Monitoring of Beech Glued Laminated Timber and Delamination Resistance of Beech Finger-Joints in Varying Ambient Climates

In this study, varying ambient climates were simulated in a test building by changing temperature and relative humidity. Beech glued laminated timber (glulam, Fagus sylvatica, L.) was freshly installed in the test building and monitoring of the change in wood moisture content of the glulam resulting from the variations in climate was carried out. Subsequently, finger-jointed beech specimens were exposed to the variations in relative humidity measured in the course of the monitoring experiment on a laboratory scale, and thus an alternating climate regime was derived from the conditions in the test building. Its influence on the delamination of the finger-joints was evaluated. In addition, it was examined whether beech finger-joints using commercial adhesive systems fulfil the normative requirements for delamination resistance according to EN 301 (2018) and whether different bonding-wood moisture levels have an effect on the delamination of the finger-joints. In the context of the monitoring experiment, there was a clear moisture gradient in the beech glulam between the inner and near-surface wood. The applied adhesive systems showed almost the same delamination resistance after variation of relative humidity. The normative requirements were met by all PRF-bonded and by most PUR-bonded beech finger-joints with higher bonding wood moisture content.

Wood Moisture-Content Measurement Accuracy of Impregnated and Nonimpregnated Wood

The influence of the impregnation process of pine wood (Pinus sylvestris L.) samples on the electrical resistance changes and the moisture-content measurement accuracy is presented in this paper. In this study, the resistances of impregnated and nonimpregnated green pine timber harvested from northern Poland were compared. An impregnation method based on a vacuum-pressure chamber was used. Copper salts were applied as the impregnated solutions. The obtained results of the electrical resistance comparison showed a dependence of wood resistance on the moisture content. Higher conductivity occurred in impregnated wood samples filled with copper salt compared with wood samples without impregnation. Noticeable differences in the electrical resistance values were observed when the wood moisture content was significantly above the Fibre Saturation Point (FSP).

DEVELOPMENT OF WOOD GRINDING. 3. FURTHER TESTING OF GRINDING MODELS

"The study is the continuation of a sequence of works devoted to describing the mechanisms occurring during stone grinding of wood. This part was aimed at further testing of pressurised grinding of spruce wood, which was conducted under controlled laboratory conditions. Testing of the developed theoretical model for power ratio (Pc/Pt) versus energy specific production (Ġw/Pt) produced linears for data representing constant wood moisture content. However, the linears showed almost identical results for fresh woods, and also for drier wood, e.g. wood containing saturated fibres and air-dried wood, although one would expect some differences due to the widely varying constant moisture, from 65% to 15% moisture content. Simplification of the model resulted in (cw + X cm) ΔTp-w ≈ Pt / Ġw, and it led to specific linears, when the members as such were correlated between themselves at several constant wood moisture contents. The results were briefly as follows. Increasing wood feed rate – 0.7, 1.0 and 1.3 mm/s – decreased the specific energy requirement, while increased stone surface speed – 20 and 30 m/s – increased it. The left-hand member or the “X-factor” as named in this context, correlated with the right-hand member or the specific energy requirement and resulted in declining linears. The lower the wood moisture content – 65, 58, 44, 28 and 15% – the smaller was the linear declination, and also the difference due to stone surface speed. The application of an energy balance could be useful in searching for a working wood grinding model. Such a model would enable critical examination of wood grinding conditions. Also, it would help understanding the mechanism of various factors, such as grinding parameters, wood properties and stone burr and sharpness. It seems that there are factors that are not known well enough for further development of grinding. Shower water flow and temperature affect the stone surface temperature as known, but their significance for the energy balance or grinding mechanism are not known. Also, the thin film of pulp slurry between the stone surface and the heat activated wood layer is evidently a significant factor that is connected to the local energy transfer. "

Pengaruh Waktu Kupas dan Volume Kayu Terhadap Produktivitas dan Biaya Pengupasan Kulit Kayu Hutan Alam

Debarking is the activities in the loading point after bucking. The purpose of debarking is to clean wood from bark and reduce the wood moisture content to be easier for further handling. The research method was carried out by selecting the location of 2 loading points where debarking was done, measuring the debarking time and the log volume, and then analyzing the effect of debarking time and log volume on the productivity of debarking with multiple regression analysis. The results showed that: 1) The average debarking produkctivity in loading point 1 was 21.12 m3/hr an average debarking time of 25.49 minutes and log volume of 9.16 m3; 2) The average productivity of debarking in the second loading point was 20.77 m3/hr with an average debarking time of 19.45 minutes and a log volume of 6.81 m3; 3)The average of debarking cost at loading point #1 is lower than at loading point#2; 4) The resulting regression equation model is Y = 20,931.001 – 49,516.314 X1 + 2.324 X2; and 5)The log volume is significant to debarking productivity, while the debarking time is negative

Moisture distribution over tree trunk cross-section in bilberry spruce forests

The article considers the change in the moisture content in the wood along the cross-section of spruce trunks, it also analyzes the influence of the trees age and the diameter of the trunk on the wood moisture content. The research was carried out in the Arkhangelsk Forestry in the bilberry spruce forests of different age classes (from IV to VIII). 10 trial plots were laid in clear stands or with a small mixture of birch and pine. To study the moisture content of spruce trunks, 15 sample trees (150 in total) were selected for each trial plot. The wood moisture content was determined on cores sequentially divided into 5-millimeter segments. Wood samples were weighed on a VT-500 torsion balance and dried in a drying cabinet at a temperature of 105 °C to a completely dry state. The relative moisture of wood was calculated. As a result of the conducted studies, the moisture of sapwood (from 44,8 to 45,9 %) and heartwood (from 32,2 to 36,1 %) was established. Two models of changes in the amount of water at different distances from the cambium were identified. The majority of trees (78–98 %) are characterized by a well-defined water supply zone, the moisture content of which is maximum at a distance of up to 25 mm from the cambium, after which it decreases sharply. The water supply zone is represented by approximately 40...50 outer annual rings. The second model is characterized by a gradual decrease in wood moisture along the radius from the periphery to the center of the trunk. Such a model of changes in the moisture content of wood in the cross-section of the trunk is rare, mainly in young trees. As the trunk diameter increases, the moisture content of sapwood decreases. There was no significant difference in the sapwood moisture of spruce trunks of different age classes. The sapwood moisture decreases from the root neck to 1.5 m in height of the trunk, varying from 52...53 % to 49,0...49,5 %.

Improving the accuracy of wood moisture content estimation in four European softwoods from Spain

Aim of study: To obtain improved models to predict, with an error of less than ± 2.0%, the gravimetric moisture content in four different softwoods commonly present in the Spanish and European markets, based on electrical resistance measurements. This improved moisture content estimation is useful not only for assessing the quality of wood products, especially in the case of laminated products, during the transformation and delivery process, but also for accurately monitoring the evolution of moisture in wood present in bridges and buildings, which is of great importance for its maintenance and service life improvement.Area of study: The study was carried out on samples of Scots, laricio, radiata and maritime pines of Spanish provenances.Material and methods: On 50x50x20 mm3 solid wood samples (36 per species, 9 per condition), conditioned at 20ºC (±05ºC) and 40±5%, 65±5%, 80±5% or 90±5% Relative Humidity (RH), electrical resistance and oven-dry moisture content was measured. The Samuelsson's model was fitted to data to explain the relationship between the two variables. The accuracy of the model was evaluated by the use of an external sample.Main results: With the proposed mathematical functions the wood moisture content can be estimated with an error of ±0.9% in the four species, confirming the effectiveness of this nondestructive methodology for accurate estimation and monitoring of moisture content.Research highlights: our results allow the improvement of the moisture content estimation technique by resistance-type methodologies.Keywords: Resistance-type moisture meter; species correction.Abbreviations used: MC: Moisture content; RH: relative Humidity; R: electrical resistance; RP: wood electrical resistance measured parallel to the grain; RT: electrical resistance measured perpendicular (transversally) to the grain; GM-MC: gravimetrically measured moisture content.

Improving the accuracy of wood moisture content estimation in four European softwoods from Spain

Aim of study: To obtain improved models to predict, with an error of less than ± 2.0%, the gravimetric moisture content in four different softwoods commonly present in the Spanish and European markets, based on electrical resistance measurements. This improved moisture content estimation is useful not only for assessing the quality of wood products, especially in the case of laminated products, during the transformation and delivery process, but also for accurately monitoring the evolution of moisture in wood present in bridges and buildings, which is of great importance for its maintenance and service life improvement.Area of study: The study was carried out on samples of Scots, laricio, radiata and maritime pines of Spanish provenances.Material and methods: On 50x50x20 mm3 solid wood samples (36 per species, 9 per condition), conditioned at 20ºC (±05ºC) and 40±5%, 65±5%, 80±5% or 90±5% Relative Humidity (RH), electrical resistance and oven-dry moisture content was measured. The Samuelsson's model was fitted to data to explain the relationship between the two variables. The accuracy of the model was evaluated by the use of an external sample.Main results: With the proposed mathematical functions the wood moisture content can be estimated with an error of ±0.9% in the four species, confirming the effectiveness of this nondestructive methodology for accurate estimation and monitoring of moisture content.Research highlights: our results allow the improvement of the moisture content estimation technique by resistance-type methodologies.Keywords: Resistance-type moisture meter; species correction.Abbreviations used: MC: Moisture content; RH: relative Humidity; R: electrical resistance; RP: wood electrical resistance measured parallel to the grain; RT: electrical resistance measured perpendicular (transversally) to the grain; GM-MC: gravimetrically measured moisture content.