Evaluating the Corrosiveness of Southern Pine Treated with Several Wood Preservatives Using Electrochemical Techniques

Chromated copper arsenate (CCA), the most widely used wood preservative of the past 50 years, has been replaced for most uses with alkaline-copper systems such as alkaline copper quaternary (ACQ), copper azole (CuAz) and micronized copper quaternary (MCQ).  Preliminary research using high-temperature, high-humidity environments have shown that these wood preservatives are more corrosive than CCA, although it is unclear how the results of these extreme tests correlate to performance at temperatures and humidities seen in-service.  Recently, the authors developed an electrochemical method for rapid determination of the corrosion rate for fasteners in water extracts of treated wood.  The authors have previously demonstrated good correlation between the electrochemical-extract test and exposure tests of fasteners in ACQ treated Southern pine.  This work uses the electrochemical-extract method to examine corrosion of carbon steel and galvanized steel on untreated southern pine, as well as southern pine treated with five different wood preservatives