ASTM C1691-21

Standard Specification for Unreinforced Autoclaved Aerated Concrete (AAC) Masonry Units

ABSTRACT
This specification addresses the dimensional tolerances, maximum limits for drying shrinkage, and shipping and handling requirements for solid unreinforced masonry units manufactured from autoclaved aerated concrete (AAC). The masonry units shall be composed entirely of AAC material and classified according to their strength class. The units shall conform to compressive strength, dry bulk density, and drying shrinkage requirements, which shall be determined in accordance with referenced ASTM documents.
SCOPE
1.1 This specification covers solid, unreinforced masonry units manufactured from autoclaved aerated concrete (AAC), a cementitious product. This specification addresses dimensional tolerances, maximum limits for drying shrinkage, and shipping and handling.  
1.2 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.  
1.3 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.

General Information

• Status: Published
• Publication Date: 30-Nov-2021
• ICS: 91.100.30 - Concrete and concrete products
• Technical Committee: C15 - Manufactured Masonry Units
• Drafting Committee: C15.10 - Autoclaved Aerated Concrete Masonry Units

Standards Content (Sample)

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.
Designation: C1691 −21
Standard Specification for
Unreinforced Autoclaved Aerated Concrete (AAC) Masonry
1
Units
This standard is issued under the fixed designation C1691; 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* 4. Classification
1.1 This specification covers solid, unreinforced masonry 4.1 AAC masonry units manufactured in accordance with
units manufactured from autoclaved aerated concrete (AAC), a this specification shall be classified according to their strength
cementitious product. This specification addresses dimensional class as specified in Specification C1693—AAC2, AAC3,
tolerances, maximum limits for drying shrinkage, and shipping AAC4, AAC5, or AAC6.
and handling.
NOTE 1—Typically, classes AAC2, ACC4, and ACC6 are predomi-
nantly used in masonry construction. Contact manufacturers for the
1.2 The values stated in inch-pound units are to be regarded
availability of all classes.
as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only
5. Materials and Manufacture
and are not considered standard.
5.1 AAC masonry units manufactured in accordance with
1.3 This standard does not purport to address all of the
this specification shall be composed entirely of AAC material
safety concerns, if any, associated with its use. It is the
conforming to Specification C1693.
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
6. Physical Requirements
mine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accor-
6.1 Compressive Strength—The compressive strength of the
dance with internationally recognized principles on standard-
units shall be determined according to Specification C1693 and
ization established in the Decision on Principles for the
shall conform to the requirements of Specification C1693 for
Development of International Standards, Guides and Recom-
the strength class in which the units are classified.
mendations issued by the World Trade Organization Technical
6.2 Dry Bulk Density—The dry bulk density shall be deter-
Barriers to Trade (TBT) Committee.
mined according to Specification C1693 and shall conform to
the requirements of Specification C1693 for the strength class
2. Referenced Documents
in which the units are classified.
2
2.1 ASTM Standards:
6.3 Drying Shrinkage—The drying shrinkage shall be deter-
C1232 Terminology for Masonry
mined in accordance with Specification C1693 and shall
C1693 Specification for Autoclaved Aerated Concrete
conform to the requirements of Specification C1693 for the
(AAC)
strength class in which the units are specified.
3. Terminology
7. Dimensions and Permissible Variations
3.1 Definitions—Terms defined in Terminology C1232 shall
7.1 The specified dimensions of the units shall be estab-
apply in this specification.
lished by the AAC unit manufacturer.
7.2 No overall unit dimension (width, height, or length)
1
shall differ by more than ⁄8 in. (3 mm) from the corresponding
1
This specification is under the jurisdiction of ASTM Committee C15 on
specified dimension
Manufactured Masonry Units and is the direct responsibility of Subcommittee
C15.10 on Autoclaved Aerated Concrete Masonry Units.
Current edition approved Dec. 1, 2021. Published December 2021. Originally
8. Visual Inspection
approved in 2009. Last previous edition approved in 2017 as C1391 – 11(2017).
DOI: 10.1520/C1691-21.
8.1 All units shall be sound and free of defects that would
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
interfere with the proper placing of the unit or impair the
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
strength or permanence of the construction. Minor imperfec-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. tions incidental to the usual methods of manufacture, or
*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 ----------------------
C1691 − 21
resulting from customary methods of handling in shipment and retained lot and tested. If the second set of specimens fails to
delivery, shall not be deemed grounds for rejection. conform to the test requirements, the
...

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: C1691 − 11 (Reapproved 2017) C1691 − 21
Standard Specification for
Unreinforced Autoclaved Aerated Concrete (AAC) Masonry
1
Units
This standard is issued under the fixed designation C1691; 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 Scope*
1.1 This specification covers solid, unreinforced masonry units manufactured from autoclaved aerated concrete (AAC), a
cementitious product. This specification addresses dimensional tolerances, maximum limits for drying shrinkage, and shipping and
handling.
1.2 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.
1.3 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
2.1 ASTM Standards:
C1232 Terminology for Masonry
C1693 Specification for Autoclaved Aerated Concrete (AAC)
3. Terminology
3.1 Definitions—Terms defined in Terminology C1232 shall apply in this specification.
4. Classification
4.1 AAC masonry units manufactured in accordance with this specification shall be classified according to their strength
class.class as specified in Specification C1693—AAC2, AAC3, AAC4, AAC5, or AAC6.
1
This specification is under the jurisdiction of ASTM Committee C15 on Manufactured Masonry Units and is the direct responsibility of Subcommittee C15.10 on
Autoclaved Aerated Concrete Masonry Units.
Current edition approved Dec. 1, 2017Dec. 1, 2021. Published January 2018December 2021. Originally approved in 2009. Last previous edition approved in 20112017
as C1391 – 11.C1391 – 11(2017). DOI: 10.1520/C1691-11R17.10.1520/C1691-21.
2
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 ----------------------
C1691 − 21
NOTE 1—Typically, classes AAC2, ACC4, and ACC6 are predominantly used in masonry construction. Contact manufacturers for the availability of all
classes.
5. Materials and Manufacture
5.1 AAC masonry units manufactured in accordance with this specification shall be composed entirely of AAC material
conforming to Specification C1693.
6. Physical Requirements
6.1 Compressive Strength—The compressive strength of the units shall be determined according to Specification C1693 and shall
conform to the requirements of Specification C1693 for the strength class in which the units are classified.
6.2 Dry Bulk Density—The dry bulk density shall be determined according to Specification C1693 and shall conform to the
requirements of Specification C1693 for the strength class in which the units are classified.
6.3 Drying Shrinkage—The drying shrinkage shall be determined in accordance with Specification C1693 and shall conform to
the requirements of Specification C1693 for the strength class in which the units are specified.
7. Dimensions and Permissible Variations
7.1 The specified dimensions of the units shall be established by the AAC unit manufacturer.
1
7.2 No overall unit dimension (width, height, or length) shall differ by more than ⁄8 in. (3 mm) from the corresponding specified
dimension
8. Visual Inspection
8.1 All units shall be sound and free of defects that would interfere with the proper placing of the unit or impair the strength or
permanence of the construction. Minor imperfections incidental to the usual methods of manufacture, or resulting fro
...