ASTM C1623-23

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it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: C1623 − 22 C1623 − 23
Standard Specification for
Manufactured Concrete Masonry Lintels
This standard is issued under the fixed designation C1623; 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 concrete masonry lintels (beams) that are solid in cross-section, are reinforced for flexure, and are
made from hydraulic cement, water, and mineral aggregates with or without the inclusion of other materials. These lintels are
suitable for both loadbearing and nonloadbearing applications.
NOTE 1—This specification covers only concrete masonry lintels containing reinforcement. Due to building code imposed limitations on the design of
masonry lintels, all lintels must contain reinforcement. Concrete masonry lintels are not typically manufactured using shear reinforcement (stirrups or
other vertical reinforcement). Therefore, this standard does not address issues related to such. For further guidance, refer to Building Code Requirements
for Masonry Structures, TMS 402. Prestressed concrete lintels are not covered by this standard.
1.2 Lintels are manufactured using a no-slump concrete mix to provide a surface texture similar to that of concrete masonry. This
specification applies to both machine-made and hand-tamped concrete masonry lintels intended for use in concrete masonry
applications.
1.3 Concrete masonry lintels covered by this specification are made from lightweight or normal weight aggregates, or both.
1.4 This specification does not address the design or analysis of lintel capacity. Structural evaluations must be performed
separately. The strength of a lintel is a function of factors including, but not limited to, the characteristics of the materials used
in manufacturing (concrete materials and reinforcement), the amount and location of reinforcement, and the manufacturing and
curing procedures. For design and analysis methods, refer to Building Code Requirements for Masonry Structures, TMS 402.
1.5 This specification does not cover U-shaped lintels or those of other cross-sections that are not 100 % solid.
1.6 This specification does not cover lintels of grouted concrete masonry lintels, or precast or cast-in-place lintels of slump
concrete.
1.7 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.
1.8 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.
This specification is under the jurisdiction of ASTM Committee C15 on Manufactured Masonry Units and is the direct responsibility of Subcommittee C15.03 on
Concrete Masonry Units and Related Units.
Current edition approved Dec. 15, 2022Dec. 1, 2023. Published January 2023December 2023. Originally approved in 2005. Last previous edition approved in 20172022
as C1623 – 17a.C1623 – 22. DOI: 10.1520/C1623-23.
*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
C1623 − 23
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:
A615/A615M Specification for Deformed and Plain Carbon-Steel Bars for Concrete Reinforcement
A706/A706M Specification for Deformed and Plain Low-Alloy Steel Bars for Concrete Reinforcement
A996/A996M Specification for Rail-Steel and Axle-Steel Deformed Bars for Concrete Reinforcement
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
C1262/C1262M Test Method for Evaluating the Freeze-Thaw Durability of Dry-Cast Segmental Retaining Wall Units and
Related Concrete Units
2.2 Other Standards:
TMS 402 Building Code Requirements for Masonry Structures
TMS 602 Specification for Masonry Structures
3. Terminology
3.1 Terminology defined in Terminology C1232 shall apply for this specification.
4. Material
4.1 Cementitious Materials—Materials Cementitious materials shall conform to the following applicable specifications:
4.1.1 Portland Cement—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 be not 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 on 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:
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.
Available from The Masonry Society, 105 South Sunset Street, Suite Q, Longmont, CO 80501–6172, https://www.masonrysociety.org.
C1623 − 23
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 manufactured concrete masonry lintel
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 Steel Reinforcement—Steel reinforcement shall consist of deformed bars conforming to Specifications A615/A615M,
A706/A706M, or A996/A996M.
4.5 Other Constituents—Air-entraining agents, integral water repellents, and other constituents shall be previously established as
suitable for use in concrete masonry lintels and shall conform to applicable ASTM standards or shall be shown by test or
experience not to be detrimental to the durability of the concrete masonry lintels or any material customarily used in masonry
construction.
5. Physical Requirements
5.1 At the time of delivery to the purchaser, the concrete within the lintel shall conform to the requirements prescribed in Table
1.
5.1.1 When higher compressive strengths than those listed in Table 1 are specified, the tested average net area compressive
strength of three specimens shall equal or exceed the specified compressive strength, and the tested individual specimen net area
compressive strength of all three units shall exceed 90 % of the specified compressive strength.
NOTE 3—When particular features are desired such as surface textures for appearance or bond, finish, color, or particular properties such as specific
reinforcing schedules, flexural strength, weight per unit length, higher compressive strength, or fire resistance, these features are specified separately by
the purchaser. Consult suppliers as to the availability of lintels having the desired features.
5.2 All lintels shall be sound and free of cracks or other defects that interfere with proper placement unless defects are considered
to be not detrimental to structural capacity of the lintel before or after defects are repaired using practices satisfactory to the
engineer.
NOTE 4—The purchaser is the public body or authority, association, corporation, partnership, or individual entering into a contract or agreement to
purchase or install, or both, concrete masonry lintels. The time of delivery to the purchaser is FOB plant when the purchaser or the purchaser’s agent
transports the concrete masonry lintels, or at the time unloaded at the worksite if the manufacturer or the manufacturer’s agent transports the concrete
masonry lintels.
NOTE 5—When these lintels are used in above-grade applications as part of a vertical, free-draining assemblage, the physical requirements in this
specification have been shown to result in durable products. In applications where the lintels are frequently exposed to deicing chemicals or saturated
conditions in conjunction with freezing and thawing temperatures, testing should be considered to evaluate freezing and thawing resistance using ASTM
C1262/C1262M.
A
TABLE 1 Strength, Absorption, and Density Classification Requirements
Density Classification Oven-Dry Density Maximum Water Minimum Net Area
3 3 3 3
of Concrete, lb/ft (kg/m ) Absorption, lb/ft (kg/m ) Compressive Strength,
psi (MPa)
Average of Average of Individual Average of Individual
B B B B B
3 Specimens 3 Specimens Specimen 3 Specimens Specimen
Lightweight Less than105 (1680) 18 (288) 20 (320) 2500 (17.2) 2250 (15.5)
Medium Weight 105 to less than 125 (1680–2000) 15 (240) 17 (272) 2500 (17.2) 2250 (15.5)
...