Technical Report Documentation Page 1. Report No. 2. Government Accession No 3. Recipient’s Catalog No 4. Title and Subtitle 5. Report Date Evaluation of Wood Species and Preservatives for WisDOT Sign Posts October 2013 6. Performing Organization Code 7. Authors 8. Performing Organization Report No. Stan Lebow, Robert Ross, Sam Zelinka, and Carol Clausen 9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) USDA, Forest Service, Forest Products Laboratory One Gifford Pinchot Drive 11. Contract or Grant No. Madison, WI 53726 WisDOT SPR# 0092-13-15 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered Wisconsin Department of Transportation Division of Business Management 14. Sponsoring Agency Code Research & Library Unit 4802 Sheboygan Ave. Rm 104 Madison, WI 53707 15. Supplementary Notes 16. Abstract The Wisconsin Department of Transportation (WisDOT) uses preservative-treated wood posts for much of the signage along state highways because wood is relatively inexpensive, easy to install, and has the necessary strength properties to tolerate typical Wisconsin wind loads. Although WisDOT’s experience with wood sign posts has been generally positive, there are some areas of concern, as well as opportunities for diversifying the wood species and preservatives used. WisDOT and the USDA, Forest Products Laboratory began a collaborative project to address those concerns and opportunities. This report presents the findings of the comprehensive literature review. 17. Key Words 18. Distribution Statement Wood products, wood preservatives, sign supports, posts, Wisconsin Department of Transportation No restriction. This document is available to the public through the National Technical Information Service 5285 Port Royal Road Springfield VA 22161 18. Security Classif.(of this report) 19. Security Classif. (of this page) 20. No. of Pages 21. Price Unclassified Unclassified 86 Form DOT F 1700.7 (8-72) Reproduction of completed page authorized 1 DISCLAIMER This research was funded by the Wisconsin Department of Transportation and the Federal Highway Administration under Project 0092-13-15. 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 views of the Wisconsin Department of Transportation or the Federal Highway Administration at the time of publication. This document is disseminated under the sponsorship of the Department of Transportation in the interest of information exchange. The United States Government assumes no liability for its contents or use thereof. This report does not constitute a standard, specification or regulation. The United States Government does not endorse products or manufacturers. Trade and manufacturers’ names appear in this report only because they are considered essential to the object of the document. 2 3 Evaluation of Wood Species and Preservatives for WisDOT Sign Posts Comprehensive Literature Review Stan Lebow, Robert Ross, Sam Zelinka, Carol Clausen USDA, Forest Service, Forest Products Laboratory Prepared for: Wisconsin Department of Transportation October, 2013 4 Contents DISCLAIMER ...................................................................................................................................................... 2 Introduction .................................................................................................................................................. 8 Wisconsin’s Current Sign Post Standard Specifications ............................................................................ 8 Wood Species Considerations ................................................................................................................... 8 Wood Preservative Considerations .......................................................................................................... 9 Research Approach ................................................................................................................................. 10 Wood Preservative Background ................................................................................................................. 10 Remedial, in-place, field-applied, supplemental or non-pressure preservatives ............................... 10 Pressure treatment preservatives and pressure-treated wood ......................................................... 11 AWPA vs ICC-ES and AASHTO Preservative Listings ................................................................................ 11 Evaluating Preservative Efficacy ............................................................................................................. 12 Stake and post field tests .................................................................................................................... 12 Role of Solvent Characteristics in Durability ........................................................................................... 13 Corrosion testing ..................................................................................................................................... 13 AWPA Use Category System ................................................................................................................... 14 Wood Preservative Characteristics ............................................................................................................. 15 The Role of Copper in Wood Preservatives ............................................................................................ 15 Current Ground-contact Preservatives ................................................................................................... 16 Acid Copper Chromate (ACC) .............................................................................................................. 16 Ammoniacal Copper Quat (ACQ-B) ..................................................................................................... 18 Alkaline copper quat, (ACQ Types A, D and C and ESR-1980) ............................................................. 18 Ammoniacal Copper Zinc Arsenate (ACZA, previously ACA)............................................................... 20 Chromated Copper Arsenate (CCA) .................................................................................................... 21 Coal-tar creosote................................................................................................................................. 21 Copper Azole (CA-B and CA-C, ESR-1721, ESR-2240) .......................................................................... 23 Copper Naphthenate (CuN) ................................................................................................................ 24 KDS ...................................................................................................................................................... 25 Pentachlorophenol.............................................................................................................................. 25 Other Preservatives of Interest ............................................................................................................... 26 Copper Xyligen (CX-A) ......................................................................................................................... 26 Copper Borate (Cu-Bor) ...................................................................................................................... 26 Copper-8-quinolinolate (Cu8 and Cu8-W) .......................................................................................... 27 5 3-Iodo-2-proponyl carbamate (IPBC) .................................................................................................. 28 Didecyl dimethyl ammonium chloride (DDAC) and Alkyl benzyl ammonium chloride (BAC) ............ 29 Isothiazolone, 4,5-dichloro-2-N-octyl-4-isothiazolin-3-one (DCOI) .................................................... 29 Tebuconazole (TEB) and Propiconazole (PPZ) .................................................................................... 30 Chlorothalonil (CTL) ............................................................................................................................ 30 Borates ................................................................................................................................................ 31 Insecticidal Additives .......................................................................................................................... 31 Combinations of Non-metallic Preservatives ............................................................................................. 32 EL2: DCOI and Imidacloprid ................................................................................................................ 32 PTI: Propiconazole-Tebuconazole-Imidacloprid ................................................................................. 32 DDAC/IPBC Combinations (NP-1 and NP-1 Variations) ....................................................................... 32 IPBC/PPZ/TEB (3-Iodo-2-proponyl carbamate/Propiconazole/Tebuconazole) ................................. 33 IPBC/Permethrin (IPBC/PER) ............................................................................................................... 33 Corrosion aspects of selecting preservatives for sign posts ......................................................................