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GB/T 21839-2019 (GBT 21839-2019)

Chinese standards (related to): 'GB/T 21839-2019'
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GB/T 21839-2019English440 Add to Cart 0--3 minutes. Auto immediate delivery. Test methods of steel for prestressing concrete GB/T 21839-2019 Valid GBT 21839-2019
GB/T 21839-2008English185 Add to Cart 0--3 minutes. Auto immediate delivery. Steel for prestressed concrete -- Test methods GB/T 21839-2008 Obsolete GBT 21839-2008


   
BASIC DATA
Standard ID GB/T 21839-2019 (GB/T21839-2019)
Description (Translated English) Test methods of steel for prestressing concrete
Sector / Industry National Standard (Recommended)
Classification of Chinese Standard H49
Classification of International Standard 77.140.65
Word Count Estimation 30,367
Date of Issue 2019-06-04
Date of Implementation 2020-05-01
Older Standard (superseded by this standard) GB/T 21839-2008
Drafting Organization China Metallurgical Construction Research Institute Co., Ltd., Changshu Longteng Rolling Body Manufacturing Co., Ltd., Liaoning Tongda Building Materials Industry Co., Ltd., Tianjin Yinlong Prestressed Material Co., Ltd., Tianjin Metallurgical Group Zhongxing Shengda Steel Co., Ltd., Beijing Tieke Shougang Track Technology Co., Ltd., Huludao North Metal Products Co., Ltd., Tianjin Iron and Steel Group Co., Ltd., Metallurgical Industry Information Standards Institute
Administrative Organization National Steel Standardization Technical Committee (SAC/TC 183)
Regulation (derived from) National Standard Announcement No.7 of 2019
Proposing organization China Iron and Steel Association
Issuing agency(ies) State Administration of Markets and China National Standardization Administration


GB/T 21839-2019: PDF in English (GBT 21839-2019)
GB/T 21839-2019
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.140.65
H 49
Replacing GB/T 21839-2008
Test methods of steel for prestressing concrete
(ISO 15630-3:2010, Steel for the reinforcement and prestressing of concrete –
Test methods – Part 3: Prestressing steel, MOD)
ISSUED ON: JUNE 04, 2019
IMPLEMENTED ON: MAY 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 4 
1 Scope ... 6 
2 Normative references ... 6 
3 Symbols and description ... 7 
4 General requirements for specimen ... 9 
5 Tensile test ... 9 
6 Bending test ... 12 
7 Repeated bending test ... 13 
8 Torsion test ... 14 
9 Winding and coating adhesion test ... 15 
10 Isothermal relaxation test ... 15 
11 Axial force fatigue test ... 20 
12 Stress corrosion test in thiocyanate solution ... 22 
13 Deflection tensile test ... 25 
14 Chemical analysis ... 29 
15 Geometry measurement ... 29 
16 Determination of relative rib area (fR) ... 32 
17 Determination of the deviation of nominal mass per meter ... 34 
18 Testing of anti-corrosion grease content ... 35 
19 Sheath thickness measurement ... 36 
20 Coating uniformity test ... 36 
21 Zinc layer quality test ... 36 
22 Test report ... 37 
Appendix A (Informative) List of comparisons between this standard and ISO
15630-3:2010 ... 38 
Appendix B (Informative) The technical differences between this standard and
ISO 15630-3:2010 and their reasons ... 39 
Appendix C (Informative) Tensile test method of steel strand for prestressed
concrete ... 40 
Test methods of steel for prestressing concrete
1 Scope
This standard specifies the test methods for the tensile, bending, repeated
bending, torsion, winding and coating adhesion, isothermal relaxation, axial
force fatigue, stress corrosion in thiocyanate solution, deflection tensile,
chemical analysis, measurement of geometric dimensions, determination of
relative rib area, determination of nominal mass deviation per meter, detection
of anti-corrosion grease content, measurement of sheath thickness, coating
uniformity, zinc layer quality and so on, of the steel for prestressing concrete.
This standard applies to the determination of the relevant properties of
prestressed steel wires, prestressed steel rods, prestressed steel bars,
prestressed steel strands.
2 Normative references
The following documents are essential to the application of this document. For
the dated documents, only the versions with the dates indicated are applicable
to this document; for the undated documents, only the latest version (including
all the amendments) are applicable to this standard.
GB/T 228.1 Metallic materials - Tensile testing - Part 1 : Method of test at
room temperature (GB/T 228.1-2010, ISO 6892-1:2009, MOD)
GB/T 230.1 Metallic materials - Rockwell hardness test - Part 1: Test method
(GB/T 230.1-2018, ISO 6508-1:2016, MOD)
GB/T 232 Metallic materials - Bend test (GB/T 232-2010, ISO 7438:2005,
MOD)
GB/T 238 Metallic materials – Wire - Reverse bend test (GB/T 238-2013,
ISO 7801:1984, MOD)
GB/T 239.1 Metallic materials - Wire - Part 1: Simple torsion test (GB/T
239.1-2012, ISO 7800:2003, MOD)
GB/T 1839 Test method for gravimetric determination of the mass per unit
area of galvanized coatings on steel products (GB/T 1839-2008, ISO
1460:1992, MOD)
accordance with the requirements of GB/T 228.1.
When measuring the total elongation at maximum force (Agt) of steel wire and
steel rod by manual method, draw equidistant marks on the free length of the
specimen (see GB/T 228.1); the distance between the marks is determined
according to the diameter of the sample, which can be 20 mm, 10 mm or 5 mm.
5.2 Test equipment
The test equipment shall be checked and calibrated according to GB/T 16825.1.
It shall have at least level 1 accuracy.
When measuring E, Fp0.1 or Fp0.2, the accuracy of the extensometer shall be
level 1 (see GB/T 12160); the extensometer used to determine Agt can be level
2 (see GB/T 12160).
Appropriate fixtures shall be used to prevent the specimen from breaking in or
near the fixture.
5.3 Test procedure
5.3.1 Overview
5.3.1.1 The tensile test shall be performed in accordance with the requirements
of GB/T 228.1. The tensile test procedure of multi-wire steel strands for
prestressed concrete can be performed with reference to Appendix C.
5.3.1.2 An extensometer shall be used to determine the modulus of elasticity
(E), 0.1% yield strength, 0.2% yield strength (Fp0.1 and Fp0.2), total elongation at
maximum force (Agt). The gauge distance of the extensometer is determined in
accordance with the requirements of relevant product standards.
5.3.1.3 The precise value of Agt can only be measured by the use of an
extensometer. If the extensometer on the specimen cannot be maintained until
the specimen breaks, the Agt can be determined as follows:
- Continue loading until the elongation recorded by the extensometer is
slightly greater than the elongation at Fp0.2. At this time, remove the
extensometer and record the distance between the upper and lower
working platforms of the testing machine. Continue to load until the
specimen breaks; record the final distance between the upper and lower
working platforms of the testing machine at this time.
- Calculate the difference of the distance between the upper and lower
working platforms of the two testing machines; add the ratio of this
difference to the initial distance between the upper and lower working
platforms of the testing machine and the percentage measured with the
D - Diameter of the mandrel.
Figure 1 -- Principle of bending equipment
6.2.2 The bending test can also be carried out according to GB/T 232 by a
device which is equipped with a support and a mandrel.
6.3 Test procedure
The bending test shall be carried out at a temperature of 10 °C ~ 35 °C; the
specimen shall be bent along the mandrel.
The bending angle and mandrel diameter shall meet the requirements of
relevant product standards.
6.4 Judgment of test results
The determination of the results of the bending test shall meet the requirements
of the relevant product standards.
When the product standard does not specify, if there are no visible cracks in the
bent part, the specimen is judged to be qualified.
Surface cracks produced on the roots of ribs or notches are valid tests. The
crack depth shall not be greater than the crack width.
7 Repeated bending test
7.1 Specimen
In addition to complying with the provisions of Chapter 4, the preparation of
specimen shall comply with the relevant requirements in GB/T 238.
7.2 Test equipment
The test equipment shall meet the relevant requirements in GB/T 238.
For steel wire with a nominal diameter of 10 mm < d ≤ 12.5 mm, the instrument
shall meet the following conditions: r = (30 ± 1) mm, h = 125 mm, dg = 11 mm
or 13 mm, as shown in Figure 2.
8.3.1 Torsion test shall be carried out in accordance with GB/T 239.1.
8.3.2 The torsion rate used is not more than 30 r/min.
8.3.3 The axial tension used is 0.5% ~ 2% of the corresponding tensile load of
the nominal tensile strength of the specimen.
9 Winding and coating adhesion test
9.1 Specimen
The specimen shall meet the requirements of Chapter 4.
9.2 Test equipment
The test equipment shall comply with the relevant requirements in GB/T 2976.
9.3 Test procedure
The winding and coating adhesion test shall be carried out in accordance with
the requirements of GB/T 2976.
10 Isothermal relaxation test
10.1 Test principle
The isothermal stress relaxation test is to keep the specimen at a certain length
(L0 + ΔL0) at a given temperature (unless otherwise specified, usually 20 °C);
starting from the initial force F0, measure the change of the force on the
specimen (see Figure 3).
In a given time, the loss of force is expressed as a percentage of the initial force.
10.3.1 Frame
Any deformation of the frame shall be within the limit that does not affect the
test results.
10.3.2 Force measuring device
10.3.2.1 Coaxial load cells or other suitable devices can be used. (Example:
Lever type loading system)
10.3.2.2 The load cell shall be calibrated in accordance with GB/T 16825.1; its
accuracy is ±1% when it is not greater than 1000 kN and ±2% when it is greater
than 1000 kN. Any other suitable device shall have the same accuracy as
specified for the load cell above.
10.3.2.3 The output resolution of the force measuring device shall not be less
than 5 × 10-4F0.
10.3.3 Length measuring device (extensometer)
The gauge length L0 is not less than 200 mm, especially for steel strands, when
the actual length L0 + ΔL0 of the same steel wire in the steel strand is measured,
the gauge length should be 1000 mm or an integer multiple of the strand lay
length.
The accuracy of the extensometer shall be level 1.
10.3.4 Clamping device