ASTM C451-19

Standard Test Method for Early Stiffening of Hydraulic Cement (Paste Method)

SIGNIFICANCE AND USE
5.1 The purpose of this test method is to determine the degree to which a cement paste develops early stiffening or to establish whether or not a cement complies with a specification limit on early stiffening.  
5.2 When used for establishing compliance with a specification limit, the specification requirement is customarily stated in terms of the minimum allowable final penetration, in percent, calculated in accordance with the Calculation Section. When used for estimating the relative tendency of a cement to manifest early stiffening, additional information of value may be obtained if the remix procedure described in the Procedure Section is employed. Under some conditions, a judgment may be made by comparing the behavior in the initial test and in the remix procedure 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, as occurs in concrete pumping operations. It is most likely to be noticeable where concrete is mixed for a short period of time in stationary mixers and transported to the forms in non-agitating equipment, such 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 water to produce the same consistency, which may be expected to 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 o...
SCOPE
1.1 This test method covers the determination of early stiffening in hydraulic-cement paste.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health 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  
1.4 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.  
1.5 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: Historical
• Publication Date: 31-Jul-2019
• ICS: 91.100.10 - Cement. Gypsum. Lime. Mortar
• Technical Committee: C01 - Cement
• Drafting Committee: C01.30 - Time of Set

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: C451 − 19
Standard Test Method for
1
Early Stiffening of Hydraulic Cement (Paste Method)
This standard is issued under the fixed designation C451; 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* C219 Terminology Relating to Hydraulic Cement
C305 Practice for Mechanical Mixing of Hydraulic Cement
1.1 This test method covers the determination of early
Pastes and Mortars of Plastic Consistency
stiffening in hydraulic-cement paste.
C511 Specification for Mixing Rooms, Moist Cabinets,
1.2 The values stated in SI units are to be regarded as
Moist Rooms, and Water Storage Tanks Used in the
standard. No other units of measurement are included in this
Testing of Hydraulic Cements and Concretes
standard.
C670 Practice for Preparing Precision and Bias Statements
1.3 This standard does not purport to address all of the
for Test Methods for Construction Materials
safety concerns, if any, associated with its use. It is the
C1005 Specification for Reference Masses and Devices for
responsibility of the user of this standard to establish appro-
Determining Mass and Volume for Use in the Physical
priate safety and health practices and determine the applica-
Testing of Hydraulic Cements
bility of regulatory limitations prior to use.
D1193 Specification for Reagent Water
Warning:Fresh hydraulic-cementitiousmixturesarecaustic
and may cause chemical burns to skin and tissue upon
3. Terminology
2
prolonged exposure.
3.1 Definitions:
1.4 The text of this standard references notes and footnotes
3.1.1 early stiffening, n—the early development of stiffness
which provide explanatory material. These notes and footnotes
in the working characteristics of a hydraulic-cement paste,
(excluding those in tables and figures) shall not be considered
mortar, or concrete; varieties include false set and flash set.
as requirements of the standard.
3.1.2 false set, n—the early development of stiffness in the
1.5 This international standard was developed in accor-
working characteristics of a hydraulic-cement paste, mortar, or
dance with internationally recognized principles on standard-
concrete without the evolution of much heat, which stiffness
ization established in the Decision on Principles for the
can be dispelled and plasticity regained by further mixing
Development of International Standards, Guides and Recom-
without addition of water; also known as “grab set,” “prema-
mendations issued by the World Trade Organization Technical
ture stiffening,” “ hesitation set,” and “rubber set.”
Barriers to Trade (TBT) Committee.
3.1.3 flash set, n—the early development of stiffness in the
2. Referenced Documents
working characteristics of a hydraulic-cement paste, mortar, or
3
2.1 ASTM Standards:
concrete, usually with the evolution of considerable heat,
C150/C150M Specification for Portland Cement
which stiffness cannot be dispelled nor can the plasticity be
C183/C183M Practice for Sampling and the Amount of
regained by further mixing without addition of water; also
Testing of Hydraulic Cement
known as “quick set.”
C187 Test Method for Amount of Water Required for Nor-
3.1.4 Refer to Terminology C219 for definitions of other
mal Consistency of Hydraulic Cement Paste
terms.
1
This test method is under the jurisdiction ofASTM Committee C01 on Cement
4. Summary of Test Method
and is the direct responsibility of Subcommittee C01.30 on Time of Set.
Current edition approved Aug. 1, 2019. Published August 2019. Originally
4.1 A paste is prepared with the cement to be tested, using
approved in 1960. Last previous edition approved in 2018 as C451 – 18. DOI:
sufficient water to give a required initial penetration as mea-
10.1520/C0451-19.
2
sured by the Vicat apparatus at a stipulated time after comple-
Section on Safety, Manual of Cement Testing, Annual Book of ASTM
Standards, Vol 04.01.
tion of mixing. A second penetration, termed the final
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
penetration, is measured at a later stipulated time. The ratio of
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
final penetration to initial penetration is calculated as a
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. percentage.
*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
1

---------------------- Page: 1 ----------------------
C451 − 19
5. Significance and Use 6.6 Conical Ring, made of a rigid, non-corroding, no
...

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: C451 − 18 C451 − 19
Standard Test Method for
1
Early Stiffening of Hydraulic Cement (Paste Method)
This standard is issued under the fixed designation C451; 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 paste.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health 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
2
exposure.
1.4 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.
1.5 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
3
2.1 ASTM Standards:
C150/C150M Specification for Portland Cement
C183/C183M Practice for Sampling and the Amount of Testing of Hydraulic Cement
C187 Test Method for Amount of Water Required for Normal Consistency of Hydraulic Cement Paste
C219 Terminology Relating to Hydraulic Cement
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
C1005 Specification for Reference Masses and Devices for Determining Mass and Volume for Use in the Physical Testing of
Hydraulic Cements
D1193 Specification for Reagent Water
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.”
1
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, 2018Aug. 1, 2019. Published October 2018August 2019. Originally approved in 1960. Last previous edition approved in 20132018 as
C451 – 13.C451 – 18. DOI: 10.1520/C0451-18.10.1520/C0451-19.
2
Section on Safety, Manual of Cement Testing, Annual Book of ASTM Standards, Vol 04.01.
3
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
1

---------------------- Page: 1 ----------------------
C451 − 19
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.”
3.1.4 Refer to Terminology C219 for definitions of other terms.
4. Summary of Test Method
4.1 A paste is prepared with the cement to be tested, using sufficient water to give a required initial penetration as
...