ASTM C94/C94M-24a

Standard Specification for Ready-Mixed Concrete

ABSTRACT
This specification covers ready-mixed concrete manufactured and delivered to a purchaser in freshly mixed and unhardened state as hereinafter specified. Requirements for quality of concrete shall be either as hereinafter specified or as specified by the purchase. In any case where the requirements of the purchaser differ from these in this specification, the purchaser's specification shall govern. In the absence of designated applicable materials specifications, materials specifications specified shall be used for cementitious materials, hydraulic cement, supplementary cementitious materials, cementitious concrete mixtures, aggregates, air-entraining admixtures, and chemical admixtures. Except as otherwise specifically permitted, cement, aggregate, and admixtures shall be measured by mass. Mixers will be stationary mixers or truck mixers. Agitators will be truck mixers or truck agitators. Test methods for compression, air content, slump, temperature shall be performed. For s strength test, at least two standard test specimens shall be made.
SCOPE
1.1 This specification covers ready-mixed concrete as defined in 3.2.2 (Note 1). Requirements for quality of ready-mixed concrete shall be either as stated in this specification or as ordered by the purchaser. When the purchaser’s requirements, as stated in the order, differ from those in this specification, the purchaser’s requirements shall govern. This specification does not cover the placement, consolidation, curing, or protection of the concrete after delivery to the purchaser.
Note 1: Concrete produced by volumetric batching and continuous mixing is covered in Specification C685/C685M. Fiber-reinforced concrete is covered in Specification C1116/C1116M.  
1.2 As used throughout this specification the producer manufactures ready-mixed concrete and the purchaser buys ready-mixed concrete.  
1.3 The values stated in either SI units, shown in brackets, 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.  
1.4 The text of this specification references notes and footnotes that provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the specification.  
1.5 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 use.2)  
1.6 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-Mar-2024
• ICS: 91.100.30 - Concrete and concrete products
• Technical Committee: C09 - Concrete and Concrete Aggregates
• Drafting Committee: C09.40 - Ready-Mixed Concrete

Relations

• Replaces: ASTM C94/C94M-24 - Standard Specification for Ready-Mixed Concrete
• Effective Date: 01-Apr-2024
• Refers: ASTM C31/C31M-24a - Standard Practice for Making and Curing Concrete Test Specimens in the Field
• Effective Date: 01-Apr-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 C1064/C1064M-23 - Standard Test Method for Temperature of Freshly Mixed Hydraulic-Cement Concrete
• Effective Date: 01-Dec-2023
• Refers: ASTM C31/C31M-23 - Standard Practice for Making and Curing Concrete Test Specimens in the Field
• Effective Date: 01-Jun-2023
• Refers: ASTM C231/C231M-22 - Standard Test Method for Air Content of Freshly Mixed Concrete by the Pressure Method
• Effective Date: 01-Jun-2022
• Refers: ASTM C39/C39M-21 - Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens
• Effective Date: 01-Mar-2021
• Refers: ASTM C1064/C1064M-17 - Standard Test Method for Temperature of Freshly Mixed Hydraulic-Cement Concrete
• Effective Date: 01-Oct-2017
• Refers: ASTM C173/C173M-16 - Standard Test Method for Air Content of Freshly Mixed Concrete by the Volumetric Method
• Effective Date: 01-Feb-2016
• Referred By: ASTM C125-21a - Standard Terminology Relating to Concrete and Concrete Aggregates
• Effective Date: 01-Apr-2024
• Referred By: ASTM C1613-24 - Standard Specification for Precast Concrete Gravity Grease Interceptor Tanks
• Effective Date: 01-Apr-2024
• Referred By: ASTM C935-19 - Standard Specification for General Requirements for Prestressed Concrete Poles Statically Cast
• Effective Date: 01-Apr-2024
• Referred By: ASTM C858-19 - Standard Specification for Underground Precast Concrete Utility Structures
• Effective Date: 01-Apr-2024
• Referred By: ASTM F1668-16(2022) - Standard Guide for Construction Procedures for Buried Plastic Pipe
• Effective Date: 01-Apr-2024
• Referred By: ASTM C1776/C1776M-17(2022) - Standard Specification for Wet-Cast Precast Modular Retaining Wall Units
• Effective Date: 01-Apr-2024

Overview

ASTM C94/C94M-24a: Standard Specification for Ready-Mixed Concrete establishes guidelines for the manufacture and delivery of ready-mixed concrete in a freshly mixed and unhardened state. Issued by ASTM International, this standard provides comprehensive requirements for the quality, ordering, and materials used in ready-mixed concrete, ensuring reliable performance in construction projects. ASTM C94/C94M-24a supersedes previous editions and remains the reference specification for ready-mixed concrete manufacturers and purchasers globally.

Key Topics

• Scope and Applicability: Covers ready-mixed concrete that is batched and delivered fresh to site. Does not include requirements for placement, curing, or protection after delivery.
• Purchaser Requirements: Purchaser specifications, if differing from those in the standard, take precedence, enhancing flexibility for project needs.
• Material Specifications: Sets baseline requirements for cementitious materials, aggregates, water, and admixtures, referencing relevant ASTM specifications.
• Mixing and Delivery: Outlines acceptable mixers (stationary or truck mixers) and agitators and details procedures for measuring and mixing materials.
• Quality Control: Specifies required test methods such as compressive strength, air content, slump, and temperature to ensure concrete meets performance and durability targets.
• Ordering Information: Standardizes details to be provided upon order, such as aggregate size, desired slump or air content, exposure conditions, and delivery requirements.

Applications

Ready-mixed concrete compliant with ASTM C94/C94M-24a is widely utilized in:

• Commercial and residential construction: Ensures consistency and reliability for foundations, slabs, walls, and structural elements.
• Infrastructure projects: Bridges, pavements, and water-retaining structures benefit from uniform quality and controlled delivery.
• Specialty uses: Specifications for lightweight, heavyweight, and air-entrained concrete address applications such as structural fill, radiation shielding, and freeze-thaw exposure.

The standard provides options for responsibility in proportion selection (Options A, B, or C) to fit various project scenarios. Both producers and purchasers are guided on materials criteria, batching accuracy, and process controls, supporting efficient, high-quality construction.

Related Standards

Several other ASTM and industry standards are referenced or aligned with ASTM C94/C94M-24a, including:

• ASTM C31/C31M: Making and curing concrete test specimens in the field
• ASTM C33/C33M: Specification for concrete aggregates
• ASTM C39/C39M: Test method for compressive strength of cylindrical concrete specimens
• ASTM C125: Terminology relating to concrete and concrete aggregates
• ASTM C138/C138M: Density (unit weight), yield, and air content of concrete
• ASTM C143/C143M: Slump of hydraulic-cement concrete
• ASTM C260/C260M, C494/C494M: Specifications for air-entraining and chemical admixtures
• ASTM C685/C685M: Specification for concrete made by volumetric batching and continuous mixing
• ASTM C1116/C1116M: Specification for fiber-reinforced concrete

These related standards provide targeted requirements for materials, testing, and specialty concrete types, ensuring comprehensive coverage across diverse construction needs.

Practical Value

Contractors, engineers, and material suppliers turn to ASTM C94/C94M-24a for its robust framework promoting quality, consistency, and performance in ready-mixed concrete. By adhering to this specification, stakeholders benefit from:

• Standardized product quality and traceability
• Clear communication of project-specific requirements
• Confidence in regulatory and safety compliance
• Optimized material utilization and cost control

ASTM C94/C94M-24a plays a central role in ensuring that ready-mixed concrete is fit for purpose, supporting safe, durable, and successful construction outcomes worldwide.

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: C94/C94M − 24a
Standard Specification for
Ready-Mixed Concrete
This standard is issued under the fixed designation C94/C94M; 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* (Warning—Fresh hydraulic cementitious mixtures are caustic
and may cause chemical burns to skin and tissue upon
1.1 This specification covers ready-mixed concrete as de-
prolonged use. )
fined in 3.2.2 (Note 1). Requirements for quality of ready-
1.6 This international standard was developed in accor-
mixed concrete shall be either as stated in this specification or
dance with internationally recognized principles on standard-
as ordered by the purchaser. When the purchaser’s
ization established in the Decision on Principles for the
requirements, as stated in the order, differ from those in this
Development of International Standards, Guides and Recom-
specification, the purchaser’s requirements shall govern. This
mendations issued by the World Trade Organization Technical
specification does not cover the placement, consolidation,
Barriers to Trade (TBT) Committee.
curing, or protection of the concrete after delivery to the
purchaser.
2. Referenced Documents
NOTE 1—Concrete produced by volumetric batching and continuous
2.1 ASTM Standards:
mixing is covered in Specification C685/C685M. Fiber-reinforced con-
C31/C31M Practice for Making and Curing Concrete Test
crete is covered in Specification C1116/C1116M.
Specimens in the Field
1.2 As used throughout this specification the producer
C33/C33M Specification for Concrete Aggregates
manufactures ready-mixed concrete and the purchaser buys
C39/C39M Test Method for Compressive Strength of Cylin-
ready-mixed concrete.
drical Concrete Specimens
C125 Terminology Relating to Concrete and Concrete Ag-
1.3 The values stated in either SI units, shown in brackets,
gregates
or inch-pound units are to be regarded separately as standard.
C138/C138M Test Method for Density (Unit Weight), Yield,
The values stated in each system may not be exact equivalents;
and Air Content (Gravimetric) of Concrete
therefore, each system shall be used independently of the other.
C143/C143M Test Method for Slump of Hydraulic-Cement
Combining values from the two systems may result in non-
Concrete
conformance with the standard.
C150/C150M Specification for Portland Cement
1.4 The text of this specification references notes and
C172/C172M Practice for Sampling Freshly Mixed Con-
footnotes that provide explanatory material. These notes and
crete
footnotes (excluding those in tables and figures) shall not be
C173/C173M Test Method for Air Content of Freshly Mixed
considered as requirements of the specification.
Concrete by the Volumetric Method
1.5 This standard does not purport to address all of the
C231/C231M Test Method for Air Content of Freshly Mixed
safety concerns, if any, associated with its use. It is the
Concrete by the Pressure Method
responsibility of the user of this standard to establish appro-
C260/C260M Specification for Air-Entraining Admixtures
priate safety, health, and environmental practices and deter-
for Concrete
mine the applicability of regulatory limitations prior to use.
C330/C330M Specification for Lightweight Aggregates for
Structural Concrete
1 2
This specification is under the jurisdiction of ASTM Committee C09 on See Section on Safety Precautions, Manual of Aggregate and Concrete Testing,
Concrete and Concrete Aggregates and is the direct responsibility of Subcommittee Annual Book of ASTM Standards, Vol 04.02.
C09.40 on Ready-Mixed Concrete. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved April 1, 2024. Published April 2024. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1933. Last previous edition approved in 2024 as C94/C94M – 24. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/C0094_C0094M-24A.
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
C94/C94M − 24a
C494/C494M Specification for Chemical Admixtures for 2.3 Other Documents:
Concrete NIST 105-1 National Institute of Standards and Technology
Handbook
C567/C567M Test Method for Determining Density of
Structural Lightweight Concrete
3. Terminology
C595/C595M Specification for Blended Hydraulic Cements
3.1 Definitions—The terms used in this specification are
C618 Specification for Coal Ash and Raw or Calcined
defined in Terminology C125.
Natural Pozzolan for Use in Concrete
3.2 Definitions of Terms Specific to This Standard:
C637 Specification for Aggregates for Radiation-Shielding
3.2.1 concrete, central-mixed, n—ready-mixed concrete
Concrete
mixed completely in a stationary mixer.
C685/C685M Specification for Concrete Made by Volumet-
ric Batching and Continuous Mixing 3.2.2 concrete, ready-mixed, n—concrete manufactured and
C979/C979M Specification for Pigments for Integrally Col- delivered to a purchaser in a fresh state.
ored Concrete
3.2.3 concrete, shrink-mixed, n—ready-mixed concrete par-
C989/C989M Specification for Slag Cement for Use in
tially mixed in a stationary mixer with mixing completed in a
Concrete and Mortars
truck mixer.
C1064/C1064M Test Method for Temperature of Freshly
3.2.4 concrete, truck-mixed, n—ready-mixed concrete com-
Mixed Hydraulic-Cement Concrete
pletely mixed in a truck mixer.
C1077 Practice for Agencies Testing Concrete and Concrete
3.2.5 water, target batch, n—quantity of water to be added
Aggregates for Use in Construction and Criteria for
to the batch through the water measuring system after com-
Testing Agency Evaluation
pensating for the quantity of ice, if used, surface moisture on
C1116/C1116M Specification for Fiber-Reinforced Concrete
the aggregates and water in the admixtures, when applicable,
C1157/C1157M Performance Specification for Hydraulic
and by subtracting a quantity of water that is anticipated to be
Cement
added at the job site or in transit to adjust slump or slump flow
C1240 Specification for Silica Fume Used in Cementitious
of the concrete batch.
Mixtures
4. Basis of Purchase
C1582/C1582M Specification for Admixtures to Inhibit
Chloride-Induced Corrosion of Reinforcing Steel in Con- 4.1 The basis of purchase shall be a cubic yard or cubic
meter of fresh concrete as discharged from the transportation
crete
unit.
C1602/C1602M Specification for Mixing Water Used in the
Production of Hydraulic Cement Concrete
4.2 The volume of fresh concrete in a given batch shall be
C1611/C1611M Test Method for Slump Flow of Self-
determined from the total mass of the batch divided by the
Consolidating Concrete
density of the concrete. The total mass of the batch shall be
C1697 Specification for Blended Supplementary Cementi-
determined as the net mass of the concrete in the batch as
tious Materials delivered, including the total mixing water as defined in 9.4.
The density shall be determined in accordance with Test
C1797 Specification for Ground Calcium Carbonate and
Method C138/C138M. The yield shall be determined as the
Aggregate Mineral Fillers for use in Hydraulic Cement
average of at least three measurements, one from each of three
Concrete
different transportation units sampled in accordance with
C1798/C1798M Specification for Returned Fresh Concrete
Practice C172/C172M.
for Use in a New Batch of Ready-Mixed Concrete
C1866/C1866M Specification for Ground-Glass Pozzolan
NOTE 2—It should be understood that the volume of hardened concrete
may be, or appear to be, less than expected due to waste and spillage,
for Use in Concrete
over-excavation, spreading forms, some loss of entrained air, or settlement
2.2 ACI Documents:
of wet mixtures, none of which is the responsibility of the producer.
ACI 211.1 Standard Practice for Selecting Proportions for
5. Materials
Normal, Heavyweight, and Mass Concrete
ACI 211.2 Standard Practice for Selecting Proportions for 5.1 In the absence of designated applicable material
specifications, the following material specifications shall be
Structural Lightweight Concrete
used:
ACI 301 Standard Specifications for Structural Concrete
ACI 305.1 Specification for Hot Weather Concreting
5.2 Cementitious Materials:
ACI 305R Guide to Hot Weather Concreting
5.2.1 Hydraulic Cement—Hydraulic cement shall conform
ACI 306R Guide to Cold Weather Concreting
to Specification C150/C150M, Specification C595/C595M, or
ACI 318 Building Code Requirements for Structural Con-
Specification C1157/C1157M.
crete and Commentary
NIST Handbook 105-1 (revised 1990), “Specifications and Tolerances for
Reference Standards and Field Standard Weights and Measures-1. Specifications
and Tolerances for Field Standard Weights (NIST Class F),” National Institute of
Available from American Concrete Institute (ACI), P.O. Box 9094, Farmington Standards and Technology., U.S. Dept. of Commerce, http://www.nist.gov/pml/
Hills, MI 48333-9094, http://www.concrete.org. wmd/upload/105-1.pdf.
C94/C94M − 24a
5.2.2 Supplementary Cementitious Materials—Coal ash or 6.1.3 Slump flow, or flows, desired at the point of discharge
natural pozzolans shall conform to Specification C618. Slag from the transportation unit (see Section 7 for acceptable
cement shall conform to Specification C989/C989M. Silica tolerances),
fume shall conform to Specification C1240. Ground-glass 6.1.4 Total air content at the point of discharge from the
pozzolan shall conform to Specification C1866/C1866M. transportation unit for concrete that will be exposed to cycles
Blended supplementary cementitious materials shall conform of freezing and thawing or anticipated exposure of the concrete
to Specification C1697. (see Section 8 for sampling for air content tests and tolerances).
NOTE 3—Specification C1697 does not apply to the combination of NOTE 7—Table 1 provides total air contents for concrete that vary by
individually batched supplementary cementitious materials during the
exposure condition and aggregate size. Total air contents less than those
production of ready-mixed concrete. shown in Table 1 may be specified or used for concrete that is not subject
to freezing and thawing. This may be done to improve workability and
5.3 Aggregates—Normal weight aggregates shall conform
cohesiveness, reduce the rate of bleeding, reduce the water content for a
to Specification C33/C33M. Lightweight aggregates shall con-
given consistency, or achieve required lightweight concrete density.
form to Specification C330/C330M and heavyweight aggre-
Specified total air contents higher than those shown in Table 1 may reduce
strength without any further improvement of durability.
gates shall conform to Specification C637.
Exposure conditions for freezing and thawing environments in Table 1
5.4 Ground Calcium Carbonate and Aggregate Mineral
correspond to the following:
Filler—Ground calcium carbonate and aggregate mineral filler
Moderate Exposure—Concrete exposed to freeze-thaw cycles but not
in contact with the ground or with limited exposure to water, limiting the
shall conform to Specification C1797.
ability to cause saturation of a portion of the concrete prior to freezing.
5.5 Water—Water shall conform to Specification C1602/
The concrete shall not receive deicing salts or other aggressive chemicals.
C1602M. Examples include: exterior beams, columns, walls, girders, footings below
the frost line, or elevated slabs where application of deicing salt is not
5.6 Admixtures—Chemical admixtures shall conform to
anticipated. The air content requirements for this exposure are consistent
Specification C494/C494M. Air-entraining admixtures shall
with those for Exposure Class F1 of ACI 318.
conform to Specification C260/C260M. Admixtures to inhibit Severe Exposure—Concrete exposed to freeze-thaw cycles while in
contact with the ground or with frequent exposure to water, potentially
chloride induced corrosion of reinforcing steel in concrete shall
causing saturation of a portion of the concrete prior to freezing. The
conform to Specification C1582/C1582M. Pigments for inte-
concrete may receive deicing chemicals or other aggressive chemicals.
grally colored concrete shall conform to Specification C979/
Examples include: pavements, bridge decks, curbs, gutters, sidewalks,
C979M.
canal linings, or exterior water tanks or sumps. The air content require-
NOTE 4—In any given instance, the required dosage of air-entraining, ments for this exposure are consistent with those for Exposure Classes F2
accelerating, retarding, water-reducing, and high-range water-reducing and F3 of ACI 318.
admixtures may vary. Therefore, a range of dosages should be allowed,
6.1.5 Which of Options A, B, or C shall be used as a basis
which will permit obtaining the desired effect.
for determining the proportions of the concrete to produce the
NOTE 5—Interchanging kinds, characteristics, types, classes, or grades
of the materials permitted in ready-mixed concrete may produce concrete required quality,
of different properties.
6.1.6 When lightweight concrete is specified, the equilib-
rium density,
5.7 Returned Fresh Concrete—Returned fresh concrete,
when permitted by the purchaser, shall conform to Specifica-
NOTE 8—The density of fresh concrete is the only measurable density
tion C1798/C1798M.
of lightweight concrete at the time of delivery. The density of fresh
concrete is always higher than the equilibrium or oven-dry density.
NOTE 6—Specification C1798/C1798M provides requirements for
Therefore, for acceptance of lightweight concrete based on density at the
using, measuring, and reporting returned fresh concrete. These require-
point of discharge from the transportation unit, a relationship between the
ments are in addition to those stated herein. The purchaser may further
equilibrium density and density of fresh concrete needs to be established.
clarify which concrete within an order, such as specific mixtures or
Definitions of, and methods for determining or calculating equilibrium
applications, may incorporate returned fresh concrete.
and oven-dry density, are covered by Test Method C567/C567M.
6. Ordering Information 6.1.7 When high-density or heavyweight concrete is
specified, the density of fresh concrete, and
6.1 In the absence of designated applicable general
specifications, the purchaser’s order shall include the follow-
NOTE 9—High-density or heavyweight concrete typically contains
aggregate with a relative density of 3.3 or greater conforming to
ing:
Specification C637. This concrete is used for radiation shielding or other
6.1.1 Designated size, or sizes, of coarse aggregate,
applications where higher density is required by design. For acceptance of
6.1.2 Slump, or slumps, desired at the point of discharge
density at point of discharge from the transportation unit, a relationship
from the transportation unit (see Section 7 for acceptable
between the fresh density and the density of hardened concrete required by
tolerances), design should be established.
TABLE 1 Total Air Content for Air-Entrained Concrete Exposed to Cycles of Freezing and Thawing
Total Air Content, %
Exposure Nominal Maximum Sizes of Aggregate, mm [in.]
3 1 3 1
Condition 9.5 [ ⁄8 ] 12.5 [ ⁄2 ] 19.0 [ ⁄4 ] 25.0 [1] 37.5 [1 ⁄2 ] 50.0 [2] 75.0 [3]
(See Note 7)
Moderate 6.0 5.5 5.0 4.5 4.5 4.0 3.5
Severe 7.5 7.0 6.0 6.0 5.5 5.0 4.5
C94/C94M − 24a
6.1.8 If desired, any of the optional requirements of Table 2 production of each class of concrete ordered by the purchaser.
in Specification C1602/C1602M. The producer shall also furnish evidence satisfactory to the
purchaser that the materials to be used and proportions selected
6.1.9 Purchaser shall state any drum revolution limit as to
will produce concrete of the quality specified.
when the concrete discharge must begin. If no drum revolution
limit is stated by purchaser, the producer shall determine and
6.5 Option B:
communicate the limit to the purchaser prior to delivery.
6.5.1 When the purchaser assumes responsibility for the
6.1.10 Purchaser shall state a time limit from the start of
proportioning of the concrete mixture, he shall also specify the
mixing defined in 12.3 or 12.5 to when the concrete discharge
following:
must be completed. If no time limit is stated by purchaser, the
6.5.1.1 Cement content in kilograms per cubic meter
producer shall establish and communicate the limit to the
[pounds per cubic yard] of concrete,
purchaser prior to delivery. The time limit to complete dis-
6.5.1.2 Maximum allowable water content in liters per cubic
charge shall be stated on the delivery ticket in accordance with
meter [gallons per cubic yard] of concrete, including surface
14.1.14.
moisture on the aggregates, but excluding water of absorption
(Note 11), and
NOTE 10—This specification previously included a 1 ⁄2 h time limit to
end of discharge since its original publication in 1935. There are many
6.5.1.3 If admixtures are required, the type, name, and
options available to the producer to provide the required quality of
dosage to be used. The cement content shall not be reduced
1 1
concrete with end of discharge limits beyond 1 ⁄2 h or less than 1 ⁄2 h. The
when admixtures are used under this option without the written
purchaser should consult with the producer for available options to
approval of the purchaser.
establish a time limit to end of discharge prior to or at the time concrete
is ordered. Selection of a time limit to end of discharge should consider 6.5.2 At the request of the purchaser, the producer shall,
ambient conditions, types of cementitious materials and admixtures used,
prior to the actual delivery of the concrete, furnish a statement
placement procedures, and projected transportation time between the
to the purchaser giving the sources, densities, and sieve
batch plant and the point of delivery.
analyses of the aggregates and the dry masses of cement and
6.2 If a project specification applies, the order shall include
saturated-surface-dry masses of fine and coarse aggregate and
applicable requirements for the concrete to be produced in
quantities, type and name of admixture (if any) and of water
compliance with the specification.
per cubic yard or cubic meter of concrete that will be used in
the production of each class of concrete ordered by the
6.3 If the type, kind, or class of cementitious materials in
purchaser.
5.2.1 and 5.2.2 are not designated by the purchaser, it is
permitted to use cementitious materials in concrete mixtures
6.6 Option C:
that will satisfy the concrete properties and other requirements
6.6.1 When the purchaser requires the producer to assume
of the purchaser as ordered.
responsibility for the selection of the proportions for the
concrete mixture with the minimum allowable cement content
6.4 Option A:
specified (Note 12), the purchaser shall also specify the
6.4.1 When the purchaser requires the producer to assume
following:
full responsibility for the selection of the proportions for the
6.6.1.1 Requirements for compressive strength as deter-
concrete mixture (Note 11), the purchaser shall also specify the
mined on samples taken from the transportation unit at the
following:
point of discharge in accordance with Section 17 and speci-
6.4.1.1 Requirements for compressive strength as deter-
mens made, cured, and tested in accordance with Section 18.
mined on samples taken from the transportation unit at the
The purchaser shall specify the requirements for strength in
point of discharge in accordance with Section 17 and speci-
terms of tests of standard specimens cured under standard
mens made, cured, and tested in accordance with Section 18.
laboratory conditions for moist curing (see Section 18). Unless
The purchaser shall specify the requirements in terms of the
otherwise specified the age at test shall be 28 days.
compressive strength of standard specimens cured under stan-
6.6.1.2 Minimum cement content in kilograms per cubic
dard laboratory conditions for moist curing (see Section 18).
meter [pounds per cubic yard] of concrete.
Unless otherwise specified the age at test shall be 28 days.
6.6.1.3 If admixtures are required, the type, name, and
NOTE 11—The purchaser, in selecting requirements for which he
dosage to be used. The cement content shall not be reduced
assumes responsibility should give consideration to requirements for
when admixtures are used.
workability, placeability, durability, surface texture, and density, in addi-
tion to those for structural design. The purchaser is referred to Standard
NOTE 12—Option C can be distinctive and useful only if the designated
Practice ACI 211.1 and Standard Practice ACI 211.2 for the selection of
minimum cement content is at about the same level that would ordinarily
proportions that will result in concrete suitable for various types of
be required for the strength, aggregate size, and slump or slump flow
structures and conditions of exposure. The water-cement ratio of most
specified. At the same time, it must be an amount that will be sufficient to
structural lightweight concretes cannot be determined with sufficient
ensure durability under expected service conditions, as well as satisfactory
accuracy for use as a specification basis.
surface texture and density, in the event specified strength is attained with
it. For additional information refer to Standard Practice ACI 211.1 and
6.4.2 At the request of the purchaser, the producer shall,
Standard Practice 211.2 referred to in Note 11.
prior to the actual delivery of the concrete, furnish a statement
to the purchaser, giving the dry masses of cement and saturated 6.6.2 At the request of the purchaser, the producer shall,
surface-dry-masses of fine and coarse aggregate and quantities, prior to the actual delivery of the concrete, furnish a statement
type, and name of admixtures (if any) and of water per cubic to the purchaser, giving the dry masses of cement and saturated
yard or cubic meter of concrete that will be used in the surface-dry masses of fine and coarse aggregate and quantities,
C94/C94M − 24a
type, and name of admixture (if any) and of water per cubic user is unprepared for discharge of the concrete from the
yard or cubic meter of concrete that will be used in the vehicle, the producer shall not be responsible for the limitation
production of each class of concrete ordered by the purchaser. of minimum slump or slump flow after 30 min have elapsed
The producer shall also furnish evidence satisfactory to the starting either on arrival of the vehicle at the prescribed
purchaser that the materials to be used and proportions selected destination or at the requested delivery time, whichever is later.
will produce concrete of the quality specified. Whatever
strengths are attained the quantity of cement used shall not be
8. Air-Entrained Concrete
less than the minimum specified.
8.1 Unless otherwise specified, for air-entrained concrete
6.7 The proportions arrived at by Options A, B, or C for
the total air contents in Table 1 shall apply based on the
each class of concrete shall be available at the batch plant and exposure condition stated in the purchase order. It is permitted
be assigned a designation to facilitate identification of each
to reduce the total air content values in Table 1 by one
concrete mixture delivered to the project. This is the designa- percentage point for concretes with a specified compressive
tion required in 14.1.7 and supplies information on concrete
strength greater than or equal to 35 MPa [5000 psi]. Total air
proportions when they are not given separately on each content that differs from the values in Table 1 is permitted for
delivery ticket as outlined in 14.2.
concrete not exposed to cycles of freezing and thawing (Note
7).
6.8 The purchaser shall ensure that the producer is provided
copies of all reports of tests performed on concrete samples
8.2 The air content of air-entrained concrete when sampled
taken to determine compliance with specification requirements.
from the transportation unit at the point of discharge shall be
Reports shall be provided on a timely basis.
within a tolerance of 61.5 of the specified value.
6.9 The producer shall obtain the purchaser’s permission to
8.3 When a preliminary sample taken within the time limits
incorporate returned fresh concrete.
of 12.7 and prior to discharge for placement shows an air
content below the specified level by more than the allowable
7. Slump or Slump Flow
tolerance in accordance with 8.2, the producer may use
additional air entraining admixture to achieve the desired air
7.1 Unless other tolerances are indicated by the purchaser,
content level, followed by a minimum of 30 revolutions at
the following shall apply.
mixing speed, so long as the revolution limit of 6.1.9 is not
7.1.1 When slump is stated as a “maximum” or “not to
exceeded (see Note 13).
exceed” requirement:
NOTE 13—Acceptance sampling and testing in accordance with Practice
Tolerances for “Maximum” or “Not to Exceed” Slumps
C172/C172M is not obviated by this provision. Increasing the air content
For Slump of: Tolerance
may increase the slump or slump flow.
75 mm [3 in.] or less +0 and –40 mm [1 ⁄2 in.]
1 9. Measuring Materials
More than 75 mm [3 in.] +0 and –65 mm [2 ⁄2 in.]
7.1.1.1 The maximum or not to exceed slump provision 9.1 Except as otherwise specifically permitted, cementitious
shall be used only if a job site water addition is permitted by materials shall be measured by mass. When supplementary
the specification in accordance with 12.7. cementitious materials are used in the concrete mixtures, the
7.1.2 When slump is stated as a target or nominal slump: cumulative mass is permitted to be measured with hydraulic
cement, but in a batch hopper and on a scale which is separate
Tolerances for Target or Nominal Slumps
and distinct from those used for other materials except for
For Slump of: Tolerance
ground calcium carbonate and aggregate mineral filler. The
mass of the hydraulic cement shall be measured before
50 mm [2 in.] and less ±15 mm [ ⁄2 in.]
More than 50 mm to 100 mm [2 in. through 4 in.] ±25 mm [1 in.]
supplementary cementitious materials. When the quantity of
More than 100 mm [4 in.] ±40 mm [1 ⁄2 in.]
cementitious material exceeds 30 % of the full capacity of the
7.1.3 When the purchaser states a slump flow requirement
scale, the measured quantity of the hydraulic cement shall be
for self-consolidating concrete:
within 61 % of the required mass, and the cumulative mea-
Tolerances for Slump Flow sured quantity of hydraulic cement plus supplementary cemen-
titious materials shall also be within 61 % of the required
For Slump Flow Tolerance
cumulative mass at each intermediate weighing. For smaller
3 3
Less than or equal to 550 mm [22 in.] ±40 mm [1 ⁄2 in.]
concrete batches to a minimum of 1 m [1 yd ], the measured
More than 550 mm [22 in. ] ±65 mm [2 ⁄2 in.]
quantity of the hydraulic cement and the measured cumulative
7.1.4 The tolerances for slump or slump flow apply to the
quantity of hydraulic cement plus supplementary cementitious
values stated in the order when adjustments in accordance with
materials used shall be not less than the required amount nor
12.7 and 12.8 are permitted. more than 4 % in excess. When the purchaser requires alternate
methods of measuring cementitious materials, measurement
7.2 Concrete shall be available within the permissible range
methods and reporting shall be stated in the order (see Note
of slump or slump flow for a period of 30 min starting either on
14).
arrival at the job site or after the initial slump adjustment
permitted in 12.7, whichever is later. The first and last ⁄4 m
NOTE 14—Cementitious materials in bags may be used when requested
[ ⁄4 yd ] discharged are exempt from this requirement. If the or permitted by the purchaser.
C94/C94M − 24a
NOTE 18—Admixture dispensers of the mechanical type capable of
9.2 Aggregate shall be measured by mass. The quantity of
adjustment for variation of dosage, and of simple calibration, are
aggregate weighed shall be the required dry mass plus the total
recommended.
moisture content (absorbed and surface) of the aggregate.
9.2.1 For individual weigh batchers, the quantity of aggre- 10. Batching Plant
gate weighed shall be within 62 % of the required mass;
10.1 Bins with adequate separate compartments shall be
except if the required quantity of aggregate is less than 15 % of
provided in the batching plant for fine and for each required
scale capacity, the quantity of aggregate weighed shall be
size of coarse aggregate. Each bin compartment shall be
within 60.3 % of scale capacity.
designed and operated so as to discharge efficiently and freely,
9.2.2 For cumulative weigh batchers, if the required quan-
with minimum segregation, into the weighing hopper. Means
tity of aggregate is equal to or greater than 30 % of the scale
of control shall be provided so that, as the quantity desired in
capacity, the quantity of aggregate weighed shall be within
the weighing hopper is approached, the material shall be shut
61 % of the required mass at each successive weighing. If the
off with precision. Weighing hoppers shall be constructed so as
required quantity of aggregate is less than 30 % of the scale
to eliminate accumulations of tare materials and to discharge
capacity, the quantity of aggregate weighed shall be within
fully.
60.3 % of scale capacity at each successive weighing.
10.2 Indicating devices shall be in full view and near
NOTE 15—The batching accuracy limit of 0.3 % of scale capacity
enough to be read accurately by the operator while charging the
establishes a reasonable minimum weighing tolerance that is independent
hopper. The operator shall have convenient access to all
of the quantity of material being weighed.
controls.
9.3 Except as otherwise specifically permitted, ground cal-
10.3 Scales shall be considered accurate if their accuracy is
cium carbonate and aggregate mineral filler shall be measured
verified through the normally used capacity in accordance with
by mass and on the same scale as the cementitious materials.
Table 2 and load indicated relative to applied test load is within
The masses of ground calcium carbonate and aggregate min-
60.15 % of the total capacity of the scale or 0.4 % of the net
eral filler shall be measured after the cementitious materials.
applied load, whichever is greater. The minimum quantity and
Each cumulative measured quantity of cementitious materials
sequence of applied test loads used to verify material scales
with ground calcium carbonate, aggregate mineral filler, or
shall conform to Table 2 and its notes.
both shall be within the cumulative mass tolerances in 9.1.
10.4 All exposed fulcrums, clevises, and similar working
When the purchaser requires alternate methods of measuring
parts of scales shall be kept clean. Beam scales shall be
ground calcium carbonate and aggregate mineral filler, mea-
equipped with a balance indicator sensitive enough to show
surement methods and reporting shall be stated in the order.
movement when a weight equal to 0.1 % of the nominal
NOTE 16—Ground calcium carbonate and aggregate mineral filler are
capacity of the scale is placed in the batch hopper. Pointer
not considered part of the cementitious materials.
travel shall be a minimum of 5 % of the net-rated capacity of
9.4 Mixing water shall consist of batch water (water
the largest weigh beam for underweight and 4 % for over-
weighed or metered at the plant), ice, free moisture on the
weight.
aggregates, wash water retained in the mixer before batching,
10.5 The device for the measurement of the added water
water added at the job site in accordance with 12.7 or by an
shall be capable of delivering to the batch the quantity required
automated truck mixer system in accordance with 12.8, and
within the accuracy required in 9.4. The device shall be so
water introduced from admixtures if the quantity added in-
arranged that the measurements will not be affected by variable
creases the water-cementitious materials ratio by more than
pressures in the water supply line. Measuring tanks shall be
0.01 (Note 17). The batch water shall be measured by mass or
equipped with outside taps and valves to provide for checking
volume to an accuracy of 61.5 % of the target batch water. Ice
their calibration unless other means are provided for readily
shall be measured by mass. In the case of truck mixers, any
and accurately determining the amount of water in the tank.
wash water retained in the drum for use in the next batch of
NOTE 19—The scale accuracy limitations of the National Ready Mixed
concrete shall be measured; if this proves impractical or
Concrete Association Plant Certification meet the requirements of this
impossible the wash water shall be discharged before loading
specification.
the next batch of concrete. Quantity of mixing water shall be
accurate to within 63 % of the amount established by the
11. Mixers and Agitators
designed mixture proportions.
11.1 Mixers include stationary mixers or truck mixers.
NOTE 17—Mixing water is the total amount of water in a batch less the Agitators include truck mixers or truck agitators.
water absorbed by the aggregates. Mixing water is used to calculate the
11.1.1 Stationary mixers shall be equipped with a metal
water-cementitious materials ratio (w/cm).
plate or plates on which are plainly marked the mixing speed
9.5 Chemical admixtures in powdered form shall be mea- of the drum or paddles, and the maximum capacity in terms of
sured by mass. Liquid chemical admixtures shall be batched by the volume of mixed concrete. If used for the complete mixing
mass or volume. Admixtures measured by either mass or of concrete, stationary mixers shall be equipped with an
volume shall be batched with an accuracy of 63 % of the total acceptable timing device that will not permit the batch to be
amount required or plus or minus the amount or dosage discharged until the specified mixing time has elapsed.
required for 50 kg [100 lb] of hydraulic cement, whichever is 11.1.2 Each truck mixer or agitator shall have attached
greater. thereto in a prominent place a metal plate or plates on which
C94/C94M − 24a
A
TABLE 2 Minimum Field Standard Weights and Test Loads
Minimum
(in terms of device capacity)
Device Capacity Minimum Loads for Verification of Scale Accuracy
Field Standard
C
Test Loads
Weights
0 kg to 2000 kg
100 % 100 %
[0 lb to 4000 lb]
B
2001 kg to 20 000 kgGreater of Field standard weights or test load to used capacity, if greater than minimum
10 % or 500 kg
[4001 lb to 40 000 lb] specified.
D
50 %
[1000 lb] E
Strain-load tests are permitted to be used above test load minimums. During initial
verification, a scale shall be tested to full capacity.
A
If the configuration and set up of the scale system prevents access or application of adequate field standard weights or if an unsafe condition is created by the verification
process then the use of the scale above the verified position shall be discontinued until corrective measures have been completed.
B
Field standard weights used in verifying accuracy of weighing devices shall comply with requirements of NIST Handbook 105-1.
C
The term “test load” means the sum of the combination of field standard weights and any other applied load used in the conduct of a test using substitution test methods.
Substitution Test—In the substitution test procedure, material or objects are substituted for field standard weights, or a combination of field standard weights and previously
quantified material or objects, using the scale under test as a comparator. Additional test weights or other known test loads may be added to the known test load to verify
the accuracy of higher weight ranges on the scale.
D
The scale shall be tested from zero to at least 10 % of scale capacity using field standard weights, and then to at least 50 % of scale capacity using a series of substitution
load tests that utilize field standard weights equaling at least 10 % of scale capacity.
E
A strain-load test shall be conducted to verify the accuracy from 50 % of scale capacity to the used capacity of the scale. At least one load test shall be performed in
each quarter of scale capacity. Strain-Load Test—In the strain-load test procedure, an unknown quantity of material or objects are used to establish a reference load or
tare to which field standard weights or substitution test loads are added.
are plainly marked the gross volume of the drum, the capacity condition due to accumulations of hardened concrete or mortar
of the drum or container in terms of the volume of mixed and examined to detect wear of blades. If these conditions are
concrete, and the minimum and maximum mixing speeds of considered extensive enough to affect the mixer performance,
rotation of the drum, blades, or paddles. If the concrete is truck Annex A1 establishes the basis to determine whether correction
mixed as described in 12.5, or shrink mixed as described in of deficiencies is required or if the correction of the deficien-
12.4, the volume of mixed concrete shall not exceed 63 % of cies is adequate.
the total volume of the drum or container. If the concrete is
central mixed as described in 12.3, the volume of concrete in 12. Mixing and Delivery
the truck mixer or agitator shall not exceed 80 % of the total
12.1 Ready-mixed concrete shall be mixed and delivered to
volume of the drum or container. Truck mixers and agitators
the point designated by the purchaser by means of one of the
shall be equipped with means to readily verify the number of
following combinations of operations:
revolutions of the drum, blades, or paddles.
12.1.1 Central-Mixed Concrete.
11.2 Stationary and truck mixers shall be capable of pro-
12.1.2 Shrink-Mixed Concrete.
ducing uniformly mixed concrete within the specified time in
12.1.3 Truck-Mixed Concrete.
12.3 or the specified number of revolutions in 12.5. The
12.2 Mixers and agitators shall be operated within the limits
capability to produce and discharge uniformly mixed concrete
shall be determined in accordance with Annex A1, if required. of capacity and speed of rotation designated by the manufac-
turer of the equipment.
NOTE 20—The sequence or method of charging the mixer will have an
important effect on the uniformity of the concrete.
12.3 Central-Mixed Concrete—Concrete that is mixed com-
11.3 The agitator shall be capable of maintaining the mixed pletely in a stationary mixer and transported to the point of
delivery either in a truck agitator, or a truck mixer operating at
concrete in a uniformly mixed condition. The capability to
maintain and discharge uniformly mixed concrete shall be agitating speed, or in non-agitating equipment approved by the
purchaser and meeting the requirements of Section 13, shall
determined in accordance with Annex A1, if required.
conform to the following: The mixing time shall be counted
11.4 Slump tests of individual samples can be used to
from the time all the solid materials are in the drum. The batch
provide a quick check of the probable degree of uniformity.
shall be so charged into the mixer that some water will enter in
Sampling and testing shall be in accordance with Annex A1. If
advance of the cement and aggregate and the target batch water
the difference in slump exceeds the limits in Annex A1, the
shall be in the drum by the end of the first one fourth of the
mixer or agitator shall not be used unless the condition is
specified mixing time; or in accordance with the central
corrected, except as provided in 11.5.
concrete mixer manufacturer’s recommended charging se-
11.5 Use of the equipment not conforming to 11.2 is
quence.
permitted if operated with a longer mixing time, a smaller load,
12.3.1 If no mixer performance tests are made, the accept-
or a more efficient charging sequence. If required, the unifor- 3
able mixing time for mixers having capacities of 0.76 m
mity of concrete shall be evaluated in accordance with Annex
[1 yd ] or less shall be not less than 1 min. For mixers of
A1.
greater capacity, this minimum shall be increased 15 s for each
11.6 Mixers and agitators shall be examined or their mass cubic meter [cubic yard] or fraction thereof of additional
determined as frequently as necessary to detect changes in capacity (see Note 21).
C94/C94M − 24a
NOTE 21—Stationary mixers of similar design bearing a Performance
maximum water content for the batch as established by the
Rating plate of the Concrete Plant Manufacturers Bureau have been tested
designed mixture proportions. Adjusting the concrete mixture
for their ability to produce uniformly mixed concrete in accordance with
with water or water-reducing admixture shall be done before
Annex A1 for low slump (<50 mm [2 in.]) and normal slump (100 mm to
discharge of concrete, except when obtaining a preliminary
150 mm [4 in. to 6 in.]) concrete in a mixing time between 30 s and 90 s.
sample in accordance with 17.6. Additional water shall be
12.3.2 If mixer performance tests have been made in accor-
injected into the mixer under pressure and direction of flow to
dance with Annex A1, the acceptable mixing time is permitted
allow for proper distribution within the mixer. After the
to be reduced to the time equal to or greater than that used in
additions, the drum shall be turned at least 30 revolutions at
the qualification testing. If the mixing time is so reduced the
mixing speed. The quantity of water or water-reducing admix-
maximum time of mixing shall not exceed this reduced time by
ture added shall be recorded.
more than 60 s for air-entrained concrete. Mixer performance
12.8 For truck mixers with automated water or water-
tests shall be repeated whenever the appearance of the concrete
reducing admixture measurement and slump or slump flow
or a comparison of coarse aggregate content of separate
monitoring equipment defined in 12.8.1 and if permitted by the
samples as described in Annex A1 indicates that adequate
purchaser, water, or water-reducing admixture, or both, may be
mixing has not been accomplished.
added during transportation to the job site. Such additional
12.4 Shrink-Mixed Concrete—Concrete that is first partially
water shall be injected into the mixer under such pressure and
mixed in a stationary mixer, and then mixed completely in a
direction of flow to allow for proper distribution within the
truck mixer, shall conform to the following: The time of partial
mixer. The water content of the batch shall not exceed that
mixing shall be the minimum time required to intermingle the
established by the designed mixture proportions. If water or
ingredients. After transfer to a truck mixer the amount of
water-reducing admixture is added, the mixer shall be turned at
mixing at the designated mixing speed shall be that necessary
least 30 drum revolutions at mixing speed. Said mixing shall
to meet the requirements for uniformity of concrete as indi-
take place after the last water or water-reducing admixture
cated in Annex A1. Additional turning of the mixer, if any,
addition but before the start of discharge. The acceptance or
shall be at a designated agitating speed.
rejection of concrete based on slump or slump flow shall be in
12.5 Truck-Mixed Concrete—Concrete that is completely
accordance with Section 17.
mixed in a truck mixer for 70 to 100 revolutions at the mixing
12.8.1 The automated slump or slump flow monitoring
speed designated by the truck mixer manufacturer shall pro-
equipment shall be capable of obtaining one or more physical
duce uniformly mixed concrete as defined in Annex A1. The
measurements on the truck mixer related to concrete slump or
start of mixing shall be when all the materials have been loaded
slump flow and providing an indication of slump or slump flow
in the mixer. If requirements for uniformity of concrete
based on pre-established correlations. The slump or slump flow
indicated in Annex A1 are not met with 100 revolutions of
measurement equipment
...

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: C94/C94M − 24 C94/C94M − 24a
Standard Specification for
Ready-Mixed Concrete
This standard is issued under the fixed designation C94/C94M; 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 specification covers ready-mixed concrete as defined in 3.2.2 (Note 1). Requirements for quality of ready-mixed concrete
shall be either as stated in this specification or as ordered by the purchaser. When the purchaser’s requirements, as stated in the
order, differ from those in this specification, the purchaser’s requirements shall govern. This specification does not cover the
placement, consolidation, curing, or protection of the concrete after delivery to the purchaser.
NOTE 1—Concrete produced by volumetric batching and continuous mixing is covered in Specification C685/C685M. Fiber-reinforced concrete is covered
in Specification C1116/C1116M.
1.2 As used throughout this specification the producer manufactures ready-mixed concrete and the purchaser buys ready-mixed
concrete.
1.3 The values stated in either SI units, shown in brackets, 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.
1.4 The text of this specification references notes and footnotes that provide explanatory material. These notes and footnotes
(excluding those in tables and figures) shall not be considered as requirements of the specification.
1.5 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 use. )
1.6 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:
This specification is under the jurisdiction of ASTM Committee C09 on Concrete and Concrete Aggregates and is the direct responsibility of Subcommittee C09.40 on
Ready-Mixed Concrete.
Current edition approved Jan. 1, 2024April 1, 2024. Published February 2024April 2024. Originally approved in 1933. Last previous edition approved in 20232024 as
C94/C94M – 23.C94/C94M – 24. DOI: 10.1520/C0094_C0094M-24.10.1520/C0094_C0094M-24A.
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
C94/C94M − 24a
C31/C31M Practice for Making and Curing Concrete Test Specimens in the Field
C33/C33M Specification for Concrete Aggregates
C39/C39M Test Method for Compressive Strength of Cylindrical Concrete Specimens
C125 Terminology Relating to Concrete and Concrete Aggregates
C138/C138M Test Method for Density (Unit Weight), Yield, and Air Content (Gravimetric) of Concrete
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
C231/C231M Test Method for Air Content of Freshly Mixed Concrete by the Pressure Method
C260/C260M Specification for Air-Entraining Admixtures for Concrete
C330/C330M Specification for Lightweight Aggregates for Structural Concrete
C494/C494M Specification for Chemical Admixtures for Concrete
C567/C567M Test Method for Determining Density of Structural Lightweight Concrete
C595/C595M Specification for Blended Hydraulic Cements
C618 Specification for Coal Ash and Raw or Calcined Natural Pozzolan for Use in Concrete
C637 Specification for Aggregates for Radiation-Shielding Concrete
C685/C685M Specification for Concrete Made by Volumetric Batching and Continuous Mixing
C979/C979M Specification for Pigments for Integrally Colored Concrete
C989/C989M Specification for Slag Cement for Use in Concrete and Mortars
C1064/C1064M Test Method for Temperature of Freshly Mixed Hydraulic-Cement Concrete
C1077 Practice for Agencies Testing Concrete and Concrete Aggregates for Use in Construction and Criteria for Testing Agency
Evaluation
C1116/C1116M Specification for Fiber-Reinforced Concrete
C1157/C1157M Performance Specification for Hydraulic Cement
C1240 Specification for Silica Fume Used in Cementitious Mixtures
C1582/C1582M Specification for Admixtures to Inhibit Chloride-Induced Corrosion of Reinforcing Steel in Concrete
C1602/C1602M Specification for Mixing Water Used in the Production of Hydraulic Cement Concrete
C1611/C1611M Test Method for Slump Flow of Self-Consolidating Concrete
C1697 Specification for Blended Supplementary Cementitious Materials
C1797 Specification for Ground Calcium Carbonate and Aggregate Mineral Fillers for use in Hydraulic Cement Concrete
C1798/C1798M Specification for Returned Fresh Concrete for Use in a New Batch of Ready-Mixed Concrete
C1866/C1866M Specification for Ground-Glass Pozzolan for Use in Concrete
2.2 ACI Documents:
ACI 211.1 Standard Practice for Selecting Proportions for Normal, Heavyweight, and Mass Concrete
ACI 211.2 Standard Practice for Selecting Proportions for Structural Lightweight Concrete
ACI 301 Standard Specifications for Structural Concrete
ACI 305.1 Specification for Hot Weather Concreting
ACI 305R Guide to Hot Weather Concreting
ACI 306R Guide to Cold Weather Concreting
ACI 318 Building Code Requirements for Structural Concrete and Commentary
2.3 Other Documents:
NIST 105-1 National Institute of Standards and Technology Handbook
3. Terminology
3.1 Definitions—The terms used in this specification are defined in Terminology C125.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 concrete, central-mixed, n—ready-mixed concrete mixed completely in a stationary mixer.
3.2.2 concrete, ready-mixed, n—concrete manufactured and delivered to a purchaser in a fresh state.
Available from American Concrete Institute (ACI), P.O. Box 9094, Farmington Hills, MI 48333-9094, http://www.concrete.org.
NIST Handbook 105-1 (revised 1990), “Specifications and Tolerances for Reference Standards and Field Standard Weights and Measures-1. Specifications and Tolerances
for Field Standard Weights (NIST Class F),” National Institute of Standards and Technology., U.S. Dept. of Commerce, http://www.nist.gov/pml/wmd/upload/105-1.pdf.
C94/C94M − 24a
3.2.3 concrete, shrink-mixed, n—ready-mixed concrete partially mixed in a stationary mixer with mixing completed in a truck
mixer.
3.2.4 concrete, truck-mixed, n—ready-mixed concrete completely mixed in a truck mixer.
3.2.5 water, target batch, n—quantity of water to be added to the batch through the water measuring system after compensating
for the quantity of ice, if used, surface moisture on the aggregates and water in the admixtures, when applicable, and by subtracting
a quantity of water that is anticipated to be added at the job site or in transit to adjust slump or slump flow of the concrete batch.
4. Basis of Purchase
4.1 The basis of purchase shall be a cubic yard or cubic meter of fresh concrete as discharged from the transportation unit.
4.2 The volume of fresh concrete in a given batch shall be determined from the total mass of the batch divided by the density of
the concrete. The total mass of the batch shall be determined as the net mass of the concrete in the batch as delivered, including
the total mixing water as defined in 9.4. The density shall be determined in accordance with Test Method C138/C138M. The yield
shall be determined as the average of at least three measurements, one from each of three different transportation units sampled
in accordance with Practice C172/C172M.
NOTE 2—It should be understood that the volume of hardened concrete may be, or appear to be, less than expected due to waste and spillage,
over-excavation, spreading forms, some loss of entrained air, or settlement of wet mixtures, none of which is the responsibility of the producer.
5. Materials
5.1 In the absence of designated applicable material specifications, the following material specifications shall be used:
5.2 Cementitious Materials:
5.2.1 Hydraulic Cement—Hydraulic cement shall conform to Specification C150/C150M, Specification C595/C595M, or
Specification C1157/C1157M.
5.2.2 Supplementary Cementitious Materials—Coal ash or natural pozzolans shall conform to Specification C618. Slag cement
shall conform to Specification C989/C989M. Silica fume shall conform to Specification C1240. Ground-glass pozzolan shall
conform to Specification C1866/C1866M. Blended supplementary cementitious materials shall conform to Specification C1697.
NOTE 3—Specification C1697 does not apply to the combination of individually batched supplementary cementitious materials during the production of
ready-mixed concrete.
5.3 Aggregates—Normal weight aggregates shall conform to Specification C33/C33M. Lightweight aggregates shall conform to
Specification C330/C330M and heavyweight aggregates shall conform to Specification C637.
5.4 Ground Calcium Carbonate and Aggregate Mineral Filler—Ground calcium carbonate and aggregate mineral filler shall
conform to Specification C1797.
5.5 Water—Water shall conform to Specification C1602/C1602M.
5.6 Admixtures—Chemical admixtures shall conform to Specification C494/C494M. Air-entraining admixtures shall conform to
Specification C260/C260M. Admixtures to inhibit chloride induced corrosion of reinforcing steel in concrete shall conform to
Specification C1582/C1582M. Pigments for integrally colored concrete shall conform to Specification C979/C979M.
NOTE 4—In any given instance, the required dosage of air-entraining, accelerating, retarding, water-reducing, and high-range water-reducing admixtures
may vary. Therefore, a range of dosages should be allowed, which will permit obtaining the desired effect.
NOTE 5—Interchanging kinds, characteristics, types, classes, or grades of the materials permitted in ready-mixed concrete may produce concrete of
different properties.
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5.7 Returned Fresh Concrete—Returned fresh concrete, when permitted by the purchaser, shall conform to Specification
C1798/C1798M.
NOTE 6—Specification C1798/C1798M provides requirements for using, measuring, and reporting returned fresh concrete. These requirements are in
addition to those stated herein. The purchaser may further clarify which concrete within an order, such as specific mixtures or applications, may
incorporate returned fresh concrete.
6. Ordering Information
6.1 In the absence of designated applicable general specifications, the purchaser’s order shall include the following:
6.1.1 Designated size, or sizes, of coarse aggregate,
6.1.2 Slump, or slumps, desired at the point of discharge from the transportation unit (see Section 7 for acceptable tolerances),
6.1.3 Slump flow, or flows, desired at the point of discharge from the transportation unit (see Section 7 for acceptable tolerances),
6.1.4 Total air content at the point of discharge from the transportation unit for concrete that will be exposed to cycles of freezing
and thawing or anticipated exposure of the concrete (see Section 8 for sampling for air content tests and tolerances).
NOTE 7—Table 1 provides total air contents for concrete that vary by exposure condition and aggregate size. Total air contents less than those shown in
Table 1 may be specified or used for concrete that is not subject to freezing and thawing. This may be done to improve workability and cohesiveness,
reduce the rate of bleeding, reduce the water content for a given consistency, or achieve required lightweight concrete density. Specified total air contents
higher than those shown in Table 1 may reduce strength without any further improvement of durability.
Exposure conditions for freezing and thawing environments in Table 1 correspond to the following:
Moderate Exposure—Concrete exposed to freeze-thaw cycles but not in contact with the ground or with limited exposure to water, limiting the ability
to cause saturation of a portion of the concrete prior to freezing. The concrete shall not receive deicing salts or other aggressive chemicals. Examples
include: exterior beams, columns, walls, girders, footings below the frost line, or elevated slabs where application of deicing salt is not anticipated. The
air content requirements for this exposure are consistent with those for Exposure Class F1 of ACI 318.
Severe Exposure—Concrete exposed to freeze-thaw cycles while in contact with the ground or with frequent exposure to water, potentially causing
saturation of a portion of the concrete prior to freezing. The concrete may receive deicing chemicals or other aggressive chemicals. Examples include:
pavements, bridge decks, curbs, gutters, sidewalks, canal linings, or exterior water tanks or sumps. The air content requirements for this exposure are
consistent with those for Exposure Classes F2 and F3 of ACI 318.
6.1.5 Which of Options A, B, or C shall be used as a basis for determining the proportions of the concrete to produce the required
quality,
6.1.6 When lightweight concrete is specified, the equilibrium density,
NOTE 8—The density of fresh concrete is the only measurable density of lightweight concrete at the time of delivery. The density of fresh concrete is
always higher than the equilibrium or oven-dry density. Therefore, for acceptance of lightweight concrete based on density at the point of discharge from
the transportation unit, a relationship between the equilibrium density and density of fresh concrete needs to be established. Definitions of, and methods
for determining or calculating equilibrium and oven-dry density, are covered by Test Method C567/C567M.
6.1.7 When high-density or heavyweight concrete is specified, the density of fresh concrete, and
NOTE 9—High-density or heavyweight concrete typically contains aggregate with a relative density of 3.3 or greater conforming to Specification C637.
This concrete is used for radiation shielding or other applications where higher density is required by design. For acceptance of density at point of
discharge from the transportation unit, a relationship between the fresh density and the density of hardened concrete required by design should be
established.
TABLE 1 Total Air Content for Air-Entrained Concrete Exposed to Cycles of Freezing and Thawing
Total Air Content, %
Exposure Nominal Maximum Sizes of Aggregate, mm [in.]
3 1 3 1
Condition 9.5 [ ⁄8 ] 12.5 [ ⁄2 ] 19.0 [ ⁄4 ] 25.0 [1] 37.5 [1 ⁄2 ] 50.0 [2] 75.0 [3]
(See Note 7)
Moderate 6.0 5.5 5.0 4.5 4.5 4.0 3.5
Severe 7.5 7.0 6.0 6.0 5.5 5.0 4.5
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6.1.8 If desired, any of the optional requirements of Table 2 in Specification C1602/C1602M.
6.1.9 Purchaser shall state any drum revolution limit as to when the concrete discharge must begin. If no drum revolution limit
is stated by purchaser, the producer shall determine and communicate the limit to the purchaser prior to delivery.
6.1.10 Purchaser shall state a time limit from the start of mixing defined in 12.3 or 12.5 to when the concrete discharge must be
completed. If no time limit is stated by purchaser, the producer shall establish and communicate the limit to the purchaser prior
to delivery. The time limit to complete discharge shall be stated on the delivery ticket in accordance with 14.1.14.
NOTE 10—This specification previously included a 1 ⁄2 h time limit to end of discharge since its original publication in 1935. There are many options
1 1
available to the producer to provide the required quality of concrete with end of discharge limits beyond 1 ⁄2 h or less than 1 ⁄2 h. The purchaser should
consult with the producer for available options to establish a time limit to end of discharge prior to or at the time concrete is ordered. Selection of a time
limit to end of discharge should consider ambient conditions, types of cementitious materials and admixtures used, placement procedures, and projected
transportation time between the batch plant and the point of delivery.
6.2 If a project specification applies, the order shall include applicable requirements for the concrete to be produced in compliance
with the specification.
6.3 If the type, kind, or class of cementitious materials in 5.2.1 and 5.2.2 are not designated by the purchaser, it is permitted to
use cementitious materials in concrete mixtures that will satisfy the concrete properties and other requirements of the purchaser
as ordered.
6.4 Option A:
6.4.1 When the purchaser requires the producer to assume full responsibility for the selection of the proportions for the concrete
mixture (Note 11), the purchaser shall also specify the following:
6.4.1.1 Requirements for compressive strength as determined on samples taken from the transportation unit at the point of
discharge in accordance with Section 17 and specimens made, cured, and tested in accordance with Section 18. The purchaser shall
specify the requirements in terms of the compressive strength of standard specimens cured under standard laboratory conditions
for moist curing (see Section 18). Unless otherwise specified the age at test shall be 28 days.
NOTE 11—The purchaser, in selecting requirements for which he assumes responsibility should give consideration to requirements for workability,
placeability, durability, surface texture, and density, in addition to those for structural design. The purchaser is referred to Standard Practice ACI 211.1
and Standard Practice ACI 211.2 for the selection of proportions that will result in concrete suitable for various types of structures and conditions of
exposure. The water-cement ratio of most structural lightweight concretes cannot be determined with sufficient accuracy for use as a specification basis.
6.4.2 At the request of the purchaser, the producer shall, prior to the actual delivery of the concrete, furnish a statement to the
purchaser, giving the dry masses of cement and saturated surface-dry-masses of fine and coarse aggregate and quantities, type, and
name of admixtures (if any) and of water per cubic yard or cubic meter of concrete that will be used in the production of each class
of concrete ordered by the purchaser. The producer shall also furnish evidence satisfactory to the purchaser that the materials to
be used and proportions selected will produce concrete of the quality specified.
6.5 Option B:
6.5.1 When the purchaser assumes responsibility for the proportioning of the concrete mixture, he shall also specify the following:
6.5.1.1 Cement content in kilograms per cubic meter [pounds per cubic yard] of concrete,
6.5.1.2 Maximum allowable water content in liters per cubic meter [gallons per cubic yard] of concrete, including surface moisture
on the aggregates, but excluding water of absorption (Note 11), and
6.5.1.3 If admixtures are required, the type, name, and dosage to be used. The cement content shall not be reduced when
admixtures are used under this option without the written approval of the purchaser.
6.5.2 At the request of the purchaser, the producer shall, prior to the actual delivery of the concrete, furnish a statement to the
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purchaser giving the sources, densities, and sieve analyses of the aggregates and the dry masses of cement and saturated-surface-
dry masses of fine and coarse aggregate and quantities, type and name of admixture (if any) and of water per cubic yard or cubic
meter of concrete that will be used in the production of each class of concrete ordered by the purchaser.
6.6 Option C:
6.6.1 When the purchaser requires the producer to assume responsibility for the selection of the proportions for the concrete
mixture with the minimum allowable cement content specified (Note 12), the purchaser shall also specify the following:
6.6.1.1 Requirements for compressive strength as determined on samples taken from the transportation unit at the point of
discharge in accordance with Section 17 and specimens made, cured, and tested in accordance with Section 18. The purchaser shall
specify the requirements for strength in terms of tests of standard specimens cured under standard laboratory conditions for moist
curing (see Section 18). Unless otherwise specified the age at test shall be 28 days.
6.6.1.2 Minimum cement content in kilograms per cubic meter [pounds per cubic yard] of concrete.
6.6.1.3 If admixtures are required, the type, name, and dosage to be used. The cement content shall not be reduced when
admixtures are used.
NOTE 12—Option C can be distinctive and useful only if the designated minimum cement content is at about the same level that would ordinarily be
required for the strength, aggregate size, and slump or slump flow specified. At the same time, it must be an amount that will be sufficient to ensure
durability under expected service conditions, as well as satisfactory surface texture and density, in the event specified strength is attained with it. For
additional information refer to Standard Practice ACI 211.1 and Standard Practice 211.2 referred to in Note 11.
6.6.2 At the request of the purchaser, the producer shall, prior to the actual delivery of the concrete, furnish a statement to the
purchaser, giving the dry masses of cement and saturated surface-dry masses of fine and coarse aggregate and quantities, type, and
name of admixture (if any) and of water per cubic yard or cubic meter of concrete that will be used in the production of each class
of concrete ordered by the purchaser. The producer shall also furnish evidence satisfactory to the purchaser that the materials to
be used and proportions selected will produce concrete of the quality specified. Whatever strengths are attained the quantity of
cement used shall not be less than the minimum specified.
6.7 The proportions arrived at by Options A, B, or C for each class of concrete and approved for use in a project shallshall be
available at the batch plant and be assigned a designation to facilitate identification of each concrete mixture delivered to the
project. This is the designation required in 14.1.7 and supplies information on concrete proportions when they are not given
separately on each delivery ticket as outlined in 14.2. A certified copy of all proportions as established in Options A, B, or C shall
be on file at the batch plant.
6.8 The purchaser shall ensure that the producer is provided copies of all reports of tests performed on concrete samples taken
to determine compliance with specification requirements. Reports shall be provided on a timely basis.
6.9 The producer shall obtain the purchaser’s permission to incorporate returned fresh concrete.
7. Slump or Slump Flow
7.1 Unless other tolerances are indicated by the purchaser, the following shall apply.
7.1.1 When slump is stated as a “maximum” or “not to exceed” requirement:
Tolerances for “Maximum” or “Not to Exceed” Slumps
For Slump of: Tolerance
75 mm [3 in.] or less +0 and –40 mm [1 ⁄2 in.]
More than 75 mm [3 in.] +0 and –65 mm [2 ⁄2 in.]
7.1.1.1 The maximum or not to exceed slump provision shall be used only if a job site water addition is permitted by the
specification in accordance with 12.7.
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7.1.2 When slump is stated as a target or nominal slump:
Tolerances for Target or Nominal Slumps
For Slump of: Tolerance
50 mm [2 in.] and less ±15 mm [ ⁄2 in.]
More than 50 mm to 100 mm [2 in. through 4 in.] ±25 mm [1 in.]
More than 100 mm [4 in.] ±40 mm [1 ⁄2 in.]
7.1.3 When the purchaser states a slump flow requirement for self-consolidating concrete:
Tolerances for Slump Flow
For Slump Flow Tolerance
Less than or equal to 550 mm [22 in.] ±40 mm [1 ⁄2 in.]
More than 550 mm [22 in. ] ±65 mm [2 ⁄2 in.]
7.1.4 The tolerances for slump or slump flow apply to the values stated in the order when adjustments in accordance with 12.7
and 12.8 are permitted.
7.2 Concrete shall be available within the permissible range of slump or slump flow for a period of 30 min starting either on arrival
3 3
1 1
at the job site or after the initial slump adjustment permitted in 12.7, whichever is later. The first and last ⁄4 m [ ⁄4 yd ] discharged
are exempt from this requirement. If the user is unprepared for discharge of the concrete from the vehicle, the producer shall not
be responsible for the limitation of minimum slump or slump flow after 30 min have elapsed starting either on arrival of the vehicle
at the prescribed destination or at the requested delivery time, whichever is later.
8. Air-Entrained Concrete
8.1 Unless otherwise specified, for air-entrained concrete the total air contents in Table 1 shall apply based on the exposure
condition stated in the purchase order. It is permitted to reduce the total air content values in Table 1 by one percentage point for
concretes with a specified compressive strength greater than or equal to 35 MPa [5000 psi]. Total air content that differs from the
values in Table 1 is permitted for concrete not exposed to cycles of freezing and thawing (Note 7).
8.2 The air content of air-entrained concrete when sampled from the transportation unit at the point of discharge shall be within
a tolerance of 61.5 of the specified value.
8.3 When a preliminary sample taken within the time limits of 12.7 and prior to discharge for placement shows an air content
below the specified level by more than the allowable tolerance in accordance with 8.2, the producer may use additional air
entraining admixture to achieve the desired air content level, followed by a minimum of 30 revolutions at mixing speed, so long
as the revolution limit of 6.1.9 is not exceeded (see Note 13).
NOTE 13—Acceptance sampling and testing in accordance with Practice C172/C172M is not obviated by this provision. Increasing the air content may
increase the slump or slump flow.
9. Measuring Materials
9.1 Except as otherwise specifically permitted, cementitious materials shall be measured by mass. When supplementary
cementitious materials are used in the concrete mixtures, the cumulative mass is permitted to be measured with hydraulic cement,
but in a batch hopper and on a scale which is separate and distinct from those used for other materials except for ground calcium
carbonate and aggregate mineral filler. The mass of the hydraulic cement shall be measured before supplementary cementitious
materials. When the quantity of cementitious material exceeds 30 % of the full capacity of the scale, the measured quantity of the
hydraulic cement shall be within 61 % of the required mass, and the cumulative measured quantity of hydraulic cement plus
supplementary cementitious materials shall also be within 61 % of the required cumulative mass at each intermediate weighing.
3 3
For smaller concrete batches to a minimum of 1 m [1 yd ], the measured quantity of the hydraulic cement and the measured
cumulative quantity of hydraulic cement plus supplementary cementitious materials used shall be not less than the required amount
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nor more than 4 % in excess. When the purchaser requires alternate methods of measuring cementitious materials, measurement
methods and reporting shall be stated in the order (see Note 14).
NOTE 14—Cementitious materials in bags may be used when requested or permitted by the purchaser.
9.2 Aggregate shall be measured by mass. The quantity of aggregate weighed shall be the required dry mass plus the total moisture
content (absorbed and surface) of the aggregate.
9.2.1 For individual weigh batchers, the quantity of aggregate weighed shall be within 62 % of the required mass; except if the
required quantity of aggregate is less than 15 % of scale capacity, the quantity of aggregate weighed shall be within 60.3 % of
scale capacity.
9.2.2 For cumulative weigh batchers, if the required quantity of aggregate is equal to or greater than 30 % of the scale capacity,
the quantity of aggregate weighed shall be within 61 % of the required mass at each successive weighing. If the required quantity
of aggregate is less than 30 % of the scale capacity, the quantity of aggregate weighed shall be within 60.3 % of scale capacity
at each successive weighing.
NOTE 15—The batching accuracy limit of 0.3 % of scale capacity establishes a reasonable minimum weighing tolerance that is independent of the quantity
of material being weighed.
9.3 Except as otherwise specifically permitted, ground calcium carbonate and aggregate mineral filler shall be measured by mass
and on the same scale as the cementitious materials. The masses of ground calcium carbonate and aggregate mineral filler shall
be measured after the cementitious materials. Each cumulative measured quantity of cementitious materials with ground calcium
carbonate, aggregate mineral filler, or both shall be within the cumulative mass tolerances in 9.1. When the purchaser requires
alternate methods of measuring ground calcium carbonate and aggregate mineral filler, measurement methods and reporting shall
be stated in the order.
NOTE 16—Ground calcium carbonate and aggregate mineral filler are not considered part of the cementitious materials.
9.4 Mixing water shall consist of batch water (water weighed or metered at the plant), ice, free moisture on the aggregates, wash
water retained in the mixer before batching, water added at the job site in accordance with 12.7 or by an automated truck mixer
system in accordance with 12.8, and water introduced from admixtures if the quantity added increases the water-cementitious
materials ratio by more than 0.01 (Note 17). The batch water shall be measured by mass or volume to an accuracy of 61.5 % of
the target batch water. Ice shall be measured by mass. In the case of truck mixers, any wash water retained in the drum for use
in the next batch of concrete shall be measured; if this proves impractical or impossible the wash water shall be discharged before
loading the next batch of concrete. Quantity of mixing water shall be accurate to within 63 % of the amount established by the
designed mixture proportions.
NOTE 17—Mixing water is the total amount of water in a batch less the water absorbed by the aggregates. Mixing water is used to calculate the
water-cementitious materials ratio (w/cm).
9.5 Chemical admixtures in powdered form shall be measured by mass. Liquid chemical admixtures shall be batched by mass or
volume. Admixtures measured by either mass or volume shall be batched with an accuracy of 63 % of the total amount required
or plus or minus the amount or dosage required for 50 kg [100 lb] of hydraulic cement, whichever is greater.
NOTE 18—Admixture dispensers of the mechanical type capable of adjustment for variation of dosage, and of simple calibration, are recommended.
10. Batching Plant
10.1 Bins with adequate separate compartments shall be provided in the batching plant for fine and for each required size of coarse
aggregate. Each bin compartment shall be designed and operated so as to discharge efficiently and freely, with minimum
segregation, into the weighing hopper. Means of control shall be provided so that, as the quantity desired in the weighing hopper
is approached, the material shall be shut off with precision. Weighing hoppers shall be constructed so as to eliminate accumulations
of tare materials and to discharge fully.
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10.2 Indicating devices shall be in full view and near enough to be read accurately by the operator while charging the hopper. The
operator shall have convenient access to all controls.
10.3 Scales shall be considered accurate if their accuracy is verified through the normally used capacity in accordance with Table
2 and load indicated relative to applied test load is within 60.15 % of the total capacity of the scale or 0.4 % of the net applied
load, whichever is greater. The minimum quantity and sequence of applied test loads used to verify material scales shall conform
to Table 2 and its notes.
10.4 All exposed fulcrums, clevises, and similar working parts of scales shall be kept clean. Beam scales shall be equipped with
a balance indicator sensitive enough to show movement when a weight equal to 0.1 % of the nominal capacity of the scale is placed
in the batch hopper. Pointer travel shall be a minimum of 5 % of the net-rated capacity of the largest weigh beam for underweight
and 4 % for overweight.
10.5 The device for the measurement of the added water shall be capable of delivering to the batch the quantity required within
the accuracy required in 9.4. The device shall be so arranged that the measurements will not be affected by variable pressures in
the water supply line. Measuring tanks shall be equipped with outside taps and valves to provide for checking their calibration
unless other means are provided for readily and accurately determining the amount of water in the tank.
NOTE 19—The scale accuracy limitations of the National Ready Mixed Concrete Association Plant Certification meet the requirements of this
specification.
11. Mixers and Agitators
11.1 Mixers include stationary mixers or truck mixers. Agitators include truck mixers or truck agitators.
11.1.1 Stationary mixers shall be equipped with a metal plate or plates on which are plainly marked the mixing speed of the drum
or paddles, and the maximum capacity in terms of the volume of mixed concrete. If used for the complete mixing of concrete,
stationary mixers shall be equipped with an acceptable timing device that will not permit the batch to be discharged until the
specified mixing time has elapsed.
11.1.2 Each truck mixer or agitator shall have attached thereto in a prominent place a metal plate or plates on which are plainly
marked the gross volume of the drum, the capacity of the drum or container in terms of the volume of mixed concrete, and the
minimum and maximum mixing speeds of rotation of the drum, blades, or paddles. If the concrete is truck mixed as described in
12.5, or shrink mixed as described in 12.4, the volume of mixed concrete shall not exceed 63 % of the total volume of the drum
or container. If the concrete is central mixed as described in 12.3, the volume of concrete in the truck mixer or agitator shall not
A
TABLE 2 Minimum Field Standard Weights and Test Loads
Minimum
(in terms of device capacity)
Device Capacity Minimum Loads for Verification of Scale Accuracy
Field Standard
C
Test Loads
Weights
0 kg to 2000 kg
100 % 100 %
[0 lb to 4000 lb]
B
2001 kg to 20 000 kgGreater of Field standard weights or test load to used capacity, if greater than minimum
10 % or 500 kg
[4001 lb to 40 000 lb] specified.
D
50 %
[1000 lb] E
Strain-load tests are permitted to be used above test load minimums. During initial
verification, a scale shall be tested to full capacity.
A
If the configuration and set up of the scale system prevents access or application of adequate field standard weights or if an unsafe condition is created by the verification
process then the use of the scale above the verified position shall be discontinued until corrective measures have been completed.
B
Field standard weights used in verifying accuracy of weighing devices shall comply with requirements of NIST Handbook 105-1.
C
The term “test load” means the sum of the combination of field standard weights and any other applied load used in the conduct of a test using substitution test methods.
Substitution Test—In the substitution test procedure, material or objects are substituted for field standard weights, or a combination of field standard weights and previously
quantified material or objects, using the scale under test as a comparator. Additional test weights or other known test loads may be added to the known test load to verify
the accuracy of higher weight ranges on the scale.
D
The scale shall be tested from zero to at least 10 % of scale capacity using field standard weights, and then to at least 50 % of scale capacity using a series of substitution
load tests that utilize field standard weights equaling at least 10 % of scale capacity.
E
A strain-load test shall be conducted to verify the accuracy from 50 % of scale capacity to the used capacity of the scale. At least one load test shall be performed in
each quarter of scale capacity. Strain-Load Test—In the strain-load test procedure, an unknown quantity of material or objects are used to establish a reference load or
tare to which field standard weights or substitution test loads are added.
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exceed 80 % of the total volume of the drum or container. Truck mixers and agitators shall be equipped with means to readily verify
the number of revolutions of the drum, blades, or paddles.
11.2 Stationary and truck mixers shall be capable of producing uniformly mixed concrete within the specified time in 12.3 or the
specified number of revolutions in 12.5. The capability to produce and discharge uniformly mixed concrete shall be determined
in accordance with Annex A1, if required.
NOTE 20—The sequence or method of charging the mixer will have an important effect on the uniformity of the concrete.
11.3 The agitator shall be capable of maintaining the mixed concrete in a uniformly mixed condition. The capability to maintain
and discharge uniformly mixed concrete shall be determined in accordance with Annex A1, if required.
11.4 Slump tests of individual samples can be used to provide a quick check of the probable degree of uniformity. Sampling and
testing shall be in accordance with Annex A1. If the difference in slump exceeds the limits in Annex A1, the mixer or agitator shall
not be used unless the condition is corrected, except as provided in 11.5.
11.5 Use of the equipment not conforming to 11.2 is permitted if operated with a longer mixing time, a smaller load, or a more
efficient charging sequence. If required, the uniformity of concrete shall be evaluated in accordance with Annex A1.
11.6 Mixers and agitators shall be examined or their mass determined as frequently as necessary to detect changes in condition
due to accumulations of hardened concrete or mortar and examined to detect wear of blades. If these conditions are considered
extensive enough to affect the mixer performance, Annex A1 establishes the basis to determine whether correction of deficiencies
is required or if the correction of the deficiencies is adequate.
12. Mixing and Delivery
12.1 Ready-mixed concrete shall be mixed and delivered to the point designated by the purchaser by means of one of the following
combinations of operations:
12.1.1 Central-Mixed Concrete.
12.1.2 Shrink-Mixed Concrete.
12.1.3 Truck-Mixed Concrete.
12.2 Mixers and agitators shall be operated within the limits of capacity and speed of rotation designated by the manufacturer of
the equipment.
12.3 Central-Mixed Concrete—Concrete that is mixed completely in a stationary mixer and transported to the point of delivery
either in a truck agitator, or a truck mixer operating at agitating speed, or in non-agitating equipment approved by the purchaser
and meeting the requirements of Section 13, shall conform to the following: The mixing time shall be counted from the time all
the solid materials are in the drum. The batch shall be so charged into the mixer that some water will enter in advance of the cement
and aggregate and the target batch water shall be in the drum by the end of the first one fourth of the specified mixing time; or
in accordance with the central concrete mixer manufacturer’s recommended charging sequence.
3 3
12.3.1 If no mixer performance tests are made, the acceptable mixing time for mixers having capacities of 0.76 m [1 yd ] or less
shall be not less than 1 min. For mixers of greater capacity, this minimum shall be increased 15 s for each cubic meter [cubic yard]
or fraction thereof of additional capacity (see Note 21).
NOTE 21—Stationary mixers of similar design bearing a Performance Rating plate of the Concrete Plant Manufacturers Bureau have been tested for their
ability to produce uniformly mixed concrete in accordance with Annex A1 for low slump (<50 mm [2 in.]) and normal slump (100 mm to 150 mm [4 in.
to 6 in.]) concrete in a mixing time between 30 s and 90 s.
12.3.2 If mixer performance tests have been made in accordance with Annex A1, the acceptable mixing time is permitted to be
reduced to the time equal to or greater than that used in the qualification testing. If the mixing time is so reduced the maximum
time of mixing shall not exceed this reduced time by more than 60 s for air-entrained concrete. Mixer performance tests shall be
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repeated whenever the appearance of the concrete or a comparison of coarse aggregate content of separate samples as described
in Annex A1 indicates that adequate mixing has not been accomplished.
12.4 Shrink-Mixed Concrete—Concrete that is first partially mixed in a stationary mixer, and then mixed completely in a truck
mixer, shall conform to the following: The time of partial mixing shall be the minimum time required to intermingle the
ingredients. After transfer to a truck mixer the amount of mixing at the designated mixing speed shall be that necessary to meet
the requirements for uniformity of concrete as indicated in Annex A1. Additional turning of the mixer, if any, shall be at a
designated agitating speed.
12.5 Truck-Mixed Concrete—Concrete that is completely mixed in a truck mixer for 70 to 100 revolutions at the mixing speed
designated by the truck mixer manufacturer shall produce uniformly mixed concrete as defined in Annex A1. The start of mixing
shall be when all the materials have been loaded in the mixer. If requirements for uniformity of concrete indicated in Annex A1
are not met with 100 revolutions of mixing that mixer shall not be used until the condition is corrected, except as provided in 11.5.
If satisfactory performance is found in one truck mixer, the performance of mixers of substantially the same design and condition
of blades are permitted to be regarded as satisfactory. Additional revolutions of the mixer beyond the number found to produce
the required uniformity of concrete shall be at a designated agitating speed.
NOTE 22—Truck mixers of similar design bearing a Performance Rating plate of the Truck Mixer Manufacturers Bureau have been tested for their ability
to produce uniformly mixed concrete in accordance with Annex A1.
12.6 When a truck mixer or truck agitator is used for transporting concrete that has been completely mixed in a stationary mixer,
any turning during transportation shall be at the speed designated by the manufacturer of the equipment as agitating speed.
12.7 For concrete delivered in truck mixers, no water from the truck water system or elsewhere shall be added after the initial
introduction of water during batching, except as permitted in 12.8, and if on arrival at the job site the slump or slump flow needs
to be increased to comply with the requirement stated in the purchase order. Unless otherwise stated, obtain the required slump
or slump flo
...