Sofia Knapic

Radial variation of wood density components and ring width in cork oak trees

The radial variation of ring width and wood density was studied in cork oaks (Quercus suber) using microdensitometry. The observations were made in young never debarked cork oaks (30–40 years of age) and in mature trees under cork production (37–60 years of age). The cork oak wood is very dense (mean ring density 0.86 g.cm−3, between 0.79 g.cm−3 and 0.97 g.cm−3) with a small intra-ring variability (mean earlywood density 0.80 g.cm−3 and latewood density 0.90 g.cm−3). The density components decreased from pith to bark more rapidly until the 15th ring, and then only slightly. There were no significant differences in the mean density components between never debarked trees and trees under cork production but their outwards decrease was accentuated in the never debarked trees. The annual growth was high, with a ring width mean of 3.9 mm (4.2 mm in the first 30 years) and the latewood represented 57% of the annual growth.RésuméLa variation radiale de la largeur des cernes et de la densité du bois a été étudiée dans le chêne-liège (Quercus suber) par microdensitométrie. Les observations ont été réalisées dans des arbres jeunes jamais écorcés (âge 30–40 ans) et des arbres en phase de production de liège (37–60 ans). Le bois de chêne-liège est très dense (densité moyenne 0,86 g.cm−3, variant entre 0,79 g.cm−3 et 0,97 g.cm−3) avec une variabilité dans le cerne faible (densité moyenne du bois initial 0,80 g.cm−3 et du bois final 0,97 g.cm−3). Les composantes de la densité diminuent du cœur à la périphérie rapidement jusqu’au 15e cerne, puis plus lentement. Les différences entre valeurs moyennes des composantes de la densité du bois des arbres non écorcés et écorcés ne sont pas statistiquement significatives, quoique la diminution radiale soit plus accentuée dans les arbres non écorcés. La croissance annuelle était élevée avec une largeur moyenne de cerne de 3,9 mm (4,2 mm dans les premiers 30 ans) avec le bois final correspondant à 57 % de la croissance annuelle.

Cork as a building material: a review

This review focuses on cork as a natural, renewable and sustainable construction raw-material. Cork has an unusual combination of properties making it suitable for application in buildings and infrastructures, for example insulation, wear-resistance and durability. The material properties combined with a favourable ecological footprint allow designers, architects and engineers to meet some of the Green Building demands. A summary on cork production, structure, chemistry and properties was made. The processing into cork-based products, for example cork agglomerates and composites, is detailed as well as their properties and applications in construction. The aptitude of cork-based products for compliance with sustainability and energy efficiency criteria is also addressed.

Simulated and realised industrial yields in sawing of maritime pine (Pinus pinaster Ait.)

A sawing simulation software was evaluated by comparison with a real situation in the industrial sawing of maritime pine (Pinus pinaster Ait.) stems. At an operational sawmill sawing yields were measured for the conversion of logs with two sawing patterns: production of boards and production of boards and lumber. The simulation used the WoodCIM® optimisation software with similar sawing set-ups and dimensionally matching virtual logs obtained from cross cutting of 3D mathematical reconstructions of maritime pine stems. The virtual maritime pine stems and the sawing simulation software showed potential to evaluate the impact of raw material and process characteristics on the production performance. The simulated sawing yields corresponded closely to the industrial yields for the production of boards (57% volume yield). For production of lumber and boards, the simulation allowed to obtain a higher volume (45% vs. 53%). The negative impact of resin production on the sawing yields was estimated by comparing the industrial yields of resin tapped trees with matching virtual logs and showed a loss of 11% sawn wood volume, increasing with log diameter. ZusammenfassungEine Simulationssoftware zur Einschnittoptimierung wurde durch den Vergleich mit einem realen Einschnitt von Seekiefernstämmen (Pinus pinaster Ait.) bewertet. Die mit zwei verschiedenen Schnittbildern – Einschnitt von Brettern sowie Einschnitt von Brettern und Bauholz – in einem Sägewerk erzielten Schnittholzausbeuten wurden gemessen.Für die Simulation wurde die WoodCIM® Optimierungssoftware benutzt. Dabei wurden ähnliche Schnittbilder und Abschnitte mit gleichen Durchmessern verwendet. Diese wurden aus virtuell modellierten Seekiefernstämmen erzeugt.Die virtuellen Stämme sowie die Simulationssoftware zeigten die Möglichkeit, den Einfluss des Rohmaterials sowie der Prozessbedingungen auf die Schnittholzproduktion zu bewerten.Die Ausbeuten für den reinen Bretteinschnitt aus der Simulation stimmen genau mit den in der Praxis ermittelten Ausbeuten überein (57% Volumenausbeute). Bei der gleichzeitigen Produktion von Bauholz und Brettern ergibt sich aus der Simulation eine höhere Ausbeute (53% statt 45%).Der negative Einfluss der Harzgewinnung auf die Schnittholzausbeute wurde durch den Vergleich der in der Praxis erzielten Schnittholzausbeute von zur Harzgewinnung genutzten Bäumen mit der von entsprechenden virtuellen Bäumen geschätzt. Dabei zeigte sich ein Ausbeuteverlust von 11%, der sich mit steigendem Stammdurchmesser vergrösserte.

Properties of multilayered sandwich panels with an agglomerated cork core for interior applications in buildings

Four types of sandwich panels with multilayered designs were produced using wood veneer of Aleppo pine as face and inner sheets, and cork agglomerate as core, intended for use in construction as panelling or partition walls in interior applications. These multilayered sandwich panels were characterized regarding static hardness and dimensional stability when facing changes in relative humidity and when subjected to a deformation. The panels showed a considerable increase in dimensional stability and shear strength with the increase of the number of layers. The results suggest that the correct design choice, for example number of inner wood sheets and thickness of cork core layers, allows these sandwich panels to be used as non-structural construction elements such as partition walls.

Performance of Expanded High-Density Cork Agglomerates

AbstractPrototype boards of high-density expanded cork agglomerates (230 and 290  kg m−3) were produced and tested for tensile strength (before and after moisture resistance cyclic tests), hardness, thermal conductivity, and reaction to fire. Increases in tensile strength and dimensional stability were observed with the increase in density. No significant change in thermal conductivity was noticed. The application of a varnish resulted in a noticeable increase in hardness for the higher-density cork agglomerate. Reaction to fire was improved from class Efl to class Cfl. The improvement of properties of expanded cork agglomerates from densification can enhance their application in the building sector.