Synthesis of Published and Unpublished Corrosion Data From Long Term Tests of Fasteners Embedded in Wood: Calculation of Corrosion Rates and the Effect of Corrosion on Lateral Joint Strength

In the past 5 years, several accelerated test methods have been developed to measure the corrosion of metals in contact with wood.  To compare these new test methods, it is desirable to contrast these results  against the results of long term exposure tests.  While there have been several long-term exposure tests performed on metals in treated wood, the data from these studies could not be used as a baseline as the amount corrosion was presented as percent mass loss instead of a true corrosion rate because the surface areas of the fasteners were unknown.  In this work, the archives of the US Forest Products laboratory were examined for additional information on two key corrosion studies.  In the process of obtaining the original laboratory notebooks, two additional reports were found that had never been published.  This paper reports the unpublished details of the two published studies as well as the results of the unpublished studies so that the data can be used when designing for corrosion of metals in wood.  Where possible, the composition of the preservatives are reported from the original laboratory notebooks.  In all cases, the percent mass loss data are presented in terms of a true corrosion rate by calculating the surface areas of the fasteners.  The second part of this paper uses the long term corrosion rates to calculate the reduction in capacity of the joint using the yield theory equations from the National Design Specification for Wood Construction.