SIST EN ISO 15630-3:2025

SLOVENSKI STANDARD
01-oktober-2025
Jeklo za armiranje in prednapenjanje betona - Metode preskušanja - 3. del: Jeklo
za prednapenjanje (ISO 15630-3:2025)
Steel for the reinforcement and prestressing of concrete - Test methods - Part 3:
Prestressing steel (ISO 15630-3:2025)
Stahl für die Bewehrung und das Vorspannen von Beton - Prüfverfahren - Teil 3:
Spannstahl (ISO 15630-3:2025)
Aciers pour l'armature et la précontrainte du béton - Méthodes d'essai - Partie 3: Aciers
de précontrainte (ISO 15630-3:2025)
Ta slovenski standard je istoveten z: EN ISO 15630-3:2025
ICS:
77.140.15 Jekla za armiranje betona Steels for reinforcement of
concrete
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 15630-3
EUROPEAN STANDARD
NORME EUROPÉENNE
June 2025
EUROPÄISCHE NORM
ICS 77.140.15 Supersedes EN ISO 15630-3:2019
English Version
Steel for the reinforcement and prestressing of concrete -
Test methods - Part 3: Prestressing steel (ISO 15630-
3:2025)
Aciers pour l'armature et la précontrainte du béton - Stahl für die Bewehrung und das Vorspannen von
Méthodes d'essai - Partie 3: Aciers de précontrainte Beton - Prüfverfahren - Teil 3: Spannstahl (ISO 15630-
(ISO 15630-3:2025) 3:2025)
This European Standard was approved by CEN on 29 May 2025.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 15630-3:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 15630-3:2025) has been prepared by Technical Committee ISO/TC 17 "Steel" in
collaboration with Technical Committee CEN/TC 459/SC 4 “Concrete reinforcing and prestressing
steels” the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by December 2025, and conflicting national standards
shall be withdrawn at the latest by December 2025.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 15630-3:2019.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 15630-3:2025 has been approved by CEN as EN ISO 15630-3:2025 without any
modification.
International
Standard
ISO 15630-3
Fourth edition
Steel for the reinforcement and
2025-06
prestressing of concrete — Test
methods —
Part 3:
Prestressing steel
Aciers pour l'armature et la précontrainte du béton — Méthodes
d'essai —
Partie 3: Aciers de précontrainte
Reference number
ISO 15630-3:2025(en) © ISO 2025

ISO 15630-3:2025(en)
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 15630-3:2025(en)
Contents Page
Foreword .vi
Introduction .vii
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
3.1 Terms and definitions .1
3.2 Symbols .2
4 General provisions concerning test pieces . 3
5 Tensile test . 4
5.1 Test piece .4
5.2 Test equipment .4
5.3 Test procedure .4
5.3.1 General .4
5.3.2 Determination of the modulus of elasticity .5
6 Bend test . 6
6.1 Test piece .6
6.2 Test equipment .6
6.3 Test procedure .6
6.4 Interpretation of test results .6
7 Reverse bend test . 7
7.1 Test piece .7
7.2 Test equipment .7
7.3 Test procedure .8
8 Wrapping test . 8
8.1 Test piece .8
8.2 Test equipment .8
8.3 Test procedure .8
9 Isothermal stress relaxation test . . 8
9.1 Principle of test .8
9.2 Test piece .9
9.3 Test equipment .9
9.3.1 Frame .9
9.3.2 Force-measuring device . .9
9.3.3 Length-measuring device (extensometer) .10
9.3.4 Anchoring device.10
9.3.5 Loading device . . .10
9.4 Test procedure .10
9.4.1 Provisions concerning the test piece .10
9.4.2 Application of force .10
9.4.3 Initial force .11
9.4.4 Force during the test .11
9.4.5 Maintenance of strain .11
9.4.6 Temperature .11
9.4.7 Frequency of force recording . 12
9.4.8 Frequency of strain recording . 12
9.4.9 Duration of the test . 12
10 Axial force fatigue test .12
10.1 Principle of test . 12
10.2 Test piece . 13
10.3 Test equipment . 13
10.4 Test procedure . 13

iii
ISO 15630-3:2025(en)
10.4.1 Provisions concerning the test piece . 13
10.4.2 Stability of force and frequency . 13
10.4.3 Counting of force cycles .14
10.4.4 Frequency .14
10.4.5 Temperature .14
10.4.6 Validity of the test .14
11 Stress corrosion test in a solution of thiocyanate . 14
11.1 Principle of test .14
11.2 Sample and test piece .14
11.3 Test equipment .14
11.3.1 Frame .14
11.3.2 Force-measuring device . . .14
11.3.3 Time-measuring device . 15
11.3.4 Test cell containing the test solution . 15
11.3.5 Test solution . 15
11.4 Test procedure . 15
11.4.1 Provisions concerning the test pieces . 15
11.4.2 Application and maintenance of force .16
11.4.3 Filling of the test cell .16
11.4.4 Temperature during the test .16
11.4.5 Termination of the test .16
11.4.6 Determination of median lifetime to fracture .16
12 Deflected tensile test.16
12.1 Principle of test .16
12.2 Sample and test pieces .16
12.3 Test equipment .17
12.3.1 General description . .17
12.3.2 Dimensions .17
12.3.3 Anchorages .17
12.3.4 Mandrel .18
12.3.5 Loading device . . .19
12.4 Test procedure .19
13 Chemical analysis . .20
14 Measurement of the geometrical characteristics .20
14.1 Test piece . 20
14.2 Test equipment . 20
14.3 Test procedures . 20
14.3.1 Rib measurements . 20
14.3.2 Indentation measurements .21
14.3.3 Lay length of strand (P) . 22
14.3.4 Straightness . 22
15 Determination of the relative rib area (f ) .22
R
15.1 General . 22
15.2 Calculation of f . 23
R
15.2.1 Relative rib area . 23
15.2.2 Simplified formulae . 23
15.2.3 Formula used for the calculation of f .24
R
16 Determination of deviation from nominal mass per metre .24
16.1 Test piece .24
16.2 Accuracy of measurement .24
16.3 Test procedure . 25
17 Test report .25
Annex A (informative) Options for agreement between the parties involved .26
Annex B (informative) Stress corrosion test in thiocyanate solution with galvanostatic current .27

iv
ISO 15630-3:2025(en)
Annex C (informative) Stress corrosion test in distilled water .33
Bibliography .38

v
ISO 15630-3:2025(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 17, Steel, Subcommittee SC 16, Steels for the
reinforcement and prestressing of concrete,in collaboration with the European Committee for Standardization
(CEN) Technical Committee CEN/TC 459/SC 4, ECISS - European Committee for Iron and Steel Standardization,
in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This fourth edition cancels and replaces the third edition (ISO 15630-3:2019), which has been technically
revised.
The main changes are as follows:
— addition of the informative Annex B which specifies a stress corrosion test in thiocyanate solution with
galvanostatic current;
— addition of the informative Annex C which specifies a stress corrosion test in distilled water.
A list of all parts in the ISO 15360 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

vi
ISO 15630-3:2025(en)
Introduction
The aim of the ISO 15630 series is to provide all relevant test methods for reinforcing and prestressing
steels in one standard series.
This document covers standard test methods, as well as specialized test methods that are not commonly
used in routine testing and that should only be considered where relevant (or specified) in the applicable
product standard.
Reference is made to International Standards on the testing of metals, in general, as they are applicable.
Complementary provisions have been given if needed.
A list of options for agreement between the parties involved is provided in Annex A.

vii
International Standard ISO 15630-3:2025(en)
Steel for the reinforcement and prestressing of concrete —
Test methods —
Part 3:
Prestressing steel
1 Scope
This document specifies test methods applicable to prestressing steel (bar, wire or strand) for concrete.
This document does not cover the sampling conditions that are dealt with in the product standards.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 4957, Tool steels
ISO 4965-1, Metallic materials — Dynamic force calibration for uniaxial fatigue testing — Part 1: Testing systems
ISO 4965-2, Metallic materials — Dynamic force calibration for uniaxial fatigue testing — Part 2: Dynamic
calibration device (DCD) instrumentation
ISO 6508-1, Metallic materials — Rockwell hardness test — Part 1: Test method
ISO 6892-1, Metallic materials — Tensile testing — Part 1: Method of test at room temperature
ISO 7500-1, Metallic materials — Calibration and verification of static uniaxial testing machines — Part 1:
Tension/compression testing machines — Calibration and verification of the force-measuring system
ISO 7801, Metallic materials — Wire — Reverse bend test
ISO 7802, Metallic materials — Wire — Wrapping test
ISO 9513, Metallic materials — Calibration of extensometer systems used in uniaxial testing
ISO 16020, Steel for the reinforcement and prestressing of concrete — Vocabulary
3 Terms, definitions and symbols
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 16020 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/

ISO 15630-3:2025(en)
3.2 Symbols
For the purposes of this document, the following symbols apply.
Symbol Unit Description Reference
a mm Rib height at the mid-point 14.3, 15.2
m
a mm Maximum height of rib or depth of indentation 14.3
max
a mm Average height of a portion i of a rib subdivided into p parts of length Δl 15.2
s,i
a mm Rib height at the quarter-point 14.3, 15.2
1/4
a mm Rib height at the three-quarters point 14.3, 15.2
3/4
A % Percentage elongation after fracture 5.1, 5.3
A % Percentage total extension at maximum force Clause 5
gt
A % Percentage uniform elongation after fracture 5.3
r
b mm Width of transverse rib at the mid-point 14.3.1.6
c mm Rib or indentation spacing 14.3
C mm Groove width at nominal diameter of the mandrel, d , used for the deflected 12.3.4
a
tensile test
d mm Nominal diameter of the bar, wire or strand 5.3.1, 7.2, Table 3,
10.4.6, Table 4
d mm Nominal diameter of the mandrel used for the deflected tensile test 12.3.4
a
d mm Diameter to be obtained after placing two gauge cylinders in the groove of the 12.3.4
b
mandrel used for the deflected tensile test
d mm Diameter of the gauge cylinder used for the deflected tensile test 12.3.4
e
d mm Diameter of guide hole 7.2
g
d mm Inner diameter of the groove of the mandrel used for the deflected tensile test 12.3.4
i
D % Average coefficient of reduction of the maximum force in the deflected tensile 12.2, 12.4
test
D mm Inner diameter of the test cell in the stress corrosion test 11.3.4
c
D % Individual percentage of reduction of the maximum force in the deflected 12.4
i
tensile test
D mm Diameter of the mandrel of the bending device in the bend test Figure 2
m
e mm Average gap between two adjacent ribs or indentation rows 14.3.1.4, 14.3.2.5
E MPa Modulus of elasticity 5.2, 5.3
f Hz Frequency of force cycles in the axial force fatigue test 10.1, 10.4.2
f — Relative rib area Clause 15
R
F N Individual breaking force in the deflected tensile test 12.4
a,i
F N Maximum force in the tensile test 5.3
m
N Mean value of the maximum force 9.2, 11.2, 12.2,
F
m
12.4
F N 0,1 % proof force, plastic extension 5.2, 5.3
p0,1
F N 0,2 % proof force, plastic extension 5.2, 5.3
p0,2
F N Force range in the axial force fatigue test Figure 6, 10.3,
r
10.4.2
F N Residual force in the test piece at time t in the isothermal stress relaxation 9.1
rt
test
ΔF N Force loss in the test piece at time t in the isothermal stress relaxation test 9.1
rt
F mm Area of longitudinal section of one rib 15.2
R
F N Upper force in the axial force fatigue test Figure 6, 10.3,
up
10.4.2
ISO 15630-3:2025(en)
Symbol Unit Description Reference
F N Initial force in the isothermal stress relaxation test and the stress corrosion 9.1, 9.2, 9.3, 9.4,
test 11.1, 11.2, 11.4.2
G mm Depth of the groove of the mandrel used for the deflected tensile test 12.3.4
h mm Distance from the top tangential plane of cylindrical supports to the bottom 7.2
face of the guide
h mm Bow height in the plane of the bow 14.3.4
b
l mm Length of indentation 14.3.2.4
L mm Length of the test piece in the stress corrosion test 11.2
t
L mm Gauge length (without force on the test piece) in the isothermal stress relaxa- 9.1, 9.3, 9.4
tion test
11.2, 11.3.4,
Length of the test piece in contact with the solution in the stress corrosion 11.4.1, 11.4.3,
test 11.4.5
L mm Length of the passive side in the deflected tensile test 12.3.2
L mm Length of the active side in the deflected tensile test 12.3.2
m, n — Coefficients or numbers 9.4.9, 14.3, 15.2
P mm Lay length of a strand 14.3.3
ρ % Relaxation 9.4.9
r mm Radius of cylindrical supports 7.2
R mm Radius at the base of the mandrel used for the deflected tensile test 12.3.4
r mm Distance between the grips and the gauge length for the manual measure- 5.3
ment of A
gt
r mm Distance between the fracture and the gauge length for the manual measure- 5.3
ment of A
gt
R µm Surface roughness of the mandrel used for the deflected tensile test 12.3.4
a
S mm Nominal cross-sectional area of the test piece 5.3.2
n
t h Time for relaxation test 9.4.9
t h Maximum agreed time for the stress corrosion test 11.4.5
a
t h Individual lifetime to fracture in the stress corrosion test 11.4.5
f,i
t h Median lifetime to fracture in the stress corrosion test 11.4.6
f,m
t s Starting time in the isothermal stress relaxation test and in the stress corro- 9.4.2, 11.4
sion test
y mm Distance from a plane, defined by the axes of the cylindrical supports, to the Figure 3
nearest point of contact with the test piece
V mm Volume of test solution to fill the test cell in the stress corrosion test 11.4.3
Z % Percentage reduction of area 5.3.1
α ° Angle of deviation in the deflected tensile test 12.3.2
β ° Rib or indentation angle to the bar or wire axis 14.3
— Value of the strain for a force equal to x F 5.3.2
ε
m
xF
m
ρ % Relaxation 9.4.9
14.3.1.4, 14.3.2.5,
∑e mm Part of the circumference without indentation or rib
i
15.2
NOTE 1 MPa = 1 N/mm .
4 General provisions concerning test pieces
Unless otherwise agreed or specified in the product standard, the samples shall be taken from the finished
product before packaging.
ISO 15630-3:2025(en)
Special care should be taken when samples are taken from the packaged product (e.g. coil or bundle) in order
to avoid plastic deformation, which can change the properties of the samples used to provide the test pieces.
Specific complementary provisions concerning the test pieces are indicated in the relevant clauses of this
document, if needed.
5 Tensile test
5.1 Test piece
In addition to the general provisions given in Clause 4, the free length of the test piece shall be sufficient for
the determination of the percentage total extension at maximum force (A ) in accordance with 5.3.1.
gt
If the percentage elongation after fracture (A) is determined manually, the test piece shall be marked in
accordance with ISO 6892-1.
If the percentage total extension at maximum force (A ) is determined by the manual method for a bar or
gt
wire, equidistant marks shall be made on the free length of the test piece (see ISO 6892-1). The distance
between the marks shall be 20 mm, 10 mm or 5 mm, depending on the test piece diameter.
5.2 Test equipment
The test equipment shall be verified and calibrated in accordance with ISO 7500-1 and shall be at least of
class 1.
If an extensometer is used, it shall be of class 1 in accordance with ISO 9513 for the determination of E, F
p0,1
or F ; for the determination of A , a class 2 extensometer (see ISO 9513) may be used.
p0,2 gt
Grips shall be such as to avoid breaks in or very near the grips.
5.3 Test procedure
5.3.1 General
The tensile test for the determination of the modulus of elasticity (E), 0,1 % and 0,2 % proof force (F and
p0,1
F ), maximum force (F ), percentage total extension at maximum force (A ) and/or percentage elongation
p0,2 m gt
after fracture (A) and percentage reduction of area (Z) shall be performed in accordance with ISO 6892-1.
An extensometer shall be used for the determination of the modulus of elasticity (E), 0,1 % and 0,2 % proof
force (F and F ) and percentage total extension at maximum force (A ). The extensometer gauge
p0,1 p0,2 gt
length shall be as specified in the relevant product standard.
Accurate values of A can only be obtained with an extensometer. If it is not possible to leave the
gt
extensometer on the test piece to fracture or until the maximum force has been passed, the extension may
be measured as follows.
— Continue loading until the extensometer records an extension just greater than the extension
corresponding to F , at which the extensometer is removed; the distance between the testing machine
p0,2
crossheads is noted. The loading is continued until fracture occurs. The final distance between the
crossheads is noted.
— The difference between the crosshead measurements is calculated as a percentage of the original distance
between the cross-heads and this value is added to the percentage obtained by the extensometer.

ISO 15630-3:2025(en)
For wire and bars, it is also permissible to determine A by the manual method. If A is determined by the
gt gt
manual method after fracture, A shall be calculated from Formula (1):
gt
AA=+R /2000 (1)
gt rm
where A is the percentage uniform elongation after fracture.
r
The measurement of A shall be made, as the measurement of A (see ISO 6892-1), on the longer of the two
r
fractured parts of the test piece on a gauge length of 100 mm, as close as possible to the fracture but at a
distance, r , of at least 50 mm or 2 d (whichever is the greater) away from the fracture. This measurement
may be considered as invalid if the distance, r , between the grips and the gauge length is less than 20 mm or
d (whichever is the greater). See Figure 1.

a
Grip length.
b
Gauge length 100 mm.
Figure 1 — Measurement of A by the manual method
gt
It is preferable to apply a preliminary force to the test piece, e.g. to about 10 % of the expected maximum
force before placing the extensometer.
If A is not completely determined with an extensometer, this shall be indicated in the test report.
gt
For routine tests conducted by prestressing steel producers, the test information should be described within
internal documentation.
Tensile properties (F , F , F ) are recorded in force units.
p0,1 p0,2 m
For the determination of percentage elongation after fracture (A), the original gauge length shall be
eight times the nominal diameter (d), unless otherwise specified in the relevant product standard. In case of
dispute, A shall be determined manually.
If the fracture occurs within a distance of 3 mm from the grips, the test shall, in principle, be considered as
invalid and it shall be
...