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Publication Number:  FHWA-HRT-15-079     Date:  June 2018
Publication Number: FHWA-HRT-15-079
Date: June 2018

 

Laboratory Evaluation of Corrosion Resistance of Various Metallic Dowel Bars

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FOREWORD

This report presents findings on a corrosion study related to the corrosion resistance of eight types of metallic dowel bars. The accelerated laboratory corrosion testing was performed using seven small-scale concrete slabs that simulated typical concrete pavements for 452 d of a modified Southern Exposure followed by a detailed autopsy of the extracted bar samples. The best corrosion performance was achieved by type 316L solid stainless steel (SS) dowel bars. Three types of stainless steel–clad bars also exhibited superior corrosion resistance. The epoxy-coated dowel bars performed well and behaved similarly to the SS bar types despite varying degrees of coating delamination and localized corrosion originating from some of the artificial coating defects.

The target audience of this report is State transportation departments, city and county engineers, pavement researchers, and consulting firms.

Cheryl Allen Richter, P.E., Ph.D.
Director, Office of Infrastructure
Research and Development

Notice

This document is disseminated under the sponsorship of the U.S. Department of Transportation (USDOT) in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in this document.

The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers’ names appear in this report only because they are considered essential to the objective of the document.

Quality Assurance Statement

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-15-079

2. Government Accession No.

 

3 Recipient's Catalog No.

 

4. Title and Subtitle

Laboratory Evaluation of Corrosion Resistance of Various Metallic Dowel Bars

5. Report Date

June 2018

6. Performing Organization Code

 

7. Author(s)

Seung-Kyoung Lee

8. Performing Organization Report No.

 

9. Performing Organization Name and Address

SK Lee & Associates, Inc.
Fairfax, VA 22030

Rutgers, The State University
100 Brett Road
Piscataway, NJ 08854

10. Work Unit No. (TRAIS)

Center for Advanced Infrastructure and Transportation (CAIT)

11. Contract or Grant No.

DTFH61-08-C-00005

12. Sponsoring Agency Name and Address

Office of Infrastructure Research and Development
Turner-Fairbank Highway Research Center
Federal Highway Administration
6300 Georgetown Pike
McLean, VA 22101-2296

13. Type of Report and Period Covered

Final report; January 2006–August 2015

14. Sponsoring Agency Code

HRDI-60

15. Supplementary Notes

The Federal Highway Administration Technical Contact is Donald Becker (HRDI-10) and the Contracting Officer’s Representative is R. Zobel (HRDI-30).

16. Abstract

This report presents corrosion study findings related to corrosion resistance of eight types of metallic dowel bars. The accelerated laboratory corrosion testing was performed using seven small-scale concrete slabs that simulated typical concrete pavements for 452 d of a modified Southern Exposure followed by a detailed autopsy of the extracted bar samples. The weekly Southern Exposure cycles consisted of a 4-d wetting cycle in 15 weight percent chloride solution at 75°F and a 3-d drying cycle at 100°F. The best corrosion performance was achieved by type 316L solid stainless steel (SS) dowel bars. Three types of stainless steel–clad (SC) bars also exhibited superior corrosion resistance. The epoxy-coated (EC) dowel bars performed well and behaved similarly to the SS bar types. However, the autopsied EC dowel bars revealed varying degrees of coating delamination, and localized corrosion originated from some of the artificial coating defects. Despite this problem, EC dowel bars were able to suppress corrosion activities because of the shielding role of the coating, even disbonded EC dowel bars, against corrosion current. As expected, the worst corrosion performance was observed with the uncoated carbon steel dowel bars. Most of them produced the corrosion-induced concrete cracks. The hot-dip galvanized and zinc-clad dowel bars are classified as the second worst performance group. Even though the zinc-coating layers performed well as the sacrificial cathodic protection systems for the bare steel exposed at the artificial defect sites, the consumption rates of the zinc mass were too excessive, leading to the premature depletion of the zinc layers in the areas with elevated chloride concentration. Therefore, these zinc-based dowel bars are recommended only for infrequently salted roadways and mild service conditions. For major roadways, where repairs and/or traffic disruption are not feasible, high grades of solid SS dowel bars are recommended, even though this means very high initial costs. Considering the unavailability of the SC bars and the good performance of EC dowel bars at a much lower price, it is recommended that high-quality EC dowel bars be continuously used in the majority of the major roadways subject to heavy deicing salts provided that damage touchups and stringent quality assurance/quality control practices are implemented in the field to minimize initial coating defects until they are buried in concrete.

17. Key Words

Corrosion, corrosion resistant metallic dowel bars, chloride threshold, corrosion initiation, corrosion propagation, autopsy, accelerated corrosion testing

18. Distribution Statement

No restrictions. This document is available to the public through the National Technical Information Service, Springfield, VA 22161.
http://www.ntis.gov

19. Security Classification
(of this report)

Unclassified

20. Security Classification
(of this page)

Unclassified

21. No. of Pages

92

22. Price

 

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

 

 

 

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