The presentation is centered in a comparison of reinforcing steel bar standards of twenty countries / regions, selected on the base of rebar production, exports and application. The comparison includes mechanical properties (yield strength, tensile strength, elongation to rupture, uniform elongation, strain hardening ratio); chemical composition; special tests like fatigue and adherence, and other items.The evolution of the requirements along time is taken into account, too. The focus is on the seismic behavior of concrete reinforcing bar

1. Analysis of international standards
on concrete reinforcing steel bar
Jorge Madias (1), Michael Wright (2), Gustavo Behr (3), Vanessa Valladares (3)
(2) Modern Metal Consulting, Singapore
(1) metallon, San Nicolas, Argentina
(3) ADELCA, Aloag, Ecuador

2. Content
Introduction
Selected standards
Mechanical properties
Bending & rebending
Chemical analysis
Special tests
Conclusions

3. Introduction
metallon
Consulting & training company based in San
Nicolas, Argentina
Modern Metal Consulting
Consulting & training company based in Singapore
ADELCA
Steel company with two plants in Ecuador
Aloag: EAF, LF, Billet caster, Rebar rolling mills
Milagro: New rebar & wire rod rolling mill recently
started-up

4. Introduction
Standards usually reflect with a certain delay the
advances of technology in product manufacturing and
the growing requisites of the users
National, regional and international standards on steel
reinforcing bar are analyzed
Rebar standards: low degree of globalization
Aim of the study
1) Verify trends in the quality constraints that may affect
the commercialization and application of rebar
2) Specifically, requisites related with seismic behavior
and the influence of manufacturing processes (natural
hardness, on-line quenching and tempering, micro-
alloying)

5. Selected standards
 Reasons for country / region selection
 Rebar exporting potential
 High seismicity
 High rebar production
 Special features of the standard
 In some countries, a single standard cover not only rebar but
other long products for civil construction (generally round bars,
but in some cases welded mesh, pre-stress concrete, etc.)
 ASTM standards and their followers have usually two standards:
one for reinforcing bar in general, and other for weldable rebar
 Still there are in some countries standards for rebar produced by
rolling rail or strip scrap (not taken into account in this study)

6. Selected standards
Country Standard Character
Argentina IRAM-IAS U500-207 2004 Weldable
IRAM-IAS U500-528 2004 General
Australia/N. Zealand AS/NZS 4671:11 General
Brazil ABNT NBR7480 General
Canada G30.18-09EN reaffirmed 2014 General
Chile NCh 204 General
China GB 1499.2 2007 General
Colombia NTC 2289 2007 General
Ecuador NTE INEN 102:2015 General
NTE INEN 2167:2017 Weldable
Europe prEN 10080 2005 General
Germany DIN 488.1 2009 Grades, properties, marking
DIN 488.2 2009 General
DIN 488.6 2010 Conformity assessment
International ISO 6935-2 2015 Part 2 General
Japan JIS G3112 2010 General
Mexico NMX-C-407-ONNCCE-2001 General
NMX-B-457-Canacero-2013 Weldable
Peru PNTP 341 031 2015 General
PNTP 339 186 2015 Weldable
Spain UNE 36065 2011 High ductility
UNE 36068 2011 Weldable
Taiwan CNS 560 2005 General
Turkey TS 708 2010 General
United Kingdom BS 4429 2005 General
USA ASTM A 615-14 General
ASTM A 706-14 Weldable
Vietnam TCVN 1651-2 2008 General

7. Mechanical properties
Compared properties
Tensile and yield strength
Stress ageing ratio
Uniform elongation
Elongation to rupture
Yield strength
Present in all standards
Some standards define a
minimal value, others both
minimum and maximum
Lowest value 220 Mpa
Turkey, one grade
Maximum value 600 Mpa
ISO, one grade

8. Mechanical properties
Yield strength
Higher strength grades
0
100
200
300
400
500
600
700
Yieldstrenggth(MPa)

9. Mechanical properties
 Yield strength
 Some Asian countries are
considering the introduction
of 600 MPa minimum grade,
as in ISO standard
 Arguments favoring high
strength rebar from the point
of view of constructors
Reducing rebar
congestion in anti seismic
design, particularly in
column-beam crossings
Reducing total steel mass
needed for the overall
construction.

10. Mechanical properties
 Elongation
 Elongation to rupture is
preferred
 But uniform elongation starts
to make inroads
Elongation measured for
the maximum load, more
complex to measure
(extensometer is required)
German standard changed
to uniform elongation in
2009
China, Spain, Vietnam and
some grades of the Turkish
standard define minimum
uniform elongations

11. Mechanical properties
Elongation
Elongation to rupture vs. yield strength

12. Mechanical properties
 Elongation
 Uniform elongation
 Australia / New Zealand
standard: three ductility
degrees
 low (an L is added to the bar
designation);
 normal (an N is added to the
bar designation)
 high or seismic (an E is added
to the bar designation).
 Type E corresponds to 2
levels of minimum yield
strength (300 and 500 MPa)
 Very high uniform elongation
is requested (15 and 10%
respectively)
 Tensile strength / yield
strength ratio of at list 1.15
 Important for New Zealand
only

13. Mechanical properties
 The question is “why is 5% elongation to rupture considered
acceptable in higher yield strength rebar?”
 Experience suggests that the minimum acceptable elongation to
rupture (%) in rebar is dictated by what can reasonably be achieved in
a high yield strength steel made with simple C-Mn metallurgy
 But at what elongation to rupture would a metal be seen to be classed
as “brittle”?
 The reason for this question is that in a concrete-steel composite
material, the concrete is a brittle material – if the steel is also brittle,
then the entire structure can be classed as brittle. The ductile
properties can only originate in the steel, so this property must be
protected by Standards.

14. Mechanical properties
Tensile strength / yield strength ratio (strain hardening
ratio)
High value for some grades and low value (or no value) for
others
ISO, Australia/New Zealand, Brazil, USA, UK, Mexico, China,
Turkey
Only high values
Argentina, Canada, Chile, Colombia, Ecuador, Peru, Spain,
Japan
Highest ratio (>1.25)
ASTM A706, Argentina, Mexico NMX-B-457, Chile, Colombia,
Ecuador, Peru (Taiwan, China just for some grades)
 >1.20 Spain (high ductility); Turkey (one grade); Canada
 >1.15 Australia/New Zealand for seismic grades
Single low value
Germany, >1.08

15. Mechanical properties
Tensile strength / yield strength ratio
Relation with elongation to rupture

16. Mechanical properties
 Bending and rebending
 Most standards: bending to 180º
 Mandrel diameter function of bar
diameter
 Exception: Chile (90º bending)
 Some standards prefer 90º
bending only for the large diameter
bars and/or the very high strength
grades
 Bending and rebending (with
intermediate ageing)
 Spain, UK
 Germany (for bars <40 mm)
 Magnetized particles testing to
assess if cracks are present after
bending, common for other steel
products, still not considered by
rebar standards

17. Chemical analysis
 Generally, just maximum content for some elements
 Heat analysis and product analysis (usually 10% higher)
 Brazil, Chile: no spec required
 ASTM A615 and followers: only maximum P content
 ASTM A 706 (weldable rebar) and followers: maximum values
for C, Mn, P, S, Si and Ceq
 Same for high ductility / weldable rebar in other standards
 ISO, European countries, China, Argentina: N2<0.012%, for
some grades
 European standard: Cu<0.80 %; Germany <0.60%
 Canada: Mn, Si more restricted than usual for galvanized rebar
 Internal specifications of steel plants are always more restrictive
than those in the standards
 To make sure they obtain the required mechanical properties at
lower cost
 To minimize surface and internal quality problems, as those related
with high sulphur or high copper

18. Chemical analysis
 Lowest P 0.035
 ASTM (weldable rebar), Mexico, Colombia, Ecuador,
Peru
 Lowest S 0,040%
 ISO (weldable grades), one of the Ecuador standards,
four Japanese grades, two weldable grades in Taiwan
and Vietnam
 Lowest C 0.22%
 Europe, Spain, Germany
 Turkey, Argentina just for weldable rebar
 Mn: <1.50 to <1.80, just some standards
 Standards reflect with a long delay the advancement of
steelmaking technology
 Specs are relaxed; rejection is fairly uncommon
 Exception: weldable / high ductility rebar
 C, Mn, residuals are to a certain extent under control
 Trend to establish weldability / high ductility
requirements

19. Special tests
 Fatigue
 Not mentioned in ASTM standards and followers, and Chile, Taiwan, Turkey,
Vietnam
 Required by Germany, UK. Spain for high ductility rebar
 European standard: an option, but its application is very thoroughly detailed
 Argentina, China, Australia / New Zealand: may be agreed between purchaser and
manufacturer
 Adherence
 Not mentioned in most standards
 European standard
 Adherence given by the geometry of ribs, but that it can be verified by beam test or
pull test
 UK: same, but beam test as the alternative testing tool
 Australia / New Zealand
 Calculus for estimation of adherence in function of the surface of ribs
 Pull test as an alternative
Fatigue Beam test Pull test

20. Non-standard regulations
 Some governmental measures go beyond the standards regarding rebar
specifications
 Argentina, Ecuador: certification system for civil construction steel product
 In Europe this is included in the standards
 Influence of the mechanism utilized by the manufacturer to achieve the
required mechanical properties tends to be taken into account, as it influences
behavior in use (corrosion, fire strength, seismic behavior)
 Department of Building and Housing of New Zealand issues Practice Advisory that
establish how to use the anti seismic grade rebar, taking into account if it was
produced using microalloying or on-line quenching and tempering [36]. For example
(MA means microalloyed and QT means on-line quenched and tempered)
 Cold re-bending/straightening Grade 500E MA and QT not permitted by NZS 3109.
 Welding of Grade 500E QT is not permitted by NZS 3109.
 Site welding of Grade 500E MA should be avoided.
 Shop welding (but not tack welding) of Grade 500E MA is considered acceptable
provided that evidence is presented that the procedures used do not affect
compliance of the reinforcement with AS/NZS 4671
 In certain countries, not only the producer name or logo must be rolled in the
bar, but the name of the importing company, is such is the case
 Foreign manufacturers introducing rebar in Germany must roll in the rebar a
specific mark given by a local association

21. Conclusions
 Trends
 Mechanical properties
 Introduction of higher high yield grades, over 500 MPa, aiming to decrease bar
congestion, particularly in column / beam crossings in high-rise buildings for seismic
zones
 Introduction of uniform elongation
 Higher minimum elongation is high seismicity countries
 Strain ageing ratio
 Consensus, for high seismicity countries, in >1.15 or higher
 Bending
 European-influenced standards prefer bending and rebending.
 Chemical analysis
 Low C and low Ceq for weldable / high ductilty grades
 In some countries, particularly in Europe, only weldable / high ductility grades exist
 Most critical chemistry requirements are low C (<0.22-<0.25%), and N2<120 ppm
 Others
 Fatigue and adherence testing start to occur as a requisite in some European
standards
 Grain size mentioned in the Chinese standard
 Traceability more relevant, taking into account intervention of several manufacturers
of different countries for a given product

22. Conclusions
 Updating rebar standards
 Introduction of minimum uniform elongation, rather than elongation
to rupture, as a more fundamental requisite for seismic / high
ductility purposes.
 Introduction of magnetized particles testing to assess if cracks are
present after bending
 Maximum grain size should be considered for seismic / high
ductility purposes
 Lower phosphorus and sulphur contents.
 As international trade of billets intended for rebar rolling becomes
more important, traceability should be emphasized.
 Request of conformity assessment by third parties
 Hardening mechanism utilized by the manufacturer to obtain the
properties becomes more important, as it influences performance
(loss of properties, corrosion, seismic behavior, strength after fire)

23. Jorge Madias (1), Michael Wright (2), Gustavo Behr (3), Vanessa Valladares (3)
(1) metallon, San Nicolas, Argentina
(2) Modern Metals Consulting, Singapore
Modern Metal Consulting
(3) ADELCA, Aloag, Ecuador