WOOD RESEARCH Volume 70, Number 4, 2025
ANDREJ PAŽITNÝ, JURAJ KRIŠTA, and MARTA PÁTEKOVÁ

IMPROVING SHEET MATERIAL PROPERTIES IN PAPERMAKING FROM SECONDARY FIBER AND CORN KERNEL’S CASING

The paper is focused on monitoring the impact of corn kernel’s casing content added to old corrugated containers on density, brightness, ultimate tensile load, tensile index, tensile energy absorption, breaking length, tensile strength, relative elongation, air resistance of paper sheet according to Gurley and zero-span tensile strength. A content of 40 % and 60 % corn kernel’s casing added to secondary fiber based on old corrugated containers was tested. Suspensionsprepared by acidification and beating were subjected to chelation and three-stage bleaching.The bleaching method consisting of three steps was applied in two series – acidified and beaten pulp suspension with Schopper-Riegler (°SR) beating degree at level of 72 °SR.The first bleaching step includedperoxide bleaching with added sodium hydroxide, chlorine dioxide bleaching and peroxide bleaching in an alkaline environment. The effect of chemical and hydro-mechanical treatment on the resulting physical and mechanical characteristics of prepared paper sheets was investigated.

WOOD RESEARCH Volume 70, Number 4, 2025
LUKÁŠ VELEBIL, ŠIMON MATĚJKA, Petr Kuklík, Jan Pošta, MARTIN HATAJ, and JAN JOCHMAN

ANCHORING OF CROSS-LAMINATED TIMBER SHEAR WALLS

This paper presents a validated finite element model of a cross-laminated timber (CLT) wall-to-floor connection and compares its predictions with results from a full-scale shear wall test. The CLT wall and floor panels are modelled as orthotropic shell elements, while the discrete connectors (tension anchors, angle brackets and the screw connection between floor panels) are represented by line hinges with nonlinear load-slip relationships.These relationships are derived from dedicated component tests on tension anchors, shear brackets and screw head embedment. The model is analysed in nonlinear static steps corresponding to the experimental loading sequence. Vertical slip along the wall-to-floor interfaces and the global lateral load-displacement response of the wall are extracted and compared with measurements. The results show that the simplified line-hinge representation reproduces both the global stiffness and the local deformation pattern in the joints with satisfactory accuracy for design-oriented analyses.

WOOD RESEARCH Volume 70, Number 4, 2025
FAUZAN FAHRUSSIAM, ANDI TRI LESTARI, and DINI LESTARI

PHYSICAL PROPERTIES AND NATURAL DURABILITY OF INDONESIAN COMMERCIAL WOODS MODIFIED BY SURFACE CHARRING AND COATING APPLICATION

This study evaluated the characteristics of Indonesian commercial wood species modified through the yakisugi surface finishing technique combined with coating application. Four wood species, teak (Tectona grandis), pine (Pinus merkusii), mindi (Melia azedarach), and mahogany (Swietenia mahagoni), were treated using a mini butane torch to produce charred surfaces either with or without the removal of carbon layers, followed by transparent exterior coating. The treatments were assessed for volumetric swelling, water absorption, and termite resistance through a 12-week graveyard test. Results showed that combining surface charring and coating improved dimensional stability and termite resistance compared to untreated wood. The durability class of teak and pine increased to class II, while mindi and mahogany showed no significant changes. The findings suggest that surface charring combined with coating provides a simple, practical, and effective finishing method to enhance the performance of tropical commercial woods.

WOOD RESEARCH Volume 70, Number 4, 2025
TOMÁŠ MELICHAR, SILVESTR VASAS, MICHAL KŘIŠTOF, ONDŘEJ KEPÁK, AMOS DUFKA, DANUTE VAIČIUKYNIENĖ, and JIŘÍ BYDŽOVSKÝ

THE ANALYSIS AND MECHANICAL ACTIVATION OF WASTE DUST FROM PROCESSING OF CEMENT-BONDED PARTICLEBOARDS

The article presents research focused on the properties and mechanical activation of waste dust (WDC) generated during the processing of cement-bonded particle boards (CBPs). Six samples of WDC were taken directly from the CBP manufacturer CIDEM Hranice, a.s.during 2024. The properties ofWDC samples were analysed with regards to its application in CBP as an active component of cement matrix. The particle size, distribution, specific surface area, density, wood content, loss on ignition, chemical and mineralogical composition, pH, microstructure, etc. were assessed. The WDC samples were then subjected to homogenization and mechanical activation in a planetary mill. The potential of mechanically activated WDC from CBP processing as a partial cement substitute was proved. While the activated WDC in an amount of 20% showed a 32% decrease in compressive strength, an 19% increase in flexural strength was also observed. As part of follow-up research, the activation process will be optimized by increasing the intensity and duration of grinding.

WOOD RESEARCH Volume 70, Number 4, 2025
DOAN VAN DUONG and MASUMI HASEGAWA

NONDESTRUCTIVE PREDICTION OF BENDING STRENGTH OF PINUS MASSONIANA LAMB. LOGS AND SMALL CLEAR SPECIMENS USING STRESS-WAVE MEASUREMENTS

The main objective of this study was to investigate the relationships between stress-wave velocity measured in logs and small clear specimens and the bending strength of Pinus massoniana trees planted in northern Vietnam. Stress-wave velocity (SWVL) and green wood density (WDL) were measured on logs collected from different heightlevels of 23-year-olds P. massonianatrees. Stress-wave velocity (SWVS), wood density (WDS), and bending strength (MOR) were subsequently determined on small clear specimens prepared from the logs. Regression analyses revealed significant correlations between SWVL and MOR (r = 0.73, P < 0.001) and between SWVS and MOR (r = 0.80, P < 0.001). These results show that stress-wave velocity measurements, whether taken on logs or small specimens, are effective for segregating P. massoniana lumber resources based on MOR. A more accurate prediction of strength was obtained when stress-wave velocity and log or specimen wood density were used together to calculate the dynamic modulus of elasticity of logs (DMOEL) or specimens (DMOES), respectively. The correlation coefficients were 0.82 (P < 0.001) between DMOEL and MOR, and 0.93 (P < 0.001) between DMOES and MOR.

WOOD RESEARCH Volume 70, Number 4, 2025
JINGGUI WANG, MING LI, SAIYIN FANG, TINGTING DENG, JIAXIN GUO, ERZHUANG ZHAI, and WENTAO XU

THE STUDY ON THE DAMAGE CHARACTERISTICS OF PINUS SYLVESTRIS VAR. MONGOLICA UNDER DIFFERENT MOISTURE CONTENTS

This study investigated the effects of moisture content (0%, 12%, 20%, 30%, 40%, 50%) on the mechanical behaviour and damage evolution of Pinus sylvestris var. mongolica three-point bending tests. A Weibull distribution model quantified damage progression, extracting scale (λ) and shape (k) parameters. Results revealed moisture regulated failure mechanisms, Low moisture (≤20%) induced brittle fracture (high k, low λ) with tensile crack dominance and stress concentration. High moisture (≥30%) promoted ductility (low k, high λ) via enhanced λ, driven by shear cracks. Mixed cracks persisted across all stages. Moisture altered cell wall plasticization, inter-fibre friction, and interfacial bonding, modulating damage evolution. Weibull modelling effectively captured stage dependent damage variable trends. Increased moisture facilitated fibre slippage and interlayer shear through lubrication and cell wall softening.This work establishes quantitative links between moisture content, mechanical response, and micromechanical damage mechanisms in wood, providing insights for moisture dependent structural applications of engineered timber.

WOOD RESEARCH Volume 70, Number 4, 2025
DWI SUKMA RINI, IKUMI NEZU, AGUS NGADIANTO, DENNY IRAWATI, JYUNICHI OHSHIMA, SHINSO YOKOTA, and FUTOSHI ISHIGURI

DECAY RESISTANCE OF THREE BAMBOO SPECIES NATURALLY GROWING IN LOMBOK ISLAND, INDONESIA

Culms of three bamboo species, Bambusa vulgaris, B. maculata, and Gigantochloa atter, collected from four natural stands in Lombok Island, Indonesia, were decayed by a white-rot fungus, Trametes versicolor, for 90 days. The obtained data were analysed by a mixed-effect model with a random effect of the sites to evaluate the geographic variations of decay resistance of the culms. Mean mass loss values were 16.3% for B. vulgaris, 20.2% for B. maculata, and 13.8% for G. atter. No significant difference in mass loss was found among the three species. Mass loss was positively correlated with amounts of hot-water extracts and organic solvent extracts in B. vulgaris, and with amounts of hot-water extracts and 1% NaOH extracts in B. maculata. As a result of mixed-effect modelling, the variance component ratio of the sites ranged from about 10 to 30%, suggesting that geographic variation was recognized in the culm decay resistance.

WOOD RESEARCH Volume 70, Number 4, 2025
SHUTING XU, DAWEI GU, XIWEN SUN, QIULI WU, HUIJUAN ZHANG, JIAN YANG, XIAOJUN YANG, and ZELI QUE

CONNECTION PERFORMANCE OF LENGTH-WISE FINGER-JOINTED EUCALYPTUS

The high density and large amount of extractives of eucalyptus (Eucalyptus maculata) wood are very unfavorable for the production of its finger-jointed timber. This study examined the mechanical properties of finger-joint nodes during the pressing and unloading processes at the ends, and investigated the effects of chemical agents and heat treatment methods on the performance of finger-joint connections. The results indicated that high end-pressure was crucial for maintaining the stability of finger joints, as a reduction in pressure led to significant displacement relaxation and springback. The high extractive content in eucalyptus had different effects on the bonding performance of different adhesives: polyvinyl acetate (PVAc) adhesive exhibited superior bonding performance, with tensile strength and flexural strength reaching 12.21 MPa and 52.61 MPa, respectively. Furthermore,heat treatment and anhydrous ethanol pretreatment can effectively reduce the impact of extractives at the joint interface, thereby enhancing the bonding strength. Compared to untreated controls, heat treatment improved tensile and flexural strength by 5.7% and 0.6%, respectively, while anhydrous ethanol pretreatment resulted in increases of 3.8% and 7.6%.

WOOD RESEARCH Volume 70, Number 4, 2025
RENÁTA KUTLÁKOVÁ, PETER RANTUCH, JOZEF MARTINKA, MARGARÉTA TIBENSKÁ, TOMÁŠ ŠTEFKO, and IGOR WACHTER

CHARACTERIZATION OF IGNITION PROCESS OF THERMALLY TREATED WOOD BY CONE CALORIMETER

This study examines the influence of thermal treatment on the ignition properties of Norway spruce (Piceaabies (L.) H. Karst.) and sessile oak (Quercus petraea (Matt.) Liebl.) wood. Using a cone calorimeter both untreated and thermally modified samples (180°C for 6 h) were analysed to determine key fire modelling parameters: combustion efficiency, critical heat flux, ignition temperature, thermal inertia, and thermal response parameter. Obtained results reveal that thermally treated wood exhibits higher combustion efficiency than its untreated equivalent, with spruce generally outperforming oak. The effect of thermal treatment on other properties was species-dependent. Thermally treated spruce showed an increase in critical heat flux and a decrease in both thermal inertia and the thermal response parameter. Conversely, thermally treated oak displayed a reduction in critical heat flux and an increase in both thermal inertia and the thermal response parameter. These results highlight the complex, species-specific effects of thermal modification on the fire behaviour of wood.

WOOD RESEARCH Volume 70, Number 4, 2025
DUŠAN JOKANOVIĆ, VESNA NIKOLIĆ JOKANOVIĆ, JOVANA PETROVIĆ, MARKO MARINKOVIĆ, BOJAN TUBIĆ, ANDREJA LAZOVIĆ, and FILIP JOVANOVIĆ

MORPHO-ANATOMICAL TRAITS OF QUERCUS CERRIS AND Q. RUBRA ONE-YEAR-OLD SEEDLINGS CULTIVATED IN DIFFERENT CONTAINER TYPES

The paper investigated the variability of the morphological-anatomical traits of one-year-old oak seedlings (Quercus cerris L. and Quercus rubra L.) produced in three different container types (Hiko, Plantagrah, biodegradable). A two-factorial ANOVA showed for the morphological characteristics (root collar diameter and height) statistically significant difference between the species and between the containers, too. The interaction between the variability factors (container type and species) also affects height and root collar diameter. As for the obtained results of two-factorial ANOVA for anatomical parameters (wood, bark, pith proportion, and vessel width), statistically significant differences were obtained for all of them between species, as well as between container types. On the other hand, the interaction of container type and species does not affect vessel width and bark content unlike wood and pith proportion. Comparing the species, it can be concluded that the average values of all traits, apart from vessel width, are higher in Q.rubra L. The largest dimensions of all elements regardless of the species were obtained for Hiko, then Plantagrah, and the smallest for biodegradable container.

WOOD RESEARCH Volume 70, Number 4, 2025
VLADIMÍR KUŇA and JOZEF BALBERČÁK

THE INFLUENCE OF PULP BEATING AND PAPERMAKING AGENTS ON THE CHARGE DENSITY OF FIBERS AND COLLOIDAL PARTICLES IN PAPERMAKING WATERS

The first part of the paper is focused on monitoring the impact of the beating process on the charge density of fibres and colloidal particles in water in the production of tissue papers. Three types of pulps most commonly used were tested: long-fibre pine pulp, short-fibre eucalyptus pulp and short-fibre hardwood birch pulp. In the range of beating degrees from 14°SR to 35°SR, the impact of beating on the charge density of fibres expressed as Zeta potential, the charge density of colloidal particles expressed as PCD value and the conductivity of the paper suspension were evaluated. The paper also evaluates the impact of beating on the physical and mechanical properties of laboratory sheets. The second part of the paper is focused on monitoring the impact of papermaking aids, in the production of tissue papers, on the charge density of fibres and colloidal particles in water. The most significant impact was demonstrated by the agent for increasing the wet strength of paper. In these laboratory tests, pulp mixtures were used that were prepared by separately beating individual pulps to a beating degree of 25°SR.

WOOD RESEARCH Volume 70, Number 4, 2025
QINYI GU, HONGHAI LIU, and TAO LI

THE STUDY OF SURFACE DENSIFICATION AND TEMPERATE SUPERHEATED STEAM MODIFICATION FOR RUBBERWOOD

This study aimed to develop a high-value wood composite by surface-densification combined with temperate superheated steam modification technology. Rubberwood boards were hot-pressed, the impact of the peak density and thickness of densified layer on the physical and mechanical properties of wood were studied. In this study the platen temperature was kept constant, after hot-pressing the platen cooling phase was omitted replaced by special compression pressure decreasing and steam discharging technic, which could save much energy and time. Superheated steam treatment (190°C for 1.5 h) and conditioning (110°C for 2 h) were recommended for improving dimensional stability and durability. Study results indicated that the surface hardness and modulus of rupture of surface-densified followed by superheated steam modified rubberwood increased by 55.9% and 41.6% compared with non-densified one respectively. Dimensional stability improved substantially. The durability was improved to ‘durable class’ according to GB/T 13942.1-2009.

WOOD RESEARCH Volume 70, Number 4, 2025
EMRE BIRINCI

INVESTIGATION OF THE EFFECT OF EXTREME TEMPERATURE ON SCREW DIRECT WITHDRAWAL RESISTANCE OF WOOD PLASTIC COMPOSITE DECKING PROFILES

In this study, the effects of extreme temperatures on screw direct withdrawal resistance (SDWR) of wood plastic composite (WPC) decking profiles were systematically investigated. Commercially produced WPC decking profiles were tested at different temperature levels (-40°C, -20°C, 0°C, room temperature, +40°C and +60°C); their effects on SDWR were evaluated by controlling parameters such as screw diameter (3.0 mm and 3.5 mm) and pilot hole diameter (60%, 70% and 85%). Additionally, the relationships between Shore D hardness and SDWR measured at each temperature level were revealed through statistical analyses. The results show that as the temperature increases, Shore D hardness decreases and accordingly, significant decreases occur in SDWR. The highest SDWR was obtained at -40°C temperature, 60% pilot hole ratio and 3.5 mm screw diameter combination. This highlights the influence of material hardness and screw-material interaction on joint performance. According to Pearson correlation analysis, a strong and statistically significant (r=0.939, p=0.0055) positive relationship was determined between Shore D hardness and SDWR.

WOOD RESEARCH Volume 70, Number 4, 2025
YANG ZHENG, MENGQING KE, CHENYANG CAI, XIAO ZHONGYANG, and HONGHAI LIU

COMPARATIVE STUDY ON THE HEAT TREATMENT OF DALBERGIA LATIFOLIA ROXB. WOOD UNDER ATMOSPHERIC PRESSURE AND VACUUM CONDITIONS

This study comparedatmospheric heat treatment (AHT) and vacuum heat treatment (VHT)of Dalbergia latifoliaRoxb. at 180°C for 6 hto improve dimensional stability. Through multiple tests, it analyzed their effects on the wood. Results showed VHT caused milder chemical changes, preserving hydroxyl and lignin structures while AHT severely degraded hemicelluloses. VHT led to lower weight loss 0.45% vs 1.25%, better dimensional stability with a greater reduction in radial swelling 0.84% vs 1.34%, higher mechanical strength (modulus of rupture: 118.22 MPa vs 95.83 MPa; modulus of elasticity 9361.50 MPa vs 8558.34 MPa), and a smaller color change ΔE*: 9.79 vs 18.65. Overall, VHT can balance performance improvement and minimize damage to the wood’s structure and aesthetics.

WOOD RESEARCH Volume 70, Number 4, 2025
MIKKEL NÜSSLER, JOHN BANG MATHIASEN, and JACOB KJÆR ESKILDSEN

DECAY RESISTANCE AND FIRE CLASSIFICATION OF SURFACE-CARBONIZED SCOTS PINE WITH POST-CARBONIZATION LINSEED OIL AND SODIUM SILICATE TREATMENT

To determine the effect on decay resistance and fire classification of applying linseed oil or a sodium silicate solution to surface carbonized Scots pine, two different experiments were conducted. An AWPA E10 standard (AWPA 20216) soil block test was conducted to determine the decay resistance of eight unique treatment configurations, and fire classification following the EN 13823:2010+A1:2014 / EN 14915:2013 was conducted to determine the fire classification of façade panels treated with pure linseed oil and a 40/60 mix of linseed oil and sodium silicate respectively. The study showed that decay resistance measured as average mass loss (AML%) improves significantly by surface carbonization but depends on the intensity of the treatment as well as the application of surface sealing substances applied post-carbonization. Carbonized Scots pine façade panels without any post-carbonization treatment as well as carbonized Scots pine treated with sodium silicate or a 40/60 mix of linseed oil and sodium silicate solution obtained an EN 13823:2010+A1:2014 / EN 14915:2013 B-s1,d0 fire classification. Carbonized Scots pine treated with pure linseed oil did not obtain any classification under EN 13823:2010+A1:2014/ EN 14915:2013.