ASTM C1372-23

Standard Specification for Dry-Cast Segmental Retaining Wall Units

ABSTRACT
This specification covers dry–cast segmental retaining wall units of concrete, machine–made from hydraulic cement, water, and suitable mineral aggregates with or without the inclusion of other materials. The units are intended for use in the construction of mortarless segmental retaining walls. The material composition of retaining wall units consists of cementitious materials like portland cement and its modified form, limestone, hydraulic cement, blended hydraulic cement, pozzolans, blast furnace slag cement, aggregates, and other constituents which include air-entraining agents, coloring pigments, integral water repellents, and finely ground silica. All units shall be sound and free of cracks or other defects that interfere with the proper placement of the unit or significantly impair the strength or permanence of the construction.
SCOPE
1.1 This specification covers dry-cast segmental retaining wall units of concrete, machine–made from hydraulic cement, water, and suitable mineral aggregates with or without the inclusion of other materials. The units are intended for use in the construction of mortarless segmental retaining walls.
Note 1: When particular features are desired, such as density classification, higher compressive strength, surface texture, finish, color, or other special features, such properties should be specified separately by the purchaser. Suppliers should be consulted as to availability of units having the desired features.  
1.2 The text of this standard references notes and footnotes that 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 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-2023
• ICS: 91.060.10 - Walls. Partitions. Facades
• Technical Committee: C15 - Masonry – Manufactured Masonry Units, Mortars and Grouts
• Drafting Committee: C15.03 - Concrete Masonry Units and Related Units

Relations

• Replaces: ASTM C1372-22 - Standard Specification for Dry-Cast Segmental Retaining Wall Units
• Effective Date: 01-Dec-2023
• Refers: ASTM C989/C989M-24 - Standard Specification for Slag Cement for Use in Concrete and Mortars
• Effective Date: 01-Feb-2024
• Refers: ASTM C1232-23 - Standard Terminology for Masonry
• Effective Date: 15-Dec-2023
• Refers: ASTM C140/C140M-23a - Standard Test Methods for Sampling and Testing Concrete Masonry Units and Related Units
• Effective Date: 01-Dec-2023
• Refers: ASTM C140/C140M-23 - Standard Test Methods for Sampling and Testing Concrete Masonry Units and Related Units
• Effective Date: 01-Jun-2023
• Refers: ASTM C989/C989M-22 - Standard Specification for Slag Cement for Use in Concrete and Mortars
• Effective Date: 01-Jul-2022
• Refers: ASTM C1232-21a - Standard Terminology for Masonry
• Effective Date: 01-Dec-2021
• Referred By: ASTM C1262/C1262M-18 - Standard Test Method for Evaluating the Freeze-Thaw Durability of Dry-Cast Segmental Retaining Wall Units and Related Concrete Units
• Effective Date: 01-Dec-2023

Overview

ASTM C1372-23: Standard Specification for Dry-Cast Segmental Retaining Wall Units defines the requirements for dry-cast concrete retaining wall units manufactured from hydraulic cement, water, and mineral aggregates. These units are intended specifically for use in constructing mortarless segmental retaining walls and are designed to deliver consistent performance, durability, and structural integrity. The standard is developed by ASTM International and incorporates internationally recognized principles of standardization.

The document outlines material specifications, physical properties, permissible variations, appearance criteria, and testing procedures for retaining wall units. By adhering to ASTM C1372-23, manufacturers, specifiers, and contractors can ensure that concrete retaining wall units meet strict quality and safety benchmarks.

Key Topics

• Material Requirements

  • Specifies allowable cementitious materials: portland cement, modified portland cement, blended hydraulic cement, pozzolans, blast furnace slag cement, and silica fume.
  • Aggregates must conform to established criteria, with flexibility for grading to suit production needs.
  • Integrally colored concrete pigments, air-entraining agents, and water repellents may be included if deemed suitable and non-detrimental to durability.

• Physical Properties

  • Units must be free of cracks or defects that interfere with installation or compromise strength and longevity.
  • Establishes minimum compressive strengths and allowable water absorption levels based on density classification (lightweight, medium, or normal weight).
  • Freeze-thaw durability is required in climates where repeated cycles are a concern, with detailed testing criteria provided.

• Dimensional Tolerances & Appearance

  • Strict limits on permissible dimensional variation for width, height, and length.
  • Surface quality standards are specified, including requirements for exposed faces regarding chips, cracks, texture, and color.

• Testing and Compliance

  • Specifies sampling and testing protocols for compressive strength, density, absorption, freeze-thaw durability, and dimensional tolerance.
  • Procedures for handling non-conforming units and shipment acceptance are detailed, promoting accountability between suppliers and purchasers.

Applications

ASTM C1372-23 is essential for:

• Landscape and Civil Engineering Projects
  Used for constructing gravity and reinforced segmental retaining walls that stabilize slopes, manage grade changes, create terraces, and provide erosion control.

• Infrastructure and Roadway Projects
  Employed in transportation and municipal works where retaining walls support highways, embankments, underpasses, and public spaces.

• Architectural Hardscaping
  Enables the creation of functional and aesthetic mortarless walls in residential, commercial, and public settings, offering flexibility in wall geometry, color, and texture.

• Quality Assurance and Procurement
  Provides a standardized reference for specifying, manufacturing, sampling, and testing retaining wall units, empowering project managers to procure high-quality concrete masonry units with documented performance criteria.

Related Standards

For broader context and compliance in construction and masonry, ASTM C1372-23 references and aligns with several other key ASTM standards, including:

• ASTM C33/C33M - Standard Specification for Concrete Aggregates
• ASTM C140/C140M - Test Methods for Sampling and Testing Concrete Masonry Units and Related Units
• ASTM C150/C150M - Standard Specification for Portland Cement
• ASTM C595/C595M - Standard Specification for Blended Hydraulic Cements
• ASTM C618 - Standard Specification for Coal Ash and Raw or Calcined Natural Pozzolan for Use in Concrete
• ASTM C979/C979M - Standard Specification for Pigments for Integrally Colored Concrete
• ASTM C989/C989M - Standard Specification for Slag Cement for Use in Concrete and Mortars
• ASTM C1240 - Standard Specification for Silica Fume Used in Cementitious Mixtures
• ASTM C1262/C1262M - Test Method for Evaluating the Freeze-Thaw Durability of Dry-Cast Segmental Retaining Wall Units and Related Concrete Units

By following ASTM C1372-23 and its referenced documents, professionals in the concrete products, construction, and civil engineering industries can consistently achieve safe, durable, and high-performing retaining wall installations. This specification supports sustainable and cost-effective solutions in both landscape and structural applications.

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: C1372 − 23
Standard Specification for
Dry-Cast Segmental Retaining Wall Units
This standard is issued under the fixed designation C1372; 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* Concrete Masonry Units
C595/C595M Specification for Blended Hydraulic Cements
1.1 This specification covers dry-cast segmental retaining
C618 Specification for Coal Ash and Raw or Calcined
wall units of concrete, machine–made from hydraulic cement,
Natural Pozzolan for Use in Concrete
water, and suitable mineral aggregates with or without the
C979/C979M Specification for Pigments for Integrally Col-
inclusion of other materials. The units are intended for use in
ored Concrete
the construction of mortarless segmental retaining walls.
C989/C989M Specification for Slag Cement for Use in
NOTE 1—When particular features are desired, such as density
Concrete and Mortars
classification, higher compressive strength, surface texture, finish, color,
C1157/C1157M Performance Specification for Hydraulic
or other special features, such properties should be specified separately by
Cement
the purchaser. Suppliers should be consulted as to availability of units
C1232 Terminology for Masonry
having the desired features.
C1240 Specification for Silica Fume Used in Cementitious
1.2 The text of this standard references notes and footnotes
Mixtures
that provide explanatory material. These notes and footnotes
C1262/C1262M Test Method for Evaluating the Freeze-
(excluding those in tables and figures) shall not be considered
Thaw Durability of Dry-Cast Segmental Retaining Wall
as requirements of the standard.
Units and Related Concrete Units
1.3 The values stated in inch-pound units are to be regarded
as standard. The values given in parentheses are mathematical
3. Terminology
conversions to SI units that are provided for information only
3.1 Terminology defined in Terminology C1232 shall apply
and are not considered standard.
for this specification.
1.4 This international standard was developed in accor-
3.2 Definitions:
dance with internationally recognized principles on standard-
3.2.1 Dry-cast, adj—manufacturing concrete products using
ization established in the Decision on Principles for the
low frequency, high amplitude vibration to consolidate con-
Development of International Standards, Guides and Recom-
crete of stiff or extremely dry consistency in a form.
mendations issued by the World Trade Organization Technical
3.2.2 segmental retaining wall unit, n—unit manufactured
Barriers to Trade (TBT) Committee.
of concrete for the construction of dry-stacked earth retaining
walls.
2. Referenced Documents
3.2.3 segmental retaining wall unit, dry-cast, n—a segmen-
2.1 ASTM Standards:
tal retaining wall unit manufactured of concrete using a
C33/C33M Specification for Concrete Aggregates
dry-cast process.
C140/C140M Test Methods for Sampling and Testing Con-
crete Masonry Units and Related Units
4. Materials
C150/C150M Specification for Portland Cement
C331/C331M Specification for Lightweight Aggregates for
4.1 Cementitious Materials—Cementitious materials shall
conform to the following applicable specifications:
4.1.1 Portland Cements—Specification C150/C150M.
This specification is under the jurisdiction of ASTM Committee C15 on
4.1.2 Modified Portland Cement—Portland cement con-
Manufactured Masonry Units and is the direct responsibility of C15.03 on Concrete
forming to Specification C150/C150M, modified as follows:
Masonry Units and Related Units.
(1) Limestone—If calcium carbonate is added to the
Current edition approved Dec. 1, 2023. Published December 2023. Originally
cement, the CaCO content shall not be less than 85 %.
approved in 1997. Last previous edition approved in 2022 as C1372 – 22. DOI:
10.1520/C1372-23.
(2) Limitation on Insoluble Residue—1.5 %.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
(3) Limitation on Air Content of Mortar—Volume percent,
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
22 % max.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. (4) Limitation on Loss of Ignition—7 %.
*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
C1372 − 23
4.1.3 Blended Hydraulic Cements—Specification C595/ adequate durability for the intended use. When testing is
C595M. required by the specifier to demonstrate freeze-thaw durability,
4.1.4 Hydraulic Cement—Specification C1157/C1157M. the units shall be tested in accordance with 8.3.
4.1.5 Pozzolans—Specification C618. 5.2.1 Specimens shall comply with either of the following:
4.1.6 Slag Cement—Specification C989/C989M. (1) the weight loss of each of five test specimens at the
4.1.7 Silica Fume—Specification C1240. conclusion of 100 cycles shall not exceed 1 % of its initial
weight; or (2) the weight loss of each of four of the five test
4.2 Aggregates—Aggregates shall conform to the following
specimens at the conclusion of 150 cycles shall not exceed
specifications, except for grading requirements:
1.5 % of its initial weight.
4.2.1 Normal Weight Aggregates—Specification C33/
C33M.
6. Permissible Variations in Dimensions
4.2.2 Lightweight Aggregates—Specification C331/C331M.
6.1 Overall dimensions for width, height, and length shall
NOTE 2—The grading requirements of Specifications C33/C33M and
differ by not more than 6 ⁄8 in. (3.2 mm) from the specified
C331/C331M may not be suitable for segmental retaining wall unit
standard dimensions.
production. Because of this, producers are allowed to modify grading to
meet their needs and the requirements of this specification.
NOTE 3—The term “width” refers to the horizontal dimension of the
unit measured perpendicular to the face of the wall from the exposed
4.3 Pigments for Integrally Colored Concrete—
surface of the unit to the back of the unit. The term “height” refers to the
Specification C979/C979M.
vertical dimension of the unit as placed in the wall. The term “length”
refers to the horizontal dimension of the unit measured parallel to the
4.4 Other Constituents—Air-entraining agents, integral wa-
running length of the wall.
ter repellents, and other constituents shall be previously estab-
6.1.1 Dimensional tolerance requirements for width shall be
lished as suitable for use in segmental retaining wall units and
waived for architectural surfaces.
shall conform to applicable ASTM standards or shall be shown
by test or experience to be not detrimental to the durability of
NOTE 4—Split-faced surfaces are the most common surfaces used to
the segmental retaining wall units or any material customarily
provide an architectural appearance to segmental retaining walls.
used in segmental retaining wall construction. However, other means could be used to obtain similar architectural effects
like tumbling, grinding, and slumping.
5. Physical Requirements
7. Finish and Appearance
5.1 At the time of delivery to the purchaser, units shall
7.1 Where units are to be used in exposed wall construction,
conform to the physical requirements of Table 1. Units shall be
the face or faces that are to be exposed shall not show chips or
free of defects that significantly impair the strength or perma-
cracks, except as permitted
...

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: C1372 − 22 C1372 − 23
Standard Specification for
Dry-Cast Segmental Retaining Wall Units
This standard is issued under the fixed designation C1372; 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 specification covers dry-cast segmental retaining wall units of concrete, machine–made from hydraulic cement, water,
and suitable mineral aggregates with or without the inclusion of other materials. The units are intended for use in the construction
of mortarless segmental retaining walls.
NOTE 1—When particular features are desired, such as density classification, higher compressive strength, surface texture, finish, color, or other special
features, such properties should be specified separately by the purchaser. Suppliers should be consulted as to availability of units having the desired
features.
1.2 The text of this standard references notes and footnotes that 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 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:
C33/C33M Specification for Concrete Aggregates
C140/C140M Test Methods for Sampling and Testing Concrete Masonry Units and Related Units
C150/C150M Specification for Portland Cement
C331/C331M Specification for Lightweight Aggregates for Concrete Masonry Units
C595/C595M Specification for Blended Hydraulic Cements
C618 Specification for Coal Ash and Raw or Calcined Natural Pozzolan for Use in Concrete
C979/C979M Specification for Pigments for Integrally Colored Concrete
C989/C989M Specification for Slag Cement for Use in Concrete and Mortars
C1157/C1157M Performance Specification for Hydraulic Cement
C1232 Terminology for Masonry
C1240 Specification for Silica Fume Used in Cementitious Mixtures
This specification is under the jurisdiction of ASTM Committee C15 on Manufactured Masonry Units and is the direct responsibility of C15.03 on Concrete Masonry
Units and Related Units.
Current edition approved Dec. 15, 2022Dec. 1, 2023. Published January 2023December 2023. Originally approved in 1997. Last previous edition approved in 20172022
as C1372 – 17.C1372 – 22. DOI: 10.1520/C1372-22.10.1520/C1372-23.
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
C1372 − 23
C1262/C1262M Test Method for Evaluating the Freeze-Thaw Durability of Dry-Cast Segmental Retaining Wall Units and
Related Concrete Units
3. Terminology
3.1 Terminology defined in Terminology C1232 shall apply for this specification.
3.2 Definitions:
3.2.1 Dry-cast, adj—manufacturing concrete products using low frequency, high amplitude vibration to consolidate concrete of
stiff or extremely dry consistency in a form.
3.2.2 segmental retaining wall unit, n—unit manufactured of concrete for the construction of dry-stacked earth retaining walls.
3.2.3 segmental retaining wall unit, dry-cast, n—a segmental retaining wall unit manufactured of concrete using a dry-cast
process.
4. Materials
4.1 Cementitious Materials—Materials Cementitious materials shall conform to the following applicable specifications:
4.1.1 Portland Cements—Specification C150/C150M.
4.1.2 Modified Portland Cement—Portland cement conforming to Specification C150/C150M, modified as follows:
(1) Limestone—If calcium carbonate is added to the cement, the CaCO content shall not be less than 85 %.
(2) Limitation on Insoluble Residue—1.5 %.
(3) Limitation on Air Content of Mortar—Volume percent, 22 % max.
(4) Limitation on Loss of Ignition—7 %.
4.1.3 Blended Hydraulic Cements—Specification C595/C595M.
4.1.4 Hydraulic Cement—Specification C1157/C1157M.
4.1.5 Pozzolans—Specification C618.
4.1.6 Blast Furnace Slag Cement—Specification C989/C989M.
4.1.7 Silica Fume—Specification C1240.
4.2 Aggregates—Aggregates shall conform to the following specifications, except for grading requirements:
4.2.1 Normal Weight Aggregates—Specification C33/C33M.
4.2.2 Lightweight Aggregates—Specification C331/C331M.
NOTE 2—The grading requirements of Specifications C33/C33M and C331/C331M may not be suitable for segmental retaining wall unit production.
Because of this, producers are allowed to modify grading to meet their needs and the requirements of this specification.
4.3 Pigments for Integrally Colored Concrete—Specification C979/C979M.
4.4 Other Constituents—Air-entraining agents, integral water repellents, and other constituents shall be previously established as
suitable for use in segmental retaining wall units and shall conform to applicable ASTM standards or shall be shown by test or
experience to be not detrimental to the durability of the segmental retaining wall units or any material customarily used in
segmental retaining wall construction.
C1372 − 23
5. Physical Requirements
5.1 At the time of delivery to the purchaser, units shall conform to the physical requirements of Table 1. Units shall be free of
defects that significantly impair the strength or permanence of the construction.
5.1.1 When higher compressive strengths than those listed in Table 1 are specified, the tested average net area compressive
strength of three units shall equal or exceed the specified compressive strength, and the following single unit strength requirements
shall apply.
5.1.1.1 When the specified compressive strength is less than 5000 psi, no single unit net area compressive strength test result shall
be less than the specified compressive strength minus 500 psi.
5.1.1.2 When the specified compressive strength is 5000 psi or greater, no single unit net area compressive strength test result shall
be less than 90 % of the specified compressive strength.
5.2 Freeze-Thaw Durability—In areas where repeated freezing and thawing under saturated conditions occur, freeze-thaw
durability shall be demonstrated by test or by proven field performance that the segmental retaining wall units have adequate
durability for the intended use. When testing is required by the specifier to demonstrate freeze-thaw durability, the units shall be
tested in accordance with 8.3.
5.2.1 Specimens shall comply with either of the following: (1) the weight loss of each of five test specimens at the conclusion of
100 cycles shall not exceed 1 % of its initial weight; or (2) the weight loss of each of four of the five test specimens at the
conclusion of 150 cycles shall not exceed 1.5 % of its initial weight.
6. Permissible Variations in Dimensio
...