Studying the spatio-temporal dynamics of wood decay with X-ray CT scanning

Bio-based building materials are susceptible to degradation by decay fungi when exposed to favourable conditions for fungal growth. The risk of decay depends on both the environmental conditions and material resistance. Although durability data is available for solid wood, standard tests mainly focus on mass loss assessment after a fixed degradation period. In-depth knowledge on time-dependent decay patterns is lacking, yet could prove relevant for optimisations of the structural design of engineered wood products to increase their service life. Here, a novel X-ray CT scanning set-up and analysis pipeline for non-destructive assessment of the influence of material structure on temporal decay patterns under laboratory conditions is presented. Wood specimens that were severely degraded showed a pattern in which the density decreased substantially after 2 weeks, due to wood mass being metabolised into mycelium, carbon dioxide and water. The influence of various anatomical features, such as the vessel orientation and the number of growth rings, on wood degradation patterns was demonstrated. This approach is a starting point for further in-depth research on the influence of material structure on decay. The method is especially interesting to assess the efficacy of structural modification strategies that are expected to inhibit decay or enhance service life.