Search

Bukovina sodi med najpomembnejše lesne vrste v Sloveniji. Standard SIST EN 350-2 uvršča bukovino med lesne vrste z najslabšo odpornostjo proti lesnim glivam. To je eden izmed najpomembnejših razlogov, ki preprečuje uporabo bukovine na prostem. Večina podatkov o odpornosti bukovine temelji na laboratorijskih testiranjih, realnih terenskih testov pa je relativno malo. Življenjska doba bukovine je v veliki meri odvisna od lokalnih podnebnih razmer, zato je nujno določiti življenjsko dobo posameznih lesnih vrst na prostem v osrednji Sloveniji. Na Oddelku za lesarstvo zato že več let potekajo testi, s katerimi določamo odpornost bukovine v tretjem razredu uporabe (na prostem, ni v stiku z zemljo). Prvi znaki glivnega razkroja se pojavijo že po nekaj mesecih izpostavitve, kasneje se razkroj nadaljuje, vzorci pa povsem propadejo po 4 do 6 letih izpostavitve. Glavni razlog za dovzetnost bukovine za glivni razkroj je povezan z odsotnostjo biološko aktivnih snovi (ekstraktivov) in dejstvom, da se bukovina relativno hitro navlaži. Z namenom proučiti dinamiko vlaženja bukovine smo petnajst mesecev stalno spremljali vlažnost lesa v različnih razmerah uporabe. Pričakujemo, da bomo skozi daljše obdobje spremljanja relevantnih lastnosti bukovine, preostalih lesnih vrst in modificiranega lesa pridobili podatke, ki bodo omogočili širšo rabo bukovega lesa na prostem. Beech wood is amongst the most important wood species in Slovenia. The EU standard EN 350-2 classifies beech wood into the group of the least durable wood species. This is one of the most important reasons which limit the use of beech wood in outdoor applications. The majority of the data about beech wood durability is a result of laboratory tests as there were limited numbers of field tests performed. As the service life of wood significantly depends on the local climate conditions, this data cannot be simply copied from other countries. Therefore, field tests have been running at the field test site of the Department of Wood Science and Technology for several years now to determine comprehensive performance of most important Slovenian wood species including beech wood. Majority of the tests are performed in use class 3 applications (above ground, not covered). The first signs of decay on beech wood are visible after few months of exposure. Afterwards the decay proceeds and the samples are degraded between 4 and 6 years of exposure. The most important reasons for insufficient outdoor performance of beech wood are lack of biologically active extractives and low water exclusion efficacy. In order to elucidate this phenomenon moisture content was continuously monitored for 15 months. We believe that the field tests performed will lead us to the data which will enable better understanding of the phenomena of durability and improve durability of beech wood with state of the art modification solutions.

Beech is one of the most important tree species in Slovenia. Unfortunately, there is much more beech wood incremented annually than consumed. Thus, it is of great importance to develop new applications for use of beech wood. One of the possible solutions is use of beech in outdoor applications. However, if beech is used outdoor it has to be somehow protected. In the recent period, non-biocidal methods of wood protection such as thermal modification and use of wax emulsions are gaining more and more importance, hence we applied these two methods to beech wood in present research as well. During the research, water exclusion efficacy of wood was determined. Wood was subjected to various abiotic and biotic degradation protocols. The results exhibited that the best water performance was achieved in wax treated thermally modified beech. Water performance of wax treated wood was not affected by abiotic and biotic degradation factors. By contrast, the aging protocols applied considerably reduced water exclusion efficacy of beech and thermally modified beech wood.

Beech wood is amongst the most important wood species in Slovenia. The EU standard EN 350-2 classifies beech wood into the group of the least durable wood species. This is one of the most important reasons which limit the use of beech wood in outdoor applications. The majority of the data about beech wood durability is a result of laboratory tests as there were limited numbers of field tests performed. As the service life of wood significantly depends on the local climate conditions, this data cannot be simply copied from other countries. Therefore, field tests have been running at the field test site of the Department of Wood Science and Technology for several years now to determine comprehensive performance of most important Slovenian wood species including beech wood. Majority of the tests are performed in use class 3 applications (above ground, not covered). The first signs of decay on beech wood are visible after few months of exposure. Afterwards the decay proceeds and the samples are degraded between 4 and 6 years of exposure. The most important reasons for insufficient outdoor performance of beech wood are lack of biologically active extractives and low water exclusion efficacy. In order to elucidate this phenomenon moisture content was continuously monitored for 15 months. We believe that the field tests performed will lead us to the data which will enable better understanding of the phenomena of durability and improve durability of beech wood with state of the art modification solutions.

Les na prostem je izpostavljen različnim dejavnikom razgradnje, ki so v naravi dobrodošli, v gospodarske namene pa navadno nezaželeni. Baker-etanolaminski pripravki so trenutno najpomembnejša skupina zaščitnih sredstev za zaščito lesa v III. in IV. razredu izpostavitve. Ti pripravki se praviloma dobro vežejo v les, v posameznih primerih pa je opaziti poslabšano vezavo. Le-to pripisujemo neustreznemu kondicioniranju impregniranega lesa. Smrekove vzorce dimenzij (1,5 x 2,5 x 5,0) cm3 (SIST EN 113, 2006) smo impregnirali s komercialnim pripravkom Silvanolinom, 2 različnih koncentracij: 0,25 % Cu in 0,125 % Cu. Preizkušance smo impregnirali v vakuumsko-tlačni komori Kambič. Po končani impregnaciji smo iz dobljenih podatkov izračunali mokri navzem z gravimetrižno metodo in vzorce izpostavili različnim režimom sušenja. Za vsak režim (10 režimov) smo uporabili po 6 vzorcev. Po končanem kondicioniranju je sledilo izpiranje, ki je potekalo v skladu z modificirano standardno laboratorijsko metodo SIST ENV 1250-2. Delež izpranih učinkovin je bil določen po 1. dnevu in po koncu izpiranja iz izpirkov, ki smo jih shranjevali v ta namen. Izpirke smo analizirali z rentgensko flourescenčno spektroskopijo (XRF, Oxford intruments) in atomsko absorpcijsko spektroskopijo (AAS VARIAN SPECTRA AA DUO FS240). Ugotovili smo, da povišana temperatura in visoka relativna vlažnost med kondicioniranjem negativno vplivata na vezavo baker-etanolaminskih pripravkov. V kolikor želimo zagotoviti ustrezno vezavo omenjenih zaščitnih sredstev v les, je najbolje, da jih po končani impregnaciji izpostavimo zmernemu sušenju na prostem, pri čemer ne smemo izpostavljati zaščitenega lesa previsokim temperaturam in spreminjajočim se vremenskim pogojem. Wood in outdoor applications is susceptible to decay and degradation caused by various factors, and although this process might be important in carbon cycle, it is much less desirable phenomenon when wood is used in commercial applications. Copper-ethanolamine based wood preservatives are currently the most important group of preservatives for protection of wood in use classes III and IV. Fixation of these wood preservatives is generally good, although in some cases a decreased fixation can be noticeable. The main reason for this occurrence is presumably unsuitable conditioning of impregnated wood. In the research, spruce wood specimens with dimensions (1.5 x 2.5 x 5.0) cm3 (EN 113, 2006) were impregnated with the Silvanolin commercial solution of 2 different concentrations (0.25 % Cu and 0.125 % Cu). Impregnation of the specimens was performed in a vacuum-pressure chamber, and afterwards retention was determined gravimetrically. After the impregnation, the specimens were exposed to 10 different drying procedures. For each drying procedure 6 specimens were used. Afterwards, the specimens were leached according to the modified standard method ENV 1250-2. After the first and the last day of leaching, the amount of ingredients in leachates was analyzed withX-ray fluorescence spectroscopy (XRF, Oxford instruments) and atomic absorption spectroscopy (AAS VARIAN SPECTRA AA DUO FS240). The results showed that increased temperatures and high relative humidity during conditioning negatively influenced the fixation of copper-ethanolamine preservatives. In order to provide a proper fixation of afore mentioned preservatives in wood, it is suggested to expose them to moderate drying in the open air after impregnation, whereby the preserved wood should not be exposed to too high temperatures and oscillating weather conditions.