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89 Pages·2010·1.94 MB·English

Sustainable Development, Global Change and Ecosystems
Sustainable Surface Transport

Strategic Targeted Research Project
ARCHES
Assessment and Rehabilitation of Central European Highway Structures
Recommendations for the use of corrosion resistant reinforcement

Deliverable D11
Document number: ARCHES-03-DE11 Date: 25.08.2009
Name and signature Date
Aljoša Šajna, Andraž Legat, Dubravka
Bjegović, Tadeja Kosec, Irina Stipanović
Drafted: 25.07.2009
Oslaković, Marijana Serdar, Viljem Kuhar, Nina
Gartner, Livia Pardi, Lukasz Augustynski
Reviewed: Mirjam Leban, Agnieszka Krolikowska 20.08.2009
Prof. Bernhard Elsener 25.08.2009

Approved by ARCHES Management Group:

Tomasz Wierzbicki
Foreword
Activities concerning evaluation, repair and restoration of concrete structures are estimated as
35 % of all the work in the building sector. The main reason for degradation of reinforced
concrete structures is the corrosion of steel reinforcement. One of the possible solutions for
tackling this problem successfully is the use of stainless steel reinforcement.
The use of suitable reinforcing steel should provide a cost-effective solution for corrosion
protection on road infrastructure in specific environments. Unfortunately, the use of stainless
steel in reinforced concrete structures in many cases represents unaffordable additional costs. For
this reason, the research presented herein included low-priced corrosion resistant reinforcing
steels with lower content of alloying elements. Six different types of corrosion resistant
reinforcement available on the market were investigated and compared. Black steel was included
in the tests as comparison reference.
This document was prepared to provide engineers with practical guidance for the use of different
types of reinforcing steel, such as stainless steel and especially corrosion resistant reinforcing steel
with lower content of alloying elements. The main purpose of the recommendations herein is to
provide users with relevant information as to when and where a specific type of steel
reinforcement should be used.
These guidelines were prepared on the basis of a laboratory investigation of corrosion properties
of different corrosion resistant steels in specific aggressive conditions, such as chloride
contaminated and/or carbonated concrete. The document does not include the corrosion
behaviour of tested steel reinforcement at extreme conditions, such as high temperature, dynamic
or impact loading.
These Guidelines are a result of three-year ARCHES research project. Only selected results are
presented in this document.
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TABLE OF CONTENTS
LIST OF FIGURES................................................................................................................III
LIST OF TABLES..................................................................................................................IV
1. EXECUTIVE SUMMARY................................................................................................1
1. 1 Goals and objectives....................................................................................................1
2. DURABILITY OF REINFORCED CONCRETE STRUCTURES...............................3
2. 1 General background.....................................................................................................3
2. 2 Mechanism of steel corrosion in concrete...................................................................7
2.2.1 Carbonation induced corrosion.................................................................................................8
2.2.2 Chloride induced corrosion.......................................................................................................9
2. 3 Engineering properties of reinforcing steel...............................................................12
2.3.1 Introduction..............................................................................................................................12
2.3.2 Black reinforcing steels............................................................................................................13
2.3.3 Corrosion resistant steels........................................................................................................14
2.3.4 Physical and mechanical properties of reinforcing steels...................................................27
3. CORROSION TESTING...............................................................................................30
3. 1 Corrosion monitoring ................................................................................................30
3.1.1 Open-circuit potential (OCP) measurements.......................................................................30
3.1.2 Polarization resistance measurement.....................................................................................30
3.1.3 Galvanostatic pulse technique................................................................................................30
3.1.4 Electrical resistance probes (ER)...........................................................................................31
3.1.5 Macro-cell current technique..................................................................................................31
3.1.6 Electrochemical noise (EN)....................................................................................................31
3. 2 Measuring techniques................................................................................................32
3.2.1 Corrosion potential..................................................................................................................32
3.2.2 Electrochemical impedance spectroscopy (EIS).................................................................33
3.2.3 Potentiodynamic measurements............................................................................................34
3.2.4 ER probes..................................................................................................................................36
3. 3 Experimental programme..........................................................................................36
3.3.1 Introduction..............................................................................................................................36
3.3.2 Steel used for testing................................................................................................................37
3.3.3 Testing in pore solution...........................................................................................................41
3.3.4 Concrete specimens.................................................................................................................43
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3.3.5 ER probes in concrete specimens..........................................................................................44
3. 4 Summary of test results..............................................................................................45
4. LIFE CYCLE COSTING, COST ASPECTS..................................................................51
4. 1 Introduction...............................................................................................................51
4. 2 Life cycle of concrete structures................................................................................51
4. 3 Analysis (LCCA) ........................................................................................................52
4. 4 LCC calculation procedure........................................................................................53
4. 5 Costs and returns included in LCC analysis..............................................................53
4. 6 Case study 1: Krk bridge............................................................................................54
4. 7 Case study 2: Repair works on highway overpasses..................................................58
4. 8 Conclusion.................................................................................................................61
5. GUIDELINES FOR THE SELECTION OF REINFORCING STEEL.....................62
5. 1 Introduction...............................................................................................................62
5. 2 Tailored selection of steel reinforcement based on corrosion resistance..................62
5. 3 General rules for designing concrete structures with corrosion resistant steel
reinforcement.............................................................................................................65
5.3.1 Designing concrete section......................................................................................................65
5.3.2 Transportation, inspection and acceptance on site..............................................................67
5.3.3 Considerations during installation (welding, cutting, bending, placement)......................69
5. 4 Life cycle aspects of steel selection...........................................................................70
REFERENCES........................................................................................................................71

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LIST OF FIGURES
Figure 1 Degradation of reinforced concrete structures due to corrosion: a)
Maslenica bridge, Croatia; b) Torpedo structure, Rijeka, Croatia; c) Bridge
in the suburbs of Ljubljana, Slovenia......................................................................................3
Figure 2 Share of corrosion costs in the US according to FHWA research [4]................................4
Figure 3 Different levels of durability design [7]...................................................................................4
Figure 4 a) Growth of corrosion products; b) Cracking of concrete cover......................................8
Figure 5 a) Dependence of carbonation on relative humidity; b) Concrete
specimens after spraying with phenolphthalein....................................................................9
Figure 6 Degradation of a reinforced concrete structure due to: a) exposure of
structures to chlorides in a marine atmosphere zone; b) de-icing salts.............................9
Figure 7 Pitting corrosion of steel in concrete....................................................................................10
Figure 8 Critical chloride content according to CEB recommendations [10].................................11
Figure 9: General types of reinforcing steels........................................................................................13
Figure 10 Schaeffler diagram [22]............................................................................................................16
Figure 11 SEM photography of corrosion products on low alloy steel, type “a-la Cor-
ten” (containing 0.8 % Cr, 0.6 % Ni and 0.4 % Cu); a) cross section b)
surface corrosion products [35].............................................................................................17
Figure 12 Nyquist and Bode presentation of data fitted with Randless Circuit...............................33
Figure 13 Potentiodynamic curve............................................................................................................35
Figure 14 Presentation of anodic polarization curve............................................................................35
Figure 15 Sigma/Epsilon diagram...........................................................................................................41
Figure 16 Electrodes for accelerated corrosion testing on cross section...........................................42
Figure 17 Electrodes for accelerated corrosion testing on external surface......................................42
Figure 18 Heavily corroded external surface of specimen TOP12 (1.4003) after
performing potentiodynamic polarisation in highly basic environment up
to potential of 1.5 V................................................................................................................43
Figure 19 a) ER probes made of the black steel and b) stainless steel in concrete
specimens before concreting (ZAG)....................................................................................45
Figure 20 Life cycle of a concrete structure...........................................................................................52
Figure 21 a) View of the island of Krk from the mainland, b) Cracking due to
corrosion on column, and c) lower part of the Big arch...................................................55
Figure 22 Life cycle costs for Krk bridge...............................................................................................57
Figure 23 Degradation processes on main structural elements of the overpass...............................58
Figure 24 LCCA for different repair alternatives for highway bridge................................................61
Figure 25 Different markings of steel.....................................................................................................68
Figure 26 a) Acceptable surface condition (2 bars on the top) and unacceptable
surface condition of the stainless steel rebars (bar at the bottom) with
rolled-in-mill scale and/or not adequately pickled surface and mechanical
damages, rust; b) Ferritic stainless steel rebars with darker colour surface
or even with rolled-in-mill scale and/or not adequately pickled surface are
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unacceptable; c) Surface corrosion on the stainless steel bars, caused by
contamination of steel surface by black steel and iron......................................................68
LIST OF TABLES
Table 1 Classification of environment with rules for concrete mix design.....................................6
Table 2 Maximum chloride content in concrete [8]..........................................................................12
Table 3 Mechanical properties of steel reinforcement.....................................................................14
Table 4 Chemical composition of reinforcing bars in wt. % 1).......................................................14
Table 5 Effect of alloying elements on the anti-corrosion properties of low alloy
steel in marine environments [21].........................................................................................18
Table 6 Pitting resistance equivalent numbers (PREN) for different stainless steels
[68].............................................................................................................................................27
Table 7 Physical properties of different types of steel [70][71][72]................................................28
Table 8 Physical properties of different types of stainless steel [73]..............................................28
Table 9 Mechanical properties of different types of reinforcing steel...........................................28
Table 10 Detailed list of performed testing during project...............................................................37
Table 11 Types of steel tested in the ARCHES project.....................................................................38
Table 12 Chemical composition of chosen steel grades according standard EN
10088-1 (or standard EN 1922-1.1 in case of B500B) and results of
chemical analysis performed for the purpose of the ARCHES research........................39
Table 13 Chromium and Nickel equivalents of tested steel types....................................................40
Table 14 Mechanical properties of tested steel types.........................................................................40
Table 15 Different concrete specimens tested in ARCHES project...............................................44
Table 16 Chemical composition of the AISI 304 (1.4301) grade stainless steel for
ER probes.................................................................................................................................44
Table 17 Mechanical properties of the AISI 304 (1.4301) grade stainless steel for
ER probes.................................................................................................................................45
Table 18 Qualitative estimation deduced from anodic polarization measurements
for the different tested steels in pore solution pH 12.4 and ph 10.1 (Table
25 and Table 26 in Appendix A)...........................................................................................46
Table 19 Qualitative estimation deduced from electrochemical impedance
spectroscopy results for all tested steel specimen at two different pH of
pore solution with different additions of chloride ions(Table 27 in
Appendix A).............................................................................................................................47
Table 20 Concrete specimens with embedded ER probes rebars: mean values of
corrosion potentials of the steel rebars vs. time (Cu-CuSO half-cell)............................49
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Table 21 Concrete specimens with artificial transverse cracks: corrosion potentials
of the steel rebars vs. time (Cu-CuSO half-cell)................................................................49
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Table 22 Overview of repair and maintenance works on Krk bridge..............................................56
Table 23 Cost calculations for selective use of stainless steel...........................................................57
Table 24 List of repair works on deck slab, abutments and columns for all 3
alternatives................................................................................................................................59
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Table 25 Recommendation for the use of corrosion resistant reinforcement with
respect to the exposure classes – selection of suitable stainless steel grades
for different exposure conditions (see Table 11) [67][69]..................................................63
Table 26 Recommendation for the use of corrosion resistant reinforcement with
respect to the chloride content and concrete carbonation................................................64
Table 27 Price ratio for different corrosion resistant steel types in comparison with
ordinary black steel..................................................................................................................65
Table 28 Maximum allowed crack widths............................................................................................67

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