In order to verify the proposed heat and mass transfer models for the calculation method of timber drying time in our previous report, actual measurement of convective heat transfer coefficient and Biot number are needed. In this study, their values were obtained by timber drying tests with hinoki specimens of 50 mm square cross section and 900 mm length. The Biot number was approximated by a cubic curve with a moisture content variable, and was used for time calculations for the heating process (Process I) and bound water transfer process (Process III). An experimental convective heat transfer coefficient between timber surface and fluid in kiln was used for time calculation of the cooling process (Process IV). Timber drying times were obtained by drying tests with actual size specimens. In the range of initial moisture content lower than 70%, the calculated and experimental times were well correlated. It was confirmed that the proposed heat and mass transfer models were valid.

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In order to study fracturing of mortar which occurs on a wood and mortar exterior wall with an opening and the impact on each stapled joint of the accompanying separation of the mortar, three types of mortar separation patterns were hypothesized and the theoretical equation for a mortar exterior wall without an opening obtained in the previous report was used to analyze the stress distribution in each connecting part. To verify the analysis results and to confirm the behavior of the mortar, a lateral shear loading test of a mortar exterior wall with an opening was done. The results show that a fracture occurs vertically from the corner of the opening, that the separated mortar moves independently, and that the rotation center of the mortar varies according to the loading direction, shear deformation angle, and the part that separated. The results of analyzing the stress of each stapled joint based on the rotation behavior of the mortar obtained by the test clarified that if the center of rotation shifts, the breakage range of the stapled joints expands easily and the stress produced is remarkably small.

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We manufactured 5-ply sugi glulams with laminations treated with wood preservatives (ACQ, AZP) or untreated controls using two adhesive resins (PRF, API) and exposed them under outdoor conditions for 10 years. Shear strength of ACQ treated glulams decreased with exposure duration regardless of application of exterior finish or type of adhesive resin. The decrease was larger for PRF bonded than API bonded glulams. The decrease of shear strength for AZP treated and untreated glulam was less than for ACQ treatment. Shear strength of glulams with exterior finish repainted periodically hardly decreased after 10 years of exposure. Shear strength of glulam without wood preservatives or exterior finish decreased because of wood decay. However, for analysis omitting decayed pieces, shear strength of those glulams hardly decreased. Shear strength of pieces obtained from the middle part of the width direction of glulam tend to show higher values than pieces from either outer sides.

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To degrade pruned fruit-tree branches rapidly, microbial preparations were prepared from the mycelia of Pycnoporus coccineus. A powdered microbial preparation gave inferior mycelial growth. Mycelial growth was observed from liquid microbial preparations for 5 months at 20 and 35°C. Decrease in both weight and basic specific gravity of sterilized branches inoculated with liquid and solid microbial preparations was significantly less than that of controls. The result was the same for unsterilized branches inoculated with a solid microbial preparation. Moreover, the weight loss of pear branches crushed to 5.5-10 mm and inoculated with a solid microbial preparation was greater than that of branches crushed to 10-50 mm. In terms of degradation ability, it was clarified that a solid microbial preparation from mycelia of Pycnoporus coccineus degrades pruned branches rapidly.

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Wood is regarded as an Environmentally Friendly material. However, it is difficult to show quantitative evidence. Therefore we conducted a life cycle assessment of domestic logs. As a result of this analysis, it was estimated that to produce 1 m³ of domestic logs caused the emission of 11.1 kg of CO₂ and had an environmental impact of 70.6 Yen. Besides, for reducing the environmental impact from domestic log production it is important to improve the logging processes such as thinning and final cutting. Among them, we could reduce the impact more if high-performance forest machinery was used more efficiently in the logging process.

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In this study, we investigated the mechanical properties and durability of particleboards made of short-rotation willow coppices: KKD clone and HB471 clone (Salix pet-susu), SEN clone (S. sachalinensis) and FXM clone (S. pseudolinearis). These four willow clones were harvested after a single year of cultivation. The mechanical properties, termite resistance, and fungal resistance of the willow particleboards were evaluated by comparison with cedar sapwood and cedar heartwood particleboards. Willow particleboards of the four clones had the same mechanical performance. They showed lower modulus of elasticity (MOE) and modulus of rupture (MOR), but also the same internal bonding strength (IB) and thickness swelling on water absorption (TS) compared with the cedar boards. Termite resistance of the particleboards was assessed by feeding tests with Formosan subterranean termites and Japanese subterranean termites. The SEN clone particleboard showed high mortality against the Formosan subterranean termites, but the other three clones showed low termite resistance, the same as the cedar sapwood. Fungal resistance of the particleboards was assessed by decay tests with white-rot fungus and with brown-rot fungus. All four willow particleboards showed lower fungal resistance than the cedar sapwood particleboard.

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To examine the durability of plywood used in actual houses, we investigated the bending and panel shear properties of floor sheathing plywood extracted from eight houses in Hokkaido, all of which were classified as Type 1 plywood according to the Japanese agricultural standard (JAS). Furthermore, we examined the strength of new control plywood after accelerated aging treatments, and we compared it with the deterioration of actual use. Both bending properties and panel shear properties of plywood used in actual houses almost exceeded the JAS requirements. We estimated the retention of these properties of the used plywood on the basis of the properties of the new control plywood. The retention of strength was lower than that of elasticity, and this tendency agreed with the results of accelerated aging tests of the control plywood. By comparing the relation between boiling cycles or durations of use and retention of these properties, we could calculate the durations of use that causes strength deterioration equal to one boiling cycle.

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