Alkaline copper quat (ACQ) is an established wood preservative that is formulated with solubilized copper in amine solvent. This article describes three separate trials in Australia that investigated whether substituting soluble copper with micronized copper affects performance. ACQ and micronized copper quat (MCQ) performed similarly in Pinus radiata against four brown-rot fungi in a soil-block bioassay, while MCQ performed slightly better against two white-rot fungi in Eucalyptus delegatensis. A 2.3-year in-ground stake trial in the wet tropics at Innisfail also found that ACQ and MCQ performed comparably in P. radiata and Corymbia maculata. This was a severe test site with attack caused by soft-rot fungi, white-rot fungi, and termites. An H3 (outside, aboveground) field test against termites in Darwin showed that ACQ- or MCQ-treated P. radiata and C. maculata performed similarly against Coptotermes acinaciformis and Mastotermes darwiniensis. These trials demonstrated that MCQ performs comparably to ACQ under the test conditions used.
Borate penetration relies on diffusion when borate and glycol-borate preservatives are applied to the surface of wood. This study evaluated the extent of borate penetration in framing lumber as a function of preservative formulation, wood moisture content, and diffusion time after treatment. In Phase I of the study, end-matched specimens were conditioned to target average moisture contents of 15, 25, or 35 percent, briefly immersed in borate formulations, and then placed into wooden frames to minimize air exchange during diffusion. Penetration in these specimens was generally less than 5 mm (or 35% of the cross section) regardless of treatment solution, target moisture content at time of treatment, or diffusion period (2, 4, or 8 wk). Assay of boron concentrations after 8 weeks of diffusion also indicated that the boron was concentrated in the outer 5 mm of the wood. Diffusion appeared to have been limited by the relatively rapid drying of the specimens, even with the restricted air movement within the wooden frames. In Phase II of the study, specimens were conditioned to a target average moisture content of 20 percent prior to dip immersion and then placed in a room that maintained an equilibrium moisture content of 19 to 21 percent. Penetration in these specimens was assessed after 6, 13, and 26 weeks of diffusion. After 6 weeks of diffusion, average boron penetration exceeded 5 mm, and after 26 weeks of diffusion, penetration exceeded 11 mm, or over 70 percent of the cross section. Little difference in diffusion was observed between the types of borate formulations evaluated in either phase of this study. The results of this study indicate that rapid drying conditions may limit penetration of boron from spray applications; however, in situations where high humidity is maintained in a structure, substantial diffusion is possible.
The amounts of treated wood present at a wood recycling center in western Oregon were surveyed over a 10-year period. Treated wood was found at 106 of 112 inspections, but the levels never exceeded 2 percent of the volume present. The amount of treated wood averaged 0.15 percent of the total volume over the 10 years. These values were considerably lower than those found in surveys in Virginia and Florida, reflecting a lower overall use of treated wood and, with respect to Florida, a lower risk of decay in Oregon. The results indicate that treated wood is a minor component in the recycling stream studied and does not pose a risk to those using the material.
The purpose of this study was to investigate emissions during storage of solid wood fuels by measuring both the emission of monoterpenes and the formation of aldehydes during storage of undried sawdust, dried sawdust, and pellets. Sawdust is commonly stored up to several months at pellet plants. Pellets are stored due to seasonal demand variation and wood fuel trade. Freshly sawn sawdust from Scots pine (Pinus sylvestris) was dried and pelleted. The fuel was stored in a controlled laboratory setting to avoid undue influence of temperature and humidity fluctuations. The emission of volatiles was analyzed with static headspace and gas chromatography–mass spectroscopy. The content of terpenes in undried sawdust decreased dramatically in the first days of storage, with 10 percent of the original amount left after 10 days. In dried sawdust, about two-thirds of the terpenes that remained after drying were released in the first 10 days. In sawdust, the hexanal concentration was negligible at first, became equal to the terpene concentration after 15 days, and reached a maximum after 40 to 50 days. Hexanal was then found in an equal amount to the remaining terpene content in undried sawdust; in dried sawdust, it was found in a much higher amount than the remaining terpene content. In pellets, hexanal content was consistently higher than the terpene content. The wood fuels were low-emitting for both terpenes and hexanal after 2 to 3 months. In conclusion, although terpenes have been assumed to be the predominant volatiles emitted during storage of solid wood fuels, hexanal from fatty acid oxidation is also of importance.
This article focuses on assessing the strength performance of glued-laminated (glulam) beams with E-glass fiber–reinforced polymer (GFRP) prestressing (prestressed GFRP-glulam beams) through bending tests and cross-sectional analysis. In addition to fifteen 6.7-m-long prestressed glulam beams, 15 GFRP-reinforced glulam beams and 15 unreinforced glulam control beams with nominally identical layups and 6.7-m lengths were tested to failure in four-point bending to provide direct performance comparisons. Load-displacement data and strains in the prestressed GFRP were monitored. The results of the tests show that the prestressed GFRP-glulam beams exhibited a 38 percent increase in allowable bending stresses compared with reinforced GFRP-glulam beams without prestress and an approximately 95 percent increase compared with unreinforced glulam beams. Both the prestressed and reinforced specimens exhibited an 8 percent increase in stiffness relative to the control specimens. Loss of prestress due to creep was examined for one specimen by monitoring GFRP strains over a 12-day period following fabrication. The total loss of prestress over this 12-day period was less than 2 percent, and the rate of prestress loss decreased during monitoring. The GFRP stresses predicted by a cross-sectional moment-curvature analysis of the prestressed and reinforced beams agree well with stresses inferred from measured strains. The results of this study show that prestressed GFRP reinforcement of glulam beams shows significant promise for practical applications.
A comparison of bending strength and modulus of elasticity (MOE) of squares with wanes to round timber was performed as part of a project on the use of round Scots pine (Pinus sylvestris L.) timber in structural frameworks. The study was based on 125 squares and 124 round logs from two sites at high altitudes and two sites at low altitudes in southern Norway. The effects of wanes were estimated by means of reduction in second moment of area and section modulus. Wanes had significant effect on both bending strength and MOE, but in both cases the effects were minor when compared with the effects of material properties. The reduction of bending stiffness due to wanes was almost as much as expected from lack of section, while the reduction of moment capacity was smaller. Squares with â…“ wane had both lower bending strength and lower MOE than round timber. According to how bending strength and MOE are calculated, differences due to wane were expected. The observed difference in bending strength was larger than expected through the lack of section, indicating that it was affected by material properties as well. The difference in MOE between round timber and squares with â…“ wane could be explained by the lack of section according to how these values are calculated. Origin had a significant effect on both bending strength and MOE.
Gaining additional knowledge of sawing methods that produce sawn boards with a radial grain is a significant problem today because such methods are rarely used. The current technology in Croatian sawmills is adapted to the standard live and cant sawing methods. Experimental in-mill sawing studies designed to monitor yield are subject to financial and technological restrictions. Therefore, simulated sawing is often required. This research presents the calculation method used to formulate a mathematical model that simulates sawing. The objective was to produce as many radial sawn boards as possible.
Overstocked small-diameter softwood timber in western US forests has created a serious forest health and fire hazard, and the costs of removing this material are high. One way to lower costs is to reduce loss because of warp on lumber sawn from these small logs. Using a green-gluing process, standard 38 by 89-mm (nominal 2 by 4-in.) pieces (2 by 4s) ripped from pressed panels of edge-glued (edge-glued-and-rip [EGAR]) boards sawn from small ponderosa pine (Pinus ponderosa) logs were evaluated for warp reduction. Material was bonded at high moisture content (MC) to simulate lumber freshly sawn from water-saturated logs and examine potential MC effects on wood–wood bonding. We selected a liquid, one-component, fast-curing, cold-setting polyurethane for green gluing wood. Results showed statistically significant reduction in bow (P < 0.001) and twist (P < 0.001) and no statistical difference in crook (P = 0.321) for EGAR boards compared with conventional 2 by 4s before planing. After planing and equilibrating, EGAR boards showed statistically significant increases in crook (P < 0.001) and bow (P < 0.001) but maintained a statistically significant reduction in twist (P < 0.001). Lumber quality decreased after planing and equilibrating to 12 percent MC. Because of high MC in flitches during the green-gluing process, bondline failures sometimes occurred, distorting the final results. High amount of bondline failure after planing and equalizing indicates this process is unfeasible as tested. Greater MC control during green gluing may reduce warp to allow more effective utilization of these small logs.
An innovative wood bending technology has been developed by the University of Melbourne, within the Cooperative Research Centre for Wood Innovations, which involves the microwave softening of wood components to make them pliable for bending, the use of an automated bending machine, and microwave drying of bent furniture components. This article presents the results of a study that assessed bending quality and that determined the minimum radius of bending curvature of eight plantation and regrowth Australian timbers using the microwave wood bending process: Eucalyptus nitens, Eucalyptus saligna, Eucalyptus marginata, Eucalyptus diversicolor, Pinus radiata, Nothofagus cunninghamii, Atherosperma moschatum, and Acacia melanoxylon. Based on the results of the study, the microwave bending performance of the wood species was rated as follows: (1) E. diversicolor, very good (sanding or small amount of machining was required); (2) P. radiata, Atherosperma moschatum, and E. nitens, decent (machining was needed); (3) Acacia melanoxylon and N. cunninghamii, satisfactory (fairly large failures occurred but these were removed by machining); and (4) E. saligna and E. marginata, very bad (large failures which could not be removed by machining). Overall, the results of the study on the bending performance capabilities of plantation and regrowth Australian timbers showed several differences compared with the literature data relating to the bending abilities of the relevant old growth timbers.
Material costs when cutting solid wood parts from hardwood lumber for secondary wood products manufacturing account for 20 to 50 percent of final product cost. These costs can be minimized by proper selection of the lumber quality used. The lumber quality selection problem is referred to as the least-cost lumber grade mix problem in the industry. The objective of this study was to create a least-cost optimization model using a design that incorporates a statistical approach to address shortcomings of existing models using linear optimization methods. The results of this study showed that optimal solutions tend to use as much low-quality lumber as possible to minimize costs. Comparison of results from this new least-cost grade mix model with other existing least-cost lumber grade mix models has shown that the new model results in lower-cost solutions.
Computer-aided manufacturing (CAM), in which computer-aided design (CAD) and computer numerically controlled (CNC) machining are integrated for the production of parts, became a viable option for the woodworking industry in the 1980s. To determine if using computer-based technologies in wood products design and manufacturing can streamline the many phases of production, a survey was conducted in 2006. Sixty-three percent of survey respondents indicated they use CAD. Even in the very small woodworking companies, CAD use was not uncommon, with 46 percent of them using CAD technology. Web sites and Web-based sales were being used by 41 percent of the survey respondents. Forty-one percent also used CNC machining. A much higher percentage of the large companies used CNC, considering that of all companies with 50 or more employees, 93 percent used CNC machining. CAM was the only other computer technology utilized by more than 20 percent of the respondents.
The forest products industry is a vital component of Virginia's economy, and logging businesses, as the suppliers of raw material, are an extremely important part of this industry. How they operate, their challenges, and their ability to adapt to changing economic conditions are of interest to the entire forest products industry. To further our understanding of how Virginia loggers operate their businesses, we developed and mailed a repeatable survey instrument during the summer of 2009 to participants currently enrolled in the Virginia Sustainable Harvesting and Resource Professional logger program. Due to Virginia's distinct geographic makeup and its impact on logging system design and characteristics, results were segmented by three physiographic regions: mountains, piedmont, and coastal plain. Ninety-eight percent of respondents were men, 94 percent were Caucasian, and 49 years was the average age. Logging businesses operated with an average of 1.2 crews and 3.3 workers per crew, which varied across each region of the state. The type of harvesting system used also varied between regions as did the products harvested, production levels, use of technology, and time spent planning harvests and implementing best management practices. Business owners also indicated that their greatest challenges were finding markets for their products, the increasing costs of fuel and operation, and the prospect of fewer markets in the future. Survey results provided further insight into the characteristics of Virginia logging businesses and the challenges they face, while establishing a baseline dataset for future comparison.
A mail survey of Appalachian hardwood product exporters was conducted in the fall of 2008 to analyze the export practices for Appalachian hardwood products, specifically the volume of hardwood products exported to the Chinese market, their preferred species, and potential and existing trade barriers between US producers and Chinese customers. Results of the survey showed that the most frequent export destinations of Appalachian hardwood products were Europe, China, Canada, Mexico, and Japan. In 2007, approximately 11.4 million board feet (MMBF, Doyle scale) of hardwood logs and 145.3 MMBF of hardwood lumber were exported to China by the respondents. Approximately 37 percent of the respondents who exported hardwood products to China exported red oak logs, followed by white oak, black walnut, black cherry, and hard (sugar) maple. The top species of hardwood lumber exported to China were red oak, white oak, yellow poplar, black walnut, hickory, cherry, hard maple, and soft maple. Respondents indicated that transportation freight costs and payments are the limiting factors when considering expanding business overseas. The continued decreasing hardwood price has put more pressure on hardwood products exporters to maintain profit margins. Because of the current economic downturn, hardwood production in the Appalachian hardwood region has declined by more than 40 percent. Exports of hardwood products to China will be affected to some extent. However, it is expected that China will remain an important overseas market in the near future.