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    ASTM C451 - 19

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

    Active Standard ASTM C451 | Developed by Subcommittee: C01.30

    Book of Standards Volume: 04.01

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    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 of setting requirement.

    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 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.

    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    C150/C150M Specification for Portland 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

    ICS Code

    ICS Number Code 91.100.10 (Cement. Gypsum. Lime. Mortar)

    UNSPSC Code

    UNSPSC Code 30111601(Cement)

    Referencing This Standard
    Link Here
    Link to Active (This link will always route to the current Active version of the standard.)

    DOI: 10.1520/C0451-19

    Citation Format

    ASTM C451-19, Standard Test Method for Early Stiffening of Hydraulic Cement (Paste Method), ASTM International, West Conshohocken, PA, 2019, www.astm.org

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