The visual inspection of fresh cut spruce wood (
, L. Karst.) showed the variability of its colour. Wood visual inspection is a part of wood quality assessment, for example, prior to or after its ...processing. The detail spruce wood colour analysis was performed using spectrophotometric data. The colour was measured by the bench-top spectrophotometer CM-5 Konica Minolta. The spectrophotometer was calibrated with a built-in white standard and on air. The whole analysis was performed in an xy chromaticity diagram supplemented with coordinate
and CIE L*a*b* colour spaces. The ratio of the white chromophore amount to the amount of all achromatic chromophores is related to the
coordinate. The ratio of the chromatic chromophore amount to all chromophores amount is saturation. The constructed model of the spruce wood colour is composed of four chromophores. The white chromophore belongs to holocellulose. The black chromophore belongs to lignin. The saturation is influenced by two chromophores. One of them belongs to extractives, another to lignin. The amounts of chromophores correlated with the spruce wood chemical composition. The chemical composition was measured using the procedures of Seifert, Wise, Sluiter, and ASTM. Moreover, the wood colour is affected by the moisture content.
The anisotropic structure of wood will lead to a macroscopic anisotropic property in both mechanical strength and heat transfer. Previous experimental studies of wood materials were mainly focused on ...the mechanical property while their anisotropic thermal property in different environments is not sufficient. In this research, the anisotropic thermal performance of spruce wood is studied at different temperature, humidity, and mechanical load. The one-dimensional steady-state method and the transient plane source method are adopted to conduct the test. The thermal conductivity in both radial and longitudinal directions of spruce wood at temperature ranging from 25 °C to 422 °C, relative humidity ranging from 30 to 90 % RH, and mechanical load ranging from 0 to 20 MPa are obtained. The accuracy of the TPS method is validated using the 1D steady-state method. Both methods can be utilized to gauge the anisotropic thermal conductivity of spruce wood. Due to the unidirectional distribution of fiber, spruce wood has a longitudinal thermal conductivity that is roughly three times greater than its radial thermal conductivity. Among environmental conditions of temperature, humidity, and mechanical load, the thermal conductivity of spruce wood is varied with temperature more significantly, which is followed by humidity and mechanical load. The measurement uncertainty is also discussed.
Two cost-effective packing materials were used for n-butyl acetate removal in lab-scale biofilters, namely waste spruce root wood chips and biochar obtained as a byproduct from a wood gasifier. Three ...biofilters packed with spruce root wood chips: without biochar (SRWC), a similar one with 10% of biochar (SRWC-B) and that with 10% of biochar impregnated with a nitrogen fertilizer (SRWC-IB) showed similar yet differing maximum elimination capacities of 206 ± 27, 275 ± 21 and 294 ± 20 g m
−3
h
−1
, respectively, enabling high pollutant removal efficiency (>95% at moderate loads) and stable performance. The original biochar adsorption capacity was high (208 ± 6 mg
toluene
g
−1
), but near 70% of it was lost after a 300-day biofilter operation. By contrast, the exposed impregnated biochar drastically increased its adsorption capacity in 300 days (149 ± 7 vs. 17 ± 5 mg
toluene
g
−1
). Colony forming unit (CFU) and microscopic analyses revealed significant packing material colonization by microorganisms and grazing fauna in all three biofilters with an acceptable pressure drop, up to 1020 Pa m
−1
, at the end of biofilter operation. Despite a higher price (14 vs. 123 €m
−3
), the application of the best performing SRWC-IB packing can reduce the total investment costs by 9% due to biofilter volume reduction.
•Different wood particle sizes were studied for hemicellulose extraction at 170°C.•Smaller particle sizes gives faster extraction and slightly better yield.•The reaction order was 1.5st for 0.5–2mm ...and pseudo-first for 2–12.5mm particles.•Hemicellulose molar-mass dropped rapidly during the first 10min of extraction.•For maximum yield of high-molar-mass hemicelluloses 20min extraction was optimal.
The effect of five different wood particle size fractions between 0.5 and 12.5mm on hot-water extraction of acetylated water-soluble hemicelluloses from spruce wood with a batch extraction setup at 170°C was investigated. Extraction kinetics, with regard to particle size, was also studied. The purpose was to intensify the hemicellulose extraction for high molar mass hemicelluloses at high yield and purity. About 30% of the wood was dissolved and basically all the hemicelluloses could be extracted. The average molar masses of the extracted hemicelluloses decreased rapidly during the first 10min of the extraction, but were not much affected by the difference in wood particle sizes. Smaller particles resulted in higher extraction rates. The reaction order was established to be of pseudo-first order for particles above 2mm and 1.5st order for particles smaller than 2mm. The effective diffusion coefficient was determined to be 9.11×10−10m2/s.
•Macroscopically homogeneous stiffness matrix of spruce wood was formulated.•Nanoindentation at cell wall level was combined with macroscopic tensile tests.•Distribution of microfibril angle was ...determined via Bayesian inference.•Various types of experimental uncertainty and measurement errors were identified.
A simple approach to the identification of geometrical and material uncertainties of wood is presented. This stochastic mechanics problem combines classical micromechanics, computational homogenization and experimental measurements with Bayesian inference to estimate the model parameters including the characteristics of errors in macroscopic elastic properties of wood caused by randomness of microstructural details on the one hand and the experimental errors on the other hand. The former source of uncertainty includes, for example, variability in microfibril angle and growth ring density. Even such limiting consideration of random input illustrates the need for combined computational and experimental approach in a reliable prediction of the desired material properties. Tying the two approaches in the framework of Bayesian statistical method proves useful when addressing their limitations and as such giving better notion on the credibility of the prediction. This is demonstrated here on one particular example of spruce wood.
The material wood is sustainable, resource- and energy-efficient and recyclable. Its low density which ranges between 0.5 and 0.8g/cm3 makes from it an important material in the transport sector, in ...which weight reduction is a key factor against the background of energy savings and the associated reduction in CO2 emissions. Wood can be regarded as a low-damping material, due to its molecular structure and its relatively high modulus of elasticity. This characteristic is well known to musical instrument makers. For musical instruments with a resonance body (e.g. piano, harpsichord, viola, cello, double bass, cymbal, harp, zither and certain organ pipes) spruce is the first choice of wood. Since the parameters time, temperature and moisture content influence the mechanical properties of wood, it is considered to be viscoelastic. Especially, the moisture content of the wood can significantly alter its sound quality and, thus, its damping behaviour. In order to study that moisture influence, the individual drying behaviour of nearly 130 years old spruce and new spruce wood was investigated by damping measurements as a function of the temperature. The material damping of new spruce wood was found to be generally higher than that of old spruce wood. Furthermore, former results showed that the damping of new wood is less sensitive to moisture content changes, which corresponds to a stable tone colour. Activation energies for damping mechanisms were calculated based on data from the Arrhenius plot of both woods. These results suggest that further or stronger damping mechanisms are active in new spruce wood.
•The moisture content has a significant influence on the acoustic behaviour of wooden instruments.•The material damping of new spruce wood was found to be generally higher than that of old spruce wood.•The damping of new wood is less sensitive to moisture content changes (→ which corresponds to a stable tone colour).•The measured relaxation peak of new spruce wood at 383 K is supposed to be due to glass transition of lignin.•The damping peaks of the old spruce structure had an activation energy of approx. 100 kJ/mol.
•3D X-ray tomography reconstructions are performed at various relative humidity.•Evaluation of the 3D displacement fields due to relative humidity variations.•Development and validation of the ...hygro-mechanical model based on experiments.•Original approach for the identification of cell walls hygro-mechanical properties.
Being a hygroscopic material, wood is subjected to dimensional variation from a hygric state to another. These variations affect strongly its physical properties and consequently its structural functions in the building. The quantification of the swelling during the hygric transfer within the wood elements is still unknown by the researchers.
Hence, specimens with representative dimensions have been prepared and conditioned at two different relative humidity conditions. At each humidity state, the specimens have been scanned using X-ray micro-tomography to have access to their real morphology and evaluate their swelling. After that, a global approach has been set in order to model the hygro-mechanical behavior of the material and validate the model based on the experimental results.
To do so, the displacement fields of the volume from the dry to wet humidity states have been calculated with Digital Volume Correlation (DVC). Moreover, a microscopic hygro-mechanical model on the real 3D structure of the material has been proposed. The model has been further validated, through an identification approach, in order to minimize the gap between the numerical and the experimental displacements.
The results show good convergence of the model to the experiments, and an estimation of the Poisson coefficient and swelling coefficient of the cell walls.
This study presents a testing campaign aimed at evaluating the strength and stiffness properties of laminated veneer lumber (LVL) specimens. LVL is an engineered wood product composed of thin glued ...wood veneers whose use in construction for structural applications has increased due to its sustainability and enhanced mechanical performance. Despite LVL’s growing popularity, there is a lack of comprehensive information regarding stress–strain responses, failure modes, and the full set of strength and stiffness properties. These are particularly essential when LVL is employed in pure timber structures or composite systems such as steel–timber or timber–concrete load-bearing elements. This research aims to bridge this knowledge gap, focusing on crossbanded LVL panels, known as LVL-C, crafted from Scandinavian spruce wood, which is an LVL product with 20% of crossbanded veneers. The study explores LVL-C mechanical behavior in three primary orthogonal directions: longitudinal, tangential, and radial. A series of mechanical tests, including compression, tension, shear, and bending, was conducted to provide a thorough assessment of the material’s performance. In compression tests, different behaviors were observed in the three directions, with the longitudinal direction exhibiting the highest stiffness and strength. Tensile tests revealed unique stress–strain responses in each direction, with gradual tension failures. Shear tests showcased varying shear stress–strain patterns and failure modes, while bending tests exhibited significant strength and stiffness values in flatwise bending parallel to the grain and flatwise bending perpendicular to the grain. This paper summarizes the comprehensive testing results and discusses the obtained strength and stiffness properties of LVL-C panels, providing valuable insights into their mechanical behavior for engineering applications.
Thermal modification is a widely used wood protection method. This method has attracted attention because there are no toxic chemicals used in the process. The influence of thermal modification was ...investigated relative to the ignitability and the mass burning rate of Norway spruce wood (Picea abies). The spruce wood samples were subjected to temperatures of 100 °C, 150 °C, 200 °C, 220 °C, 240 °C, and 260 °C for durations of 1 h, 3 h, and 5 h. The treatment at temperatures higher than 200 °C resulted in a lower mass loss at 600 s and a lower average relative burning rate, but it did not influence ignition time, the flame-died-out time, and maximum relative burning rate. The class of reaction to fire of the spruce wood samples was not changed due to the treatment. Therefore, it can be stated that the thermal treatment at temperatures below 200 °C does not influence the fire safety of an important class of wooden products.
Development of new materials puts a great emphasis on saving production costs, energy, decreasing the amount and number of chemicals used during the manufacturing process. Bio-based materials can be ...ecologically produced and recycled after their lifespan, which saves the environment. The recent interest in bio-based materials led to the objective of this work. In this article, the structure of spruce wood (Picea abies) biodegraded by the white-rot fungus Trametes versicolor and brown-rot fungus Gloeophyllum trabeum was studied. Structure of the wood was observed macroscopically and microscopically. Classic and unusual stain combinations were used in this work. Ethanol was intentionally omitted in the process of making permanent mounts. It was done to preserve the coherence of the decayed microsections and to keep small fragments from being rinsed away. Results of the observations suggest that spruce wood decayed by these fungi could be used as an insulation material. Wood decaying fungi decrease the density of wood and increase its porosity. A low density and high porosity are important properties for insulation materials. According to the results, spruce wood decayed by Trametes versicolor would be more suitable to be used as an insulating material.
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