Wood and Fiber Science (E-Journal)
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EFFECT OF TREATMENT POSTFIXATION PRACTICES ON COPPER MIGRATION FROM ALKALINE-COPPER-TREATED DOUGLAS-FIR LUMBER
Get PDFThe potential for preservative migration from treated wood exposed in or above aquatic environments has become a major concern in some parts of the United States. Best management practices (BMP) were designed to decrease the potential environmental footprint of treated wood, but there are few studies assessing the efficacy of these processes. The effects of applying various post-treatment BMP heating processes on loss of copper from copper azole Type B (CA) and alkaline copper quaternary compound Type B (ACQ)-treated Douglas fir were evaluated using a simulated overhead rainfall apparatus. This study examined the initial phases of wetting, which previous studies have shown to pose the highest risk to aquatic life. Immersion of CA-treated wood in hot water or a dilute ammonia solution was associated with lower levels of copper in rainfall runoff than steaming or kiln-drying, whereas steaming was associatedhigher copper levels. Similar trials with ACQ revealed that various heating treatments produced results that were similar to those found with air-drying. The results suggest that there might be opportunities for decreasing copper losses from CA-treated wood through further refinements in post-treatment BMPs. They also indicate that post-treatment heating processes that do not dry the wood still produce products that experience copper losses similar to those found with air-dried material
OVERCOMING BARRIERS TO BIOMASS COGENERATION IN US WOOD PRODUCTS INDUSTRY
Get PDFCogeneration, also known as combined heat and power, is the simultaneous generation of electric and thermal energy from the same fuel source. Some proven benefits of cogeneration are much higher efficiencies than conventional power generation and its ability to facilitate distributed energy and lower energy costs. Also, when cogeneration is fueled with wood biomass, there are additional environmental benefits such as using a renewable energy source and lower greenhouse gas emissions. However, only a small number of wood product manufacturers (North American Industry Classification System codes 321 and 337) have adopted this technology. In this study, drivers, perceptions, and barriers for cogeneration were investigated to gain understanding of the reasons for the low adoption of this technology among wood product manufacturers. Interviews of experts and companies were conducted to identify and understand major topics of cogeneration adoption within the industry. Subsequently, a nonprobability, target survey of nonadopters was carried out to identify operational characteristics, perceptions about benefits of cogeneration, and barriers to its implementation. Findings show that economies of scale and coincidence between thermal and electric loads are some of the major factors for cogeneration feasibility. Main barriers identified were the initial investment and complexity, companies’ return-on-investment requirements, utility tariff policies, and inadequate policies and incentives. Another major finding was a lack of awareness and knowledge about cogeneration, which presents organizations that support the forest products industry with an opportunity to provide education and outreach. However, because of the small sample size (52 responses), generalization of these results to the population of interest is not feasible
Cradle-To-Gate Life Cycle Assessment of Switchgrass Fuel Pellets Manufactured in the Southeastern United States
Get PDFDeveloping renewable energy sources with low environmental impacts is becoming increasinglyimportant as concerns about consuming fossil fuel sources grow. Cultivating, harvesting, drying,and densifying raw biomass feedstocks into pellets for easy handling and transport is one step forward in this endeavor. However, the corresponding environmental performances must be quantified. This study presents cradle-to-gate life cycle inventory and impact assessment data for switchgrass fuel pellets potentially manufactured in the US Southeast. Because there are no current manufacturers of switchgrass pellets, inventory data were based on field trials of cultivation and harvest of switchgrass combined with a separate study of wood pelletization. Energy inputs for cultivation and harvest of switchgrass were collected by survey from farmers in Tennessee and represent the years 2008, 2009, and 2010. Data for pelletization were taken from a report on wood pellet manufacturing in the US Southeast. To produce 1.0 Mg of pellets that contain 18.0 GJ of potential bioenergy, 4.1 GJ of fossil energy inputs were required. Switchgrass crops require relatively little energy and inputs for the cultivation and harvest processes. The majority ofthe environmental burdens are associated with drying and pelletizing the raw material
Development of Creep Models for Glued Laminated Bamboo Using the Time-Temperature Superposition Principle
Get PDFThis paper describes the development of creep models for glued laminated bamboo (GLB)using the time-temperature superposition principle (TTSP). Creep (15 min) and recovery (45 min) data were obtained at constant temperature levels ranging from 25 to 65C. The moisture contents of specimens for testing were dry, 7% and 12%. The individual curve at each temperature was plotted against the log-time axis to obtain a master curve. A nonlinear regression analysis was used to estimate the model parameters. Then the individual temperature master curves were shifted again to a reference MC to construct an overall master curve using time-temperature-moisture principle. The relation of temperature and moisture shift factors loga (T, M) to temperature (T) and MC (M) was analyzed. The results show that the TTSP was successfully applied to GLB tested at different moisture contents
Hot-Pressed Dowels in Bonded-In Rod Timber Connections
Get PDFBonded-in rod connections are becoming a more and more popular method in the constructionindustry for connecting timber. These connections are favored for their versatility. The most commonly used system is bonded-in steel rods, which are typically prone to brittle failures. The aim of this study was to investigate the potential of hot-pressed wooden rods as an alternative to conventional steel bonded-in rod systems, which have better material harmonization and exclude the use of adhesives. The proposed connection was applied to the practical situation of a beam splice in flexure to determine its potential. The results showed that ductile failure mode occurred at high rotations at which peak loads were displayed. A theoretical model was developed and found to be accurate compared with the experimental results. This type of connection has good ductility, which suggests its application in domestic timber framing in regions of high seismicity would be practical
SHEARING BEHAVIOR OF STRUCTURAL INSULATED PANEL WALL SHELLED WITH BAMBOO SCRIMBER
Get PDFIn this study, shearing behavior of a structural insulated panel (SIP) wall, which consisted of a Styrofoam core board, shell panel of bamboo scrimber, and frame of Spruce–Pine–Fir dimension lumber, was tested under monotonic and cyclic loads. Results showed that the SIP wall failed at similar positions under two loading modes, although more serious destruction occurred under cyclic than monotonic load. There was a linear relationship between load and displacement at the initial loading stage, which indicated that the wall worked under the elastic state. At a later loading stage, bearing capacity and rigidity decreased as a result of wall slip. Shearing strength under monotonic and cyclic loads was 20.0 and 15.8 kNm-1, respectively, which met the requirement of the standard code for design of timber structures. Energy consumption of the SIP wall covered with bamboo scrimber was 11,556.6 Jm-1
Effect of Wetting on Performance of Small-Scale Shear Walls
No full textWood shear walls are the main lateral force-resisting system for wood-frame construction. Water intrusion and subsequent decay around connections can significantly impact shear wall behavior, but these problems are seldom studied. In this study, effects of water intrusion and fungal attack on shear wall capacity were examined using small-scale (610- _ 610-mm) shear walls that were monitored with time using destructive monotonic tests. Results were compared with tests of dry and water control samples. Although fungal colonization was not successful under the conditions tested, wetting (with or without fungal inoculation) produced interesting effects on shear wall capacity. Wetting alone initially increased shear wall capacity, possibly because of fastener corrosion. Observations and digital image correlation data suggest that tensile forces in the uplift corner of the shear walls governed failure modes, which were primarily nail withdrawal, nail pull-through, flake debonding, and cross-grain tension. Wetting affected rigidity of oriented strandboard and led to more frequent nail pull-through. Although failure loads did not differ between the groups, failure modes and displacement at maximum load suggested decreased performance of wetted shear walls. The results suggest that slight amounts (8% overall) of wetting do not negatively affect shear wall performance. However, the effects of prolonged wetting on capacity merit further study
Investigating Surface Quality of African Mahogany (Khaya Ivorensis) From Ghana using Stylus and Deflectometry Techniques
Get PDFStudies and information are limited on quantitative evaluation of machined surfaces of tropicalAfrican hardwood species such as mahogany (Khaya ivorensis). In this study, surface quality of mahogany from plantations and natural forests that were harvested near Pra-Anum Forest Reserve, Ghana was evaluated using the stylus profilometer and Optimap deflectometry techniques. The evaluation was made at three different height levels: bottom, middle, and top portions of harvested trees. The average roughness, mean roughness depth, maximum surface roughness, core roughness depth, reduced peak height, reduced valley depth, total height of roughness, and maximum depth of roughness motif were estimated on tangential surfaces of the samples after sanding using sandpaper of grit size P150, P180, and P 280. Texture values were also measured at different wavelengths using an optimap device. Based on the results of statistical analysis, the selected roughness parameters varied significantly at different portions of wood samples at 95% confidence level in both plantation and natural samples except reduced peak height parameter. Results also revealed that mean roughness parameters at the bottom and middle portions of the trees had relatively lower values in plantation samples than in natural samples. This implies smoother surfaces for the plantation samples. At the top portion, however, plantation samples had relatively higher values for most roughness parameters than did natural samples. Texture values at different wavelengths showed statistically significant variation along the stem for both natural and plantation samples at 95% confidence level. Although some limitations exist in using Gaussian amplitude filters to eliminate deep sinks in the profile, the data gave a good indication of surface quality and comparison of surfaces of mahogany samples
EFFECTS OF DIFFERENT FLAVONOID EXTRACTS IN OPTIMIZING TANNIN-GLUED BARK INSULATION BOARDS
Get PDFEfforts in decreasing energy consumption in buildings have created a market environment that favors insulation materials made from renewable resources. Tree bark is a naturally highly optimized material that can serve insulation needs. Thus, bark insulation panels have been produced from larch bark and bonded with a formaldehyde-free tannin-hexamine resin. Quebracho and mimosa tannins, containing different levels of hexamine, were mixed with bark particles at different ratios, and cured in a hot press for various press times. Mechanical and water-related board property evaluation showed mimosa tannins to be advantageous in terms of panel performance. This was supported by Fourier transform infrared (FTIR) spectroscopic analysis of tannin polymers, which provided insight into the chemical activation by a hardener and possible rationale for the better performance of mimosa resin. Evaluating thermal conductivity of the panel showed that its dependence on temperature was comparable with commonly availableinsulation materials
Content Analysis of Decking Material Business-To-Business Advertisements: 2002-2014
No full textThis study provides a longitudinal perspective on business-to-business advertising content contained in 82 Professional Deck Builder (PDB) decking ads from 2002 to 2014. Specifically, this study used content analysis to determine the presence–absence of a predefined set of 28 attributes and if the primary advertisement appeal was rational or emotional among five decking material categories—plastic lumber (PL), treated lumber (TL), wood–plastic composite (WPC), tropical hardwood (TH), and aluminum–steel (AS). Study results showed that the seven most-mentioned decking attributes were aesthetics beauty (56% of the 79 PDB advertisements), durability–long life (45%), color options (37%), warranty–guarantee (34%), environmental friendliness (34%), easy–low maintenance (33%), and strength–stiffness (30%). By decking material category, the most frequently mentioned attributes for TL were environmental friendliness, aesthetics, and durability. WPC advertisements featured content regarding color options, aesthetics, and warranty, whereas PL advertisements most frequently addressed durability, aesthetics, color options, low maintenance, and warranty. TH decking advertisements highlighted aesthetics, durability, low maintenance, and strength, and AS decking advertisements focused on aesthetics, durability, low maintenance, and low heat retention–stays cool. Results also showed that rational vs emotional appeals by decking advertisements in PDB from 2002 to 2014 were fairly even with 57% rational and 43% emotional. By decking material, TH and TL decking advertisements favored the rational appeal approach and WPC decking used the greatest percentage of advertisements with emotional appeal