ASTM C138/C138M-01a
(Test Method)Standard Test Method for Density (Unit Weight), Yield, and Air Content (Gravimetric) of Concrete
Standard Test Method for Density (Unit Weight), Yield, and Air Content (Gravimetric) of Concrete
SCOPE
1.1 This test method covers determination of the density (see Note 0) of freshly mixed concrete and gives formulas for calculating the yield, cement content, and air content of the concrete. Yield is defined as the volume of concrete produced from a mixture of known quantities of the component materials.
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 might not be exact equivalents; therefore each system must be used independently of the other.
Note 1--Unit weight was the previous terminology used to describe the property determined by this test method, which is mass per unit volume.
1.3 The text of this test method references notes and footnotes that provide explanatory information. These notes and footnotes (excluding those in tables) shall not be considered as requirements of this test method.
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American Association State
Designation:C138/C138M–01a Highway and Transportation Officials Standard
AASHTO No.: T121
Standard Test Method for
Density (Unit Weight), Yield, and Air Content (Gravimetric)
of Concrete
This standard is issued under the fixed designation C 138/C 138M; 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*
A = air content (percentage of voids) in the concrete
1.1 This test method covers determination of the density
3 3
C = actual cement content, lb/yd or kg/m
(see Note 1) of freshly mixed concrete and gives formulas for
C = mass of cement in the batch, lb or kg
b
calculating the yield, cement content, and air content of the
3 3
D = density (unit weight) of concrete, lb/ft or kg/m
concrete. Yield is defined as the volume of concrete produced
M = totalmassofallmaterialsbatched,lborkg(seeNote
from a mixture of known quantities of the component materi-
3)
als.
M = mass of the measure filled with concrete, lb or kg
c
1.2 The values stated in either inch-pound or SI units shall
M = mass of the measure, lb or kg
m
be regarded separately as standard. The SI units are shown in
R = relative yield
y
brackets. The values stated might not be exact equivalents;
T = theoretical density of the concrete computed on an
3 3
therefore each system must be used independently of the other.
airfree basis, lb/ft or kg/m (see Note 2)
Y = yield, volume of concrete produced per batch, yd or
NOTE 1—Unit weight was the previous terminology used to describe
the property determined by this test method, which is mass per unit m
volume. Y = volume of concrete which the batch was designed to
d
3 3
produce, yd or m
1.3 The text of this test method references notes and
Y = volume of concrete produced per batch, ft
f
footnotes that provide explanatory information. These notes
V = total absolute volume of the component ingredients
and footnotes (excluding those in tables) shall not be consid-
3 3
in the batch, ft or m
ered as requirements of this test method.
3 3
V = volume of the measure, ft or m
m
2. Referenced Documents
NOTE 2—The theoretical density is, customarily, a laboratory determi-
nation, the value for which is assumed to remain constant for all batches
2.1 ASTM Standards:
made using identical component ingredients and proportions. It is calcu-
C 29/C 29M Test Method for Bulk Density (Unit Weight)
lated from the following equation:
and Voids in Aggregate
T 5 M/V (1)
C 150 Specification for Portland Cement
C 172 Practice for Sampling Freshly Mixed Concrete
The absolute volume of each ingredient in cubic feet is equal to the
C 188 Test Method for Density of Hydraulic Cement
quotient of the mass of that ingredient divided by the product of its
C 231 Test Method for Air Content of Freshly Mixed
specific gravity times 62.4. The absolute volume of each ingredient in
Concrete by the Pressure Method
cubic metres is equal to the mass of the ingredient in kilograms divided by
C 670 Practice for Preparing Precision and Bias Statements
1000 times its specific gravity. For the aggregate components, the bulk
specific gravity and mass should be based on the saturated, surface-dry
for Test Methods for Construction Materials
condition. For cement, the actual specific gravity should be determined by
3. Terminology Test Method C 188. A value of 3.15 may be used for cements manufac-
tured to meet the requirements of Specification C 150.
3.1 Symbols:
NOTE 3—The total mass of all materials batched is the sum of the
masses of the cement, the fine aggregate in the condition used, the coarse
aggregate in the condition used, the mixing water added to the batch, and
This test method is under the jurisdiction of ASTM Committee C09 on
any other solid or liquid materials used.
Concrete and ConcreteAggregates and is the direct responsibility of Subcommittee
C09.60 on Fresh Concrete Testing.
Current edition approved March 10, 2001. Published May 2001. Originally
published as C 138 – 38 T. Last previous edition C 138 – 01.
Annual Book of ASTM Standards, Vol 04.02.
Annual Book of ASTM Standards, Vol 04.01.
*ASummary of Changes section appears at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C138/C138M–01a
4. Apparatus measures of 0.5 ft [14 L] or smaller, and a mallet having a
mass of 2.25 6 0.50 lb [1000 6 200 g] for use with measures
4.1 Balance—Abalance or scale accurate to 0.1 lb [45 g] or
larger than 0.5 ft .
to within 0.3 % of the test load, whichever is greater, at any
point within the range of use. The range of use shall be
5. Sample
considered to extend from the mass of the measure empty to
5.1 Obtain the sample of freshly mixed concrete in accor-
the mass of the measure plus its contents at 160 lb/ft [2600
kg/m ]. dance with Practice C 172.
4.2 Tamping Rod—A round, straight steel rod, ⁄8 in. [16
mm] in diameter and approximately 24 in. [600 mm] in length, 6. Procedure
having the tamping end rounded to a hemispherical tip the
6.1 Base the selection of the method of consolidation on the
diameter of which is ⁄8 in.
slump, unless the method is stated in the specifications under
4.3 Internal Vibrator—Internal vibrators may have rigid or
which the work is being performed. The methods of consoli-
flexible shafts, preferably powered by electric motors. The
dation are rodding and internal vibration. Rod concretes with a
frequency of vibration shall be 7000 vibrations per minute or
slump greater than 3 in. [75 mm]. Rod or vibrate concrete with
greater while in use. The outside diameter or the side dimen-
a slump of 1 to 3 in. [25 to 75 mm]. Consolidate concretes with
sion of the vibrating element shall be at least 0.75 in. [19 mm]
a slump less than 1 in. by vibration.
and not greater than 1.50 in. [38 mm]. The length of the shaft
NOTE 6—Nonplastic concrete, such as is commonly used in the
shall be at least 24 in. [600 mm].
manufacture of pipe and unit masonry, is not covered by this test method.
4.4 Measure—Acylindrical container made of steel or other
suitable metal (see Note 4). The minimum capacity of the 6.2 Rodding—Place the concrete in the measure in three
layers of approximately equal volume. Rod each layer with 25
measure shall conform to the requirements of Table 1 based on
the nominal size of aggregate in the concrete to be tested. All strokes of the tamping rod when nominal 0.5-ft [14-L] or
smaller measures are used, 50 strokes when nominal 1-ft
measures, except for measuring bowls of air meters which are
2 3
also used for Test Method C 138 tests, shall conform to the [28-L] measures are used, and one stroke per 3 in. [20 cm ]
of surface for larger measures. Rod the bottom layer through-
requirements of Test Method C 29/C 29M. When measuring
bowls of air meters are used, they shall conform to the out its depth but the rod shall not forcibly strike the bottom of
the measure. Distribute the strokes uniformly over the cross
requirements of Test Method C 231, and shall be calibrated for
volume as described in Test Method C 29/C 29M. The top rim section of the measure and for the top two layers, penetrate
about 1 in. [25 mm] into the underlying layer.After each layer
oftheairmeterbowlsshallbesmoothandplanewithin0.01in.
[0.3 mm] (see Note 5). is rodded, tap the sides of the measure 10 to 15 times with the
appropriate mallet (see 4.6) using such force so as to close any
NOTE 4—The metal should not be readily subject to attack by cement
voids left by the tamping rod and to release any large bubbles
paste. However, reactive materials such as aluminum alloys may be used
of air that may have been trapped. Add the final layer so as to
in instances where as a consequence of an initial reaction, a surface film
is rapidly formed which protects the metal against further corrosion. avoid overfilling.
NOTE 5—Thetoprimissatisf
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