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This study investigated the mechanical properties of beech (Fagus sylvatica L.) and fir (Abies alba) wood from Bosnia and Herzegovina under outdoor exposure. Samples were exposed for 3-month exposure to assess bending strength, color changes, and surface quality. Results showed outdoor exposure negatively affected mechanical properties, particularly in samples with extended finger joints, causing significant surface cracks in uncoated samples. Beech wood exhibited notable color changes under exposure, with approximately 50% darkening without coating compared to 25% under covered conditions. Coated samples displayed minimal color changes, affirming the efficacy of surface treatment. Fir wood exhibited a roughness of 8.264 μm, while beechwood average roughness increased from 6.767 to 13.916 μm after exposure, with micro-pore development affecting water performance. Microscopic analysis identified prevalent fungal colonies, including Penicillium, Aureobasidium, Sclerophoma, and Chaetomium, underscoring their role in organic matter decomposition. This study highlights the importance of wood exposure and treatment selection for various applications. [ABSTRACT FROM AUTHOR]

To improve the resistance of wood to biological decay the Maillard reaction between introduced amines and wood cell-wall polymers can be utilised. However, initial studies in wood modification showed almost complete leaching of bicine and tricine from treated wood and the loss of beneficial effects. The objective of this study was to assess whether possible reactions of bicine or tricine with wood could be further enhanced and reaction products stabilised through the addition of glucose and/or citric acid. Thus, Scots pine sapwood specimens were impregnated with tricine or bicine, with or without glucose and citric acid, and then heated to a temperature of 160°C. The dimensional stability, degree of chemical leaching and mechanical properties were assessed. Overall, it was concluded that neither the presence of glucose nor citric acid did appear to enhance the reactivity of tricine or bicine. Anti-swelling efficiency (ASE) of 50% was observed for combined treatments of bicine/tricine and citric acid but the leaching resistance originated mainly from citric acid and glucose, with no indication for the retention of bicine or tricine. The presence of citric acid led to a strongly reduced modulus of rupture. [ABSTRACT FROM AUTHOR]

The demand for construction timber is continuously increasing, due to its favourable characteristics. However, the adequate protection of wood is key to its successful use, as it is flammable and susceptible to biodegradation. Given that thermal modification enhances the durability of wood, and mineralisation with CaCO3 considerably improves its fire properties, it is worth considering the combined effects of the two methods. European beech (Fagus sylvatica) was selected to determine the effects of a) thermal modification, b) mineralisation through the in-situ formation of CaCO3, and c) a combination of the two procedures, on resistance to decay fungi, reaction to fire and the mechanical properties of the wood. Microscopic analysis and comparisons of the samples before and after exposure to fungi were also conducted. Mineralised wood generally had a slightly alkaline pH value and higher equilibrium moisture content, while thermal modification lowered the equilibrium moisture content. The present study demonstrated the combined effect of thermal modification and mineralisation: the best response to fire as well as resistance to fungi was achieved when the two treatments were combined. Results from the Brinell hardness and three-point bending tests indicate that both modification procedures can slightly impair the mechanical properties of the wood. [ABSTRACT FROM AUTHOR]

When wood is thermally modified, several chemical reactions take place that change the chemical and physical properties of the wood. These changes correlate with the degree of modification, which is mostly a function of the temperature and duration of modification, and consequently with the mass loss during this process. There is a lack of standardised quality control to verify the degree of heat treatment of wood and thus its quality. One of the possible methods to check the degree of thermal modification of a particular type of wood is thermogravimetry (TG). It is based on the assumption that processes that did not take place during thermal modification continue when the TG experiment is carried out. In this method, calibration curves have to be established based on TG measurements of standard samples that have been thermally modified at different temperatures and whose mass loss during modification is known. The calibration curves show the mass loss during the TG measurement as a function of the mass loss during the previous thermal modification. The course of thermal decomposition during the TG measurements is influenced by many parameters, such as the mass of the sample, the heating rate, the atmosphere in which the measurement takes place, and the shape of the crucible in which the sample is placed. In this paper, the influence of these parameters on the calibration curves was investigated. We have focused on oak wood. The best parameters result in a calibration curve with the largest correlation coefficient R2 and the highest slope of the line k. On this basis, we can determine the mass loss during the thermal modification of unknown samples of the same wood species under the same measurement conditions. [ABSTRACT FROM AUTHOR]

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This study aimed to investigate the water absorption capacity of thermally modified and non-modified spruce and blue-stained spruce wood. The wettability of wood depends on various factors, including its type, density, porosity, and surface treatment. Wood can swell and become distorted when exposed to water or humidity, impacting its structural integrity. Hence, it is crucial to consider the water and water vapour uptake in the wood when choosing materials for applications that are likely to be exposed to moisture. Various moisture absorption tests were conducted to assess water absorption capacity, including short-term and long-term water absorption and water vapour absorption. The results showed a significant difference in the long-term exposure to water, which was related to the density of the wood. The study examined the influence of thermal treatment on the physical properties of wood and observed significant variations in mass change due to coating, indicating differences in adhesion among different wood types. Vacuum-treated blue-stained Norway spruce demonstrated higher adhesion (5%-15%) compared to air-treated samples. Furthermore, cohesion tests revealed lower cohesion force in blue-stained Norway spruce (approximately 20%-30%) compared to Norway spruce. The study also used industry-standard tests to investigate the adhesion and cohesion of nano-coatings on wood surfaces. The results provided valuable information on the properties of coatings applied to wood, which is vital in protecting and decorating wood while also providing preventive protection against wood pests, weathering, and mechanical influences. Wood modification in vacuum involves subjecting the wood to a low-pressure environment to remove air and moisture, allowing for deeper and more uniform penetration of treatment chemicals. In contrast, wood modification in air relies on the natural circulation of air to facilitate the absorption of chemical treatments, without the need for a vacuum chamber. [ABSTRACT FROM AUTHOR]

The durability against decay organisms is an essential material property for wood in outdoor use. A jack of all trades method for above-ground wood durability testing has been sought for decades, but until now no method has found its way into European standardization. The method of choice shall be applicable for untreated and treated wood—ideally also for wood composites. It shall further be reproducible, objective, fast, easy, and inexpensive. Finally, it shall provide high predictive power. This study was aimed at a review of results and practical experience with the Bundle test method which could serve as a standard procedure for above-ground field tests of wood-based materials. The method allows for water-trapping, creates a moderate moisture-induced decay risk typical for UC 3 situations, and was found applicable for a wide range of wood materials. The method allows for rapid infestation and failure of non-durable reference species within five years in Central Europe. Based on results from Bundle tests with different modifications and performed at different locations, a guideline has been developed. The method is recommended as a suitable tool for determining the durability of various wood-based materials including modified and preservative-treated wood and can provide data for durability classification. [ABSTRACT FROM AUTHOR]

In this study, the mechanical characteristics of Norway spruce wood (Picea abies) from Bosnia and Herzegovina were investigated by thermal treatment at three different temperatures (specifically, 180, 190, and 210°C) and treatment durations (namely, 2, 3, and 4 hours). For this purpose, the maximum 4-point bending force, the modulus of elasticity in bending, the compression strength parallel to the grain, and the compression strength perpendicular to the grain in treated and untreated specimens were evaluated. Results indicated that the relationship between temperature and duration modification affects the mechanical properties of wood specimens. The results revealed that the relationship between temperature and duration modification influenced the mechanical properties of the wood samples. Specifically, in terms of compression strength, it was observed that the heattreated specimens exhibited improved mechanical properties compared to the unmodified specimens. However, for the maximum 4-point bending force and modulus of elasticity, the results indicated a decrease in mechanical properties. [ABSTRACT FROM AUTHOR]

In this paper, the natural durability of commercial wood (beech wood) was studied by measuring its water exclusion efficacy and durability against fungi. This information was utilized in the Meyer-Veltrup model to calculate the resistance dose. The results showed that Fagus orientalis (Lipsky) heartwood and sapwood were less durable (DC 4-5). After one hour of immersion, the water uptake in F. orientalis sapwood was 19%, slightly more than that determined with F. orientalis heartwood (18.9%). Water immersion after 24 h was highest for F. orientalis sapwood (45.4%), followed by F. orientalis heartwood (40.9%). Up to 54.2% median MLF on F. orientalis heartwood and up to 61.1% median MLF on F. orientalis sapwood were attributed to the white fungus T. versicolor. In contrast, the lowest median MLF was caused by F. orientalis heartwood and sapwood by the white fungus H. fragiforme. 35.4% median MLF on F. orientalis was caused by terrestrial microcosms. Based on the resistance model, the first signs of fungal decay on F. orientalis heartwood and sapwood wood will develop after 312 and 294 days of favorable conditions, respectively. [ABSTRACT FROM AUTHOR]