Due to increased environmental awareness, large demands for structural timber and shrinking natural stands, much attention is paid to finding new methods for the production of quality wood, also in structural use. Wood densification has had a long tradition, and it is again coming into focus because of the growing importance of renewable land resources, also of plantation wood. Densified wood has better mechanical properties than uncompressed wood of the same species. The thesis tries to verify if the densified plantation timber could be used for construction purposes also in the case of exposure to biological influence. Compressed Douglas fir and hybrid poplar wood were used and treated with thermo-hydro-mechanical method of densification by 3 different procedures of compression, varing according to the temperature and humidity in the chamber during the mechanical compression of samples: 170 °C in the transient conditions of water vapor (TS); 170 °C with saturated water vapor (SS); 170 °C with saturated water vapor (SS), and by further heating to 200 °C (SS+PHT). Wood specimens were exposed to Gloeophyllum trabeum and Trametes versicolor species for a period of 2, 4, 6 and 8 weeks, and the changes in dimension, colour, weight loss, mechanical properties and chemical characteristics of wood were observed. The results showed that in the studied processes the densification temperature used was too low and the duration of exposure to heat was too short for densified wood to have an improved resistance to fungi. Therefore, densified wood without an adequate protection against biological degradation is not suitable for structural use.
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