ASTM C359-21

Standard Test Method for Early Stiffening of Hydraulic-Cement (Mortar Method)

SIGNIFICANCE AND USE
5.1 The purpose of this test method is to determine the degree to which a cement mortar develops early stiffening. It is intended for use by those interested in methods for determining the potential early stiffening of hydraulic-cement.  
5.2 When used for estimating the relative tendency of a cement to manifest early stiffening, a judgment may be made by comparing the behavior in the penetration series (see 10.4.1 and 10.4.2) and the remix procedure (see 10.4.3) to differentiate a relatively less serious and less persistent tendency to early stiffening (false set) from one that is more persistent and, consequently, more serious (flash set).  
5.3 Severe false setting in a cement may cause difficulty from a placing and handling standpoint, but it is not likely to cause difficulties where concrete is mixed for a longer time than usual, as usually occurs in transit mixing, or where it is remixed prior to placing or transporting, in concrete pumping operations. It is most likely noticed where concrete is mixed for a short period of time in stationary mixers and transported to the forms in non-agitating equipment, as on some paving jobs, and when concrete is made in an on-site batch plant.  
5.4 Cements with severe false setting usually require slightly more mixing water to produce the same consistency, which may result in slightly lower strengths and increased drying shrinkage.  
5.5 Early stiffening resulting from false set is not likely to cause a cement to fail the applicable time of setting requirement.  
5.6 Early stiffening resulting from flash set, depending on severity, can cause a cement to fail the applicable time of setting requirement.
SCOPE
1.1 This test method covers the determination of early stiffening in hydraulic-cement mortar.  
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.  
1.3 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the standard.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. (Warning—Fresh hydraulic-cementitious mixtures are caustic and may cause chemical burns to skin and tissue upon prolonged exposure.2)  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 14-Dec-2021
• ICS: 91.100.10 - Cement. Gypsum. Lime. Mortar
• Technical Committee: C01 - Cement
• Drafting Committee: C01.30 - Time of Set

Relations

• Refers: ASTM C219-24 - Standard Terminology Relating to Hydraulic and Other Inorganic Cements
• Effective Date: 01-Apr-2024
• 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 C219-20a - Standard Terminology Relating to Hydraulic and Other Inorganic Cements
• Effective Date: 01-Aug-2020
• Refers: ASTM C305-20 - Standard Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency
• Effective Date: 15-Jul-2020
• Refers: ASTM C219-20 - Standard Terminology Relating to Hydraulic and Other Inorganic Cements
• Effective Date: 01-Apr-2020
• Refers: ASTM C185-20 - Standard Test Method for Air Content of Hydraulic Cement Mortar
• Effective Date: 01-Apr-2020
• Refers: ASTM C185-19 - Standard Test Method for Air Content of Hydraulic Cement Mortar
• Effective Date: 01-Dec-2019
• Refers: ASTM C219-19a - Standard Terminology Relating to Hydraulic and Other Inorganic Cements
• Effective Date: 15-Nov-2019
• Refers: ASTM C219-19 - Standard Terminology Relating to Hydraulic Cement
• Effective Date: 01-Jun-2019
• Refers: ASTM C1005-18 - Standard Specification for Reference Masses and Devices for Determining Mass and Volume for Use in the Physical Testing of Hydraulic Cements
• Effective Date: 01-May-2018
• Refers: ASTM C1005-17 - Standard Specification for Reference Masses and Devices for Determining Mass and Volume for Use in the Physical Testing of Hydraulic Cements
• Effective Date: 15-Mar-2017
• Refers: ASTM C185-15 - Standard Test Method for Air Content of Hydraulic Cement Mortar
• Effective Date: 01-Jul-2015
• Refers: ASTM C219-14 - Standard Terminology Relating to Hydraulic Cement
• Effective Date: 01-Jul-2014
• Refers: ASTM C511-13 - Standard Specification for Mixing Rooms, Moist Cabinets, Moist Rooms, and Water Storage Tanks Used in the Testing of Hydraulic Cements and Concretes
• Effective Date: 01-Dec-2013

Overview

ASTM C359-21 is the internationally recognized standard test method for evaluating early stiffening in hydraulic-cement mortar, commonly known as the "Mortar Method." Developed by ASTM International, this method is crucial for assessing the initial workability and placement characteristics of hydraulic-cement by measuring its early tendency to set, known as false set and flash set. Early stiffening can affect cement handling, mixing, and final performance, making this test valuable for producers, specifiers, and users of hydraulic cements in the construction sector.

Key Topics

• Early Stiffening: The standard identifies and distinguishes between two main types of early stiffening in hydraulic-cement:

  • False Set: Characterized by premature stiffening without significant heat evolution, which can be corrected by additional mixing without extra water.
  • Flash Set: Marked by rapid loss of plasticity, notable heat generation, and cannot be reversed by additional mixing alone.

• Test Method:

  • A standardized mortar is prepared with specified ratios of cement, standard sand, and water.
  • Penetration tests are performed at defined intervals using a modified Vicat apparatus to measure changes in workability.
  • After the initial tests, the mortar is remixed and tested to determine the extent of stiffening recovery.

• Reporting: The standard outlines requirements for reporting mixing water, penetration values at various intervals, early stiffening amount, average stiffening rate, and stiffening recovery.

• Precision and Consistency: Includes statistical criteria for intra- and inter-laboratory variability, ensuring reliable and repeatable results.

Applications

ASTM C359-21 is widely used in several critical aspects of the cement and concrete industry:

• Quality Control: Cement manufacturers and users rely on this standard to identify and manage cements susceptible to early stiffening, ensuring consistent product quality and batch performance.

• Troubleshooting: Contractors and quality assurance professionals employ the method to diagnose problems with mortar workability that may impact placement, compaction, or finishing, especially in high-speed or on-site batch mixing scenarios.

• Specification Compliance: The method helps verify cement compliance with performance specifications, particularly those related to setting time and workability requirements.

• Product Development: R&D and technical teams use these tests when formulating new hydraulic-cement blends, admixtures, or when sourcing alternative materials to ensure workability is within industry tolerances.

Related Standards

ASTM C359-21 makes reference to numerous complementary ASTM standards, which together form a comprehensive framework for cement and mortar testing:

• ASTM C183/C183M: Sampling and amount of testing of hydraulic cement.
• ASTM C185: Air content measurement in hydraulic cement mortar.
• ASTM C187: Determination of water requirement for cement consistency.
• ASTM C219: Terminology relating to hydraulic and other inorganic cements.
• ASTM C305: Mechanical mixing of hydraulic cement pastes and mortars.
• ASTM C511: Environmental conditions for cement and concrete testing.
• ASTM C670: Practices for preparing precision and bias statements.
• ASTM C778: Standard sand specification.
• ASTM C1005: Reference masses and volume devices.
• ASTM D1193: Specification for reagent water.
• ASTM E2251: Liquid-in-glass precision thermometers.

Practical Value

Employing ASTM C359-21 ensures early identification and management of cements prone to early stiffening, reducing the risk of placement issues, compromised strength, or increased drying shrinkage in concrete structures. Its adoption in quality control protocols helps minimize costly in-field problems and supports compliance with global construction standards. This method provides essential data for adjusting mixing processes and selecting compatible cementitious materials for varied construction applications.

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: C359 − 21
Standard Test Method for
Early Stiffening of Hydraulic-Cement (Mortar Method)
This standard is issued under the fixed designation C359; 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* mal Consistency of Hydraulic Cement Paste
C219 Terminology Relating to Hydraulic and Other Inor-
1.1 This test method covers the determination of early
ganic Cements
stiffening in hydraulic-cement mortar.
C305 Practice for Mechanical Mixing of Hydraulic Cement
1.2 The values stated in SI units are to be regarded as
Pastes and Mortars of Plastic Consistency
standard. The values given in parentheses after SI units are
C511 Specification for Mixing Rooms, Moist Cabinets,
provided for information only and are not considered standard.
Moist Rooms, and Water Storage Tanks Used in the
Testing of Hydraulic Cements and Concretes
1.3 The text of this standard references notes and footnotes
which provide explanatory material. These notes and footnotes C670 Practice for Preparing Precision and Bias Statements
for Test Methods for Construction Materials
(excluding those in tables and figures) shall not be considered
as requirements of the standard. C778 Specification for Standard Sand
C1005 Specification for Reference Masses and Devices for
1.4 This standard does not purport to address all of the
DeterminingMassandVolumeforUseinPhysicalTesting
safety concerns, if any, associated with its use. It is the
of Hydraulic Cements
responsibility of the user of this standard to establish appro-
E2251 Specification for Liquid-in-Glass ASTM Thermom-
priate safety, health, and environmental practices and deter-
eters with Low-Hazard Precision Liquids
mine the applicability of regulatory limitations prior to use.
(Warning—Fresh hydraulic-cementitious mixtures are caustic
3. Terminology
and may cause chemical burns to skin and tissue upon
3.1 For definitions of terms used in this test method, refer to
prolonged exposure. )
Terminology C219.
1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard-
4. Summary of Test Method
ization established in the Decision on Principles for the
4.1 Amortar is prepared with the cement to be tested, using
Development of International Standards, Guides and Recom-
specifiedquantitiesofcement,standardsand,andanamountof
mendations issued by the World Trade Organization Technical
water that will produce a mortar with an initial penetration of
Barriers to Trade (TBT) Committee.
46 63mm,usingthemodifiedVicatapparatus.Measurements
of penetration are made at stipulated intervals after the begin-
2. Referenced Documents
ning of the mixing procedure. Upon completion of the first
2.1 ASTM Standards:
series of penetration measurements, the mortar is returned to
C183/C183M Practice for Sampling and the Amount of
the mixer to be remixed. Following the remix procedure, an
Testing of Hydraulic Cement
additional penetration, termed the remix penetration, is deter-
C185 Test Method for Air Content of Hydraulic Cement
mined. The report is a tabulation of the penetration measure-
Mortar
ments and the amount of mixing water used.
C187 Test Method for Amount of Water Required for Nor-
5. Significance and Use
5.1 The purpose of this test method is to determine the
This test method is under the jurisdiction ofASTM Committee C01 on Cement
degree to which a cement mortar develops early stiffening. It is
and is the direct responsibility of Subcommittee C01.30 on Time of Set.
intendedforusebythoseinterestedinmethodsfordetermining
Current edition approved Dec. 15, 2021. Published December 2021. Originally
approved in 1955. Last previous edition approved in 2020 as C359 – 20. DOI:
the potential early stiffening of hydraulic-cement.
10.1520/C0359-21.
5.2 When used for estimating the relative tendency of a
Section on Safety, Manual of Cement Testing, Annual Book of ASTM
Standards, Vol 04.01.
cement to manifest early stiffening, a judgment may be made
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
by comparing the behavior in the penetration series (see 10.4.1
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
and 10.4.2) and the remix procedure (see 10.4.3) to differen-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. tiate a relatively less serious and less persistent tendency to
*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
C359 − 21
early stiffening (false set) from one that is more persistent and,
consequently, more serious (flash set).
5.3 Severe false setting in a cement may cause difficulty
from a placing and handling standpoint, but it is not likely to
cause difficulties where concrete is mixed for a longer time
than usual, as usually occurs in transit mixing, or where it is
remixed prior to placing or transporting, in concrete pumping
operations. It is most likely noticed where concrete is mixed
for a short period of time in stationary mixers and transported
to the forms in non-agitating equipment, as on some paving
jobs, and when concrete is made in an on-site batch plant.
FIG. 1 Container for Early Stiffening Tests
5.4 Cements with severe false setting usually require
slightly more mixing water to produce the same consistency,
which may result in slightly lower strengths and increased
drying shrinkage.
7. Reagents and Materials
5.5 Early stiffening resulting from false set is not likely to
7.1 Standard Sand, 20-30 and Graded, conforming to the
cause a cement to fail the applicable time of setting require-
requirements of Specification C778.
ment.
7.2 Mixing Water—Potable water is satisfactory for routine
5.6 Early stiffening resulting from flash set, depending on
tests. Use reagent water for all referee and cooperative tests.
severity, can cause a cement to fail the applicable time of
setting requirement.
8. Sampling
8.1 When the test is part of acceptance testing, sample the
6. Apparatus
cement in accordance with Practice C183/C183M.
6.1 Vicat Apparatus, conforming to the requirements of
Fig. 1 in Test Method C187, with the following modifications:
9. Conditioning
6.1.1 The 1 mm needle shall be replaced by a mass, such
9.1 Maintain the temperature and humidity of the mixing
that the total mass of the 10 mm plunger, indicator, and added
room in accordance with Specification C511.
mass shall be 400 6 0.5 g.
9.2 The mixing apparatus shall be within the temperature
6.2 Spoon, conforming to the requirements of Test Method
range of the mixing room prior to testing.
C185.
NOTE 1—This test method may adjust the temperature of either the mix
water, cement, sand or a combination in order to obtain a specified mortar
6.3 Mixer, Bowl, Paddle, and Scraper, conforming to the
temperature range. Starting the test with the initial dry material and water
requirements of Practice C305.
temperatures within the mixing room temperature range is recommended.
6.4 Glass Graduates, 200 or 250 mL capacity, conforming
10. Procedure
to the requirements of Specification C1005.
10.1 Batch—Mix at one time 600 g of cement, 300 g of
6.5 Masses and Mass Determining Devices, conforming to
graded standard sand, 300 g of 20-30 standard sand, and an
the requirements of Specification C1005. The devices for
amount of water that produces a mortar with an initial
determining mass shall be evaluated for continuing precise
penetration of 46 6 3 mm.
performance utilizing the procedure in Specification C1005,
Appendix X1, using a verification check mass of approxi-
10.2 Mixing of Mortar—Mix in the mechanical mixer as
mately 1000 g. follows:
10.2.1 Place the sand and cement in the dry bowl, and mix
6.6 Thermometer, ASTM No. S12C or S12F, conforming to
the dry materials for a few seconds with the spoon.
the requirements of Specification E2251.
10.2.2 Place the bowl in the mixer, set the paddle in place,
6.7 Flat Trowel, having a sharpened straight-edged steel and mix the dry materials for 10 s at a slow speed (140 6
blade 100 to 150 mm in length. The edges when placed on a 5 r⁄min).
plane surface shall not depart from straightness by more than 10.2.3 With the mixer operating at a slow speed (140 6
1 mm.
5 r⁄min), add the entire quantity of mixing water within 5 s.
Stop the mixer, quickly change to a medium speed (285 6
6.8 Clock Timer, having a readability to the nearest second.
10 r/min), and continue the mixing for 1 min, timing from the
6.9 Containers, approximately 50 by 50 by 150 mm (2 by 2 first addition of water.
by 6 in.) inside dimensions (Fig. 1). These containers, which 10.2.4 Stop the mixer, scrape the sides of the mixing bowl
may be made of any
...

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: C359 − 20 C359 − 21
Standard Test Method for
Early Stiffening of Hydraulic-Cement (Mortar Method)
This standard is issued under the fixed designation C359; 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 covers the determination of early stiffening in hydraulic-cement mortar.
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for
information only and are not considered standard.
1.3 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes
(excluding those in tables and figures) shall not be considered as requirements of the standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use. (Warning—Fresh hydraulic-cementitious mixtures are caustic and may cause chemical burns
to skin and tissue upon prolonged exposure. )
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:
C183/C183M Practice for Sampling and the Amount of Testing of Hydraulic Cement
C185 Test Method for Air Content of Hydraulic Cement Mortar
C187 Test Method for Amount of Water Required for Normal Consistency of Hydraulic Cement Paste
C219 Terminology Relating to Hydraulic and Other Inorganic Cements
C305 Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency
C511 Specification for Mixing Rooms, Moist Cabinets, Moist Rooms, and Water Storage Tanks Used in the Testing of Hydraulic
Cements and Concretes
C670 Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials
C778 Specification for Standard Sand
C1005 Specification for Reference Masses and Devices for Determining Mass and Volume for Use in Physical Testing of
Hydraulic Cements
D1193 Specification for Reagent Water
E2251 Specification for Liquid-in-Glass ASTM Thermometers with Low-Hazard Precision Liquids
This test method is under the jurisdiction of ASTM Committee C01 on Cement and is the direct responsibility of Subcommittee C01.30 on Time of Set.
Current edition approved Oct. 1, 2020Dec. 15, 2021. Published November 2020December 2021. Originally approved in 1955. Last previous edition approved in 20182020
as C359 – 18.C359 – 20. DOI: 10.1520/C0359-2010.1520/C0359-21.
Section on Safety, Manual of Cement Testing, Annual Book of ASTM Standards, Vol 04.01.
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
C359 − 21
3. Terminology
3.1 Definitions:
3.1.1 early stiffening, n—the early development of stiffness in the working characteristics of a hydraulic-cement paste, mortar, or
concrete; varieties include false set and flash set.
3.1.2 false set, n—the early development of stiffness in the working characteristics of a hydraulic-cement paste, mortar, or concrete
without the evolution of much heat, which stiffness can be dispelled and plasticity regained by further mixing without addition of
water; also known as “grab set,” “premature stiffening,” “hesitation set,” and “rubber set.”
3.1.3 flash set, n—the early development of stiffness in the working characteristics of a hydraulic-cement paste, mortar, or
concrete, usually with the evolution of considerable heat, which stiffness cannot be dispelled nor can the plasticity be regained by
further mixing without addition of water; also known as “quick set.”
3.1 For definitions of terms used in this test method, refer to Terminology C219.
4. Summary of Test Method
4.1 A mortar is prepared with the cement to be tested, using specified quantities of cement, standard sand, and an amount of water
that will produce a mortar with an initial penetration of 46 6 3 mm, using the modified Vicat apparatus. Measurements of
penetration are made at stipulated intervals after the beginning of the mixing procedure. Upon completion of the first series of
penetration measurements, the mortar is returned to the mixer to be remixed. Following the remix procedure, an additional
penetration, termed the remix penetration, is determined. The report is a tabulation of the penetration measurements and the amount
of mixing water used.
5. Significance and Use
5.1 The purpose of this test method is to determine the degree to which a cement mortar develops early stiffening. It is intended
for use by those interested in methods for determining the potential early stiffening of hydraulic-cement.
5.2 When used for estimating the relative tendency of a cement to manifest early stiffening, a judgment may be made by
comparing the behavior in the penetration series (see 10.4.1 and 10.4.2) and the remix procedure (see 10.4.3) to differentiate a
relatively less serious and less persistent tendency to early stiffening (false set) from one that is more persistent and, consequently,
more serious (flash set).
5.3 Severe false setting in a cement may cause difficulty from a placing and handling standpoint, but it is not likely to cause
difficulties where concrete is mixed for a longer time than usual, as usually occurs in transit mixing, or where it is remixed prior
to placing or transporting, in concrete pumping operations. It is most likely noticed where concrete is mixed for a short period of
time in stationary mixers and transported to the forms in non-agitating equipment, as on some paving jobs, and when concrete is
made in an on-site batch plant.
5.4 Cements with severe false setting usually require slightly more mixing water to produce the same consistency, which may
result in slightly lower strengths and increased drying shrinkage.
5.5 Early stiffening resulting from false set is not likely to cause a cement to fail the applicable time of setting requirement.
5.6 Early stiffening resulting from flash set, depending on severity, can cause a cement to fail the applicable time of setting
requirement.
6. Apparatus
6.1 Vicat Apparatus, conforming to the requirements of Fig. 1 in Test Method C187, with the following modifications:
6.1.1 The 1 mm needle shall be replaced by a mass, such that the total mass of the 10 mm plunger, indicator, and added mass shall
be 400 6 0.5 g.
C359 − 21
6.2 Spoon, conforming to the requirements of Test Method C185.
6.3 Mixer, Bowl, Paddle, and Scraper, conforming to the requirements of Practice C305.
6.4 Glass Graduates, 200 or 250 mL capacity, conforming to the requirements of Specification C1005.
6.5 Masses and Mass Determining Devices, conforming to the requirements of Specification C1005. The devices for determining
mass shall be evaluated for continuing precise performance utilizing the procedure in Specification C1005, Appendix X1, using
a verification check mass of approximately 1000 g.
6.6 Thermometer, ASTM No. S12C or S12F, conforming to the requirements of Specification E2251.
6.7 Flat Trowel, having a sharpened straight-edged steel blade 100 to 150 mm in length. The edges when placed on a plane surface
shall not depart from straightness by more than 1 mm.
6.8 Clock Timer, having a readability to the nearest second.
6.9 Containers, approximately 50 by 50 by 150 mm (2 by 2 by 6 in.) inside dimensions (Fig. 1). These containers, which may
be made of any suitable materials such as sheet metal or plastic, shall be rigid, watertight, and at least 50 mm (2 in.) deep.
7. Reagents and Materials
7.1 Standard Sand, 20-30 and Graded, conforming to the requirements of Specification C778.
7.2 Mixing Water—Potable water is satisfactory for routine tests. For Use reagent water for all referee and cooperative tests,
reagent water conforming to the requirements of Specification tests.D1193 for Type III or Type IV grades of reagent water shall
be used.
8. Sampling
8.1 When the test is part of acceptance testing, sample the cement in accordance with Practice C183/C183M.
9. Conditioning
9.1 Maintain the temperature and humidity of the mixing room in accordance with Specification C511.
9.2 The mixing apparatus shall be within the temperature range of the mixing room prior to testing.
NOTE 1—This test method may adjust the temperature of either the mix water, cement, sand or a combination in order to obtain a specified mortar
temperature range. Starting the test with the initial dry material and water temperatures within the mixing room temperature range is recommended.
FIG. 1 Container for Early Stiffening Tests
C359 − 21
10. Procedure
10.1 Batch—Mix at one time 600 g of cement, 300 g of graded standard sand, 300 g of 20-30
...