Corrosion Rates of Fasteners in Treated Wood Exposed to 100% Relative Humidity

Abstract

In the past, gravimetric corrosion data for fasteners exposed to treated wood has been reported as a percent weight loss. Although percent weight loss is a valid measure of corrosion for comparing identical fasteners, it can distort the corrosion performance of fasteners with different geometries and densities. This report reevaluates a key report on the corrosiveness of wood treated with chromated copper arsenate (CCA) and ammoniacal copper arsenate (ACA) and converts the previous data into corrosion rates. In addition, similar experiments were run in wood treated with alkaline copper quaternary (ACQ). Comparison of the corrosion rates reveals ACQ treated wood is more corrosive than CCA treated wood for every metal. The corrosion rate of aluminum was found to be lower than both hot-dip galvanized steel and electroplated galvanized steel in ACQ, ACA, and CCA treated wood. In ACA and ACQ treated wood, the electroplated galvanized fastener had a lower corrosion rate than the hot-dip galvanized fastener.