Wood Moisture Content Research Articles

The radial gradient of moisture content of silver birch wood in different seasons

Silver birch ( Roth) is classified in diffuse-porous wood category. In this case structure of wood tissue is quite similar across whole cross-sectional area. The aim of this study was to analyse cross-section variability of moisture content (MC) of growing silver birch wood, significant hardwood species in Polish forests. Investigations were performed on 120 model trees. In the trunk of each model tree, an increment core was collected at breast height. Samples were collected of 30 different trees in four different seasons. The greatest MC was observed during winter, lowest MC in summer. Differences in MC were statistically significant only between winter versus spring, summer, and autumn. Distribution of MC on cross-section was similar in each season. The greatest average value was observed close to pith, then it was decreasing in bark direction. The greatest difference between observed in spring – 19.51% (p < 0.05) and lowest in autumn – 4.66%. Distribution of green density (GD) on cross section was inverse proportional to MC value. Variations in GD and MC are relevant for log transport planning, weight-scaling systems, lumber drying and dynamic assessment of stiffness. Therefore, from an environmental loss perspective, it is important to determine changes in MC and GD across the year.Betula pendula

The Effects of Polystyrene Species and Fiber Direction on Thermal Conductivity of Plywood

Thermal conductivity of wood material is superior to other building materials because of its porous structure. Thermal conductivity is used to estimate the ability of insulation of material. Thermal conductivity of wood material has varied according to wood species, direction of wood fiber, specific gravity, moisture content, resin type, and addictive members used in manufacture of wood composite panels. The aim of study was to determine the effect of polystyrene species and fiber direction on thermal conductivity of plywood panels. In the study, two different wood types (black pine and spruce), two different fiber directions (parallel and perpendicular to the plywood fiber direction), two different types of insulator (expanded polystyrene-EPS and extruded polystyrene-XPS) and phenol formaldehyde glue were used as the adhesive type. Thermal conductivity of panels was determined according to ASTM C 518 & ISO 8301. As a result of the study, the lowest thermal conductivity values were obtained in the perpendicular fiber direction of the spruce plywood using XPS as insulation material. The use of XPS as an insulation material in plywood has given lower thermal conductivity values than EPS.

Health Monitoring of Stress-Laminated Timber Bridges Assisted by a Hygro-Thermal Model for Wood Material

Timber bridges are economical, easy to construct, use renewable material and can have a long service life, especially in Nordic climates. Nevertheless, durability of timber bridges has been a concern of designers and structural engineers because most of their load-carrying members are exposed to the external climate. In combination with certain temperatures, the moisture content (MC) accumulated in wood for long periods may cause conditions suitable for timber biodegradation. In addition, moisture induced cracks and deformations are often found in timber decks. This study shows how the long term monitoring of stress-laminated timber decks can be assisted by a recent multi-phase finite element model predicting the distribution of MC, relative humidity (RH) and temperature (T) in wood. The hygro-thermal monitoring data are collected from an earlier study of the Sørliveien Bridge in Norway and from a research on the new Tapiola Bridge in Finland. In both cases, the monitoring uses integrated humidity-temperature sensors which provide the RH and T in given locations of the deck. The numerical results show a good agreement with the measurements and allow analysing the MCs at the bottom of the decks that could be responsible of cracks and cupping deformations.

Impact of Storage Method on the Chemical and Physical Properties of Poplar Wood from Short-Rotation Coppice Stored for a Period of 9\xa0Months

In addition to the use as biofuel, the utilization of poplar wood as a raw material from short-rotation coppice (SRC) became increasingly important in recent years. Because poplar SRCs are harvested during dormant season, wood storage is of particular importance to guarantee wood processing industries a continuous wood supply. The study focuses on the change of physical and chemical properties of poplar wood by the application of different storage strategies over a 9-month period. Therefore, a total amount of 60 m3 test log piles were set up in 2018 for six different storage variants: compact piles, compact piles with water sprinkling and oxygen exclusion, each with logs in bark and debarked. The effects on wood moisture content, equilibrium moisture content and wood density (ρ0) and the changes in the chemical components lignin, cellulose, hemicellulose and extracts were determined and evaluated. As expected, the wood moisture content changed in a wide range over the storage period, depending on the variant. The levels of equilibrium moisture (changes from − 4% to − 13.1%) as well as wood density (changes from − 2.61% to − 9.01%) decreased for all variants between start and end of storage. Changes in chemical composition were observed for all storage variants, which indicates microbial activity supporting the assumption that the observed mass loss is driven by wood decay. Overall, changes were more homogeneous for logs in compact piles compared to the other storage methods. Considering the weather conditions during the investigated period, the results indicate that storage in compact piles with debarked logs is the best method for the conservation of poplar wood from SRC.

Comparison of the Decay Behavior of Two White-Rot Fungi in Relation to Wood Type and Exposure Conditions.

Fungal wood decay strategies are influenced by several factors, such as wood species, moisture content, and temperature. This study aims to evaluate wood degradation characteristics of spruce, beech, and oak after exposure to the white-rot fungi Pleurotus ostreatus and Trametes versicolor. Both fungi caused high mass losses in beech wood, while spruce and oak wood were more resistant to decay. The moisture content values of the decayed wood correlated with the mass losses for all three wood species and incubation periods. Combined microscopic and chemical studies indicated that the two fungi differed in their decay behavior. While T. versicolor produced a decay pattern (cell wall erosion) typical of white-rot fungi in all wood species, P. ostreatus caused cell wall erosion in spruce and beech and soft-rot type I (cavity formation) decay in oak wood. These observations suggest that P. ostreatus may have the capacity to produce a wider range of enzymes/radicals triggered by the chemical composition of wood cell walls and/or local compositional variability within the cell wall.

Physical properties of Tectona grandis (Lamiaceae) juvenile wood thermally modified in a closed system

This paper reports the first results of the effect of an industrial closed-system thermal modification process on the physical properties of fast-growth teak wood (Tectona grandis L.f.). The wood (juvenile) came from thinning a 15–18-year-old plantation located in Mato Grosso state, Midwest Brazil, broken down into plainsawn battens measuring 25 × 70 × 1 070 mm (radial × tangential × longitudinal). The battens were from material close to the pith which was combined heartwood (≈75%) and sapwood. We sampled untreated and thermally modified battens, which were transformed into specimens for testing. The thermal modification was carried out at 160 °C in an industrial scale reactor, according to the parameters of the TanWood process, which is classified as a closed hygrothermal system. Twelve specimens by treatment (25 × 60 × 50 mm3 — radial × tangential × longitudinal) were conditioned in a climatic chamber set up at 35 °C and the relative humidity (RH) was raised stepwise (31%, 49%, 69% and 81%). Apparent density and equilibrium moisture content of the specimens were measured at every step. The latter was used as an index of wood hygroscopicity. For the statistical analysis, only the results of apparent density and moisture content at 35 °C and 69% RH were compared. At the end of the conditioning, the specimens were saturated in water, followed by oven-drying and then the total swelling (from saturated to oven-dried) was calculated. Thermally modified wood became less dense, less hygroscopic and more dimensionally stable than untreated wood. The apparent density and the equilibrium moisture content of wood were reduced by 20% and 18% respectively. With the continuous increase of RH from 31% to 81%, the thermally modified wood proportionally adsorbed less water than the untreated wood. The radial, tangential and volumetric total swelling were reduced by 25%, 5% and 15% respectively.

Biological distribution and environmental monitoring for the conservation of Janggyeong panjeon Depositories and Daejanggyeongpan (Printing Woodblocks of the Tripitaka Koreana) of Haeinsa Temple in Korea

Biological damage due to material characteristics and climatic change poses serious threats to wooden cultural heritage objects in Korea. This study is a preliminary survey for the preparation of a conservation/management plan for Janggyeongpanjeon (depositories of the Tripitaka Koreana Woodblocks), which is a UNESCO World Cultural Heritage Site, and Daejanggyeongpan (Printing woodblcoks of the Tripitaka Koreana), which is part of UNESCO's Memory of the World Programme. Over a period of two years, we monitored the distribution of insect and microbial species and the environmental condition in and around the Janggyeongpanjeon, including wood moisture content, and conducted relevant comparison and analysis. As a result, we compiled a list of species of wood-damaging organisms for the long-term conservation and management of the Janggyeongpanjeon (depository halls) and Daejanggyeongpan (woodblocks) and identified high-risk periods of biological damage for these wooden cultural heritage objects. The results of comprehensive analysis of the biological distribution and environmental condition demonstrated that conservation of the original form of the Janggyeongpanjeon and Daejanggyeongpan is based on a complex interplay of the material characteristics of the wood used, architectural features of the Janggyeongpanjeon enabling ventilation, and Daejanggyeongpan manufacturing technique.

Spectral Detection of Wood Moisture Content at 1899.703 Nm

In order to realize real-time, rapid and continuous measurement of wood moisture content, this paper studies the real-time measurement of wood moisture content based on near-infrared spectroscopy. In the experiment, a distributed feedback (DFB) laser with a central wavelength of 1899.703 nm was used as the light source, and poplar moisture content was chosen as the measured parameter to build the software and hardware system of the near infrared moisture detector. Because wood is a strong scattering medium, the modified Langbo-Beer law is adopted. The experimental measurement and data fitting of the moisture content of poplar wood showed that the true value of the moisture content of wood and the output power value of the laser measurement of the moisture content of wood could be fitted as a linear relationship within a certain range, and the correlation coefficient was above 0.90. The change trend of the measured value of the moisture content of wood was consistent with the true value, and the absolute error of the two was less than 0.15%. The experimental results show that the wood moisture content can be measured by near infrared technology.

Mechanical behaviour of wood compressed in radial direction: Part II. Influence of temperature and moisture content

This study investigated the influence of pressing temperature and moisture content on the mechanical properties of wood compressed in radial direction. Jack pine (Pinus banksiana) and balsam poplar (Populus balsamifera) specimens were tested under a combination of pressing temperature (20 °C, 55 °C, 90 °C, and 125 °C) and wood moisture content (2%, 7%, 12%, and 17%). The yield stress (σy) and modulus of elasticity (MOE) of the specimens were determined from the stress- strain response. It was found that an increase in either pressing temperature or moisture content of wood generally caused a decrease in the mechanical properties for both species. The t-test results revealed that jack pine specimens are more sensitive to changes in pressing temperature and wood moisture content than balsam poplar. For jack pine specimens, at any of the pressing temperatures, the moisture content of 12% was found to be a crucial level to start a significant decrease in σy and MOE, while at any of the moisture content, a change in temperature from 55 °C to 90 °C exhibited a significant change in σy and MOE. The regression models developed can be used to predict σy and MOE as a function of temperature and moisture content.

Indoor fine particulate matter and stove-use characteristics in homes heated by wood stoves: results from control homes in the KidsAIR randomized trial

Background/Aim: Household heating using wood stoves is common practice in many rural areas of the United States (US) and can lead to high concentrations of indoor fine particulate matter (PM2.5); yet there is limited research on household and behavioral factors that contribute to PM2.5 levels in such homes. Our aims were to characterize PM2.5 concentrations, evaluate household and stove-use characteristics that impact PM2.5, and assess the feasibility of interventions to lower PM2.5 in rural US homes that used wood stoves for heating.Methods: KidsAIR was a three-arm post-only randomized trial in wood stove households from three study areas. We measured indoor concentrations of PM2.5 over a 6-day sampling period during the winter and assessed household and stove-use characteristics. As the two intervention arms (education and air-filtration) were designed to impact PM2.5 concentrations, we focused these analyses on homes in the control arm (no intervention, n=93).Results: In preliminary analyses, the mean indoor PM2.5 concentration across all control homes was 28 µg/m3 (standard deviation [sd]=68), with higher concentrations in Alaska sites (47 µg/m3, sd=95, n=10) than Navajo Nation (NN) or Montana sites (29 µg/m3, sd=76, n=23; 25 µg/m3, sd=59, n=60). Stoves were often over 5 years old (54%) and of poor quality. More participants in NN (35%) reported heavy burning during PM2.5 measurement than Alaska (10%) or Montana (12%), and more participants in Alaska (70%) and NN (83%) burned wood <3 months after collection than in Montana (25%). Mean wood moisture content was lower in NN (6%) than Alaska (14%) and Montana (13%).Conclusions: We observed poor stove quality, inconsistent burn practices, and moderately high PM2.5 concentrations inside rural US homes that heated with wood stoves. Our findings highlight the need for, and the complex nature of, culturally- and regionally-appropriate interventions to reduce indoor air pollution in rural wood-burning homes.

Influence of wood anatomy on fiber orientation measurement obtained by laser scanning on five European species

In order to obtain high production rates of sawn timber, the sawmilling industry can use laser scanning, allowing knot detection and machine strength grading. In particular, laser scanners measure grain angle using the so-called tracheid effect on wood surface where an elliptic scattering of the laser light can be observed. This paper aims to describe the light scattering obtained by a laser beam projection on wood surface and to assess the accuracy of such fiber orientation measurement on five European species. Firstly, fiber orientation measurement error was assessed by rotating samples. Secondly, the description of the scattering effect was done considering ellipse axis ratios and areas. This was studied according to several parameters such as wood surface machining, moisture content, and orthotropic planes of symmetry. Fiber orientation measurement was successfully performed on all the tested species. The measurement error was below 1.6°, except for oak longitudinal–radial (LR) plane showing an error up to 3.1°. For most of the species, the error was higher in LR plane because of the influence of medullary rays. Despite the observation of major variabilities in laser light scattering, it was possible to measure the grain angles with a good accuracy for all investigated species.

Herbicidal effects of wood vinegar on nitrophilous plant communities.

In Europe, and many parts of the world, the number and variety of animal species on farmland is in marked decline. There is a need to search for alternatives that are safe for the environmental and are effective in controlling weeds. Wood vinegar from biomass pyrolysis may be an alternative for herb control. In this study, Wood vinegar (WV) pH, moisture content, and composition were analyzed, with subsequent assessment of the effects of WV on nitrophilous plant communities under natural conditions. The following three treatments were used: WV dissolved in water to form 25 vol% and 50 vol% dilutions and undiluted WV (100 vol%). The results showed a greater than 70% decrease in biomass at 7 days after WV application in all treatments. At the end of the sampling period (day 42), the plots treated with WV had four‐times less biomass than the controls. No significant differences were observed among different treatments, thus indicating that a 25% dilution may suffice for use as an herbicide. However, this concentration also produced the highest variability in results. The area cleared by the affected species was colonized by perennial species. At the end of the sampling, 80% of the area of the treated plots was occupied by perennial species, whereas this percentage was 30% in control plots. Electron micrographs showed that the epidermis of the treated plants was severely affected within a few hours of the treatment, particularly of the stomatal cells. The most affected species were those with smooth leaves without protective structures and those with lighter stems and leaves. The good herbicidal performance of WV notwithstanding, regulations must be clarified for its use as an herbicide.

Moisture monitoring in glulam timber structures with embedded resistive sensors: study of influence parameters

Today, a strong expansion in the construction of timber bridges is being promoted by the use of glulam. However, durability issues related to wetting/drying cycles limit their development. Timber bridge supervisors have therefore expressed their needs concerning continuous moisture content (MC) monitoring in timber structures. Checks on the MC of timber bridges are commonly based on the resistive method. A recent study carried out in the laboratory has shown the great potential of surface-type electrodes for local MC measurement in the laminated timber of glulam. Nevertheless, many parameters influence MC measurements and no information exists concerning surface electrodes. The novelty of this paper is to make the MC measurements with surface-type electrodes more reliable and accurate. In this study, the influence of electrode size and boundary conditions was therefore investigated. The influence of embedded sensors on the bending strength and elastic modulus of glulam beams was also evaluated in order to validate the electrodes instrumentation. Then, the influence of temperature and MC on the electrical resistance was studied, allowing a calibration curve to be established. The results show that small electrodes reduce the measurement uncertainties and therefore permit a more reliable estimation of MC. The boundary conditions also influence the measurements and should be considered. The embedded electrodes have no significant influence on the bending strength and elastic modulus of glulam beams. Finally, based on the literature review, a model for estimating wood MC was established, considering temperature variation.

Performance comparison and economic analysis of three solar dryer designs for wood using a numerical simulation

Three designs of a direct solar dryer for wood were evaluated with computer simulations. Calculations were performed using a heat and mass transfer model to obtain and compare the wood moisture content (MC) variation, as well as other drying parameters within the three designs. The findings showed higher drying temperatures and shorter drying times for solar dryers with large transparent cover areas (i.e., greenhouse-type dryers). Comparisons between glass covered and Plexiglas (PMMA) covered systems were also performed and the results indicated reasonably similar drying curves. The effect of using plastic cover was more prominent for dryers with low transparent areas (i.e., semi-greenhouse-type dryers), that is, 5% increase in the drying time for the greenhouse-type design and 10% increase for the semi-greenhouse-type designs. The economic analysis of the three designs revealed that double-glazing reduced the drying time, though it increased the cost of the covers by more than 130%. Inserting a Plexiglas cover over the glass cover resulted in a 25% decrease in the drying time and only a 57% increase in cost. Additionally, the combined plastic-glass configuration for the semi-greenhouse-type design resulted in a drying time comparable to this of the single glazing greenhouse-type design, though at a lower cost.

Prediction of the mechanical properties of wood using guided wave propagation and machine learning

Accurate nondestructive prediction of the mechanical properties of wood is a critical quality control task for timber grading. Currently, the ultrasonic wave method is widely used for this purpose, which overestimates the static mechanical properties of wood. To resolve this challenge, this paper proposes a robust machine learning-based model for predicting the modulus of elasticity (MOE) and modulus of rupture (MOR) of wood with varying moisture content (MC) using the guided Lamb wave propagation method. It combines the Lamb wave velocity with the “group method of data handling” to predict the mechanical properties of wood. The effect of MC and density on the Lamb wave velocity and the mechanical properties of seventy green poplar wood specimens were analyzed and discussed. It was shown that the Lamb wave velocity is highly sensitive to the MC, density, and mechanical properties of wood. It enables the guided Lamb wave propagation to be used as a reliable method for nondestructive timber characterization. The MOE and MOR of wood specimens predicted by the developed machine learning model were compared with those from the three-point bending tests, and the obtained accuracy was revealed to be higher than that obtained in the literature using the conventional ultrasonic method. It was concluded that the proposed combined Lamb wave propagation and machine learning method offers a strong tool for nondestructive prediction of the mechanical properties of wood.

Suitability of Wooden Shingles for Ventilated Roofs: An Evaluation of Ventilation Efficiency

Wooden shingles are a traditional roofing material on many culturally important building artifacts. Currently, the roof space of many traditional buildings is used for residential purposes and, consequently, cold roof constructions with ventilation layers are applied. In this study, it is evaluated whether the moisture content of wooden shingles is adversely affected by such constructions, compared with unvented shingle roofs over cold attics and whether a temporary closing of the ventilation gaps at the eaves contributes to a lower wood moisture content. Various sensors were installed in and around a building with wooden shingles on a ventilated roof and temperature, air moisture, and air speed in the ventilation layer were measured throughout a year. The findings show that the air speed in the ventilation layer can be adjusted from 0.06 to 0.25 m/s depending on the layout of the eaves. A hygrothermal model was applied to evaluate the effects of different ventilation operation modes and cardinal orientations of the roof on the moisture content of the wooden shingles. The results show that roof ventilation results in a 1% lower shingle moisture content on average than an unventilated roof over a cold attic. Finally, it is shown that the wood moisture content repeatedly reaches dangerous levels above 25% throughout a year, which is worse on north-facing roofs and, hence, measures to increase the dry-out are relevant.

Uji Ketahanan Api Kayu Sengon (Paraserianthes falcataria (L.) Nielsen) yang Diawetkan dengan Bahan Pengawet Natrium Silikat (Na2SiO3)

The results of this study indicate that the average value of air dry moisture content of sengon wood is 14.081%, the air dry density is 0.326 g/m3 and oven dry density is 0.295 g/m3. The highest average retention value was at 3 days immersion with a concentration of 7% i.e. 16.161 kg/m3 and the lowest was at 1 day immersion with a concentration of 3% i.e. 5.161 kg/m3. The highest value of burn intensity at 2 days immersion with a 3% concentration i.e. 16.249% and the lowest at 1 day immersion with a concentration of 7% i.e. 6.025%. Preservation of sengon wood using natrium silicate at a concentration of 3%, 5% and 7% and immersion for 1 day, 2 days and 3 days is less effective in holding the fire rate, because the value is still below the ASTM E69 standard (2002) i.e. 7.5. The effective test of preservative (W) obtained the highest value of burn intensity at 1 day immersion with a concentration of 7% i.e. 7,490 and the lowest value at 2 days of immersion with a concentration of 3%, i.e. 3,231. The maximum temperature ranges from 206.0-291.2°C and the cooking time ranges from 206.1-607.8 seconds.

Research on Moisture Content Detection of Wood Components Through Wi-Fi Channel State Information and Deep Extreme Learning Machine

Forest resources are among the most important wealth on the earth. Therefore, rational utilization of woods and improving its service efficiency will introduce profound social significance and economic benefits. But general surveys find that incorrect treatment of moisture content in wood products causes increasingly severe quality problems. So an efficient and nondestructive detection of wood moisture content is of extremely necessary and great importance. Whereas the present research tools are either time-consuming, environmentally sensitive, or too expensive to afford. This work proposes a convenient measurement of wood component's moisture content through Channel State Information (CSI) of the Wi-Fi signal and its corresponding high precise hybrid feature extraction via Bimodal Deep Extreme Learning Machine (BDELM). We first set up a moisture content detection equipment with commodity Wi-Fi devices, then we acquire and process the CSI data which pass through the wood component. After that, the BDELM is adopted to calculate the integration of CSI' amplitude and phase data. Finally, the moisture content will be accurately distinguished by offline training and an online testing procedure. Our results show that the proposed method could achieve a classification accuracy of moisture content detection above 96% for six different wood components, which demonstrates its effectiveness in application scenarios like wooden structure health monitoring.

Ultrasensitive moisture content characterization of wood samples by a cylindrical cavity resonator

Ultrasensitive moisture content sensing in wood samples is demonstrated employing a modified cylindrical cavity resonator geometry. A vertical sensing channel is introduced at the middle section of the cavity for sample placement. Field homogeneity inside the sensing channel is improved by a thin hollow quartz inset. A relation between the moisture content of wood and the resonance frequency for the dominant TM010-mode is extracted for the operation frequency range. Full-wave simulations are used to characterize and optimize the sensing technique. For experimental verification, a wood sample with 24% moisture content is allowed to dry in the cavity at room temperature for 24 h and its resonance frequency is monitored. The experiment is repeated for a sample which partially fills the sensing channel. Finally, the variation of the moisture content of a freshly cut tree branch is monitored in vitro. The experiments and simulations reveal that the proposed technique offers a very high sensitivity for characterization of the moisture content of wood samples of different radii, owing to the very high quality factor of the cylindrical cavity resonator. The technique is thus a promising candidate for the non-destructive monitoring of the moisture content of trees towards the prevention of forest fires and for the evaluation of products made from wood in industry.

Characterization of pecan shells and their effect on the physical properties and acceptability of smoked chicken breast.

Pecan shells were used as a source of smoke for cooked chicken breast and compared with samples smoked with hickory, mesquite, and apple tree wood. The wood moisture content ranged from 7.94% to 11.43%, whereas ash ranged from 0.97% to 3.11%. The particle size varied among the smoke sources, with chopped pecan shells having more pieces in the "coarse" category. Several properties related to quality of the cooked meat were measured including moisture content, water activity, color, cook loss, expressible moisture, and maximum shear force. Moisture content ranged from 70.13% to 71.72%, whereas pH ranged from 6.39 to 6.43. Chicken breasts smoked with pecan shells were darker (L* = 72.86 compared to 74.94 to 76.57) and slightly redder (a* = 5.71; b* = 25.70) than other samples. Color development was localized to the surface of the meat. Cooking loss did not differ significantly among the samples (26.13% to 27.03%) nor did expressible moisture (9.68% to 11.87%). Meat tenderness was assessed by shear values, but did not differ among the samples. Consumer panels showed that all samples were well liked. Samples smoked with mesquite had slightly lower scores for flavor and overall likability, whereas the scores for samples smoked with hickory, apple, or pecan shells were no different. PRACTICAL APPLICATION: Many meat products are cooked in the presence of smoke produced from burning hardwoods. This work shows that smoke can be produced from waste pecan shells, resulting in chicken breast with similar yield, texture, moisture retention, and acceptability as that smoked with hickory, mesquite, or apple tree wood.