Wood durability in terrestrial and aquatic environments – A review of biotic and abiotic influence factors

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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.

Section: Modelling Materials Resistance In Soil Contactmentioning

confidence: 99%

Modelling the Material Resistance of Wood—Part 3: Relative Resistance in above- and in-Ground Situations—Results of a Global Survey

Brischke

Alfredsen

Humar

et al. 2021

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“…In the general service-life design framework, the resulting exposure dose is then combined with a material-inherent resistance dose to account for the protective properties (natural, modified, or treated) and moisture dynamics (wetting ability) of the specific material [20,21]. For terrestrial environments (use-class 4), the wood moisture content is influenced by the soil and can often be assumed to remain permanently damp [35,36].…”

Section: In-ground Contactmentioning

confidence: 99%

Evaluation of Moisture and Decay Models for a New Design Framework for Decay Prediction of Wood

Niklewski

Niekerk

Brischke

et al. 2021

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Performance-based, service-life design of wood has been the focus of much research in recent decades. Previous works have been synthesized in various factorized design frameworks presented in the form of technical reports. Factorization does not consider the non-linear dependency between decay-influencing effects, such as between detail design and climate variables. The CLICKdesign project is a joint European effort targeting digital, performance-based specification for service-life design (SLD) of wood. This study evaluates the feasibility of using a semi-empirical moisture model (SMM) as a basis for a digital SLD framework. The performance of the SMM is assessed by comparison against a finite element model (FEM). In addition, two different wood decay models (a logistic, LM, and simplified logistic model (SLM)) are compared. While discrepancies between the SMM and FEM were detected particularly at high wood moisture content, the overall performance of the SMM was deemed sufficient for the application. The main source of uncertainty instead stems from the choice of wood decay model. Based on the results, a new method based on pre-calculated time series, empirical equations, and interpolation is proposed for predicting the service life of wood. The method is fast and simple yet able to deal with non-linear effects between weather variables and the design of details. As such, it can easily be implemented as part of a digital design guideline to provide decision support for architects and engineers, with less uncertainty than existing factorized guidelines.

“…For outdoor use, wood is exposed to many abiotic and biotic factors, such as weather conditions and biodegradation, which negatively affect the wood material's physical, biological, chemical, and mechanical properties [12].…”

Section: Exterior Woodmentioning

confidence: 99%

“…In the last years, several studies have been conducted to evaluate the impact of weathering in thermally modified wood. Studies on the exposure of wood to natural weathering conditions (urban environments) [5,12,42,[51][52][53][54][55][56] or artificial exposure through the use of climatic chambers (UV radiation, temperature, and humidity) [57][58][59][60][61][62] were conducted.…”

Section: Weatheringmentioning

confidence: 99%

Thermally Modified Wood Exposed to Different Weathering Conditions: A Review

Godinho

Araújo

Quilhó

et al. 2021

Outdoor wood applications are exposed to several different biotic and abiotic factors, and for that reason, they require protection to increase their service life. Several technologies of wood protection are already commercialized. One of these technologies is thermal modification, which refers to the structural, mechanical, and chemical transformations occurring in the lignocellulosic material when gradually heated up to specific temperature ranges. In the past few years, several researchers have undertaken weathering resistance evaluations on different wood species. Some cases have considered natural exposure in different countries with different climatic conditions, while others focused on artificial exposure under UV and xenon radiation tests. Most works evaluated the weathering effects on the chemical, mechanical and physical, and anatomical shifts compared to the original characteristics of the material. This review has established a considerable lack of studies in the bibliography focusing on abiotic factors, such as the industrial and maritime environment, or even isolated climatic factors such as salt spray (simulating maritime environments) or pollutant gases (simulating industrial environments). This lack of information can be an opportunity for future work. It could help to understand if thermally modified wood is or is not sensitive to pollutant gases or salinity, or to a combination of both. By knowing the degradation mechanisms caused by these factors, it will be possible to study other forms of protection.