Search

V zadnjem obdobju se raba lesa veča, še posebno za gradbene namene. Na prostem je les izpostavljen delovanju biotskih in abiotskih dejavnikov razkroja. Teh procesov ne moremo preprečiti, s pravilnim načrtovanjem konstrukcij, izbiro ustreznih lesnih vrst ali biocidno zaščito pa jih lahko zelo omejimo. Pri izbiri lesa je eden od najpomembnejših podatkov njegova naravna odpornost. Letos je bil objavljen nov standard, ki na tem področju prinaša številne novosti. Najbolj izrazito je zmanjšanje odpornosti macesnovine in hrastovine, predvsem zaradi variabilnosti lesa, ki je v celoti ne znamo pojasniti. V tem prispevku so navedena najnovejša spoznanja in nekateri rezultati, ki se nanašajo na naravno odpornost in življenjsko dobo lesa. The use of wood is increasing in the recent years, predominately in the building sector. Wood in outdoor applications is exposed to a variety of biotic and abiotic degradation factors. These processes cannot be completely prevented, but can be slowed down with proper construction, selection of wood species and/or application of biocides. One of the most important criteria that influences the selection of wood species is natural durability. There has been new EN standard published recently that brings new classification of wood species to durability classes. The most important decrease of durability has been assigned to larch and oak wood, predominately due to the huge variability that cannot be fully controlled. In the respective contribution, new aspects and data that are related to durability and service life of wood are presented.

The use of wood is increasing in the recent years, predominately in the building sector. Wood in outdoor applications is exposed to a variety of biotic and abiotic degradation factors. These processes cannot be completely prevented, but can be slowed down with proper construction, selection of wood species and/or application of biocides. One of the most important criteria that influences the selection of wood species is natural durability. There has been new EN standard published recently that brings new classification of wood species to durability classes. The most important decrease of durability has been assigned to larch and oak wood, predominately due to the huge variability that cannot be fully controlled. In the respective contribution, new aspects and data that are related to durability and service life of wood are presented. V zadnjem obdobju se raba lesa veča, še posebno za gradbene namene. Na prostem je les izpostavljen delovanju biotskih in abiotskih dejavnikov razkroja. Teh procesov ne moremo preprečiti, s pravilnim načrtovanjem konstrukcij, izbiro ustreznih lesnih vrst ali biocidno zaščito pa jih lahko zelo omejimo. Pri izbiri lesa je eden od najpomembnejših podatkov njegova naravna odpornost. Letos je bil objavljen nov standard, ki na tem področju prinaša številne novosti. Najbolj izrazito je zmanjšanje odpornosti macesnovine in hrastovine, predvsem zaradi variabilnosti lesa, ki je v celoti ne znamo pojasniti. V tem prispevku so navedena najnovejša spoznanja in nekateri rezultati, ki se nanašajo na naravno odpornost in življenjsko dobo lesa.

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 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.