ASTM C652-22

Standard Specification for Hollow Brick (Hollow Masonry Units Made From Clay or Shale)

ABSTRACT
This specification covers hollow building brick and hollow facing brick made from clay, shale, fire clay, or mixtures thereof, and fired to incipient fusion. Hollow brick shall be understood to mean hollow clay masonry units whose net cross-sectional area (solid area) in any plane parallel to the surface, containing the cores, cells, or deep frogs, is less than 75 % of its gross cross-sectional area measured in the same plane. The bricks are manufactured from clay, shale, or similar naturally occurring substances and subjected to a heat treatment at elevated temperatures (firing). The heat treatment shall develop sufficient fired bond between the particulate constituents to provide the strength and durability requirements specified. Bricks that are colored by flashing or textured by sanding, where sand does not form a continuous coating, shall not be considered as surface-colored brick. Hollow bricks require greater shell and web thicknesses and higher minimum compressive strength than structural clay tile, but permit greater void area and lesser distance from exposed edge to core hole than solid brick. Therefore, environmental and structural performance may be different in elements constructed of hollow brick from those constructed of structural clay tile or solid brick. The hollow bricks can be classified into Grades SW and MW according to their degree of resistance to frost action and disintegration by weathering. According to their physical properties, the bricks can be classified into Types HBS, HBX, HBA, and HBB. In terms of size of void areas or hollow spaces, the bricks can be designated into Classes H40V and H60V. The brick shall be free of defects, deficiencies, and surface treatments, including coatings, that would interfere with the proper laying of the brick or significantly impair the strength or performance of the construction. Physical properties like compressive strength, water absorption, saturation coefficient, breakage, and cracks shall be determined.
SCOPE
1.1 This specification covers hollow building brick and hollow facing brick made from clay, shale, fire clay, or mixtures thereof, and fired to incipient fusion; intended for use in masonry supplying structural and/or facing components to the structure. In this specification, the term hollow brick shall be understood to mean hollow clay masonry units whose net cross-sectional area (solid area) in any plane parallel to the surface containing the cores, cells, or deep frogs, is less than 75 % of its gross cross-sectional area measured in the same plane (see 4.3).  
1.2 The requirements of this specification apply at the time of purchase. The use of results from testing of brick extracted from masonry structures for determining compliance with the requirements of this specification is beyond the intent of this standard.  
1.3 This specification does not cover brick intended for use as paving brick (see Specification C902).  
1.4 Brick covered by this specification are ceramic products manufactured primarily from clay, shale, or similar naturally occurring substances and subjected to a heat treatment at elevated temperatures (firing). The heat treatment shall develop sufficient fired bond between the particulate constituents to provide the strength and durability requirements of this specification. Additives or recycled materials are permitted to be included at the option of the manufacturer. (See “firing” and “firing bond” in Terminology C1232.)  
1.4.1 This specification and its individual requirements shall not be used to qualify or corroborate the performance of a masonry unit made from other materials, or made with other forming methods, or other means of binding the materials.  
1.5 Four types of hollow brick in each of two grades and two classes are covered.  
1.6 Hollow brick differ from unglazed structural clay tile (Specifications C34 and C212) and solid brick (Specifications C62 and C216). Hollow brick require greater...

General Information

• Status: Published
• Publication Date: 31-May-2022
• ICS: 91.100.15 - Mineral materials and products
• Technical Committee: C15 - Masonry – Manufactured Masonry Units, Mortars and Grouts
• Drafting Committee: C15.02 - Brick and Structural Clay Tile

Relations

• Refers: ASTM C1232-23 - Standard Terminology for Masonry
• Effective Date: 15-Dec-2023
• Refers: ASTM C67/C67M-19 - Standard Test Methods for Sampling and Testing Brick and Structural Clay Tile
• Effective Date: 01-Jul-2019
• Refers: ASTM C67/C67M-18 - Standard Test Methods for Sampling and Testing Brick and Structural Clay Tile
• Effective Date: 01-Feb-2018
• Refers: ASTM C216-17a - Standard Specification for Facing Brick (Solid Masonry Units Made from Clay or Shale)
• Effective Date: 01-Oct-2017
• Refers: ASTM C1232-17 - Standard Terminology for Masonry
• Effective Date: 01-Jun-2017
• Refers: ASTM C212-17 - Standard Specification for Structural Clay Facing Tile
• Effective Date: 01-Jun-2017
• Refers: ASTM C216-17 - Standard Specification for Facing Brick (Solid Masonry Units Made from Clay or Shale)
• Effective Date: 15-Mar-2017
• Refers: ASTM C216-16 - Standard Specification for Facing Brick (Solid Masonry Units Made from Clay or Shale)
• Effective Date: 01-Jun-2016
• Refers: ASTM C1232-15a - Standard Terminology of Masonry
• Effective Date: 01-Sep-2015
• Refers: ASTM C1232-15 - Standard Terminology of Masonry
• Effective Date: 01-Jun-2015
• Refers: ASTM C216-15 - Standard Specification for Facing Brick (Solid Masonry Units Made from Clay or Shale)
• Effective Date: 01-Feb-2015
• Refers: ASTM C216-14 - Standard Specification for Facing Brick (Solid Masonry Units Made from Clay or Shale)
• Effective Date: 01-Feb-2014
• Refers: ASTM C902-14 - Standard Specification for Pedestrian and Light Traffic Paving Brick
• Effective Date: 01-Feb-2014
• Refers: ASTM C212-14 - Standard Specification for Structural Clay Facing Tile
• Effective Date: 01-Feb-2014
• Refers: ASTM C212-13 - Standard Specification for Structural Clay Facing Tile
• Effective Date: 15-Dec-2013

Overview

ASTM C652-22: Standard Specification for Hollow Brick (Hollow Masonry Units Made From Clay or Shale) establishes the criteria for hollow building brick and hollow facing brick. These bricks are manufactured primarily from clay, shale, fire clay, or mixtures thereof, and are fired to achieve required strength and durability. Hollow brick, as defined by this standard, are clay masonry units with a net cross-sectional area (solid area) of less than 75% of the gross cross-sectional area in any plane parallel to the surface containing cores, cells, or deep frogs.

This specification ensures that hollow masonry units meet strict requirements for physical properties, dimensions, durability, and appearance, making them suitable for use in structural and facing components in masonry construction. It does not apply to solid brick or paving brick.

Key Topics

• Material composition and manufacturing
  Hollow brick covered by ASTM C652-22 are ceramic products formed from clay, shale, or similar materials and fired at high temperatures. Additives or recycled materials may be incorporated as allowed by the manufacturer.

• Classification

  • Grade: Based on resistance to freeze/thaw damage
    • Grade SW (Severe Weathering): Intended for areas with high freeze/thaw exposure
    • Grade MW (Moderate Weathering): For regions with moderate freeze/thaw exposure
  • Type: Four types to specify dimensional tolerance, appearance, and surface finish
    • Type HBS: General use
    • Type HBX: High precision requirements
    • Type HBA: Architectural effects
    • Type HBB: No specific requirements for appearance
  • Class: Defined by the size of void areas
    • Class H40V: 25-40% void area
    • Class H60V: 40-60% void area

• Physical properties
  Requirements apply at the time of purchase and include:

  • Minimum compressive strength
  • Maximum water absorption
  • Saturation coefficient
  • Limits on breakage, cracks, and appearance defects

• Dimension and tolerance
  Maximum permissible variations in size and warpage are prescribed to ensure consistency.

• Appearance
  Hollow brick must be free from defects or treatments that impair laying or performance. Chips, cracks, color, and texture are regulated and may be specified by the purchaser.

Applications

• Structural Masonry:
  ASTM C652-22 hollow bricks offer a lightweight alternative for load-bearing and non-load-bearing walls, combining structural integrity with reduced weight, which eases handling and installation.

• Architectural Facing:
  Hollow facing bricks provide aesthetically appealing finishes due to customizable color and texture options, while meeting structural and durability requirements.

• Energy Efficiency:
  The hollow design contributes to improved thermal performance by increasing wall insulation properties.

• Versatility:
  With various grades, types, and classes, these bricks can be specified for a wide range of building types and geographic conditions, including areas with severe weather exposure.

Related Standards

For alignment and comprehensive compliance in masonry construction, consider the following related ASTM standards:

• ASTM C34: Specification for Structural Clay Loadbearing Wall Tile
• ASTM C62: Specification for Building Brick (Solid Masonry Units)
• ASTM C216: Specification for Facing Brick (Solid Masonry Units)
• ASTM C212: Specification for Structural Clay Facing Tile
• ASTM C902: Specification for Pedestrian and Light Traffic Paving Brick
• ASTM C67/C67M: Test Methods for Sampling and Testing Brick and Structural Clay Tile
• ASTM C1232: Terminology for Masonry

These standards, when used in conjunction with ASTM C652-22, help ensure comprehensive quality, durability, and performance of masonry structures.

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Keywords: ASTM C652-22, hollow brick, clay masonry units, shale masonry units, brick specification, structural masonry, facing brick, masonry durability, brick physical properties, hollow masonry standards

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:C652 −22
Standard Specification for
Hollow Brick (Hollow Masonry Units Made From Clay or
Shale)
This standard is issued under the fixed designation C652; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber 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* 1.6 Hollow brick differ from unglazed structural clay tile
(Specifications C34 and C212) and solid brick (Specifications
1.1 This specification covers hollow building brick and
C62 and C216). Hollow brick require greater shell and web
hollow facing brick made from clay, shale, fire clay, or
thicknesses and higher minimum compressive strength than
mixtures thereof, and fired to incipient fusion; intended for use
structural clay tile, but permit greater void area and lesser
in masonry supplying structural and/or facing components to
distance from exposed edge to core hole than solid brick.
the structure. In this specification, the term hollow brick shall
Therefore, environmental and structural performance may be
be understood to mean hollow clay masonry units whose net
different in elements constructed of hollow brick from those
cross-sectional area (solid area) in any plane parallel to the
constructed of structural clay tile or solid brick.
surface containing the cores, cells, or deep frogs, is less than
75% of its gross cross-sectional area measured in the same 1.7 The text of this specification references notes and
plane (see 4.3). footnotes which provide explanatory material.These notes and
footnotes (excluding those in tables and figures) shall not be
1.2 The requirements of this specification apply at the time
considered as requirements of the specification.
of purchase. The use of results from testing of brick extracted
from masonry structures for determining compliance with the 1.8 The values stated in inch-pound units are to be regarded
requirements of this specification is beyond the intent of this as standard. The values given in parentheses are mathematical
standard. conversions to SI units that are provided for information only
and are not considered standard.
1.3 This specification does not cover brick intended for use
1.9 This international standard was developed in accor-
as paving brick (see Specification C902).
dance with internationally recognized principles on standard-
1.4 Brickcoveredbythisspecificationareceramicproducts
ization established in the Decision on Principles for the
manufactured primarily from clay, shale, or similar naturally
Development of International Standards, Guides and Recom-
occurring substances and subjected to a heat treatment at
mendations issued by the World Trade Organization Technical
elevatedtemperatures(firing).Theheattreatmentshalldevelop
Barriers to Trade (TBT) Committee.
sufficient fired bond between the particulate constituents to
provide the strength and durability requirements of this speci-
2. Referenced Documents
fication. Additives or recycled materials are permitted to be
2.1 ASTM Standards:
included at the option of the manufacturer. (See “firing” and
C34Specification for Structural Clay LoadbearingWallTile
“firing bond” in Terminology C1232.)
C62Specification for Building Brick (Solid Masonry Units
1.4.1 Thisspecificationanditsindividualrequirementsshall
Made From Clay or Shale)
not be used to qualify or corroborate the performance of a
C67/C67MTest Methods for Sampling and Testing Brick
masonry unit made from other materials, or made with other
and Structural Clay Tile
forming methods, or other means of binding the materials.
C212Specification for Structural Clay Facing Tile
1.5 Four types of hollow brick in each of two grades and
C216Specification for Facing Brick (Solid Masonry Units
two classes are covered.
Made from Clay or Shale)
C902Specification for Pedestrian and Light Traffic Paving
Brick
This specification is under the jurisdiction of ASTM Committee C15 on
Manufactured Masonry Units and is the direct responsibility of Subcommittee
C15.02 on Brick and Structural Clay Tile. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved June 1, 2022. Published June 2022. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1970. Last previous edition approved in 2021 as C652–21. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/C0652-22. 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
C652−22
C1232Terminology for Masonry shall comply with the requirements of Section 11 on Coring
and Frogging and to the minimum requirements contained in
Table 1 (see Fig. 1).
3. Terminology
4.3.3 When the class is not specified, the requirements of
3.1 Definitions—For definitions relating to masonry and
Class H40V shall govern.
hollow brick, refer to Terminology C1232.
5. Ordering Information
4. Classification
5.1 Orders for hollow brick under this specification shall
4.1 Grades—Grades classify brick according to their resis-
include the following information:
tance to damage by freezing and thawing when saturated at a
5.1.1 Grade (4.1)—Grade SW governs when grade is not
moisturecontentnotexceedingthe24-hcoldwaterabsorption.
specified.
Two grades of hollow brick are covered and the requirements
5.1.2 Type (4.2)—Type HBS governs when type is not
are given in Section 7.
specified.
5.1.3 Class (4.3)—Specify Class H40V or H60V. or accept
NOTE 1—Although grade is associated with resistance to deterioration
Class H40V governs if Class is not specified.
under freeze/thaw exposures, freeze/thaw resistance of a clay brick unit is
also affected by the properties of the surrounding materials, the construc- 5.1.4 Size (9.1)—Specify size of brick, width by height by
tion details, and the overall environment in which the clay unit is placed;
length.
each of which may influence exposure to moisture and freezing condi-
5.1.4.1 For Type HBA, specify tolerances on dimensions
tions. Brick masonry should be detailed to minimize saturation or
(9.1), warpage (9.2), or approve a designated sample.
near-saturation of the units in freezing conditions. Measurement of
5.1.5 Color, color range, and texture (10.5) by approving a
moisture content of brick in buildings indicates that, when the building is
designed and constructed to reduce water penetration, the 24-h cold water
sample.
absorption is unlikely to be exceeded. See Specification C216, Appendix
5.1.5.1 ForTypeHBB,color,colorrangeandtexturearenot
for additional information regarding freeze/thaw durability in service.
required.
4.1.1 Grade SW (Severe Weathering)—Hollow brick in- 5.1.6 Finish on more than one face and one end (10.6).
tended for use where high resistance to damage caused by
5.1.7 Sampling (12.2)—Place(s) of selection for test speci-
cyclic freezing and thawing is desired. mens.
4.1.2 Grade MW (Moderate Weathering)—Hollow brick
5.2 Orders for hollow brick under this specification may
intended for use where moderate resistance to cyclic freezing
include the following information:
and thawing damage is permissible.
5.2.1 Strength (7.2)—Specify only if above minimum com-
pressive strength in Table 2.
4.2 Types—Four types of hollow brick are covered:
5.2.2 Special Shapes (10.6)—Specify size, dimensions and
4.2.1 Type HBS—Hollow brick for general use in masonry.
finished faces by approved shop drawing or other means.
4.2.2 Type HBX—Hollow brick for general use in masonry
5.2.3 Frogging (10.5)—Frog permitted in one bearing sur-
where a higher degree of precision and lower permissible
face if not specified.
variation in size than permitted for Type HBS is required.
5.2.4 Costs of Tests (Note 11)—Party who will pay and
4.2.3 Type HBA—Hollow brick for general use in masonry
conditions of payment of compliance testing.
selected to produce characteristic architectural effects resulting
NOTE 2—See 6.3 and Section 7 for optional information.
from nonuniformity in size and texture of the individual units.
4.2.4 Type HBB—Hollow brick for general use in masonry
6. Materials and Manufacture
whereaparticularcolor,texture,finish,uniformity,orlimitson
cracks, warpage, or other imperfections detracting from the 6.1 The body of all hollow brick shall be of clay, shale, fire
clay, or mixtures of these materials, with or without
appearance are not a consideration.
admixtures, burned to meet the requirements of this specifica-
4.2.5 When the type is not specified, the requirements for
tion.Any coloring or other materials added to the clay shall be
Type HBS shall govern.
suitable ceramic materials and shall be well distributed
4.3 Class—Two classes of hollow brick are covered:
throughout the body.
4.3.1 Class H40V—Hollow brick intended for use where
6.2 Colors and textures produced by application of inor-
void areas or spaces greater than 25%, but not greater than
ganic coatings to the finished face(s) of the brick shall be
40%, of the gross cross-sectional area of the unit measured in
any plane parallel to the surface containing the cores, cells, or
deep frogs are desired. The void spaces, the web thicknesses,
TABLE 1 Class H60V—Hollow Brick Minimum Thickness
andtheshellthicknessesshallcomplywiththerequirementsof
of Face Shells and Webs, in. (mm)
Section 11 on Coring and Frogging.
Face Shell Thicknesses
End Shells or
4.3.2 Class H60V—Hollow brick intended for use where
Nominal Width of Units
Cored or Double
End Webs
Solid
larger void areas are desired.The sum of these void areas shall Shell
3 3
be greater than 40%, but not greater than 60%, of the gross 3 and 4 (76 and 101) ⁄4 (19.05) . ⁄4 (19.05)
6 (152) 1 (25.4) 1 ⁄2 (38) 1 (25.4)
cross-sectional area of the unit measured in any plane parallel
1 1
8 (203) 1 ⁄4 (32) 1 ⁄2 (38) 1 (25.4)
to the surface containing the cores, cells or deep frogs. The
1 5
10 (254) and greater 1 ⁄4 (32) 1 ⁄8 (41) 1 (25.4)
void spaces, the web thicknesses, and the shell thicknesses
C652−22
FIG. 1 Hollow Brick Units
TABLE 2 Physical Requirements NOTE 3—When surface colored brick, other than sanded or flashed, are
specified for exterior use, the purchaser should require that data be
Compressive Strength Water Absorption Saturation
submitted showing that after 50 cycles of freezing thawing there is no
gross area, min, psi by 5-h Coefficient,
Desig-
observabledifferenceintheappliedfinishwhenviewedfromadistanceof
(MPa) Boiling, max, % max
nation
Average of Average Indi- Average Indi- 10 ft (3.0 m) under an illumination of not less than 50 ft-candles (538 lx)
Individual
5 brick of 5 brick vidual of 5 brick vidual
by an observer with normal vision.
Grade SW 3000 (20.7) 2500 (17.2) 17.0 20.0 0.78 0.80
Service records of the performance of the particular coated brick in
Grade MW 2500 (17.2) 2200 (15.2) 22.0 25.0 0.88 0.90
exterior locations may be accepted in place of the freezing and thawing
test, upon consent of the purchaser.
6.3 The brick shall be free of defects, deficiencies, and
permitted with the consent of the purchaser, provided that
surface treatments, including coatings, that would interfere
evidence is furnished of the durability of the coatings. Brick
with the proper laying of the brick or significantly impair the
that are colored by flashing or textured by sanding, where the
strength or performance of the construction.
sand does not form a continuous coating, shall not be consid-
ered as surface-colored brick for the purpose of this specifica- 6.4 If any post-firing coatings or surface treatments are
tion. applied by the manufacturer, the manufacturer shall report the
C652−22
type and extent of these coatings or surface treatments in all described in the Rating Section of the Freezing and Thawing
certificates of compliance with this specification. test procedures of Test Methods C67/C67M.
NOTE 4—The 50-cycle freezing and thawing test is used as an
7. Physical Properties
alternative only when the brick do not conform to either Table 2
requirements for maximum water absorption and saturation coefficient, or
7.1 Durability—When grade is not specified, the require-
to the requirements of the Absorption Alternate in 7.1.2.
ments for Grade SW shall govern.
7.1.1 Physical Property Requirements—Thebrickshallcon- 7.1.3.1 Grade SW: Breakage and Weight Loss
form to the physical requirements for the grade specified as Requirement—No individual unit separates or disintegrates
prescribed in Table 2. For the compressive strength require- resulting in a weight loss greater than 0.5% of its original dry
ments in Table 2, test the unit with the compressive force weight.
perpendiculartothebedsurfaceoftheunit,withtheunitinthe 7.1.3.2 Grade SW: Cracking Requirement—No individual
stretcher position. unit develops a crack that exceeds, in length, the unit’s least
7.1.2 Absorption Alternate—The saturation coefficient re- dimension.
quirement does not apply, provided that the 24-h cold water 7.1.4 Low Weathering Index Alternative:
absorption of each of the five units tested does not exceed
7.1.4.1 If the brick are intended for use exposed to weather
8.0%. where the weathering index is less than 50 (see Fig. 2), and
7.1.3 Freezing and Thawing Alternative—The requirements
unless otherwise specified, the requirements given in Table 2
for 5-h boiling water absorption and saturation coefficient do for 5-h boiling water absorption and for saturation coefficient
notapply,providedasampleoffivebrick,meetingthestrength shallnotapply,buttheminimumaveragecompressivestrength
requirementsofTable2,passesthefreezingandthawingtestas requirement of 2500 psi (17.2 MPa) shall apply.
Grade Recommendations for Face Exposures
Weathering Index (Note 5)
Exposure
Less than 50 50 and greater
In vertical surfaces:
In contact with earth SW or MW SW
Not in contact with earth SW or MW SW
In other than vertical surfaces:
In contact with earth SW SW
Not in contact with earth SW or MW SW
FIG. 2Weathering Indices in the United States
C652−22
NOTE 5—The effect of weathering on brick is related to the weathering
C67/C67M, and a rating for efflorescence shall be “not
index, which for any locality is the product of the average annual number
effloresced.” If the rating for efflorescence is “effloresced,” the
of freezing cycle days and the average annual winter rainfall in inc
...

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: C652 − 21 C652 − 22
Standard Specification for
Hollow Brick (Hollow Masonry Units Made From Clay or
Shale)
This standard is issued under the fixed designation C652; 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 hollow building brick and hollow facing brick made from clay, shale, fire clay, or mixtures thereof,
and fired to incipient fusion; intended for use in masonry and supplying structural and/or facing components to the structure. In
this specification, the term hollow brick shall be understood to mean hollow clay masonry units whose net cross-sectional area
(solid area) in any plane parallel to the surface,surface containing the cores, cells, or deep frogs, is less than 75 % of its gross
cross-sectional area measured in the same plane (see 4.3).
1.2 The property requirements of this specification apply at the time of purchase. The use of results from testing of brick extracted
from masonry structures for determining conformance or nonconformance to the property requirements (Section compliance with
the requirements 7) of this standardspecification is beyond the scopeintent of this specification. standard.
1.3 This specification does not cover brick intended for use as paving brick (see Specification C902).
1.4 Brick covered by this specification are ceramic products manufactured primarily from clay, shale, or similar naturally
occurring substances and subjected to a heat treatment at elevated temperatures (firing). The heat treatment shall develop sufficient
fired bond between the particulate constituents to provide the strength and durability requirements of this specification. Additives
or recycled materials are permitted to be included at the option of the manufacturer. (See “firing” and “firing bond” in Terminology
C1232.)
1.4.1 This specification and its individual requirements shall not be used to qualify or corroborate the performance of a masonry
unit made from other materials, or made with other forming methods, or other means of binding the materials.
1.5 Four types of hollow brick in each of two grades and two classes are covered.
1.6 Hollow brick differ from unglazed structural clay tile (Specifications C34 and C212) and solid brick (Specifications C62 and
C216). Hollow brick require greater shell and web thicknesses and higher minimum compressive strength than structural clay tile,
but permit greater void area and lesser distance from exposed edge to core hole than solid brick. Therefore, environmental and
structural performance may be different in elements constructed of hollow brick from those constructed of structural clay tile or
solid brick.
This specification is under the jurisdiction of ASTM Committee C15 on Manufactured Masonry Units and is the direct responsibility of Subcommittee C15.02 on Brick
and Structural Clay Tile.
Current edition approved June 1, 2021June 1, 2022. Published June 2021June 2022. Originally approved in 1970. Last previous edition approved in 20192021 as
C652 – 19b.C652 – 21. DOI: 10.1520/C0652-21.10.1520/C0652-22.
*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
C652 − 22
1.7 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 specification.
1.8 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.
1.9 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:
C34 Specification for Structural Clay Loadbearing Wall Tile
C62 Specification for Building Brick (Solid Masonry Units Made From Clay or Shale)
C67/C67M Test Methods for Sampling and Testing Brick and Structural Clay Tile
C212 Specification for Structural Clay Facing Tile
C216 Specification for Facing Brick (Solid Masonry Units Made from Clay or Shale)
C902 Specification for Pedestrian and Light Traffic Paving Brick
C1232 Terminology for Masonry
3. Terminology
3.1 Definitions—For definitions relating to masonry and hollow brick, refer to Terminology C1232.
4. Classification
4.1 Grades—Grades classify brick according to their resistance to damage by freezing and thawing when saturated at a moisture
content not exceeding the 24-h cold water absorption. Two grades of hollow brick are covered and the requirements are given in
Section 7.
NOTE 1—Although grade is associated with resistance to deterioration under freeze/thaw exposures, freeze/thaw resistance of a clay brick unit is also
affected by the properties of the surrounding materials, the construction details, and the overall environment in which the clay unit is placed; each of which
may influence exposure to moisture and freezing conditions. Brick masonry should be detailed to minimize saturation or near-saturation of the units in
freezing conditions. Measurement of moisture content of brick in buildings indicates that, when the building is designed and constructed to reduce water
penetration, the 24-h cold water absorption is unlikely to be exceeded. See Specification C216, Appendix for additional information regarding freeze/thaw
durability in service.
4.1.1 Grade SW (Severe Weathering)—Hollow brick intended for use where high resistance to damage caused by cyclic freezing
and thawing is desired.
4.1.2 Grade MW (Moderate Weathering)—Hollow brick intended for use where moderate resistance to cyclic freezing and
thawing damage is permissible.
4.2 Types—Four types of hollow brick are covered:
4.2.1 Type HBS—Hollow brick for general use in masonry.
4.2.2 Type HBX—Hollow brick for general use in masonry where a higher degree of precision and lower permissible variation in
size than permitted for Type HBS is required.
4.2.3 Type HBA—Hollow brick for general use in masonry selected to produce characteristic architectural effects resulting from
nonuniformity in size and texture of the individual units.
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.
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4.2.4 Type HBB—Hollow brick for general use in masonry where a particular color, texture, finish, uniformity, or limits on cracks,
warpage, or other imperfections detracting from the appearance are not a consideration.
4.2.5 When the type is not specified, the requirements for Type HBS shall govern.
4.3 Class—Two classes of hollow brick are covered:
4.3.1 Class H40V—Hollow brick intended for use where void areas or spaces greater than 25 %, but not greater than 40 %, of the
gross cross-sectional area of the unit measured in any plane parallel to the surface containing the cores, cells, or deep frogs are
desired. The void spaces, the web thicknesses, and the shell thicknesses shall comply with the requirements of Section 11 on Coring
and Frogging.
4.3.2 Class H60V—Hollow brick intended for use where larger void areas are desired. The sum of these void areas shall be greater
than 40 %, but not greater than 60 %, of the gross cross-sectional area of the unit measured in any plane parallel to the surface
containing the cores, cells or deep frogs. The void spaces, the web thicknesses, and the shell thicknesses shall comply with the
requirements of Section 11 on Coring and Frogging and to the minimum requirements contained in Table 1 (see Fig. 1).
4.3.3 When the class is not specified, the requirements of Class H40V shall govern.
5. Ordering Information
5.1 Orders for hollow brick under this specification shall include the following information:
5.1.1 Grade (4.1)—Grade SW governs when grade is not specified.
5.1.2 Type (4.2)—Type HBS governs when type is not specified.
5.1.3 Class (4.3)—Specify Class H40V or H60V. or accept Class H40V governs if Class is not specified.
5.1.4 Size (9.1)—Specify size of brick, width by height by length.
5.1.4.1 For Type HBA, specify tolerances on dimensions (9.1), warpage (9.2), or approve a designated sample.
5.1.5 Color, color range, and texture (10.5) by approving a sample.
5.1.5.1 For Type HBB, color, color range and texture are not required.
5.1.6 Finish on more than one face and one end (10.6).
5.1.7 Sampling (12.2)—Place(s) of selection for test specimens.
5.2 Orders for hollow brick under this specification may include the following information:
5.2.1 Strength (7.2)—Specify only if above minimum compressive strength in Table 2.
5.2.2 Special Shapes (10.6)—Specify size, dimensions and finished faces by approved shop drawing or other means.
TABLE 1 Class H60V—Hollow Brick Minimum Thickness
of Face Shells and Webs, in. (mm)
Face Shell Thicknesses
End Shells or
Nominal Width of Units
Cored or Double
End Webs
Solid
Shell
3 3
3 and 4 (76 and 101) ⁄4 (19.05) . ⁄4 (19.05)
6 (152) 1 (25.4) 1 ⁄2 (38) 1 (25.4)
1 1
8 (203) 1 ⁄4 (32) 1 ⁄2 (38) 1 (25.4)
1 5
10 (254) and greater 1 ⁄4 (32) 1 ⁄8 (41) 1 (25.4)
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FIG. 1 Hollow Brick Units
TABLE 2 Physical Requirements
Compressive Strength Water Absorption Saturation
gross area, min, psi by 5-h Coefficient,
Desig-
(MPa) Boiling, max, % max
nation
Average of Average Indi- Average Indi-
Individual
5 brick of 5 brick vidual of 5 brick vidual
Grade SW 3000 (20.7) 2500 (17.2) 17.0 20.0 0.78 0.80
Grade MW 2500 (17.2) 2200 (15.2) 22.0 25.0 0.88 0.90
5.2.3 Frogging (10.5)—Frog permitted in one bearing surface if not specified.
5.2.4 Costs of Tests (Note 11)—Party who will pay and conditions of payment of compliance testing.
NOTE 2—See 6.3 and Section 7 for optional information.
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6. Materials and Manufacture
6.1 The body of all hollow brick shall be of clay, shale, fire clay, or mixtures of these materials, with or without admixtures, burned
to meet the requirements of this specification. Any coloring or other materials added to the clay shall be suitable ceramic materials
and shall be well distributed throughout the body.
6.2 Colors and textures produced by application of inorganic coatings to the finished face(s) of the brick shall be permitted with
the consent of the purchaser, provided that evidence is furnished of the durability of the coatings. Brick that are colored by flashing
or textured by sanding, where the sand does not form a continuous coating, shall not be considered as surface-colored brick for
the purpose of this specification.
NOTE 3—When surface colored brick, other than sanded or flashed, are specified for exterior use, the purchaser should require that data be submitted
showing that after 50 cycles of freezing thawing there is no observable difference in the applied finish when viewed from a distance of 10 ft (3.0 m) under
an illumination of not less than 50 ft-candles (538 lx) by an observer with normal vision.
Service records of the performance of the particular coated brick in exterior locations may be accepted in place of the freezing and thawing test, upon
consent of the purchaser.
6.3 The brick shall be free of defects, deficiencies, and surface treatments, including coatings, that would interfere with the proper
laying of the brick or significantly impair the strength or performance of the construction.
6.4 If any post-firing coatings or surface treatments are applied by the manufacturer, the manufacturer shall report the type and
extent of these coatings or surface treatments in all certificates of compliance with this specification.
7. Physical Properties
7.1 Durability—When grade is not specified, the requirements for Grade SW shall govern.
7.1.1 Physical Property Requirements—The brick shall conform to the physical requirements for the grade specified as prescribed
in Table 2. For the compressive strength requirements in Table 2, test the unit with the compressive force perpendicular to the bed
surface of the unit, with the unit in the stretcher position.
7.1.2 Absorption Alternate—The saturation coefficient requirement does not apply, provided that the 24-h cold water absorption
of each of the five units tested does not exceed 8.0 %.
7.1.3 Freezing and Thawing Alternative—The requirements for 5-h boiling water absorption and saturation coefficient do not
apply, provided a sample of five brick, meeting the strength requirements of Table 2, passes the freezing and thawing test as
described in the Rating Section of the Freezing and Thawing test procedures of Test Methods C67/C67M.
NOTE 4—The 50-cycle freezing and thawing test is used as an alternative only when the brick do not conform to either Table 2 requirements for maximum
water absorption and saturation coefficient, or to the requirements of the Absorption Alternate in 7.1.2.
7.1.3.1 Grade SW: Breakage and Weight Loss Requirement—No individual unit separates or disintegrates resulting in a weight loss
greater than 0.5 % of its original dry weight.
7.1.3.2 Grade SW: Cracking Requirement—No individual unit develops a crack that exceeds, in length, the unit’s least dimension.
7.1.4 Low Weathering Index Alternative:
7.1.4.1 If the brick are intended for use exposed to weather where the weathering index is less than 50 (see Fig. 2), and unless
otherwise specified, the requirements given in Table 2 for 5-h boiling water absorption and for saturation coefficient shall not apply,
but the minimum average compressive strength requirement of 2500 psi (17.2 MPa) shall apply.
NOTE 5—The effect of weathering on brick is related to the weathering index, which for any locality is the product of the average annual number of
freezing cycle days and the average annual winter rainfall in inches, as defined as follows.
Data needed to determine the weathering for any locality may be found or estimated from tables of Local Climatological Data—Annual Summary with Comparative
Data from the National Oceanic and Atmospheric Administration.
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Grade Recommendations for Face Exposures
Weathering Index (Note 5)
Exposure
Less than 50 50 and greater
In vertical surfaces:
In contact with earth SW or MW SW
Not in contact with earth SW or MW SW
In other than vertical surfaces:
In contact with e
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