Wood is a natural material widely utilized in the forest industry and furniture sector, valued for its aesthetics and durability. Various methods have been developed to extend its service life and protect it against deterioration. In this study, liquid nitrogen treatment was applied to increase retention levels, and the effects of retention and impregnation agents on the mechanical properties of oak wood were examined. Oak (Quercus robur), a species known for its low permeability and difficulty in impregnation, was selected as test samples. The samples were exposed to liquid nitrogen for 15 minutes, 90 minutes, and 6 hours, and subsequently impregnated with Tanalith-E, Imersol Aqua, Diammonium Sulphate, and Borax using brush application, short- and long-term immersion, and pressure methods. Retention levels were determined, and mechanical performance was assessed through compression parallel to the fibers and dynamic bending (impact) resistance tests. The maximum retention value was found to be 4.212 kg/m³ in the long-term immersion method with Borax and a 519% increase in retention rate was obtained. The results showed that liquid nitrogen application increased retention in oak wood and due to this increase, changes in compressive strength and impact strength were observed parallel to the fibers.

In this study, a total of 60 chestnut (Castanea sativa Mill.) wood samples were exposed to soil contact conditions for a period of three years in accordance with the EN252 standard. The tests were conducted in four provinces of Türkiye-Trabzon, Muğla, Çanakkale, and Elazığ-representing the Blacksea, Mediterranean, mixed, and terrestrial climate zones, respectively, in order to assess the natural durability of the wood under different environmental conditions. Climatic indices, soil characteristics, visual decay, mass loss, density, bending strength, modulus of elasticity, compressive strength, and color change were investigated. Among the four locations, the lowest average visual decay rating was observed in chestnut wood Elazığ (1.0), while the highest was recorded in this species of wood in Çanakkale (3.6). Similarly, the greatest weight loss occurred tested wood in Çanakkale, reaching 35.96%, whereas wood in Elazığ exhibited the least mass loss at 4.71%. Regarding density, wood in Elazığ presented the highest value at 0.54 g/cm³, whereas wood in Çanakkale showed the lowest at 0.39 g/cm³. The highest bending strength was wood in Elazığ at 71.73 N/mm2, the lowest was wood in Çanakkale at 38.28 N/mm2. The highest elastic modulus was wood in Elazığ at 5965.89 N/mm2, the lowest was wood in Çanakkale at 3855.42 N/mm². The highest compressive strength parallel to fibers (underground and aboveground) was wood in Elazığ at 48.25 N/mm² and 50.87 N/mm², respectively; the lowest was wood in Çanakkale, 13.51 N/mm² and 40.59 N/mm², respectively. The most significant color change was observed in the chestnut wood in Trabzon.

This paper examines the climate impacts of using wood and wood-based products in construction, focusing on their carbon sequestration potential, life cycle emissions, and end-of-life scenarios. The analysis is based on Environmental Product Declarations (EPDs) and scientific literature, in accordance with LCA standards such as EN 15804 and ISO 14040. Three forest management strategies—long-rotation forestry, short-rotation plantations, and continuous cover forestry—are compared in terms of their carbon storage efficiency. The study highlights significant differences in greenhouse gas emissions between solid wood and engineered wood products, particularly in the A3 module due to processing intensity. End-of-life scenarios (C1–C4) and benefits beyond the system boundary (D module) have a major influence on the total GWP, with reuse and recycling offering the most favorable outcomes. Incineration with energy recovery partially offsets emissions but eliminates the biogenic carbon storage benefit. Dynamic LCA approaches are recommended for a more accurate assessment of temporal carbon flows. Harmonisation of methodologies across EPDs is essential for credible comparison. The findings support increased use of sustainably sourced wood in construction, provided that product design enables reuse, disassembly, and integration into circular material streams.

The paper investigates an assessment of mechanical strength in relation to dynamic and static MOE of Antrocaryon micraster stemwood from the semi-deciduous ecological zone in Ghana. The objective was to assess the strength variation of Antrocaryon micraster stemwood along the axial direction, using destructive and non-destructive methods. Antrocaryon micraster stemwood that was divided into bottom, middle and top positions were prepared for the study. The results reveal that the stemwood bottom position obtained maximum density (530.43 kg/m³) representing 10% and 16.02% higher when compared to other corresponding positions (middle and top) respectively. For stemwood along the axial direction, the static MOE mean values were 18.54%, 22.82%, and 27.48% more than the dynamic MOE obtained in the bottom, middle and top positions, respectively. At 1% and 5% levels of significance, the position of the stemwood along the tree height has a significant effect on dynamic MOE and static MOE. Statistical evaluation with regression and Pearson correlation also indicates positive relationship with the variability of 50.4% and 71%, respectively. In a whole, the mechanical behaviour of the Antrocaryon micraster stemwood, especially the bottom position along the axial plane is considered wealthy to be selected for furniture applications.

High-density fiberboard (HDF) has been utilized in various forest-based industries for centuries. This study investigated the effects of different adhesive ratios on the properties of HDF through a series of tests. The panels, designed in particular for this examine, had been produced in a laboratory putting the usage of a combination of 70% fir (Abies nordmanniana subsp. bornmulleriana) and 30% beech (Fagus orientalis L.) fibers sourced from the western Black Sea area of Turkey. Two adhesive levels were tested: 10.73% for Panel - I and 11.30% for Panel - , both calculated based on dry fiber weight. We assessed several physical and mechanical properties, including density, modulus of rupture (MOR), modulus of elasticity (MOE), internal bonding (IB), hardness, water absorption, and through-thickness swell, in accordance with standard testing methods. The results indicated that both adhesive levels produced panels meeting the general performance requirements for HDF. Panel II, which contained slightly more adhesive, demonstrated marginally better performance in specific strength and dimensional stability tests. Overall, the findings suggest that optimizing adhesive usage in industrial HDF production can help establish a balance between the performance requirements of the boards and cost-effectiveness in production.

The growing demand for wood as a raw material, coupled with the impacts of climate change on coniferous forests, necessitates research into underutilized wood species and potential hardwood alternatives. By integrating material characterisation with computational analysis, this research aims to bridge the gap between resource availability and structural performance. This study focuses on developing a numerical model to simulate the mechanical behavior of softwood, hardwood, and hybrid cross-laminated timbers (CLT) under bending loads within the linear elastic range. The research methodology involved finite element analysis to simulate four-point bending tests on hybrid CLT panels using the open-source FEM solver Code_Aster. Material properties were determined based on Non-Destructive Test (NDT) measurements and literature data. The developed finite element model successfully simulated CLT’s response under four-point bending conditions, demonstrating its potential for virtual prototyping of various underutilized wood species in CLT applications. The numerical model showed acceptable agreement with experimental results. The relative error varies between 1.30% to 17.37% in the results based on the NDT measurements. The results derived on literature values show higher variation. This computational approach provides a valuable tool for evaluating alternative wood species in engineered wood products.

As a cornerstone structural material in Chinese architectural heritage, understanding the long-term durability of Chinese fir (Cunninghamia lanceolata) is critical for its preservation. This study comparatively investigates the degradation of Chinese fir under three accelerated aging protocols simulating key environmental threats: ultraviolet (UV) weathering, thermal-humidity cycling, and salt fog. The results revealed distinct degradation mechanisms with significant implications for heritage diagnostics. Salt fog exposure induced the most severe degradation, causing a 63.9% loss in bending strength through comprehensive chemical attacks. UV weathering led to significant surface photodegradation and microcracking, while thermal-humidity cycling caused a 46.5% reduction in bending strength, primarily due to physical stresses. Crucially, a strong, universal correlation was established between cellulose crystallinity (CrI) and the mechanical properties (tensile, R = 0.874; compressive, R = 0.902; bending, R = 0.941) across all aging conditions. This identifies CrI as a robust and minimally invasive indicator for assessing the mechanical integrity of historic timbers. Furthermore, the degradation kinetics under each stressor followed highly predictable linear trends (R² > 0.89), providing a quantitative basis for developing targeted conservation strategies and more accurate service life prediction models for timber heritage structures.

The first part of the study (Natural Durability of Some Wood Species in Ground Contact at Four Sites in Turkey Part 1: The Physical Properties) was published in the 67th volume of Drewno. This study involved the examination of heartwood, sapwood, and CCB (Copper Chromium Boron) impregnated sapwood samples from various tree species including Scots pine (Pinus sylvestris L), Caucasian spruce (Picea orientalis (L.) Peterm), European beech (Fagus orientalis L.) and common alder (Alnus glutinosa subsp. barbata), which had 20x20x300 mm dimensions. These samples were subjected to soil contact, specifically in hazard class 4 conditions as defined by EN 252 (2014), for a duration of 3 years. The study was conducted in four different provinces of Turkey, namely Trabzon, Muğla, Çanakkale, and Elazığ, each characterized by distinct climatic conditions. Bending strength, modulus of elasticity and compression strength of the samples collected back from test sites were examined. The highest bending strength, modulus of elasticity and the highest compression strength were observed in Elazığ (dry climate). In Çanakkale, Muğla and Trabzon (humid climate), relatively lower values were recorded. In terms of climate type, it can be said that Scots pine and Caucasian spruce wood samples have higher resistance than the European beech and common alder samples. Especially the heartwood of coniferous has been found to be more durable than the sapwood. In addition, no deformation was observed in any of the impregnated wood samples. The durability of all treated wood samples met the minimum requirements for (soil/outdoor/contact etc.).

In this study, the electrical and dielectric properties of maple wood (Acer trautvetteri Medw.) were comprehensively investigated under three different surface conditions: untreated control (CW), two-week water immersion (SW), and double varnish (VW), as well as a function of frequency. For the accuracy of electrical analysis, all test samples were evaluated in dry state and comparative analysis was performed between surface treatment groups. In the experimental analyses in the frequency range from 100 Hz to 1 MHz, reel/imaginary part of dielectric permittivity (ε′ and ε″), dielectric loss factor (tanδ), alternating current electrical conductivity (σac), specific heat capacity (C), conductivity-dependent free energy component (G/ω), and real (Z′) and imaginary (Z″) impedance components were comprehensively evaluated. According to the test results, the SW test samples, with their high (ε′) and (ε″) values, were found to provide significant ionic and dipolar contributions. However, due to their high (tanδ) and (σac) values, their energy storage capacity is limited, and their conductivity potential is high. The VW test samples, with their low (ε″) and (tanδ) values, exhibit strong insulating properties, making them suitable for high-frequency capacitive applications. The CW test samples, in contrast, exhibit a balanced conductivity-insulation profile with moderate dielectric response. Impedance analyses (Z′, Z″) revealed that the low-resistance ion transport mechanism dominates in the SW test samples, while the surface coating creates a high-resistance barrier, thus limiting charge transport in the VW test samples.

The aim of the study was to assess the hardness and compressive strength of oak wood from various historical contexts, and to compare these properties with modern oak wood. The study utilized both radiocarbon and dendrochronological dating to determine the age of the wood. A total of five oak wood fragments analyzed i.e. bog oak, oak wood from the bell tower of the Collegiate Basilica of the Holy Spirit in Przeworsk; oak wood from the scaffolding of the St. Nicholas Church in Gniew, wood from a dismantled granary in Drawsko Pomorskie and sample from a water dam in Czaniec. The dating confirmed that the oak fragments varied in age, ranging from several centuries to over 900 years. The mechanical tests using the Brinell method and compressive strength tests indicated that wood of bog oak displayed statistically significant differences in compressive strength compared to the other wood samples, which could be attributed to the long-term mineral saturation of the wood from prolonged exposure to anaerobic conditions in the bog. This mineralization likely caused a reduction in its elasticity and overall strength. In contrast, other samples, which had been exposed to varying environmental conditions like periodic water immersion or protection from moisture, did not show significant differences in mechanical tests. Despite these challenges, the findings suggest that compressive strength could serve as a useful indicator for estimating the age of oak wood in archaeological contexts, particularly for assessing the influence of long-term environmental conditions on wood properties.