1. Enhancing the fire resistance and fungal durability of solid wood via magnesium carbonate-based mineralization methodNataša Knez, Srečo D. Škapin, Miha Humar, 2026, izvirni znanstveni članek Povzetek: Enhanced fire performance and durability of wood materials and products without harmful chemicals remains an important challenge. We propose a specific magnesium carbonate-based mineralization method for improving wood durability and fire resistance. During mineralization wood samples were impregnated with an aqueous solution of magnesium acetoacetate, which subsequently transforms within the wood to form various magnesium carbonate-based compounds, predominantly different hydrated and basic phases, the specific formation of which is influenced by factors such as wood anatomy and environmental conditions during post-treatment. Unlike traditional calcium carbonate, magnesium carbonates decompose at much lower temperatures, releasing both water and CO₂, which together contribute to enhanced flame protection through cooling and dilution of flammable gases. This treatment delayed ignition time by over 50% in two case studies, Norway spruce and European beech, compared to untreated controls. Additionally, such mineral-wood composites showed significantly lower mass loss when exposed to fungi, attributed to increased alkalinity compared to the untreated wood’s acidity. This dual-function mineralization approach offers an environmentally friendly alternative for improving fire and decay resistance and presents a non-hazardous biocide-free method that could replace certain conventional treatments.
Ključne besede: mineralization, MgCO3, reaction to fire, fungal durability, environmentally friendly
Objavljeno v DiRROS: 18.05.2026; Ogledov: 333; Prenosov: 426
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2. In-situ hydroxyapatite mineralization in beech and pine wood : effects of leaching on fire behaviorMatic Sitar, Sabina Dolenec, Nataša Knez, Miha Hren, Boštjan Lesar, 2026, izvirni znanstveni članek Povzetek: This study presents the in-situ synthesis of hydroxyapatite (HAp) within the structure of beech and pine wood. The modification process utilized a two-step vacuum-pressure impregnation coupled with chemical precipitation using calcium nitrate tetrahydrate and diammonium hydrogen phosphate solutions, followed by exposure to ammonium hydroxide vapors. While the initial focus was on the overall physicochemical changes, microstructural characteristics and fire behavior of the mineralized wood, the main aim is to specifically investigate the effects of leaching. Because HAp synthesis produces water-soluble ammonium nitrate (NH4NO3) as a by-product, this research systematically addresses how the removal of this component affects the final properties of wood. HAp formation was confirmed by FTIR and X-ray diffraction, while scanning electron microscopy and microcomputed tomography revealed HAp deposits primarily in the cell lumen of both wood species. Fire behavior was evaluated using thermal analysis and the cone calorimeter. The incorporation of non-flammable HAp synthesized within the wood structure may act as a barrier and mass transfer during pyrolysis. This results to comparable or slightly enhanced key fire performance parameters when comparing leached HAp synthesized samples with leached reference samples. In contrast, the unleached HAp synthesized samples, which still contained residual NH4NO3, showed deterioration in fire growth rate (FIGRA) and heat release rate (HRR) parameters, confirming that NH4NO3 acts as an oxidant. However, this oxidative property also leads to improvements in total heat release (THR) and total smoke production (TSP) parameters compared to unleached references, representing a complex interaction when studying the fire properties of mineralized wood.
Ključne besede: chemical precipitation method, fire retardancy, hydroxyapatite, HAp, leaching process, wood
Objavljeno v DiRROS: 17.04.2026; Ogledov: 456; Prenosov: 458
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3. Enhancing wood sample preparation for SEM imaging : a detailed study of epoxy resin impregnation, cutting, sanding, and polishing for fragile and heterogeneous samplesRožle Repič, Maks Merela, Andreja Pondelak, Andrijana Sever Škapin, 2026, izvirni znanstveni članek Povzetek: Accurate characterization of wood microstructure requires high-quality sample preparation, especially for degraded, mineralized, or embedded samples. Through a detailed and systematic investigation, we suggest a simple, fast, and cost-effective method for preparing transverse surfaces of wood for scanning electron microscopy. The methodology used is easily accessible and simple. We compare traditional microtome cutting using both disposable blades and a fixed knife with sanding and polishing techniques. The choice of method is determined by the physical condition and structural characteristics of the sample. Disposable blades, when used with continuous moistening, yielded the best results for reference wood, while the fixed knife proved to be more effective for mineralized or epoxy-embedded samples due to their rigidity and resistance to deflection. Maintaining blade sharpness and surface moisture were critical in all cutting techniques. Polishing proved to be a particularly effective technique for the preparation of degraded, mineral-rich, or heterogeneous samples. In combination with epoxy embedding, it offers a practical alternative to microtome cutting, ensuring the protection of fragile structures, the long-term stability of samples, and the possibility of re-polishing. Epoxy impregnation was easy for degraded wood, while sprucewood required vacuum-pressure treatment. Care must be taken when polishing to avoid reaching non-embedded regions beneath the surface.
Ključne besede: epoxy resin impregnation, polishing and sanding, sample preparation, scanning electron microscopy, wood
Objavljeno v DiRROS: 27.01.2026; Ogledov: 1061; Prenosov: 569
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4. Non-invasive techniques in consolidation study of dolomitic lime plasters : application to wall paintingsZala Žarkovič, Andreja Pondelak, Ajda Mladenovič, Sabina Dolenec, 2025, objavljeni znanstveni prispevek na konferenci Povzetek: The consolidation of lime-based plaster materials plays a vital role in preservation of built heritage. Wall paintings are particularly vulnerable due to the fragile nature of lime-based substrates and their susceptibility to deterioration. While calcium lime plasters are frequently studied, there seem to be few studies on the consolidation of wall paintings produced with dolomitic lime. This research evaluates the effectiveness of three carbonate-based consolidants — calcium acetoacetate (CFW), Nanorestore (NR), and NanoLaq (NL) applied individually and in combinations, to assess their mechanical and aesthetic effects on dolomitic lime models. Non-invasive methods included microhardness testing, ultrasonic velocity measurements and micro-invasive method as the drilling resistance measurement system (DRMS) to measure penetration depth and change in mechanical properties. Spectrophotometry was used to monitor colour changes after the application of consolidants. This research emphasizes the significance of using advanced diagnostic tools for evaluating and improving conservation treatments for wall paintings. Results showed that combined applications of CFW with nanolimes improved cohesion and depth performance significantly more than individual treatments. The findings contribute to sustainable practices in heritage preservation and align with ongoing efforts to refine consolidant formulations for better performance.
Ključne besede: non-destructive testing, infrared thermography, historic concrete preservation, ground penetrating radar (GPR), ultrasound tomography
Objavljeno v DiRROS: 15.01.2026; Ogledov: 712; Prenosov: 390
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5. Dynamic mechanical analysis of fpu bonded beech wood at various temperaturesMartin Capuder, Boris Azinović, Andreja Pondelak, Paweł Rutkowski, Magdalena Szumera, Matthew Schwarzkopf, Arkadiusz Kwiecień, Klaudia Śliwa-Wieczorek, Jaka Gašper Pečnik, 2025, objavljeni znanstveni prispevek na konferenci Povzetek: This study investigates the dynamic mechanical properties of flexible polyurethane (FPU) adhesives bonded to European beech wood (Fagus sylvatica L.) using Dynamic Mechanical Analysis (DMA) over a range of temperatures and frequencies. Samples included clear beech wood and three-layered composite (beech:FPU:beech). DMA tests were performed using a three-point bending setup at 1 Hz and 10 Hz in the temperature range from -120°C to 140°C. The results demonstrated high thermal stability and strong bonding performance of FPU adhesives on beech wood. Frequency-dependent responses varied among FPU types but resembled the behavior of solid wood at lower temperatures. This confirms the suitability of DMA for evaluating adhesive-wood composite behavior under dynamic conditions. The combination of FPU adhesives and beech wood showed potential for thermally stable and energy-dissipating bonded assemblies.
Ključne besede: dynamic mechanical analysis, FPU, beech wood
Objavljeno v DiRROS: 27.08.2025; Ogledov: 862; Prenosov: 481
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6. Natural exposure comparison of timber joints bonded with polyurethane adhesive in two climatic conditionsMartin Capuder, Gary M. Raftery, Weixi Wang, Zubin Karami, Boris Azinović, Andreja Pondelak, Luka Naumovski, Tomaž Pazlar, 2025, objavljeni znanstveni prispevek na konferenci Povzetek: The increased use of engineered wood in the built environment is attracting much attention because of the significant sustainable attributes. The formation of high quality reliable structural adhesive bonds is essential during the manufacture of such products. This research examines and compares the performance of bonded European beech and Radiata pine subject to natural weathering, comparing untreated, preservative treated and mineralized wood. Bonded joints were naturally weathered in Slovenia and New Zealand, respectively. The fracture energy was evaluated through Mode I fracture tests using the double cantilever beam arrangement at various ageing stages. FTIR analysis was conducted to assess chemical changes in the adhesives and wood substrate. The research provides insights into the interactions between ageing, wood species, and adhesive performance, enhancing timber structures sustainability.
Ključne besede: durability, weathering, climate, adhesive bond, mode I fracture testing
Objavljeno v DiRROS: 27.08.2025; Ogledov: 913; Prenosov: 513
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7. Mehanske lastnosti lepljenih spojev : vpliv izpostavljenosti in naravnega staranjaMartin Capuder, Boris Azinović, Andreja Pondelak, Tomaž Pazlar, Jaka Gašper Pečnik, Luka Naumovski, 2025, objavljeni povzetek znanstvenega prispevka na konferenci Ključne besede: bukev, lepljen spoj, FTIR, naravna izpostavitev, mehanske lastnosti lesa
Objavljeno v DiRROS: 05.06.2025; Ogledov: 1107; Prenosov: 456
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8. Dataset for the article Enhancing the fire resistance and fungal durability of solid wood via magnesium carbonate-based mineralization methodAndreja Pondelak, Nataša Knez, Srečo D. Škapin, Miha Humar, Andrijana Sever Škapin, 2025, raziskovalni podatki Povzetek: The dataset supports the data in the tables and figures in the scientific article Enhancing the fire resistance and fungal durability of solid wood via magnesium carbonate-based mineralization method (doi: https://doi.org/10.1016/j.conbuildmat.2026.146355). It contains original data of thermo-gravimetric analysis (TGA) and differential thermal analysis (DTA) coupled with a mass spectrometer (MS), equilibrium moisture content (EMC), pH values, cone calorimetry data and fungal durability test according to EN 113-1 (2021).
Ključne besede: mineralization, MgCO3, reaction to fire, fungal durability, environmentally friendly
Objavljeno v DiRROS: 15.05.2025; Ogledov: 372; Prenosov: 134
 Raziskovalni podatki (189,06 KB) |
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10. Stabilization of fish protein‐based adhesive by reduction of its hygroscopicityBranka Mušič, Jaka Gašper Pečnik, Andreja Pondelak, 2024, izvirni znanstveni članek Povzetek: Protein-based fish adhesives have historically been used in various bonding applications; however, due to the protein’s high affinity for water absorption, these adhesives become destabilized in high-moisture environments, resulting in reduced bondline strength and early failure. This limitation makes them unsuitable for industrial applications with higher demands. To address this issue, water-insoluble raw powder materials such as iron, copper, or zeolite were incorporated into natural fish adhesives. In this study, the hygroscopicity, dry matter content, thermal analysis (TGA/DSC), FT-IR spectroscopy, surface tension measurements, vapour permeability, and scanning electron microscope (SEM) of the modified adhesives were determined. In addition, the bonding properties of the modified adhesives were evaluated by the tensile shear strength of the lap joints, and mould growth was visually inspected. The resulting modified protein-based adhesives demonstrated improved stability in high humidity environments. Enhancing the hygroscopic properties of protein-based fish adhesives has the potential to unlock new opportunities and applications, providing a healthier and more environmentally sustainable alternative to petroleum-based adhesives.
Ključne besede: protein‐based adhesive, polymer stabilization, hygroscopicity, fish adhesive modification, fish industry waste, circular economy, bonding properties
Objavljeno v DiRROS: 12.08.2024; Ogledov: 1646; Prenosov: 1256
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