ASTM C1260-23

Standard Test Method for Potential Alkali Reactivity of Aggregates (Mortar-Bar Method)

SIGNIFICANCE AND USE
4.1 This test method provides a means of detecting the potential of an aggregate intended for use in concrete for undergoing alkali-silica reaction resulting in potentially deleterious internal expansion. It is based on the NBRI Accelerated Test Method (1-4).3 It is especially useful for aggregates that react slowly or produce expansion late in the reaction. However, it does not evaluate combinations of aggregates with cementitious materials nor are the test conditions representative of those encountered by concrete in service.  
4.2 Because the specimens are exposed to a NaOH solution, the alkali content of the cement is not a significant factor in affecting expansions.  
4.3 Results of tests conducted on an aggregate as described herein should form a part of the basis for a decision as to whether precautions should be taken against excessive expansion due to alkali-silica reaction. Refer to Guide C1778 for the interpretation of the test results from Test Method C1260.
SCOPE
1.1 This test method permits detection, within 16 days, of the potential for deleterious alkali-silica reaction of aggregate in mortar bars.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. When this test method refers to combined-unit standards, the selection of the measurement systems is at the user’s discretion.  
1.3 The text of this test method refers to notes and footnotes that provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of this test method.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. A specific precautionary statement is given in the section on Reagents.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 14-Nov-2023
• ICS: 91.100.10 - Cement. Gypsum. Lime. Mortar
• Technical Committee: C09 - Concrete and Concrete Aggregates
• Drafting Committee: C09.50 - Aggregate Reactions in Concrete

Relations

• Replaces: ASTM C1260-22 - Standard Test Method for Potential Alkali Reactivity of Aggregates (Mortar-Bar Method)
• Effective Date: 15-Nov-2023
• Refers: ASTM C670-24a - Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials
• Effective Date: 01-Feb-2024
• Refers: ASTM C670-24 - Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials
• Effective Date: 01-Jan-2024
• Refers: ASTM C109/C109M-23 - Standard Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 50 mm [2 in.] Cube Specimens)
• Effective Date: 15-Dec-2023
• Refers: ASTM C1778-23 - Standard Guide for Reducing the Risk of Deleterious Alkali-Aggregate Reaction in Concrete
• Effective Date: 01-Dec-2023
• Refers: ASTM C1260-23 - Standard Test Method for Potential Alkali Reactivity of Aggregates (Mortar-Bar Method)
• Effective Date: 15-Nov-2023
• Refers: ASTM C109/C109M-21 - Standard Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in. or [50 mm] Cube Specimens)
• Effective Date: 15-Jul-2021
• Refers: ASTM C670-15 - Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials
• Effective Date: 15-Jun-2015
• Refers: ASTM C127-15 - Standard Test Method for Relative Density (Specific Gravity) and Absorption of Coarse Aggregate (Withdrawn 2024)
• Effective Date: 01-Jan-2015
• Referred By: ASTM D7705/D7705M-12(2019) - Standard Test Method for Alkali Resistance of Fiber Reinforced Polymer (FRP) Matrix Composite Bars used in Concrete Construction
• Effective Date: 15-Nov-2023
• Referred By: ASTM C1260-23 - Standard Test Method for Potential Alkali Reactivity of Aggregates (Mortar-Bar Method)
• Effective Date: 15-Nov-2023
• Referred By: ASTM C1567-23 - Standard Test Method for Determining the Potential Alkali-Silica Reactivity of Combinations of Cementitious Materials and Aggregate (Accelerated Mortar-Bar Method)
• Effective Date: 15-Nov-2023
• Referred By: ASTM C1293/C1293M-23 - Standard Test Method for Determination of Length Change of Concrete Due to Alkali-Silica Reaction
• Effective Date: 15-Nov-2023
• Referred By: ASTM C1778-22 - Standard Guide for Reducing the Risk of Deleterious Alkali-Aggregate Reaction in Concrete
• Effective Date: 15-Nov-2023

Overview

ASTM C1260-23: Standard Test Method for Potential Alkali Reactivity of Aggregates (Mortar-Bar Method) provides a reliable and accelerated laboratory procedure to identify aggregates that may potentially cause alkali-silica reaction (ASR) when used in concrete. Developed by ASTM International, this standard helps in detecting deleterious internal expansion in aggregates due to alkali-silica reactivity within a 16-day period. The methodology is based on the NBRI Accelerated Test Method and is especially valuable for assessing aggregates that react slowly or show late-stage expansion.

The ASTM C1260-23 test does not evaluate specific aggregate-cement combinations nor does it replicate exact field service conditions of concrete. However, it serves as a critical screening tool to determine if further precautions are required before aggregates are approved for use in concrete structures.

Key Topics

• Purpose of the Test Method: Detects aggregates susceptible to alkali-silica reactivity, which can lead to internal expansion, cracking, and deterioration in concrete.
• Test Procedure: Involves immersing mortar bars made with the test aggregate in a sodium hydroxide (NaOH) solution at an elevated temperature, then measuring length changes to indicate expansion.
• Accelerated Results: The method allows for the identification of potential ASR problems in just 16 days.
• Result Interpretation: Test results form an important part of the decision-making process for aggregate qualification. For guidance on interpreting results, users are referred to ASTM C1778.
• Limitation: The test is most effective for the aggregate being tested alone and does not simulate all real-world concrete environments or cementitious materials combinations.
• Safety Considerations: Specific safety precautions are included for handling chemicals, especially NaOH, as well as ensuring laboratory best practices.

Applications

The ASTM C1260-23 standard is widely adopted in the construction and materials testing industries for:

• Aggregate Screening: Before approving aggregate sources for use in structural concrete projects, material suppliers and quality assurance laboratories employ this standard to identify potentially deleterious materials.
• Risk Management: Results guide the need for further testing or mitigation measures, such as using supplementary cementitious materials or altering mix designs to reduce ASR risk.
• Specification Compliance: Owners, engineers, and contractors reference this standard in construction specifications to ensure only ASR-resistant aggregates are used, thereby enhancing the long-term durability of concrete structures.
• Product Development: Cement and aggregate producers use test outcomes to refine products and meet marketplace demands for ASR resistance.
• Research and Quality Control: Academic and research institutions employ the method for scientific studies focused on aggregate reactivity and concrete durability.

Related Standards

ASTM C1260-23 is closely associated with several other key ASTM standards in the field of concrete and aggregate testing, including:

• ASTM C125: Terminology Relating to Concrete and Concrete Aggregates
• ASTM C127 & C128: Test Methods for Determining Relative Density and Absorption of Coarse and Fine Aggregates
• ASTM C109/C109M: Test Method for Compressive Strength of Hydraulic Cement Mortars
• ASTM C305: Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars
• ASTM C490/C490M: Practice for Use of Apparatus for Determining Length Change
• ASTM C511: Specification for Moist Rooms and Water Storage for Cement and Concrete Testing
• ASTM C595/C595M: Specification for Blended Hydraulic Cements
• ASTM D1193: Specification for Reagent Water
• ASTM C1778: Guide for Reducing the Risk of Deleterious Alkali-Aggregate Reaction in Concrete

Keywords: ASTM C1260, potential alkali reactivity, aggregates, mortar-bar method, alkali-silica reaction, ASR, concrete durability, aggregate testing, sodium hydroxide, accelerated mortar bar test

This concise overview of ASTM C1260-23 highlights its essential role in assessing aggregate reactivity and supporting durable concrete construction through industry-standard methods.

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: C1260 − 23
Standard Test Method for
Potential Alkali Reactivity of Aggregates (Mortar-Bar
Method)
This standard is issued under the fixed designation C1260; 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.
1. Scope* C125 Terminology Relating to Concrete and Concrete Ag-
gregates
1.1 This test method permits detection, within 16 days, of
C127 Test Method for Relative Density (Specific Gravity)
the potential for deleterious alkali-silica reaction of aggregate
and Absorption of Coarse Aggregate
in mortar bars.
C128 Test Method for Relative Density (Specific Gravity)
1.2 The values stated in SI units are to be regarded as
and Absorption of Fine Aggregate
standard. No other units of measurement are included in this
C150/C150M Specification for Portland Cement
standard. When this test method refers to combined-unit
C305 Practice for Mechanical Mixing of Hydraulic Cement
standards, the selection of the measurement systems is at the
Pastes and Mortars of Plastic Consistency
user’s discretion.
C490/C490M Practice for Use of Apparatus for the Deter-
1.3 The text of this test method refers to notes and footnotes mination of Length Change of Hardened Cement Paste,
Mortar, and Concrete
that provide explanatory material. These notes and footnotes
(excluding those in tables and figures) shall not be considered C511 Specification for Mixing Rooms, Moist Cabinets,
Moist Rooms, and Water Storage Tanks Used in the
as requirements of this test method.
Testing of Hydraulic Cements and Concretes
1.4 This standard does not purport to address all of the
C595/C595M Specification for Blended Hydraulic Cements
safety concerns, if any, associated with its use. It is the
C670 Practice for Preparing Precision and Bias Statements
responsibility of the user of this standard to establish appro-
for Test Methods for Construction Materials
priate safety, health, and environmental practices and deter-
C1260 Test Method for Potential Alkali Reactivity of Ag-
mine the applicability of regulatory limitations prior to use. A
gregates (Mortar-Bar Method)
specific precautionary statement is given in the section on
C1778 Guide for Reducing the Risk of Deleterious Alkali-
Reagents.
Aggregate Reaction in Concrete
1.5 This international standard was developed in accor-
D1193 Specification for Reagent Water
dance with internationally recognized principles on standard-
E11 Specification for Woven Wire Test Sieve Cloth and Test
ization established in the Decision on Principles for the
Sieves
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
3. Terminology
Barriers to Trade (TBT) Committee.
3.1 Definitions—For definitions of other terms relating to
2. Referenced Documents
concrete or aggregates, see Terminology C125.
3.1.1 relative density (OD), n—as defined in Test Methods
2.1 ASTM Standards:
C127 or C128, for coarse and fine aggregates, respectively.
C109/C109M Test Method for Compressive Strength of
Hydraulic Cement Mortars (Using 2-in. or [50 mm] Cube
4. Significance and Use
Specimens)
4.1 This test method provides a means of detecting the
potential of an aggregate intended for use in concrete for
This test method is under the jurisdiction of ASTM Committee C09 on
undergoing alkali-silica reaction resulting in potentially delete-
Concrete and Concrete Aggregates and is the direct responsibility of Subcommittee
rious internal expansion. It is based on the NBRI Accelerated
C09.50 on Aggregate Reactions in Concrete.
Current edition approved Nov. 15, 2023. Published November 2023. Originally
Test Method (1-4). It is especially useful for aggregates that
approved in 1989. Last previous edition approved in 2022 as C1260 – 22. DOI:
react slowly or produce expansion late in the reaction.
10.1520/C1260-23.
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 boldface numbers in parentheses refer to a list of references at the end of
the ASTM website. the text.
*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
C1260 − 23
However, it does not evaluate combinations of aggregates with volume of a mortar bar may be taken as 184 mL. Include
cementitious materials nor are the test conditions representa- sufficient test solution to ensure complete immersion of the
tive of those encountered by concrete in service. mortar bars.
6.3.1 Warning—Before using NaOH, review: (1) the safety
4.2 Because the specimens are exposed to a NaOH solution,
precautions for using NaOH; (2) first aid for burns; and (3) the
the alkali content of the cement is not a significant factor in
emergency response to spills, as described in the manufactur-
affecting expansions.
er’s Material Safety Data Sheet or other reliable safety litera-
4.3 Results of tests conducted on an aggregate as described
ture. NaOH can cause very severe burns and injury to unpro-
herein should form a part of the basis for a decision as to
tected skin and eyes. Suitable personal protective equipment
whether precautions should be taken against excessive expan-
should always be used. These should include full-face shields,
sion due to alkali-silica reaction. Refer to Guide C1778 for the
rubber aprons, and gloves impervious to NaOH. Gloves should
interpretation of the test results from Test Method C1260.
be checked periodically for pin holes.
5. Apparatus
7. Conditioning
5.1 The apparatus shall conform to Specification C490/
7.1 Maintain the temperature of the molding room and dry
C490M, except as follows:
materials at not less than 20 °C and not more than 27.5 °C. The
5.2 Sieves—Square hole, woven-wire cloth sieves, shall
temperature of the mixing water, and of the moist closet or
conform to Specification E11.
moist room, shall not vary from 23 °C by more than 2.0 °C.
5.3 Mixer, Paddle, and Mixing Bowl—Mixer, paddle, and
7.2 Maintain the relative humidity of the molding room at
mixing bowl shall conform to the requirements of Practice
not less than 50 %. The moist closet or room shall conform to
C305, except that the clearance between the lower end of the
Specification C511.
paddle and the bottom of the bowl shall be 5.1 mm 6 0.3 mm.
7.3 Maintain the storage oven or water bath in which the
5.4 Tamper and Trowel—The tamper and trowel shall con-
specimens are stored in the containers at a temperature of
form to Test Method C109/C109M.
80.0 °C 6 2.0 °C.
5.5 Containers—The containers shall be of such a nature
8. Sampling and Preparation of Test Specimens
that the bars can be totally immersed in either the water or 1N
8.1 Selection of Aggregate—Process materials proposed for
NaOH solution. The containers shall be made of material that
use as fine aggregate in concrete as described in the section on
can withstand prolonged exposure to 80 °C and must be
Preparation of Aggregate with a minimum of crushing. Process
resistant to a 1N NaOH solution (see Note 1). The containers
materials proposed for use as coarse aggregate in concrete by
must be so constructed that when used for storing specimens,
the loss or gain of moisture is prevented by tight-fitting covers, crushing to produce as nearly as practical a graded product
from which a sample can be obtained. Grade the sample as
by sealing, or both (see Note 2). The bars in the solution must
be placed and supported so that the solution has access to the prescribed in Table 1. The sample shall represent the compo-
sition of the coarse aggregate as proposed for use.
entire surface of the bar; therefore, it should be ensured that the
specimens do not touch the sides of the container or each other. 8.1.1 When a given quarried material is proposed for use
both as coarse and as fine aggregate, test it only by selection of
The specimens, if stood upright in the solution, shall not be
supported by the metal gauge stud. an appropriate sample crushed to the fine aggregates sizes,
unless there is reason to expect that the coarser size fractions
NOTE 1—The NaOH solution will corrode glass or metal containers.
have a different composition that the finer sizes and that these
NOTE 2—Some microwave-proof food storage containers made of
differences might significantly affect expansion due to reaction
polypropylene or high-density polyethylene have been found to be
acceptable. with the alkalies in cement or from the environment of service.
In this case test the coarser size fractions in a manner similar
5.6 Oven, or Water Bath—A convection oven or water bath
to that employed in testing the fine aggregate sizes.
with temperature control maintaining 80.0 °C 6 2.0 °C.
8.2 Preparation of Aggregate—Grade all aggregates to
6. Reagents
which this test method is applied in accordance with the
6.1 Sodium Hydroxide (NaOH)—USP or technical grade
requirements given in Table 1. Crush aggregates in which
+ −
may be used, provided the Na and OH concentrations are
sufficient quantities of the sizes specified in Table 1 do not exist
shown by chemical analysis to lie between 0.99N and 1.01N.
until the required material has been produced. In the case of
6.2 Purity of Water—Unless otherwise indicated, references
to water shall be understood to mean reagent water conforming
TABLE 1 Grading Requirements
to Type IV of Specification D1193.
Sieve Size
Mass, %
6.3 Sodium Hydroxide Solution—Each litre of solution shall
Passing Retained on
contain 40.0 g of NaOH dissolved in 900 mL of water, and
4.75 mm (No. 4) 2.36 mm (No. 8) 10
shall be diluted with additional distilled or deionized water to 2.36 mm (No. 8) 1.18 mm (No. 16) 25
1.18 mm (No. 16) 600 μm (No. 30) 25
obtain 1.0 L of solution. The volume proportion of sodium
600 μm (No. 30) 300 μm (No. 50) 25
hydroxide solution to mortar bars in a storage container shall
300 μm (No. 50) 150 μm (No. 100) 15
be 4 6 0.5 volumes of solution to 1 volume of mortar bars. The
C1260 − 23
aggregates containing insufficient amounts of one or more of mass shall be made up by recombining the portions retained on
the larger sizes listed in Table 1, and if no larger material is the various sieves in the grading prescribed in Table 1 (8.2).
available for crushing, the first size in which sufficient material Use a water-cement ratio equal to 0.47 by mass (see Note 5).
is available shall contain the cumulative percentage of material
NOTE 5—Ruggedness tests indicated that mortar bar expansions were
down to that size as determined from the grading specified in
less variable at a fixed water to cement ratio than when gaged to a constant
Table 1. When such procedures are required, make a special
flow (3).
note thereof in the test report. After the aggregate has been
8.4.4 Mixing of Mortar—Mix the mortar in accordance with
separated into the various sieve sizes, wash each size with a
the requirements of Practice C305.
water spray over the sieve to remove adhering dust and fine
8.4.5 Molding of Test Specimen
...

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: C1260 − 22 C1260 − 23
Standard Test Method for
Potential Alkali Reactivity of Aggregates (Mortar-Bar
Method)
This standard is issued under the fixed designation C1260; 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.
1. Scope*
1.1 This test method permits detection, within 16 days, of the potential for deleterious alkali-silica reaction of aggregate in mortar
bars.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. When
this test method refers to combined-unit standards, the selection of the measurement systems is at the user’s discretion.
1.3 The text of this test method refers to notes and footnotes that provide explanatory material. These notes and footnotes
(excluding those in tables and figures) shall not be considered as requirements of this test method.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use. A specific precautionary statement is given in the section on Reagents.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
C109/C109M Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in. or [50 mm] Cube Specimens)
C125 Terminology Relating to Concrete and Concrete Aggregates
C127 Test Method for Relative Density (Specific Gravity) and Absorption of Coarse Aggregate
C128 Test Method for Relative Density (Specific Gravity) and Absorption of Fine Aggregate
C150/C150M Specification for Portland Cement
C305 Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency
C490/C490M Practice for Use of Apparatus for the Determination of Length Change of Hardened Cement Paste, Mortar, and
Concrete
C511 Specification for Mixing Rooms, Moist Cabinets, Moist Rooms, and Water Storage Tanks Used in the Testing of Hydraulic
Cements and Concretes
C595/C595M Specification for Blended Hydraulic Cements
This test method is under the jurisdiction of ASTM Committee C09 on Concrete and Concrete Aggregates and is the direct responsibility of Subcommittee C09.50 on
Aggregate Reactions in Concrete.
Current edition approved Nov. 1, 2022Nov. 15, 2023. Published December 2022November 2023. Originally approved in 1989. Last previous edition approved in 20212022
as C1260 – 21.C1260 – 22. DOI: 10.1520/C1260-22.10.1520/C1260-23.
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
C1260 − 23
C670 Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials
C1260 Test Method for Potential Alkali Reactivity of Aggregates (Mortar-Bar Method)
C1778 Guide for Reducing the Risk of Deleterious Alkali-Aggregate Reaction in Concrete
D1193 Specification for Reagent Water
E11 Specification for Woven Wire Test Sieve Cloth and Test Sieves
3. Terminology
3.1 Definitions—For definitions of other terms relating to concrete or aggregates, see Terminology C125.
3.1.1 relative density (OD), n—as defined in Test Methods C127 or C128, for coarse and fine aggregates, respectively.
4. Significance and Use
4.1 This test method provides a means of detecting the potential of an aggregate intended for use in concrete for undergoing
alkali-silica reaction resulting in potentially deleterious internal expansion. It is based on the NBRI Accelerated Test Method (1-4).
It is especially useful for aggregates that react slowly or produce expansion late in the reaction. However, it does not evaluate
combinations of aggregates with cementitious materials nor are the test conditions representative of those encountered by concrete
in service.
4.2 Because the specimens are exposed to a NaOH solution, the alkali content of the cement is not a significant factor in affecting
expansions.
4.3 Results of tests conducted on an aggregate as described herein should form a part of the basis for a decision as to whether
precautions should be taken against excessive expansion due to alkali-silica reaction. Refer to Guide C1778 for the interpretation
of the test results from Test Method C1260.
5. Apparatus
5.1 The apparatus shall conform to Specification C490/C490M, except as follows:
5.2 Sieves—Square hole, woven-wire cloth sieves, shall conform to Specification E11.
5.3 Mixer, Paddle, and Mixing Bowl—Mixer, paddle, and mixing bowl shall conform to the requirements of Practice C305, except
that the clearance between the lower end of the paddle and the bottom of the bowl shall be 5.1 mm 6 0.3 mm.
5.4 Tamper and Trowel—The tamper and trowel shall conform to Test Method C109/C109M.
5.5 Containers—The containers shall be of such a nature that the bars can be totally immersed in either the water or 1N NaOH
solution. The containers shall be made of material that can withstand prolonged exposure to 80 °C and must be resistant to a 1N
NaOH solution (see Note 1). The containers must be so constructed that when used for storing specimens, the loss or gain of
moisture is prevented by tight-fitting covers, by sealing, or both (see Note 2). The bars in the solution must be placed and supported
so that the solution has access to the entire surface of the bar; therefore, it should be ensured that the specimens do not touch the
sides of the container or each other. The specimens, if stood upright in the solution, shall not be supported by the metal gauge stud.
NOTE 1—The NaOH solution will corrode glass or metal containers.
NOTE 2—Some microwave-proof food storage containers made of polypropylene or high-density polyethylene have been found to be acceptable.
5.6 Oven, or Water Bath—A convection oven or water bath with temperature control maintaining 80.0 °C 6 2.0 °C.
6. Reagents
+ −
6.1 Sodium Hydroxide (NaOH)—USP or technical grade may be used, provided the Na and OH concentrations are shown by
chemical analysis to lie between 0.99N and 1.01N.
The boldface numbers in parentheses refer to a list of references at the end of the text.
C1260 − 23
6.2 Purity of Water—Unless otherwise indicated, references to water shall be understood to mean reagent water conforming to
Type IV of Specification D1193.
6.3 Sodium Hydroxide Solution—Each litre of solution shall contain 40.0 g of NaOH dissolved in 900 mL of water, and shall be
diluted with additional distilled or deionized water to obtain 1.0 L of solution. The volume proportion of sodium hydroxide solution
to mortar bars in a storage container shall be 4 6 0.5 volumes of solution to 1 volume of mortar bars. The volume of a mortar
bar may be taken as 184 mL. Include sufficient test solution to ensure complete immersion of the mortar bars.
6.3.1 Warning—Before using NaOH, review: (1) the safety precautions for using NaOH; (2) first aid for burns; and (3) the
emergency response to spills, as described in the manufacturer’s Material Safety Data Sheet or other reliable safety literature.
NaOH can cause very severe burns and injury to unprotected skin and eyes. Suitable personal protective equipment should always
be used. These should include full-face shields, rubber aprons, and gloves impervious to NaOH. Gloves should be checked
periodically for pin holes.
7. Conditioning
7.1 Maintain the temperature of the molding room and dry materials at not less than 20 °C and not more than 27.5 °C. The
temperature of the mixing water, and of the moist closet or moist room, shall not vary from 23 °C by more than 2.0 °C.
7.2 Maintain the relative humidity of the molding room at not less than 50 %. The moist closet or room shall conform to
Specification C511.
7.3 Maintain the storage oven or water bath in which the specimens are stored in the containers at a temperature of 80.0 °C 6
2.0 °C.
8. Sampling and Preparation of Test Specimens
8.1 Selection of Aggregate—Process materials proposed for use as fine aggregate in concrete as described in the section on
Preparation of Aggregate with a minimum of crushing. Process materials proposed for use as coarse aggregate in concrete by
crushing to produce as nearly as practical a graded product from which a sample can be obtained. Grade the sample as prescribed
in Table 1. The sample shall represent the composition of the coarse aggregate as proposed for use.
8.1.1 When a given quarried material is proposed for use both as coarse and as fine aggregate, test it only by selection of an
appropriate sample crushed to the fine aggregates sizes, unless there is reason to expect that the coarser size fractions have a
different composition that the finer sizes and that these differences might significantly affect expansion due to reaction with the
alkalies in cement or from the environment of service. In this case test the coarser size fractions in a manner similar to that
employed in testing the fine aggregate sizes.
8.2 Preparation of Aggregate—Grade all aggregates to which this test method is applied in accordance with the requirements
given in Table 1. Crush aggregates in which sufficient quantities of the sizes specified in Table 1 do not exist until the required
material has been produced. In the case of aggregates containing insufficient amounts of one or more of the larger sizes listed in
Table 1, and if no larger material is available for crushing, the first size in which sufficient material is available shall contain the
cumulative percentage of material down to that size as determined from the grading specified in Table 1. When such procedures
are required, make a special note thereof in the test report. After the aggregate has been separated into the various sieve sizes, wash
each size with a water spray over the sieve to remove adhering dust and fine particles from the aggregate. Dry the portions retained
on the various sieves and, unless used immediately, store each such portion individually in a clean container provided with a
tight-fitting cover.
TABLE 1 Grading Requirements
Sieve Size
Mass, %
Passing Retained on
4.75 mm (No. 4) 2.36 mm (No. 8) 10
2.36 mm (No. 8) 1.18 mm (No. 16) 25
1.18 mm (No. 16) 600 μm (No. 30) 25
600 μm (No. 30) 300 μm (No. 50) 25
300 μm (No. 50) 150 μm (No. 100) 15
C1260 − 23
8.3 Selection and Preparation of Cement:
8.3.1 Reference Cement—Use a portland cement meeting the requirements of Specification C150/C150M or Specification
C595/C595M Type IL Cement (Note 3).
NOTE 3—The alkali content of the cement has been found to have negligible (3) or minor (5) effects on expansion in this test.
8.3.2 Preparation of Cement—Pass cement for use in this test through an 850-μm (No. 20) sieve to remove lumps before use.
8.4 Preparation of Test Specimens:
8.4.1 Number
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