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
some of 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.
Keywords: wood, fastener, polarization resistance, steel, galvanized steel, alkaline copper
quaternary (ACQ), chromated copper arsenate (CCA)