ASTM A1061/A1061M-20ae1

Standard Test Methods for Testing Multi-Wire Steel Prestressing Strand

SIGNIFICANCE AND USE
4.1 The breaking strength and elongation of the strand are determined by one or more tensile tests in which fracture of the specimen ideally occurs in the free span.  
4.2 Mechanical properties of the strand will be negatively affected if proper care is not taken to prevent damage such as severe bending, abrasion, or nicking of the strand during sampling.  
4.3 Premature failure of the test specimens may result if there is appreciable notching, cutting, or bending of the specimen by the gripping devices of the testing machine.  
4.4 Errors in testing will result if the wires constituting the strand are not loaded uniformly.  
4.5 The mechanical properties of the strand will be materially affected by excessive heating during test specimen collection or preparation.
SCOPE
1.1 These test methods describe procedures for testing the mechanical properties of multi-wire steel prestressing strand.  
1.2 These test methods are intended for use in evaluating specific strand properties prescribed in specifications for multi-wire steel prestressing strand, but they do not quantify acceptance criteria specified in the applicable specification for the strand being tested.  
1.3 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 are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 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-Jun-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 A370-24 - Standard Test Methods and Definitions for Mechanical Testing of Steel Products
• Effective Date: 01-Mar-2024
• Refers: ASTM A370-19 - Standard Test Methods and Definitions for Mechanical Testing of Steel Products
• Effective Date: 01-Jul-2019
• Refers: ASTM A370-17a - Standard Test Methods and Definitions for Mechanical Testing of Steel Products
• Effective Date: 15-Nov-2017
• Refers: ASTM A370-17 - Standard Test Methods and Definitions for Mechanical Testing of Steel Products
• Effective Date: 01-Jan-2017
• Refers: ASTM A370-15 - Standard Test Methods and Definitions for Mechanical Testing of Steel Products
• Effective Date: 01-Nov-2015
• Refers: ASTM E4-14 - Standard Practices for Force Verification of Testing Machines
• Effective Date: 01-Jun-2014
• Refers: ASTM A370-14 - Standard Test Methods and Definitions for Mechanical Testing of Steel Products
• Effective Date: 15-May-2014
• Refers: ASTM E177-14 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2014
• Refers: ASTM A370-13 - Standard Test Methods and Definitions for Mechanical Testing of Steel Products
• Effective Date: 15-Nov-2013
• Refers: ASTM E691-13 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-May-2013
• Refers: ASTM E177-13 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2013
• Refers: ASTM A370-12a - Standard Test Methods and Definitions for Mechanical Testing of Steel Products
• Effective Date: 15-Oct-2012
• Refers: ASTM A370-12 - Standard Test Methods and Definitions for Mechanical Testing of Steel Products
• Effective Date: 15-Mar-2012
• Refers: ASTM A370-11a - Standard Test Methods and Definitions for Mechanical Testing of Steel Products
• Effective Date: 15-Nov-2011
• Refers: ASTM E691-11 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2011

Overview

ASTM A1061/A1061M-20ae1 is the globally recognized standard developed by ASTM International for the testing of multi-wire steel prestressing strand. This document establishes the procedures for reliably determining the mechanical properties-namely, breaking strength and elongation-of multi-wire steel strands using tensile tests, adhering to best practices for accuracy and consistency. The standard supports compliance with both inch-pound and SI units, ensuring its relevance for international stakeholders in the construction, materials, and civil engineering sectors.

Compliance with ASTM A1061/A1061M-20ae1 ensures that multi-wire steel prestressing strands meet quality requirements necessary for structural performance, providing confidence to manufacturers, project owners, quality control laboratories, and regulatory agencies alike.

Key Topics

• Mechanical Properties Testing:

  • Outlines procedures for tensile tests to determine breaking strength and elongation. Ideal fracture occurs in the free span-away from the gripping points.

• Specimen Preparation:

  • Emphasizes care to prevent damage such as bending, abrasion, or excessive heating during sampling, handling, or test preparation, as these can adversely affect results.

• Testing Methodology:

  • Describes sample gripping devices and techniques to avoid premature failure due to equipment-induced notching or uneven loading.
  • Specifies use of extensometers or equivalent precision measurement tools for accurate yield strength and elongation readings.

• Result Validity and Error Prevention:

  • Details how premature failures or wire slippage during testing can invalidate results.
  • Highlights importance of uniform loading of wires to avoid errors.

• Reporting Requirements:

  • Mandates reporting of strand dimensions, grade, manufacturer, date, test number, and measured mechanical properties.

• International Applicability:

  • Stresses separate adherence to inch-pound and SI units to cater to diverse regulatory environments.

Applications

The ASTM A1061/A1061M-20ae1 standard is vital for:

• Strand Manufacturers: Ensuring production quality of multi-wire steel prestressing strand used in concrete reinforcement for bridges, buildings, and other critical infrastructure.

• Quality Assurance Laboratories: Conducting reliable, reproducible, and precise strength and elongation testing on steel prestressing strand samples.

• Civil Engineering Projects: Verifying that the steel strand used in pre-tensioned or post-tensioned concrete structures meets design specifications relating to tensile performance.

• Construction Contractors: Supporting compliance with project specifications and regulatory requirements for structural reliability.

• Regulatory Authorities and Third-Party Auditors: Providing an objective, standardized method for assessing product conformity in procurement and inspection processes.

Related Standards

For broader context or complementary testing, consider the following ASTM standards:

• ASTM A370: Test Methods and Definitions for Mechanical Testing of Steel Products
• ASTM E4: Practices for Force Verification of Testing Machines
• ASTM E83: Practice for Verification and Classification of Extensometer Systems
• ASTM E328: Test Methods for Stress Relaxation for Materials and Structures
• ASTM E177: Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• ASTM E691: Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

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Keywords: multi-wire steel prestressing strand, ASTM A1061/A1061M, mechanical properties testing, tensile strength, elongation, strand gripping devices, steel reinforcement, quality control, construction standards, civil engineering materials.

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.
´1
Designation: A1061/A1061M −20a
Standard Test Methods for
Testing Multi-Wire Steel Prestressing Strand
This standard is issued under the fixed designation A1061/A1061M; 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.
ε NOTE—The research report footnote in Section 11 was editorially updated in August 2020.
1. Scope* E4 Practices for Force Verification of Testing Machines
E83 Practice for Verification and Classification of Exten-
1.1 These test methods describe procedures for testing the
someter Systems
mechanical properties of multi-wire steel prestressing strand.
E177 Practice for Use of the Terms Precision and Bias in
1.2 These test methods are intended for use in evaluating
ASTM Test Methods
specific strand properties prescribed in specifications for multi-
E328 Test Methods for Stress Relaxation for Materials and
wire steel prestressing strand, but they do not quantify accep-
Structures
tance criteria specified in the applicable specification for the
E691 Practice for Conducting an Interlaboratory Study to
strand being tested.
Determine the Precision of a Test Method
1.3 The values stated in either inch-pound units or SI units
3. Terminology
are to be regarded separately as standard. Within the text, the
SI units are shown in brackets. The values stated in each
3.1 Definitions of Terms Specific to This Standard:
system are not necessarily exact equivalents; therefore, to
3.1.1 breaking strength, n—maximum force at or after
ensure conformance with the standard, each system shall be
which one or more wires fracture.
used independently of the other, and values from the two
3.1.2 free span, n—the distance between the gripping jaws
systems shall not be combined.
occupiedbythelengthofstrandtobetestedinwhichthestrand
1.4 This standard does not purport to address all of the
is not contacted or detrimentally influenced by the gripping
safety concerns, if any, associated with its use. It is the
system.
responsibility of the user of this standard to establish appro-
3.1.3 lay length, n—the axial distance required to make one
priate safety, health, and environmental practices and deter-
complete revolution of any wire of a strand.
mine the applicability of regulatory limitations prior to use.
3.1.4 strand, n—a group of two, three or seven steel wires
1.5 This international standard was developed in accor-
woundtogetherinahelicalformwithuniformlaylengthofnot
dance with internationally recognized principles on standard-
less than 12 and not more than 16 times the nominal diameter
ization established in the Decision on Principles for the
of the strand.
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical 3.1.5 yield strength, n—measured force at 1.0 % extension
Barriers to Trade (TBT) Committee. under load (EUL).
4. Significance and Use
2. Referenced Documents
2.1 ASTM Standards: 4.1 The breaking strength and elongation of the strand are
determined by one or more tensile tests in which fracture of the
A370 Test Methods and Definitions for Mechanical Testing
of Steel Products specimen ideally occurs in the free span.
4.2 Mechanical properties of the strand will be negatively
affected if proper care is not taken to prevent damage such as
These test methods are under the jurisdiction of ASTM Committee A01 on
severe bending, abrasion, or nicking of the strand during
Steel, Stainless Steel and Related Alloys and is the direct responsibility of
sampling.
Subcommittee A01.05 on Steel Reinforcement.
Current edition approved July 1, 2020. Published July 2020. Originally approved
4.3 Premature failure of the test specimens may result if
in 2009. Last previous edition approved in 2020 as A1061/A1061M – 20. DOI:
there is appreciable notching, cutting, or bending of the
10.1520/A1061_A1061M-20AE01.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or specimen by the gripping devices of the testing machine.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
4.4 Errors in testing will result if the wires constituting the
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. strand are not loaded uniformly.
*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
´1
A1061/A1061M − 20a
4.5 The mechanical properties of the strand will be materi- chuck devices or post-tensioning anchorages as the primary
ally affected by excessive heating during test specimen collec- gripping device shall be considered invalid. It shall be permis-
tion or preparation. sible to use chucking devices or post-tensioning anchorages as
a secondary gripping system, coupled with one of the methods
5. Apparatus
listed above, to prevent strand slippage.
5.1 Tensile testing machine calibrated in accordance with
NOTE 1—The number of teeth should be 10 to 30 per inch [25 mm].
Practices E4.
NOTE 2—The radius of curvature of the grooves should be approxi-
matelythesameastheradiusofthestrandbeingtested.Topreventthetwo
5.2 Class B-1 extensometer as described in Practice E83.
grips from closing tightly when the test specimen is in place, each groove
5.3 Class D extensometer as described in Practice E83; shouldbelocated ⁄32 in.[0.79 mm]abovetheflatfaceofthegrip(seeFig.
1 1).
alternately, a linear dial gauge or ruler with precision of 6 ⁄16
in. [1.5 mm].
8. Speed of Testing
6. Sampling
8.1 The speed of testing shall not be greater than that at
which load and strain readings can be made accurately. Refer
6.1 Unless otherwise specified in the applicable specifica-
to speed of testing in Test Methods A370 on TestingApparatus
tion for the strand being tested, test specimens shall be taken
and Operations.
from the finished strand prior to packaging. The number of test
specimens shall be taken as specified in the applicable speci-
9. Test Procedures
fication for the strand being tested.
9.1 Yield Strength—As listed in 5.2, a Class B-1 extensom-
7. Gripping Devices
eter (Note 3) shall be used as described in Practice E83 with a
gauge length equal to or greater than the lay length of the
7.1 Due to inherent physical characteristics of individual
strand. Typically, an extensometer with a 24 in. [600 mm]
tensile testing machines, it is not practical to recommend a
gauge length is used.The force-elongation data collected while
universal gripping method that is suitable for all tensile testing
loading, when plotted, shall produce a smooth curve free of
machines. Therefore, it is necessary to determine which of the
irregular step-wise movements or other evidence of non-
methods of gripping described in 7.1.1 – 7.1.3 is most suitable
for the tensile testing machine available. The gripping devices uniform force-elongation loading of the test specimen. One of
the two following methods shall be used to correct for gripper
shallbedesignedsuchthatduringtestingtheloadisdistributed
along the entire length of the grips. The minimum effective seating losses and other sources of elongation error normally
present during the initial loading of the test specimen.
grippinglengthshouldbeequaltoorgreaterthanthelaylength
of the strand. 9.1.1 Preload Method—After loading the specimen in the
test frame, apply and hold an initial load of 10 % of the
7.1.1 Standard V-Grips with Serrated Teeth (Note 1).
7.1.2 Standard V-Grips with Serrated Teeth (Note 1), Using required minimum breaking strength. Next, attach the exten-
someter described in 5.2 and adjust it to a reading of 0.1 % of
Cushioning Material—In this method, material is placed be-
tween the grips and the test specimen to minimize the notching the extensometer gauge length. Resume loading until the
extensometer indicates a total extension of 1.0 % of the
effect of the teeth. Materials that have been used include, but
are not limited to lead foil, aluminum foil, carborundum cloth, extensometer gauge length (a change in extension equal to 0.9
% of the extensometer gauge length, relative to the reading of
and brass shims. The type and thickness of material required is
dependent on the shape, condition, and coarseness of the teeth. 0.1 % of gauge length, is required to obtain a total extension of
1.0 % of the gauge length). Record the load at 1.0 % extension
7.1.3 Special Grips with Semi-Cylindrical Grooves (Note 2,
Fig. 1)—The grips can be used as is or in conjunction with an as the yield strength. The extensometer should remain attached
to the strand until at least 1.05 % EULis reached to ensure the
abrasive medium (typically, a slurry or coating) applied to
yield strength is accurately measured and recorded; typically,
preventslippagetothegroovesofthegrips,thegrippedportion
the extensometer is then removed from the specimen to avoid
of the test specimen, or both.
possible extensometer damage due to strand rupture.
7.1.4 Chucking Devices—Use of chucking devices of the
type generally used for applying tension to strands in casting 9.1.2 Elastic Modulus Extrapolation Method—Use a com-
puterized data acquisition system with a software-based test
beds or post-tensioning anchorages shall not be used as
primary gripping devices for testing purposes. Tests involving procedure to calculate the elastic modulus of the specimen as
load is applied.The calculation of the elastic modulus shall use
either the actual cross-sectional area of the specimen or the
nominal cross-sectional area as defined in the applicable
specification for the size and grade of strand being tested. The
elastic modulus shall be calculated using a sum-of-least-
squares linear regression in the linear-elastic portion of the
curve. To prevent errors potentially introduced during the
initial loading phase, the linear regression shall not utilize data
points measured until a minimum of 20 % of the minimum
1 breaking strength is reached. Also, to safely avoid the non-
FIG. 1 Note the ⁄32 in. [0.79 mm] Spacing Between the Flat Face
and the Radius of the Grip linear elastic portion of the force-elongation curve as the
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A1061/A1061M − 20a
yielding process starts, the linear regression shall not use data invalid. However, if all values meet or exceed the specified
points collected after 65 % of the minimum breaking strength minimums, the results shall be accepted (Note 4). Test results
is reached. Data corresponding to at least 70 % of the range from specimens that fracture within secondary chucking de-
between 20 % and 65 % of the minimum breaking strength vices shall be considered invalid regardless of whether mini-
(inclusive) shall be used for the linear regression used to mum values are satisfied. Material for which specimens break
calculate the elastic modulus. Once the elastic modulus is outside the gripping jaws and do not meet the minimum
determined, the force-elongation curve shall be extrapolated specified values are subject to additional tests according to the
using the measured slope of the elastic modulus to identify the applicable specification.
intersection with the elongation axis zero force point. This is
9.3.2 Wire Slip—Gripping systems shall securely grip all
the origin from which the 1.0 % EUL shall be determined.
outer wires and, in the case of 7-wire strand, the center wire
Record the yiel
...