Abstract

This study explored the biological durability of Pinus radiata wood treated with copper nanoparticles (CuNPs) and a commercial micronized copper (M) formulation. The internal structural integrity of the wood was evaluated using micro-computed tomography. Sapwood specimens were pressure-impregnated with CuNP (0.31% w/w) or M (0.56% w/w), achieving average copper retentions of 0.98 and 1.05 kg m(-3), respectively. Biological resistance was assessed through standardized soil-block decay tests using Gloeophyllum trabeum, Coniophora puteana, Trametes versicolor, and Irpex lacteus, and an 8-week no-choice subterranean termite assay with Reticulitermes flavipes. After 12 weeks of fungal exposure, treated specimens exhibited markedly lower mass losses (<4.5% for CuNP and <1% for M) than untreated controls (11-25%). Chemical composition analyses confirmed the reduced degradation of cellulose, hemicellulose, and lignin in the treated wood. Termite tests showed mass losses of 9.0% for M and 5.7% for CuNP; notably, CuNP-treated blocks caused complete termite mortality. High-resolution micro-computed tomography provided 3D evidence of preserved microstructures and revealed distinct preservative distribution patterns associated with each formulation. Overall, this study provides an integrated structural and biological evaluation demonstrating that both CuNP and M treatments enhance the durability of P. radiata, with CuNP offering promising performance, supported by micro-CT insights.