magistrsko delo
Matjaž Dremelj (Author), Željko Gorišek (Reviewer), Aleš Straže (Mentor), Katarina Čufar (Co-mentor)

Abstract

Raziskali smo izbrane fizikalne lastnosti konstrukcijskega lesa hrasta (Quercus sp.) po staranju. Izbrali smo les od nedavno posekanega do starosti 600 let, iz konstrukcij po Sloveniji. Orientirane odrezke lesa dimenzij 40 x 40 x 5 mm iz notranjih delov tramov smo v ta namen dendrokronološko datirali ter lesu določili gostoto, barvo (vizualno in po CIELab standardu), dimenzijsko stabilnost in sorpcijske lastnosti. Vizualno smo ugotovili, da je starejša hrastova jedrovina temnejša. To smo potrdili tudi z linearnim nižanjem svetlosti barve L* s staranjem lesa. Pri starejšem hrastovem lesu smo po večini potrdili večjo dimenzijsko stabilnost v tangencialni smeri, ter nižjo anizotropijo krčenja in nižji sorpcijski koeficient. V radialni smeri spremembe v dimenzijski stabilnosti lesa niso bile potrjene. Ravnovesna vlažnost hrastovega lesa se je s staranjem na celotnem higroskopskem območju znižala, zmanjšala pa se je tudi sorpcijska histereza. Gostota hrastovega lesa se s staranjem ni spreminjala. Ne glede na starost lesa je gostota naraščala s širino branik ter z večanjem deleža kasnega lesa. Raziskava nakazuje, da imajo velik vpliv na dimenzijsko stabilnost in higroskopnost lesa tudi lokalne razmere, ki delujejo na les v času uporabe.

Keywords

les;hrast;Quercus;staranje;barva;dimenzijska stabilnost;sorpcija;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL BF - Biotechnical Faculty
Publisher: [M. Dremelj]
UDC: 630*814.7
COBISS: 2864521 Link will open in a new window
Views: 1007
Downloads: 268
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Other data

Secondary language: English
Secondary title: Selected physical properties of oak wood from historical constructions
Secondary abstract: We studied selected physical properties of oak (Quercus sp.) timber after aging. We investigated wood of various ages, from recently felled to that felled more than 600 years ago. We obtained it from several locations in Slovenia. Oriented wood specimens of dimensions 40 x 40 x 5 mm from the inner part of the beams were dendrochronologicaly dated. We determined wood density, colour (visual assessment and CIELab standard), dimensional stability and sorption properties. We have visually assessed that the colour of the oak heartwood increased with age. This was confirmed by linear decrease of colour lightness L* with wood aging. Dimensional stability in tangential direction increased, while shrinkage anisotropy and the sorption coefficient decreased with age. Changes of dimensional stability of aged oak wood in radial direction were not confirmed. The equilibrium moisture content of oak wood decreased with aging throughout the whole hygroscopic range, and the sorption hysteresis decreased. The density of oak wood did not change with age. Irrespective of wood age, the density increased with increasing growth ring width and proportion of latewood. The research also confirmed great influence of local conditions on dimensional stability and hygroscopity of wood during its service time.
Secondary keywords: wood;oak;aging;colour;dimensional stability;sorption;
Type (COBISS): Master's thesis/paper
Study programme: 0
Thesis comment: Univ. v Ljubljani, Biotehniška fak., Oddelek za lesarstvo
Pages: IX, 44 f.
ID: 10915461