Partner und Internationale Organisationen
(Englisch)
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A, B, CZ, DK, FIN, F, D, GR, H, IRL, I, NL; N, PL, P, SI, E, S, CH, GB
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Abstract
(Englisch)
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Within a project of Prof. Dr L. Sandoz of EPFL (Swiss Federal Institute of Technology in Lausanne (IBOIS), a part project has focused on the influence of the heat treatment on the durability of spruce against wood destroying fun-gi. The heat treatment has resulted in a higher durability of the wood against destroying fungi and to a lower vis-cosity of the cellulose. Natural weathering tends to have a negative influence on the durability of thermically trea-ted wood. The heat treatement has no influence on disfiguring fungi. After a short weathering time the wooden façades are covered with blue stain. This report will be published by EPFL.Within the other part project, the department Biology of EMPA has effected biodegradation tests with diverse spe-cies of wood destroying fungi on spruce and beech wood samples for P. Niemz of the Swiss Federal Institute of Technology in Zurich (ETHZ) (Professorship for Wood Sciences). Subsequently, Mr St. Hebeisen has studied, for his diploma, the influence of fungi after different incubation times by measuring of sound velocity and characte-ristic frequency of the wood. Untreated beech and spruce samples have been exposed during 0, 8, 16, 24 et 32 weeks, at 22 °C and optimal humidity conditions, to the attack of wood destroying fungi. Due to a fungal attack during 24 weeks by Coriolus versicolor, the weight of the beech samples has been reduced - primarily as a consequence of the biodegradation of lignin (white rot) - by 37%, the raw density by 41%, the sound velocity by 35%, the inherent frequency by 70%, the bending strength by 70%, the modulus of elasticity by 52% and the material has become brittle. After an attack by Gloeophyllum trabeum during 24 weeks, the weight of the spruce samples has been reduced - primarily as a consequence of the biodegradation of cellulose (brown rot) - by 27%, the raw density by 16%, the sound velocity by 22%, the inherent frequency by 27%, the bending strength by 85%, the modulus of elasticity by 82% and the material has become brittle. Some further investigations are running in fieldtest in soil and in the laboratory with wood destroying insects. This tests need more then two years, longer then the duration of this project.
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