Continuous Galvanized Rebar

Zinc…essential for life
New Solution/Application
Continuous Galvanized Rebar
Frank E. Goodwin Sc.D.
IZA International Galvanizing Conference and
Exhibition
Delhi, India
July 10-11, 2014
Zinc…essential for life
Contents
• The Problem, and Our Approach
• Development Assistance to Xiamen
Newsteel (XNS-China) and Super
Galvanising (SG-Dubai)
• Worldwide Developments
Zinc…essential for life
The Problem with Rebar
Initially: Cosmetic Staining
Later: Structural Weakening
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Cape Town sea wall
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Research and Field Experience
Compared to black steel, galvanized
rebar provides:
•  significant delay in the initiation
of corrosion of the zinc coating;
•  long-term protection until coating
is dissolved and totally lost;
•  sacrificial cathodic protection of exposed
areas of steel.
Zinc…essential for life
Protecting RebarAvailable Products
Epoxy Coating: strictly a
barrier coating – any cuts in
the epoxy coating give a
pathway to corrosionvulnerable to damage, in
handling or service,
unrepaired cut ends
Stainless Clad: barrier
protection similar to epoxy,
but more resistant to
handling damage, 2.6-3.2X
black rebar cost
Zinc…essential for life
Protecting RebarAvailable Products
Batch Galvanized:
Sacrificial and barrier
protection offered at 2X
rebar cost, must be
formed before coating
Zn Spraying followed by
Epoxy Coating (Gerdau
Ameristeel Z-Bar): A
semi-continuous process,
moving in right direction
but still costly (requires
manufacture of Zn wire)
Zinc…essential for life
Coating Alternatives
CRG and CGR + Epoxy Very
Competitive
Epoxy Only
(ECR)
Batch
Galv. (BGR)
316
SS-Clad
316
Solid SS
Continuous
Galv. (CGR)
CGR
+ Epoxy
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Batch Galvanized Rebar (BGR)
Uses pure Zn: the flux technology is well-developed (zincammonium chloride)
Produced to ASTM A767:
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Our Approach
Continuous Galvanized Rebar (CGR)
• Reduce cost so that we can better compete
with ECR
• Keep advantage of Zn coating of BGR
• Introduce other advantages, including
bending after coating on customer’s site
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Our unique process
Use Al-containing Zn bath to control of coating structure
Use of Al-tolerant galvanizing flux (US Patent 7811389)
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Development Plan
• After first discussions of XNS and Canadian Zn
producer Teck Metals,, a 3-way, 1-year MOU
signed by XNS, Teck and IZA December 2010
• Line designed by Southeast China Univ of
Technology team (G. Kong and RZ Sui),
equipment delivered for first trial August 2011
• 7 trials performed August –September 2011
-Problem of excess dross needed to be
solved
- Coating control needed improvement
(up to 95 µm thickness produced,
wanted 50 µm
- Single strand running at 1 m/min
- The flux worked very well
Zinc…essential for life
The design of the line
First 7 trials August-September
2011
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Xiamen Newsteel Metal Products Co., Ltd
Salt Spray Test
Epoxy resin coated steel Zinc alloy coated steel Z i n c + e p o x y c o m p o s i t e
rebar
rebar
coated rebar
Quantity
Length
Surface finish
3
3
3
25
25
25
Make three man-made diameter defects holes on each side of the rebar, the hole
should penetrate the coating and reach to the steel base, the holes located
between ribs.
Test solution:
Concentration 5% Nacl solution
PH=6.8
Test temperature: 35±
Neutral Salt
Sample placement: Sample and vertical direction at 20 degrees, defect holes
spray test
towards the cabinet side, after 24 hours continuous spray check sample surface
respectively.
Collection volume: ml.
Test result
⒈ Epoxy resin coated steel rebar corroded seriously(rust) at defect hole area
after 24 hours.
⒉ Zinc alloy coated rebar and zinc+epoxy composite coating are corroded after
24 hours.
Zinc…essential for life
Zinc…essential for life
Bending tests on CGR bars at Hong
Kong Poly U. (Prof. Chung and Dr. Ho)
January 2012
• Coating defects noticed on rebar ribs
•  Bending tests carried out with 40mm mandrel
• 135 degree bend showed only small lines of cracks,
judged “good”
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Further developments at
Newsteel - 2013
• 32 mm rebar coating production
• Increase to 3 bars
• Increase to 10 m/min line speed
• Low and high Al coating trials
• Galvanized rebar standard submitted to National
Standardization administration
•  Newsteel and IZA have communicated with
Ministry of Housing and Urban-Rural
Development of China.
Zinc…essential for life
Continuously Galvanized Rebar
(In-Line CGR)
12 mm CGR
Newsteel - 2014
20 Zinc…essential for life
Epoxy coating development: Akzo Nobel
tests May 2013 using CGR from Newsteel
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Akzo Nobel tests May 2013
Test Results
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Zinc…essential for life
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Akzo Nobel tests May 2013
Conclusions
There is no difference when testing the
coated parts directly 1 day after coating or
after 28 days as mentioned by the
customer
Rebar powder sent from USA to Xiamen
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Bend testing of Newsteel CGR by
Gerdau Z-Bar
Satisfactory Result
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USA trademark application
85882085 made by IZA
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Starting of Cooperation with ATI
and Newsteel March 2013
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Case study for continuous
galvanized rebar
•  Project name：
Beijing-Fuzhou
Passenger
Railway Line
Project(JiangxiFujian region)
•  Construction
Company：China
Railway No. 24
Bureau
•  Application Place：
Railway roadbed
cable trough—
Power cable well
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Power Cable Well Reinforcement
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Sample for Highway Substructure
and Building Columns
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Hong Kong Activities
Building Department of HK Government has issued a code
on use of galvanized rebars for building canopies.
An earlier code governed the use of galvanized rebars in
reinforced earth.
1/3 of HK population (2 million people) live in public
housing structures. There is a huge pressure from HK
residents for building far more public housing in the next
10 years
The Housing Department has much interest in galvanized
rebars because of poor experience with unprotected rebar
HK Polytechnic Univ. is performing bend tests, to assist
the drafting of the guideline and specs for CGR.
Zinc…essential for life
Dubai Project
•  First trial by Super
Galvanizing on June
28, 2013, rebar
supplied by Conares
•  Seminar with public
sector customers
November 2013 in
Dubai with Prof.
Yeomans
•  Refinement and
additional trials
continuing
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OneSteel production with
Zn-12%Al
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Other Developments
State DOTs currently banning the use of
fusion bond epoxy rebar (per AZZ
Galvanizing):
Oregon
Virginia
Florida
+ one to be named
New York Thruway System specifies
galvanized coated rebar
ASSHTO has been contacted as is willing to
present any new galvanized rebar
specification to individual states for
consideration
Samples have been sent to interested
producers and users
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Marketing Objectives
-Educate end-users about the problems of
corroding rebar and how these problems are
solved with duplex coated rebar
-Find applications, and their owners, where
corrosion resistant rebar is needed
-Find candidate producers, transfer technology
-Initiate product characterization testing of
duplex rebar versus other protection strategies,
i.e. plain galvanized, epoxy only
-Develop national and public sector standards
permitting use of CGR: ISO 14657 already in
place
Zinc…essential for life
Processing Objectives
•  Newsteel and Super Galvanising
-Adjust process parameters to ensure a
continuous, defect-free galvanized coating
-Produce samples for performance testing
and product characterization.
-Optimize process productivity (line speed,
wiping, pre-treatment)
-On-going production trials in increasing
quantities, sufficient to supply end user
demonstration projects
Replicate with other producers
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Technical Objectives
• Provide firm basis for promulgation of national and
international standards for CGR:
-Establish the lifetime equivalency of the 5060 micron CGR zinc coating and the 137
micron (three ounce) HDG coating in
concrete.
-Establish comparative performance for DCR
vs epoxy-only coated bar and black bar.
-Establish new tighter bend radii
specifications for CGR.
China Rebar Production
2001- 2009 Chi na Rebar Out put
14000
12150
12000
9797
2007
2008
8792
10000
7259
8000
6000
10137
3735
4517
6016
5855
4000
2000
0
2001
2002
2003
2004
2005
2006
2009
District
2009 January-December total rebar
output (ton)
Whole country
121,505,575.91
Beijing
Tianjin
Hebei
Shanxi
Neimenggu
Liaoning
Jilin
Heilongjiang
Shanghai
Jiangsu
Zhejiang
Anhui
Fujian
Jiangxi
Shandong
Henan
Hubei
Hunan
Guangdong
Guangxi
Hainan
Chongqin
Sichuan
Guizhou
Yunnan
Xizang
Shanxi
Gansu
Qinghai
Ningxia
Xinjiang
1,858,598.00
2,640,012.00
13,433,912.00
4,452,147.09
1,274,965.00
4,558,060.72
999,609.70
1,552,057.00
193,949.00
19,011,368.93
1,513,037.74
6,260,963.02
4,109,893.77
5,942,034.50
11,278,926.16
5,162,561.40
2,778,445.04
4,290,993.66
5,089,777.70
3,646,465.79
55,927.00
480,535.38
6,422,355.61
2,186,213.00
3,542,013.00
4,904,124.70
1,504,494.00
88,397.00
342,716.00
1,931,022.00
Zinc…essential for life
Zinc Market Potential
• 200 million tpy rebar
• 10% coated = 20 million
tpy
• With 2% zinc pickup =
400,000 tpy zinc
Zinc…essential for life
www.galvanizedrebar.com

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