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The demand for construction timber is continuously increasing, due to its favourable characteristics. However, the adequate protection of wood is key to its successful use, as it is flammable and susceptible to biodegradation. Given that thermal modification enhances the durability of wood, and mineralisation with CaCO3 considerably improves its fire properties, it is worth considering the combined effects of the two methods. European beech (Fagus sylvatica) was selected to determine the effects of a) thermal modification, b) mineralisation through the in-situ formation of CaCO3, and c) a combination of the two procedures, on resistance to decay fungi, reaction to fire and the mechanical properties of the wood. Microscopic analysis and comparisons of the samples before and after exposure to fungi were also conducted. Mineralised wood generally had a slightly alkaline pH value and higher equilibrium moisture content, while thermal modification lowered the equilibrium moisture content. The present study demonstrated the combined effect of thermal modification and mineralisation: the best response to fire as well as resistance to fungi was achieved when the two treatments were combined. Results from the Brinell hardness and three-point bending tests indicate that both modification procedures can slightly impair the mechanical properties of the wood. Nasl. z nasl. zaslona. Opis vira z dne 6. 7. 2023. Bibliografija.

The sorption properties of wood have a characteristic influence on some of its properties, such as the mechanical properties and susceptibility to fungal decay. Moist wood is more susceptible to fungal decay, and wood is often impregnated in order to protect it from fungal decomposition, photodegradation or fire. In particular, inorganic salts affect the sorption properties of wood. For this purpose, the sorption properties of Norway spruce wood impregnated with Burnblock refractory (uptake 38 kg/m³) were investigated. The microscopic analysis confirmed the presence of crystals of this in the cell lumina of wood tissue. Sorption properties were determined using an instrument capable of dynamic vapour sorption (DVS) assessment. DVS analysis confirmed that the sorption properties of impregnated spruce wood are comparable to those of non-impregnated spruce wood. However, the higher hysteresis at higher relative humidity is probably due to the presence of crystals in the cell lumina. Sorpcijske lastnosti lesa imajo značilen vpliv na nekatere njegove lastnosti. V največji meri vplivajo na mehanske lastnosti in dovzetnost lesa na glivni razkroj. Vlažnejši les je bolj dovzeten za glivni razkroj, zato ga pred glivnim razkrojem, fotodegradacijo ali gorenjem pogosto impregniramo. Predvsem anorganske soli vplivajo na sorpcijske lastnosti lesa. S tem namenom smo preiskali sorpcijske lastnosti smrekovine, impregnirane z ognjezadrževalnim sredstvom Burnblock (navzem 38 kg/m³). Mikroskopska analiza je potrdila prisotnost kristalov sredstva v celičnih lumnih lesnega tkiva. Sorpcijske lastnosti smo določili z opremo, ki vrednoti dinamično sorpcijo vodne pare (DVS). DVS analiza je potrdila, da so sorpcijske lastnosti impregniranega smrekovega lesa primerljive s sorpcijskimi lastnostmi neimpregnirane smrekovine. Večja histereza pri višjih relativnih zračnih vlažnostih je verjetno posledica prisotnosti kristalov anorganskih soli, ki so se izločili v celičnih lumnih po impregnaciji. Bibliografija: str. 21. Izvleček ; Abstract ; Povzetek.

The effects of thermal modification of wood have been well established, particularly in terms of reductions in mechanical performance. In recent years, there has been an increase in studies related to the Maillard reaction. More commonly associated with food chemistry, it involves the reaction of amines and reducing sugars during cooking procedures. This study has attempted to combine the use of amines and thermal modification, with subsequent properties investigated for the treatment of spruce (Picea abies (L.) H. Karst) and beech (Fagus sylvatica L.). In this initial study, the combined effects of chemical treatments by tricine and bicine were investigated with thermal modification. Along with some preliminary data on mechanical properties, the modifications which appeared in the wood structure were evaluated by infrared spectroscopy and biological studies according to EN113 and EN117 methodologies. The hierarchal study interpretation of FTIR suggested interactions between the bicine or tricine and the wood, which was partly supported by the analysis of volatile organic compounds (VOC), though other tests were not as conclusive. The potential of the method warrants further consideration, which will be described. Validerad;2022;Nivå 2;2022-05-30 (hanlid);Funder: COST Action FP1407;Part of special issue: Performance and Modification of Wood and Wood-Based Materials

Service life planning with timber requires reliable models for quantifying the effects of exposure-related parameters and the material-inherent resistance of wood against biotic agents. The Meyer-Veltrup model was the first attempt to account for inherent protective properties and the wetting ability of wood to quantify resistance of wood in a quantitative manner. Based on test data on brown, white, and soft rot as well as moisture dynamics, the decay rates of different untreated wood species were predicted relative to the reference species of Norway spruce (Picea abies). The present study aimed to validate and optimize the resistance model for a wider range of wood species including very durable species, thermally and chemically modified wood, and preservative treated wood. The general model structure was shown to also be suitable for highly durable materials, but previously defined maximum thresholds had to be adjusted (i.e., maximum values of factors accounting for wetting ability and inherent protective properties) to 18 instead of 5 compared to Norway spruce. As expected, both the enlarged span in durability and the use of numerous and partly very divergent data sources (i.e., test methods, test locations, and types of data presentation) led to a decrease in the predictive power of the model compared to the original. In addition to the need to enlarge the database quantity and improve its quality, in particular for treated wood, it might be advantageous to use separate models for untreated and treated wood as long as the effect of additional impact variables (e.g., treatment quality) can be accounted for. Nevertheless, the adapted Meyer-Veltrup model will serve as an instrument to quantify material resistance for a wide range of wood-based materials as an input for comprehensive service life prediction software.

Durability-based designs with timber require reliable information about the wood properties and how they affect its performance under variable exposure conditions. This study aimed at utilizing a material resistance model (Part 2 of this publication) based on a dose–response approach for predicting the relative decay rates in above-ground situations. Laboratory and field test data were, for the first time, surveyed globally and used to determine material-specific resistance dose values, which were correlated to decay rates. In addition, laboratory indicators were used to adapt the material resistance model to in-ground exposure. The relationship between decay rates in- and above-ground, the predictive power of laboratory indicators to predict such decay rates, and a method for implementing both in a service life prediction tool, were established based on 195 hardwoods, 29 softwoods, 19 modified timbers, and 41 preservative-treated timbers.

Wood is one of the most important construction materials, and its use in building applications has increased in recent decades. In order to enable even more extensive and reliable use of wood, we need to understand the factors affecting woodʹs service life. A new concept for characterizing the durability of wood-based materials and for predicting the service life of wood has recently been proposed, based on material-inherent protective properties, moisture performance, and the climate- and design-induced exposure dose of wooden structures. This approach was validated on the decking of a model house in Ljubljana that was constructed in October 2013. The decay and moisture content of decking elements were regularly monitored. In addition, the resistance dose D$_{Rd}$, as the product of the critical dose D$_{crit}$, and two factors taking into account the wetting ability of wood (k$_{wa}$) and its inherent durability (k$_{inh}$), were determined in the laboratory. D$_{Rd}$ correlated well with the decay rates of the decking of the model house. Furthermore, the positive effect of thermal modification and water-repellent treatments on the outdoor performance of the examined materials was evident, as well as the synergistic effects between moisture performance and inherent durability.

Les na prostem je izpostavljen delovanju abiotskih in biotskih dejavnikov. Če hočemo njihovo delovanje upočasniti, moramo les zaščititi. V preteklosti je bil biocidni proizvod na osnovi bakrovih, kromovih in borovih spojin (CCB) ena najpomembnejših rešitev za zaščito lesa v ostrih pogojih izpostavitve. Kljub temu, da se CCB v EU praktično ne uporablja več, lahko služi kot referenca za vrednotenje novih biocidnih proizvodov. Na terenskem polju Oddelka za lesarstvo Biotehniške fakultete že 14 let poteka poskus v realnih pogojih, kjer so impregnirani vzorci izpostavljeni vremenskim vplivom v skladu z dvoslojnim testom. Pri zaščitenem lesu pogosto opažamo, da les propade hitreje kot je pričakovano. V okviru tega prispevka želimo na podlagi analize razkrojenega s CCB impregniranega lesa s terenskega polja Oddelka za lesarstvo ugotoviti, zakaj je prišlo do prezgodnjega razkroja. Rezultati kažejo, da ustrezno življenjsko dobo zagotavljata ustrezna retencija in penetracija aktivnih učinkovin v les. Wood in outdoor applications is exposed to abiotic and biotic factors. If we want to slow down the decay, the wood must be protected. In the past, biocidal products based on copper, chromium, and boron compounds (CCB) were one of the most important solutions for wood protection under extreme conditions. Although CCB is in practice no longer used in the EU, it can serve as a reference for the evaluation of new biocidal products. At the field test site of the Department of Wood Science and Technology, Biotechnical Faculty, an experiment has been carried out under real conditions for 14 years, in which impregnated samples are exposed to the weather according to a double-layer test. In the case of treated wood, we often find that the wood decays faster than expected. In this work we want to determine what contributes to decay based on the analysis of decayed impregnated wood from the field test site. The results show that sufficient retention and penetration of the active substances into the wood ensures the planned service life.

Durability-based designs with timber require reliable information about the wood properties and how they affect its performance under variable exposure conditions. This study aimed at utilizing a material resistance model (Part 2 of this publication) based on a dose–response approach for predicting the relative decay rates in above-ground situations. Laboratory and field test data were, for the first time, surveyed globally and used to determine material-specific resistance dose values, which were correlated to decay rates. In addition, laboratory indicators were used to adapt the material resistance model to in-ground exposure. The relationship between decay rates in-and above-ground, the predictive power of laboratory indicators to predict such decay rates, and a method for implementing both in a service life prediction tool, were established based on 195 hardwoods, 29 softwoods, 19 modified timbers, and 41 preservative-treated timbers.

Pred drugo svetovno vojno so v okolici Golega vrha postavili obsežno podzemno utrdbo. Še od časa izgradnje je v utrdbi ostalo nekaj lesa, dodatno so pred leti namestili nekaj lesenih razstavnih predmetov. Na lesu je bilo nekaj let po odprtju opaziti obsežen glivni razkroj. V utrdbi smo namestili senzor za spremljanje relativne zračne vlažnosti in temperature, izolirali nekaj vzorcev lesa in jih preiskali z rentgensko fluorescenčno spektroskopijo in lasersko konfokalno vrstično mikroskopijo. Analiza je potrdila visoko vlažnost lesa in prisotnost gliv razkrojevalk na vseh lesenih eksponatih z izjemo lesenih zabojnikov za strelivo. Before the Second World War, a large underground fortress was built around Goli vrh. Some wood remains in the fort from the time of construction, and some wooden objects have been exhibited in the fort. Several years after the opening of the fort, large scale decomposition was observed on the wood. A sensor for monitoring the relative air humidity and temperature was installed. In addition, a few samples of wood were isolated and examined by X-ray fluorescence spectroscopy and laser confocal linear microscopy. The analysis confirmed the high humidity of the wood and the presence of wood decay fungi on all wood objects, with the exception of wooden ammunition boxes.

Simple Summary Over the past thirty years, the thermal modification of wood has become a universally recognised and commercialised wood modification process. Thermal modifications may affect wood properties, either positively (dimensional stability and decay resistance) or negatively (mechanical properties). The combination of the impregnation of specific reagents with thermal modification may help to overcome the negative effects on wood properties. In this study, we evaluate the effect of a combination of two zwitterionic buffers, bicine and tricine, and thermal modification of two wood species (beech and spruce) against subterranean termites and their symbiotic fauna. Bicine and tricine treatments alone had a clear influence on wood mass loss and termite survival. The flagellate protist symbiotic community was affected by the treatments and responded differently to them, as a highly adaptable community. However, the combination of bicine with the thermal modification showed a negative effect on termites and their symbionts on both wood species. The combination of these different factors should be further investigated, as these results seem to be promising with regard to the enhancement of the termite resistance of wood. Abstract The majority of thermal modification processes are at temperatures greater than 180 °C, resulting in a product with some properties enhanced and some diminished (e.g., mechanical properties). However, the durability of thermally modified wood to termite attack is recognised as low. Recent attempts at combining thermal modification with chemical modification, either prior to or directly after the thermal process, are promising. Buffers, although not influencing the reaction systems, may interact on exposure to certain conditions, potentially acting as promoters of biological changes. In this study, two zwitterionic buffers, bicine and tricine, chosen for their potential to form Maillard-type products with fragmented hemicelluloses/volatiles, were assessed with and without thermal modification for two wood species (spruce and beech), with subsequent evaluation of their effect against subterranean termites (Reticulitermes grassei Clément) and their symbiotic protists. The effect of the wood treatments on termites and their symbionts was visible after four weeks, especially for spruce treated with tricine and bicine and heat treatment (bicine HT), and for beech treated with bicine and bicine and heat treatment (bicine HT). The chemical behaviour of these substances should be further investigated when in contact with wood and also after heat treatment. This is the first study evaluating the effect of potential Maillard reactions with zwitterionic buffers on subterranean termite symbiotic fauna.

Predstavljamo raziskavo arheološkega lesa iz koliščarske naselbine Dušanovo na Ljubljanskem barju. Med zaščitnim izkopavanjem v letu 2013 so arheologi odvzeli vzorce 210 pilotov. Preiskali smo jih po uveljavljeni metodi, ki vključuje obdelavo, makroskopsko ali mikroskopsko identifikacijo lesa, merjenje in dendrokronološke raziskave. Prevladoval je les jesena (Fraxinus sp.), ki je predstavljal 78 % lesa, sledil je les topola (Populus sp.) s 7 %, javorja (Acer sp) s 4 %, jelše (Alnus glutinosa) s 3 % ter belega gabra (Carpinus betulus), vrbe (Salix sp.), hrasta (Quercus sp.) in bresta (Ulmus sp.), ki so predstavljali vsak po 2 % lesa. Izbor lesnih vrst nakazuje, da so les večinoma sekali na poplavnih terenih v bližini naselbine. 64 vzorcev jesenovih kolov je imelo 45 ali več branik in so bili po uveljavljenih kriterijih primerni za dendrokronološko analizo. Zaporedja širin branik 15 vzorcev smo sinhronizirali, združili v kronologijo DU-FRSP1 in jo datirali s kronologijo kolišča Črni graben v leto 2491 (% 18) kal. pr. n. št. Izkazalo se je, da je kolišče Dušanovo živelo ob zaključku bakrene dobe, hkrati z naselbinami Črni graben, Založnica in Parte. Isto obdobje poseka lesa nakazuje, da sta bili naselbini Dušanovo in bližnji Črni graben morda celo del iste naselbine. Premeri kolov so znašali med 5 in 18 cm, nad 80 % jih je imelo premer od 7 do 12,5 cm. Slaba polovica (40 %) kolov je imela branike široke 1-2 mm. Koli so imeli od 11 do 156 branik, skoraj polovica je imela manj kot 30 branik, kar nakazuje približno starost dreves ob poseku. Najmlajša so bila drevesa vrbe, sledijo jelša, topol, hrast, javor, brest in beli gaber. Največ branik je v splošnem imel jesen, kar je najverjetneje posledica polardiranja - sekanja vej za prehrano živali. Sledove polardiranja, ki se odraža v manjšem prirastku in spremenjeni zgradbi lesa, smo zasledili in natančneje proučili na vzorcih lesa 10 jesenov. We present investigations of archaeological wood from the pile-dwelling site of Dušanovo on Ljubljansko barje (the Ljubljana Marshes). During rescue excavations in 2013, archaeologists took samples from 210 piles. We investigated the waterlogged archaeological wood using an established method which involves wood processing, macroscopic or microscopic wood identification, measuring, and dendrochronological research. Ash wood (Fraxinus sp.) was dominant, representing 78% of the collected archaeological wood, followed by poplar (Populus sp.) with 7%, maple (Acer sp.) with 4%, alder (Alnus glutinosa) with 3%, and hornbeam (Carpinus betulus), willow (Salix sp.), oak (Quercus sp.), and elm (Ulmus sp.), each representing 2%. The selection of wood species suggests that most of the wood was felled in a flood-prone terrain in the vicinity of the settlement. 64 samples of ash piles had 45 or more tree rings and were, by established criteria, suitable for dendrochronological analysis. Tree-ring series of 15 samples were cross-dated, integrated into the chronology of DU-FRSP1 and dated with the chronology of the pile dwelling of Črni Graben to the year 2491 (% 18) cal. BC. The results indicate that Dušanovo was inhabited at the end of the Copper Age, at the same time as the settlements of Črni graben, Založnica and Parte. The same period of tree felling indicates that the settlements of Dušanovo and the nearby Črni Graben might have been a part of the same settlement. The piles were between 5 and 18 cm in diameter, with more than 80% of them between 7 and 12.5 cm in diameter. Less than a half (40%) of the piles had tree-ring widths of 1-2 mm. The piles had between 11 and 156 tree rings, and nearly a half of them had fewer than 30 tree rings, indicating the approximate age of the trees at the time of felling. Willow trees were the youngest, followed by alder, poplar, oak, maple, elm and hornbeam. In general, ash had the most tree rings, most likely due to pruning (cutting branches for animal consumption). We have observed and studied the traces of pruning that are reflected in a smaller increment and a modified structure of wood in 10 samples of ash.