Evaluation of Wood Species and Preservatives for Use in Wisconsin Highway Sign Posts

The Wisconsin Department of Transportation (WisDOT) uses wooden posts to support many types of signs along state highways. WisDOT currently uses red pine or Southern Pine posts treated with chromated copper arsenate (CCA) and has generally experienced satisfactory performance and service life. However, there are some areas of concern, as well as potential opportunities for diversifying the wood species and preservatives used. Warp is sometimes a problem with the current pine posts, and increased use of locally sourced wood species for the sign posts could decrease transportation costs and potentially benefit Wisconsin industries. Although CCA is a highly effective preservative, it may not be the optimum treatment for alternative wood species. This study reviewed the characteristics of alternative wood species and wood preservatives and evaluated their potential for use in Wisconsin highway sign posts. The evaluation concluded that WisDOT’s current practice of using red pine or Southern Pine posts treated with CCA is logical and may be the optimum combination of wood species and preservatives currently available. Red pine and Southern Pine are readily available and relatively strong compared with many other softwood species. Red pine is also an important commercial resource for Wisconsin and the upper Midwest. Other Wisconsin species to consider include eastern white pine and soft maples. However, strength may be a concern with eastern white pine, whereas cost may be a concern with soft maples. CCA is an effective preservative, readily treats red pine and Southern Pine, and is compatible with aluminum signs. Copper naphthenate in oil solvent appears to be one of the most logical alternatives to CCA, and would be a strong candidate for treatment of hardwoods. Copper naphthenate is non-corrosive to aluminum and would avoid warp associated with re-drying after treatment with water-based preservatives. WisDOT may want to consider purchasing a small volume of copper naphthenate-treated posts to evaluate the handling characteristics of this oil-based preservative.

[1]  J. Watkins,et al.  Treatability of U.S. wood species with pigment-emulsified creosote , 2000 .

[2]  Stan Lebow,et al.  Comparison of wood preservatives in stake tests : 2011 progress report , 2011 .

[3]  Samuel J. Record,et al.  The mechanical properties of wood , 1914 .

[4]  William B. Smith.  Treatability of several northeastern species with chromated copper arsenate wood preservative , 1986 .

[5]  A. Baker,et al.  Corrosion of nails in CCA- and ACA-treated wood in two environments , 1992 .

[6]  D. Binkley,et al.  Sustaining Aspen in Western Landscapes: Symposium Proceedings , 2001 .

[7]  M. Rohwerder,et al.  Corrosion of Zinc and Zn-Mg Alloys with Varying Microstructures and Magnesium Contents , 2014 .

[8]  D. R. Rammer,et al.  Optical method for measuring the surface area of a threaded fastener , 2009 .

[9]  D. Knotková‐Čermáková,et al.  Corrosive Effect of Plastics, Rubber and Wood on Metals in Confined Spaces , 1971 .

[10]  J. Wilson.  ALUMINUM SIGN CORROSION INVESTIGATION , 2004 .

[11]  Samuel V. Glass,et al.  Moisture relations and physical properties of wood , 2010 .

[12]  Y. Miyata,et al.  Galvanic Series of Metals Conventionally Used in Tap Water With and Without Flow and Its Comparison to That in Seawater , 2011 .

[13]  G. Kear,et al.  Weight loss studies of fastener materials corrosion in contact with timbers treated with copper azole and alkaline copper quaternary compounds , 2009 .

[14]  C. McIntyre.  Comparison of micronized copper particle sizes. , 2010 .

[15]  Zinc Alloy Coated Steel Sheet,et al.  Proceedings : 4th International Conference on Zinc and Zinc Alloy Coated Steel Sheet : GALVATECH '98 : September 20-23, 1998, Makuhari, Chiba, Japan , 1998 .

[16]  R. A. Legault,et al.  Kinetics of the Atmospheric Corrosion of Low-Alloy Steels in an Industrial Environment , 1975 .

[17]  David A Webb,et al.  Creosote posts 50 years later : / final inspection of the 1958 cooperative test after 50 years of exposure as a ground contact preservative , 2009 .

[18]  Donald J. Miller.  Service life of treated and untreated fence posts : 1985 post-farm report , 1958 .

[19]  P. Koch.  Utilization of hardwoods growing on southern pine sites / Peter Koch. , 1985 .

[20]  J. O. Blew,et al.  SERVICE RECORDS ON TREATED AND UNTREATED FENCE POSTS , 1964 .

[21]  Dominique Derome,et al.  Combining hygrothermal and corrosion models to predict corrosion of metal fasteners embedded in wood , 2011 .

[22]  T. Mcconnell,et al.  Preservative-Treated Wood: A Sustainable Consumer Choice , 2011 .

[23]  Robert J. Ross,et al.  Wood handbook : wood as an engineering material , 2010 .

[24]  W. Simpson.  Dry kiln operator's manual , 1991 .

[25]  Donald S. Stone,et al.  Exposure testing of fasteners in preservative treated wood: Gravimetric corrosion rates and corrosion product analyses , 2010 .

[26]  D. Stone,et al.  Corrosion of metals in wood: Comparing the results of a rapid test method with long-term exposure tests across six wood treatments , 2011 .

[28]  D. L. Lynch,et al.  The Effect of Aspen Wood Characteristics and Properties on Utilization , 2001 .

[29]  Craig R. McIntyre,et al.  Copper-Based Wood Preservatives A Comprehensive Review of Copper-Based Wood Preservatives , 2008 .

[30]  Analytical Determination of the Surface Area of a Threaded Fastener , 2008 .

[31]  Rebecca E. Ibach,et al.  WOOD PRESERVATION. , 1927, Science.

[32]  S. Lebow,et al.  Treatability of SPF Framing Lumber with CCA and Borate Preservatives , 2007 .

[33]  Joseph Oscar Blew.  Treating wood by the cold-soaking method , 1961 .

[34]  D. Markstrom,et al.  Service life of treated and untreated Black Hills ponderosa pine fenceposts , 1992 .

[35]  Rubin Shmulsky.  Dimensional stabilization of pine four-by-fours via restraint drying , 2006 .

[36]  S. Lebow,et al.  Treatability of underutilized northeastern species with CCA and alternative wood preservatives , 2005 .

[37]  Peter E. Laks,et al.  FIELD PERFORMANCE OF NEW WOOD PRESERVATIVE SYSTEMS IN SECONDARY TIMBER SPECIES , 1996 .

[38]  J. O. Blew,et al.  Comparison of wood preservatives in Mississippi post study (1953 and 1954 Progress Reports). , 1953 .

[39]  B. Dawson-Andoh,et al.  The durability of yellow-poplar and red maple treated with ACQ-B , 2001 .

[40]  Samuel L. Zelinka,et al.  Uncertainties in Corrosion Rate Measurements of Fasteners Exposed to Treated Wood at 100 % Relative Humidity , 2007 .

[41]  P. Cooper.  Pressure-preservative treatment of Poplar lumber , 1976 .

[42]  Lee R. Gjovik,et al.  Service Records on Treated and Untreated Fenceposts. , 1975 .

[43]  Douglas R. Rammer,et al.  Corrosion Rates of Fasteners in Treated Wood Exposed to 100% Relative Humidity , 2009 .

[44]  L. R. Gjovik,et al.  Comparison of Wood Preservatives in Mississippi Post Study: 1973 Progress Report. , 1969 .

[45]  Peter Koch,et al.  Serrated kiln sticks and top load substantially reduce warp in southern pine studs dried at 240°F , 1974 .