1. Pyrolysis oil-based polyurethane foams as a middle layer of the composite plywood sandwich panels for sustainable constructionJakub Grzybek, Jakub Michal Sandak, David Contus, Andrea Minigher, Hans Heeres, Bert van de Beld, Erfan Asgari, Rok Prislan, Anna Malgorzata Sandak, 2026, original scientific article Abstract: The construction sector’s substantial contribution to global energy consumption and CO2 emissions motivates the development of bio-based alternatives to fossil-derived rigid polyurethane (PUR) foam cores in structural sandwich panels. This study presents a comprehensive comparison of plywood sandwich panels manufactured with a rigid PUR foam containing a fast pyrolysis bio-oil (FPBO)-derived sugar polyol diluted with triethyl phosphate and panels of identical topology produced with a commercial reference PUR foam. In the bio-based formulation, a fraction of the sorbitol-based polyether polyol was replaced with the FPBO-derived sugar polyol. Both systems were characterized at the foam and panel levels for cellular microstructure, skeletal and envelope density, thermogravimetric stability, flammability, color, thermal conductivity and heat capacity, internal bond strength, compressive properties, and normal-incidence sound absorption and transmission loss. The newly developed foam exhibited similar skeletal density and porosity to the reference, comparable thermogravimetric stability with a slightly higher char residue, and lower thermal conductivity across the tested temperature range. Mechanical properties, including compressive strength, compressive modulus, and internal bond strength, showed minor reduction but remained within a comparable range. A distinct color change was observed, attributable to the presence of chromophoric constituents of the FPBO fraction. Overall, the results indicate that partial substitution of the fossil polyol with an FPBO-derived sugar polyol is technically feasible, yielding materials with comparable thermal, mechanical, or acoustic performance. No consistent performance advantage of either system was observed across the evaluated properties. The results support the potential of pyrolysis-derived bio-polyols for use in sustainable structural insulation products.
Keywords: bio-based polyol, fast pyrolysis bio-oil, rigid polyurethane foams, waste valorization
Published in RUP: 14.07.2026; Views: 217; Downloads: 6
 Full text (2,12 MB)
This document has more files! More... |
2. Wood modification using Fast Pyrolysis Bio-Oil (FPBO) : formulation development, characterization, and evaluation of wood performanceAnna Malgorzata Sandak, Faksawat Poohphajai, Amina Selmanović, Rene Alexander Herrera Diaz, Jakub Grzybek, Kelly Peeters, Sasikala Perumal, Edit Földvári-Nagy, Lei Han, Richard Acquah, Jakub Michal Sandak, 2026, original scientific article Abstract: This study presents a wood modification process using Fast Pyrolysis Bio-Oil (FPBO) as a fully biobased alternative to conventional, fossil-based and potentially toxic preservatives such as copper salts, organic biocides, and creosote. Standard FPBO was used in the devel- opment of 10 formulations, which were systematically characterized in terms of pot life, viscosity evolution, density, and pH. Radiata pine samples were subsequently impregnated using a bench-scale reactor, with specimens prepared in multiple geometries to assess treat- ment performance across different dimensions. The modified wood was comprehensively characterized with respect to moisture uptake, dimensional stability, density, mechanical strength, fixation efficiency, biological durability, and VOC emissions. Additional screening focused on properties relevant to outdoor applications, including aesthetic appearance and colour uniformity after UV exposure. The results enabled the identification of three top-performing formulations, treatments H, A, and E, which exhibited the most favourable balance between durability, environmental performance, and structural integrity. Overall, the findings demonstrate the strong potential of FPBO-based impregnation as a sustainable, multifunctional, and high-performance alternative for advanced wood protection systems.
Keywords: wood modification, fast pyrolysis bio-oil (FPBO), durability, bio-based impregnation treatment
Published in RUP: 29.06.2026; Views: 280; Downloads: 5
Full text (2,19 MB)
This document has more files! More... |
3. Moisture-dependent transition from strong to weak hydrogen bonding in wood polysaccharidesFilip Majstorović, Jakub Michal Sandak, 2026, original scientific article Abstract: Near-infrared (NIR) spectroscopy combined with multivariate analysis was employed to investigate moisture- dependent hydrogen bonding of water in softwood cell walls. Spectral variations at equilibrium moisture con- tents were analyzed using principal component analysis and perturbation-correlation moving-window two- dimensional correlation spectroscopy to distinguish water populations with varying hydrogen-bond strengths. A distinct transition in hydrogen-bonding behavior was identified at approximately 10% wood moisture content. Below this threshold, water was found to predominantly engage in strong hydrogen bonds within wood cell walls. Above 10% moisture content, the relative contribution of strong hydrogen bonds to the overall wood- water hydrogen bond network decreased, whereas weakly hydrogen-bonded population became increasingly dominant. Experiments on modified wood and isolated polymers indicated that this transition originates mainly from wood polysaccharides, while lignin plays a minor role. These findings provide strong evidence for distinct water populations in wood cell walls, distinguished by their intermolecular hydrogen-bonding energies and predominant at specific wood moisture contents
Keywords: infrared spectroscopy, wood-water interactions, hydrogen bonding, wood cell wall, cellulose
Published in RUP: 05.06.2026; Views: 369; Downloads: 11
Full text (4,60 MB)
This document has more files! More... |
4. Evaluation of the effectiveness of black tea leaves wastes as phytochemical-rich plant fillers and natural antioxidant in polyethyleneJoanna Aniśko-Michalak, Jakub Michal Sandak, Aleksander Hejna, Mateusz Barczewski, 2026, original scientific article Abstract: The aim of this study is to compare the structure as well as the mechanical and thermomechanical properties of polyethylene stabilized with a petrochemical additive (Irganox 1010) and a sustainable alternative, antioxidant-rich black tea waste leaves (BTW). The influence of both stabilizers was evaluated for samples produced by compression, injection, and rotational molding (CM, INM, and RM). The polymer ma- trix used was low-density polyethylene LDPE SBC 818 I’m Green® (Braskem), modified with 5 wt% BTW and an equiva- lent amount of Irganox 1010 based on the total phenolic con- tent in BTW. Stabilization efficiency was assessed using Fourier transform infrared spectroscopy (FTIR) and calori- metric techniques, including oxidation induction time (OIT) and oxidation onset temperature (OOT), both measured by differential scanning calorimetry (DSC). Additionally, porosity, mechanical performance in static tensile testing, and Vicat softening temperature (VST) were determined to provide a comprehensive comparison of the stabilization systems.
Keywords: polyethylene, thermoplastics, antioxidants, rotational molding, stabilization
Published in RUP: 02.06.2026; Views: 337; Downloads: 14
Full text (2,03 MB)
This document has more files! More... |
5. BIM-based wind-driven rain modelling using ISO 15927-3 and geometry-based exposureRichard Acquah, Jonas Niklewski, Jakub Michal Sandak, 2026, original scientific article Abstract: Wind-driven rain (WDR) is a key source of façade moisture risk. ISO 15927-3 estimates WDR using static wall-factor tables, limited in scope and unable to capture façade-specific geometry or sheltering. This study introduces a BIM‑native workflow that dynamically computes wall factor as a geometry‑derived exposure fraction, evaluated per façade cell via ray tracing and power‑law‑based cell‑level height‑scaling factorization. Implemented in Revit, the method automates ISO corrections for terrain, topography, and obstruction, and outputs exposure fraction, wall indices, and catch ratio with façade-resolved visualization. For the cases studies presented, the BIM-Ray Tracing approach (mean absolute errors 0.03–0.06), achieved accuracy close to CFD and outperformed ISO 15927-3 with runtimes suitable for early design. While turbulence and edge recirculation remain better addressed by CFD, the workflow enables exposure mapping, rule-based checks, and integration with ISO 15686 service-life performance analysis.
Keywords: wind‑driven rain, ISO 15927‑3, BIM, Revit plugin, hygrothermal performance, rain impact simulation, ray tracing, building performance modelling, WDR index
Published in RUP: 21.04.2026; Views: 600; Downloads: 15
Full text (9,77 MB)
This document has more files! More... |
6. BIM-based framework for estimating service life duration of wood construction elements under environmental exposureRichard Acquah, Jonas Niklewski, Anna Malgorzata Sandak, Jakub Michal Sandak, 2026, original scientific article Abstract: As the construction industry adopts more data-driven and sustainable practices, Building Information Modelling (BIM) is increasingly used for energy analysis, lifecycle management, and maintenance planning. However, its integration with service life performance analysis especially for wood, a material susceptible to environmental degradation remains limited. This study presents a BIM-based framework that incorporates wood-specific parameters such as environmental exposure, material properties, and design detailing to estimate the service life of wood construction elements. The framework is structured using ISO 15,686–4 principles and implemented through custom Industry Foundation Classes (IFC) property sets. A Revit plugin developed in C# integrates the model into the BIM environment. A case study of a wooden playhouse is used as a proof-of-concept to demonstrates the framework’s ability to evaluate the impact of design, material, and environmental factors on service life. The results confirm that the framework supports service life prediction and enhances decision-making for wood-based construction. Twenty-one-month observations align with predicted results. However, long-term (2–9 year) predictions remain unvalidated, requiring extended monitoring. By integration of the service life prediction for fungal decay into BIM it offers a practical and scalable tool to support service life–informed design and planning for wood structures.
Keywords: service life prediction, wood material durability, environmental exposure, wood 28 construction, sustainable construction, building information modelling (BIM)
Published in RUP: 24.11.2025; Views: 871; Downloads: 22
Full text (9,65 MB)
This document has more files! More... |
7. Push-out resistance of threaded wooden dowels in cross-laminated timber with hardwood cross-layerLei Han, Mohammad Derikvand, Jakub Michal Sandak, Martin Hladnik, Dick Sandberg, Andreja Kutnar, 2025, original scientific article Abstract: Europe is experiencing a shift in timber resource availability, with a decline in softwoods and an increase in hardwoods, creating a need to explore the utilisation of hardwoods, particularly in construction, where softwoods have traditionally been predominant. This research aimed to assess the potential of using hardwood in hybrid, doweled cross-laminated timber (DCLT) fabricated with pre-dried threaded beech dowels. The objective was to evaluate the push-out resistance of beech dowels in a three-layer DCLT with spruce in the outer longitudinal layers and beech, poplar, or spruce in the cross-layer. The DCLT specimens were conditioned at various temperatures and relative-humidity (RH) levels before the push-out test. The specimens with beech cross-layer exhibited a higher push-out resistance than those made entirely of spruce. In contrast, using poplar in the cross-layer showed no considerable difference in push-out resistance compared to using spruce. Exposure to 70 °C and 10% RH for three days decreased the push-out resistance in all groups due to extreme shrinkage of the lamellae, whereas exposure to 20 °C and 65% RH for either 60 days or 240 days resulted in higher push-out resistance for DCLT with a beech cross-layer.
Keywords: DCLT, underutilised species, hardwood, dowel
Published in RUP: 12.09.2025; Views: 1036; Downloads: 13
Full text (1,60 MB)
This document has more files! More... |
8. |
9. Feasibility of portable NIR spectrometer for quality assurance in glue-laminated timber productionJakub Michal Sandak, Peter Niemz, Andreas Hänsel, Juana Mai, Anna Malgorzata Sandak, 2021, original scientific article Keywords: near infrared spectroscopy, glue-laminated timber, glulam, delamination, quality assurance
Published in RUP: 18.10.2021; Views: 5305; Downloads: 27
 Link to full text |
10. |
