Dazomet (tetrahydro-3,5-dimethyl-2H-1,3,5-thiadiazine-2-thione) is a solid fumigant that breaks down into gaseous methylisothiocyanate (MITC) in the presence of water, a process that can be enhanced by the addition of accelerant chemicals. Experiments to discover the ideal conditions for dazomet decomposition were largely performed at the lab scale or on field-scale full utility poles or sections thereof. A rapid assessment method in wood commodities would improve the ability to assess a wider range of treatments to improve performance. Here, we present a method to test dazomet performance at the mesocosm scale in 102 × 152 mm (4 × 6-inch nominal) lumber. The protocol was trialed using two EPA-registered dazomet formulations to produce MITC under varying moisture conditions using different copper-containing accelerants. The test allowed the assessment of MITC levels at different locations and the full visual inspection of the treatment hole after splitting the block. MITC levels tended to be higher in the wood interior, closer to the treatment holes in test blocks. Below-ground portions also tended to have higher MITC levels at higher-moisture conditions. The method developed reduces the time required to test dazomet formulations and application methods in whole wood and will help improve the development of new dazomet formulations and application methods.

Dowel bearing strength of three cross-laminated timber (CLT) species (Douglas-fir, Norway spruce, spruce pine fir) were periodically assessed through 40 weeks of exposure to two brown rot fungi species (Gloeophyllum trabeum and Rhodonia placenta). Time-dependent regression models were developed to describe the relationship between level of fungal exposure and dowel bearing strength of CLT. Obtained dowel bearing strength values were used to predict the capacity of floor-to-wall CLT connection systems. Predicted strength values were compared with capacity of actual connection systems which were subjected to similar biodeterioration treatments. Significant reductions in the dowel bearing strength of CLT were observed 30 weeks after fungal inoculation. Similar patterns of degradation were observed for both fungi in all three CLT species, but R. placenta was slightly more aggressive than G. trabeum, causing a 16.2 MPa reduction in dowel bearing strength of Douglas-fir after 40 weeks of exposure. Connection capacities estimated using National Design Specification yield models for dowel type fasteners and the dowel bearing strength of fungal-damaged CLT were consistent with observed properties and were within 85% of actual capacity of connections tested, especially in early stages of decay.

Chromated copper arsenate (CCA) is a preservative treatment that enhances the biodegradation resistance of wood, essential for prolonging the service life of exterior infrastructure. However, the susceptibility of CCAtreated wood to smouldering combustion presents a significant challenge, as the metals present in the CCA catalyze the smouldering. In this work, we examined the oxidative behaviour of char produced from CCA-treated wood through dynamic thermogravimetric analysis. There was a gradual decrease in the catalytic activity of the CCA as temperature increased, particularly above 400 degrees C. At this stage, lignin undergoes secondary pyrolysis, and thermal decomposition of CCA complexes occurs. The thermal decomposition of CCA-treated wood at temperatures above 650 degrees C was similar to that of untreated wood, indicating the possible deactivation of the CCA. The agglomeration of species containing Cu or Cr above 650 degrees C might be responsible for the deactivation. This process is influenced by simultaneous lignin pyrolysis and decomposition of CCA complexes, which are also likely contributors to the loss of CCA's catalytic activity. This research introduced a novel experimental approach to assess the catalytic effects of CCA on char oxidation at elevated temperatures, offering valuable insights into CCA deactivation and its implications for fire safety. It also contributes to the development of potential modifications to CCA formulations aimed to reduce smouldering in wildfire-prone regions.

Biological durability remains an understudied area of mass timber construction, despite expert warnings on potential moisture and decay issues that may affect building performance. In an effort to bridge the knowledge gap, this article presents experimental data on the performance of fungal-decayed cross laminated timber (CLT) connection assemblies. A total of 560 connection assemblies were made using select CLT species from major global markets. These were mechanically tested following inoculation by two brown rot fungi for a total period of 78 weeks, with the connections periodically harvested after 10, 20, 30, 40, 52, and 78 weeks. The data from the mechanical tests, which included cyclic evaluation using an abbreviated CUREE loading protocol and dowel bearing strength tests performed in accordance with ASTM D5764, are submitted in this repository. The repository also contains information on mass changes to connection assemblies as decay progressed and SAWS model parameters that were calibrated using the raw data generated from the universal testing machine (UTM) during cyclic tests of the connection assemblies. This work is fundamental for accurate assessment of fungal deterioration in mass timber buildings and the data submitted herein could be used by researchers and scientists to model behavior of connections in mass timber buildings, especially in humid and damp regions with high chances of biodeterioration.

The effect of biodeterioration on the structural connection performance of timber for conventional framing and mass timber has been investigated recently, but there is a need for additional data as well as for the development of analytical models to utilize these data. An empirical material model (seismic analysis of wood frame shear walls) was fitted to cyclic connection test data of four species of cross-laminated timber at different levels of biodeterioration by two brown-rot fungi. These model inputs were then analyzed to account for trends between wood species and fungal species. Weak trends were most prominent for initial stiffness, intercept load, and displacement at peak force. Correlations were poor with postyield and postpeak stiffness modifiers. These relationships were consistent both as a function of time and as a function of mass loss, but additional data are needed to more accurately predict the effects. The limited relationships likely reflect the variations in fungal decay across the test members.

Abstract Understanding the durability of emerging plantation hardwood resources is important for optimising their production and use. This study compared timber density, extractives content and decay resistance in 12–13-year-old plantation and native forest regrowth Gympie messmate (Eucalyptus cloeziana) trees. Density increased from pith to bark for both plantation and native forest trees. Inner heartwood density of the plantation timber was significantly lower than that of the native forest regrowth timber. While the total extractives content of the outer heartwood was comparable in the plantation and native forest regrowth trees, the inner heartwood of the latter contained significantly greater extractives levels. Laboratory decay tests showed that all heartwood zones of plantation and native forest regrowth Gympie messmate were resistant to decay by the white rot Pycnoporus coccineus. The inner heartwood of the plantation timber was, however, susceptible to decay by the brown rot Fomitopsis ostreiformis. The results illustrate the potential variations in wood quality parameters to be considered when moving from native forest to plantation resources that are harvested at a younger age and managed for more rapid wood production.

Superhydrophobic surfaces have a number of potential applications including separating oil from water for pollution abatement. Wood is an excellent matrix for creating these surfaces because its interactive chemistry and intricate cellular matrix provides a large, reactive surface area for fabrication. The challenge to using wood is identifying simple pathways for in-situ synthesis. Na3(Cu2(CO3)3OH)center dot 4H2O was synthesized in-situ on deligni-fied balsa wood reacting copper chloride and sodium hydroxide in the presence of phenol formaldehyde (PF) resin, and then using stearic acid (STA) to modify this surface to be superhydrophobic. The modified wood surface was covered with Na3(Cu2(CO3)3OH)center dot 4H2O tetrahedral particles, and had a surface free energy of 8.0 J/ m2, which was about 90 % lower than that natural balsa wood. The modified wood had excellent absorption and filtration capabilities for various oils and was able to absorb 2.1-4.8 times its weight in oil, with oil absorption reaching a maximum of 5.2 g/g for chloroform. The modified wood could be regenerated and reused up to 14 times, and the still retained a separation efficiency of 90 % for a dichloromethane:water mixture within 11 cycles. The results suggest that wood-based superhydrophobic surfaces could represent a more environmentally benign material for remediating spills.

Abstract The biological deterioration of archaeological wood under oxygen-limited conditions varies due to the limited activities of microorganisms. It is essential to expand the knowledge of the degradation types and the status of archaeological monuments for selecting the proper consolidates. The physical, chemical, and anatomical properties of approximately 600–650 year old archaeological oak collected from an archaeological site in Iasi-Romania were analysed to assess the quality and to identify the degradation types. The results were compared with similar tests on recently-cut oak. X-ray photoelectron spectroscopy (XPS) revealed the presence of more lignin-related peaks in the archaeological oak, which likely reflected the degradation of the wood carbohydrates as evidenced by the decreased oxygen-to-carbon ratio C ox/C non-ox. The differences in cellulose crystallinity were not significant suggesting that any cellulose degradation occurred in the amorphous regions. This was also reflected in the dynamic water vapor sorption analysis where the differences in sorption isotherms and hysteresis of archaeological and recently-cut oaks were marginal. Microscopic analysis of the oak cells illustrated bacterial degradation patterns, while the field emission scanning electron microscopy (FESEM) showed the presence of erosion bacteria in the archaeological oak collected from the site with low oxygen conditions.

Cryptomeria fortunei has been widely planted in many cities in southern China. Eventually some of this material may be utilized for timber, but there are relatively few studies of durability of this resource. There is also some question as to whether Cryptomeria fortunei is a synonym for Cryptomeria japonica or Japanese cedar (Sugi). Evaluating the durability of the Chinese resource will help ensure that the decay resistance of this urban plantation resource is properly categorized. The decay resistance of Cryptomeria fortunei wood was assessed in soil block and agar block tests against Trametes versicolor, Gloeophyllum trabeum and Rhodonia placenta. Hot water and ethanol extractive contents of the heartwood were determined on sections from various distances above ground and then FTIR spectroscopy was used to characterize the wood before and after fungal exposure. Weight losses in sapwood were consistent with the minimal decay resistance of this portion of the wood. Inner and outer heartwood weight losses were more variable suggesting that the heartwood of this species would be considered to be only moderately durable. Extractives were weakly correlated with decay resistance. FTIR results were more variable, although they suggested heavier attack of lignin components by the brown rot fungi. The results suggest that Cryptomeria fortunei would need to be protected from the weather unless supplemental preservative treatments were applied.

Short rotation plantation forests in Tasmania, Australia, are dominated by Eucalyptus nitens (common name: shining gum). These forests were primarily planted to provide material for pulp and paper production, but the timber is increasingly sought after for higher value and more enduring applications. Plantation E. nitens has a high proportion of low-durability heartwood that resists penetration by conventional fluid preservatives. This limits its use to indoor applications. One approach to overcoming the refractory nature of E. nitens is to modify the treatment fluid. We investigated the use of supercritical carbon dioxide to deliver biocides deep into the wood. Timbers varying in thickness from 19 to 35 mm and 900-mm long were treated with a multicomponent biocide under supercritical conditions in a commercial facility in Denmark. The result-ing timber was cut into zones inward from the surface. Wood from these zones was grounded and extracted for HPLC analysis for tebuconazole and propiconazole. Preservative was detected in the inner portion of every sample examined, indicating that the process resulted in treatment throughout the boards, with concentrations meeting and on average exceeding the targeted amounts.

This paper describes fire safety experiments on Australian native timber samples with a special focus on their use in bushfire-prone areas. Nine species were assessed through testing in a cone calorimeter, thermogravimetric analysis and differential scanning calorimetry (DSC). The effects of density, moisture content and chemical extractives content were evaluated. Marked differences in ignition times were found, possibly due to variations in density across species, as well as the chemical extractives content. Analysis of the heat flow through DSC indicated that the type of extractives can influence the fire safety performance and that this aspect of wood properties merits further study. One additional species was identified as a suitable candidate for bushfire-resisting species in the Australian bushfire context.

As mass timber buildings continue to gain widespread acceptance in North America, there is the need to address concerns, which might impact the performance of these novel buildings. Moisture intrusion poses significant levels of risks to mass timber elements and has been associated with durability concerns and possible reduction in performance of structural elements and connection systems. While it is recommended to employ design approaches that eliminate moisture accumulation in buildings, the possibility of elements getting wet during, or post construction remains reasonably high. Hence, it is important to re-dry elements once wet to avoid these issues. Additionally, connections constitute an important part of the lateral force resisting system and must be well studied for optimum performance under all conditions. This study therefore characterized the wetting and redrying performance of Cross Laminated Timber (CLT) angle bracket connections made from four CLT species. The effects of three different drying methods on the load carrying capacity, stiffness, and energy dissipating capacity of the connections were studied. Load carrying capacity of the connections was barely affected, but aggressive drying induced brittleness in some connections, and consequently impacted energy dissipating capacity. Physical observation of the connection assemblies also showed varying degrees of damage, which can be attributed to accumulation of drying stresses depending on the drying method employed.

In wood, longitudinal fluid flow is several orders of magnitude greater than in radial or tangential directions. Incising of difficult-to-treat (i.e. refractory) wood species is a critical step in achieving adequate preservative penetration. Incising, as broadly defined, involves creating holes, incisions or fluid pathways to varying depths into the timber to increase longitudinal fluid flow and penetration into the wood. Incising has been used globally with early development occurring in the U.S., Canada, U.K. and Germany. It has been most heavily adopted in North America where it is required for treatment of thin sapwood lumber species in both the Canadian and U.S. treatment and engineering design standards. Incising can be either physical or biological. Physical incising uses teeth, knives, drills, needles, lasers, or high-pressure water jets to create pathways in the wood to the depth of the desired preservative treatment in a pattern that ensures uniform treatment. Biological incising uses bacteria or fungi to increase permeability. This review outlines the development, processes, applications and effects of incising technology. It specifically discusses their effects on treatability and strength properties, and reviews recent developments for modeling incising-related strength effects.