ASTM C451-99

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

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 the standard. The values given in parentheses are for information only.  
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.

General Information

• Status: Historical
• Publication Date: 09-Jan-1999
• ICS: 91.100.10 - Cement. Gypsum. Lime. Mortar
• Technical Committee: C01 - Cement
• Drafting Committee: C01.30 - Time of Set

Relations

• Replaced By: ASTM C451-04 - Standard Test Method for Early Stiffening of Hydraulic Cement (Paste Method)
• Effective Date: 01-Jan-2004
• Referred By: ASTM C1157/C1157M-23 - Standard Performance Specification for Hydraulic Cement
• Effective Date: 10-Jan-1999
• Referred By: ASTM C1222-23 - Standard Practice for Evaluation of Laboratories Testing Hydraulic Cement
• Effective Date: 10-Jan-1999
• Referred By: ASTM C688-22 - Standard Specification for Functional Additions for Use in Hydraulic Cements
• Effective Date: 10-Jan-1999
• Referred By: ASTM C150/C150M-22 - Standard Specification for Portland Cement
• Effective Date: 10-Jan-1999
• Referred By: ASTM C183/C183M-23 - Standard Practice for Sampling and the Amount of Testing of Hydraulic Cement
• Effective Date: 10-Jan-1999

Standards Content (Sample)

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: C 451 – 99
Standard Test Method for
Early Stiffening of Hydraulic Cement (Paste Method)
This standard is issued under the fixed designation C 451; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope D 1193 Specification for Reagent Water
1.1 This test method covers the determination of early
3. Terminology
stiffening in hydraulic-cement paste.
3.1 Definitions:
1.2 The values stated in SI units are to be regarded as the
3.1.1 early stiffening, n—the early development of stiffness
standard. The values given in parentheses are for information
in the working characteristics of a portland-cement paste,
only.
mortar, or concrete. Varieties include false set and flash set.
1.3 This standard does not purport to address all of the
3.1.2 false set, n—the early development of stiffness in the
safety concerns, if any, associated with its use. It is the
working characteristics of a portland-cement paste, mortar, or
responsibility of the user of this standard to establish appro-
concrete without the evolution of much heat, which stiffness
priate safety and health practices and determine the applica-
can be dispelled and plasticity regained by further mixing
bility of regulatory limitations prior to use. See Note 1 for a
without addition of water; also known as “grab set,” “prema-
specific warning statement.
ture stiffening,”“ hesitation set,” and “rubber set.”
NOTE 1—Warning: Fresh hydraulic cementitious mixtures are caustic
3.1.3 flash set, n—the early development of stiffness in the
and may cause chemical burns to skin and tissue upon prolonged
working characteristics of a portland-cement paste, mortar, or
exposure. The use of gloves, protective clothing, and eye protection is
concrete, usually with the evolution of considerable heat,
recommended. Wash contact area with copious amounts of water after
which stiffness cannot be dispelled nor can the plasticity be
contact. Wash eyes for a minimum of 15 min. Avoid exposure of the body
regained by further mixing without addition of water; also
to clothing saturated with the liquid phase of the unhardened material.
Remove contaminated clothing immediately after exposure. known as “quick set.”
2. Referenced Documents
4. Summary of Test Method
2.1 ASTM Standards:
4.1 A paste is prepared with the cement to be tested, using
C 150 Specification for Portland Cement
sufficient water to give a required initial penetration as mea-
C 183 Practice for Sampling and the Amount of Testing of
sured by the Vicat apparatus at a stipulated time after comple-
Hydraulic Cement
tion of mixing. A second penetration, termed the final penetra-
C 187 Test Method for Normal Consistency of Hydraulic
tion, is measured at a later stipulated time. The ratio of final
Cement
penetration to initial penetration is calculated as a percentage.
C 305 Practice for Mechanical Mixing of Hydraulic Cement
5. Significance and Use
Pastes and Mortars of Plastic Consistency
C 490 Practice for Use of Apparatus for the Determination 5.1 The purpose of this test method is to determine the
of Length Change of Hardened Cement Paste, Mortar, and
degree to which a cement paste develops early stiffening or to
Concrete establish whether or not a cement complies with a specification
C 670 Practice for Preparing Precision and Bias Statements
limit on early stiffening.
for Test Methods for Construction Materials 5.2 When used for establishing compliance with a specifi-
C 1005 Specification for Reference Masses and Devices for
cation limit, the specification requirement is customarily stated
Determining Mass for Use in the Physical Testing of in terms of the minimum allowable final penetration, in
Hydraulic Cements
percent, calculated in accordance with Section 11. When used
for estimating the relative tendency of a cement to manifest
early stiffening, additional information of value may be ob-
This test method is under the jurisdiction of ASTM Committee C-1 on Cement
tained if the remix procedure described in Section 10 is
and is the direct responsibility of Subcommittee C01.30 on Time of Set.
employed. Under some conditions, a judgment may be made
Current edition approved Jan. 10, 1999. Published May 1999. Originally
published as C 451 – 60 T. Last previous edition C 451 – 95.
Annual Book of ASTM Standards, Vol 04.01.
3 4
Annual Book of ASTM Standards, Vol 04.02. Annual Book of ASTM Standards, Vol 11.01.
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NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
C 451
by comparing the behavior in the initial test and in the remix 10.1.2 Introduce the materials for a batch into the bowl and
procedure to differentiate a relatively less serious and less mix in the following manner:
persistent tendency to early stiffening from one that is more
10.1.2.1 Place all the mixing water in the bowl.
persistent and, consequently, more serious.
10.1.2.2 Add the cement to the water and allow 30 s for the
5.3 Severe false setting in a cement may cause difficulty
water to absorb.
from a placing and handling standpoint, but it is not likely to
10.1.2.3 Start the mixer and mix at a slow speed (1406 5
cause difficulties where concrete is mixed for a longer time
r/min) for 30 s.
than usual, as usually occurs in transit mixing, or where it is
10.1.2.4 Stop the mixer for 15 s, and during this time scrape
remixed prior to placing or transporting, as occurs in concrete
down into the batch any paste that may have collected on the
pumping operations. It is most likely to be noticeable where
sides of the bowl.
concrete is mixed for a short period of time in stationary mixers
10.1.2.5 Start the mixer at a medium speed (285 610 r/min)
and transported to the forms in nonagitating equipment, such as
on some paving jobs. and mix for 2 ⁄2 min.
5.4 Cements with severe false setting usually require
10.2 Molding Test Specimens—Quickly form the cement
slightly more water to produce the same consistency, w
...