ASTM C1691-21
(Specification)Standard Specification for Unreinforced Autoclaved Aerated Concrete (AAC) Masonry Units
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
- Technical Committee
- C15 - Masonry – Manufactured Masonry Units, Mortars and Grouts
- Drafting Committee
- C15.10 - Autoclaved Aerated Concrete Masonry Units
Relations
- Effective Date
- 15-Dec-2023
- Effective Date
- 01-Jun-2017
- Effective Date
- 01-Jun-2017
- Effective Date
- 01-Sep-2015
- Effective Date
- 01-Jun-2015
- Effective Date
- 01-Jun-2012
- Effective Date
- 15-Jul-2011
- Effective Date
- 15-Dec-2010
- Effective Date
- 15-Jun-2010
- Effective Date
- 01-May-2010
- Effective Date
- 01-Jan-2010
- Effective Date
- 15-Dec-2009
- Effective Date
- 01-Oct-2009
- Effective Date
- 01-Oct-2009
- Effective Date
- 01-Jul-2009
Overview
ASTM C1691-21: Standard Specification for Unreinforced Autoclaved Aerated Concrete (AAC) Masonry Units sets forth the requirements for unreinforced, solid masonry units made entirely from autoclaved aerated concrete (AAC). Developed by ASTM International, this standard specifies dimensional tolerances, physical property limits, and shipping and handling guidelines for AAC masonry units. The intent is to ensure consistent quality and reliable performance of AAC products in building applications, facilitating their use in a wide range of construction projects.
Key Topics
Dimensional Tolerances:
The standard outlines permissible variations in width, height, and length for units, helping maintain proper fit and structural integrity. It establishes that unit dimensions must not deviate by more than 1/8 inch (3 mm) from specified measurements.Material Composition:
All units must be composed entirely of AAC material and comply with ASTM C1693 requirements, ensuring consistent product quality and safety.Physical Properties:
- Compressive Strength: Units are classified by strength class, in accordance with ASTM C1693.
- Dry Bulk Density: Must meet specific density thresholds for the relevant strength class.
- Drying Shrinkage: Maximum allowable shrinkage is clearly defined to prevent structural problems.
Sampling and Inspection:
Procedures for visual inspection, factory sampling, and purchaser verification protect end-users against defective or nonconforming products.Handling and Shipping:
The specification addresses recommended practices to minimize damage during handling, shipment, and delivery of AAC units.
Applications
Autoclaved aerated concrete (AAC) masonry units covered under ASTM C1691-21 are widely used in modern construction owing to their light weight, fire resistance, and superior thermal insulation properties. Common applications include:
Load-Bearing and Non-Load-Bearing Walls:
AAC blocks can be used for both structural and partition wall systems in residential, commercial, and industrial buildings.Fire Walls and Shaft Walls:
The fire-resistant nature of AAC units allows for safe and economic fire separation walls.Energy-Efficient Building Construction:
The thermal insulation properties of AAC contribute to energy efficiency, reducing heating and cooling costs.Prefabricated Components:
AAC units can be incorporated into prefabricated building elements such as panels and lintels.
ASTM C1691-21 ensures these AAC masonry units meet required performance standards for durability, consistency, and compatibility with building codes and specifications.
Related Standards
Several related ASTM standards provide important guidance for the testing, terminology, and classification of autoclaved aerated concrete masonry units:
- ASTM C1232 - Terminology for Masonry: Defines key terms and concepts relevant to masonry products and construction.
- ASTM C1693 - Specification for Autoclaved Aerated Concrete (AAC): Details further material property, testing, and classification requirements for AAC.
- Referenced International Standards: ASTM C1691-21 aligns with internationally recognized standardization principles in accordance with the WTO TBT Committee, supporting global trade and compliance.
Practical Value
Utilizing ASTM C1691-21 helps specifiers, manufacturers, contractors, and project owners ensure project compliance, achieve high quality construction results, and reduce risks associated with substandard materials. Adherence to the specification is essential for sustainable, high-performing, and safe masonry construction using AAC units. Frequent consultation of the latest edition is recommended to stay up to date with any revisions or changes that may impact use or compliance.
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Frequently Asked Questions
ASTM C1691-21 is a technical specification published by ASTM International. Its full title is "Standard Specification for Unreinforced Autoclaved Aerated Concrete (AAC) Masonry Units". This standard covers: 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.
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.
ASTM C1691-21 is classified under the following ICS (International Classification for Standards) categories: 91.100.30 - Concrete and concrete products. The ICS classification helps identify the subject area and facilitates finding related standards.
ASTM C1691-21 has the following relationships with other standards: It is inter standard links to ASTM C1232-23, ASTM C1693-11(2017), ASTM C1232-17, ASTM C1232-15a, ASTM C1232-15, ASTM C1232-12, ASTM C1693-11, ASTM C1232-10c, ASTM C1232-10b, ASTM C1232-10a, ASTM C1232-10, ASTM C1232-09b, ASTM C1693-09, ASTM C1693-09e1, ASTM C1232-09a. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
ASTM C1691-21 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
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
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.
2.1 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)
shall differ by more than ⁄8 in. (3 mm) from the corresponding
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, 202
...
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
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
2.1 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.
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.
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
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 Bu
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