt the top
attempt to wipe adhering mortar from coarse aggregate par-
of the meter approximately 45° from the vertical position with
ticles retained on the sieve.
the bottom edge of the base of the meter resting on the floor or
7. Procedure on the work surface. Maintain this position through the
procedures described in this section. Using the hand on the
7.1 Rodding and Tapping—Wet the inside of the bowl and
1 1
flange to rotate the meter, vigorously roll the meter ⁄4 to ⁄2 turn
dry it to a damp but not shiny appearance. Using the scoop, fill
forward and back several times, quickly starting and stopping
the bowl with freshly mixed concrete in two layers of equal
the roll. Turn the base of the meter about ⁄3 turn and repeat the
depth. Rod each layer 25 times with the tamping rod. Do not
rolling procedure as stated previously. Continue the turning
forcibly strike the bottom of the bowl when rodding the first
and rolling procedures for approximately 1 min. The aggregate
layer. When rodding the second layer, penetrate the prior layer
must be heard sliding in the meter during this process.
approximately 1 in. [25 mm]. After each layer is rodded, tap
7.4.2.1 If, at any time, during the inversion and rolling
the sides of the bowl 10 to 15 times with the mallet to close any
procedures liquid is found to be leaking from the meter, the test
voids left by the tamping rod and to release any large bubbles
is invalid and a new test shall be started as in 6.1.
of air that may have been trapped. After tapping the final layer,
1 7.4.2.2 Set the unit upright and loosen the top to allow any
a slight excess of concrete, ⁄8 in. [3 mm] or less, above the rim
pressure to stabilize. Allow the meter to stand while the air
is acceptable. Add or remove a representative sample of
rises to the top and until the liquid level stabilizes. The liquid
concrete if necessary to obtain the required amount of concrete.
level is considered stable when it does not change more than
7.2 Striking Off—After rodding and tapping of the second
0.25 % air within a 2-min period.
layer, strike off the excess concrete with the strike-off bar until
7.4.2.3 If it takes more than 6 min for the liquid level to
the surface is flush with the top of the bowl. Wipe the flange of
stabilize or if there is more foam than that equivalent to 2 full
the bowl clean.
percent air content divisions on the meter scale over the liquid
7.3 Adding Water and Alcohol—Wet the inside of the top
level, discard the trial and start a new test as in 6.1. Use a larger
section of the meter, including the gasket. Attach the top
addition of alcohol than was used in the initial trial.
section to the bowl and insert the funnel. Add at least 1 pt [0.5
7.4.2.4 If the level is stable without excessive foam, read the
L] of water followed by the selected amount (Note 2) of
bottom of the meniscus to the nearest 0.25 % and record the
isopropyl alcohol. Record the amount of isopropyl alcohol
initial meter reading.
added. Continue adding water until it appears in the graduated
7.4.2.5 If the air content is greater than the 9 % range of the
neck of the top section (Note 3). Remove the funnel. Adjust the
meter, add a sufficient number of calibrated cups of water to
liquid level until the bottom of the meniscus is level with the
bring the liquid level within the graduate range. Read the
zero mark. A rubber syringe is useful for this purpose. Attach
bottom of the meniscus to the nearest 0.25 %. Record the
and tighten the watertight cap.
number of calibrated cups of water to be added to the final
NOTE 2—The amount of isopropyl alcohol necessary to obtain a stable
meter reading in 8.1.3.
reading and a minimum of foam at the top of the water column will
7.5 Confirmation of the Initial Meter Reading:
depend upon a number of factor
...
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