The durability of wood in exterior use is limited by to climatic factors and wood deteriorating organisms. The natural durability of the Nordic wood species is generally regarded as low, and for e.g. decking and use in soil contact wood protection is needed. Within the last years, new non-biocidal treatments, like wood modification systems, have been developed to improve the biological resistance of wood. For information about the decay resistance of untreated and modified wood, natural outside exposure is necessary. European standard EN 252 is the main field test method for use class 4. In use class 3 the need of new or improved test setups has been put forward. Traditionally evaluation of field trials has mainly been based on visual evaluation and pick-test. However, to get in depth knowledge about: 1) different field trial methods and 2) fungal colonization of new wood protection systems, additional assessment methods can be used. Hence, comparative studies are needed.
In this study, two outdoor test-procedures, the block-test for use class 3 and the EN 252 standard for use class 4, were used as model methods for comparison between different decay assessment methods. Untreated Scots pine (Pinus sylvestris) samples were exposed in field for 4 years (2004 to 2008). A range of different methods were used to evaluate decay. The following methods for detecting early decay gave significant correlation with mass loss: MOEdyn, chitin- and ergosterol assays, lignin content using TGA and EMC. For severe decay, only lignin and cellulose gave significant correlation with mass loss.
Keywords: Assessment methods, block-test, EN 252, Scots pine sapwood, wood decay
Authors
Friese F.
Wood Biology and Wood Products, Burckhardt-Institute, Georg-August-University, Göttingen, Germany
Larnøy E.
Norwegian Forest and Landscape Institute, Ås, Norway
Alfredsen G.
Norwegian Forest and Landscape Institute, Ås, Norway
Pfeffer A.
Wood Biology and Wood Products, Burckhardt-Institute, Georg-August-University, Göttingen, Germany
Militz H.
Wood Biology and Wood Products, Burckhardt-Institute, Georg-August-University, Göttingen, Germany
Login to download the PDF