Influence of selected environmental factors on moisture dynamics of beech wood

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

Influence of selected environmental factors on moisture dynamics of beech wood

Bukovina sodi med najpomembnejše lesne vrste v Sloveniji. Žal uporaba bukovine zelo zaostaja za prirastkom, zato je treba nujno razviti dodatne aplikacije za rabo bukovega lesa. Ena izmed neizkoriščenih priložnosti je tudi raba za manj zahtevne konstrukcije na prostem. V primeru, da uporabljamo bukovino na prostem, moramo les na takšen ali drugačen način zaščititi. V zadnjem obdobju vedno bolj pridobiva na pomenu termična modifikacija in uporaba voskov, zato smo ti dve rešitvi uporabili tudi v tej raziskavi. Tako smo odpornost bukovine na navlaževanje spremljali v laboratorijskih razmerah in terenskih testih. Pred laboratorijskimi poizkusi smo vzorce izpostavili različnim abiotskim in biotskim dejavnikom razkroja ter določili njihov vpliv na navzemanje vode v les. Izkazalo se je, da se je najbolje obnesel termično modificiran les, impregniran s suspenzijo naravnih voskov. Po drugi strani so abiotski in biotski dejavniki razkroja močno poslabšali odpornost proti navlaževanju bukovine in termično modificirane bukovine.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

Selected properties of one hundred year old beech wood

Changes of wood due to ageing are elucidated in this respective article. Beach wood degraded by white rot fungi and furniture beetle was examined. The results of the mechanical tests showed considerable decrease that did not influence on the short term water uptake. Natural durability of old beech wood even decreased what lead us to conclusion that special consideration should be given to the use condition

Service Life of Beech Wood in Outdoor Applications

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

Service life of beech wood in outdoor applications

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

Model za določanje življenjske dobe lesa listavcev

The majority of Slovenian wood species do not have durable wood. Due to increased environmental awareness, users are avoiding treated wood and wood from tropical forests. In order to increase the consumption of domestic wood species, we have to understand the overall performance of wood better. Therefore, a study of the most important Slovenian hardwood species was performed, as prescribed by Meyer-Veltrup et al. Durability against wood decay fungi and wetting was determined using standard laboratory tests. These data were then used for calculation of the respective factors needed for calculation of predicted service life

The effect of natural aging on the selected properties of wood of Norway spruce and sweet chesnut

Les vedno bolj pridobiva na pomenu. Ker bo lesa predvidoma že okoli leta 2020 pričelo zmanjkovati, ga bomo vedno pogosteje reciklirali ali tudi ponovno uporabljali. Želeli smo določiti vpliv naravnega staranja na izbrane lastnosti smrekovine in kostanjevine. Uporabili smo več 10 let star kostanjev drog (Castanea sativa) in 6 let star smrekov nosilec (Picea abies). Staremu lesu smo določili odpornost na glive, pri čemer smo uporabili izolate 5 različnih gliv razkrojevalk lesa: Gloeophyllum trabeum, Antrodia vaillantii, Hypoxylon fragiforme, Pleurotus ostreatus in Trametes versicolor. Mehanske lastnosti smo določali s tritočkovnim upogibnim testom (modul elastičnosti) in tlačnim obremenjevanjem vzorcev. Spremembe v navzemu vode smo določevali na tenziometru. Zanimal nas je tudi delež ekstraktivov v lesu, pri čemer smo za izpiranje uporabili 3 različna topila: vodo, 70 % metanol in cikloheksan. Numerično smo ovrednotili barve staranega lesa po CIE – L*, a*, b* sistemu. Rezultati testiranj kažejo na to, da se relevantne lastnosti kostanjevine niso bistveno spremenile. Tudi po več desetletjih rabe je les ohranil odpornost proti glivam razkrojevalkam lesa, za razliko od lesa smreke. Pri kostanju so prav tako opazne ohranjene mehanske lastnosti in nizek kapilarni navzem vode. Pri ekstrakciji se je kot najučinkovitejše topilo izkazala voda, tako pri kostanjevini in smrekovini. Po drugi strani se je 6 let stara smrekovina izkazala za manj odporno lesno vrsto, z višjo izgubo mase, večjim kapilarnim navzemom vode in manjšim deležem ekstraktivov. Obe lesni vrsti sta z leti spremenili naravno barvo lesa, ki s starostjo potemni.Wood is more and more important material. Since the availability of wood will presumably be scarce by year 2020, it will be more frequently reused and recycled. We tried to determine the effect of natural ageing on the selected properties of spruce and chestnut. The tested wood was a several decades old chestnut pole (Castanea sativa)and a 6 year old spruce beam (Picea abies). The resistance to the different wood decay fungi: Gloeophyllum trabeum, Antrodia vaillantii, Hypoxylon fragiforme, Pleurotus ostreatus, and Trametes versicolor was determined. Mechanical properties were measured by a 3-point bending test (modulus of elasticity) and compressive strength of samples. Changes in water uptake were defined with the use of tensiometre. Extractives in wood were determined by using 3 different solvents: water, 70 % methanol, and cyclohexane. The colour of the aged wood was numerically evaluated by the CIE L*, a*, b* system. The test results show that the relevant properties of chestnut did not change significantly. In comparison to the spruce, even after several decades of use, wood kept the resistance against the wood decay fungi. Preserved mechanical properties and low capillary water uptakewere also observed with chestnut. The most effective solvent for extraction is water, the same with chestnut and spruce. On the other site the 6 year old spruce has turned out to be a less susceptible wood species, with higher weight loss, higher water capillary uptake, and lower amount of extractives. Over the years, the both wood species changed natural colour which turned darker with age

Influence of conditioning on fixation of copper-ethanolamine preservatives

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

Influence of Artificial and Natural Weathering on the Moisture Dynamic of Wood

Wood that is used in outdoor applications is frequently exposed to weathering and is thus prone to fungal degradation. Ways to prevent fungal degradation include keeping the wood dry. The majority of hydrophobic and wood modification systems have been tested only on freshly treated wood. Little information is available on how various wood-based materials perform after a certain period of weathering. To elucidate this question, 17 wood samples were tested from the following species: oak (Quercus), sweet chestnut (Castanea sativa), European larch (Larix decidua), Scots pine heartwood and sapwood (Pinus sylvestris), Norway spruce (Picea abies), and beech (Fagus sylvatica). Moisture performance of the wood samples was improved with thermal modification, wax, oil, and biocide treatment. Specimens were exposed to various degradation-aging factors (blue stain fungi, decay fungi, artificial weathering, and natural weathering). Various moisture performance tests were applied before and after aging: short-term water uptake (tensiometer), long-term water uptake, water vapor tests, drying tests, etc. The water exclusion efficacy of wood was decreased after aging. Aging factors were found to act synergistically and to have a more prominent influence on less durable wood compared to durable or preservative-treated wood. Wax-treated wood performed best, regardless of which moisture performance test was applied