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In this paper an efficient procedure for obtaining a cohesive law for Mode I timber fracture (crack opening), based on the Double Cantilever Beam (DCB) tests is given. DCB tests were performed on ten European spruce specimens in order to determine the energy release rate vs crack length (R curves). Two crucial parameters - crack length during the experiment and the crack tip opening displacement were obtained using 2D Digital Image Correlation (DIC) technique. In order to determine accurate fracture resistance (R curve), procedure which includes calculating cumulative released energy was employed. The cohesive law for Mode I fracture of wood was obtained by differentiation of the strain energy release rate as a function of the crack tip opening displacement. This cohesive law is further implemented in the successful numerical modelling of failure modes in large-scale end-notched glulam beams which were experimentally tested in four-point bending configuration.

Bioadhesives derived from biomass are steadily gaining spotlight as substitutes for formaldehyde-based resins in the adhesive industry. However, there is a need to develop novel water-resistant bioadhesives with high adhesive and cohesive strengths because the currently available biomaterial-based adhesives have low mechanical strength. In this study, a complex coacervate was prepared easily by mixing silk fibroin and tannic acid to produce a bioadhesive with high adhesive and cohesive strengths as well as water resistance. The silk fibroin-tannic acid coacervate adhered well to various substrates, and its adhesive strength according to the type of substrate and water contact angle were evaluated comparatively. In particular, the adhesive strength of this adhesive on a wood substrate was systematically analyzed by varying different experimental parameters (relative humidity, surface roughness of the substrate, water stability, and pH). This cost-effective coacervate is applicable as an eco-friendly wood adhesive.

Polymer shape-memory aerogels (PSMAs) are prospects in various fields of application ranging from aerospace to biomedicine, as advanced thermal insulators, actuators, or sensors. However, the fabrication of PSMAs with good mechanical performance is challenging and is currently dominated by fossil-based polymers. In this work, strong, shape-memory bio-aerogels with high specific surface areas (up to 220 m2/g) and low radial thermal conductivity (0.042 W/mK) were prepared through a one-step treatment of native wood using an ionic liquid mixture of [MTBD]+[MMP]−/DMSO. The aerogel showed similar chemical composition similar to native wood. Nanoscale spatial rearrangement of wood biopolymers in the cell wall and lumen was achieved, resulting in flexible hydrogels, offering design freedom for subsequent aerogels with intricate geometries. Shape-memory function under stimuli of water was reported. The chemical composition and distribution, morphology, and mechanical performance of the aerogel were carefully studied using confocal Raman spectroscopy, AFM, SAXS/WAXS, NMR, digital image correlation, etc. With its simplicity, sustainability, and the broad range of applicability, the methodology developed for nanoscale reassembly of wood is an advancement for the design of biobased shape-memory aerogels.

Anaerobic digestion of organic waste results in production of biogas and a nutrient-rich digestate that has an established use as fertilizer in plant production. This study evaluated use of anaerobic digestate based on a high concentration of organic household waste as a fertilizer in sawdust-based production of oyster mushrooms (Pleurotus ostreatus). Inclusion of 0.5 L of anaerobic digestate (AD) per kg sawdust gave similar productivity in terms of biological efficiency (79.5 +/- 5.4 %), and protein concentration (24.7 +/- 2.4 % of dry weight (dw)) as standard mushroom substrate (78.1 +/- 5.3 %, and 21.9 +/- 3.0 % of dw, respectively). However, mushroom growth was impaired at the highest concentration of anaerobic digestate tested, 1 L digestate per kg dw sawdust. Comparison of the AD-fertilized substrate with a mushroom substrate with standard components (sawdust, wheat bran, calcium sulfate) and with similar C/N-ratio revealed some differences in elemental composition of the fruiting bodies, with an major increase in sodium concentration for the AD-fertilized substrate compared with the standard substrate (413.3 +/- 28.9 and 226.7 +/- 30.6 mg kg(-1) dw, respectively). This difference can be explained by high sodium concentration in the anaerobic digestate, most likely due to inclusion of food scraps from households and restaurants in the biodigester feedstock. Screening of both substrates for a total of 133 micro -pollutants revealed that total sum of micropollutants was significantly higher in the AD-fertilized substrate (258 +/- 12 ng/g dw substrate) than in the standard substrate (191 +/- 35 ng/g dw substrate). Nitrogen losses during preparation of the AD-fertilized substrate were negligible.

Wood burning contributes to indoor and ambient particulate matter (PM) pollution and has been associated with increased morbidity and mortality. Here, we present an integrated methodology that allows to generate, sample, and characterize wood smoke derived from different moisture contents and representative combustion conditions using pine wood as a model. Flaming, smoldering, and incomplete combustion were assessed for low-moisture pine, whereas both low-moisture pine and high-moisture pine were investigated under flaming conditions. Real-time monitoring of carbon monoxide, volatile organic compounds, and aerosol number concentration/size in wood smoke was performed. The PM was size-fractionated, sampled, and characterized for elemental/organic carbon, organic functional groups, and inorganic elements. Bioactivity of PM was assessed by measuring the sterile alpha motif (SAM) pointed domain containing ETS (E-twenty-six) transcription factor (SPDEF) gene promoter activity in human embryonic kidney 293 (HEK-293T) cells, a biomarker for mucin gene expression. Findings showed that moisture content and combustion condition significantly affected the organic and inorganic elemental composition of PM

Pojavom građevinarstva kao djelatnosti, ljudi počinju koristiti prirodne materijale poput kamena, drva, bambusa, opeke i slame za izgradnju svojih utočišta. Ovi materijali su prirodni, održivi i ne izazivaju štetne posljedice na okoliš. Međutim,dolaskom industrijske ere i povećanom potražnjom za građevinskim proizvodima, započela je masovna proizvodnja industrijskih materijala kako bi se ubrzala i optimizirala gradnja. Kao posljedica toga, građevinska industrija postala je jedan od najvećih zagađivača na svijetu. Cilj ovog rada je prikazati tradicionalne materijale i analizirati prednosti i nedostatke njihove upotrebe u građevinskoj industriji. Nadalje, u ovom radu istražuju se suvremene primjene tradicionalnih ekoloških materijala u arhitekturi, čime se pokazuje kako se suvremena arhitektura uspješno može kombinirati s tradicionalnim materijalima., Ever since construction began as an activity, people have turned to natural materials such as stone, wood, bamboo, brick, and straw to build their shelters. These materials are natural, sustainable, and do not cause harmful effects on the environment. However, with the onset of the industrial era and the increased demand for construction products, mass production of industrial materials began to accelerate and optimize construction. As a result, the construction industry has become one of the world's largest polluters. The aim of this paper is present traditional materials and to analyze the advantages and disadvantages of their use in construction industry. Furthermore, this paper explores contemporary use of traditional ecological materials in architecture, which shows how contemporary architecture can be successfully combined with traditional materials.

European oak logs (Quercus robur, Quercus petraea) from the 15th auction of valuable logs in Slovenj Gradec in 2021 were included in the study. Of the 1,318 auctioned logs, 78 were randomly selected and visually graded into quality classes (A, B, C) according to the National Grading Rules (2017). In parallel, we analysed the wood growth dendrochronologically and the acoustic properties of the logs using the longitudinal vibration resonance method. The logs with the best quality had a larger diameter and, on average, wider annual rings. We confirmed the correlation between the visually determined quality and the obtained price of the logs. Longitudinal vibration velocity (v) and relative acoustic conversion efficiency (RACE) were positively correlated with log quality and price. The frequency spectra of the low-quality logs differed from the theoretical spectra. This study confirms the feasibility of non-destructive acoustic methods for evaluating oak log quality. V raziskavo smo vključili hrastovo hlodovino (Quercus robur, Quercus petraea) s 15. dražbe vrednejših sortimentov okroglega lesa v Slovenj Gradcu v letu 2021. Naključno smo izbrali 78 od 1318 licitiranih hlodov in jih skladno z veljavnim Pravilnikom o merjenju (2017) vizualno razvrstili po kakovosti (A, B, C). Vzporedno smo dendrokronološko analizirali priraščanje lesa ter z metodo frekvenčnega odziva pri vzdolžnem vzbujanju še akustične lastnosti hlodovine. Najkvalitetnejša hlodovina je bila večjih premerov, z več in povprečno širšimi branikami. Potrdili smo povezavo med vizualno določeno kakovostjo in doseženo ceno hlodovine. Hitrost vzdolžnega nihanja (v) in relativna učinkovitost akustične pretvorbe (RACE) sta bili s kakovostjo in ceno hlodovine pozitivno povezani. Frekvenčni spektri pri hlodovini nižje kakovosti odstopajo od teoretičnih. Raziskava je potrdila možnost uporabe nedestruktivnih akustičnih metod za oceno kakovosti hrastove hlodovine.

The work is part of the R&D&I Project PID2020-112954RA-I00 funded by MCIN/AEI/10.13039/501100011033. Publisher Copyright: © 2023 The Authors Fracture characterisation under mode I loading of Eucalyptus globulus Labill. bonded joints with one-component polyurethane adhesive (1C-PUR) is addressed in this work. The objective is to estimate the cohesive law representative of the fracture behaviour of these joints. A direct and two inverse procedures were employed to determine the softening laws. The direct method is based on local measurement of crack tip displacements using digital image correlation in the course of Double Cantilever Beam (DCB) tests, while the inverse methods rely on load–displacement data and on load-crack tip opening displacement relations by finite element modelling. It was verified that consistent results can be obtained from the three methodologies leading to the conclusion that the classical inverse procedure is the most appealing one owing to its simplicity. publishersversion published

Se realizo el estudio patológico con propósito educativo de una vivienda ubicada en la ciudad de Pasto, departamento de Nariño. El objetivo principal es desarrollar un documento técnico donde se recopilo los conocimientos adquiridos en la clase de historia clínica y diagnóstico, en donde se realizó el diagnóstico y presentación de las patologías que el proyecto contiene en su estructura. A lo largo de este informe vamos a enumerar y explicar las lesiones que se pueden producir en la vivienda, es importante saber identificar estas lesiones lo antes posible y ser capaces de determinar el alcance del daño. Esto nos ayudará a establecer un diagnóstico lo más acertado posible de sus causas y proyectar la intervención más adecuada. In situ se realizó una inspección visual de la estructura para identificar los elementos principales y secundarios, así como las dimensiones reales y las piezas correspondientes a estudiar. Con esta inspección visual se busca detectar diversas patologías, las cuales van a hacer recopiladas en fichas técnicas y planos. A pathological study was carried out for educational purposes in a house located in the city of Pasto, department of Nariño. The main objective is to develop a technical document where the knowledge acquired in the clinical history and diagnosis class was compiled, where the diagnosis and presentation of the pathologies that the project contains in its structure was made. Throughout this report we are going to list and explain the injuries that can occur in the home, it is important to know how to identify these injuries as soon as possible and be able to determine the extent of the damage. This will help us establish the most accurate diagnosis possible of its causes and project the most appropriate intervention. In situ, a visual inspection of the structure was carried out to identify the main and secondary elements, as well as the real dimensions and the corresponding pieces to be studied. With this visual inspection, the aim is to detect various pathologies, which will be compiled in technical sheets and plans. Especialista en Patología de la construccion Especialización

This research deals with the processing of wood using a circular saw, which is associated with several risks and factors that affect the wood-splitting process. One of them is the wear of the teeth of the saw blade that change the magnitude of the cutting forces. The aim of this study is to compare real measured values and theoretical values when processing Norway spruce wood using two types of saw blades, i.e., sintered carbide (SC) and high-speed steel (HSS), with a diameter of 600 mm and 54 and 56 teeth, respectively. Experimental measurements were carried out on a special test device with the possibility of moving the tested wood into the cutting devices and a simple saw blade replacement system. The results of the contributions show significant differences, based on defined factors which represent the cutting and feed speed, which are supported by FEM analysis of cutting forces in the process of cutting wood—when changing the design of the saw blade. The results of the experiment show that the cutting conditions (cutting speed and feed speed) do not have a significant effect on the size of the cutting forces. The theoretical and real stress values for HSS discs ranged from 14 to 22 MPa. Significantly larger differences were recorded for discs with SC, where the real values of the maximum stresses were around 14 MPa and the theoretical ones around 25 MPa. When cutting spruce with a disc with SC slices, the maximum values of the theoretical cutting forces were in the range of 76 to 94 N and the maximum values of the measured cutting forces were in the range of 40 to 44 N.

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 importance of renewable and environmentally acceptable materials in the construction industry is increasing. Wood is one of the most important construction materials and its use in building applications has further expanded in recent decades, mainly due to the development of modern composites, firstly glue lam, OSB (Oriented Strand Board), LVL (Laminated Veneer Lumber) and a considerable breakthrough was later achieved with the development of cross-laminated timber. In order to enable even more extensive and reliable use of wood in outdoor applications, factors affecting a wood’s service life need to be understood. It is well known that fungal degradation of wood is predominantly affected by temperature and wood moisture content. In order to elucidate the influence of these two factors, long-term monitoring of temperature, relative humidity and moisture content at the newly-built Annex of the Department of Wood Science and Technology was carried out. The Annex is designed from CLT composites and glue-lam beams and was finished in December 2015. The results clearly show that microclimatic conditions in the monitored building in the first years of use are far below the limit required for fungal decay or mould growth.

To use wood as a structural element in vehicles, it is necessary to measure its physical properties locally in order to deduce its mechanical behaviour. Density is one of the characteristics that influences the most the mechanical properties, and it is on its measurement that this study will focus, using a technology that is still little studied for this application: terahertz radiation. Measurements using a Terahertz radar on samples will allow to obtain maps of the optical index and absorption coefficient, these values being linked to the density of the samples. The present study will consider wood species with various global densities and exhibiting local density pattern (growth rings) to assess the prediction of the density.

At present, the popularity of timber as a structural material is booming. However, the current knowledge on disproportionate collapse prevention and extreme loading of timber buildings is scarce. To prevent disproportionate and progressive collapse, catenary action is an important mechanism, where the axial capacity of bending members is activated. Because of the brittle behavior of timber in the relevant failure modes, it can only achieve catenary action via strengthening. In this paper, analytical expressions are derived for the elastic, plastic, and catenary capacity of laterally loaded wood and timber beams with a tension-side strip reinforcement. A load-path dependent M-N interaction diagram with damage accumulation explains the ultimate catenary capacity and the transition between the bending- and catenary-dominated load-carrying mode. The analytical expressions are validated and discussed based on tests on beech clearwood specimens reinforced with carbon fibers in a polyurethane matrix. Furthermore, a case study on glued laminated timber beams is presented to demonstrate the potential of reinforcing timber beams subjected to extreme loading., Construction and Building Materials, 385, ISSN:0950-0618