Natural Durability of Chestnut Wood in Soil Contact: A Comparative Study Across Different Climatic Regions of Türkiye

Structural performance of the finger-jointed strength of some wood species with different joint configurations

This paper deals with softening behaviour measurements of Indonesian wood species by static bending tests. Wood samples with a size of 110mm (R) x 10mm (T) x 4mm (L) were bending tested in air-dry at 20°C and 65% relative humidity (RH), in water saturation at 20°C, and in water saturation at 80°C to know the decreasing of modulus of elasticity (MOE) and modulus of rupture (MOR) due to moisture content (MC) and both moisture content and temperature (MCT) changes. The wood samples represented Randu (Bombax ceiba. L) as the lowest specific gravity, i.e. 0.27 to Lamtoro (Leucaena glauca (Willd) Benth) as the highest specific gravity, i.e. 0.81. The three-point static bending test was carried out by a mechanical testing machine with a load capacity of 100kgf, loading deflection speed of 5mm/min, a span distance of 80mm at a room with a temperature of 20°C and 65% RH for air-dry wood samples, and that for wet wood samples were conducted in a water bath at 20°C (change in MC) and 80°C (change in MCT), respectively. MOE and MOR increased linearly with specific gravity regardless of wood species. On the other hand, maximum deflection did not correlate with specific gravity for any MCT conditions. The relative MOE and MOR which were calculated in wet 20°C to air-dry were affected from hardly to strongly depending on the wood species. Meanwhile, they decreased extremely when saturated in water at 80°C regardless of wood species. The relative MOE and MOR due to the change in MC or MCT was independent of specific gravity, as well. Furthermore, chemical compositions of the wood species were analysed to clarify the main factors that affected the decreasing of MOE and MOR due to MC and MCT changes. The results showed that the percentage of lignin and hemicelluloses in each wood played an important role in decreasing the static bending properties. Relative MOE and MOR decreased with increasing lignin and hemicellulose contents. It can be concluded that the hygrothermal properties of lignin and hemicelluloses significantly affect the changes of elastic and strength properties of wood in softening conditions.

Bu çalışmada farklı rutubet miktarına (RM) sahip (HK-Hava kurusu, LD- Lif doygunluğu ve SD- Suya doymuş) Sarıçam (Pinus sylvestris L.) odununa -70 oC’de sığ kriyojenik işlem (SKİ) uygulamanın ağaç malzemenin eğilme direnci ve elastikiyet modülü özelliklerindeki etkileri araştırılmıştır. Eğilme direncinin (ED) belirlenmesinde TS 2474, eğilmede elastikiyet modülünün (EEM) belirlenmesinde ise TS 2478 esaslarına uyulmuştur. SKİ uygulanması ile örneklerin ED ve EEM üzerinde kayda değer artışlar gözlenmiştir. Ayrıca SKİ uygulamanın ED ve EEM üzerindeki etkisi istatistiksel olarak anlamlı bulunmuştur (p≤0,05). Malzemelerin maruz kaldıkları RM arttıkça ED ve EEM değerlerinin düştüğü görülmüştür. RM’nin ED üzerindeki etkisi istatistiksel olarak anlamlı iken (p≤0,05), EEM üzerindeki etkisi anlamsız bulunmuştur. Çalışma sonucu en yüksek ED (101,16 N/mm2) - 70 oC SKİ uygulanmış HK rutubetindeki örneklerde görülürken en düşük ED (76,05 N/mm2) SKİ uygulanmamış SD örneklerde görülmüştür. Benzer şekilde en yüksek EEM (12629,2 N/mm2) SKİ uygulanmış HK rutubet miktarlı örneklere görülürken en düşük EEM (8759 N/mm2) SKİ uygulanmamış LD rutubet miktarına sahip örneklerde görülmüştür. Sonuç olarak SKİ uygulamanın ağaç malzemenin mekanik özellikleri üzerinde olumlu etkiye sahip olduğu söylenebilir.

Nondestructive evaluation of wood railroad ties was previously investigated using acoustic velocity (AV). Flexural properties, however, have not been well studied among legacy ties as well as new ties of wood species and grades. Therefore, modulus of elasticity (MOE) and modulus of rupture (MOR) from two groups of wood species for three grade conditions were investigated. For similar ties, regression analysis of destructive and nondestructive data was performed. Overall, 60 new on-grade, 40 new off-grade, and 55 Grade 1 legacy ties were examined. The wood species groups were either oak/hickory or mixed hardwood. MOE and MOR of destructive evaluation were obtained, and these were compared with their companion AV value of each tie using polynomial regression analysis. All destructive evaluation data were analyzed using two-way analysis of variance. There was a statistically significant interaction between species and grade for MOR (P < 0.0010), in which new, on-grade oak/hickory ties had a higher MOR compared with mixed wood. Furthermore, a higher MOE (P < 0.0001) was observed for oak/hickory than for mixed wood ties. Additionally, the highest MOE (P < 0.0132) belonged to new on-grade ties, whereas legacy ties had the lowest MOE. A significant relationship was observed between AV free and fixed and with MOE and MOR. These results indicate that both wood species and grade conditions are important factors for determination of strength and stiffness of ties. Additionally, AV could be useful technology for grading new ties and for identifying legacy ties that should be removed from service.

Regression and ANN models for predicting MOR and MOE of heat-treated fir wood

Improvements in the yield and solubility of chestnut wood extractives, by using different extraction methods and molybdenum catalysts as support, have rarely been reported in literature. Many studies focus on the different parts of trees, except for the chemical characteristics of the remaining extractives achieved from thermally modified (THM) chestnut (Castanea sativa Mill) wood. This research seeks to better understand the effects of extraction techniques and catalysts on the yield and solubility of extractives. GC-MS analysis of the chloroform soluble and insoluble fractions was also used. Accelerated Solvent Extraction (ASE) 110 °C, Soxhlet, and autoclave extraction techniques were used to obtain extractives from untreated and thermally modified (THM) chestnut wood (170 °C for 3 h). Ethanol/H2O, ethanol/toluene, and water were the solvents used for each technique. A polyoxometalate compound (H3PMo12O40) and MoO3 supported on silica were used as catalysts. The THM induced a change in the wood’s surface color (ΔE = 21.5) and an increase in mass loss (5.9%), while the equilibrium moisture content (EMC) was reduced by 17.4% compared to the control wood. The yields of the extractives and their solubility were always higher in THM and mainly used ASE as the technique. GC-MS analysis of the extractives, without catalyst support, showed different results for each extraction technique and type of wood (untreated and THM). Ultimately, the amount of extractive compound dissolved in each solvent will differ, and the choice of extraction technique will depend on the intended final application of the extracted chemical product.

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 modulus of elasticity and flexural strength properties of laminated wood elements reinforced with steel mesh with different mesh openings were determined. In accordance with the purpose of the study, three- and five-layer laminated elements were produced from scotch pine (Pinus sylvestris L.) wood material, which is widely used in the wood construction industry in Türkiye. The 50, 70, and 90 mesh steel used as the support layer was placed between each lamella and pressed with polyvinylacetate (PVAc-D4) and polyurethane (PUR-D4) adhesives. Afterward, the prepared test samples were kept for 3 weeks at 20 °C temperature and 65 ± 5% relative humidity for 3 weeks. The flexural strength and modulus of elasticity in flexural of the prepared test samples were determined according to the TS EN 408: 2010+A1 standard by the Zwick universal tester. Multiple analysis of variance (MANOVA) was carried out using MSTAT-C 1.2 software to determine the effect of the modulus of elasticity and flexural strength on the obtained flexural properties, the mesh opening of the support layer, and the adhesive type. When the differences within or between groups were significant with a margin of error of 0.05, achievement rankings were made using the Duncan test on the basis of the least significant difference. According to the results of the research, the highest bending strength (120.3 N/mm2) was obtained in three-layer samples reinforced with 50 mesh steel wire and bonded with Pol-D4 glue, and the highest modulus of elasticity (8969.3 N/mm2) was obtained in three-layer samples reinforced with 50 mesh steel wire and bonded with Pol-D4 glue. As a result, the reinforcement of the laminated wood material with steel wire had an increasing effect on the strength. Accordingly, the use of 50 mesh steel wire can be recommended to increase mechanical properties.

The present study examined the bending moment capacity and rigidity of T-type out-of-plane furniture joints and investigated the effects of heat treatment, wood species, and joint type factors on these joints. Heat treatment method clearly decreased the modulus of rupture (MOR) and the modulus of elasticity (MOE) of selected wood species. The bending strength of wood samples was reduced after the heat treatment, decreasing with increased loss of mass. For the heat-treated T-type joints, maximum bending strength values were obtained with Iroko (Chlorophora excelsa) for both mortise and tenon (MT) joints and blind MT (BMT) joints. The lowest reduction in bending strength was observed in Ash (Fraxinus excelsior L.) constructed with MT joints and with BMT joints. In general, the BMT joint had higher bending strength than MT joints. The best rigidity constant (7.21) was obtained with control Iroko BMT joints, while the worst rigidity constant (15.10) was obtained with control Oriental spruce (Picea orientalis L.) MT joints. In terms of heat-treated samples, the best rigidity constant (7.59) was obtained with Black pine (Pinus nigra L.) MT joints, while the worst rigidity constant (14.01) was obtained with Oriental spruce BMT joints. The maximum performance in joint stiffness was determined for Iroko sample BMT joints and Iroko MT joints. Lowest reduction in joint stiffness was observed in Scotch pine MT joints and Ash BMT joints. Heat treatment, wood type, and joint type had a significant effect on the bending strength of T-type MT post-rail joints. BMT joints produced from heat-treated Iroko wood can be considered as the most durable T-type joint for outdoor sitting furniture construction.

In this study, withdrawal strengths of T-type furniture joints prepared from different wood species and connected with different joint methods were compared. Specimens were constructed of Turkish beech (Fagus orientalis L.), Scotch pine (Pinus sylvestris L.), Sessile oak (Quercus petraea Liebl), Anatolian chestnut (Castanea sativa Mill) and Common Walnut (Juglans regia L.). Dowel and mortise and tenon joints were considered as glued joints, while screwed joint, minifix and maxifix joints were considered as without glue joints. In the glued joints, polyvinylacetate (PVAc) and polyurethane (Pu) adhesives were utilized. A total of 350 specimens that included 5 wood species, 7 joint methods, and 10 replications for each were prepared and tested under static direct withdrawal loads. As a result of the tests, the highest withdrawal strengths were obtained with oak while the lowest withdrawal strengths were obtained with scotch pine and Anatolian chestnut. Mortise and tenon joints were showed the best results while minifix and maxifix joints were yielded the worst among the connection types. For glued joints, PVAc gave higher values than Pu and mortise and tenon joints gave better results than dowel joints.

The most widespread wood species in the Portuguese forest and the most widely utilized are maritime pine (Pinus pinaster) and eucalyptus (Eucalyptus globulus Labill). In the case of eucalyptus, except for the pulping sector, it might have limited usage due to drying issues and low permeability. Microwave (MW) treatment is a technology that has been used to improve wood species’ permeability. Therefore, the present paper aimed to evaluate the MW treatment of both Portuguese wood species and to investigate the effects of different MW treatments on wood’s density, water uptake capability, modulus of rupture (MOR), and modulus of elasticity (MOE). Using small clear wood specimens, two MW powers were used, 700 and 1200 W, and the samples were submitted to successive MW cycles of 2 min till they reached the required dryness. The results showed that each wood species had a different behavior during the MW drying in terms of drying rate, supply, and consumption of energy. In general, with the increase in MW power, the densities of both species decreased and the water uptake increased, as a possible indicator that a certain level of microstructural damage might have occurred. Regarding the mechanical properties of MW-treated maritime pine and eucalyptus wood specimens, under the harshest conditions (MW power of 1200 W), MOR and MOE were reduced compared with the wood sample without MW treatment.

Veneer logs are generally heated in hot water or steam prior to the cutting process in veneering and plywood manufacturing. For economical reasons, the veneers should be dried quickly and without damage. High temperatures shorten drying times. Besides the benefits of log steaming and quick drying of veneers at high temperatures, these processes can be effective on some mechanical, physical and chemical properties of wood. In this study, the effects of the steaming process on logs and veneer drying temperatures on bending strength and modulus of elasticity (MOE) of plywood panels manufactured from spruce and alder veneers were investigated. For this aim, some parts of both wood species logs were steamed for 12 hours before veneer manufacturing while some parts were used unsteamed. Unsteamed and steamed groups of spruce and alder veneers were dried at 20°C, 110°C and 180°C temperatures. The effect of the steaming process on bending strength and MOE was different depending on the wood species. Bending strength and the MOE values of spruce plywood panels increased while both strength values of alder plywood panels decreased after the steaming process. The highest bending strength and MOE values were obtained at 110°C for alder and at 180°C for spruce plywood panels.

The composite material made is a sandwich composite, GRC-mortar. This system is composed of a combination of laminae with others through a wiremesh that binds Styrofoam. This composite system is used as an earthquake-resistant house wall, which is expected to be not only lightweight, but also rigid and strong, the mechanical testing involved is bending testing to determine the bending strength and modulus of elasticity of the variation in mortar massa of 20 kg, 30 kg and 40 kg. the highest bending strength is 0.88 Mpa given massa mortar 20 kg, the lowest bending value is given over a mass of 30 kg, which is 0.79 MPa. The highest modulus of elasticity is 30 kg of mortar mass, which is 0.005 MPa, while the massa of 20 kg and 40 kg of mortar has a modulus of elasticity value of 0.003 MPa respectively. The composite that provides optimal strength is at a mass of 20 kg, in addition to being quite resistant to high bending strength.

Eucalyptus plantations wood have great potential application in high quality solid wood product. In order to improve the overall characteristics, heat treatments (HT) were carried out using Eucalyptus urophylla S.T. Blake wood at 150, 170 and 190 °C, for 2 and 4 h, separately. The effects of HT on physical and mechanical properties, wood color, dimensional stability and chemical change were investigated. The results indicate that: Mass loss (ML) of wood at a moderate temperature of 150 °C was small, but increased remarkably when temperature exceeds 170 °C. A maximum ML of 5.83% was observed at 190 °C/4 h; the velocity of water vapor adsorption and equilibrium moisture content (EMC) of HT wood decreased significantly, and varied considerably with treating severity; absolute dry density of HT wood decreased, presenting a similar tendency with ML, but the reduction was greater than ML; HT reduced the tangential and radial swelling ratio and swelling coefficients of wood, and improved the dimensional stability by 71.88% at 190 °C; modulus of rupture (MOR) and modulus of elasticity (MOE) of HT wood varied significantly in severer conditions, but there were no obvious changes in a moderate conditions at 150 °C; there was a slight color change at 150 °C, but wood color became more dark and uniform with treating severity; HT decreased the relative content of hydroxyl groups in wood components, improving wood dimensional stability. Color change of wood may be caused by variations of chromophoric groups and its own structure of lignin due to HT. Moderate temperature HT at 150 °C improved dimensional stability and color uniform of wood, but without reducing mechanical stress. This is a practical HT condition for Eucalyptus urophylla S.T. Blake.

The aim of the study was to evaluate the optical, mechanical, and microbiological performance of heat-cured polymethyl methacrylate (PMMA) modified by adding various gum Acacia arabica (GA) concentrations.Specimens containing 1, 2.5, 5, 7.5, and 10% GA by weight were prepared, with control specimens containing no GA. Thirty-six rectangular samplings were assessed for color changes, flexural strength, and elastic modulus. Color measurement was conducted using a spectrophotometer. A universal testing machine measured flexural strength through a three-point bending test, and the elastic modulus was calculated. A profilometer and Vickers hardness tester evaluated the surface roughness and hardness. Antifungal activity was assessed by incubating specimens with Candida albicans and counting colony-forming units (CFU/mL).Data were analyzed using the Kruskal-Wallis test for antifungal activity and optical properties and One-way ANOVA for mechanical properties at a significance level of p < 0.05.Groups with higher GA concentrations exhibited significant color changes (p < 0.001). Nonsignificant changes were reported in flexural strength, elastic modulus, or surface hardness (p >0.05), although lower concentrations of GA (1 and 2.5% wt) improved surface hardness. Both 7.5% and 10% wt GA significantly increased surface roughness (p < 0.001). Antifungal activity increased with GA concentration declining from 12 × 108 CFU/mL in the control to no detectable fungal growth in the 10% wt.Low GA concentrations (1 and 2.5%) improved hardness with minimal surface changes, while higher levels (7.5 and 10%) significantly enhanced antifungal efficacy but compromised roughness and aesthetics. A 5% GA concentration offered a balanced compromise, necessitating further investigation.