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The objective of this research was to establish comparatively some relevant features of Turkey oak and sessile oak wood, in order to better understand the drying behavior of these species. The analyzed samples were obtained from freshly harvested trees of the same age, originating from the Southern Sub-Carpathians. The microscopic analysis revealed that Turkey oak has larger earlywood pores than sessile oak. In heartwood, they are partly filled with tyloses for both species. The macroscopic analysis showed that Turkey oak wood has a much lower proportion of heartwood (only 50%) compared to sessile oak (90%). The comparative FTIR analysis of the two species showed similar qualitative chemical composition, but also some differences between sapwood and heartwood regarding the relative proportion of the main constituents, and very likely in the structure of lignin. High amounts of extractives were found in Turkey oak sapwood (5.34% in cold water, 7.77% in hot water, and 21.60% in NaOH 1%), close to the values obtained in sessile oak heartwood. The research also revealed that the Turkey oak sapwood and heartwood have statistically similar values of oven-dry density, shrinkage coefficient, fiber saturation point, while in sessile oak, the values are clearly higher in the heartwood.

Subfossil oak (SO) wood material, originating from three different buried trunks discovered in recent years by excavations in riverbanks on Romanian territory, was analysed in this research. Aged oak recovered from constructions (AO_C) and recent/new oak wood material (NO) were also investigated to provide comparative data for the SO. The oven-dry density and the basic density, the total volumetric and linear swelling and shrinkage coefficients and the compression strength parallel to the grain were the selected physical and mechanical properties considered. The experimental results showed a lower density of SO compared to NO and AO_C tested by up to about 19–20%, alongside a trend of increased dimensional instability, with variability among the tested assortments. The compression strength parallel to the grain was reduced by 19–31% compared to NO. The properties of AO-C were closer to those of NO, but differences between wood materials from different sources and of different ages were registered. A positive linear correlation was found between compression strength parallel to grain and the basic density for all types of material and assortments tested. These comparative results have to be considered by designers and engineers in the valorisation of SO in furniture design and other applications.

The best-possible valorization of each cut log is a priority. The aim of this research was to evaluate the potential of a solution for increasing the conversion efficiency of tapered logs, by edge-cutting the narrowest sideboards at 45° and joining them by gluing, in order to obtain usable lumber boards. The modality of obtaining the glued elements was described and the values of the density and bending properties (MOE and MOR) of these elements compared to solid wood elements taken from the same logs and the same position within each log was determined. The envisaged outcome was to determine if the bonded products are suited to be used as cores within laminated products for construction.

The objective of the research was to study the mechanical properties of recovered solid wood and wood-based materials, to create new panels made of strips of recovered oak and spruce wood, particleboards and blockboards and to study their mechanical properties, feasibility and use. Flatness, MOR and MOE were determined for the solid wood and wood-based materials recovered from construction and demolition sites. Four types of experimental panels (PL1, PL2, PALL1 and PALL2) were manufactured from solid wood strips alternating with either particleboard or blockboard strips glued edge to edge. Some of their physical and mechanical properties were investigated. All new panels made from recovered materials fell within allowable limits specified in European standard requirements for panel flatness. Panels type PL2, PALL1 and PALL2 show better values for MoR and MoE parallel to the grain when compared to the respective values for the recovered wood-based materials of which they are made, but panels type PL1 show no change. Panels type PALL2 are preferable to panels type PALL1 due to better mechanical properties. Panels type PL1 and PL2 show no such differences in their structure. The results also show that these new panels can be used successfully in furniture production, provided panels type PL1, PL2 ad PALL1 do not bear loads perpendicular to the grain or receive reinforcing elements.

The main objective of this study was to find scientific arguments in favour of reusing recovered oak wood in order to reintegrate it in new types of structures. For this study six beams were selected, which had been recovered from a house built in 1831. Visual analysis revealed several defects and signs of degradation in the sapwood and inside the cracks. The recovered beams hadn’t been treated with any toxic chemicals. Bending strength, modulus of elasticity and compression strength parallel to the grain were investigated and microscopy and FTIR-ATR spectroscopy were used to check the quality of the apparently sound beam areas also used for the determination of mechanical properties. Macroscopic and microscopic analysis may not reveal any incipient fungal attack but FTIR analysis was proven to be effective. The obtained results open a new perspective for the future use of recovered old oak wood, due to the adequate mechanical properties and to the assumed means of eliminating degraded areas.

The paper presents the results of anexperimental study performed with black pine (Pinusnigra L.) and spruce (Picea abies L.) wood, originatingfrom mature trees and thinnings cut from the sameparcel from the Stroesti-Arges region in Romania.After air drying and conditioning, the defect-freetest boards were cut into standard 20x20x60mmsamples for the compression test. The compressionstrength was measured and the rupture mode incompression was analyzed.Therefore, the sampleswere first dried to oven-dry state, then heat-treated athigh temperatures (180 and 200ºC) for 1, 2, 3 and 4hours. Sets of 10 samples from each wood species,wood assortment and treating regime were tested.The obtained results were comparativelyanalyzed for the two species (pine vs. spruce) and forthe two wood assortments (mature wood vs, thinwood). Then they were also expressed relatively tothe mass loss, considered to be the main indiactor ofthe degradation suffered by wood during the heattreatment.A graph was drawn for each species andassortment in order to establish the optimum treatingregime, considering the correlated influence of theheat treatment conditions upon all three analyzedproperties (mass loss, dimensional stability andcompression strength).The results of the present research are to bevalorized at the manufacturing of solid wood panelsmade from heat-treated lamellas.

Sessile oak from young trees represents asecondary resource with potential for superiorapplications in furniture panels providing theirdimensional stability to variations of relative airhumidity is reduced. A possibility to improve thisproperty was examined in this paper, by thermaltreatment of the raw material before manufacturingdecorative furniture panels with transversal grain.Panels with crosscut grain were manufactured fromboth heat treated and untreated wood and theirproperties were compared: dimensional changewith climate, the moisture content at equilibrium, theabsolute density, colour and their MOE and MOR.The results have shown that the thermaltreatment at 130ºC for 2h of sessile oak from youngtrees has improved the dimensional stability and theequilibrium moisture content of the panels and didnot impair their mechanical strength. The colour gotslightly darker and density had an almost negligibledecrease by the heat treatment. Attractive bydesign, because of their grain orientation, but in thisway subjected to axial stresses perpendicular to thegrain, the panels could be used in furnitureapplications where the bending stresses are notcritical.

The paper presents the experimental resultsobtained for the shearing strength of black locustwood (Robinia pseudacacia L.) harvested from twogeographical areas (North and South) of Romania.Wood is subjected to shearing stress when usedwithin different fields, and especially inconstructions. Tangential stresses are produced inthe shearing sections and they are influenced by thestructure of wood through the position of theshearing plane and of the force direction towards thegrain. Accordingly, several shearing types arepossible. The shearing strengths for the three mainshearing types, both on radial and tangentialdirection were determined within the present study.The evaluation of data was achieved by using theANOVA analysis, in order to test the level ofsignificance depending on the shearing planeorientation and the harvesting area. The obtainedresults were compared to the values mentionedwithin reference literature for this wood species andtwo other hardwood species with similar density. It isworth to be mentioned that the shearing strengths ofblack locust wood from Romania (both from Northand South) are generally higher than those indicatedby reference literature for oak and beech. Thisrecommends black locust wood as constructionwood and for other applications where wood issubjected to shearing stress.