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Publication Number: FHWA-HRT-07-039
Date: July 2007

Corrosion Resistant Alloys for Reinforced Concrete

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FOREWORD

Initial cost considerations have historically precluded widespread utilization of high performance (corrosion resistant) reinforcements such as stainless steels in bridge construction. However, with the advent of life-cycle cost analysis as a project planning tool and of a requirement that major bridge structures have a 75- to 100-year design life, the competitiveness of such steels has increased such that enhanced attention has focused in recent years upon these materials.

This investigation was initiated to evaluate the corrosion resistance of various types of corrosion resistant reinforcement, including new products that are becoming available, in bridge structures that are exposed to chlorides. Both long-term (4-year) test yard exposures and accelerated laboratory experiments in simulated concrete pore waters are being performed. The ultimate objective is to, first, evaluate the corrosion properties and rank the different candidate materials and, second, develop tools whereby long-term performance in actual structures can be projected from short-term tests. This interim report presents results from the initial 3 years of an overall 5-year program.

Gary L. Henderson
Director, Office of Infrastructure
Research and Development

Notice

This document is disseminated under the sponsorship of the U. S. Department of Transportation in the interest of information exchange. The U. S. Government and the State of Florida assume no liability for its content or use thereof. This Report does not constitute a standard, specification, or regulation.

The U. S. Government and the State of Florida do not endorse products or manufacturers. Trade and manufacturers’ names appear in this report only because they are considered essential to the objective of this document.

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The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement.

Technical Report Documentation Page

1. Report No.
    FHWA-HRT-07-039

2. Government Accession No.

3. Recipient’s Catalog No.

4. Title and Subtitle
    Corrosion Resistant Alloys for Reinforced Concrete

5. Report Date
    July 2007

6. Performing Organization Code
    FAU-OE-CMM-0601

7.Author(s)
    William H. Hartt,* Rodney G. Powers,** Diane K. Lysogorski,*  Virginie Liroux,* Y. Paul Virmani*** (See Boxes 9 and 12)

8. Performing Organization Report No.
 

9. Performing Organization Name and Address
    *Florida Atlantic University–Sea Tech Campus, 101 North.
    Beach Road, Dania Beach, FL 33004
    **Florida Department of Transportation–State Materials Office,
    5007 NE 39th Street, Gainesville, FL 32609

10. Work Unit No. (TRAIS)

11. Contract or Grant No.
    

12. Sponsoring Agency Name and Address
    ***Office of Infrastructure Research and Development
    Federal Highway Administration
    6300 Georgetown Pike
    McLean, VA 22012

13. Type of Report and Period Covered
    Interim Report

14. Sponsoring Agency Code
    

15. Supplementary Notes
    Contracting Officer’s Technical Representative (COTR): Y.P. Virmani, HRDI-10

16. Abstract
Infrastructure deterioration, which includes corrosion of reinforcing steel in concrete bridges, has been identified as a major economic and societal cost to the United States. For the past 30 years, epoxy-coated reinforcing steel (ECR) has been specified for reinforced concrete bridges exposed to deicing salts and coastal environments. Premature corrosion induced cracking of marine bridge substructures in Florida indicated, however, that ECR is of little benefit for this type of exposure; and while performance of ECR in northern bridge decks has been generally good to-date (30-plus years), still the degree of corrosion resistance to be afforded in the long term to major structures with design lives of 75 to 100 years is uncertain. This concern, combined with increased utilization of life-cycle cost analysis in project planning and materials selection, has caused renewed interest in corrosion resistant reinforcements, stainless steels in particular. The present research study is being performed jointly by Florida Atlantic University and the Florida Department of Transportation to evaluate alloys that have been identified as candidate corrosion resistant reinforcements. These include MMFX-II™ (ASTM A 1035), solid stainless steels 3Cr12 (UNS-S41003), 2201LDX (ASTM A955-98), 2205 (UNS 31803), and two 316L (UNS S31603) alloys; and two 316 stainless steel clad black bar products. Black bar (ASTM A615) reinforcement was included for comparison purposes. Testing methods included three types of short-term exposures: (1) a previously developed method that involves cyclic exposure to synthetic pore solution (SPS) with incrementally increasing chlorides and then to moist air, (2) anodic potentiostatic exposure in SPS with incrementally increasing chlorides, and (3) potentiodynamic polarization scans in saturated Ca(OH)2 at different chloride concentrations. Long-term exposures involve four specimen types: (1) simulated deck slabs, (2) 3-bar columns, (3) macro-cell slab specimens, and (4) field columns. Specimen types (1) and (3) are being cyclically wet-dry ponded with a sodium chloride (NaCl) solution and are intended to simulate northern bridge decks exposed to deicing salts, whereas types (2) and (4) are partially submerged continuously, the former in a NaCl solution and the latter at a coastal marine site in Florida. This report details findings for the initial 3 years of this 5 year project.

17. Key Word
    Reinforced concrete, bridges, corrosion resistance, corrosion testing, high performance reinforcement, stainless steel, MMFX-II™

18. Distribution Statement
    No restrictions. This document is available to the public through the NTIS, Springfield, VA 22161.

19. Security Classif. (of this report)
    Unclassified

20. Security Classif. (of this page)
    Unclassified

21. No. of Pages
    132

22. Price

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized.

Metric Conversion Chart


TABLE OF CONTENTS

 

1. INTRODUCTION

2. PROJECT OBJECTIVES

3. EXPERIMENTAL PROCEDURE
     ACCELERATED SCREENING TESTS
          General
          Materials
          AST-1: Wet-Dry Exposures
            Specimens
            Test Procedure
          AST-2A: Chloride Threshold Determinations
          AST-2B: Pitting Potential Determinations
            Specimens
            Test Procedure
     LONG-TERM TESTS
          Specimen Design
            General
            Simulated Deck Slabs
            Three Bar Columns
            Macro-Cell Slab Specimens
            Field Columns

4. EXPERIMENTAL RESULTS AND DISCUSSION
     SIMULATED PORE WATER PH DATA FOR AST-1 AND AST-2
     AST-1
     AST-2A
     AST-2B
          Open Circuit Potential
          Scan Rate
          Surface Condition:
          Critical Pitting Potential
     CORRELATIONS BETWEEN DIFFERENT SHORT-TERM TEST RESULTS
     RELATING [Clth‾] (AST-2A) TO CHLORIDE THRESHOLD CONCENTRATIONS IN CONCRETE
     CONCRETE SPECIMENS
          General
          Simulated Deck Slab (SDS) Specimens
            General
            Black Bar Slabs
            Slabs Reinforced With MMFX-II™ Bars
            Slabs Reinforced With 3Cr12 Bars
            Slabs Reinforced With 2201 Bars
            Slabs Reinforced With 316 Solid and Clad (Stelax) Stainless Bars
            Chloride Concentration
          Three Bar Columns
            Square Three Bar Column Specimens
            Three Bar Tombstone Columns
          Macro-Cell Slab (MS) Specimens
          Field Columns
          Correlation of Concrete Specimen Data With Results From Accelerated Testing

5. CONCLUSIONS

APPENDIX A
     EXAMPLE PH CALCULATION

APPENDIX B
     EXAMPLE CALCULATION OF CORROSION RATE FROM POLARIZATION RESISTANCE

APPENDIX C
     EXAMPLE CALCULATION OF CORROSION RATE FROM WEIGHT LOSS DATA

BIBLIOGRAPHY


LIST OF FIGURES

Figure 1.1. Photo. Cracked and spalled marine bridge piling

Figure 1.2. Schematic illustration. Various steps in deterioration of reinforced concrete due to chloride induced corrosion

Figure 3.1. Photo. Straight, as-received, MMFX-II™ bar with epoxy-mounted ends and electrical lead

Figure 3.2. Photo. Three bent, as-received Type 2201 stainless steel bars with electrical leads

Figure 3.3. Photo. Abraded MMFX-II™ specimen

Figure 3.4. Photo. Damaged MMFX-II™ specimen

Figure 3.5. Photo. AST-1 wet-dry exposure setup.

Figure 3.6. Photo. AST-1 specimens under test in the upper hold tank (figure 3.5)

Figure 3.7. Schematic illustration. AST-2A experimentation

Figure 3.8. Photo. AST-2A test system

Figure 3.9. Photo. Test chamber with specimens

Figure 3.10. Illustration and photo. Schematic illustration (a) and photograph (b) of the as-received, circumferential AST-2B test specimen

Figure 3.11. Photo. Polished circumferential specimen

Figure 3.12. Schematic illustration. Polished cross section surface specimen

Figure 3.13. Photo. Two polished cross section specimens

Figure 3.14. Photo. Test cell for potentiodynamic polarization measurements

Figure 3.15. Schematic illustration. Standard simulated deck slab specimens

Figure 3.16. Schematic illustration. CREV type simulated deck slab specimens

Figure 3.17. Graphic. Standard specimen nomenclature

Figure 3.18. Graphic. Nonstandard specimen nomenclature

Figure 3.19. Photo. Ponded deck slab specimen under test

Figure 3.20. Photo. Perspective view of exposure site and specimens

Figure 3.21. Schematic illustration. Square three bar column specimen for each of the three bar configurations

Figure 3.22. Schematic illustration. Tombstone type three bar column specimen for each of the three bar configurations

Figure 3.23. Photo. Three bar column specimens under exposure

Figure 3.24. Schematic illustration. Geometry of the macro-cell slab type specimen with both bent and straight bars

Figure 3.25. Photo. Macro-cell slab specimens under exposure

Figure 3.26. Schematic illustration. Geometry of the field column type specimen

Figure 3.27. Photo. Field column specimens under exposure at the Intracoastal Waterway site in Crescent Beach, FL

Figure 4.1. Graph. Change in pH and [Cl-] as a function of time for AST-1 and AST-2 experiments

Figure 4.2. Graph. Plot of polarization resistance versus exposure time for representative alloys during different AST-1 runs (numbers in parentheses)

Figure 4.3. Graph. Plot of polarization resistance versus exposure time for intermediate performing alloys and black bars during different AST-1 (number in parentheses after each alloy designation indicates different AST-1 runs

Figure 4.4. Graph. Plot of polarization resistance versus exposure time for 2201 stainless steel AST-1 specimens with different surface preparation conditions

Figure 4.5. Graph. Plot of polarization resistance versus exposure time for clad stainless steel AST-1 specimens

Figure 4.6. Graph. Plot of polarization resistance versus exposure time for clad stainless steel AST-1 specimens in the intact, abraded (A), and damaged (D) conditions

Figure 4.7. Graph. Plot of polarization resistance for straight versus bent solid bars

Figure 4.8. Graph. Plot of polarization resistance for straight versus bent clad bars

FFigure 4.9. Graph. Comparison of corrosion rate measured by weight loss and calculated from polarization resistance for different solid bars

Figure 4.10. Photo. Type 316 SS specimens subsequent to AST-1 testing

Figure 4.11. Photo. Type 2205 SS specimens subsequent to AST-1 testing

Figure 4.12. Photo. Type 2201 SS specimens subsequent to AST-1 testing

Figure 4.13. Photo. MMFX-II™ specimens subsequent to AST-1 testing

Figure 4.14. Photo. MMFX-II™ abraded specimens subsequent to AST-1 testing

Figure 4.15. Photo. MMFX-II™ damaged specimens subsequent to AST-1 testing

Figure 4.16. Photo. Black bar specimens subsequent to AST-1 testing

Figure 4.17. Graph. Plot of current density versus [Cl‾] such that [Clth‾ ] for alloys with intermediate corrosion resistance is revealed (specimens with B in the designation were bent)

Figure 4.18. Graph. Plot of current density versus [Cl‾] such that [Clth‾ ] for alloys with relatively high corrosion resistance is revealed

Figure 4.19. Graph. Expanded scale plot of current density versus [Cl‾] for alloys with relatively high corrosion resistance is revealed

Figure 4.20. Graph. Plot of current density versus exposure time for 10 specimens each of
black bar and 3Cr12. Incremental Cl‾ additions are also shown

Figure 4.21. Graph. Expanded scale view of the current density versus exposure time data from figure 4.20

Figure 4.22. Graph. Plot of current density versus time for a series of 10 MMFX and 2201 specimens polarized to +100 mVSCE. Incremental Cl‾ additions are also shown

Figure 4.23. Graph. Plot of current density versus time for replicate MMFX-II™ specimens

Figure 4.24. Graph. Distribution of [Clth‾ ] for four alloys based upon the 10 µA/cm² current density criterion

Figure 4.25. Graph. Anodic CPP scans for as-received MMFX-II™ specimens in saturated Ca(OH)2 without Cl‾ at scan rates of 0.33, 1.00, and 5.00 mV/s. Arrows indicate direction of forward and reverse scans

Figure 4.26. Graph. Anodic CPP scans on as-received MMFX-II™ specimens with three surface conditions in saturated Ca(OH)2 without Cl‾ at 1.00 mV/s. Arrows indicate direction of forward and reverse scans

Figure 4.27. Graph. Critical pitting potential as a function of [Cl‾] for four bar types

Figure 4.28. Graph. Plot of polarization resistance (AST-1) versus PREN for the test reinforcements

Figure 4.29. Graph. Plot of polarization resistance (AST-1) versus [Clth‾ ] (AST-2A)

Figure 4.30. Graph. Plot of [Clth‾ ] (AST-2A) versus PREN

Figure 4.31. Graph. Plot of [Clth‾ ] (AST-2A) versus the corresponding threshold projected from literature data for pastes, mortars, and concrete

Figure 4.32. Graph. Plot of potential versus exposure time for STD1 and STD2 concrete specimens with black bar reinforcement

Figure 4.33. Graph. Plot of macro-cell current density versus exposure time for STD1 and STD2 concrete specimens with black bar reinforcement

Figure 4.34. Graph. Plot of potential versus exposure time for black bar STD1 concrete specimens with and without a simulated crack

Figure 4.35. Graph. Plot of macro-cell current density versus exposure time for black bar STD1 concrete specimens with and without a simulated crack

Figure 4.36. Graph. Plot of potential versus macro-cell current density for black bar reinforced concrete specimens

Figure 4.37. Photo. Exposed surface of specimen number 3-CCON-BB-2 after 377 days

Figure 4.38. Photo. Traces of the upper three rebars and heavy corrosion products (specimen number 3-CCON-BB-1)

Figure 4.39. Photo. Trace of the upper rebars and heavy corrosion products on specimen number 1-STD1-BB-3

Figure 4.40. Graph. Plot of potential versus exposure time for STD1 concrete specimens with MMFX-II™ reinforcement in comparison to black bar results

Figure 4.41. Graph. Plot of macro-cell current density versus exposure time for STD1 concrete specimens with MMFX-II™ reinforcement in comparison to black bar results

Figure 4.42. Graph. Plot of potential versus exposure time for STD1 and STD2 concrete specimens with MMFX-II™ reinforcement

Figure 4.43. Graph. Plot of macro-cell current density versus exposure time for STD1 and STD2 concrete specimens with MMFX-II™ reinforcement

Figure 4.44. Graph. Plot of potential versus exposure time for STD1 concrete specimens with black bar bottom mat and top mat MMFX-II™ reinforcement compared to ones with all MMFX-II™ bars

Figure 4.45. Graph. Plot of macro-cell current density versus exposure time for STD1 concrete specimens with black bar bottom mat and top mat MMFX-II™ reinforcement compared to ones with all MMFX-II™ bars

Figure 4.46. Graph. Plot of potential versus exposure time for STD1 concrete specimens with as-received and wire brushed (WB) MMFX-II™ reinforcement

Figure 4.47. Graph. Plot of macro-cell current density versus exposure time for STD1 concrete specimens with as-received and wire brushed (WB) MMFX-II™ reinforcement

Figure 4.48. Graph. Plot of potential versus exposure time for STD1 concrete specimens with top mat crevice bars (splice) and MMFX-II™ reinforcement compared to ones with normal bar placement

Figure 4.49. Graph. Plot of macro-cell current density versus exposure time for STD1 concrete specimens with top mat crevice bars (splice) and MMFX-II™ reinforcement

Figure 4.50. Graph. Plot of potential versus exposure time for STD1 concrete specimens with a simulated concrete crack and MMFX-II™ reinforcement compared to normal (uncracked) specimens

Figure 4.51. Graph. Plot of macro-cell current density versus exposure time for STD1 concrete specimens with a simulated concrete crack and MMFX-II™ reinforcement compared to normal (uncracked) specimens

Figure 4.52. Graph. Plot of potential versus exposure time for STD1 concrete specimens with a simulated concrete crack and MMFX-II™ reinforcement compared to ones with a simulated crack and top bar crevice (splice)

Figure 4.53. Graph. Plot of macro-cell current density versus exposure time for STD1 concrete specimens with a simulated concrete crack and MMFX-II™ reinforcement compared to ones with a simulated crack and top bar crevice (splice)

Figure 4.54. Graph. Plot of potential versus exposure time for STD1 concrete specimens with a simulated concrete crack and MMFX-II™ reinforcement compared to ones with a simulated crack and black bottom bars

Figure 4.55. Graph. Plot of macro-cell current density versus exposure time for STD1 concrete specimens with a simulated concrete crack and MMFX-II™ reinforcement compared to ones with a simulated crack and black bar bottom mat

Figure 4.56. Graph. Plot of potential versus macro-cell current density for MMFX-II™ reinforced specimens

Figure 4.57. Photo. Top surface of specimen 2-BCAT-MMFX-3 after 461 days of exposure

Figure 4.58. Photo. Trace of the upper rebars and corrosion products on specimen number 1-STD1-MMFX-2

Figure 4.59. Photo. Trace of the upper rebars and corrosion products on specimen number 1-STD2-MMFX-2

Figure 4.60. Photo. Trace of the upper rebars and corrosion products on specimen number 2-WB-MMFX-1

Figure 4.61. Photo. Trace of the upper rebars and corrosion products on specimen number 3-CREV-MMFX-1

Figure 4.62. Photo. Trace of the upper rebars and corrosion products on specimen number 1-CCON-MMFX-1

Figure 4.63. Photo. Trace of the upper rebars and corrosion products on specimen number 2-BCAT-MMFX-1

Figure 4.64. Photo. Trace of the upper rebars and corrosion products on specimen number 2-CCNB-MMFX-1

Figure 4.65. Photo. Trace of the upper rebars and corrosion products on specimen number 3-CCRV-MMFX-1

Figure 4.66. Graph. Plot of potential versus exposure time for STD1 concrete specimens with 3Cr12 reinforcement compared to that for black bar

Figure 4.67. Graph. Plot of macro-cell current density versus exposure time for STD1 concrete specimens with 3Cr12 reinforcement compared to that for black bar

Figure 4.68. Graph. Plot of potential versus exposure time for STD1 and STD2 concrete specimens with 3Cr12 reinforcement

Figure 4.69. Graph. Plot of macro-cell current density versus exposure time for STD1 and STD2 concrete specimens with 3Cr12 reinforcement.

Figure 4.70. Graph. Plot of potential versus exposure time for STD1 concrete specimens with wire brushed compared to as-received 3Cr12 bars

Figure 4.71. Graph. Plot of macro-cell current density versus exposure time for STD1 concrete specimens with wire brushed compared to as-received 3Cr12 bars

Figure 4.72. Graph. Plot of potential versus exposure time for STD1 concrete specimens with top mat bar crevice (splice) and 3Cr12 reinforcement compared to ones with normal bar placement

Figure 4.73. Graph. Plot of macro-cell current density versus exposure time for STD1 concrete specimens with top mat bar crevice (splice) and 3Cr12 reinforcement compared to ones with normal bar placement

Figure 4.74. Graph. Plot of potential versus exposure time for STD1 concrete specimens with a simulated concrete crack and 3Cr12 reinforcement compared to uncracked ones

Figure 4.75. Graph. Plot of macro-cell current density versus exposure time for STD1 concrete specimens with a simulated concrete crack and 3Cr12 reinforcement compared to uncracked ones

Figure 4.76. Graph. Plot of potential versus exposure time for STD1 concrete specimens with black bar bottom mat and top mat 3Cr12 reinforcement compared to ones with all 3Cr12 bars

Figure 4.77. Graph. Plot of macro-cell current density versus exposure time for STD1 concrete specimens with black bar bottom mat and top mat 3Cr12 reinforcement compared to ones with all 3Cr12 bars

Figure 4.78. Graph. Plot of potential versus exposure time for STD1 concrete specimens with a simulated concrete crack and 3Cr12 reinforcement compared to cracked ones with a simulated crack and top bar crevice (splice)

Figure 4.79. Graph. Plot of macro-cell current density versus exposure time for STD1 concrete specimens with a simulated concrete crack and 3Cr12 reinforcement compared to cracked ones with a simulated crack and top bar crevice (splice)

Figure 4.80. Graph. Plot of potential versus macro-cell current density for 3Cr12 reinforced specimens

Figure 4.81. Photo. Trace of the upper rebars and corrosion products on specimen number 1-STD1-3Cr12-1

Figure 4.82. Photo. Trace of the upper rebars and corrosion products on specimen number 1-STD2-3Cr12-1

Figure 4.83. Photo. Trace of the upper rebars and corrosion products on specimen number 1-WB-3Cr12-1

Figure 4.84. Photo. Trace of the upper rebars and corrosion products on specimen number 1-CREV-3Cr12-1

Figure 4.85. Photo. Trace of the upper rebars and corrosion products on specimen number 1-CCON-3Cr12-1

Figure 4.86. Photo. Trace of the upper rebars and corrosion products on specimen number 1-BCAT-3Cr12-1

Figure 4.87. Photo. Trace of the upper rebars and corrosion products on specimen number 1-CCRV-3Cr12-1.

Figure 4.88. Graph. Plot of potential versus exposure time for STD1 concrete specimens with 2201 reinforcement compared to data for black bar

Figure 4.89. Graph. Plot of macro-cell current density versus exposure time for STD1 concrete specimens with 2201 reinforcement compared to data for black bar

Figure 4.90. Graph. Plot of potential versus exposure time for STD1 and STD2 concrete specimens with 2201 reinforcement

Figure 4.91. Graph. Plot of macro-cell current density versus exposure time for STD1 and STD2 concrete specimens with 2201 reinforcement

Figure 4.92. Graph. Plot of potential versus exposure time for STD1 concrete specimens with wire brushed (WB) 2201 bars compared to ones with as-received 2201 bars

Figure 4.93. Graph. Plot of macro-cell current density versus exposure time for STD1 concrete specimens with wire brushed (WB) 2201 bars compared to ones with as-received 2201 bars

Figure 4.94. Graph. Plot of potential versus exposure time for STD1 concrete specimens with top mat crevice bars (splice) and 2201 reinforcement compared to ones with normal bar placement

Figure 4.95. Graph. Plot of macro-cell current density versus exposure time for STD1 concrete specimens with top mat crevice bars (splice) and 2201 reinforcement compared to ones with normal bar placement

Figure 4.96. Graph. Plot of potential versus exposure time for STD1 concrete specimens with a simulated crack and 2201 reinforcement compared to uncracked ones

Figure 4.97. Graph. Plot of potential versus exposure time for STD1 concrete specimens with a simulated crack and 2201 reinforcement compared to uncracked ones

Figure 4.98. Graph. Plot of potential versus exposure time for STD1 concrete specimens with top mat 2201 bars and bottom mat black bar compared to ones with all 2201 bars

Figure 4.99. Graph. Plot of macro-cell current density versus exposure time for STD1 concrete specimens with top mat 2201 bars and bottom mat black bar compared to ones with all 2201 bars

Figure 4.100. Graph. Plot of potential versus exposure time for STD1 concrete specimens with a simulated concrete crack and 2201 reinforcement compared to ones with a simulated crack and black bottom bars

Figure 4.101. Graph. Plot of macro-cell current density versus exposure time for STD1 concrete specimens with a simulated concrete crack and 2201 reinforcement compared to ones with a simulated crack and black bottom bars

Figure 4.102. Graph. Plot of potential versus exposure time for STD1 concrete specimens with a simulated crack and crevice at top bars (splice) and 2201 reinforcement compared results for ones with cracked concrete and normal top bar placement

Figure 4.103. Graph. Plot of macro-cell current density versus exposure time for STD1 concrete specimens with a simulated crack and crevice at top bars (splice) and 2201 reinforcement compared results for ones with cracked concrete and normal top bar placement

Figure 4.104. Graph. Plot of potential versus macro-cell current density for 2201 reinforced specimens

Figure 4.105. Photo. Trace of the upper rebars and corrosion products on specimen number 1-STD1-2201-3

Figure 4.106. Photo. Trace of the upper rebars and corrosion products on specimen number 1-STD1-2202-2

Figure 4.107. Photo. Trace of the upper rebars and corrosion products on specimen number 1-WB-2201-1

Figure 4.108. Photo. Trace of the upper rebars and corrosion products on specimen number 1-CREV-2201-1

Figure 4.109. Photo. Trace of the upper rebars and corrosion products on specimen number 1-CCON-2201-1

Figure 4.110. Photo. Trace of the upper rebars and corrosion products on specimen number 1-BCAT-2201-1

Figure 4.111. Photo. Trace of the upper rebars and corrosion products on specimen number 1-CCNB-2201-1

Figure 4.112. Photo. Trace of the upper rebars and corrosion products on specimen number 1-CCRV-2201-1

Figure 4.113. Graph. Plot of average potential versus average macro-cell current density at each measurement time for three specimens of the four indicated

Figure 4.114. Graph. Plot of potential versus exposure time for STD1 and STD2 concrete specimens with 316.18, 316.17, and Stelax reinforcement compared to that for black bar in STD1 concrete

Figure 4.115. Graph. Plot of macro-cell current density versus exposure time for STD1 and STD2 concrete specimens with 316.18 reinforcement compared to ones with black bar in STD1 concrete

Figure 4.116. Graph. Plot of chloride concentration at 2.54 cm below the exposed surface of STD1 concrete slabs versus exposure time

Figure 4.117. Graph. Time-to-corrosion results for square 3-bar column specimens

Figure 4.118. Graph. Example potential and current data for macro-cell slab specimens

Figure 4.119. Graph. Time-to-corrosion results for the macro-cell slab specimens without a simulated crack

Figure 4.120. Graph. Time-to-corrosion results for the macro-cell slab specimens with a simulated crack

Figure 4.121. Graph. Plot of time-to-corrosion of reinforced concrete specimens as a function of [Clth‾] as determined from accelerated testing

Figure 4.122. Photo. Example of corner cracking on a 2201 reinforced simulated deck slab specimen

Figure 4.123. Graph. Chloride profile from each of two cores taken from STD1 concrete slabs after 136 days of exposure

LIST OF TABLES

Table 3.1. Listing of reinforcing steel types

Table 3.2. Chemical composition of the rebar types

Table 3.3. Listing of AST-1 runs and the rebar and specimen type for each (“x” indicates that the indicated alloy was tested during that run, and “2” indicates two sets of triplicate specimens)

Table 3.4. Listing of each AST-2A run according to rebar type and number of specimens

Table 3.5. Listing of the number of AST-2B tests for each specimen type and surface condition

Table 3.6. Concrete mix designs

Table 3.7. Listing of the various specimen types, variables, and nomenclature for each

Table 3.8. Listing of specimens reinforced with 316.18 and 3Cr12

Table 3.9. Listing of specimens with 2201 rebar (specimens in shaded cells not yet fabricated)

Table 3.10. Listing of specimens reinforced with MMFX-II™

Table 3.11. Listing of specimens reinforced with Stelax (specimens in shaded cells not yet fabricated)

Table 3.12. Listing of specimens reinforced with SMI (specimens in shaded cells not yet fabricated)

Table 3.13. Listing of specimens reinforced with black bar

Table 4.1. Average polarization resistance for each alloy during each 28-day period of six individual AST-1 runs

Table 4.2. Polarization resistance for each alloy averaged over the six individual AST-1 runs

Table 4.3. Corrosion rate calculated from weight loss of individual specimens of each alloy at the end of the indicated NaCl exposure for the indicated run

Table 4.4. Average corrosion rate calculated from weight loss for each alloy during four individual AST-1 runs

Table 4.5. Listing of projected CT values for the corresponding [Clth‾ ] from AST-2A

Table 4.6. Calculated times-to-corrosion for concrete specimens

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