GB/T 28900-2022 English PDF (GB/T28900-2022)

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GB/T 28900-2022: Test methods of steel for reinforcement of concrete
GB/T 28900-2022
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.140.60
CCS H 44
Replacing GB/T 28900-2012
Test methods of steel for reinforcement of concrete
(ISO 15630-1:2019, Steel for the reinforcement and prestressing of
concrete - Test methods - Part 1: Reinforcing bars, rods and wire, MOD)
ISSUED ON: OCTOBER 12, 2022
IMPLEMENTED ON: OCTOBER 12, 2022
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 4
1 Scope ... 6
2 Normative references ... 6
3 Terms and definitions ... 7
4 Symbols and descriptions ... 7
5 General provisions concerning the test piece ... 8
5.1 Preparation ... 8
5.2 Straightening ... 8
5.3 Artificial aging ... 9
6 Tensile test ... 9
6.1 Test piece ... 9
6.2 Test equipment ... 10
6.3 Test procedure ... 10
7 Bending test ... 12
7.1 Test piece ... 12
7.2 Test equipment ... 13
7.3 Test procedure ... 13
7.4 Interpretation of test results ... 14
8 Rebending test ... 14
8.1 Test piece ... 14
8.2 Test equipment ... 14
8.3 Test procedure ... 15
8.4 Interpretation of test results ... 16
9 Axial force fatigue test ... 16
9.1 Test principle ... 16
9.2 Test piece ... 17
9.3 Test equipment ... 17
9.4 Test procedure ... 17
10 Chemical analysis ... 19
11 Dimension measurement ... 19
11.1 Test piece ... 19
11.2 Test equipment ... 19
11.3 Test procedure ... 20
12 Determination of the specific projected rib area (fR) ... 23
12.1 General ... 23
12.2 Measurement ... 23
12.3 Calculation ... 23
13 Determination of weight deviation ... 25
13.1 Test piece ... 25
13.2 Accuracy of measurement ... 25
13.3 Calculation ... 25
14 Cyclic inelastic load test ... 26
14.1 Test principle ... 26
14.2 Test piece ... 26
14.3 Test equipment ... 27
14.4 Test procedure ... 27
Appendix A (Informative) Comparison table of structure between this document and
ISO 15630-1:2019 ... 29
Appendix B (Informative) Technical differences and reasons between this document
and ISO 15630-1:2019 ... 31
Test methods of steel for reinforcement of concrete
1 Scope
This document specifies the test methods of tensile test, bending test, rebending test,
axial force fatigue test, chemical analysis, geometric dimension measurement,
determination of specific projected rib area, determination of weight deviation and
cyclic inelastic load test of steel for reinforcement of concrete.
This document applies to steel for reinforcement of concrete.
This document does not apply to prestressed steel products.
2 Normative references
The following documents are normatively referenced in this document and are
indispensable for its application. For dated references, only the version corresponding
to that date is applicable to this document; for undated references, the latest version
(including all amendments) is applicable to this document.
GB/T 228.1, Metallic materials - Tensile testing - Part 1: Method of test at room
temperature (GB/T 228.1-2021, ISO 6892-1:2019, MOD)
GB/T 232, Metallic materials - Bend test (GB/T 232-2010, ISO 7438:2005, MOD)
GB/T 4336, Carbon and low-alloy steel - Determination of multi-element contents -
Spark discharge atomic emission spectrometric method (routine method)
GB/T 11170, Stainless steel. Determination of multi-element contents - Spark
discharge atomic emission spectrometric method (Routine method)
GB/T 12160, Metallic materials - Calibration of extensometers systems used in
uniaxial testing (GB/T 12160-2019, ISO 9513:2012, IDT)
GB/T 16825.1, Metallic materials - Calibration and verification of static uniaxial
testing machines - Part 1: Tension/compression testing machines - Calibration and
verification of the force-measuring system (GB/T 16825.1-2008, ISO 7500-1:2004,
IDT)
GB/T 25917.1, Uniaxial fatigue testing systems - Part 1: Calibration of dynamic
force (GB/T 25917.1-2019, ISO 4965-1:2012, IDT)
GB/T 25917.2, Uniaxial fatigue testing systems - Part 2: Dynamic calibration device
(DCD) instrumentation (GB/T 25917.2-2019, ISO 4965-2:2012, IDT)
Note 1: For tensile test at room temperature, axial force fatigue test, cyclic inelastic
load test, bending test, rebending test, and determination of weight deflection,
the straightening of the test piece is critical.
Note 2: Excessive straightening can easily cause changes in mechanical and process
properties. Use a rubber hammer or a wooden hammer for slight knock, or a
special device for straightening. On the basis of ensuring the minimum plastic
deformation, try to make the axis of the test piece coincident with or in the
same plane as the line of action of the force.
5.3 Artificial aging
When determining the performance indicators in the tensile test at room temperature,
bending test, rebending test, axial force fatigue test and cyclic inelastic load test, the
straightened test piece can be artificially aged according to the requirements of the
product standard.
When the artificial aging process is not specified in the product standard, the following
process conditions can be used: heat the test piece to 100 °C; keep it warm at 100 °C ±
10 °C for 60 min ~ 75 min; then, cool it naturally in still air to room temperature.
Note: Different test conditions (including quantity and size of test pieces and type of
heating equipment) require different heating durations. It is generally believed
that the best effect is achieved when the heating duration is not less than 40 min.
If the test pieces are artificially aged, the process conditions of artificial aging shall be
recorded in the test report.
6 Tensile test
6.1 Test piece
In addition to the general provisions given in Chapter 5, the parallel length of the test
piece shall be long enough to meet the requirements for the determination of elongation
after break (A) or total elongation at maximum force (Agt) in 6.3.
When the elongation after break (A) is determined manually, the test piece shall be
marked with the original gauge length according to the provisions of GB/T 228.1.
When the total elongation at maximum force (Agt) is determined manually, equidistant
marks shall be marked on the parallel length of the test piece, where the length between
the marks shall be selected from 20 mm, 10 mm or 5 mm according to the diameter of
the test piece.
6.2 Test equipment
The testing machine shall be checked and calibrated according to GB/T 16825.1, and
its accuracy shall reach at least grade 1.
When an extensometer is used to measure ReL or Rp0.2, it shall be a grade 1 extensometer
(GB/T 12160); when it is used to measure Agt, it can be a grade 2 extensometer (GB/T
12160).
The extensometer which is used to determine the total elongation at maximum force
(Agt) shall have a gauge length of at least 100 mm, and the gauge length shall be
recorded in the test report.
6.3 Test procedure
6.3.1 General requirements
6.3.1.1 The tensile test shall be carried out in accordance with GB/T 228.1.
6.3.1.2 Unless otherwise specified in the relevant product standards, for the calculation
of tensile properties (ReL or Rp0.2, Rm), the original cross-sectional area shall be the
nominal cross-sectional area.
6.3.1.3 If the break occurs at a distance less than 20 mm from the clamping part or at
the nominal diameter d (whichever is greater) or on the clamping part, the test may be
considered...