Wood Loss Research Articles

Losses in the manufacture of wooden building structures

Wood properties have successfully established themselves in the building structures. Very important to know expected wood losses in production. Losses are considered throughout the process of woodworking from sawmilling to obtaining glued blank. Research results were an assessment of losses in production of glued window beam as an example and substantiation of recommendations to production of wooden window blocks for choosing the type of primary source material: roundwood or edged sawn timber.

Effect of Heat Treatment on the Gas Permeability, Sound Absorption Coefficient, and Sound Transmission Loss of Paulownia tomentosa Wood

In this study, the gas permeability, sound absorption coefficient, and sound transmission loss of the Paulownia tomentosa wood were estimated using capillary flow porometry, transfer function method, and transfer matrix method, respectively. The longitudinal specific permeability constant of the Paulownia tomentosa wood with a thickness of 20 mm was 0.254 for the control sample and 0.279, 0.314, and 0.452 after being subjected to heat treatments at 100 °C, 160 °C, and 200 °C, respectively. The gas permeability was observed to be slightly increased by the heat treatment. The mean sound absorption coefficients of 20-mm thick Paulownia tomentosa log cross-section for the control sample and after being subjected to heat treatments at 100 °C, 160 °C, and 200 °C were 0.101, 0.109, 0.096 and 0.106, respectively. Further, the noise reduction coefficients of 20-mm thick Paulownia tomentosa log cross-section of the control sample and after being subjected to heat treatment at temperatures of 100 °C, 160 °C, and 200 °C were 0.060, 0.067, 0.062 and 0.071, respectively. The mean of sound transmission loss of the 20-mm thick Paulownia tomentosa log cross-section was approximately 36.93 dB. Furthermore, the gas permeability and sound absorption coefficient of the heat-treated Paulownia tomentosa discs slightly increased depending on the heat treatment temperature; however, the rate of increase was insignificant.

Ex-situ performance of extracts from naturally durable heartwood species and their potential as wood preservatives

To avoid the use of toxic synthetic chemicals due to their potential environmental impacts, the feasibility of using heartwood extracts of Tectona grandis and Cedrus deodara as wood preservatives against the subterranean termite, Reticulitermes flavipes and two basidiomycete decay fungi, Trametes versicolor and Rhodonia placenta, was investigated in laboratory experiments. There were no significant differences in feeding for R. flavipes fed solvent-extracted and non-extracted T. grandis in choice and no-choice tests with 100% mortality. Reticulitermes flavipes ignored non-extracted C. deodara (mass loss 1.93%) in choice tests and consumed significantly more solvent extracted C. deodara (mass loss 33.4%) with 64.9% mortality. Complete termite mortality (100%) was observed after exposure to non-extracted C. deodara versus 53% mortality when fed on extracted C. deodara in a no-choice test. When extracted and non-extracted blocks of each wood species were exposed to decay fungi, durability of both heartwood species was reduced post extraction. Extracts removed from wood shavings via Soxhlet extraction were used to treat non-durable southern pine and cottonwood. Both extracts imparted termite resistance to the non-durable species. Weight losses of both non-durable species were reduced at the highest extract concentration tested (10 mg ml−1), and were inversely related to extract concentrations and retentions. Significantly higher termite mortality was observed at the maximum extract concentration tested for either extract. Water leaching of non-durable wood species treated with T. grandis extract did not reduce termite resistance, and no significant difference between mortality of termites on leached versus non-leached samples was observed. Conversely, the weight loss of wood treated with C. deodara extract was significantly greater post leaching. T. grandis and C. deodara extracts showed no protective effects at tested concentrations against decay fungi when applied to non-durable southern pine or cottonwood.

Decaying woodrat (Neotoma spp.) middens increase soil resources and accelerate decomposition of contemporary litter

Ecosystem engineers can have broad-reaching impacts when they alter biogeochemical pools and processes, thus affecting resource availability. In the Chihuahuan Desert, woodrats (Neotoma spp.) build stick nests on the soil surface within Yucca baccata patches. We assessed the impacts of these middens on the underlying soil pools. We also assessed midden impacts on litter decomposition because decomposition exerts control over soil biogeochemical pools. We specifically focused on midden activity state, selecting Yucca patches with no midden, an active midden, or a decayed midden. Soil were analyzed for organic carbon, total nitrogen, and available nitrogen. To probe a mechanistic driver of soil biogeochemical pools, we measured litter mass loss of mesquite leaflets (Proposis glandulosa) and poplar wood (Populus spp.). Soil organic carbon, total nitrogen, available nitrogen and litter decay were all enhanced in decayed midden patches. These results support observations from other species in which the environmental modifications caused by ecosystem engineers persist beyond the life of the engineer. However, in this case the impacts of ecosystem engineers on biogeochemical pools and processes were greater for engineered structures that were not being maintained than for actively maintained structures. Woodrats have long-term impacts on spatial distribution of soil resources through their persistent middens.

Wood Modification by Furfuryl Alcohol Resulted in a Delayed Decomposition Response in Rhodonia ( Postia ) placenta

The aim of this study was to investigate differential expression profiles of the brown rot fungus Rhodonia placenta (previously Postia placenta) harvested at several time points when grown on radiata pine (Pinus radiata) and radiata pine with three different levels of modification by furfuryl alcohol, an environmentally benign commercial wood protection system. The entire gene expression pattern of a decay fungus was followed in untreated and modified wood from initial to advanced stages of decay. The results support the current model of a two-step decay mechanism, with the expression of genes related to initial oxidative depolymerization, followed by an accumulation of transcripts of genes related to the hydrolysis of cell wall polysaccharides. When the wood decay process is finished, the fungus goes into starvation mode after five weeks when grown on unmodified radiata pine wood. The pattern of repression of oxidative processes and oxalic acid synthesis found in radiata pine at later stages of decay is not mirrored for the high-furfurylation treatment. The high treatment level provided a more unpredictable expression pattern throughout the incubation period. Furfurylation does not seem to directly influence the expression of core plant cell wall-hydrolyzing enzymes, as a delayed and prolonged, but similar, pattern was observed in the radiata pine and the modified experiments. This indicates that the fungus starts a common decay process in the modified wood but proceeds at a slower pace as access to the plant cell wall polysaccharides is restricted. This is further supported by the downregulation of hydrolytic enzymes for the high treatment level at the last harvest point (mass loss, 14%). Moreover, the mass loss does not increase during the last weeks. Collectively, this indicates a potential threshold for lower mass loss for the high-furfurylation treatment.IMPORTANCE Fungi are important decomposers of woody biomass in natural habitats. Investigation of the mechanisms employed by decay fungi in their attempt to degrade wood is important for both the basic scientific understanding of ecology and carbon cycling in nature and for applied uses of woody materials. For wooden building materials, long service life and carbon storage are essential, but decay fungi are responsible for massive losses of wood in service. Thus, the optimization of durable wood products for the future is of major importance. In this study, we have investigated the fungal genetic response to furfurylated wood, a commercial environmentally benign wood modification approach that improves the service life of wood in outdoor applications. Our results show that there is a delayed wood decay by the fungus as a response to furfurylated wood, and new knowledge about the mechanisms behind the delay is provided.

Дослідження процесу пропарювання букових заготовок і пиломатеріалів

Зменшити втрати деревини від грибкових пошкоджень під час зберігання і транспортування можна завдяки проведенню теплової стерилізації. Теплову обробку деревини використовують у багатьох деревообробних процесах: виробництво лущеного і струганого шпону, у лісопильному виробництві, процесах гнуття та пресування. Одним із видів теплової обробки деревини є пропарювання. Відсутність процесу пропарювання букових пиломатеріалів після лісопилення є причиною значних втрат деревини від розтріскування, враження грибами та комахами. У виробничих умовах, під час пропарювання, не враховують багато чинників: особливостей будови деревини бука, її густини, теплових та механічних властивостей. Все це призводить до зайвих втрат матеріалу, теплової енергії та якісних показників букових пиломатеріалів. Тому дуже важливо досліджувати режими та технології пропарювання букових пиломатеріалів із збереженням їх фізико-механічних властивостей. Дослідження проведено з використанням пропарювального ковпака виробничого зразка. Здійснено експериментальні дослідження пропарювання букових заготовок та пиломатеріалів, яке охоплює початковий прогрів, сам процес пропарювання та охолодження. Внаслідок проведення експериментальних досліджень вибрано оптимальні режими пропарювання, які зберігають якісні фізико-механічні показники, такі як: запобігання втратам деревини під час зберігання і транспортування, вирівнювання забарвлення або надання деревині потрібного кольору, покращення міцності та пластичності, прискорення подальшого сушіння.

Imaging of Internal Defects of Polymer-Modified Wood Using Total Focusing Method

Polymer modification can improve the stability and corrosion resistance of wood, but it could create defects inside wood during the modification processing. Detection of defects inside polymer-modified wood can reduce wood losses and prevent the occurring of defects. Data simulation and tomographic imaging of polymer-modified wood internal defects were carried out using electromagnetic waves with nondestructive testing. This study constructed the polymer-modified wood models, simulated the electromagnetic scattering wave, and used the total focusing method to perform tomography of the defects in the polymer-modified wood. By analyzing the imaging characteristics of different types of defects, the effectiveness of electromagnetic waves in the detection of internal defects of polymer-modified wood was proved. This method can be extended to test internal defects of other high molecular polymers.

Modeling and prediction of devolatilization and elemental composition of wood during mild pyrolysis in a pilot-scale reactor

Mild pyrolysis, operated at 200–300 °C in an inert atmosphere, is a promising technology to produce sustainable materials (i.e., heat treated woods for construction and building) and solid fuels (i.e., torrefied woods or biochars for combustion and gasification). To aid in process and reactor design, the aim of this work is to conduct thermal degradation kinetics of wood. A two-step kinetics model is developed to predict the elemental composition (C, H, and O) and devolatilization dynamics of wood materials during heat treatment in a pilot-scale reactor by kinetic analysis. A hardwood poplar (Populus nigra) and a softwood fir (Abies pectinata) sever as feedstock, and the experiments are carried out at 200–230 °C with a heating rate of 0.2 °C min−1 in a low-pressure environment (200 hPa). The predictions in the weight losses of the woods are in a good agreement with the experimental data. The evolutions of solids, volatiles, elements (C, H, and O), and the heating values of treated woods are further analyzed. The predictions suggest that the intermediate solid is the main product, and almost all the woods are converted when the treatment temperature is as high as 230 °C. The devolatilization process, which is responsible for the mass loss of wood, can be clearly identified, and the volatile liberation amounts from poplar and fir at 230 °C are 17.05 and 12.44 wt%, respectively. The predicted HHVs of treated woods from the empirical formula are between 19.62 and 20.55 MJ kg−1, and the enhancement factors at the end of treatment are between 1.01 and 1.07 which is close to torrefied wood after light torrefaction. During the treatment, the extents of decarbonization, dehydrogenation, and deoxygenation in fir are all smaller than those in poplar, resulting from the lower intensity of devolatilization in the former.

Effect of the degree of decay on the electrical resistance of wood degraded by brown-rot fungi

There have been limited efforts to investigate the association between wood decay and electrical resistance; consequently, we have examined the change in the electrical resistance of wood progressively decayed by brown-rot fungi to elucidate the effect of the degree of decay. The rate of mass loss of wood was used as an indicator of the degree of fungal decay. The changes in the moisture content and ion concentrations were measured at various decay stages. The results showed a significant difference in the electrical resistances of sound wood and fungal-treated wood after 24 weeks. The electrical resistance significantly decreased with the exposure time. The degree of decay increased as the mass loss increased, resulting in the severe breakdown of cell walls and the accumulation of fungal mycelia. Empirical models related to the rate of mass loss and the percent decrease in the electrical resistance were established. The moisture content and cation concentrations increased to various degrees in decayed wood. This increase in the cation concentration was considered to play a dominant role in the decrease in the electrical resistance. The study results provide valuable information for developing an electrical resistance based method coupled with ion content measurements for incipient wood decay detection.

Preservation of durian timber and coconut timber with soursop leaf extract

Durian timber and Coconut timber grow a lot in the area of Gunung Pati Semarang, Central Java. The threat of biodeteoration in Indonesia as tropical area is quite high. Therefore, it is necessary to take protection measures in the form of preservation for prevention. The preservatives used in this study are natural preservative of soursop leaf extract. The preservation method used was cold soaking method with variation of concentration of preservative as follows: 0%, 5%, 10%, 15%, 20% and 25%. This study aims to figure out how significant the weight loss of timber and how durian wood and coconut wood’s resistance to termites based on the weight loss of timber. Result of examination of termite attack on Coconut timber with preservation of soursop leaf extract 0%, 5%, 10%, 15%, 20% and 25% obtained by weight loss of wood 17.57%, 13.43%, 10.61%, 7.67%, 5.50% and 4.20%. Meanwhile, the result of examination of termite attack on Durian timber with the concentration of soursop leaf extract 0%, 5%, 10%, 15%, 20% and 25% showed these following timber weight losses: 18.24%, 14.61%, 13.04%, 11.33%, 8.98% and 7.84%. Based on the wood resistance table, Durian timber with soursop leaf concentration of 20% and 25% were classified in the medium classification. Coconut timber with 15% and 20% soursop leaf concentrations were classified in the medium classification, while at 25% concentrations in resistant classification.

Development of a Monitoring and Control System for Timber’s Drying Process

Abstract The timber’s drying process is very important in reducing the wood losses and in improving the quality of the final products made of wood. Taking into consideration that the quality of the timber is directly related to the moisture content of the wood, the main problem refers to the control of the temperature and relative moisture in the drying chamber. Therefore, in order to fulfill these requirements, the automatic control strategies are needed, including the reducing of the energy consumption. The present paper highlights the components of the timber’s drying system, the design and the implementation of the On-Off control strategy and the monitoring interface.

Nondestructive Characterization of Dry Heat-Treated Fir (Abies Alba Mill.) Timber in View of Possible Structural Use

The use of heat-treated timber for building with wood is of increasing interest. Heat treatment improves the durability and dimensional stability of wood; however, it needs to be optimized to keep wood’s mechanical properties in view of the possible structural use of timber. Therefore, dry vacuum heat treatment varying the maximum temperature between 170 °C and 230 °C was used on fir (Abies alba Mill.) structural timber, visually top graded according to EN 338, to analyze its final weight loss, hygroscopicity, CIELAB color, and dynamic elastomechanical properties. It turned out that weight loss and total color difference of wood positively correlates with the increasing intensity of the heat treatment. The maximum 40% reduction of the hygroscopicity of wood was already reached at 210 °C treatment temperature. The moduli of elasticity in longitudinal and radial direction of wood, determined by ultrasound velocity, increased initially up to the treatment temperature of 210 °C, and decreased at higher treatment temperature. Equally, the Euler-Bernoulli modulus of elasticity from free-free flexural vibration of boards in all five vibration modes increased with the rising treatment temperature up to 190 °C, and decreased under more intensive treatment conditions. The Euler-Bernoulli model was found to be valid only in the 1st vibration mode of heat-treated structural timber due to the unsteady decrease in the evaluated moduli of elasticity related to the increasing mode number.

Persistency of Chlorpyrifos and Termiban (Imidacloprid) in soil against subterranean termites

Subterranean termites are considered to be one of the most destructive termites in urban areas in Pakistan. Different types of insecticides have been used to control subterranean termites. The present studies were conducted to evaluate the comparative persistency and effectiveness of Termiban (imidacloprid 5 SC) and Chlorpyrifos (40 EC) against subterranean termites in the three type of soils (sand, silt and clay) at different time interval. Two different concentrations (100 and 200 ppm) of selected insecticides were prepared and applied to soil in petri plates and termite were released at different time interval to record mortality. Results showed that at each time interval and concentration, mortality of termite was non-significantly different for both insecticides. When persistency of insecticides was tested under closed condition, results showed that lowest weight loss (8.60%) of wood was observed in Termiban treated soil at 200 ppm which was significant different from rest of the treatments. Similarly, under open conditions, at each time interval, there was significant more mortality of termites in soil treated with Termiban compared to Chlorpyrifos.

Обґрунтування конструкційних параметрів круглої пилки з комбінованим зубчастим вінцем

Вплив конструкційних параметрів пилки з комбінуванням зубців FZ/2WZ на точність поздовжнього пиляння деревини пояснено особливостями формування пропилу, що поділяється на два етапи: спочатку прорізний зубець FZ зрізає середню частину стружки, утворюючи паз у дні пропилу, який утримує пилку від бокового зміщення; наступні два зачисних зубці WZ послідовно формують ліву і праву частини пропилу, розширюючи утворений паз до ширини пропилу. За допомогою 3D-моделювання пилки та методу скінченних елементів у середовищі Solid Works досліджено вплив на робочу жорсткість пилки величини виступу прорізних зубців над колом різання та їхньої товщини і встановлено залежність у вигляді рівняння регресії другого порядку. За результатами аналізу отриманого рівняння регресії оцінено вплив кожного чинника та з'ясовано, що підвищення робочої жорсткості пилки до оптимального значення (150 Н/мм) можливе завдяки збільшенню виступу прорізного зубця, оскільки це дає змогу зменшувати товщину пилки. Визначено оптимальну величину виступу прорізного зубця 1,5 мм, яка забезпечує необхідну робочу жорсткість пилки і дає змогу зменшити товщину пилки до 2,2 мм. На підставі результатів експериментальних досліджень встановлено, що пилка з обґрунтованими конструкційними параметрами зубчастого вінця FZ/2WZ забезпечує точність пиляння в межах ±0,5 мм, дає змогу уникнути додаткових втрат деревини (близько 34 %) та електроенергії (до 20 %).

Wood decomposition in aquatic and terrestrial ecosystems in the tropics: contrasting biotic and abiotic processes.

Wood decomposition, a critical process in carbon and nutrient cycles, is influenced by environmental conditions, decomposer communities and substrate composition. While these factors differ between land and stream habitats, across-habitat comparisons of wood decay processes are rare, limiting our ability to evaluate the context- dependency of the drivers of decay. Here we tracked wood decomposition of three tree species placed in stream and terrestrial habitats in a lowland tropical forest in Panama. At 3 and 11 months we measured mass loss, wood nitrogen and wood polymer concentrations, and sampled wood-associated fungal and bacterial communities. After 11 months of decay we found that mass loss occurred 9% faster in streams than on land, but loss of cellulose, hemicellulose and lignin did not differ between habitats. We also observed large differences in microbial decomposer communities between habitats. Overall, we found faster mass loss of wood in water, but no differences in biotic decay processes between habitats despite distinct microbial communities in streams and on land. Our research challenges the assumption that wood decays relatively slowly in water reflecting unfavorable environmental conditions and a limited capacity of aquatic microbial communities to effectively degrade wood polymers.

Application of time–temperature–humidity superposition to the mass loss of wood through hygrothermally accelerated ageing at 95–140 °C and different relative humidity levels

Spruce wood specimens were hygrothermally treated at different temperatures (T, 95–140 °C) and relative humidity during heating (RHh, 0–92%) to measure the loss in dry mass (ML) due to the treatment. The ML was approximated by a power function of the heating duration t, and the plots of ML versus t were successfully superposed as a single master curve by shifting the plots along the t axis using the shift factors aT and aH, representing the effects of T and RHh, respectively. The apparent activation energies calculated from the linear correlation between ln(aT) and the reciprocal of absolute temperature were 109–116 kJ/mol, almost independent of RHh. Plots of aH versus RHh showed sigmoid shapes, suggesting that the aH value depended on the moisture content of the wood. The shift factors allowed the prediction of the ML of wood by hygrothermal treatment at arbitrary T and RHh. The predicted ML values showed good agreement with experimental ML values available in the literature.

Evaluation of Deterioration of Larix kaempferi Wood Heat-treated by Superheated Steam through Field Decay Test for 12 Months

In this study, the decay resistance of larch wood, which was heat treated by superheated steam, was evaluated by the field decay test. During the field decay test of 12 months, non-treated wood has been severely damaged by termite, however, no visible damage has occurred in the preservative-treated wood and superheated steam heat-treated wood. Results of field decay test showed approximately 5% mass loss of the non-treated wood and the preservative-treated wood, and approximately 1% mass loss of the superheated steam heat-treated wood. After the field decay test for 12 months, the residual amount of preservatives remaining in the preservative-treated wood was lower than that before the field decay test. It was considered that the preservative was partially eluted during the field decay test, and the mass loss of the preservative-treated wood was thought to be similar to that of the non-treated wood. Through this study and additional long-term monitoring test, superheated steam heat treatment can be considered to be an environmental-friendly method to enhance the decay resistance of wood against rot fungi and/or insect without chemical treatment such as preservative injection.

The loss of large wood affects rocky mountain trout populations

AbstractWestern U.S. rivers are currently influenced by legacy effects of reduced large wood (LW) loading and retention that has substantially reduced in‐stream habitat complexity. Large wood is typically associated with streams in undisturbed old‐growth forest and in the correct geomorphic context can drastically alter stream and valley habitat complexity. Streams withLWare typically multichannel and depositional, while streams lackingLW, due to relatively recent wildfire or logging (<200 years ago), are usually single channelled and erosional. We compared population biomass and individual growth rates of Brook TroutSalvelinus fontinalisin streams across a gradient of wood volumes. At both the square metre and valley length scales, standing stock biomass of aquatic invertebrates was the best predictor of trout biomass. However, at the valley scale, the number of pools was important in predicting trout biomass in combination with standing stock biomass of aquatic invertebrates. Individual growth rates of age‐1 Brook Trout were negatively affected by increasing density; however, growth rates for the largest and smallest individuals at each site were unaffected by density. Our results suggest the pool habitat created byLWacts synergistically with prey availability to dramatically increase trout populations. However, in streams lacking LW, negative effects of detrimental land use practices have persisted >100 years, suggesting that recovering lost animal production in mountain stream networks will only occur at decadal to century time scales.

Swelling restraint of thermally modified ash wood perpendicular to the grain

The paper reports on creep of ash wood (Fraxinus excelsior L.) thermally modified at 180 and 200 °C, and subsequently subjected to compression in tangential and radial directions and simultaneously wetted, from the moisture content (MC) of 6% to above the fibre saturation point (FSP). The compressing load made 0.00, 0.25, 0.50 and 0.75 of impact stress at the proportional limit (Rc). The compression stress needed to restrain the swelling of wood, the so-called swelling pressure, was indirectly determined from isochrones of mechano-sorptive creep. The most important finding was that thermal modification reduces the strain of ash wood subjected to compression perpendicular to the grain to a degree proportional to the mass loss. The compression stress needed to restrain the swelling of thermally modified wood is ca. 10 and 20% smaller in the tangential and radial directions, respectively. This effect leads to a reduction in the anisotropy of swelling pressure of thermally modified wood perpendicular to the grain. Moreover, although upon thermal modification the mass loss of wood takes place, at the MC of 6% it shows practically the same modulus of elasticity (MOE) and Rc as the unmodified wood. After wetting to MC higher than the FSP, the thermally modified wood at 200 °C shows significantly higher MOE and Rc than the wood modified at 180 °C and untreated wood. Reduction of wood hygroscopicity, an inevitable effect of thermal modification, also reduces the range of changes in mechanical properties of wood caused by the increase in its MC to the FSP.

Effects of White Mulberry (Morus alba) Heartwood Extract Against Reticulitermes flavipes (Blattodea: Rhinotermitidae).

Heartwood extract from white mulberry (Morus alba L.) (Rosales: Moraceae) were investigated for antitermitic activity against Reticulitermes flavipes (Kollar) (Blattodea: Rhinotermitidae) in laboratory experiments. An ethanol:toluene (2:1) solvent system was used to remove extract from heartwood shavings. A concentration-dependent feeding response and mortality were observed for termites exposed to a concentration series range of 1.25 to 10 mg/ml of extract based on their dry weight. Results showed that maximum termite mortality occurred at 10 mg/ml. Based on the concentration series data, LC50 was calculated at 1.71 mg/ml. In filter paper feeding and repellency assays, extract significantly decreased the total number of gut protozoa compared with untreated and solvent controls. After feeding on filter paper treated at 10 mg/ml for 2 wk, protozoan populations were reduced by >55%. In choice and no-choice tests with mulberry heartwood, greater wood loss from termite feeding was found on solvent extracted blocks compared with nonextracted. Complete (100%) mortality was observed after feeding on nonextracted blocks compared with extracted blocks. Heartwood extract from white mulberry imparted resistance to vacuum pressure treated, nondurable southern pine and cottonwood. At every concentration tested, 100% mortality was observed after feeding on extract-treated southern pine or cottonwood. GC-MS analysis of extract showed high levels of the phenol compound, resorcinol. Results indicated that heartwood extract from white mulberry have antitermitic properties and might be potentially valuable in the development of environmentally benign termiticides.