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•A custom-built device was used to measure fluorescence from Scots pine heartwood.•Heartwood fluorescence intensity and stilbene content had a quantitative association.•Fluorescence ...measurements could be performed on green and dried heartwood.•Stilbene content is a promising variable for predicting heartwood decay resistance.•The method has potential to be utilized in timber grading and tree breeding programs.
Decay resistance is an important property of heartwood timber. The decay resistance of Scots pine heartwood correlates with its stilbene content, but the determination of both requires laborious and destructive analyses. To aid in the determination of these important properties, we investigated the feasibility of an optical method based on the intensity of UV-excited fluorescence for the non-destructive measurement of heartwood stilbene content and decay resistance. Fluorescence measurements carried out on samples from 58 trees showed a high correlation (r = 0.79, p < 0.000) between fluorescence intensity and stilbene content. The intensities measured from green and dried samples were highly correlated. The correlation between the fluorescence intensity and mass loss due to the brown rot fungus Coniophora puteana (r = -0.64, p < 0.000) was lower than the correlation between the stilbene content and mass loss (r = -0.78, p < 0.000). Nonetheless, the method showed promise in separating the low and high mass loss samples from the average heartwood material. The fluorescence-based method may be utilized in timber grading and tree breeding, and due to the strong correlation between green and dry measurements, it may be applied at any stage of the processing chain.
This study investigated possibilities to predict the presence of internal checks in thermally modified Norway spruce timber after 2.5 years of weathering based on the initial properties of the ...boards. Machine-learning classification enabled sorting the input parameters based on their relative importance for accurate predictions. The parameters of thermally modified timber with the highest relative importance were annual ring width followed by initial moisture content, density and dynamic stiffness. Whereas after kiln drying these were, density, annual ring width, initial moisture content and acoustic velocity. The results showed that predictions are possible, and an accuracy of 67% was achieved by using annual ring width combined with density and initial moisture content, or acoustic velocity that can be determined after either kiln drying or thermal treatment.
•Surface checking and mechanical properties of weathered Thermally modified timber (TMT) were predicted.•Board’s dynamic stiffness is the most crucial predictor variable.•Initial moisture content is ...an important predictor of TMT’s bending strength.•Models failed to accurately predict the degree of surface checking in weathered TMT.•Decision tree and ANFIS outperform regression models when predicting TMT’s bending properties.
Machine learning (ML)-based models, decision tree and ANFIS, were used to predict the degree of surface checking and bending properties of 30-month weathered thermally modified timber. The results showed that the investigated initial board properties did not allow accurate predictions of surface checks. ML regression and clustering analysis confirmed important variables for accurate predictions of bending properties were dynamic stiffness, acoustic velocity, density and lowest local bending modulus. ML models performed better than conventional regression models used for timber grading, and a prediction accuracy of 80–90% for bending stiffness and 50–70% for bending strength could be achieved.
•Currently, Populus spp. timber is not included in Spanish visual grading standard.•Qualifying efficiency of UNE-56544:1997 applied in this timber is not appropriate.•ME-1 visual grade does not ...comply to the minimum values established in EN-338.•Supervised Machine Learning algorithms use improves this qualifying process.•Visual defects, sawing systems and non-destructive variables were better predictors than UNE-56544.
The efficiency of visual grading standards applied to structural timber is often inappropriate, and timber properties are either under or over-graded. Although not included in the current UNE 56544 visual grading standard, machine learning algorithms represent a promising alternative to grade structural timber. The general aim of this research was to compare the performance of machine learning algorithms based on visual defects, non-destructive techniques and sawing systems (“cut type”) with UNE 56544:1997 visual grading in order to predict the qualifying efficiency of Populus x euramericana I-214 structural timber. Visual evaluation, ultrasound and vibrational non-destructive testing, and sawing systems register (radial, tangential and mixed) were applied to characterize 945 beams. In addition, in order to retrieve actual physical-mechanical values, density and static bending destructive testing (EN-408:2011 + A1:2012) was also carried out. Several machine learning algorithms were then used to grade the beams, and their predictive accuracy was compared with that of visual grading. To do so, three scenarios were considered: a first scenario in which only visual variables were used; a second scenario in which “cut type” variables were also included; and a third scenario in which additional non-destructive variables were considered. Results showed a poor level of performance of UNE 56544:1997, with an apparent mismatch between the strength values assigned for each visual grade (established by the EN 338 standard) and the actual values. On the opposite, all algorithms performed better than visual grading and may thus be deemed as promising timber strength grading tools.
Key message
The potential of European National Forest Inventories to harmonise stem quality estimation in European forests was identified despite considerable differences in existing national ...approaches.
Context
Knowledge on stem quality and assortments structure in European forests is highly important for policy makers and the timber industry and also for carbon life cycle analysis due to the fact that different timber products have different end use and thus store carbon for different time periods.
Aims
The study aim was to evaluate the potential of European National Forest Inventories (NFI) to objectively report on the stem quality in European forests in a harmonised manner.
Methods
A comprehensive questionnaire was conducted as the first important step to evaluate the current status of stem quality assessment and assess the existing level of harmonisation.
Results
Direct stem quality assessment or classification is used in 19 out of 28 European NFIs. Only eight countries provide timber assortment estimates from their NFIs. In addition, different sampling strategies for stem quality assessment are used among NFIs. Tree parameters relevant for stem quality assessment on standing trees were identified for the purpose of harmonisation. Several methods towards harmonisation between European NFIs for the purpose of reporting on stem quality of European forests were suggested.
Conclusion
Current European NFIs are not capable of reporting the stem quality of European forests in a harmonised manner at this stage and considerable efforts will need to be taken before the harmonised stem quality estimation can be prepared. However, the inquiry also revealed that there is a potential to develop the harmonised estimations in future.
Wood stabilization and functionalization is a hot topic towards increasing the use of wood in buildings. Building construction and materials account for around 11% of the global CO2 emissions, thus ...there is increasing interest in using wood to replace concrete, steel, and aluminium. However, the perceived quality of wood in service decreases quickly in comparison with non-biodegradable alternatives, so aging must be delayed as much as possible through stabilization and functionalization. The question addressed in this paper is how to measure the perceived quality of wood products in service. The concept of wood quality is difficult to define, as it depends on a combination of factors such as customer satisfaction, wood fibre characteristics, products, applications, and so on. This paper proposes a definition of timber quality based on market price. By knowing the market value of a potential range of wood products, the proposed method calculates the loss of value due to developing defects caused by aging. Overall, the proposed methodology allows converting the subjective concept of aging into an objective $ value. A numeric example is presented based on the New Zealand timber grading rules. The results showed that 5.1 m by 150 mm by 50 mm softwood timber can lose up to 61% of its value as appearance grade if a single aging defect develops beyond the maximum allowed size.
The paper presents the results of experimental tests and the process by which a batch of spruce timber elements is sorted in a strength class with reliability.
Timber buildings are experiencing a rapid diffusion due to their good performance and their sustainability; however, some steps of structural timber production process, such as drying, are ...energy-intensive and environmentally impactful, and many wood species are also affected by low yield. Therefore, it would be important to determine the quality of the green material, that is, in wet condition, before undergoing the most impactful and expensive production steps. This paper describes a research aimed at quantifying the variation of the dynamic modulus of elasticity MoEdyn, which is commonly used for structural timber mechanical grading, from wet to dry condition in Sardinian maritime pine boards to be used for the production of laminated timber, and to examine the relationship between wet and dry MoEdyn. The MoEdyn was determined from measurements of the velocity of sonic waves propagating through the boards. The results show that the dry MoEdyn can be estimated starting from boards sonic testing in the wet condition, so providing a basis for implementing Sardinian maritime pine pre-grading in order to obtain the reduction of manufacturing costs, the abatement of environmental impact, and the increase of structural grade yield.
Despite the variability and particularities that the timber reveals, the strength class grading system has been developed to meet the need to correlate structural design standards with quality ...standards for timber products. The paper presents the standardised approaches for determining the characteristic values of properties for timber products, with the purpose of classifying the material according to the strength classes system presented in European standards.
Baltic shipping marks on nineteenth-century timber Vandenabeele, Louis; Bertels, Inge; Wouters, Ine
Construction history : journal of the Construction History Group,
01/2016, Letnik:
31, Številka:
2
Journal Article
Recenzirano
Intriguing marks have been recorded on numerous nineteenth-century timber structures throughout Europe. These inscriptions bear witness to an intensive trade that supplied Norwegian and Baltic timber ...– mainly softwood – to most Western European countries. Despite the abundance of archaeological records, the current understanding of these shipping marks is very limited. Consequently, historical surveys and restoration campaigns are not using their potential for a better understanding of historic timbers.
This paper aims at understanding the organisation of the nineteenth-century Baltic timber trade and at investigating the need for marking timber at different stages in this trade. It focuses on deciphering the shipping marks, based on a survey of historic texts, including treatises on forestry, merchants’ guides, trade journals and construction handbooks.
The gathering of this historical knowledge provides the basis for an innovative decoding method, which is illustrated through the deciphering of some of the recently recorded marks. The results of these investigations show that the Baltic shipping marks provide valuable information about the dating, origins and qualities of historic timber, as well as the economic actors involved in its trade. This research paves the way for further on-site investigations and a strengthened international collaboration that could improve and regularise the decoding of these inscriptions.
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