11. Quality control of thermally modified timber using dynamic vapor sorption (DVS) analysisMiha Humar, Rožle Repič, Davor Kržišnik, Boštjan Lesar, Romana Cerc Korošec, Christian Brischke, Lukas Emmerich, Gregor Rep, 2020, original scientific article Abstract: The importance of thermal modification is increasing worldwide. Increased use of thermally modified timber (TMT) has resulted in a need for reliable quality control, comprising control of variation of the production within defined limits, allowing third-party control in the case of certification and the regulation of customer complaints and claims. Techniques are thus needed to characterise the modification of quality in terms of improved target properties of TMT during industrial production, and of TMT products that have been in service for an arbitrary time. In this study, we aimed to utilise dynamic vapor sorption (DVS) for this purpose. Norway spruce (Picea abies) and European beech (Fagus sylvatica) samples were thermally modified at different temperatures according to different heat treatment techniques: (1) the Silvapro process based on an initial vacuum; (2) an air heat treatment, whereby samples were wrapped in aluminium foil; (3) thermal modification of wood samples in the ambient atmosphere in a laboratory oven. Wood samples from closed processes were analysed for validation. TMT was characterised with respect to mass loss, colour and density. Mass loss of wood due to modification (MLTM) was correlated with factors derived from DVS analysis. The present DVS measurements suggest that the equilibrium wood moisture content (EMC95% RH), the time to reach 10% wood moisture content (t10% MC), and the elongation factor, c, derived from a logarithmic function, can serve as alternative parameters to characterise the quality of several thermal modification processes. Further studies are recommended using other wood species, different modification processes and further parameters gained from DVS measurements to understand the robustness and the predictive power of the applied technique Keywords: thermal modification, quality control, dynamic vapour sorption, wood, moisture content Published in DiRROS: 31.08.2023; Views: 520; Downloads: 248
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12. Methodology for evaluating the CO2 sequestration capacity of waste ashesSara Tominc, Vilma Ducman, 2023, original scientific article Abstract: The concentration of CO2 in the atmosphere is constantly increasing, leading to an increase in the average global temperature and, thus, affecting climate change. Hence, various initiatives have been proposed to mitigate this process, among which CO2 sequestration is a technically simple and efficient approach. The spontaneous carbonation of ashes with atmospheric CO2 is very slow, and this is why accelerated carbonation is encouraged. However, not all ashes are equally suitable for this process, so a methodology to evaluate their potential should be developed. Such a methodology involves a combination of techniques, from theoretical calculations to XRF, XRD, DTA-TG, and the calcimetric determination of the CaCO3 content. The present study followed the approach of exposing ashes to accelerated carbonation conditions (4% v/v CO2, 50–55% and 80–85% RH, 20 ◦C) in a closed carbonation chamber for different periods of time until the maximum CO2 uptake is reached. The amount of sequestered CO2 was quantified by thermogravimetry. The results show that the highest CO2 sequestration capacity (33.8%) and carbonation efficiency (67.9%) were obtained for wood biomass bottom ash. This method was applied to eight combustion ashes and could serve to evaluate other ashes or comparable carbon storage materials. Keywords: CO2 sequestration, carbonation efficiency, coal ash, wood biomass ash, co-combustion ash, DTA-TG analysis Published in DiRROS: 08.08.2023; Views: 569; Downloads: 269
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13. Makroekonomski učinki proizvodnje in predelave lesa listavcevDomen Arnič, Peter Prislan, Luka Juvančič, 2023, original scientific article Abstract: As far as the utilization of the value-added potential of hardwood assortments is concerned, we have considerable reserves in Slovenia. These could be exploited mainly by increasing the economic use of roundwood in Slovenia and by developing more technologically advanced processing methods for roundwood. The aim of this paper is to assess the untapped potential of the forest-wood chain in Slovenia using input-output models, focusing on the use of hardwood. For the whole forest-wood chain, we assessed the existing situation and tested five scenarios for the improvement of the forest-wood chain in Slovenia. We developed a national input-output model to evaluate possible scenarios for the future development of the wood-based bioeconomy. The results of scenario analysis of the input-output model show that the Slovenian wood-based bioeconomy can achieve up to 20% higher production value, a 24% increase in employment and 19% increase in household income in the future through restructuring of economic activities. In the paper, we discuss how upgrading the forestry and wood-processing industry (according to the defined scenarios) could be achieved by increasing the processing capacity of hardwoods and provide recommendations for decision makers. Keywords: forest- and wood-based bioeconomy, hardwoods utilization, input-output models, wood processing industry, scenario analysis, mobilization of hardwoods Published in DiRROS: 03.08.2023; Views: 531; Downloads: 288
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14. Improving the flame retardancy of wood using an eco-friendly mineralisation processAndreja Pondelak, Andrijana Sever Škapin, Nataša Knez, Friderik Knez, Tomaž Pazlar, 2021, original scientific article Abstract: A novel environmentally friendly method for in situ formation of CaCO3 deep inside a wood’s structure is presented. The method is based on vacuum-pressure impregnation using a one-component treatment medium – a water solution of calcium acetoacetate - and a single stage process to significantly improve the fire retardancy of the treated material. Keywords: mineralisation, flame retardancy, calcium acetoacetate, calcium carbonate, wood Published in DiRROS: 31.07.2023; Views: 572; Downloads: 393
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15. Effects of selected printing parameters on the fire properties of 3D-printed neat polylactic acid (PLA) and wood/PLA compositesNataša Knez, Mirko Kariž, Friderik Knez, Nadir Ayrilmis, Manja Kitek Kuzman, 2021, original scientific article Abstract: The effects of selected printing parameters on the fire properties of additively produced composites from neat polylactic acid (PLA) and wood/PLA filaments were investigated. The reaction to fire of the 3D-printed specimens was tested according to the ISO 5660-1 cone calorimeter test method. The results showed that the properties of the specimens when exposed to fire were significantly affected by the incorporation of wood flour into the PLA filament. It was also interesting that PLA specimens had much better reactions to fire than the wood/PLA specimens. Time to ignition was found to be much longer in the 3D-printed PLA specimens. Although the maximal heat release rate was a little higher in the PLA than the wood/PLA specimens, the duration of HRR was longer for the wood/PLA specimens. The initial mass of the specimens was smaller in the wood/PLA composites, but during the radiant heat exposure the mass typically decreased slower than in the PLA specimens. Keywords: reaction to fire, wood, polylactic acid (PLA), filament, 3D printer, biocomposite Published in DiRROS: 17.07.2023; Views: 452; Downloads: 287
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16. Dataset for the article Methodology for evaluating the CO2 sequestration capacity of waste ashesVilma Ducman, Sara Tominc, 2023, complete scientific database of research data Abstract: The dataset supports the data in the tables and figures in the article Methodology for evaluating the CO2 sequestration capacity of waste ashes (doi: 10.3390/ma16155284). It contains the original masses of waste ash before and during carbonation treatment, the sequestered CO2 masses after carbonation treatment, mass uptake calculations, calcimetric measurements, calculations of theoretical maximum sequestered CO2 (based on XRF results) and carbonation efficiency (CE), original results of DTA/TG analysis of individual ashes, original results of XRF measurement and data from XRD analyses supported by X-ray diffractograms not published in the article. Keywords: CO2 sequestration, carbonation efficiency, coal ash, wood biomass ash, co-combustion ash, DTA-TG analysis Published in DiRROS: 14.07.2023; Views: 890; Downloads: 371
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17. Use of the modified controlled atmosphere cone calorimeter for the assessment of fire effluents generated by burning wood under different ventilation conditionsFriderik Knez, Matija Uršič, Nataša Knez, Kelly Peeters, Mladen Franko, Primož Zidar, 2021, original scientific article Abstract: The ISO 5660-1 cone calorimeter is an affordable, practical, and commonly used solution for the measurement of main fire properties of products and materials. Among its chief drawbacks is its limited ability to reproduce combustion conditions found in real fires. This deficiency is mainly due to its inability to control oxygen availability in order to simulate an underventilated fire. As several toxic or potentially toxic species are formed primarily in oxygen-poor conditions, the controlled atmosphere cone calorimeter (CACC), now defined in ISO 5660-5, is a major improvement when trying to study the toxicity of fire effluents. A proposed additional modification of the CACC via the introduction of chimney sampling ports and oxygen sensors improves the reproducibility and veracity of effluent sampling. This approach allows the implementation of various techniques to sample, collect, and analyze the generated fire effluents. In this study, the experimental set-up was used to capture fire effluents generated by burning wood under different ventilation conditions. A gas chromatograph coupled with mass spectrometer was used to assess and compare the chemical composition of the collected samples. The results obtained with the new experimental set-up proved the ability of the system to reproducibly generate fire effluents under various controlled burning circumstances. It could prove useful as a tool in characterizing the toxicity of fire effluents from various materials on a benchtop scale and ultimately contribute data for the numerical modeling of toxicity of fire effluents in real buildings. Keywords: modified cone calorimeter, controlled atmosphere, wood, fire effluents, open access Published in DiRROS: 14.07.2023; Views: 612; Downloads: 429
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18. Environmentally friendly protection of European beech against fire and fungal decay using a combination of thermal modification and mineralisationRožle Repič, Andreja Pondelak, Davor Kržišnik, Miha Humar, Nataša Knez, Friderik Knez, Andrijana Sever Škapin, 2024, original scientific article Abstract: 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. Keywords: wood, protection, durability, mechanical properties Published in DiRROS: 12.07.2023; Views: 535; Downloads: 390
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19. Combining mineralisation and thermal modification to improve the fungal durability of selected wood speciesRožle Repič, Andreja Pondelak, Davor Kržišnik, Miha Humar, Andrijana Sever Škapin, 2022, original scientific article Abstract: The development of non-biocidal and environmentally friendly systems to protect wood against biological decay has become a high priority in recent years. In the present study the impact of an innovative modification procedure, combining two environmentally friendly modification methods: thermal modification and mineralisation, using an aqueous solution of calcium acetoacetate as a precursor, on the fungal durability of wood was evaluated. European beechwood (Fagus sylvatica) and Norway sprucewood (Picea abies) were selected as model wood species. Wood samples were treated using either a single or combination of both methods and exposed to four different fungi: Gloeophyllum trabeum, Rhodonia placenta, Trametes versicolor and Pleurotus ostreatus. The effect of the different modifications on moisture content, dynamic vapour sorption, contact angle and pH value was also evaluated. Overall, the highest durability against Rhodonia placenta, Trametes versicolor and Pleurotus ostreatus was achieved through thermal modification in both wood species, while the combination of mineralisation and thermal modification has a synergistic effect against degradation by Gloeophyllum trabeum. In the case of beechwood the mass loss decreased from 41% for native to 6% for combined modified samples. We proved that the effectiveness of different treatment against fungal decay of wood were in strong dependence of their moisture content, dynamic vapour sorption, contact angle and pH values. The role of fungi on the morphology of the wood and on crystal structure of formed carbonate was investigated using SEM-EDS analysis. Keywords: thermal modification, wood mineralization, fungal durability, environmentally friendly modification methods Published in DiRROS: 20.06.2023; Views: 545; Downloads: 540
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20. Flood vulnerability study of a roadway bridge subjected to hydrodynamic actions, local scour and wood debris accumulationMirko Kosič, Andrej Anžlin, Valentina Bau', 2022, original scientific article Abstract: The increased occurrence and intensity of flooding events have represented a real threat to bridge reliability and end-user safety. As flood vulnerability assessment is a valuable tool for enhancing the resilience of bridges to climate change, it is of interest to push the development of such methods. To this end, a computationally efficient methodology to assess the flood vulnerability of a bridge was developed and implemented in a case study. A particular focus was devoted to modelling wood debris loads on the bridge pier, for which two different approaches were implemented. The first is a standards-based approach, whereas the second is based on up-to-date research data. The results indicate that the second approach is less conservative as it leads up to a 40% higher exceedance probability for the considered limit states. The interaction between wood debris loads and local scour was also examined and proved to have a relevant impact on the vulnerability of the bridge. These results highlight the shortcomings of the existing standards in providing accurate results. It is perceived that not only will the new quantitative tool be valuable in ensuring optimal bridge design, but it will also be beneficial for assessing bridge risk mitigation measures. Keywords: flooding, vulnerability, wood debris, local scour, hydrodynamic load, stochastic approach, bridges, open access Published in DiRROS: 31.05.2023; Views: 568; Downloads: 308
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