ASTM A1094/A1094M-20

Standard Specification for Continuous Hot-Dip Galvanized Steel Bars for Concrete Reinforcement

ABSTRACT
This specification covers requirements for steel reinforcing bars, with protective zinc or zinc-alloy coatings applied by the continuous hot-dip process. Continuous hot-dip galvanizing refers to the process of uninterrupted passage of long lengths of steel products through a molten bath of zinc or zinc-alloy. To control alloy formation and promote adhesion of the zinc or zinc-alloy coating with the steel base metal, the molten coating metal composition typically contains a percentage of aluminum ranging from 0.05 to 0.25. This aluminum is purposely supplied to the molten coating bath, either as a specified ingredient in the zinc spelter or by the addition of a master alloy containing aluminum.
This specification prescribes ordering information (including specification for reinforcing bars to be coated, quantity of bars, and size and grade of bars) as well as requirements for steel reinforcing bars and coating bath metal; minimum average coating thickness grade and equivalent weight [mass]; finish and adherence of coating; inspection and certification; and permissible amount of damaged coating and repair of damaged coating.
SCOPE
1.1 This specification covers steel reinforcing bars, with protective zinc or zinc-alloy coatings applied by the continuous hot-dip process.
Note 1: The galvanizer is identified throughout this specification as the manufacturer.  
1.2 Guidelines for construction practices at the job-site are presented in Appendix X1.  
1.3 Guidelines for use of continuous hot-dip galvanized reinforcing bars with non-galvanized steel forms are presented in Appendix X2.  
1.4 The text of this specification references notes and footnotes which provide explanatory material. These notes and footnotes shall not be considered requirements of the specification.  
1.5 This specification is applicable for orders in either inch-pound units (as Specification A1094) or SI units (as Specification A1094M).  
1.6 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with this specification.  
1.7 This specification 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 specification to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.8 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: 31-Aug-2020
• ICS: 77.140.15 - Steels for reinforcement of concrete
• Technical Committee: A01 - Steel, Stainless Steel and Related Alloys
• Drafting Committee: A01.05 - Steel Reinforcement

Relations

• Refers: ASTM A1035/A1035M-23a - Standard Specification for Deformed and Plain, Low-Carbon, Chromium, Steel Bars for Concrete Reinforcement
• Effective Date: 01-Nov-2023
• Refers: ASTM A1035/A1035M-19 - Standard Specification for Deformed and Plain, Low-Carbon, Chromium, Steel Bars for Concrete Reinforcement
• Effective Date: 01-Sep-2019
• Refers: ASTM E376-19 - Standard Practice for Measuring Coating Thickness by Magnetic-Field or Eddy Current (Electromagnetic) Testing Methods
• Effective Date: 01-May-2019
• Refers: ASTM E376-17 - Standard Practice for Measuring Coating Thickness by Magnetic-Field or Eddy Current (Electromagnetic) Testing Methods
• Effective Date: 01-Nov-2017
• Refers: ASTM A1035/A1035M-16b - Standard Specification for Deformed and Plain, Low-Carbon, Chromium, Steel Bars for Concrete Reinforcement
• Effective Date: 15-Oct-2016
• Refers: ASTM B852-16 - Standard Specification for Continuous Galvanizing Grade (CGG) Zinc Alloys for Hot-Dip Galvanizing of Sheet Steel
• Effective Date: 01-May-2016
• Refers: ASTM A1035/A1035M-16a - Standard Specification for Deformed and Plain, Low-Carbon, Chromium, Steel Bars for Concrete Reinforcement
• Effective Date: 01-Mar-2016
• Refers: ASTM A1035/A1035M-16 - Standard Specification for Deformed and Plain, Low-Carbon, Chromium, Steel Bars for Concrete Reinforcement
• Effective Date: 15-Jan-2016
• Refers: ASTM A996/A996M-15 - Standard Specification for Rail-Steel and Axle-Steel Deformed Bars for Concrete Reinforcement
• Effective Date: 01-Jul-2015
• Refers: ASTM A1035/A1035M-15 - Standard Specification for Deformed and Plain, Low-Carbon, Chromium, Steel Bars for Concrete Reinforcement
• Effective Date: 01-Jul-2015
• Refers: ASTM A615/A615M-15 - Standard Specification for Deformed and Plain Carbon-Steel Bars for Concrete Reinforcement
• Effective Date: 01-Apr-2015
• Refers: ASTM A996/A996M-14a - Standard Specification for Rail-Steel and Axle-Steel Deformed Bars for Concrete Reinforcement
• Effective Date: 01-Oct-2014
• Refers: ASTM B852-14 - Standard Specification for Continuous Galvanizing Grade (CGG) Zinc Alloys for Hot-Dip Galvanizing of Sheet Steel
• Effective Date: 01-Oct-2014
• Refers: ASTM A615/A615M-14 - Standard Specification for Deformed and Plain Carbon-Steel Bars for Concrete Reinforcement
• Effective Date: 01-Apr-2014
• Refers: ASTM A1035/A1035M-14 - Standard Specification for Deformed and Plain, Low-Carbon, Chromium, Steel Bars for Concrete Reinforcement
• Effective Date: 01-Mar-2014

Overview

ASTM A1094/A1094M-20 is a standard developed by ASTM International that sets forth the requirements for continuous hot-dip galvanized steel bars used in concrete reinforcement. This specification focuses on steel reinforcing bars with protective zinc or zinc-alloy coatings applied through a continuous hot-dip process. The standard addresses the processes for coating, inspection, and acceptance of galvanized steel reinforcing bars, as well as guidelines for handling, storage, and usage on construction sites. It is dual-unit, covering both inch-pound and SI units for international applicability.

Using galvanized steel bars significantly enhances corrosion resistance, making them ideal for reinforcing concrete in aggressive environments and infrastructure with long service life requirements.

Key Topics

• Continuous Hot-Dip Galvanizing Process: Describes the uninterrupted process of passing steel bars through a molten bath of zinc or zinc-alloy, typically containing 0.05–0.25% aluminum to ensure proper adhesion and alloy formation.
• Material Requirements: Specifies the types of steel bars permissible for coating, which must comply with standards such as ASTM A615, A706, A996, and A1035.
• Coating and Finish: Details minimum coating thickness, finish, appearance, and requirements for adherence. It prescribes procedures for thickness measurement and outlines permissible methods for coating repair if accidental damage occurs.
• Inspection and Certification: Outlines inspection agreements between purchaser and manufacturer, stipulates certification and reporting at shipment, and the possibility of using electronic data interchange for documentation.
• Jobsite and Construction Guidelines: Provides non-mandatory appendices on best practices for handling, storage, off-loading, separation of coated and uncoated bars, and repair of field damage using zinc-rich materials.
• Use with Non-Galvanized Forms: Advises on electrical isolation to prevent unwanted visual effects ("shadowing") on the finished concrete surface when galvanized bars are used with steel or stainless steel forms.

Applications

The ASTM A1094/A1094M-20 specification is widely implemented in:

• Bridge and Infrastructure Projects: Galvanized rebar is used in bridges, highways, and marine structures to extend the lifespan of concrete exposed to chlorides, deicing salts, and humidity.
• Building Construction: Used in foundation elements, slabs, and precast concrete components where added durability against corrosion is required.
• Water and Wastewater Facilities: Ideal for reinforcing tanks, treatment plants, and pipelines where constant water exposure risks steel corrosion.
• Parking Structures and Foundations: Provides extra protection for structural concrete exposed to temperature fluctuations and water intrusion.

Related Standards

ASTM A1094/A1094M-20 references several other ASTM documents crucial for compliance and proper specification:

• ASTM A615/A615M: Deformed and Plain Carbon-Steel Bars for Concrete Reinforcement
• ASTM A706/A706M: Deformed and Plain Low-Alloy Steel Bars for Concrete Reinforcement
• ASTM A996/A996M: Rail-Steel and Axle-Steel Deformed Bars for Concrete Reinforcement
• ASTM A1035/A1035M: Low-Carbon, Chromium, Steel Bars for Concrete Reinforcement
• ASTM B6: Specification for Zinc
• ASTM B487: Measurement of Metal and Oxide Coating Thickness by Microscopy
• ASTM A780/A780M: Repair of Damaged and Uncoated Areas of Hot-Dip Galvanized Coatings
• ASTM E376: Measuring Coating Thickness by Magnetic-Field or Eddy Current Methods

Practical Value

Specifying continuous hot-dip galvanized steel bars according to ASTM A1094/A1094M-20 ensures enhanced corrosion resistance and structural durability, crucial for demanding environments. The standard provides clear, actionable requirements for manufacturers, specifiers, and contractors, supporting the creation of long-lasting reinforced concrete structures with minimized maintenance over time.

Keywords: ASTM A1094, galvanized steel bars, hot-dip galvanized rebar, concrete reinforcement, corrosion resistance, zinc coating, construction standards, ASTM International, reinforced concrete durability

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:A1094/A1094M −20
Standard Specification for
Continuous Hot-Dip Galvanized Steel Bars for Concrete
Reinforcement
This standard is issued under the fixed designation A1094/A1094M; 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* Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
1.1 This specification covers steel reinforcing bars, with
Barriers to Trade (TBT) Committee.
protectivezincorzinc-alloycoatingsappliedbythecontinuous
hot-dip process.
2. Referenced Documents
NOTE 1—The galvanizer is identified throughout this specification as
2.1 ASTM Standards:
the manufacturer.
A90/A90M Test Method for Weight [Mass] of Coating on
1.2 Guidelines for construction practices at the job-site are
Iron and Steel Articles with Zinc or Zinc-Alloy Coatings
presented in Appendix X1.
A615/A615M SpecificationforDeformedandPlainCarbon-
Steel Bars for Concrete Reinforcement
1.3 Guidelines for use of continuous hot-dip galvanized
A706/A706M Specification for Deformed and Plain Low-
reinforcing bars with non-galvanized steel forms are presented
Alloy Steel Bars for Concrete Reinforcement
in Appendix X2.
A780/A780M PracticeforRepairofDamagedandUncoated
1.4 The text of this specification references notes and
Areas of Hot-Dip Galvanized Coatings
footnotes which provide explanatory material. These notes and
A996/A996M Specification for Rail-Steel and Axle-Steel
footnotes shall not be considered requirements of the specifi-
Deformed Bars for Concrete Reinforcement
cation.
A1035/A1035M Specification for Deformed and Plain,
1.5 This specification is applicable for orders in either
Low-Carbon, Chromium, Steel Bars for Concrete Rein-
inch-pound units (as Specification A1094) or SI units (as
forcement
Specification A1094M).
B6 Specification for Zinc
B487 Test Method for Measurement of Metal and Oxide
1.6 The values stated in either inch-pound units or SI units
Coating Thickness by Microscopical Examination of
are to be regarded separately as standard. Within the text, the
Cross Section
SI units are shown in brackets. The values stated in each
B852 Specification for Continuous Galvanizing Grade
system may not be exact equivalents; therefore, each system
(CGG) Zinc Alloys for Hot-Dip Galvanizing of Sheet
shall be used independently of the other. Combining values
Steel
from the two systems may result in non-conformance with this
E376 Practice for Measuring Coating Thickness by
specification.
Magnetic-Field or Eddy Current (Electromagnetic) Test-
1.7 This specification does not purport to address all of the
ing Methods
safety concerns, if any, associated with its use. It is the
responsibility of the user of this specification to establish
3. Terminology
appropriate safety, health, and environmental practices and
3.1 Definitions of Terms Specific to This Specification:
determine the applicability of regulatory limitations prior to
3.1.1 continuous hot-dip galvanizing, n—the process of
use.
uninterrupted passage of long lengths of steel products through
1.8 This international standard was developed in accor-
a molten bath of zinc or zinc-alloy.
dance with internationally recognized principles on standard-
3.1.1.1 Discussion—Tocontrolalloyformationandpromote
ization established in the Decision on Principles for the
adhesion of the zinc or zinc-alloy coating with the steel base
metal, the molten coating metal composition normally contains
This specification is under the jurisdiction ofASTM Committee A01 on Steel,
Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee
A01.05 on Steel Reinforcement. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Sept. 1, 2020. Published September 2020. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 2015. Last previous edition approved in 2018 as A1094/A1094M – 18. Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/A1094_A1094M-20. 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
A1094/A1094M−20
a percentage of aluminum usually in the range from 0.05 to 6.3 Thickness of Coating:
0.25. This aluminum is purposely supplied to the molten 6.3.1 The average thickness of zinc or zinc-alloy coating for
coating bath, either as a specified ingredient in the zinc spelter all specimens tested shall not be less than specified in Table 1.
or by the addition of a master alloy containing aluminum.
6.4 Coating Thickness Tests:
3.1.2 lot, n—all bars of one size furnished to the same steel
6.4.1 Coating thickness tests shall be performed in accor-
reinforcing bar specification that have been coated within a dance with one of the following test methods:
single production shift.
6.4.1.1 Magnetic Thickness Gauge Measurements—The
thickness of the coating shall be determined by magnetic
4. Ordering Information
thickness gauge measurements in accordance with Practice
4.1 Orders for continuous hot-dip galvanized steel bars for E376,or
6.4.1.2 Microscopy—The thickness of the coating shall be
concrete reinforcement under this specification shall include
the following information: determined by cross-sectional and optical measurement in
accordance with Test Method B487.Across-section sample of
4.1.1 Specification for reinforcing bars, deformed or plain,
to be coated (ASTM designation and year of issue) (5.1), the coated steel shall be polished and examined with an optical
4.1.2 Quantity of bars, microscope to determine the coating thickness. Measurements
4.1.3 Size and grade of bars, and of thickness shall not be taken on points located on ribs or
4.1.4 ASTM designation A1094 [A1094M] and year of deformations, or
issue. 6.4.1.3 Stripping Method—The thickness of the coating
shall be determined by stripping the coating from a reinforcing
4.2 Thepurchasershallhavetheoptiontospecifyadditional
bar in accordance with Test Method A90/A90M. This test
requirements, including but not limited to, the following:
method shall not be used for deformed steel reinforcing bars.
4.2.1 If chromate treatment is waived (6.5),
4.2.2 Requirements for inspection (8.1), NOTE 3—Due to variations in the surface areas of deformed bars as a
function of deformation pattern and bar size, this method to measure
4.2.3 Manufacturer certification and report of test results
coating thickness is not appropriate for deformed bars. This is a destruc-
(10.1), and
tive test for small samples of plain bars with a minimum of 3 in. [2000
4.2.4 Other special requirements, if any. 2
mm ] of surface area,
6.4.2 The referee method to be used shall be Test Method
5. Materials
B487.
5.1 The steel reinforcing bars shall conform to one of the
6.4.3 Number of Tests—For determination of the coating
following specifications: A615, A706, A996, or A1035
thickness using the magnetic method, three random samples
[A615M, A706M, A996M, or A1035M].
shall be tested from each lot. For each magnetic thickness
5.2 Coating Bath Metal—The bath metal used to produce
gauge measurement sample, five or more measurements shall
continuoushot-dipgalvanizedsteelbarsforconcretereinforce-
be made at various points throughout the sample so as to
mentshallmeettherequirementsofSpecificationsB6orB852.
represent the entire surface of the sample. A total of at least
fifteen measurements shall be averaged to obtain the coating
6. Zinc Coating Process
thickness. For the microscopy method, five samples shall be
6.1 The reinforcing bars shall be coated by passing indi-
tested per lot. Each sample shall be measured on four sides and
vidual bars through a zinc or zinc-alloy flooded trough or tube
the total of twenty measurements shall be averaged to obtain
located above a zinc or zinc-alloy bath, then immediately
the coating thickness. For the stripping method, three samples
throughanairorsteamwipingdevicetoremoveexcesscoating
per lot shall be tested.
from the bars.
6.4.4 Retests—If the average zinc coating thickness fails to
meet the requirements of Table 1, six additional random
NOTE 2—During the wiping process, care should be taken to maintain
samples from the lot shall be tested. If the average zinc coating
a uniformly thick coating around the perimeter of the bar.
thickness of the six samples conforms to the requirements of
6.2 It shall be the responsibility of the manufacturer to
Table 1, the lot shall be accepted.
maintain identity of the reinforcing bars throughout the coating
6.5 Chromating—Thezinccoatingshallbechromatetreated
process and to the point of shipment.
unless waived by the purchaser.
NOTE 4—The purpose of chromate treatment is to preclude a reaction
between the bars and fresh portland cement paste.
6.5.1 If the chromate treatment is performed immediately
after zinc or zinc-alloy coating, it shall be accomplished by
TABLE 1 Minimum Average Coating Thickness Grade and
A
Equivalent Weight [Mass]
quenching the steel reinforcing bars in a solution containing at
Coating
2 2 2 least 0.2 weight [mass] % of pure sodium dichromate in water
µm mils oz/ft g/m mg/cm
Grade 3
(such as 3 oz/10 gal [2 kg/m ] of quench water) or by quench
50 50 2.0 1.2 360 36
chromating in a minimum of 0.2 % chromic acid solution. The
A
The value in micrometres (µm) is based on the Coating Grade.The other values
solution shall be at least 90°F [32°C]. The zinc or zinc-alloy
arebasedonconventionsusingthefollowingformulae:mils=µm×0.03937;oz/ft
2 2 coated reinforcing bars shall be immersed in the solution for at
= µm × 0.0232; g/m = µm × 7.14; and mg/cm = µm × 0.714.
least 20 s.
A1094/A1094M−20
NOTE 5—Propr
...

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: A1094/A1094M − 18 A1094/A1094M − 20
Standard Specification for
Continuous Hot-Dip Galvanized Steel Bars for Concrete
Reinforcement
This standard is issued under the fixed designation A1094/A1094M; 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 steel reinforcing bars, with protective zinc or zinc-alloy coatings applied by the continuous hot-dip
process.
NOTE 1—The galvanizer is identified throughout this specification as the manufacturer.
1.2 Guidelines for construction practices at the job-site are presented in Appendix X1.
1.3 Guidelines for use of continuous hot-dip galvanized reinforcing bars with non-galvanized steel forms are presented in
Appendix X2.
1.4 The text of this specification references notes and footnotes which provide explanatory material. These notes and footnotes
shall not be considered requirements of the specification.
1.5 This specification is applicable for orders in either inch-pound units (as Specification A1094) or SI units (as Specification
A1094M).
1.6 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units
are shown in brackets. The values stated in each system may not be exact equivalents; therefore, each system shall be used
independently of the other. Combining values from the two systems may result in non-conformance with this specification.
1.7 This specification 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 specification to establish appropriate safety, health, and environmental practices and determine the applicability
of regulatory limitations prior to use.
1.8 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.
This specification is under the jurisdiction of ASTM Committee A01 on Steel, Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee A01.05
on Steel Reinforcement.
Current edition approved Nov. 1, 2018Sept. 1, 2020. Published November 2018September 2020. Originally approved in 2015. Last previous edition approved in 20162018
as A1094/A1094M – 16.18. DOI: 10.1520/A1094_A1094M-18.10.1520/A1094_A1094M-20.
*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
A1094/A1094M − 20
2. Referenced Documents
2.1 ASTM Standards:
A90/A90M Test Method for Weight [Mass] of Coating on Iron and Steel Articles with Zinc or Zinc-Alloy Coatings
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
A780/A780M Practice for Repair of Damaged and Uncoated Areas of Hot-Dip Galvanized Coatings
A996/A996M Specification for Rail-Steel and Axle-Steel Deformed Bars for Concrete Reinforcement
A1035/A1035M Specification for Deformed and Plain, Low-Carbon, Chromium, Steel Bars for Concrete Reinforcement
B6 Specification for Zinc
B487 Test Method for Measurement of Metal and Oxide Coating Thickness by Microscopical Examination of Cross Section
B852 Specification for Continuous Galvanizing Grade (CGG) Zinc Alloys for Hot-Dip Galvanizing of Sheet Steel
E376 Practice for Measuring Coating Thickness by Magnetic-Field or Eddy Current (Electromagnetic) Testing Methods
3. Terminology
3.1 Definitions of Terms Specific to This Specification:
3.1.1 continuous hot-dip galvanizing, n—the process of uninterrupted passage of long lengths of steel products through a molten
bath of zinc or zinc-alloy.
3.1.1.1 Discussion—
To control alloy formation and promote adhesion of the zinc or zinc-alloy coating with the steel base metal, the molten coating
metal composition normally contains a percentage of aluminum usually in the range from 0.05 to 0.25. This aluminum is purposely
supplied to the molten coating bath, either as a specified ingredient in the zinc spelter or by the addition of a master alloy containing
aluminum.
3.1.2 lot, n—all bars of one size furnished to the same steel reinforcing bar specification that have been coated within a single
production shift.
4. Ordering Information
4.1 Orders for continuous hot-dip galvanized steel bars for concrete reinforcement under this specification shall include the
following information:
4.1.1 Specification for reinforcing bars, deformed or plain, to be coated (ASTM designation and year of issue) (5.1),
4.1.2 Quantity of bars,
4.1.3 Size and grade of bars, and
4.1.4 ASTM designation A1094 [A1094M] and year of issue.
4.2 The purchaser shall have the option to specify additional requirements, including but not limited to, the following:
4.2.1 If chromate treatment is waived (6.5),
4.2.2 Requirements for inspection (8.1),
4.2.3 Manufacturer certification and report of test results (10.1), and
4.2.4 Other special requirements, if any.
5. Materials
5.1 The steel reinforcing bars shall conform to one of the following specifications: A615, A706, A996or, A996or A1035 [A615M,
A706M, A996Mor , or A996MA1035M].
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.
A1094/A1094M − 20
5.2 Coating Bath Metal—The bath metal used to produce continuous hot-dip galvanized steel bars for concrete reinforcement shall
meet the requirements of Specifications B6 or B852.
6. Zinc Coating Process
6.1 The reinforcing bars shall be coated by passing individual bars through a zinc or zinc-alloy flooded trough or tube located
above a zinc or zinc-alloy bath, then immediately through an air or steam wiping device to remove excess coating from the bars.
NOTE 2—During the wiping process, care should be taken to maintain a uniformly thick coating around the perimeter of the bar.
6.2 It shall be the responsibility of the manufacturer to maintain identity of the reinforcing bars throughout the coating process
and to the point of shipment.
6.3 Thickness of Coating:
6.3.1 The average thickness of zinc or zinc-alloy coating for all specimens tested shall not be less than specified in Table 1.
TABLE 1 Minimum Average Coating Thickness Grade and
A
Equivalent Weight [Mass]
Coating
2 2 2
μm mils oz/ft g/m mg/cm
Grade
50 50 2.0 1.2 360 36
A
The value in micrometres (μm) is based on the Coating Grade. The other values
are based on conventions using the following formulae: mils = μm × 0.03937; oz/ft
2 2
= μm × 0.0232; g/m = μm × 7.14; and mg/cm = μm × 0.714.
A1094/A1094M − 20
6.4 Coating Thickness Tests:
6.4.1 Coating thickness tests shall be performed in accordance with one of the following test methods:
6.4.1.1 Magnetic Thickness Gauge Measurements—The thickness of the coating shall be determined by magnetic thickness gauge
measurements in accordance with Practice E376, or
6.4.1.2 Microscopy—The thickness of the coating shall be determined by cross-sectional and optical measurement in accordance
with Test Method B487. A cross-section sample of the coated steel shall be polished and examined with an optical microscope to
determine the coating thickness. Measurements of thickness shall not be taken on points located on ribs or deformations, or
6.4.1.3 Stripping Method—The thickness of the coating shall be determined by stripping the coating from a reinforcing bar in
accordance with Test Method A90/A90M. This test method shall not be used for deformed steel reinforcing bars.
NOTE 3—Due to variations in the surface areas of deformed bars as a function of deformation pattern and bar size, this method to measure coating
2 2
thickness is not appropriate for deformed bars. This is a destructive test for small samples of plain bars with a minimum of 3 in. [200[2000 mm ] of
surface area,
6.4.2 The referee method to be used shall be Test Method B487.
6.4.3 Number of Tests—For determination of the coating thickness using the magnetic method, three random samples shall be
tested from each lot. For each magnetic thickness gauge measurement sample, five or more measurements shall be made at various
points throughout the sample so as to represent the entire surface of the sample. A total of at least fifteen measurements shall be
averaged to obtain the coating thickness. For the microscopy method, five samples shall be tested per lot. Each sample shall be
measured on four sides and the total of twenty measurements shall be averaged to obtain the coating thickness. For the stripping
method, three samples per lot shall be tested.
6.4.4 Retests—If the average zinc coating thickness fails to meet the requirements of Table 1, six additional random samples from
the lot shall be tested. If the average zinc coating thickness of the six samples conforms to the requirements of Table 1, the lot shall
be accepted.
6.5 Chromating—The zinc coating shall be chromate treated unless waived by the purchaser.
NOTE 4—The purpose of chromate treatment is to preclude a reaction between the bars and fresh portland cement paste.
6.5.1 If the chromate treatment is performed immediately after zinc or zinc-alloy coating, it shall be accomplished by quenching
the steel reinforcing bars in a solution containing at least 0.2 weight [mass] % of pure sodium dichromate in water (such as 3 oz/10
gal [2 kg/m ] of quench water) or by quench chromating in a minimum of 0.2 % chromic acid solution. The solution shall be at
least 90°F [32°C]. The zinc or zinc-alloy coated reinforcing bars sha
...