ASTM C1738/C1738M-19

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Designation: C1738/C1738M − 18 C1738/C1738M − 19
Standard Practice for
High-Shear Mixing of Hydraulic Cement Pastes
This standard is issued under the fixed designation C1738/C1738M; 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 practice covers the high-shear mixing of hydraulic cement pastes.
1.2 The values stated in SI units or inch-pound units are to be regarded as the standard. Within the text, the inch-pound units
are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system shall be used
independently of the other. Combining values from the two systems may result in nonconformance with the 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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.4 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:
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
C1005 Specification for Reference Masses and Devices for Determining Mass and Volume for Use in the Physical Testing of
Hydraulic Cements
2.2 Non-ASTM Standard:
ANSI/API Recommended Practice 10B-2 (formerly 10B) Recommended Practice for Testing Well Cementsǁ
3. Terminology
3.1 Definitions—For definitions of terms used in this specification, refer to Terminology C219.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 mixing, high-shear, v—of pastes, the process of blending dry and liquid materials in a container using blades rotating
axially at speeds at or above 420 rad/s [4000 rpm].
4. Summary of Practice
4.1 The practice describes the mixing of hydraulic cement paste in a high-shear mixer with a cooling jacket or other method
to control the temperature of the paste. This procedure is derived from the ANSI/API standard and the following reports:
(1) R. Helmuth, L.M. Hills, D.A. Whiting, S. Bhattacharja, Abnormal Concrete Performance in the Presence of Admixtures,
RP333, Portland Cement Association, Skokie, Illinois, USA, 1995, 92 pages and
(2) C. F. Ferraris, Measurement of the rheological properties of cement paste: a New Approach, Int. RILEM Conf. —The role
of Admixtures in High Performance Concrete, ed. by J.G. Cabrera and R. Rivera-Villareal, Monterrey (Mexico), March 1999. pp.
333-342, or
This practice is under the jurisdiction of ASTM Committee C01 on Cement and is the direct responsibility of Subcommittee C01.22 on Workability.
Current edition approved May 1, 2018May 1, 2019. Published May 2018May 2019. Originally approved in 2011. Last previous edition approved in 20142018 as
C1738/C1738M – 14.C1738/C1738M – 18. DOI:10.1520/C1738_C1738M-18.DOI:10.1520/C1738_C1738M-19.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
*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
C1738/C1738M − 19
(3) C. Ferraris, K. Obla, R. Hill, The influence of mineral admixtures on the rheology of cement paste and concrete, Cement
and Concrete Research Vol. 31/2, pp. 245-255 (2001).
5. Significance and Use
5.1 This practice is useful in laboratory research on rheology of hydraulic cement systems as it has been shown to provide a
paste with rheological properties similar to those obtained in a concrete from which the aggregate had been removed. Mixing of
paste using C305 is not satisfactory as the paste is not thoroughly mixed, due to the absence of sand. In this practice the shear
imparted to the cement paste is significantly higher than in C305 and therefore it is known as high-shear mixing.
6. Apparatus
6.1 Mixer—Composed of an electrical motor, a mixing container and a tachometer with the motor speed controlled
automatically (rheostat adjustment of speed will not be acceptable). The blades are attached to the bottom of the container and
rotate axially. The power of the motor shall be sufficient to ensure that the speeds of the mixer loaded with 500.0 g [1.1 lb] of
cement and water shall maintain a preset rotational speed at 420 rad/s [4000 rpm] and 1047 rad/s [10 000 rpm]. The speed shall
be maintained within 5 % of the preset speeds.
NOTE 1—A variable speed mixer capable of controlling the speed by a feedback loop within a range of 0 rad/s [0 rpm] to 1360 rad/s [13 000 rpm]
is recommended. A mixer with a minimum of two speeds (420 rad/s [4000 rpm] and 1047 rad/s [10 000 rpm] loaded) preset either by the operator or
by the manufacturer is acceptable.
6.2 Cooling Unit—A water bath with an outside circulating option, capable of controlling the temperature to 61°C
[61°F]61 °C [61 °F] for the specified temperature range of 5-50°C [40-120°F] 5 to 50 °C [40 to 120°F] over the duration of the
test.
6.3 Mixing Container with the Blade Assembly —A 1-L [1 qt] container, lid and blade specifically designed for use with the
mixer motor. The blade assembly shall be constructed in such a manner that the blade can be removed for weighing and changing.
The blade shall be weighed initially and then periodically, replaced with a new blade when a 10 % mass loss has occurred. Replace
the blade if obvious blade deformation has occurred. If the mix temperature is to be controlled by a separate cooling unit, the
container shall also be equipped with a cooling system (see Note 2) that can be connected to the cooling unit.
NOTE 2—The cooling system could be either an integral part of the base of the container or a coil wrapped around the container.
6.4 Thermometers—A partial immersion thermometer readable 0.5°C [1°F]0.5 °C [1 °F] and accurate to 60.5°C
[61°F]60.5 °C [61 °F] when tested at 23°C [73°F]23 °C [73 °F] with a the range of 5 to 50°C50 °C [40 to 120°F].120 °F].
6.5 Cementitious Feeding System—A feeding system, capable of adding the total quantity of cementitious material into the
mixing container, within 60 s (see Note 3).
NOTE 3—A vibratory feeder or a lid mounted funnel is suitable for this purpose.
6.6 Timing Device—Stop watch or other suitable timing device accurate to 61 s when tested over a one-minute interval.
6.7 Top-Pan Balance—Complying with Specification
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