HUMECTANTS TO AUGMENT CURRENT FROM METALLIZED ZINC CATHODIC PROTECTION SYSTEMS ON CONCRETE Final Report SPR 384 HUMECTANTS TO AUGMENT CURRENT FROM METALLIZED ZINC CATHODIC PROTECTION SYSTEMS ON CONCRETE Final Report SPR 384 by Gordon R. Holcomb, Bernard S. Covino, Jr., Stephen D. Cramer, James H. Russell, Sophie J. Bullard, and W. Keith Collins Albany Research Center, U. S. Department of Energy, Albany OR 97321 Jack E. Bennett J. E. Bennett Consulting, Inc., Chardon OH 44024 Steven M. Soltesz and H. Martin Laylor Oregon Department of Transportation, Salem OR 97301 for Oregon Department of Transportation, Research Group 200 Hawthorne SE, Suite B-240 Salem OR 97301-5192 and Federal Highway Administration Washington, D.C. December 2002 Technical Report Documentation Page 1. Report No. 2. Government Accession No. 3. Recipient’s Catalog No. FHWA-OR-RD-03-08 4. Title and Subtitle 5. Report Date Humectants to Augment Current from Metallized Zinc Cathodic Protection December 2002 Systems on Concrete 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No. Gordon R. Holcomb, Bernard S. Covino, Jr., Stephen D. Cramer, James H. Russell, Sophie J. Bullard, and W. Keith Collins Albany Research Center, U. S. Department of Energy, Albany OR 97321 Jack E. Bennett, J. E. Bennett Consulting, Inc., Chardon OH 44024 Steven M. Soltesz and H. Martin Laylor, Oregon Department of Transportation, Salem OR 97301 9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) Oregon Department of Transportation Research Group 11. Contract or Grant No. 200 Hawthorne Avenue SE, Suite B-240 SPR 384 Salem, Oregon 97301-5192 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered Oregon Department of Transportation Federal Highway Administration Final Report Research Group and 400 Seventh Street S.W. 200 Hawthorne Avenue SE, Suite B-240 Washington, DC 20590 14. Sponsoring Agency Code Salem, Oregon 97301-5192 15. Supplementary Notes 16. Abstract Cathodic protection (CP) systems using thermal-sprayed zinc anodes are employed to mitigate the corrosion process in reinforced concrete structures. However, the performance of the anodes is improved by moisture at the anode-concrete interface. Research was conducted to investigate the effect of hydrophilic chemical additives, humectants, on the electrical performance and service life of zinc anodes. Lithium bromide and lithium nitrate were identified as feasible humectants with lithium bromide performing better under galvanic CP and lithium nitrate performing better under impressed current CP. Both humectants improved the electrical operating characteristics of the anode and increased the service life by up to three years. 17. Key Words 18. Distribution Statement Thermal-Spray, Zinc, Cathodic Protection, Yaquina Bay Copies available from NTIS, and online at Bridge, Humectant, Lithium Bromide, Lithium Nitrate, http://www.odot.state.or.us/tddresearch Potassium Acetate, Corrosion 19. Security Classification (of this report) 20. Security Classification (of this page) 21. No. of Pages 22. Price Unclassified Unclassified 122 + Appendix Technical Report Form DOT F 1700.7 (8-72) Reproduction of completed page authorized Printed on recycled paper i SI* (MODERN METRIC) CONVERSION FACTORS APPROXIMATE CONVERSIONS TO SI UNITS APPROXIMATE CONVERSIONS FROM SI UNITS Symbol When You Know Multiply By To Find Symbol Symbol When You Know Multiply By To Find Symbol LENGTH LENGTH in inches 25.4 millimeters Mm mm millimeters 0.039 inches in ft feet 0.305 meters M m meters 3.28 feet ft yd yards 0.914 meters M m meters 1.09 yards yd mi miles 1.61 kilometers Km km kilometers 0.621 miles mi AREA AREA in2 square inches 645.2 millimeters squared mm2 mm2 millimeters squared 0.0016 square inches in2 ft2 square feet 0.093 meters squared m2 m2 meters squared 10.764 square feet ft2 yd2 square yards 0.836 meters squared m2 ha hectares 2.47 acres ac ac acres 0.405 hectares Ha km2 kilometers squared 0.386 square miles mi2 mi2 square miles 2.59 kilometers squared km2 VOLUME VOLUME mL milliliters 0.034 fluid ounces fl oz fl oz fluid ounces 29.57 milliliters ML L liters 0.264 gallons gal gal gallons 3.785 liters L m3 meters cubed 35.315 cubic feet ft3 ft3 cubic feet 0.028 meters cubed m3 m3 meters cubed 1.308 cubic yards yd3 yd3 cubic yards 0.765 meters cubed m3 MASS NOTE: Volumes greater than 1000 L shall be shown in m3. g grams 0.035 ounces oz MASS kg kilograms 2.205 pounds lb oz ounces 28.35 grams g Mg megagrams 1.102 short tons (2000 lb) T lb pounds 0.454 kilograms kg CHARGE DENSITY T short tons (2000 lb) 0.907 megagrams Mg kC/m2 kilocoulombs/m2 0.02581 amp-hours per ft2 A-hr/ft2 CHARGE DENSITY TEMPERATURE (exact) A-hr/ft2 Amp-hours per ft2 38.75 kilocoulombs/m2 kC/m2 LC Celsius temperature 1.8C + 32 Fahrenheit LF TEMPERATURE (exact) LF Fahrenheit 5(F-32)/9 Celsius temperature LC temperature * SI is the symbol for the International System of Measurement (4-7-94 jbp) ii ACKNOWLEDGEMENTS The authors wish to thank John Westall of Oregon State University for several helpful discussions about humectant thermodynamics. DISCLAIMER This document is disseminated under the sponsorship of the Oregon Department of Transportation and the United States Department of Transportation in the interest of information exchange. The State of Oregon and the United States Government assume no liability of its contents or use thereof. The contents of this report reflect the views of the authors, who are responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect the official policies of the Oregon Department of Transportation or the United States Department of Transportation. The State of Oregon and the United States Government do not endorse products of manufacturers. Trademarks or manufacturers’ names appear herein only because they are considered essential to the object of this document. This report does not constitute a standard, specification, or regulation. iii iv HUMECTANTS TO AUGMENT CURRENT FROM METALLIZED ZINC CATHODIC PROTECTION SYSTEMS ON CONCRETE TABLE OF CONTENTS 1.0 INTRODUCTION..................................................................................................................1 1.1 BACKGROUND .................................................................................................................1 1.1.1 Bridge Rehabilitation with Cathodic Protection in Oregon ........................................1 1.1.2 Cathodic Protection Processes.....................................................................................2 1.1.3 Humectants ..................................................................................................................3 1.2 PROBLEM DEFINITION...................................................................................................3 1.3 STUDY OBJECTIVES........................................................................................................4 1.4 WORK PLAN SYNOPIS ....................................................................................................4 1.4.1 Long-term Laboratory Experiments (ARC) ................................................................5 1.4.2 Short-Term Chamber Experiments (ARC)..................................................................5 1.4.3 Long-Term Laboratory GCP Experiments (Ohio) ......................................................5 1.4.4 Yaquina Bay Bridge Field Trial (Oregon)...................................................................6 2.0 HUMECTANT SCREENING (OHIO)................................................................................7 2.1 SCREEN STUDY PROCEDURES.....................................................................................7 2.2 SCREENING STUDY RESULTS ......................................................................................8 2.3 SELECTED HUMECTANTS .............................................................................................9 3.0 HUMECTANT THERMODYNAMICS............................................................................11 3.1 WATER ABSORPTION ...................................................................................................11 3.2 BROMIDE OXIDATION..................................................................................................12 4.0 EXPERIMENTAL PROCEDURES ..................................................................................15 4.1 LONG-TERM LABORATORY EXPERIMENTS (ARC) ...............................................15 4.1.1 New Sample Preparation ...........................................................................................15 4.1.2 Aged Sample Preparation..........................................................................................16 4.1.3 Humectant Application..............................................................................................17 4.1.4 Environmental Conditions.........................................................................................17 4.1.5 Accelerated Impressed Current Cathodic Protection ................................................18 4.1.6 Cyclic Impressed Current Cathodic Protection .........................................................18 4.1.7 Galvanic Cathodic Protection....................................................................................18 4.1.8 Depolarization ...........................................................................................................19 4.1.9 Microscopy................................................................................................................20