Articoli di riviste: "Timber decay"

1

Singh, Jagjit, Peter Mann e Nia White. "Timber Decay: Causes and Remedies". Structural Engineering International 6, n. 3 (agosto 1996): 200–202. http://dx.doi.org/10.2749/101686696780495464.

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Lothian, M. T. "Surveying for timber decay and damp". Structural Survey 8, n. 4 (aprile 1990): 407–15. http://dx.doi.org/10.1108/eum0000000003232.

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Hutton, T. C., H. Lloyd e J. Singh. "The environmental control of timber decay". Structural Survey 10, n. 1 (gennaio 1992): 5–20. http://dx.doi.org/10.1108/02630809210031672.

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4

Brischke, Christian, Gry Alfredsen, Miha Humar, Elena Conti, Laurie Cookson, Lukas Emmerich, Per Otto Flæte et al. "Modelling the Material Resistance of Wood—Part 3: Relative Resistance in above- and in-Ground Situations—Results of a Global Survey". Forests 12, n. 5 (8 maggio 2021): 590. http://dx.doi.org/10.3390/f12050590.

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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.

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Richard Avent, R. "Decay, Weathering and Epoxy Repair of Timber". Journal of Structural Engineering 111, n. 2 (febbraio 1985): 328–42. http://dx.doi.org/10.1061/(asce)0733-9445(1985)111:2(328).

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Singh, Jagjit, e Nia White. "Timber Decay in Buildings: Pathology and Control". Journal of Performance of Constructed Facilities 11, n. 1 (febbraio 1997): 3–12. http://dx.doi.org/10.1061/(asce)0887-3828(1997)11:1(3).

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7

Kumar, N. Praveen, e Arun Arya. "Timber Degrading Fungi in Sawmills of Gujarat, India". International Letters of Natural Sciences 7 (dicembre 2013): 13–22. http://dx.doi.org/10.18052/www.scipress.com/ilns.7.13.

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Timer decay is caused by primarily enzymatic activities of microorganisms. For the first time fungal diversity of timber degrading fungi was studied in Gujarat, India. Timber Degrading Fungi belonging to Aphyllophorales are economically important as many of these cause serious damage in sawmills of Gujarat. To find out the association of the timber degrading fungi and timber decay problems in sawmills a survey was conducted during 2007 to 2011 in different sawmills of 5 districts of Gujarat i.e. Vadodara, Ahmedabad, Bharuch, Rajkot and Jamnagar. In the present study teak wood present in sawmills was infected with 14 types of fungi in which Lenzites sterioides and Trametes versicolor damaged the wood severely was reported for the first time. In all 94 sawmills were surveyed, the 28 sawmills were from Vadodara, 29 from Ahmedabad, 12 from Bharuch, 21 from Rajkot and 4 from Jamnagar. Out of 94 sawmills survyed, 84 sawmills were having timber rotting fungi associated with wood. Maximum fifteen and thirteen fungal species were observed in saw mills of Chhani road, followed by 11 in Station road, 7 in Dhabhoi road and 6 in Harni, Vadodara. Fours woods uninfected are Beyo, Marinty, Ash, and Arjun. Fourteen different types of fungi were found associated with teak, followed by seven in pinus, madhuca, Acacia nilotica, six in babul, neem, four in tamarind, Pithacoelobium and three in mango, Eucalyptus, African Mahagoni, Kapoor, Peltophoram rouxburghii, Derris pinnata wood respectively. The commonly observed timber decaying fungi were Schizophyllum commune, Flavodon flavus and Ganoderma lucidum belonging to Basidiomycota. Ascomycota members included was Daldinia concentrica and Xylaria polymorpha.

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Kumar, N. Praveen, e Arun Arya. "Timber Degrading Fungi in Sawmills of Gujarat, India". International Letters of Natural Sciences 7 (17 dicembre 2013): 13–22. http://dx.doi.org/10.56431/p-ybb088.

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Timer decay is caused by primarily enzymatic activities of microorganisms. For the first time fungal diversity of timber degrading fungi was studied in Gujarat, India. Timber Degrading Fungi belonging to Aphyllophorales are economically important as many of these cause serious damage in sawmills of Gujarat. To find out the association of the timber degrading fungi and timber decay problems in sawmills a survey was conducted during 2007 to 2011 in different sawmills of 5 districts of Gujarat i.e. Vadodara, Ahmedabad, Bharuch, Rajkot and Jamnagar. In the present study teak wood present in sawmills was infected with 14 types of fungi in which Lenzites sterioides and Trametes versicolor damaged the wood severely was reported for the first time. In all 94 sawmills were surveyed, the 28 sawmills were from Vadodara, 29 from Ahmedabad, 12 from Bharuch, 21 from Rajkot and 4 from Jamnagar. Out of 94 sawmills survyed, 84 sawmills were having timber rotting fungi associated with wood. Maximum fifteen and thirteen fungal species were observed in saw mills of Chhani road, followed by 11 in Station road, 7 in Dhabhoi road and 6 in Harni, Vadodara. Fours woods uninfected are Beyo, Marinty, Ash, and Arjun. Fourteen different types of fungi were found associated with teak, followed by seven in pinus, madhuca, Acacia nilotica, six in babul, neem, four in tamarind, Pithacoelobium and three in mango, Eucalyptus, African Mahagoni, Kapoor, Peltophoram rouxburghii, Derris pinnata wood respectively. The commonly observed timber decaying fungi were Schizophyllum commune, Flavodon flavus and Ganoderma lucidum belonging to Basidiomycota. Ascomycota members included was Daldinia concentrica and Xylaria polymorpha.

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Udele, Kenneth E., Jeffrey J. Morrell e Arijit Sinha. "Biological Durability of Cross-Laminated Timber— The State of Things". Forest Products Journal 71, n. 2 (1 marzo 2021): 124–32. http://dx.doi.org/10.13073/fpj-d-20-00076.

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Abstract Cross laminated timber (CLT) is a mass timber product that is gaining popularity in construction within North America. CLT is made up of wood, a building material of biological origin. Therefore, these materials are at a risk of decay upon intrusion of moisture, a situation that could lead to loss of confidence in the material. Ensuring durability and optimum performance of building elements throughout their expected service life will require an understanding of the potential for decay and the possible consequences. This paper reviews the various possibilities of moisture intrusion in CLT, their potential effects on the physical and mechanical properties of CLT, and ultimately the associated biological decay risks. The paper concludes by enumerating variables that are critical and should be evaluated to completely understand decay in CLT panels, stemming from a thorough review of previous studies and methods used to evaluate decay in mass timber.

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Rickli, Christian, e Frank Graf. "Wildbachsperren aus Fichte und Tanne: Festigkeit und Pilzbefall in den ersten Jahren". Schweizerische Zeitschrift fur Forstwesen 165, n. 4 (1 aprile 2014): 79–86. http://dx.doi.org/10.3188/szf.2014.0079.

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Timber constructions in torrent control with Norway spruce and silver fir: wood quality and colonisation with decay fungi during the first years Timber is widely used for protection measures in torrent control. However, life span of woody constructions such as timber check dams is limited due to fungal decay. Only sparse scientific information is available on the long-term behaviour of timber structures and the colonisation with decay fungi. Related to this, in practice a controversial discussion has been going on if either Norway spruce (Picea abies) or silver fir (Abies alba) is more enduring and if bark removal increases resistance against fungal decay. In order to going into this matter, a series of 15 timber check dams built in 1996/1997 has been monitored. The constructions were alternatively realised with Norway spruce and silver fir, half of them each with remaining and removed bark, respectively. The scientific investigations included the documentation of colonisation with rot fungi and the identification of decayed zones with a simple practical approach as well as based on drilling resistance. Colonisation by decay fungi started three years after construction (e.g. Gloeophyllum sepiarium), two years later first parts with reduced wood resistance were detected. The protection measures were still fully functional sixteen years after construction although decay was found on all check dams but two. Wood quality was markedly better in watered sections compared to the occasionally dry lateral abutment sections, without showing clear differences in decay between logs of Norway spruce and silver fir. However, both the practical approach and the drilling resistance measurement suggest more defects on logs without bark. Further investigations and sound statistical analysis are needed to confirm the observed trends.

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Shakimon, Mohd Nizam, Rohana Hassan, Nor Jihan Abd Malek, Azman Zainal, Ali Awaludin, Nor Hayati Abdul Hamid, Wei Chen Lum e Mohd Sapuan Salit. "European Yield Model Exponential Decay Constant Modification for Glulam after Fire Exposure". Forests 13, n. 12 (28 novembre 2022): 2012. http://dx.doi.org/10.3390/f13122012.

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Many real-scale fire tests have been performed on timber connections to analyze the mechanical behavior of timber connections in previous years. However, little research focused on the bending performance of glued laminated (glulam) timber beam bolted connections after fire exposure. In this paper, the three-dimensional numerical model of the glulam timber beam bolted connections was developed and validated by experimental results. The model can simulate temperature evolution in the connections and their mechanical behavior. In the real-scale test, three (3) samples were prepared for a four-point bending test at normal temperature, while another three (3) samples were tested after exposure to a 30-min standard fire and cooled down to normal temperature. The results show the reduction of the load-carrying capacity before and after exposure to the standard fire by 23.9 kN (71.8%), 8.3 kN (26.1%), and 20.2 kN (47.6%) for bolt diameters of 12 mm, 16 mm, and 20 mm, respectively. The numerical model aims to conduct a parametric study and propose the modification of the exponential decay constant, k, for tropical glulam timber to predict the load-carrying capacity of the glulam timber beam bolted connections after exposure to standard fire.

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Vanpachtenbeke, Michiel, Jan Van den Bulcke, Joris Van Acker e Staf Roels. "Performance of wood and wood-based materials regarding fungal decay". E3S Web of Conferences 172 (2020): 20010. http://dx.doi.org/10.1051/e3sconf/202017220010.

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Due to the increasingly stringent energy efficiency requirements, timber frame houses are becoming more and more popular across Europe. Depending on the circumstances, timber frame walls might be exposed to high relative humidity or condensation conditions, leading to a risk of fungal degradation. In order to assess the durability of a timber frame construction in a reliable way, a clear view on the potential risk of fungal growth is essential. Various experiments are reported in literature to define the minimal moisture threshold for fungal decay, yet all very different in set-up and hence leading to contradictory conclusions. Therefore, the present paper aims at a contribution to a better understanding of the influence of moisture conditions on the onset and progress of wood decay in timber frame walls. Based on the information that is still lacking in international literature, a new test methodology has been elaborated within this work and is reported in this paper.

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Wilde, Ronald. "Reporting on timber decay in a condition survey". Journal of Building Appraisal 1, n. 1 (febbraio 2005): 47–62. http://dx.doi.org/10.1057/palgrave.jba.2940005.

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Sawata, Kei, e Yoshihisa Sasaki. "Lateral strength of nailed timber connections with decay". Journal of Wood Science 64, n. 5 (6 giugno 2018): 601–11. http://dx.doi.org/10.1007/s10086-018-1734-8.

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Brischke, Christian, e Linda Meyer-Veltrup. "Modelling timber decay caused by brown rot fungi". Materials and Structures 49, n. 8 (13 ottobre 2015): 3281–91. http://dx.doi.org/10.1617/s11527-015-0719-y.

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16

Giuriani, Ezio, Alessandra Marini, Stefania Cominelli e Alessandra Gubana. "The Penetration Test to Evaluate Wood Decay after 20 Years Timber Structure Assessment Experience". Advanced Materials Research 778 (settembre 2013): 201–8. http://dx.doi.org/10.4028/www.scientific.net/amr.778.201.

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The Wood Penetration Test described in the present paper was set up almost 20 years ago to evaluate the timber vaulted roof decay of Palazzo della Loggia in Brescia (Italy). The test can be regarded as an extension to timber structures of the dynamic soil penetration test, as it is based on the insertion into timber structural members of a steel graduated rod, which advances by means of repeated constant energy blows transmitted by a rebound hammer. The test makes possible to distinguish between different degrees of decay as a function of the number of blows necessary for each centimetre layer penetration. This technique proved to be effective and reliable for investigating the extent and depth of wood decay and thanks to the assessment campaign the possibility of restoring the ancient vault gained strength. The test was then frequently proposed and adopted by the Structural Engineering Laboratory of Brescia University and several ancient building timber structures were checked by means of this methodology. Some significative examples will be briefly described. A recent investigation has been done on the rim beams at the basis of the Palazzo della Loggia timber vault by using the penetration test and the Resistograph and the comparison of the results is also illustrated. The test is easy to perform and the output data can be interpreted very clearly by structural engineers: it is possible to determine the depth of the decayed layers and consequently the reliable dimensions of the resisting timber sections.

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Harju, Anni M., e Martti Venäläinen. "Measuring the decay resistance of Scots pine heartwood indirectly by the Folin-Ciocalteu assay". Canadian Journal of Forest Research 36, n. 7 (1 luglio 2006): 1797–804. http://dx.doi.org/10.1139/x06-074.

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To exploit the variation in the natural durability of heartwood timber, screening of a large number of trees or timber is necessary. We suggest that the concentration of total phenolics, measured by the Folin–Ciocalteu (FC) assay, can be used to supplement or even replace in vitro decay tests for screening the variation in the resistance of Scots pine (Pinus sylvestris L.) heartwood timber against the brown-rot fungus Coniophora puteana (Schum. ex Fr.). We screened the juvenile heartwood of 520 Scots pine trees with the FC assay. Samples from 40 trees, with total phenolics concentrations ranging from 1.9 to 21.7 mg tannic acid equivalents (TAE)/g of heartwood, were subjected to an in vitro decay test. The correlation (r) between the total phenolics concentration and mass loss was –0.82 (p < 0.001) in the 7 week long decay test. The relationship was expressed with a linear regression equation: mass loss (mg/g) = 487 – 25 × concentration of total phenolics (mg TAE/g). This strong relationship could be exploited by replacing the decay test with the FC assay to more rapidly assess the durability of wood products.

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Macchioni, Nicola, Massimo Mannucci, Roberto Olmi, Sabrina Palanti e Cristiano Riminesi. "Microwave Reflectometric Tool for Non-Destructive Assessment of Decay on Timber Structures". Advanced Materials Research 778 (settembre 2013): 281–88. http://dx.doi.org/10.4028/www.scientific.net/amr.778.281.

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Timber structures can be degraded during their life both by structural problems and, mainly, by biological degradation factors like fungi, and insects (Coleoptera and termites). The occurrence of these biodegradation agents leads, in the absence of appropriate maintenance interventions, to the loss of their structural integrity. Furthermore, if these biological agents decay old buildings, the loss of mechanical resistance of timber structures can be added to loss of cultural heritages. Just in these contexts an early evaluation of decay is crucial to design remedial treatments and a less invasive restoration intervention. This work presents a new microwave diagnostic system for the in situ evaluation of timber structures based on microwave reflectometry, i.e on the measurement of the microwave reflection coefficient as a function of frequency. The continuous-wave (CW) microwave signal is launched by a double-ridged antenna, which also measures the wave reflected by the material under investigation. The measurement system allows diagnosing the effects of biodegradation during a first quick survey in a non-destructive and non-invasive manner. Measurements on laboratory models demonstrated the feasibility of the method. Results obtained on timber beam sections, compared with the findings of traditional investigation methodologies, demonstrate the potentiality of microwave reflectometry, suggesting its usefulness for decay detection and as a support to invasive diagnostic tools.

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March, Susan D. Turner, J. Bryan Blundell e Brian Ridout. "Timber Decay in Buildings: The Conservation Approach to Treatment". APT Bulletin 31, n. 4 (2000): 57. http://dx.doi.org/10.2307/1504679.

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Ridout, Brian. "Timber Decay in Buildings: The Conservation Approach to Treatment". APT Bulletin 32, n. 1 (2001): 58. http://dx.doi.org/10.2307/1504694.

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Isaksson, Tord, Christian Brischke e Sven Thelandersson. "Development of decay performance models for outdoor timber structures". Materials and Structures 46, n. 7 (2 novembre 2012): 1209–25. http://dx.doi.org/10.1617/s11527-012-9965-4.

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Ridout, Brian. "The Treatment of Timber Decay into the 21st Century". Journal of Architectural Conservation 4, n. 3 (gennaio 1998): 7–21. http://dx.doi.org/10.1080/13556207.1998.10785222.

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SAWATA, Kei. "Effect of decay on performance of mechanical timber joints". MOKUZAI HOZON (Wood Protection) 41, n. 1 (2015): 2–7. http://dx.doi.org/10.5990/jwpa.41.2.

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Ferro, Fabiane Salles, Julio César Pigozzo, Diego Henrique de Almeida, Felipe Hideyoshi Icimoto, Laurenn Borges de Macedo, Carlito Calil Junior e Francisco Antonio Rocco Lahr. "Nondestructive Evaluation of Timber Columns of a Capela Bridge in the State of São Paulo, Brazil". Advanced Materials Research 778 (settembre 2013): 258–64. http://dx.doi.org/10.4028/www.scientific.net/amr.778.258.

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After years of exposure in environmental conditions, the wood is subject to decay by chemical, mechanical, physical and biological agents. Consequently its physical and mechanical properties can be reduced, affecting their use. Timber used in bridge sustention columns is subject to intense decay process, mainly in outcrop area (area in contact to the ground), the most critical situation, because of the best combination of humidity e oxygen, factors that provide wood decay organisms. Decay process can be minimized with preventive maintenance, as wood impregnation with preservatives, before installation of the timber. After wood is installed, a periodical maintenance is necessary to conserve and prolong its life time. Thus, the aim of this study is to evaluate degradation occurred in timber columns used in Capela Bridge sustention, built with mixed system of wood and concrete, after 10-years-old of use. Located in Piracicaba - SP, Brazil, the bridge was made with Corymbia citriodora CCA-treated. The columns strength and degradation conditions were evaluated in 2 points with isntrumented driller. Point A was approximately 1,5 m of the ground and point B was in outcrop area. Instrumented driller results showed that all the columns, in both points, presented good strength and had no degradation level.

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Alfredsen, Gry, Annica Pilgård e Carl Gunnar Fossdal. "Characterisation of Postia placenta colonisation during 36 weeks in acetylated southern yellow pine sapwood at three acetylation levels including genomic DNA and gene expression quantification of the fungus". Holzforschung 70, n. 11 (1 novembre 2016): 1055–65. http://dx.doi.org/10.1515/hf-2016-0009.

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Abstract One way to protect timber in service against basidiomycete deterioration is by means of acetylation via reaction with acetic anhydride. The reason why acetylated wood (WAc) is resistant against decay fungi is still not exactly understood. The aim of this study was to contribute to this field of science, and Postia placenta colonisation after 4, 12, 20, 28 and 36 weeks was observed at three acetylation levels of Pinus spp. sapwood. Mass loss (ML) and wood moisture content (MC) data reflected the acetylation levels. The initial equilibrium MC (EMC) proved to be a good indicator of subsequent ML. Genomic DNA quantification showed P. placenta colonisation in all samples, also in samples where no ML were detectable. The number of expressed gene transcripts was limited, but the findings supported the results of previous studies: WAc seems to have some resistance against oxidative mechanisms, which are part of the metabolism of P. placenta. This leads to a delay in decay initiation, a delay in expression of genes involved in enzymatic depolymerisation, and a slower decay rate. The magnitudes of these effects are presented for each acetylation level. The data also imply that there is no absolute decay threshold at high acetylation levels, but instead a significant delay of decay initiation and a slower decay rate.

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Stirling, Rod, Robert M. Knudson, Martin W. Feng e Paul I. Morris. "Field Performance of Glued Laminated Timber (Glulam) Manufactured from Thin Treated Lamina". Forest Products Journal 72, n. 1 (1 gennaio 2022): 29–36. http://dx.doi.org/10.13073/fpj-d-21-00067.

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Abstract Glued Laminated Timber, commonly referred to as Glulam, is an important structural wood product, suitable for use in exterior applications provided it is protected against decay by building design, natural durability, or treatment. Bonding treated lamina made from refractory species is challenging because resurfacing after treatment can remove much of the treated zone and create a waste disposal challenge. It was hypothesized that use of roll-pressing rather than resurfacing could address this. When an adhesive modifier was used to prevent the adverse effects of wood preservatives on adhesive bonding, treated lamina that were replaned before gluing had similar shear strength to untreated planed lamina. However, the treated lamina that were roll-pressed before gluing had lower shear strength than the replaned lamina. The consequence of this weakening was evident in an above-ground field test where delamination was observed in several test units after 12 years of exposure. Decay resistance was evaluated in above-ground, ground contact, and ground proximity tests. The decay resistance of treated glulam was high with only low levels of decay reported in all tests, while untreated controls showed advanced decay or failure. Yellow cedar glulam, included as a reference in the ground proximity test, showed moderate decay after 10 years of exposure.

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Rahman, Anisur, Gopi Chattopadhyay e M. Jahangir Hossain. "Maintenance Decisions for Inground_newline Decay of Power-Supply Timber Poles". IEEE Transactions on Power Delivery 31, n. 3 (giugno 2016): 1106–11. http://dx.doi.org/10.1109/tpwrd.2015.2424428.

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Brites, Ricardo D., Luís C. Neves, J. Saporiti Machado, Paulo B. Lourenço e Hélder S. Sousa. "Reliability analysis of a timber truss system subjected to decay". Engineering Structures 46 (gennaio 2013): 184–92. http://dx.doi.org/10.1016/j.engstruct.2012.07.022.

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Li, Peng, Na Yang e Yang Wang. "Research on Structural Present State and Damage Reasons of Ancient Tibetan Buildings". Applied Mechanics and Materials 351-352 (agosto 2013): 1652–56. http://dx.doi.org/10.4028/www.scientific.net/amm.351-352.1652.

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Due to different structural form, surrounding environment and external force, the damage of Ancient Tibetan buildings reflects its own characteristics. In this paper, the damage types of ancient Tibetan buildings are classified based on fieldwork, and then the damage reasons are studied. The main failure modes of ancient Tibetan buildings are damages and deformations of timber components and walls, including cracking and deflection of beams, column cracking, Queti slating, decay and cracking of rafters and cracking in walls. The damage reasons of ancient Tibetan buildings can be attributed to three aspects: degradations of timbers, structural defects and long-term external forces.

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Venäläinen, Martti, Anni M. Harju, Nasko Terziev, Tapio Laakso e Pekka Saranpää. "Decay resistance, extractive content, and water sorption capacity of Siberian larch (Larix sibirica Lebed.) heartwood timber". Holzforschung 60, n. 1 (1 gennaio 2006): 99–103. http://dx.doi.org/10.1515/hf.2006.017.

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Abstract The aim of this study was to find chemical or physical properties of Siberian larch heartwood timber that correlate with the variation in decay resistance. Juvenile heartwood from 24-year-old grafts of 15 clones was exposed to three brown-rot fungi according to the standard in vitro decay test (European standard EN 113). The mass losses caused by the brown rot fungi Coniophora puteana, Poria placenta, and Gloeophyllum trabeum were 20%, 28% and 17% of the dry mass, respectively. The average mass loss over the three fungi had a strong negative correlation with the concentration of taxifolin (r=–0.673, P=0.006), as well as with the concentration of total phenolics determined by the Folin-Ciocalteu assay (r=–0.677, P=0.006). Thus, the concentration of flavonoids is a promising property for indirect measurement of the decay resistance of Siberian larch timber. The most abundant heartwood extractives, arabinogalactans, had a non-significant relationship with the decay resistance, but their concentration correlated positively with the capacity of the wood to adsorb water (r=0.736, P=0.002). The hygroscopic properties of the wood or the wood density were not associated with the decay resistance.

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Merganičová, K., e J. Merganič. "Coarse woody debris carbon stocks in natural spruce forests of Babia hora". Journal of Forest Science 56, No. 9 (30 settembre 2010): 397–405. http://dx.doi.org/10.17221/11/2010-jfs.

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Although coarse woody debris (CWD) represents one of the major carbon pools in natural forest ecosystems, little information is available about its CWD carbon stocks. This study demonstrates the importance of proper estimation of carbon stocks in CWD, which accounts for the decay process of CWD, on an example of a natural mountainous spruce forest located in Central Europe. The study accounts for aboveground coarse woody debris including standing dead trees, lying deadwood, and naturally formed stumps. Basic mensurational information (diameter, height, decay class) about dead wood was collected in the field during the inventory of the forests of the nature reserve Babia hora. The data were used for the calculation of CWD timber volume. In the next step, CWD timber volume was converted to carbon stock using the carbon proportion of 50.1% and density values of decay classes derived from the information published elsewhere. The analysis revealed that when CWD timber volume was converted to carbon stocks using the basic wood density of fresh wood, C stocks were overestimated by 40% or more depending on the developmental stage and elevation. The results also revealed that as the elevation increases, CWD carbon stocks decrease and the differences between the developmental stages diminish.

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A.R, Noor Azrieda, Salmiah U e Rahim S. "Comparison of Accelerated Decay and Graveyard Test on Selected Malaysian Timber Species". Journal of Tropical Resources and Sustainable Science (JTRSS) 3, n. 1 (14 dicembre 2015): 238–41. http://dx.doi.org/10.47253/jtrss.v3i1.702.

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The natural durability of timber may be defined as ‘inherent resist ance of timber to attackby wood deteriorat ion agents such as wood decay ing fungi and wood destroying insects’. In Malay sia, natural durabilit y of t imber is det ermined using a ‘gravey ard’ test . The average time taken for this test is more than 10 years. The results of this test method donot provide information on longevity (service life) either out of ground contact, or inother geographical locations. Comparison of natural durability requires the use ofstandard test method where for example in Europe, the accepted laboratory method is EN350-1. This paper briefly describes the rating of natural durability based on comparisonresults of the two test methods stated i.e the exterior graveyard test and the interior laboratory test.

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Goodell, Barry, Jerrold E. Winandy e Jeffrey J. Morrell. "Fungal Degradation of Wood: Emerging Data, New Insights and Changing Perceptions". Coatings 10, n. 12 (11 dicembre 2020): 1210. http://dx.doi.org/10.3390/coatings10121210.

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Wood durability researchers have long described fungal decay of timber using the starkly simple terms of white, brown and soft rot, along with the less destructive mold and stain fungi. These terms have taken on an almost iconic meaning but are only based upon the outward appearance of the damaged timber. Long-term deterioration studies, as well as the emerging genetic tools, are showing the fallacy of simplifying the decay process into such broad groups. This paper briefly reviews the fundamentals of fungal decay, staining and mold processes, then uses these fundamentals as the basis for a discussion of fungal attack of wood in light of current knowledge about these processes. Biotechnological applications of decay fungi are reviewed, and an overview is presented on how fungi surmount the protective barriers that coatings provide on surfaces. Advances in biochemical analyses have, in some cases, radically altered our perceptions of how wood is degraded, and even the relationships between fungal species, while other new findings have reinforced traditional perspectives. Suggestions for future research needs in the coatings field relative to enhanced fungal and environmental protection are presented.

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34

Wang, Xi Ping, Marko Teder e James Wacker. "Condition Assessment of the Timber Structures of a Century-Old Industrial Building Using a Nondestructive Inspection Procedure". Advanced Materials Research 778 (settembre 2013): 840–48. http://dx.doi.org/10.4028/www.scientific.net/amr.778.840.

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This paper reports an in situ inspection project conducted on heavy timber structures of a century-old industrial building at a paper manufacturing facility. A nondestructive inspection procedure was employed to evaluate the true condition of the heavy timbers that serve as the main framing structure of the building. The on-site investigation involved monitoring of the microclimate environment resulting from the paper machine operations, wood species identification, wood moisture content measurements, and internal decay detection using sounding, stress wave timing, and resistance micro-drilling methods. The testing results revealed that numerous locations were in poor condition indicated by widespread internal and external deterioration, reduced cross-sections from fire damages, and multiple failed members. Many timber members in the first floor exhibited a very high level of moisture condition (23 to 55%) as a result of high humidity air created by the paper making operations. This paper also showcases a new way of interpreting the evaluation results as straightforward as possible to the customer by creating 3D model-drawings and colored condition mappings.

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Yu, Ling Ling, Jie Jun Wang e Te Huang. "Mechanical Properties of Wood and Timber Bridge Evaluation". Applied Mechanics and Materials 587-589 (luglio 2014): 1381–85. http://dx.doi.org/10.4028/www.scientific.net/amm.587-589.1381.

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Wood possesses material properties that may be significantly different from other materials normally encountered in structural design. It is necessary for the engineer to have a general understanding of the properties and characteristics that affect the strength and performance of wood in bridge applications. This paper discusses the mechanical properties of wood, including elastics properties and strength properties. Timber bridge are often exposed to harsh environment conditions. Over time, this exposure can lead to deterioration. In turn, this deterioration may lead to a loss of structural integrity that is detrimental to the structure and its users. Timber structural elements are susceptible to degradation due to environmental and loading conditions. A variety of inspection techniques can be employed to locate damage and decay in timber members in order to maintain structural performance. Methods of non-destructive techniques for timber bridges are getting more and more important. This paper presents several non-destructive methods to timber bridge structures.

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Sawata, Kei, Takanobu Sasaki, Shuichi Doi e Yasuo Iijima. "Effect of decay on shear performance of dowel-type timber joints". Journal of Wood Science 54, n. 5 (ottobre 2008): 356–61. http://dx.doi.org/10.1007/s10086-008-0963-7.

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37

Xu, Feng, Xiping Wang, Marko Teder e Yunfei Liu. "Acoustic impact testing and waveform analysis for damage detection in glued laminated timber". Holzforschung 71, n. 10 (26 settembre 2017): 801–11. http://dx.doi.org/10.1515/hf-2016-0237.

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AbstractDelamination and decay are common structural defects in old glued laminated timber (glulam) buildings, which, if left undetected, could cause severe structural damage. This paper presents a new damage detection method for glulam inspection based on moment analysis and wavelet transform (WT) of impact acoustic signals. Acoustic signals were collected from a glulam arch section removed from service through impact testing at various locations. The presence and positions of internal defects were preliminarily determined by applying time centroid and frequency centroid of the first moment. Acoustic signals were then decomposed by wavelet packet transform (WPT) and the energy of the sub-bands was calculated as characteristics of the response signals. The sub-bands of 0–375 Hz and 375–750 Hz were identified as the most discriminative features that are associated with decay and delamination and therefore are indicative of the presence of delamination or decay defects. A defect diagnosis algorithm was tested for its ability to identify internal decay and delamination in glulam. The results show that depth of delamination in a glulam member can be determined with reasonable accuracy.

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Hopkin, Anthony A., Sylvia Greifenhagen e Jeff Holland. "Decay, stains, and beetles in ice-storm-damaged forests: A review". Forestry Chronicle 77, n. 4 (1 agosto 2001): 605–11. http://dx.doi.org/10.5558/tfc77605-4.

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A potential long-term threat to ice-damaged forests exists from decays, stains, and wood-boring insects. Damage to large branches or to the main stem can result in heartwood decay, particularly in older or less healthy trees. However, in branch stubs with a diameter of less than 7.5 cm, decay progresses to only a limited degree. Stem damage is not usual after ice storms. However, sunscald is common in sugar maple stands with damaged crowns, sometimes resulting in infection by the sap rot fungus Cerrena unicolor. Fungi of the genera Ophiostoma, Ceratocystis and Ceratocystiopsis (blue stains) can cause significant staining to standing timber in damaged softwood stands; however, these fungi do not cause structural damage. Bark beetles (scolytidae) and wood-borers (buprestidae and cerambycidae), which attack damaged trees in northeastern North America are normally secondary invaders. However, thinning of the canopy from ice damage could cause increased infestation by these insects. Key words: ice storm, decay, fungi, beetle

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Lozano Martínez–Luengas, Alfonso, Manuel Guaita Fernández, David Lorenzo Fouz e Josu Benito Ayúcar. "Investigation about the Decay of the Timber Structure of an Ancient Wine Cellar in La Rioja (Spain) and Sanitation Proposal". Advanced Materials Research 778 (settembre 2013): 976–82. http://dx.doi.org/10.4028/www.scientific.net/amr.778.976.

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In 2011 the collapse of one of the timber pillars that form the structure of the centuries-old warehouse of maceration that the firm "Bodegas Bilbaínas, S. A." helds in the town of Haro (La Rioja), occurred.This paper describes the most significant pathological processes existing in this nave, associated mainly to its wooden components.Then, according to the level of decay, the assessment of the damage in the different elements of the timber frame through nondestructive testing is analyzed, including the constructive and environmental conditions of the cellar.Finally, based on the results obtained, it is proposed the repair process and the design measures necessary to preserve the timber structure, taking into account the heritage significance and the extension of the harm of their components.

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Bobadilha, Gabrielly S., C. Elizabeth Stokes, Grant Kirker, Sheikh Ali Ahmed, Katie M. Ohno e Dercilio Junior Verly Lopes. "Effect of exterior wood coatings on the durability of cross-laminated timber against mold and decay fungi". BioResources 15, n. 4 (18 settembre 2020): 8420–33. http://dx.doi.org/10.15376/biores.15.4.8420-8433.

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Cross-laminated timber (CLT) is increasingly used in building construction worldwide. Durability of CLT against fungal attack has yet to be fully explored. Water intrusion in mass timber can yield dimensional changes and microbial growth. This study evaluated the performance of CLT coated with various water- and solvent-based stains commercially available in the United States. Twelve coatings were tested for moisture excluding effectiveness, water repellency effectiveness, volumetric swelling, and anti-swelling efficiency. Only five coatings repelled water, limiting dimensional changes. A modified version of AWPA E10-16 (2016) was performed to evaluate decay of the coated CLT samples. Weight losses were recorded after 18 weeks’ exposure to the brown-rot decay fungus Gloeophyllum trabeum. In accelerated mold testing, coated CLT samples were grown in chambers containing spores of Aspergillus sp., Rhizopus sp., and Penicillium sp. for 29 d and assessed visually for mold growth. In both tests, coating C (transparent, water-based, alkyd/acrylic resin) performed the best among the tested coatings. Mold growth was completely prevented, and weight loss caused by G. trabeum was approximately 1.33%. Although coating C prevented decay for 18 weeks, coatings are not intended to protect against decay fungi. However, they may offer short-term protection during transport, storage, and construction.

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41

Karppanen, Outi, Martti Venäläinen, Anni M. Harju, Stefan Willför, Suvi Pietarinen, Tapio Laakso e Pirjo Kainulainen. "Knotwood as a window to the indirect measurement of the decay resistance of Scots pine heartwood". Holzforschung 61, n. 5 (1 agosto 2007): 600–604. http://dx.doi.org/10.1515/hf.2007.091.

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Abstract There is wide variation in the extractive content and decay resistance of Scots pine (Pinus sylvestris L.) heartwood. The heartwood is not visible in standing trees and only poorly visible in timber. Therefore, it is difficult to identify extractive-rich trees, and consequently the most decay-resistant heartwood. On the other hand, knots are clearly visible in standing trees and timber. In the present paper we studied the possibility of measuring the decay resistance of Scots pine heartwood indirectly on the basis of the extractive concentration of knotwood. The material investigated consisted of 40 felled trees with a wide between-tree variation for extractive content and decay resistance of their heartwood. The extractive content of knotwood was found to be four- to five-fold higher than that of heartwood. Statistically significant correlations were found between the mass loss of heartwood and the concentrations of total phenolics and stilbenes in knotwood (r=-0.54, P<0.001 and r=-0.40, P=0.011, respectively), and for the concentration of total phenolics (r=0.42, P=0.008) and stilbenes (r=0.39, P=0.012) between heartwood and knotwood. We suggest further development of this technique in the context of rapid industrial screening of durable pine heartwood.

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42

Zhang, Jicheng, Yong Li, Yongshui Huang, Jinwei Jiang e Siu-Chun Ho. "A Feasibility Study on Timber Moisture Monitoring Using Piezoceramic Transducer-Enabled Active Sensing". Sensors 18, n. 9 (14 settembre 2018): 3100. http://dx.doi.org/10.3390/s18093100.

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In recent years, the piezoceramic transducer-enabled active sensing technique has been extensively applied to structural damage detection and health monitoring, in civil engineering. Being abundant and renewable, timber has been widely used as a building material in many countries. However, one of the more challenging applications of timber, in construction, is the potential damage caused by moisture. Increased moisture may cause easier warping of timber components and encourage corrosion of integrated metal members, on top of potentially causing rot and decay. However, despite numerous efforts to inspect and monitor the moisture content of timber, there lacks a method that can provide truly real time, quantitative, and non-invasive measurement of timber moisture. Thus, the research presented in this paper investigated the feasibility of moisture-content monitoring using an active sensing approach, as enabled by a pair of the Lead Zirconate Titanate (PZT) transducers bonded on the surface of a timber specimen. Using a pair of transducers in an active sensing scheme, one patch generated a designed stress wave, while another patch received the signal. While the active sensing was active, the moisture content of the timber specimen was gradually increased from 0% to 60% with 10% increments. The material properties of the timber correspondingly changed under varying timber moisture content, resulting in a measurable differential in stress wave attenuation rates among the different specimens used. The experimental results indicated that the received signal energy and the moisture content of the timber specimens show a parabolic relationship. Finally, the feasibility and reliability of the presented method, for monitoring timber moisture content, are discussed.

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Eleuterio, Ana Alice, Maria Aparecida de Jesus e Francis E. Putz. "Stem Decay in Live Trees: Heartwood Hollows and Termites in Five Timber Species in Eastern Amazonia". Forests 11, n. 10 (13 ottobre 2020): 1087. http://dx.doi.org/10.3390/f11101087.

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Research Highlights: Tree size and wood characteristics influenced the susceptibility of five Amazonian timber tree species to heartwood decay and colonization by termites. Termites occurred in the heartwoods of 43% of the trees, with Coptotermes testaceus the most abundant species. Background and Objectives: Hollows and rotten cores in the stems of living trees have ecological and economic impacts in forests managed for timber. The decision on whether to cut or maintain hollow trees in such forests must account for the susceptibility of different tree species to decay. We investigated tree and wood characteristics of living trees of five commercial timber species in the eastern Amazon that influenced the likelihood of heartwood decay and the occurrence of termite nests inside the rotten cores. Materials and Methods: We used Pearson’s correlations and one-way analysis of variance (ANOVA) to explore relationships among tree basal area and hollow area. We used principal components analysis (PCA) to analyze the variation of wood anatomical traits, followed by a linear regression to explore the relationships between PCA scores, and heartwood hollow area. We used a logistic model to investigate if the probability the occurrence of colonies of C. testaceus inside tree cores varied with tree and species characteristics. Results: Heartwood hollow areas increased with stem basal area. Larger hollows were more likely to occur in species with higher vessel and ray densities, and smaller diameter vessels. Termites occurred in the hollows of 43% of the trees sampled, with C. testaceus the most common (76%). The probability of encountering termite nests of C. testaceus varied among tree species and was positively related to wood density. Conclusions: This study shows that given the increased likelihood of stem hollows and rotten cores in large trees, tree selection criteria in managed tropical forests should include maximum cutting sizes that vary with the susceptibility of different tree species to stem decay.

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Vössing, Konrad J., e Ernst Niederleithinger. "Nondestructive assessment and imaging methods for internal inspection of timber. A review." Holzforschung 72, n. 6 (27 giugno 2018): 467–76. http://dx.doi.org/10.1515/hf-2017-0122.

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AbstractThis paper reviews state-of-the-art in nondestructive testing (NDT) and semidestructive testing (SDT) methods applicable for imaging the condition of structural timber. Both NDT and SDT imaging reveal defects, damages, and decay, while the extent of wood decay can also be quantified. Combined with an appropriate data interpretation concerning the internal defects, the mechanical properties of the material can also be assessed. The possibilities and limitations of the most relevant individual NDT and SDT methods, also in combination with each other, are outlined and compared. To facilitate comparison, many observations are reported based on the same test specimen.

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Schmid, Joachim, e Andrea Frangi. "Structural Timber In Compartment Fires – The Timber Charring and Heat Storage Model". Open Engineering 11, n. 1 (1 gennaio 2021): 435–52. http://dx.doi.org/10.1515/eng-2021-0043.

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Abstract The influence of exposed timber surfaces on compartment fires has been well documented in various studies in recent decades. Yet available design concepts still typically neglect the influence of an additional fire load from linear structural timber elements such as beams and columns. As rules for large shares of exposed timber surfaces, e.g. by panels, are rare, authorities and fire safety engineers demand often mock-up compartment fire experiments to estimate the fire safety of a particular design. Such experiments, however, are costly, time consuming, and give limited insights into the potential fire scenarios and may fail to represent properly the fundamental effects arising from exposed structural timber elements in a fire. An approach to overcome these existing limitations is presented, which is able to estimate the contributions from structural timber to a fire from its fully developed- and decay phase until burnout. The model input is developed from an experimental campaign where the relevant effects of fire exposed structural timber could be isolated and measured. It was found that the energy stored in the char layer is a key characteristic for describing the fire dynamics of compartment fires with exposed structural timber. Consequently, the proposed approach describes a framework for the Timber Charring and Heat storage, the TiCHS-model. The validation of the model is shown in this paper by means of existing compartment experiments. A current limitation is the bond line integrity of the fire exposed components as the combustion characteristics of failed char pieces on the floor are currently unknown.

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Nakai, Kazushi, e Tsuyoshi Yoshimura. "African blackwood (Dalbergia melanoxylon) and other local Tanzanian tree species’ biological performance against subterranean termites and wood decay fungi". BioResources 15, n. 2 (13 marzo 2020): 2994–3005. http://dx.doi.org/10.15376/biores.15.2.2994-3005.

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African blackwood (Dalbergia melanoxylon) is known as an indispensable material for the production of musical instruments, e.g., clarinets, oboes, and piccolos. The authors focused on the biological performance of African blackwood and other local Tanzanian species in order to collect preliminary data for developing further uses for these local timbers. Five local species, including African blackwood, were exposed to both subterranean termites (Coptotermes formosanus) and two wood decay fungi (White rot fungus (Trametes versicolor) and Brown rot fungus (Fomitopsis palustris)) according to Japanese standard test methods. African blackwood heartwood had high durability against both termite and fungal attacks, as well as the highest air-dried density of all test species. Some species also indicated a higher durability, even though they had a lower density than African blackwood heartwood. The authors showed the importance of heartwood extractives in terms of biological performance for the local Tanzanian timbers. The authors findings suggested that African blackwood heartwood was clearly useful as a high-durability material in addition to current major applications. The potential of the other local species was also suggested in terms of further timber utilization. These results presented fundamental information about sustainable forest management based on the effective utilization of local timbers.

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Richards, Jenny, e Peter Brimblecombe. "Moisture as a Driver of Long-Term Threats to Timber Heritage—Part I: Changing Heritage Climatology". Heritage 5, n. 3 (29 luglio 2022): 1929–46. http://dx.doi.org/10.3390/heritage5030100.

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Timber is widely used in the construction of buildings on a global scale, but it is sensitive to degradation. Moisture notably poses a risk to timber decay, and this is likely to change significantly during the 21st century if a high emission scenario occurs. Global HadGEM3 model output was used to map projected changes in relative humidity range, seasonality of relative humidity, time of wetness, wind-driven rain, salt transitions and potential for fungal attack (Scheffer Index). In the Congo Basin, Great Plains (USA) and Scandinavia, humidity ranges are likely to increase along with seasonal change. In many parts of the tropics, time of wetness is likely to decrease by the end of the century. Increases in days of wind-driven rain are projected for western Russia, eastern Europe, Alaska, western Canada and Southern Brazil and Paraguay. Drylands have historically had a low salt risk, but this is projected to increase. In the future, a broad extension of fungal risk along the Himalayas and into central China seems likely, driven as much by temperature as rainfall. The picture presented suggests a slightly less humid heritage climate, which will redistribute the risks to heritage. Mapping global pressures of timber decay could help policymakers and practitioners identify geographically disparate regions that face similar pressures.

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Miina, Jari, Hanna Muttilainen, Juha Vornanen e Henri Vanhanen. "Supply Chain Actors’ Perspectives Concerning the Cultivation of Specialty Wood-Decay Mushrooms in Finland". Forests 14, n. 1 (11 gennaio 2023): 134. http://dx.doi.org/10.3390/f14010134.

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The objective of this paper was to understand the perspectives of multiple stakeholders on the adoption of specialty wood-decay mushroom cultivation on stumps in connection with timber harvesting in Finland. The perspectives of supply chain actors, i.e., forest owners, forest harvesting entrepreneurs, forest professionals, and natural product entrepreneurs, were assessed using web-based questionnaires. Forest professionals (34%) were most interested in specialty mushroom cultivation in co-operation with companies selling cultures or buying mushrooms, whereas about one-fourth of the forest owners (23%) indicated that interest. Forest owners were willing to do the cultivation by themselves and to lease their forests for mushroom cultivation. Compared to household users, forest owners who had commercialised the non-timber forest products (NTFPs) of their forests or were willing to sell licences for NTFP picking and gathering permits were more interested in mushroom cultivation. Additionally, background information on forest owners, such as part-time forestry entrepreneurship, younger age, male gender, and higher education, significantly increased the odds of indicating interest in participating in the supply chain. One-fourth of the harvesting entrepreneurs (25%) indicated an interest in marketing and providing specialty mushroom cultivation services to forest owners in timber harvesting. Specialty mushrooms were already used by 26% of natural product entrepreneurs, and 40% indicated that specialty mushrooms could be used in the future. The shortage of information on, for example, cultivation success, yield, and costs, as well as profitability analyses, was acknowledged by all supply chain actors as the most serious barrier inhibiting their partnership in the production and utilisation of specialty mushrooms.

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Musah, Munkaila, Javier Hernandez Diaz, Abiodun Oluseun Alawode, Tom Gallagher, Maria Soledad Peresin, Dana Mitchell, Mathew Smidt e Brian Via. "Field Assessment of Downed Timber Strength Deterioration Rate and Wood Quality Using Acoustic Technologies". Forests 13, n. 5 (12 maggio 2022): 752. http://dx.doi.org/10.3390/f13050752.

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Hurricane and tornado events cause significant damage to high-value timber in the United States each year. Forest managers and landowners are keenly interested in finding solutions to salvage and repurpose these downed timbers before they cause pest infestations and fire outbreaks, completely losing their value or increasing processing costs. To better understand the wood quality of the downed timber, we used acoustic waves techniques as a nondestructive testing approach to assess the wood degradation rate of downed trees and determine the extent of fracture and voids in the damaged regions. We periodically monitored the acoustic velocity of the downed trees for 12 consecutive months using a time of flight (TOF) acoustic method. Acoustic measurements were conducted using three different techniques—longitudinal, transverse, and off-set methods. Wood density, age, and the diameter at breast height (dbh) class measurement for southern timber (chip-n-saw for dbh 8″–11″ and sawtimber with dbh 12″ and up) were used as the predictive parameters of the downed trees. The results indicated positive relationships between dbh class, stand age, and acoustic velocity measurement (R2 > 65%). The TOF acoustic velocity was indicated to potentially separate higher-stiffness timber from lower-stiffness timber in a hurricane event for structural or non-structural applications. The regression coefficient from the repeated measurements indicated that both age and diameter class strongly impacted the acoustic properties of the downed trees (p-value ≤ 0.001). The sawtimber dbh class recorded a higher acoustic velocity compared to the chip-n-saw type. Fracture, voids, and massive decay in downed trees were detected beyond the visible inspection, features that often are identified by loggers in lower quality wood; however, TOF showed a weak response in picking up incremental deterioration due to changes in specific environmental factors that affected acoustic readings. This study showed that acoustic wave methods could potentially be used as a field evaluation tool for assessing the quality of downed trees.

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Toda, Masahiko, Mitsunori Mori, Yoshinori Ohashi e Takuro Hirai. "Effects of Wood Decay on the Shear Performance of Nailed Timber Joint". Mokuzai Gakkaishi 56, n. 1 (2010): 41–47. http://dx.doi.org/10.2488/jwrs.56.41.

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