MOKUZAI HOZON (Wood Protection)

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The insulation panels developed in this study are composed of wood shavings compressed into a mat with a density of 110 kg/m³ without any binder. This mat is lapped with plastic film that works as a damp proof course. This paper describes fire tests conducted with a full-scale-thick wooden frame wall that was sandwiched with wood-fiber cement board and plasterboard. The test wall was filled with 100-mm-thick wood shaving insulation panels or fiberglass insulators, or a hollow. These three types of wall were examined for heat shielding effect and cross section loss of wood column (105mm by105mm). The results revealed that the test wall filled with our insulation panels had a higher heat shielding performance than other walls. This is because charring of wood shavings generates water and some of it remains near the rear surface of the panels due to an existence of plastic film, and consequently, the water consumes vaporization energy and resulted in keeping a temperature lower than of around 100°C. The heat shielding performance was found to have a quality equivalent to the 60-minute quasi-fireproof performance stipulated in the Building Standard Law of Japan. Furthermore, our insulation panel was found to provide a wall less cross section loss of wood column than a wall filling with fiberglass. This suggests that wood shaving insulation panels are superior to fiberglass in terms of structural safety by fire as well as heat shielding performance.

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Biological resistance and hygroscopicity of the wood treated by heat (140 - 240°C) for 24 hours under nitrogen atmosphere were investigated.
Fungal resistance test was carried out as described in JIS K 1571: 2004. Mass loss of heattreated sugi (Cryptomeria japonica D. Don) sapwood subjected by Fomitopsis palustris - FFPRI 0507 and Trametes versicolor - FFPRI 1030 decreased, as the heating temperature increased. Especially, the wood treated at 220°C and 240°C showed high resistance against fungi. Similar result was also shown by the fungus cellar (soil-bed) test. But the termite resistance of the wood treated at 240°C was not high in the laboratory.
Field stake tests were also carried out as described in JIS K 1571: 2004. Resistance against fungi and termite in the field increased by heat treatments.
Hygroscopicity of the heat-treated wood decreased as the heating temperature increased. It was considered that decrease of hygroscopicity had some effect on increase of biological resistance.

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