The article presents the results regarding the evolution of the temperature field in spruce wood (Picea abies L.) during freezing at two different freezing rates: -100C/h (rapid freezing) and -10C/h (slow freezing) and then during thawing at +50C, +30°C, +50°C temperature. This approach aimed at simulating the temperature variations which occur inside timber during open air storage in winter in two situations (sudden vs. gradual drop of temperature), and then when the timber enters the drying kiln, depending on the temperature applied in the initial heating phase. The results clearly show that the freezing rate significantly influences the thawing time and speed, which increase by 13-17% in the case of slowly frozen wood (at -10C/min) compared to rapidly frozen wood (at -100C/min). It was also established that the optimum temperature in the heating-up phase when drying frozen spruce is 300C instead of the usual 50 degC. This value leads to much better drying uniformity without significantly prolonging the drying time.

The effect of density on the natural resistance of ten selected Nigerian wood species to subterranean termites was investigated. Wood samples obtained from mixed-conversion boards were used such that the samples contained both sapwood and the heartwood. They were sawn to 35×35×450mm stake and dried at 103 ±20C till a constant weight was achieved. Density of the selected wood species was determined. Based on the observed average density, the wood species were classified into high, medium or low density. Graveyard test method was used to assess the natural resistance of the samples on a site dominated by Macrotermes sybhylinus, a family of subterranean termites. Weekly visual observations of the stakes were taken as specified in ASTM D3345-80 Standards for 24 weeks. The wood samples were withdrawn at the 24th week of exposure to termites and weight loss due to termites’ attack was estimated. Result obtained showed the relationship between wood density, weight loss and the ASTM ratings. A strong but negative correlation (R2= -0.70) existed between weight loss and wood density while a strong positive correlation (R2=0.83) existed between ASTM values and wood density. These results indicated that wood species in the high density class had a better resistance to termites’ attack. The influence of mixed conversion on the resistance of wood species to subterranean termites was also reported, since it is the most common method of conversion in the Nigerian sawmills. The sapwood of high density species are not durable as revealed in the study thus the preservative treatment is imperative for long service-life.

Composite materials for liningst and wall filler made of hemp hurds and mineral binders represent a gain in recovery of mineral binders and use of represent lignocellulosic fiber resulted after processing. This paper aims to establish the optimum percentual range of hemp hurds that can be embedded in ceramic mass, which is able to support in various stages, the physical and dimensional integrity, manipulation, transport and during sanding resistance, the remaining viable recipes being the ones that successfully pass this preliminary test. It is expected for these samples to have comparable thermal and acoustic properties with similar industrial products, currently manufactured, which gives thepractical applicability of these composites.

An overview on the mechanical and physical properties of cross laminated timber (solid wood panels) in the building industry and its use in timber construction is presented. Structure-property relations for solid wood based materials are discussed. Important properties, such as strength,sorption, diffusion, thermal conductivity in relation to the board structure are presented. By varying the structure, the properties can be optimized over a wide range. The focus of this publication lies on experimental works performed by Swiss researchers at the ETH Zürich.

Bonding technology is one of the key technologies for producing wood-based materials. Surface quality of solid wood products is one of the most important properties influencing further manufacturing processes such as finishing or strength of adhesive joint. The aim of this study was to determine the influence of sanding with different grit sizes on bonding strength and some mechanical properties of poplar and beech plywood. For this reason, 2mm thick rotary cut veneers obtained from freshly cut (not treated) poplar (Populus deltoides I- 77/51) and beech (Fagus orientalis) logs were used as material. The surfaces of some veneers were sanded with 80 and 180 grit size. Three-layerplywood were produced from sanded and nonsanded veneers using phenol formaldehyde glue resins to evaluate the effects of sanding some mechanical properties of plywood. Rz roughness parameter was measured to evaluate surface roughness of veneer according to DIN 4768. Bonding and bending strength values of plywood manufactured from sanded and non-sanded veneers varied depending on wood species and grit size. Bonding strength values of plywood increased with decreasing surface roughness values of veneers both of two wood species.