ASTM C138/C138M-23

Standard Test Method for Density (Unit Weight), Yield, and Air Content (Gravimetric) of Concrete

ABSTRACT
This test method covers determination of the density of freshly mixed concrete and gives formulas for calculating the unit weight, yield or relative 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. The test method shall use the following apparatuses: balance or scale; tamping rod, which is a round straight steel rod having the tamping end rounded to a hemispherical tip; internal vibrator which may have rigid of flexible shafts, preferably powered by electric motors; measure, which is a cylindrical container made of steel or other suitable metal specified herein; strike-off plate; mallet; and scoop of a size large enough so each amount of concrete obtained from the sampling receptacle is representative and small enough so it is not spilled during placement in the measure.
SCOPE
1.1 This test method covers determination of the density (see Note 1) 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 SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.
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 refers to notes and footnotes that provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of this standard.  
1.4 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.(Warning—Fresh hydraulic cementitious mixtures are caustic and may cause chemical burns to skin and tissue upon prolonged exposure.2)  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Jul-2023
• ICS: 91.100.30 - Concrete and concrete products
• Technical Committee: C09 - Concrete and Concrete Aggregates
• Drafting Committee: C09.60 - Testing Fresh Concrete

Relations

• Refers: ASTM C31/C31M-24a - Standard Practice for Making and Curing Concrete Test Specimens in the Field
• Effective Date: 01-Apr-2024
• Refers: ASTM C173/C173M-24 - Standard Test Method for Air Content of Freshly Mixed Concrete by the Volumetric Method
• Effective Date: 01-Jan-2024
• Refers: ASTM C31/C31M-24 - Standard Practice for Making and Curing Concrete Test Specimens in the Field
• Effective Date: 01-Jan-2024
• Refers: ASTM C231/C231M-24 - Standard Test Method for Air Content of Freshly Mixed Concrete by the Pressure Method
• Effective Date: 01-Jan-2024
• Refers: ASTM C29/C29M-23 - Standard Test Method for Bulk Density (“Unit Weight”) and Voids in Aggregate
• Effective Date: 01-Oct-2023
• Refers: ASTM C1758/C1758M-23 - Standard Practice for Fabricating Test Specimens with Self-Consolidating Concrete
• Effective Date: 01-Oct-2023
• Refers: ASTM C173/C173M-23 - Standard Test Method for Air Content of Freshly Mixed Concrete by the Volumetric Method
• Effective Date: 01-Sep-2023
• Refers: ASTM C125-19a - Standard Terminology Relating to Concrete and Concrete Aggregates
• Effective Date: 15-Dec-2019
• Refers: ASTM C150/C150M-19 - Standard Specification for Portland Cement
• Effective Date: 01-Apr-2019
• Refers: ASTM C125-19 - Standard Terminology Relating to Concrete and Concrete Aggregates
• Effective Date: 01-Jan-2019
• Refers: ASTM C125-18b - Standard Terminology Relating to Concrete and Concrete Aggregates
• Effective Date: 01-Oct-2018
• Refers: ASTM C125-18a - Standard Terminology Relating to Concrete and Concrete Aggregates
• Effective Date: 01-Jul-2018
• Refers: ASTM C31/C31M-18 - Standard Practice for Making and Curing Concrete Test Specimens in the Field
• Effective Date: 01-Jan-2018
• Refers: ASTM C125-18 - Standard Terminology Relating to Concrete and Concrete Aggregates
• Effective Date: 01-Jan-2018
• Refers: ASTM C29/C29M-17 - Standard Test Method for Bulk Density (“Unit Weight”) and Voids in Aggregate
• Effective Date: 01-Jan-2017

Overview

ASTM C138/C138M-23 is the internationally recognized standard test method for the determination of density (unit weight), yield, and air content (gravimetric) of freshly mixed concrete. Developed by ASTM International, this method specifies precise procedures and equipment for measuring the mass per unit volume of concrete, calculating the quantity produced per batch, estimating cement content, and determining the air content via gravimetric means. Compliance with this standard ensures consistency and quality in concrete testing, which is critical for construction, quality control, and research across the civil engineering and construction industries.

Key Topics

• Density (Unit Weight) Measurement: Specifies techniques to determine the mass per unit volume of fresh concrete using calibrated containers and accurate balances.
• Yield Calculation: Defines procedures for calculating the actual volume of concrete produced relative to the designed mix, revealing the efficiency of the batching process.
• Air Content (Gravimetric): Provides formulas for determining air void content by comparing measured and theoretical densities, crucial for assessing durability and performance.
• Cement Content Determination: Outlines calculations for actual cement content in the concrete mix, helping verify compliance with mix design specifications.
• Standardized Apparatus: Details equipment requirements, including balances, tamping rods, cylindrical measures, strike-off plates, mallets, and scoops for reliable and repeatable results.
• Dual Units Compliance: Supports both SI and inch-pound units, ensuring applicability in international projects.

Applications

ASTM C138/C138M-23 is widely applied in various sectors and scenarios, including:

• Quality Control in Concrete Production: Ensures that fresh concrete meets project specifications for density, yield, and air content, which directly affect strength and durability.
• Batch Verification: Used by ready-mix plants and on construction sites to confirm that the intended batch quantities yield the required volume of concrete.
• Field and Laboratory Testing: Suitable for both field and laboratory environments to monitor the conformity of concrete as placed in structures such as pavements, bridges, buildings, and precast elements.
• Assessment of Material Properties: Enables engineers to assess the effects of material changes or adjustments to mix designs, such as variations in cementitious materials, aggregate sources, and admixtures.
• Regulatory and Contract Compliance: Meets requirements for reporting essential concrete properties in compliance with project specifications, government regulations, and quality assurance protocols.

Related Standards

ASTM C138/C138M-23 is part of a broader suite of standards that govern concrete testing and materials assessment:

• ASTM C29/C29M: Test Method for Bulk Density (“Unit Weight”) and Voids in Aggregate
• ASTM C31/C31M: Practice for Making and Curing Concrete Test Specimens in the Field
• ASTM C125: Terminology Relating to Concrete and Concrete Aggregates
• ASTM C143/C143M: Test Method for Slump of Hydraulic-Cement Concrete
• ASTM C150/C150M: Specification for Portland Cement
• ASTM C172/C172M: Practice for Sampling Freshly Mixed Concrete
• ASTM C173/C173M: Test Method for Air Content of Freshly Mixed Concrete by the Volumetric Method
• ASTM C188: Test Method for Density of Hydraulic Cement
• ASTM C231/C231M: Test Method for Air Content of Freshly Mixed Concrete by the Pressure Method
• ASTM C1758/C1758M: Practice for Fabricating Test Specimens with Self-Consolidating Concrete

For best practices in concrete quality control, consulting these related standards alongside ASTM C138/C138M-23 supports comprehensive and accurate assessment of fresh concrete properties, ensuring long-term performance and regulatory compliance in construction projects.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: C138/C138M − 23 American Association State
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 C138/C138M; 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 (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope* mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.1 This test method covers determination of the density
(see Note 1) of freshly mixed concrete and gives formulas for
2. Referenced Documents
calculating the yield, cement content, and air content of the
2.1 ASTM Standards:
concrete. Yield is defined as the volume of concrete produced
C29/C29M Test Method for Bulk Density (“Unit Weight”)
from a mixture of known quantities of the component materi-
and Voids in Aggregate
als.
C31/C31M Practice for Making and Curing Concrete Test
1.2 The values stated in either SI units or inch-pound units
Specimens in the Field
are to be regarded separately as standard. The values stated in
C125 Terminology Relating to Concrete and Concrete Ag-
each system may not be exact equivalents; therefore, each
gregates
system shall be used independently of the other. Combining
C143/C143M Test Method for Slump of Hydraulic-Cement
values from the two systems may result in non-conformance
Concrete
with the standard.
C150/C150M Specification for Portland Cement
NOTE 1—Unit weight was the previous terminology used to describe the C172/C172M Practice for Sampling Freshly Mixed Con-
property determined by this test method, which is mass per unit volume.
crete
C173/C173M Test Method for Air Content of Freshly Mixed
1.3 The text of this test method refers to notes and footnotes
Concrete by the Volumetric Method
that provide explanatory material. These notes and footnotes
C188 Test Method for Density of Hydraulic Cement
(excluding those in tables and figures) shall not be considered
C231/C231M Test Method for Air Content of Freshly Mixed
as requirements of this standard.
Concrete by the Pressure Method
1.4 This standard does not purport to address all of the
C1758/C1758M Practice for Fabricating Test Specimens
safety concerns, if any, associated with its use. It is the
with Self-Consolidating Concrete
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
3. Terminology
mine the applicability of regulatory limitations prior to
3.1 Definitions—For definitions of terms used in this
use.(Warning—Fresh hydraulic cementitious mixtures are
standard, refer to Terminology C125.
caustic and may cause chemical burns to skin and tissue upon
prolonged exposure. )
3.2 Symbols:
1.5 This international standard was developed in accor-
A = air content (percentage of voids) in the concrete
dance with internationally recognized principles on standard-
3 3
C = actual cement content, kg/m [lb/yd ]
ization established in the Decision on Principles for the
C = mass of cement in the batch, kg [lb]
b
Development of International Standards, Guides and Recom-
3 3
D = density (unit weight) of concrete, kg/m [lb/ft ]
M = total mass of all materials batched, kg [lb] (see Note 3)
This test method is under the jurisdiction of ASTM Committee C09 on
M = mass of the measure filled with concrete, kg [lb] or
c
Concrete and Concrete Aggregates and is the direct responsibility of Subcommittee
C09.60 on Testing Fresh Concrete.
Current edition approved Aug. 1, 2023. Published August 2023. Originally
approved in 1938. Last previous edition approved in 2017 as C138/C138M – 17a. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
DOI: 10.1520/C0138_C0138M-23. contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
See section on Safety Precautions, Manual of Aggregate and Concrete Testing, Standards volume information, refer to the standard’s Document Summary page on
Annual Book of ASTM Standards, Vol 04.02. the ASTM website.
*A Summary 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 − 23
TABLE 1 Capacity of Measures
M = mass of the measure, kg [lb]
m
Nominal Maximum Size of Coarse
R = relative yield A
y
Capacity of Measure
Aggregate
T = theoretical density of the concrete computed on an
3 3
mm [in.] L [ft ]
airfree basis, kg/m [lb/ft ] (see Note 2)
25.0 [1] 6 [0.2]
Y = yield, volume of concrete produced per batch, m
37.5 [1 ⁄2 ] 11 [0.4]
[yd ]
50 [2] 14 [0.5]
Y = volume of concrete which the batch was designed to
75 [3] 28 [1.0]
d
3 3
112 [4 ⁄2 ] 70 [2.5]
produce, m [yd ]
3 3 150 [6] 100 [3.5]
Y = volume of concrete produced per batch, m [ft ]
f
A
The indicated size of measure shall be used to test concrete containing
V = total absolute volume of the component ingredients in
aggregates of a nominal maximum size equal to or smaller than that listed. The
3 3
the batch, m [ft ]
actual volume of the measure shall be at least 95 % of the nominal volume listed.
3 3
V = volume of the measure, m [ft ]
m
NOTE 2—The theoretical density is, customarily, a laboratory
determination, the value for which is assumed to remain constant for all
batches made using identical component ingredients and proportions.
NOTE 3—The total mass of all materials batched is the sum of the
The top rim of the air meter bowls shall be smooth and plane
masses of the cement, the fine aggregate in the condition used, the coarse
within 0.01 in. [0.3 mm] (see Note 6).
aggregate in the condition used, the mixing water added to the batch, and
any other solid or liquid materials used.
NOTE 5—The metal should not be readily subject to attack by cement
paste. However, reactive materials such as aluminum alloys may be used
4. Apparatus
in instances where as a consequence of an initial reaction, a surface film
is rapidly formed which protects the metal against further corrosion.
4.1 Balance—A balance or scale accurate to 45 g [0.1 lb] or
NOTE 6—The top rim is satisfactorily plane if a 0.3-mm [0.01-in.] feeler
to within 0.3 % of the test load, whichever is greater, at any
gage cannot be inserted between the rim and a piece of 6-mm [ ⁄4-in.] or
point within the range of use. The range of use shall be
thicker plate glass laid over the top of the measure.
considered to extend from the mass of the measure empty to
4.5 Strike-Off Plate—A flat rectangular metal plate at least 6
the mass of the measure plus its contents at 2600 kg/m [160
1 1
mm [ ⁄4 in.] thick or a glass or acrylic plate at least 12 mm [ ⁄2
lb/ft ].
in.] thick with a length and width at least 50 mm [2 in.] greater
4.2 Tamping Rod—A round, smooth, straight steel rod, with
than the diameter of the measure with which it is to be used.
5 1
a 16 mm [ ⁄8 in.] 6 2 mm [ ⁄16 in.] diameter. The length of the
The edges of the plate shall be straight and smooth within a
tamping rod shall be at least 100 mm [4 in.] greater than the
tolerance of 2 mm [ ⁄16 in.].
depth of the measure in which rodding is being performed, but
4.6 Mallet—A mallet (with a rubber or rawhide head)
not greater than 600 mm [24 in.] in overall length (see Note 4).
having a mass of 600 6 200 g [1.25 6 0.50 lb] for use with
The rod shall have the tamping end or both ends rounded to a
measures of 14 L [0.5 ft ] or smaller, and a mallet having a
hemispherical tip of the same diameter as the rod.
mass of 1000 6 200 g [2.25 6 0.50 lb] for use with measures
NOTE 4—A rod length of 400 mm [16 in.] to 600 mm [24 in.] meets the
larger than 14 L [0.5 ft ].
requirements of the following: Practice C31/C31M, Test Method C138/
C138M, Test Method C143/C143M, Test Method C173/C173M and Test
4.7 Scoop—of a size large enough so each amount of
Method C231/C231M.
concrete obtained from the sampling receptacle is representa-
4.3 Internal Vibrator—The vibrator frequency shall be at
tive and small enough so it is not spilled during placement in
least 9000 vibrations per minute [150 Hz] while the vibrator is
the measure.
operating in the concrete. The outside diameter or the side
dimension of the vibrating element shall be at least 19 mm 5. Sample
[0.75 in.] and not greater than 38 mm [1.50 in.]. The combined
5.1 Obtain the sample of freshly mixed concrete in accor-
length of the vibrator shaft and vibrating element shall exceed
dance with Practice C172/C172M.
the depth of the section being vibrated by at least 75 mm [3
in.]. The vibrator frequency shall be checked with a vibrating
6. Procedure
reed tachometer at an interval not to exceed two years. If the
6.1 Dampen the interior of the measure and remove any
vibrator manufacturer recommends a shorter verification
standing water from the bottom. Determine the mass of the
interval, a verification procedure, or other verification device,
empty measure to an accuracy consistent with the requirements
the manufacturer’s recommendation shall be followed.
of 4.1. Place the measure on a flat, level, firm surface.
4.4 Measure—A cylindrical container made of steel or other
6.2 If self-consolidating concrete is being tested, follow the
suitable metal (see Note 5). The minimum capacity of the
procedures in Practice C1758/C1758M for filling the measure.
measure shall conform to the requirements of Table 1 based on
Upon completion of the filling process, proceed to Strike-Off
the nominal size of aggregate in the concrete to be tested. All
(6.8).
measures, except for measuring bowls of air meters which are
also used for Test Method C138/C138M tests, shall conform to
NOTE 7—Practice C1758/C1758M covers the procedure for filling the
specimen container in one layer and without using any additional
the requirements of Test Method C29/C29M. When measuring
consolidation method.
bowls of air meters are used, they shall conform to the
requirements of Test Method C231/C231M, and shall be 6.3 Base the selection of the method of consolidation on the
calibrated for volume as described in Test Method C29/C29M. slump, unless the method is stated in the specifications under
C138/C138M − 23
which the work is being performed. The methods of consoli- 6.8 Strike-Off—After consolidation, strike-off the top sur-
dation are rodding and internal vibration. Rod concretes with a face of the concrete and finish it smoothly using the flat
slump greater than 75 mm [3 in.]. Rod or vibrate concrete with strike-off plate so that the measure is level full. Strike-off the
a slump of 25 to 75 mm [1 to 3 in.]. Consolidate concretes with measure by pressing the strike-off plate on the top surface of
a slump less than 25 mm [1 in.] by vibration. the measure to cover about two thirds of the surface and
withdraw the plate with a sawing motion to finish only the area
NOTE 8—Nonplastic concrete, such as is commonly used in the
originally covered. Then place the plate on the top of the
manufacture of pipe and unit masonry, is not covered by this test method.
measure to cover the original two thirds of the surface and
6.4 Place the concrete in the measure using the scoop
advance it with a vertical pressure and a sawing motion to
described in 4.7. Move the scoop around the perimeter of the
cover the whole surface of the measure and continue to
measure opening to ensure an even distribution of the concrete
advance it until it slides completely off the measure. Incline the
with minimal segregation. Fill the measure in the number of
plate and perform final strokes with the edge of the plate to
layers required by the consolidation method (6.5 or 6.6).
produce a smooth surface.
6.5 Rodding—Place the concrete in the measure in three
6.9 Cleaning and Weighing—After strike-off, clean all ex-
layers of approximately equal volume. Rod each layer with 25
cess concrete from the exterior of the measure and determine
strokes of the tamping rod when nominal 14-L [0.5-ft ] or
the mass of the concrete and measure to an accuracy consistent
smaller measures are used, 50 strokes when nominal 28-L
3 2 2
with the requirements of 4.1.
[1-ft ] measures are used, and one stroke per 20 cm [3 in. ] of
surface for larger measures. Rod each layer uniformly over the
7. Calculation
cross section with the rounded end of the rod using the required
number of strokes. Rod the bottom layer throughout its depth.
7.1 Density (Unit Weight)—Calculate the net mass of the
In rodding this layer, use care not to damage the bottom of the
concrete in pounds or kilograms by subtracting the mass of the
measure. For each upper layer, allow the rod to penetrate
measure, M , from the mass of the measure filled with
m
3 3
through the layer being rodded and into the layer below
concrete, M . Calculate the density, D, kg/m [lb/ft ] , by
c
approximately 25 mm [1 in.]. After each layer is rodded, tap
dividing the net mass of concrete by the volume of the
the sides of the measure 10 to 15 times with the appropriate
measure, V as follows:
m
mallet (see 4.6) using such force so as to close any voids left
D 5 ~M 2 M ! / V (1)
c m m
by the tamping rod and to release any large bubbles of air that
7.2 Theoretical Density—Calculate the theoretical density
may ha
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: C138/C138M − 17a C138/C138M − 23 American Association State
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 C138/C138M; 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 (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope*
1.1 This test method covers determination of the density (see Note 1) 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 SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the
two systems may result in non-conformance with the standard.
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 refers to notes and footnotes that provide explanatory information.material. These notes
and footnotes (excluding those in tables) tables and figures) shall not be considered as requirements of this test method.standard.
1.4 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 healthsafety, health, and environmental practices and determine
the applicability of regulatory limitations prior to use.(Warning—Fresh hydraulic cementitious mixtures are caustic and may
cause chemical burns to skin and tissue upon prolonged exposure. )
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
C29/C29M Test Method for Bulk Density (“Unit Weight”) and Voids in Aggregate
C31/C31M Practice for Making and Curing Concrete Test Specimens in the Field
C125 Terminology Relating to Concrete and Concrete Aggregates
This test method is under the jurisdiction of ASTM Committee C09 on Concrete and Concrete Aggregates and is the direct responsibility of Subcommittee C09.60 on
Testing Fresh Concrete.
Current edition approved March 15, 2017Aug. 1, 2023. Published May 2017August 2023. Originally approved in 1938. Last previous edition approved in 2017 as
C138/C138M – 17.C138/C138M – 17a. DOI: 10.1520/C0138_C0138M-17A.10.1520/C0138_C0138M-23.
See section on Safety Precautions, Manual of Aggregate and Concrete Testing, Annual Book of ASTM Standards, Vol 04.02.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary 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 − 23
C143/C143M Test Method for Slump of Hydraulic-Cement Concrete
C150/C150M Specification for Portland Cement
C172/C172M Practice for Sampling Freshly Mixed Concrete
C173/C173M Test Method for Air Content of Freshly Mixed Concrete by the Volumetric Method
C188 Test Method for Density of Hydraulic Cement
C231/C231M Test Method for Air Content of Freshly Mixed Concrete by the Pressure Method
C1758/C1758M Practice for Fabricating Test Specimens with Self-Consolidating Concrete
3. Terminology
3.1 Definitions—For definitions of terms used in this standard, refer to Terminology C125.
3.2 Symbols:
A = air content (percentage of voids) in the concrete
3 3
C = actual cement content, kg/m [lb/yd ]
C = mass of cement in the batch, kg [lb]
b
3 3
D = density (unit weight) of concrete, kg/m [lb/ft ]
M = total mass of all materials batched, kg [lb] (see Note 3)
M = mass of the measure filled with concrete, kg [lb] or
c
M = mass of the measure, kg [lb]
m
R = relative yield
y
3 3
T = theoretical density of the concrete computed on an airfree basis, kg/m [lb/ft ] (see Note 2)
3 3
Y = yield, volume of concrete produced per batch, m [yd ]
3 3
Y = volume of concrete which the batch was designed to produce, m [yd ]
d
3 3
Y = volume of concrete produced per batch, m [ft ]
f
3 3
V = total absolute volume of the component ingredients in the batch, m [ft ]
3 3
V = volume of the measure, m [ft ]
m
NOTE 2—The theoretical density is, customarily, a laboratory determination, the value for which is assumed to remain constant for all batches made using
identical component ingredients and proportions.
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 any other solid or liquid materials used.
4. Apparatus
4.1 Balance—A balance or scale accurate to 45 g [0.1 lb] or 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 considered to extend from the mass of the measure empty to the mass of the
3 3
measure plus its contents at 2600 kg/m [160 lb/ft ].
5 1
4.2 Tamping Rod—A round, smooth, straight steel rod, with a 16 mm [ ⁄8 in.] 6 2 mm [ ⁄16 in.] diameter. The length of the tamping
rod shall be at least 100 mm [4 in.] greater than the depth of the measure in which rodding is being performed, but not greater
than 600 mm [24 in.] in overall length (see Note 4). The rod shall have the tamping end or both ends rounded to a hemispherical
tip of the same diameter as the rod.
NOTE 4—A rod length of 400 mm [16 in.] to 600 mm [24 in.] meets the requirements of the following: Practice C31/C31M, Test Method C138/C138M,
Test Method C143/C143M, Test Method C173/C173M and Test Method C231/C231M.
4.3 Internal Vibrator—The vibrator frequency shall be at least 9000 vibrations per minute [150 Hz] while the vibrator is operating
in the concrete. The outside diameter or the side dimension of the vibrating element shall be at least 19 mm [0.75 in.] and not
greater than 38 mm [1.50 in.]. The combined length of the vibrator shaft and vibrating element shall exceed the depth of the section
being vibrated by at least 75 mm [3 in.]. The vibrator frequency shall be checked with a vibrating reed tachometer at an interval
not to exceed two years. If the vibrator manufacturer recommends a shorter verification interval, a verification procedure, or other
verification device, the manufacturer’s recommendation shall be followed.
4.4 Measure—A cylindrical container made of steel or other suitable metal (see Note 5). The minimum capacity of the measure
shall conform to the requirements of Table 1 based on the nominal size of aggregate in the concrete to be tested. All measures,
except for measuring bowls of air meters which are also used for Test Method C138/C138M tests, shall conform to the
C138/C138M − 23
TABLE 1 Capacity of Measures
Nominal Maximum Size of Coarse
A
Capacity of Measure
Aggregate
mm [in.] L [ft ]
25.0 [1] 6 [0.2]
37.5 [1 ⁄2 ] 11 [0.4]
50 [2] 14 [0.5]
75 [3] 28 [1.0]
112 [4 ⁄2 ] 70 [2.5]
150 [6] 100 [3.5]
A
The indicated size of measure shall be used to test concrete containing
aggregates of a nominal maximum size equal to or smaller than that listed. The
actual volume of the measure shall be at least 95 % of the nominal volume listed.
requirements of Test Method C29/C29M. When measuring bowls of air meters are used, they shall conform to the requirements
of Test Method C231/C231M, and shall be calibrated for volume as described in Test Method C29/C29M. The top rim of the air
meter bowls shall be smooth and plane within 0.01 in. [0.3 mm] (see Note 6).
NOTE 5—The metal should not be readily subject to attack by cement paste. However, reactive materials such as aluminum alloys may be used in instances
where as a consequence of an initial reaction, a surface film is rapidly formed which protects the metal against further corrosion.
NOTE 6—The top rim is satisfactorily plane if a 0.3-mm [0.01-in.] feeler gage cannot be inserted between the rim and a piece of 6-mm [ ⁄4-in.] or thicker
plate glass laid over the top of the measure.
1 1
4.5 Strike-Off Plate—A flat rectangular metal plate at least 6 mm [ ⁄4 in.] thick or a glass or acrylic plate at least 12 mm [ ⁄2 in.]
thick with a length and width at least 50 mm [2 in.] greater than the diameter of the measure with which it is to be used. The edges
of the plate shall be straight and smooth within a tolerance of 2 mm [ ⁄16 in.].
4.6 Mallet—A mallet (with a rubber or rawhide head) having a mass of 600 6 200 g [1.25 6 0.50 lb] for use with measures of
14 L [0.5 ft ] or smaller, and a mallet having a mass of 1000 6 200 g [2.25 6 0.50 lb] for use with measures larger than 14 L
[0.5 ft ].
4.7 Scoop—of a size large enough so each amount of concrete obtained from the sampling receptacle is representative and small
enough so it is not spilled during placement in the measure.
5. Sample
5.1 Obtain the sample of freshly mixed concrete in accordance with Practice C172/C172M.
6. Procedure
6.1 Dampen the interior of the measure and remove any standing water from the bottom. Determine the mass of the empty measure
to an accuracy consistent with the requirements of 4.1. Place the measure on a flat, level, firm surface.
6.2 If self-consolidating concrete is being tested, follow the procedures in Practice C1758/C1758M for filling the measure. Upon
completion of the filling process, proceed to Strike-Off (6.8).
NOTE 7—Practice C1758/C1758M covers the procedure for filling the specimen container in one layer and without using any additional consolidation
method.
6.3 Base the selection of the method of consolidation on the slump, unless the method is stated in the specifications under which
the work is being performed. The methods of consolidation are rodding and internal vibration. Rod concretes with a slump greater
than 75 mm [3 in.]. Rod or vibrate concrete with a slump of 25 to 75 mm [1 to 3 in.]. Consolidate concretes with a slump less
than 25 mm [1 in.] by vibration.
NOTE 8—Nonplastic concrete, such as is commonly used in the manufacture of pipe and unit masonry, is not covered by this test method.
C138/C138M − 23
6.4 Dampen the interior of the measure and remove any standing water from the bottom. Determine the mass of the empty measure
to an accuracy consistent with the requirements of 4.1. Place the measure on a flat, level, firm surface. Place the Place the concrete
in the measure using the scoop described in 4.7. Move the scoop around the perimeter of the measure opening to ensure an even
distribution of the concrete with minimal segregation. Fill the measure in the number of layers required by the consolidation
method (6.36.5 or 6.46.6).
6.2.1 Follow the procedures in Practice C1758/C1758M for filling the measure, if self-consolidating concrete is being tested. Upon
completion of the filling process, proceed to 6.6.
6.5 Rodding—Place the concrete in the measure in three layers of approximately equal volume. Rod each layer with 25 strokes
3 3
of the tamping rod when nominal 14-L [0.5-ft ] or smaller measures are used, 50 strokes when nominal 28-L [1-ft ] measures
2 2
are used, and one stroke per 20 cm [3 in. ] of surface for larger measures. Rod each layer uniformly over the cross section with
the rounded end of the rod using the required number of strokes. Rod the bottom layer throughout its depth. In rodding this layer,
use care not to damage the bottom of the measure. For each upper layer, allow the rod to penetrate through the layer being rodded
and into the layer below approximately 25 mm [1 in.]. After each layer 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 voids left by the tamping rod and to release any large bubbles
of air that may have been trapped. Add the final layer so as to avoid overfilling.
6.6 Internal Vibration—Fill and vibrate the measure in two approximately equal layers. Place all of the concrete for each layer
in the measure before starting vibration of that layer. Insert the vibrator at three different points for each layer. In compacting the
bottom layer, do not allow the vibrator to rest on or touch the bottom or sides of the measure. In compacting the final layer, the
vibrator shall penetrate into the underlying layer approximately 25 mm [1 in.] . Take care that the vibrator is withdrawn in such
a manner that no air pockets are left in the specimen. The duration of vibration required will depend upon the workability of the
concrete and the effectiveness of the vibrator (see Note 89). Continue vibration only long enough to achieve proper consolidation
of the concrete (see Note 910). Observe a constant duration of vibration for the particular kind of concrete, vibrator, and measure
involved.
NOTE 9—Usually, sufficient vibration has been applied as soon as the surface of the concrete bec
...