ASTM C744-21

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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: C744 − 16 C744 − 21
Standard Specification for
Prefaced Concrete and Calcium Silicate Masonry Units
This standard is issued under the fixed designation C744; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope*
1.1 This specification covers prefaced concrete and calcium silicate masonry units with the finished face(s) covered at the point
of manufacture with resin, resin and inert filler, or cement and inert filler to produce a smooth tile-like surface feature. This
specification does not address, and therefore is not applicable to, ground-face concrete masonry units that are manufactured by
grinding a thin layer off the surface of a concrete masonry unit to expose aggregates within and polishing to produce a smooth,
architectural finish.
1.2 The text of this specification 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.
1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered 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.
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:
C55 Specification for Concrete Building Brick
C73 Specification for Calcium Silicate Brick (Sand-Lime Brick)
C90 Specification for Loadbearing Concrete Masonry Units
C129 Specification for Nonloadbearing Concrete Masonry Units
C140C140/C140M Test Methods for Sampling and Testing Concrete Masonry Units and Related Units
C501 Test Method for Relative Resistance to Wear of Unglazed Ceramic Tile by the Taber Abraser
C1232 Terminology for Masonry
C1634 Specification for Concrete Facing Brick and Other Concrete Masonry Facing Units
This specification is under the jurisdiction of ASTM Committee C15 on Manufactured Masonry Units and is the direct responsibility of Subcommittee C15.03 on
Concrete Masonry Units and Related Units.
Current edition approved Feb. 1, 2016Dec. 1, 2021. Published February 2016December 2021. Originally approved in 1973. Last previous edition approved in 20142016
as C744 – 14.C744 – 16. DOI: 10.1520/C0744-16.10.1520/C0744-21.
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.
*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
C744 − 21
D822D822/D822M Practice for Filtered Open-Flame Carbon-Arc Exposures of Paint and Related Coatings
D2244 Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
D2486 Test Methods for Scrub Resistance of Wall Paints
E84 Test Method for Surface Burning Characteristics of Building Materials
3. Terminology
3.1 Terminology defined in Terminology C1232 shall apply for this specification.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 prefaced concrete masonry unit, n—a concrete masonry unit where the finished face(s) are covered at the point of
manufacture with either resin, resin and an inert filler, or cement and an inert filler to produce a smooth, tile-like surface feature.
3.2.1.1 Discussion—
Some prefaced units may also be referred to as glazed concrete masonry units.
3.2.2 prefaced calcium silicate masonry unit, n—a calcium silicate masonry unit where the finished face(s) are covered at the point
of manufacture with either resin, resin and an inert filler, or cement and an inert filler to produce a smooth, tile-like surface feature.
3.2.2.1 Discussion—
Some prefaced units may also be referred to as glazed calcium silicate masonry units.
4. Materials
4.1 Concrete masonry units on which prefaced surfaces are molded shall meet the requirements of:
4.1.1 Specification C55 for Concrete Building Brick.
4.1.2 Specification C90 for Loadbearing Concrete Masonry Units.
4.1.3 Specification C129 for Nonloadbearing Units.
4.1.4 Specification C1634 for Concrete Facing Brick and Other Concrete Masonry Facing Units.
4.2 Calcium silicate units on which prefaced surfaces are molded shall meet the requirements of Specification C73 for Calcium
Silicate Brick (Sand-Lime Brick).
NOTE 1—The purchaser of prefaced units should indicate the applicable specification and the type and grade of unit required. Where prefaced units are
required for exterior use, the manufacturer should be consulted for material suitable for this purpose.
5. Facing Requirements
5.1 Resistance to Crazing, Cracking, or Spalling—There shall be no crazing, cracking, or spalling of the facing material when the
unit is tested in accordance with 7.2.
5.2 Resistance to Chemicals—The condition of the surface shall show no change after testing with each of the chemicals listed
in 7.3.
5.3 Adhesion—When viewed without magnification, there shall be no failure of the adhesion of the facing material to the unit
subsequent to failure of the entire prefaced unit when tested in compression in accordance with 7.4.
5.4 Abrasion—The wear index shall exceed 130 when tested in accordance with 7.5.
5.5 Surface Burning Characteristics—When tested in accordance with 7.6, the surfaces of the prefaced units shall have a flame
spread classification not greater than 25 without evidence of continued progressive combustion and shall have a smoke density
rating not greater than 50.
5.6 Color, Tint, or Texture—Color, tint, or texture shall be as specified. When tested in accordance with 7.7 and then compared
with an unexposed unit, there shall be no change in texture, and color differences shall not exceed 5.0 Delta units.
C744 − 21
5.7 Soiling and Cleansability—There shall not be a stain visible when specimens are tested in accordance with 7.8.1 and then
viewed from a distance of 10 ft (3 m) under an illumination of not less than 50 fc (538.2 lm/m ) by an observer with normal vision.
Spotting media shall be observed to be completely removed from specimens when tested in accordance with 7.8.2 and 7.8.3 and
then viewed from a distance of 10 ft (3 m) under an illumination of not less than 50 fc (538.2 lm/m ) by an observer with normal
vision.
5.8 Report—Test reports shall show the results of tests required by 5.1 through 5.7.
6. Dimensional Tolerances
6.1 Face Dimension—The total variation from specified dimensions in the finished face dimensions of the units shall not exceed
6 ⁄16 in. (1.6 mm) from specified dimensions.
6.2 Distortion—The distortion of the plane and edges of the face of individual units from the corresponding plane surface and
edges of the unit
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