9076-DG - Addendum No. 1.pdf

FLORIDA DEPARTMENT OF TRANSPORTATION

Procurement Office

605 Suwannee Street, MS 20 Tallahassee, Florida 32399-0450

Phone: (850) 414-4253

ADDENDUM NO. 1 DATE: March 14, 2024

BID No.: DOT-RFP-24-9076-DG

BID Title: Durability and Effectiveness Analysis of Solar and Wind-Powered Cathodic Protection Systems

OPENING DATE: Wednesday, April 3, 2024 @ 9:00 AM EST

Notice is hereby given of the following changes to the above-referenced SOLICITATION:

The “Evaluation of FDOT Corrosion Prevention and Control Programs BE725 Final Reports” as mentioned within Exhibit A-Scope of Services, was left out of the solicitation advertisement. It is attached below and is hereby made a part of this solicitation and the resulting contract.

Bidders/Proposers must acknowledge receipt of this Questions and Answers Document by completing and returning to the Procurement Office, by no later than the time and date of the bid/proposal opening. Failure to do so may subject the bidder/proposer to disqualification.

Destyne Grayson, Procurement Agent

Bidder/Proposer

Address

Submitted by (Signature)

Failure to file a protest within the time prescribed in Section 120.57(3), Florida Statutes, or failure to post the bond or other security required by law within the time allowed for filing a bond shall constitute a waiver of proceedings under Chapter 120, Florida Statutes.

Evaluation of FDOT Corrosion Prevention and Control

Programs

DOT-RFP-19-9059-GH

Tallahassee, Florida

FINAL REPORT

May 20, 2022

WJE No. 2019.0352.0

PREPARED FOR:

Mr. Shannon Deese

Florida Department of Transportation

605 Suwannee Street, Mail Station 20

Tallahassee, Florida 32399-0450

PREPARED BY:

Wiss, Janney, Elstner Associates, Inc.

110 East Broward Boulevard, Suite 1860

Fort Lauderdale, Florida 33301

Evaluation of FDOT Corrosion Prevention and Control

Programs

Tallahassee, Florida

FINAL REPORT

May 20, 2022

WJE No. 2019.0352.0

PREPARED FOR:

Mr. Shannon Deese

Florida Department of Transportation

605 Suwannee Street, Mail Station 20

Tallahassee, Florida 32399-0450

PREPARED BY:

Evaluation of FDOT Corrosion Prevention and Control Programs

FINAL REPORT | WJE No. 2019.0352.0 | MAY 20, 2022

DISCLAIMER

The opinions, findings, and conclusions expressed in this publication are those of the authors and not necessarily those of the Florida Department of Transportation.

FINAL REPORT | WJE No. 2019.0352.0 | MAY 20, 2022

1. Report No.

2. Government Accession No.

3. Recipient's Catalog No.

4. Title and Subtitle

Evaluation of FDOT Corrosion and Control Programs

5. Report Date

May 2022

6. Performing Organization Code

7. Author(s)

Matthew Fadden, PhD, Casey Jones, John Lawler, PhD, Crisol Ortiz, Marwa

Abdelrahman, PhD, Wiss, Janney, Elstner Associates, Inc.

Kingsley Lau, PhD, Samanbar Permeh, Florida International University

8. Performing Organization Report No.

9. Performing Organization Name and Address

Wiss, Janney, Elstner Associates, Inc.

110 East Broward Boulevard, Suite 1860

Fort Lauderdale, Florida 33301

10. Work Unit No. (TRAIS)

11. Contract or Grant No.

BE725

12. Sponsoring Agency Name and Address

Florida Department of Transportation

605 Suwannee Street, Mail Station 20

Tallahassee, Florida 32399

13. Type of Report and Period Covered

Final Report, 03/25/2019 through 05/31/2022

14. Sponsoring Agency Code

15. Supplementary Notes

16. Abstract

Corrosion of Florida’s bridge infrastructure has shown to be costly for FDOT, both due to the number of bridges and harsh environmental conditions across the State. While the mechanisms that describe corrosion within reinforced concrete bridge elements are well understood, the ability to limit corrosion in practice has led to many methods that aim to mitigate the effects of corrosion. These systems include durability-based design requirements for new bridges and rehabilitation efforts for existing bridges, summarized in this report. FDOT has implemented many of these systems on its bridges with varying degrees of success.

This report also summarizes current FDOT design requirements and specifications regarding corrosion control for reinforced concrete bridge structures with a focus on substructure elements.

A comprehensive study that compares multiple practices and systems across various Florida bridges has been undertaken. As a result, comparative data related to their performances have been compiled and analyzed. Without this information, it is challenging for the State to understand the benefits of its corrosion control measures and the life-cycle cost analysis of the systems. Therefore, this study aims to evaluate and compare multiple practices and systems used across the State in terms of durability, cost, and long-term performance. Although every corrosion prevention and control program described in this report will not be incorporated into this research, this study includes the most used measures, including concrete cover, supplementary cementitious materials, epoxy coating, and cathodic protection (metalized, impressed current, and galvanic).

17. Key Word

Corrosion, bridge, cathodic protection, durability, cost

18. Distribution Statement

19. Security Classif. (of this report)

Unclassified

20. Security Classif. (of this page)

Unclassified

21. No. of Pages

22. Price

FINAL REPORT | WJE No. 2019.0352.0 | MAY 20, 2022

EXECUTIVE SUMMARY

The Florida Department of Transportation manages a network of over 6,500 bridges within its highway infrastructure system, many of which are constructed in severe corrosive environments. To extend the service life of bridges across the State, FDOT implements various corrosion prevention and control systems, including durability based design requirements of new bridges and rehabilitation efforts for existing bridges. This evaluation included a review of both performance and estimated costs of commonly used materials/systems to identify the most robust, effective, and cost-efficient methods for extending service lives of bridges. In addition field investigations were performed at four locations across the state and included eight individual bridges. These bridges were chosen in order to evaluate the most commonly utilized corrosion prevention and control systems installed in Florida’s coastal environments.

The two corrosion control systems evaluated in this investigation are both cathodic protection installations and include galvanic pile jackets and impressed current jackets typically installed on the footing and/or pile cap elements. Results indicated that galvanic pile jackets are an effective method of mitigating corrosion on pile elements and can extend service life of pile elements by 20 years or more depending on the quality of installation, environment, and maintenance efforts. Similarly, conventional impressed current jackets powered by rectifiers are also effective at mitigating corrosion in larger substructure elements, however, these systems require periodic maintenance and adjustments. In 2020, FDOT replaced the traditional rectifiers with solar panels on select footing elements on three bridges on a trial basis. A review of data regarding one of these systems showed that while the solar powered systems provided some amount of cathodic protection, several limitations prevented the systems from performing comparably to the traditional rectifier-powered systems. Specifically, the solar-powered system did not provide adequate cathodic protection to the structure and daily shifts in provided current based on sunlight availability present challenges to be overcome in developing these systems.

Regarding corrosion prevention mechanisms, primarily those regarding construction materials included in the design of new bridges, this study evaluated performance of epoxy-coated reinforcing and inclusion of fly ash within concrete mix designs. The State has experienced mixed performances of bridges constructed with epoxy-coated reinforcing. This investigation compared a bridge substructure constructed with epoxy-coated reinforcement to a similar sister bridge constructed with traditional uncoated reinforcing steel. This investigation found that installation of epoxy-coated reinforcement has provided a minimum of three years of additional service life, and likely more, prior to repairs or corrosion control mechanisms would need to be considered. Inclusion of fly ash within concrete mix designs provided benefit regarding corrosion control by reducing pore size and increasing resistivity of the concrete, both of which reduce diffusivity of chlorides. However, quantitative conclusions were difficult to ascertain from data obtained during this investigation, as surface coatings unbeknownst to the research team had been applied to the bridge substructures, which likely affected surface concentrations and associated chloride profiles.

All of these results ultimately may lead to new criteria regarding installation, maintenance, and monitoring methods for cathodic protection systems, as well as consideration for construction materials for new bridge designs to increase durability and anticipated service life.

FINAL REPORT | WJE No. 2019.0352.0 | MAY 20, 2022

TABLE OF CONTENTS

Executive Summary

1. Introduction

Research Outline and Objectives

2. Literature Review

Science of Corrosion

Corrosion Control Methodologies

Corrosion Control in Florida Bridges

3. Field Investigations of Corrosion Prevention and Control Programs

Descriptions of Electrical Measurements at Bridges with CP

Descriptions of Test Methods at Bridges without CP

Field Investigation 1 – Gandy and Howard Frankland Bridges

Assessment Objectives and Methodology

Description of Structures and Environment

Description of Galvanic Corrosion Control Systems

Assessment Findings of Galvanic Corrosion Control Systems

Description of Impressed Current Corrosion Control Systems

Assessment Findings of Impressed Current Corrosion Control Systems

Field Investigation 2 – Melbourne Causeway Bridges

Assessment Objectives and Methodology

Description of Structures and Environment

Description of Corrosion Control Systems

Assessment Findings

Field Investigation 3 – EB Sunrise Boulevard, WB Sunrise Boulevard, and St. Andrews Avenue Bridges

Assessment Objectives and Methodology

Description of Structures and Environment

Description of Corrosion Control Systems

Assessment Findings

Field Investigation 4 – Bob Graham Sunshine Skyway Bridge – Trial Solar-Powered ICCP System

Assessment Objectives and Methodology

Description of Structures and Environment

Description of Impressed Current Corrosion Control Systems

FINAL REPORT | WJE No. 2019.0352.0 | MAY 20, 2022

Assessment Findings

4. Review of FDOT Corrosion Prevention and Control Programs

Costs of Installed CP

Damage Analysis of Structures without CP

Damage Analysis of Structures with CP

Data from BIRs for Gandy and Howard Frankland Bridges

Publicly Available Data

5. Comprehensive Assessment of Corrosion Prevention and Control Program

Cathodic Protection – Galvanic Pile Jackets

Cathodic Protection – Impressed Current Systems

Construction Practice – Epoxy-Coated Reinforcing Steel

Construction Practice – Fly Ash Inclusion in Mix Designs

Figures

References

APPENDIX A. Gandy and Howard Frankland Bridges - Pile Jacket Electrical Testing Data

APPENDIX B. Gandy and Howard Frankland Bridges - Visual Observations

APPENDIX C. Gandy and Howard Frankland Bridges - Summarized ICCP Data

APPENDIX D. Melbourne Bridge - Visual Distress, NDE Data, and Sample Locations

APPENDIX E. Melbourne Bridge - Petrographic Examination Report

APPENDIX F. EB Sunrise Blvd, WB Sunrise Blvd, and S. Andrews Ave Bridges - Visual Distress, NDE Data, and Sample Locations

APPENDIX G. EB Sunrise Blvd and WB Sunrise Blvd Bridges - Petrographic Examination Report

FINAL REPORT | WJE No. 2019.0352.0 | MAY 20, 2022 Page 1

LIST OF FIGURES

Figure 1. Florida Department of Transportation Bridge Work Plan for 2015. (Lau et al. 2018)

Figure 2. Schematic of electrochemical chloride extraction

Figure 3. Schematic of electrochemical realkalization (reprinted from Broomfield 1997)

Figure 4. Corrosion protection status chart (adapted from NACE TR21463-2020)

Figure 5. Location of the Gandy and Howard Frankland Bridges across Tampa Bay, identified by the red and yellow star, respectively (image from Google Maps©)

Figure 6. Typical elevation view detail of non-structural CP pile jackets

Figure 7. Typical cross section of non-structural CP pile jackets

Figure 8. Typical elevation view detail of structural CP pile jackets

Figure 9. Typical cross section of structural CP pile jackets

Figure 10. Overview of total current as a function of time

Figure 11. Overview of polarization/depolarization decay as a function of time. The red line indicates the minimum 100 mV polarization/depolarization recommended threshold for adequate CP

Figure 12. Overview of decay potential as a function of time. The red line indicates the maximum -720 mV vs, CSE decay potential recommended threshold for adequate CP

Figure 13. Relative side-by-side comparison of average decay potentials as a function of CP pile jacket elevation. The red line indicates the maximum -720 mV vs. CSE decay potential recommended threshold for adequate CP

Figure 14. Full-height cracking of fiberglass jacket (Pile 289-5 shown)

Figure 15. Sections of fiberglass jacket broken off entirely (Pile 105-9 shown)

Figure 16. Typical vertical cracking propagating upward from top of pile at corner (Pile 198-1 shown)

Figure 17. Example of vertical cracking exhibiting minor rust staining (Pile 236-7 shown)

Figure 18. Cracking of sloped grout material above jacket (Pile 198-1 shown)

Figure 19. Metalizing overspray observed on pile (Pile 14-4 shown)

Figure 20. Plot showing depolarization versus decay potentials measured in the monitoring port for the three generations of installations

Figure 21. Plot showing depolarization versus decay potentials measured in the water for the three generations of installations

Figure 22. Plot showing depolarization versus decay potentials measured in the monitoring port for piles with and without distress

Figure 23. Cross-sectional view of pier footing ICCP system from Drawing Set from Financial Project

ID 420666-1-52-01 (2009 Installation)

Figure 24. Current versus average depolarization measurements for the Gandy Bridge

Figure 25. Location of the Melbourne Causeway Bridges across the Indian River, identified by the red star (image from Google Maps©)

Figure 26. Photographs of evaluated ECR samples from Bridge No. 700181

FINAL REPORT | WJE No. 2019.0352.0 | MAY 20, 2022 Page 2

Figure 27. Representative vertical cracking extending upward from the MGL

Figure 28. Crack width gauge indicating an approximate crack width of 25 mil

Figure 29. Typical cracking of column at elevation of top of strut

Figure 30. Chloride profiles for pile cap core samples. Cores shown are Core 10 (Bridge No. 700174, 2011) and Core 3 (Bridge No. 700181, 2021). The red line indicates an approximate depth of the reinforcing steel (4.25 in.)

Figure 31. Chloride profiles for column core samples. Cores shown are Core 16 (Bridge No. 700174, 2011) and Core 4 (Bridge No. 700181, 2021). The red line indicates an approximate depth of the reinforcing steel (4.25 in.)

Figure 32. Chloride profiles for strut core samples. Cores shown are Core 16 (Bridge No. 700174, 2011) and Core 4 (Bridge No. 700181, 2021). The red line indicates an approximate depth of the reinforcing steel (4.25 in.)

Figure 33. Chloride profiles for crash wall core samples. Cores shown are Core 18 (Bridge No. 700174, 2011) and Core 9 (Bridge No. 700181, 2021). The red line indicates an approximate depth of the reinforcing steel (4.25 in.)

Figure 34. Location of the eastbound and westbound routes of Sunrise Blvd over the intercoastal waterway, identified by the red star (image from Google Maps©)

Figure 35. Location of the eastbound and westbound route of S. Andrews Ave, over New River & New

River Drive, identified by the red star (image from Google Maps©)

Figure 36. Photographs of evaluated ECR samples

Figure 37. A2-1 30-40% Backside Contamination

Figure 38. Core SE3. Thin section photographs show the cement paste composition and micro texture.

Portland cement (red arrows) appeared to be well hydrated. Fly ash was observed (yellow arrows) and estimated at 15 to 25 percent by mass of total cementitious materials. Plane-polarized light for both

Figure 39. Micrograph of Core A2 cross-section with coating thickness measurements

Figure 40. Micrograph of Core SW2 cross-section with coating thickness measurements

Figure 41. Chloride profiles for the core samples. Cores shown are SE1, SE2, SE4, and SE5 (Bridge No.

860467), SW1, SW3, SW4, and SW5 (Bridge No. 860466), and A2 (Bridge No. 860319). The red line indicates an approximate depth of the reinforcing steel (4.50 in.)

Figure 42. Location of the Skyway over Tampa Bay, identified by the red star (image from Google

Maps©)

Figure 43. Overview of solar panels epoxied to the underside of the box girder (photograph provided by FDOT)

Figure 44. Measured output DC voltage data from RMU

Figure 45. Measured potential data from RMU for Zone 1 and Zone 2

FINAL REPORT | WJE No. 2019.0352.0 | MAY 20, 2022 Page 3

Figure 46. Average statewide costs for CP Systems with Titanium Mesh – Impressed Current Systems.

Top, middle, and bottom plots show Electrical Work (Item 0400 60 1), Conduit (Item 0400 60 3), and

Titanium Mesh (Item 0400142 7), respectively

Figure 47. Average statewide costs for CP Systems with Zinc Aluminum Spray – Galvanic Arc-Spray

Metalizing Systems. Zinc Aluminum Spray (Item 0400142 3) shown

Figure 48. Average statewide costs for CP Systems with Zinc Anode Assemblies – Galvanic Systems.

Pile Zinc Anode Assemblies (Item 0455 81101) and Pier Zinc Anode Assemblies (Item 0455 81102) shown

Figure 49. Average statewide costs for CP Integral Pile Jackets – Galvanic Systems. Top and bottom plots show Non-Structural Pile Jackets 16.1” to 30” (Item 0457 2121) and Structural Pile Jackets up to

16” (0457 2211), 16.1” to 30” (0457 2221), and greater than 30” (Item 0457 2231) shown, respectively. .. 104

Figure 50. Statistical comparison of elemental distress as a function of bridge age and construction materials for column elements (EN = 205)

Figure 51. Statistical comparison of elemental distress as a function of bridge age and construction materials for pile cap/footing elements (EN = 220)

Figure 52. Statistical comparison of elemental distress as a function of bridge age and construction materials for pile elements (EN = 226)

Figure 53. Statistical comparison of elemental distress as a function of bridge age and construction materials for pier cap elements (EN = 234)

Figure 54. Statistical comparison of elemental distress as a function of cumulative data for pile cap/footing (EN = 220)

Figure 55. Statistical comparison of elemental distress as a function of cumulative data for prestressed and reinforced concrete pile (EN = 226/227)

Figure 56. Statistical comparison of elemental distress as a function of cumulative data for pile jackets

(EN = 8298)

Figure 57. Statistical comparison of elemental distress as a function of cumulative data and installation system for piles (EN = 226/227)

Figure 58. Sample 137-7. Close-up view of zinc mesh shows its condition and thickness measurements. The mesh showed localized corrosion and minor section loss near the corner. Mesh was free of significant corrosion or section loss elsewhere. Arrows indicate corroded portion

Figure 59. Sample 177-4. Close-up view of zinc mesh shows its condition and thickness measurements. Very localized corrosion and minor section loss were observed. Red arrows indicate locally corroded zinc. White efflorescence was also observed on the lapped section (yellow circle)

Figure 60. Sample 182-3. Close-up views of zinc mesh show its condition and thickness measurements. Localized corrosion and section loss were observed. Red arrows indicate corroded or partially corroded zinc

Figure 61. Sample 21-1. Close-up views of zinc mesh show its condition and thickness measurements.

Frequent corrosion and minor section loss were observed. Red arrows indicate corroded zinc. Yellow

FINAL REPORT | WJE No. 2019.0352.0 | MAY 20, 2022 Page 4 arrows indicate a delamination crack lined with secondary deposits, liekly due to corrosion of the zinc mesh

Figure 62. Sample 53-3. Close-up views of zinc mesh show its condition and thickness measurements.

A mesh joint appeared to be present at a corner of the concrete sample (top photo). Corrosion and minor section loss were observed

Figure 63. Sample 270-2. Close-up view of zinc mesh shows its condition and thickness measurements. Generally free of significant corrosion or section loss

Figure 64. Sample 82-6. Close-up views of zinc mesh show its condition and thickness measurements.

Corrosion and minor section loss were observed at the corner (top photo); less corrosion and section loss along the two edges (bottom photos)

Figure 65. Sample 106-7. Close-up view of zinc mesh shows its condition and thickness measurements. Widespread corrosion and significant section loss were observed. Red arrows indicate white deposits suspected to be zinc corrosion product

Figure 66. Sample 138-8. Close-up view of zinc mesh shows its condition and thickness measurements. Corrosion and minor section loss were observed

Figure 67. Representative titanium mesh sample (Gandy 226)

Figure 68. Microscopic view of titanium mesh, including thickness measurements (Gandy 226)

Figure 69. Microscopic view of titanium mesh cross section, including thickness measurements (HF

158)

Figure 70. Missing portion of pile jacket (Pile 12-1)

Figure 71. Vertical cracking with rust staining extending upward from top of pile (Pile 12-1)

Figure 72. Split pile jacket near waterline (Pile 14-4)

Figure 73. Split pile jacket and multiple vertical cracks on pile (Pile 44-5)

Figure 74. Cracking measured up to approximately 50 mil wide (Pile 44-5)

Figure 75. Vertical splitting of jacket (Pile 53-3)

Figure 76. Overview photograph of pile and jacket with no noted distress (Pile 65-8)

Figure 77. Jacket splitting and missing around lower perimeter of pile (Pile 73-5)

Figure 78. Overview photograph of apparent jacket extension on top (Pile 80-6)

Figure 79. Overview photograph of pile and jacket with no noted distress (Pile 99-9)

Figure 80. Significant distress of jacket (Pile 105-9)

Figure 81. Overview photograph of pile and jacket with no noted distress (Pile 116-4)

Figure 82. Significant distress of jacket (Pile 120-1)

Figure 83. Exposed grout exhibiting staining and cracking (Pile 120-1)

Figure 84. Minor spall on the SW corner top that was metalized over (Pile 123-8)

Figure 85. Jacket extension on top, no distress noted (Pile 129-6)

Figure 86. Significant distress of jacket (Pile 133-5)

Figure 87. Repair on NW corner of the pile (Pile 138-7)

FINAL REPORT | WJE No. 2019.0352.0 | MAY 20, 2022 Page 5

Figure 88. Vertical splitting of jacket (Pile 138-8)

Figure 89. Horizontal splitting of jacket (Pile 177-4)

Figure 90. Vertical cracking of jacket (Pile 182-3)

Figure 91. Cracking measured up to approximately 20 mil wide and spalling of pile (Pile 190-6)

Figure 92. Vertical cracking of jacket (Pile 191-3)

Figure 93. Repair and cracking measured up to approximately 30 mil wide (Pile 198-1)

Figure 94. Overview photograph of pile and jacket with no noted distress (Pile 214-3)

Figure 95. Repairs with corroded anchors on pile (Pile 214-6)

Figure 96. Vertical cracking of the pile (Pile 236-7)

Figure 97. Two vertical cracks of the pile measured up to approximately 5 mil wide (Pile 263-1)

Figure 98. Cracking measured up to approximately 50 mil wide with corrosion staining (Pile 270-2)

Figure 99. Overview photograph of pile and jacket with no noted distress (Pile 289-2)

Figure 100. Vertical full length splitting of the jacket (Pile 289-5)

Figure 101. Cracking in repair of pile (Pile 304-4)

Figure 102. Cracking in repair on top of pile (Pile 308-5)

Figure 103. Repair on pile corner (Pile 316-8)

Figure 104. Missing bottom of jacket (Pile 46-3)

Figure 105. Cracking measured up to approximately 25 mil wide (Pile 82-6)

Figure 106. Jacket opening at the bottom (Pile 85-4)

Figure 107. Spalling of pile (Pile 85-4)

Figure 108. Jacket broken at the bottom Pile 94-3)

Figure 109. Cracking of pile (Pile 94-3)

Figure 110. Cracking on repair of pile (Pile 104-1)

Figure 111. Corner cracking of pile (Pile 106-7)

Figure 112. Parge coat cracking, no pile cracking noted (Pile 137-4)

Figure 113. Cracking on pile (Pile 144-4)

Figure 114. Core 1. Exterior (exposed) surface (top photo) and interior surface (bottom photo). Arrows indicate imprint of coated deformed steel reinforcing bar, with essentially no to minimal stains or corrosion rust. The fractured surface extended mainly through coarse aggregate particles, consistent with a tight paste-aggregate bond. As-received

Figure 115. Core 1. Side view. Exterior end of the core is on the left. Arrows indicate the imprint of the rebar

Figure 116. Core 1. Exterior (exposed) surface (top photo) and interior surface (bottom). Arrows indicate surface spalling or loss that was probably due to coring. The fractured surface extended mainly through coarse aggregate particles, consistent with a tight paste-aggregate bond. Orange arrows indicate hairline cracks. As-received

FINAL REPORT | WJE No. 2019.0352.0 | MAY 20, 2022 Page 6

Figure 117. Core 1. Side view. Exterior end of the core is on the left. Arrows indicate the imprint of the rebar

Figure 118. Core 1. Lapped cross section and matching saw-cut section stained with phenolphthalein solution to determine the depth of carbonation, which was less than 0.1 inch. Distribution of paste and aggregate appeared to be uniform and the concrete was well consolidated

Figure 119. Core 10. Lapped cross section and matching saw-cut section stained with phenolphthalein solution to determine the depth of carbonation, which was approximately 0.3 inch as indicated by red arrows. Distribution of paste and aggregate appeared to be uniform and the concrete was well consolidated

Figure 120. Core 1 and Core 10. Lapped cross sections show the overall similarity between the two cores

Figure 121. Core 1. Closeup view of the exterior region shows the appearance of aggregate, paste, air voids, and a discolored, carbonated top layer measuring 42.5 mils (0.043 inch). Arrows indicate air voids of varying size

Figure 122. Core 10. Closeup view of the exterior region shows the appearance of aggregate, paste, air voids, and a discolored, carbonated top layer measuring approximately 300 mils (0.3 inch). Arrows indicate short vertical cracks/microcracks

Figure 123. Core 1. Thin section photographs show the cement paste composition and micro texture.

Portland cement (arrows) appeared to be well hydrated. No supplementary cementitious materials were observed. Top photo: plane-polarized light. Bottom photo: cross-polarized light

Figure 124. Core 1. Thin section photographs show the cement paste composition and micro texture.

Portland cement (arrows) appeared to be well hydrated. No supplementary cementitious materials were observed. Top photo: plane-polarized light. Bottom photo: cross-polarized light

Figure 125. Core SE-3. Exterior (exposed) surface (top photo) and interior surface (bottom photo).

Arrows indicate a thin layer of light-gray coating. The interior fractured surface extended mainly through coarse aggregate particles, consistent with a tight paste-aggregate bond. As-received for examination

Figure 126. Core SE-3. Side view. Exterior end of the core is on the left

Figure 127. Core SW-2. Exterior (exposed) surface (top photo) and interior surface (bottom). The interior fractured surface extended mainly through coarse aggregate particles, consistent with a tight paste-aggregate bond. Orange arrows indicate a partially exposed No. 5 reinforcing steel bar

Figure 128. Core SW-2. Side view. Exterior end of the core is on the left. Arrows indicate the reinforcing steel bar

Figure 129. Lapped cross sections of the two cores show the overall appearance and condition of the concrete in each core. Distribution of paste and aggregate appears to be uniform and the concrete in each core is overall well consolidated. The exterior ends are on the left

Figure 130. Saw-cut cross sections stained with phenolphthalein solution (left portion in each core) and a rainbow solution to determine the depth of carbonation. Carbonation was 0.4 to 0.5 inch in

Core SW-2 and 0.2 to 0.3 inch in Core SE-3, as indicated by the color variation (red arrows)

FINAL REPORT | WJE No. 2019.0352.0 | MAY 20, 2022 Page 7

Figure 131. Core SE-3. Closeup views of the exterior region show the appearance of aggregate, paste, air voids, a marginally discolored, carbonated top layer measuring 216.8 mils (0.22 inch), and a light-gray coating layer (red arrows). Yellow arrows indicate air voids

Figure 132. Core SW-2. Closeup views of the exterior region show the appearance of aggregate, paste, air voids, a marginally discolored, carbonated top layer measuring 432.3 mils (0.43 inch), and a light-gray coating layer (red arrows). Abundant small spherical air voids were observed (yellow arrows), consistent with air-entrainment

Figure 133. Core SE-3. Thin section photographs show the cement paste composition and micro texture. Portland cement (red arrows) appeared to be well hydrated. Fly ash was observed (yellow arrows) and estimated at 15 to 25 percent by mass of total cementitious materials. Plane-polarized light for both

FINAL REPORT | WJE No. 2019.0352.0 | MAY 20, 2022 Page 8

LIST OF TABLES

Table 1. Summary of Applicable AASHTO Minimum Covers for Main Reinforcing Steel

Table 2. Bridge Selection by Field Investigation

Table 3. Corrosion Control Systems Matrix

Table 4. Typical Half-Cell Potential Data Ranges

Table 5. Half-Cell Potential Corrosion Risk

Table 6. Interpretation of Resistivity Measurements

Table 7. Bridge Descriptions

Table 8. Detailing Information for Gandy Bridge

Table 9. Detailing Information for HF Bridge

Table 10. Summary of Jacket Installation History

Table 11. Inventory of Piles with Detailed Routine Monitoring Data

Table 12. Gandy and HF Galvanic Pile Jacket CP Test Data Summary – 2001 Install

Table 13. Gandy and HF Galvanic Pile Jacket CP Test Data Summary – 2005 Install

Table 14. Gandy and HF Galvanic Pile Jacket CP Test Data Summary – 2009 Install

Table 15. Percent Change in Measurement from Initial Installation to 2020

Table 16. Summarized Data for CP Pile Jackets Selected for In-Depth Assessment – 2001 Installation

Table 17. Summarized Data for CP Pile Jackets Selected for In-Depth Assessment – 2005 Installation

Table 18. Summarized Data for CP Pile Jackets Selected for In-Depth Assessment – 2009 Installation

Table 19. Material Evaluation Summary

Table 20. ICCP System Installation Dates

Table 21. Distribution of Embedded Reference Electrodes in Gandy Bridge (Zone 1, 2009 Install Only)

Table 22. Distribution of Embedded Reference Electrodes in Howard Frankland Bridge (Zone 1, 2009

Install Only)

Table 23. Summary of 2009 ICCP Commissioning Data

Table 24. Comparison of Average Rectifier Outputs

Table 25. Comparison of Average Potential Measurements

Table 26. Summary of Average Potential Measurements from 2021

Table 27. Count of Reference Cells

Table 28. Summary of Average Potential Measurements for Select Piers

Table 29. Bulk Resistivity Data for Jacket Concrete Material

Table 30. Components Selected for Comprehensive Testing and Sampling

Table 31. Bridge Descriptions

Table 32. Results of ECR Evaluation

Table 33. Measured Concrete Cover Ranges

Table 34. General Core Characteristics and Petrographic Findings

FINAL REPORT | WJE No. 2019.0352.0 | MAY 20, 2022 Page 9

Table 35. Average Measured Surface Resistivity

Table 36. Reproduced Results of Laboratory Testing of Water Sample

Table 37. Tabulated Delamination Quantities

Table 38. Core Sampling and Condition of Reinforcing Steel on Bridge No. 700174 (Concorr 2011)

Table 39. Core Sampling and Condition of Reinforcing Steel on Bridge No. 700181 (Concorr 2011)

Table 40. Core Sampling and Condition of Reinforcing Steel on Bridge No. 700181 (2021)

Table 41. Bridge Descriptions

Table 42. Results of ECR Evaluation

Table 43. Measured Concrete Cover Ranges

Table 44. General Core Characteristics and Petrographic Findings

Table 45. Average Measured Surface Resistivity Closest to High Water Line

Table 46. Acid-Soluble Chloride Contents

Table 47. Bridge Description

Table 48. Summary of Pier 116 RMU Data during Investigation Time Frame

Table 49. Summary of Manually-Obtained Electrochemical Measurements

Table 50. Tabulated Costs for Select Pay Items Statewide (2016 – 2020)

Table 51. Average Costs for Select Pay Items Statewide (2016 – 2020)

Table 52. Bridge List for Elemental Data Comparison

Table 53. Bridge List for Galvanic CP Pile Jackets

Table 54. Gandy Bridge – Summary of Voltage and Resistance Measurement Data

Table 55. HF Bridge – Summary of Voltage and Resistance Measurement Data

Table 56. Summary of Potential Data from Permanent Reference Electrodes

Table 57. Summary of Potential Data from External Reference Electrodes

Table 58. General Core Characteristics and Petrographic Findings

Table 59. General Core Characteristics and Petrographic Findings

FINAL REPORT | WJE No. 2019.0352.0 | MAY 20, 2022 Page 10

1. INTRODUCTION

Corrosion of steel in reinforced concrete bridges is a significant concern for the structural integrity, long-term durability, and maintenance of the Florida highway infrastructure. For example, statistics from a national study in 2002 indicated that approximately 15% of the national bridge inventory is structurally deficient because of corrosion, and the national annual direct cost exceeded $8 billion (Koch et al. 2002).

As a result, research and recommendations have been made by technical organizations such as American

Concrete Institute (ACI), Federal Highway Administration (FHWA), NACE International, and National

Cooperative Highway Research Program (NCHRP) to promote corrosion durability of highway bridge infrastructures.

Transportation infrastructure costs typically exceed 10% of Florida’s state budget. Florida’s 2020-2021 fiscal year budget includes $9.9 billion to be allocated to the Florida Department of Transportation (FDOT), including $436.2 million for scheduled repairs of 57 bridges and replacement of 18 bridges and $2.8 billion for highway construction (Druga 2019). The typical design life expectation for the >6,500 bridges in the state highway infrastructure exceeds 50 years; however, approximately half of the bridges are in aggressive marine service. There is a need to continue to improve designs to control corrosion and develop tools to assess future performance and maintenance needs.

In Florida, corrosion is pervasive in many of the environments where transportation infrastructure exists, including buried steel and concrete pipes in soil, steel bridge superstructure and bearings, mechanically stabilized earth walls, steel cables and wires, steel piling, concrete tunnel segments, reinforced concrete decks, and pour-backs as well as reinforced concrete substructures. The corrosion mechanisms vary significantly due to the multitude of engineered highway systems with varying exposure environments, chemistry, and construction materials. However, of the many engineering systems in the state highway infrastructure, bridge substructures are most critically affected by corrosion of reinforcing steel. This critical nature is partly due to its high visibility to the general public, especially for highway bridges that serve public and private enterprises in large populations along the coast. Such highway bridges are vulnerable to aggressive coastal environments. Of the national annual direct costs for highway bridges, $2 billion was related to steel corrosion in bridge concrete substructures (Tinnea et al. 2006). The Florida bridge work plan identified bridge substructure repair as the second-highest maintenance need (Figure 1)

(Lau et al. 2018).

FINAL REPORT | WJE No. 2019.0352.0 | MAY 20, 2022 Page 11

Figure 1. Florida Department of Transportation Bridge Work Plan for 2015. (Lau et al.

2018).

Continuing research by FDOT has advanced the engineering practice for corrosion control, especially for reinforced concrete substructures, and improved material specifications and design practices have been implemented over the last 30 years. These positive changes have provided safer and more durable structures. The maintenance of newer systems is not as intensive as for older bridges. Complexities of modern structural systems, the highly aggressive Florida exposure environments, changes in building and material technologies, and sometimes variability in construction quality provide bridge preservation challenges. Therefore, it is highly advantageous to evaluate the performances of implemented corrosion control measures in Florida bridges so that the most robust and effective methods for extending the service life of bridges can be identified.

Research Outline and Objectives

The overarching project objective is to determine the effectiveness of the current corrosion prevention and control programs used by the State. For this study, the research team has inspected eight bridges and considered the effects of improved construction practices and cathodic protection on bridges across the

State. The following tasks which have been conducted outline the project objectives:

Task 1 - Literature Review: The project team used its experience and familiarity with Florida infrastructure to conduct a review of literature that considers FDOT corrosion mitigation procedures.

Task 2 - Site Visits: Working with FDOT, the project team identified bridges and systems for site inspection. Care was taken to limit the number of variables associated with each assessment in an effort to optimize the validity of the comparisons being made between the various bridges/CP systems.

FINAL REPORT | WJE No. 2019.0352.0 | MAY 20, 2022 Page 12

Task 3 - Cost of Installed CP: The project team analyzed design documents, BIRs, and other documents to determine an approximate order of magnitude lifetime cost estimate for each applicable CP system studied. The research team worked with FDOT to identify what CP systems/combinations are included and what life should be associated with the cost.

Tasks 4 and 5 - Analysis of Structures with and without Cathodic Protection: Data mining of

FDOT and other state resources has been carried out to estimate the service life of structures with and without CP. The research team has worked with FDOT to define threshold criteria for a service life that is applicable to FDOT’s needs.

Task 6 - Comprehensive Assessment of Corrosion Prevention and Control Program: The project team used its expertise and the knowledge gained through the previous tasks to quantify the effectiveness of the current FDOT corrosion prevention and control programs and summarize our findings.

Task 7 and 8 - Draft Final, Closeout Teleconference, and Final Report: This final report will be submitted to FDOT for review, and a conference call will be held regarding the findings.

2. LITERATURE REVIEW

This literature review begins with a summary of the fundamental scientific principles that describe corrosion and corrosion control methodologies that have been developed. Following this, a review of the corrosion control methods used in Florida bridges and the implemented cathodic protection system are detailed. This review is intended to be comprehensive regarding the background and types of corrosion prevention systems used throughout Florida.

Science of Corrosion

To understand the corrosion degradation of reinforced concrete and application of mitigation technologies, the basics of the electrochemistry of these systems should be considered. At the most basic level, corrosion of the rebar in concrete is due to the development of an electrochemical cell that is made of the steel rebar and the concrete pore water. The cell supports two basic half-cell reactions:

Fe → Fe2+ + 2e- Equation 1

2H2O + O2 +2e- → 4OH- Equation 2

Equation 1 represents the anodic reaction that accounts for the material loss of the rebar, and Equation 2 represents the supporting cathodic oxygen reduction reaction. The components of the electrochemical cell are described next.

Steel Rebar Anode

The iron oxidation reaction occurs at portions of the steel rebar that serve as an anode. Very slow anodic reactions typically occur on steel rebar embedded in concrete when the steel is in a passive state due to the formation of a thin protective layer of iron hydroxides and oxides. However, chemical changes in the concrete pore water surrounding the steel rebar can disrupt the passive layer. In marine environments, this depassivation occurs when a critical level of chloride ions penetrate through the concrete cover to the surface of the steel rebar. A wide range of critical chloride threshold (CT) values have been reported

(Angst et al. 2009), but values near 0.08% to 0.20% by weight cement content have been used by various

FINAL REPORT | WJE No. 2019.0352.0 | MAY 20, 2022 Page 13 design and guideline documents. The effective CT may vary depending on several parameters, including polarization levels, pore water pH, and the binding capacity of the cement paste to entrap chloride ions from the solution. Engineering approaches require practical considerations so that CT may be used based on total chloride levels relative to cement content or by concrete volume. Still, it is important to recognize some uncertainty inherent in this approach.

The number of chloride ions penetrating the concrete cover is influenced by the concrete material, the reinforced concrete element geometry, and the severity of exposure to chloride ion sources. Reinforced concrete bridge substructure elements in marine environments have different exposure zones to water chloride ions and other potential contaminants. These zones include the submerged region, tidal region, splash region, and atmospheric region. Chloride ion diffusion and permeation can account for chloride ingress in concrete in the submerged region due to the chloride ion concentration gradient in the concrete pore water and the hydraulic pressure of the water. Chloride transport in concrete in the atmospheric regions where direct contact with water does not occur is much lower. In the tidal and splash regions, the cyclic wetting and drying allow for the salt concentration on the near-surface of the concrete to be significantly larger, which can be as high as 1.6 lb/ft3 (Sagüés et al. 2001). This increase in the surface concentration of chloride ions promotes more rapid chloride ingress relative to the submerged and atmospheric regions.

Therefore, a localized region of depassivated steel often develops in the tidal and splash regions and produces locally high corrosion rates. This accounts for typical field observations where the concrete delamination and spalling typically occur in the tidal and splash zones.

Steel Rebar Cathode and Electrical Conductor

The anodic iron oxidation reaction is supported by the oxygen reduction reactions that occur on the surface of the reinforcing steel, typically relatively near the anode. Dissolved oxygen in the concrete pore water reacts, as shown in Equation 2, and the amount of available oxygen can control the rate of this reaction. Generally, the amount of available oxygen is greater in the splash/tidal and atmospheric regions than in the submerged regions. The greater access to oxygen helps accelerate corrosion in the tidal/splash zone, where the steel surface has been depassivated by the presence of chlorides.

The rebar itself acts as an electrical conductor that connects the anode portion of the rebar to its cathode surfaces. Large extended cathodes are available due to the long length of longitudinal rebar as well as the electrical coupling of other rebars by stirrups and tie wire. The large cathode surface area throughout the structure allows for larger rates of reduction reactions that, in turn, encourage polarization to occur and increase the iron oxidation rate at the anode site. This macro-cell coupling of the anode and the extended array of cathodes supports rapid corrosion.

Electrolyte and Ionic Bridge

The electrolyte, as part of the electrochemical cell, is made up of the concrete pore water that remains in the macro-, capillary-, and gel-pores of the hardened concrete. The concrete pore water is typically alkaline, greater than pH 13 during casting, and greater than pH 12 for mature concretes. As mentioned before, steel can develop a passive protective layer at these pH levels, but this can be compromised by chemical changes, including the accumulation of chloride ions.

FINAL REPORT | WJE No. 2019.0352.0 | MAY 20, 2022 Page 14

The concrete pore water creates the ionic path that allows the completion of the electrical circuit (i.e., electrons flow from the anode to the cathode via the rebar itself, and ionic flow develops in the pore water). Concretes with low permeability create a less conductive ionic path. The polarization that occurs due to the coupling of the anode and cathode is reduced due to the voltage drop that occurs in concretes with high electrical resistivity. This loss in polarization reduces the rate of iron oxidation.

Corrosion Control Methodologies

Corrosion of steel in reinforced concrete substructures in marine exposure is largely associated with chloride-induced corrosion. However, carbonation-induced corrosion can occur in substructure components away from splash, where less moisture intrusion occurs. Cracking can also affect the overall corrosion durability of an element.

Corrosion control measures often address means to extend the time to corrosion initiation as the associated corrosion engineering principles are widely understood. The most common approaches include increasing the time it takes for chloride transport to the reinforcing steel surface. This can be accomplished by increasing the concrete cover, utilizing less permeable materials such as concrete incorporating supplementary cementitious materials (SCMs), or applying coatings or overlays on the concrete. Also, it is possible to increase the critical chloride threshold levels for corrosion initiation by using corrosion-resistant steel alloys and the application of coatings on the rebar. Other approaches include the application of admixed inhibitors to develop surface films or modify electrochemical characteristics of the corrosion system. Active approaches to delay or prevent corrosion initiation include the application of electrochemical techniques, such as cathodic protection (CP), chloride extraction, and realkalization.

CP and the use of inhibitors may also be considered as methods to reduce corrosion rates and extend the time to corrosion propagation. Crack repairs on concrete substructures may also delay the development of corrosion-related damage. Crack repair techniques can include epoxy injection and penetrating sealers.

The following sections describe, in detail, design specification and corrosion control methodologies that have been developed and implemented in Florida.

Concrete Structure Design and Construction

The design and detailing of reinforced and prestressed concrete elements play a critical role in determining the service life of the structures. In addition to corrosion-inhibiting admixtures and sealers discussed previously, factors affecting the corrosion resistance of reinforced and prestressed concrete elements include, but are not limited to, concrete mix designs, reinforcing steel cover depth, and method of curing for precast concrete elements.

Concrete Mix Designs

The typical constituents to produce concrete include aggregate, cement, water, SCMs, and admixtures.

Each constituent's physical and chemical properties can vary depending on the source; quantities of each can be adjusted and modified, which can make the development of concrete mix designs challenging to meet the strength, durability, and corrosion resistance requirements of a given element.

FINAL REPORT | WJE No. 2019.0352.0 | MAY 20, 2022 Page 15

To produce reinforced concrete structures resistant to corrosion, there are several critical components. The first of which is the water-to-cementitious material ratio (w/c), which is the ratio of the weight of water versus that of cement plus any SCMs. Typical values of w/c in conventional concrete are approximately

0.25 to 0.55. As part of the 1987 FHWA study, corrosion resistance of sample specimens with varying w/c was investigated. Samples were cast with w/c = 0.51, 0.40, and 0.28, and test results found that long-term chloride permeability to the 1-inch depth was reduced by approximately 80 and 95 percent when w/c was lowered from 0.51 to 0.40 and to 0.28, respectively (Pfeifer et al. 1987). The study concluded that after corrosion activity was started under a given set of conditions, the subsequent severity of the corrosion process was reduced significantly for lower w/c concrete samples. This included both conventional concrete and samples containing calcium nitrate and recommended to use w/c in the 0.44 to 0.32 range for substructure concrete members and new precast, prestressed concrete members for bridges.

A second important variable of concrete mix design is the use of SCMs, which can improve the workability of plastic concrete, increase strength, and lower permeability, leading to improved resistance to chloride ion ingress. The three most common SCMs today are slag cement, fly ash, and silica fume, which are byproducts of steel production, coal combustion, and the production of silicon metal or similar alloys.

Each of these SCMs participates in different chemical reactions within the paste of the concrete; however, each generally serves to fill capillaries and reduce pore size, thus reducing the permeability of the concrete. Another conclusion from the 1987 FHWA study was that reinforcing steel in slabs that contained silica fume did not develop corrosion. Chloride contents at the 1-inch or greater depth were reduced by about 98 percent after the year-long cyclic saltwater exposure test when compared to the same conventional mix design without silica fume (Pfeifer et al. 1987).