Harvest, Sort, Process

Nondestructive evaluation (NDE) is the science of identifying physical and mechanical properties of a material without altering its end-use. We are developing NDE technology to detect decay in standing small-diameter trees. This technology is also being developed to evaluate wood product quality, such as its suitability for veneer manufacture.

Log-Sort Yard: Successful log-sort yards promote better utilization and improve value recovery of the timber resource. A log-sort yard is a good mechanism for sorting SDU material into various uses. We developed a guidebook on how to plan, develop, and operate a successful log-sort yard. This guide-book is applicable to small-diameter softwoods in the West   and underutilized species in forests nationwide.

Log processing efficiency is critical because the purchase of small-diameter material is the most expensive manufacturing cost. We developed a computer simulation model, Best Opening Face (BOF), to determine the BOF for the sawing process and to help recover the most lumber from the log. BOF is the most widely adapted sawmill model for simulating the process of recovering dimension lumber from sound, small-diameter softwood logs. � 

Lumber(>6-inch dbh) 

Grade/Recovery: Small-diameter timber is a nontraditional resource; therefore, appropriate uses cannot be determined until its properties and characteristics are understood. We conducted grade yield and recovery studies to determine the best lumber grades for small-diameter timber based on a particular species. Studies indicate that high quality material can be found within small-diameter timber. Some material is suitable for high-valued engineered wood products, such as trusses and glued-laminated (glulam) timber; some is suitable for high-valued flooring, panel- ing, and furniture. Some material is not suitable for either use.�

Kiln-drying small-diameter lumber presents different challenges than drying lumber from large-diameter trees. Lumber from small-diameter logs is more likely to warp, is more prone to splitting, and has less exposed end-grain. We are developing procedures to reduce these problems.

Engineered wood products, such as laminated veneer lumber, strand lumber, and glulam beams, are potential high-valued products made from SDU material. We are evaluating the suitability of SDU material for such products by testing new lay-ups and design procedures.

Roundwood (<6-inch dbh) 

Air-drying is an economical way of drying small-diameter roundwood. Drying times depend on seasonal conditions. We are developing air-drying time estimates based on ambient temperature and relative humidity. 

Mechanical Grading: Currently, structural grading for logs to be used in homes is based on visual methods. However, this method is probably too conservative. Our research shows that compared with visual methods, a mechanical grading system developed for logs based on using a combination of visual methods and nondestructive testing is more precise and can lead to a more efficient use of the resource.� � 

Strength/Stiffness: Limited knowledge of strength and stiffness of small-diameter roundwood presents an obstacle to its acceptance in design as a structural component. We are collecting data to characterize the strength and stiffness of small-diameter roundwood for use in design. Results will be used to develop standards for deriving design stresses.� 

Connectors: Most commercial connectors are intended for use with sawn lumber. However, efficient use of small-diameter roundwood as a structural building material requires new types of connector systems, such as dowel-nut, finger joint, nailed metal plates, and threaded dowel rods. We are developing a database to derive design values for connectors that will be used in roundwood demonstration structures.

Preservative Treatment: Our research indicates that suppressed-growth grand fir posts can be effectively treated with several common preservatives (e.g., ACZA, copper naphthenate). Acceptable treatment was not achieved with CCA. Treatability is affected by growing conditions.

Demonstration Projects

Our technology is often showcased through demonstration projects with small businesses and in communities. The aim is to help develop businesses that use these technologies. Examples of our demonstration projects follow:
-- Partnered with Western communities to build 2 round-wood demo structures displayed as information kiosks at 2002 Winter Olympics (designs available to public).
-- Built 60- by 35-ft roundwood pavilion in Colorado.
-- Displayed SDU flooring and furniture in our demo house.
-- Designed trusses for a school greenhouse in New Mexico-- -- Developed roundwood engineering designs for a recreational structure in Oregon and a library in Montana.�

Bridges

Road: We have been involved in developing timber bridge systems for secondary wood species for 13+ years. SDU species are especially suited for construction of glulam stress-laminated decks and deck panels for road bridges. To date, numerous bridges have been built throughout the United States using SDU species. Future research is directed toward adapting these bridge designs to additional SDU species and will include developing economical standard design plans.

Pedestrian: We developed engineering designs using SDU material for a 40-ft pedestrian bridge and are working on engineering designs for an 80-ft pedestrian suspension bridge.

Composite/Panel Products

Composites can be made from a variety of wood and wood-based raw materials. Our current research focuses on (1) exploring the properties of thermoplastics filled with wood fibers from SDU material; (2) developing technology for industrial application of juniper fiber materials; (3) expanding wood-fiber thermo-plastic composites to exterior applications by incorporating a naturally occurring preservative and termicide.�

Wheelchair Accessible Playground Surface: Using SDU material, we developed a new, cost-effective alternative to traditional engineered wood fiber, the preferred playground cushioning material. Preliminary results show that the surface yields a low impact and is resilient for wheelchair and walker accessibility.

Signage Using Western Juniper: Historically, juniper has been used for firewood and fence posts, and the high costs of harvesting and processing have limited attempts to further develop this waste wood. We developed a composite panel made from juniper and recycled plastic. This composite panel is resistant to damage from porcupines and gunshots and has a high level of moisture resistance, dimension stability, and stiffness. Signs made from test composite panels are being used in several National Forests.

Water Filtration System: We developed wood fiber filters made from SDU material that remove water pollutants from water, such as agricultural runoff from watersheds, mining sites, and pesticides from surface water in the cranberry industry, and nitrates and ammonia in recirculated water from fish aquaculture. Such systems are adaptable to small, rural enterprises for local sites with erosion problems.

Structural Panel Products: Using SDU material, we developed a novel three-dimensional sandwich panel that exhibits a high level of strength and stiffness. This type of panel has potential for use in products such as pallets, bulk bins, heavy-duty boxes, shipping containers, packaging supports, wall panels, roof panels, partitions, displays, desks, shelves, tables, and doors.

Pulping

Our initial research studies show that the quality of pulp from small-diameter trees can be used as potential raw material in kraft pulp mills. Pulp mills require large amounts of water to operate; therefore, geographical location is an important role in the viability of the pulp chip market.

Biopulping: Biopulping is the fungal treatment of wood chips before mechanical pulping. Biopulping decreases energy consumption by at least 30% and significantly increases paper strength properties. Our research indicates that biopulping has potential for use with SDU species.

POMs: Conventional pulping has not been considered feasible for mixed SDU species because chemical pulping rates are not uniform. Some species are more difficult to delignify than are others. However, our exploratory work shows that POMs (polyoxometalates) are effective at pulping and bleaching mixed SDU species. POMs are nontoxic and environmentally friendly chemical compounds, which use very little water.

Compost and Erosion Control

Important uses for wood waste material (residue) are compost or mulch products. We are exploring small-scale alternatives to composting operations, such as passive aeration, that is efficient at compost production but does not require a large capital investment. In addition, we published a market analysis of erosion control mats. Because erosion is a worldwide problem, there is no limit to potential markets for erosion control products. We are also examining the feasibility of developing new equipment for in-woods processing of SDU material for erosion control products.

Energy

Biopower Systems: We partnered with the U.S. Department of Energy to demonstrate small-scale, biopower units that produce electricity by burning wood chips. Working together, this technology will develop more quickly through field demonstrations that are ongoing at 7 locations throughout the United States. These demonstration units use advanced downdraft gasification technology to convert the energy in wood chips into a clean, gaseous fuel suitable for use by a variety of generators. The current prototype of this biopower unit can produce 15 kW of electricity and up to 50 kW of useful heat. Biopower technology can help improve forest health, increase sustainable domestic energy production, and help form new businesses.

Fuels-To-School Program: We are collaborating in a pilot project that promotes wood-fueled heat in schools and other public buildings. A wood-fueled system has been installed in a school in Darby, Montana. The heat source is from SDU material available from that area.

Contact: Susan LeVan, Forest Products Laboratory � (608) 231-9504 � www.fpl.fs.fed.us

February 2003