Wood Composites Home
We’re at the forefront of testing and manufacturing new, innovative, and sustainable forest products to revitalize and diversify Maine’s forest-based economy.
The UMaine Advanced Structures and Composites Center has a complete Wood Composites Pilot Line allowing the production of up to 4’ x 8’ oriented strand board (OSB), laminated veneer lumber (LVL), particleboard, Wood Fiber Insulation, and other cellulosic composites on a near-industrial scale.
Companies may opt for complete manufacturing – from log to panel – or select only certain unit operations, such as stranding, drying, and screening. Recent studies include the use of innovative bio-based resin systems, wax substitutes, fire retardants, and residuals to produce value-added products.
Wood Composites Pilot Line
Log Delivery & Conditioning
Companies may deliver tree length or pre-cut logs with a maximum diameter of 12”. Approximately ten 5’ long x 12” diameter logs can be soaked and/or heated at a time to 150°F.
Stranding & Screening
A Carmanah 12/48 Lab Strander converts logs into strands from 3” to 12” in length for OSB/LSL production.
A 48” ring holds two knives that protrude into the inner face of the ring. Strands are produced by advancing the log through the rotating ring at a specified rate. Projection of the knives in combination with ring speed determines the flake thickness, and width is achieved by selection of the appropriate counter knife angle, and strand length through the use of scoring knives.
Strands are dried on a Koch Bros. in-line conveyor dryer. The forced-air dryer is 3’ wide x 10’ long, with an additional 4’ of infeed and outfeed. The dryer can evaporate up to 250 lbs. of water per hour, at a maximum temperature of 325°F and a fan capacity of 7,500cfm.
A 5,000 board foot, Nyle dehumidification dry kiln is also available bringing strands to within +/- 1% of the target MC, usually within 24 hours.
Resin is applied to strands using one of two Coil spinning disk atomizing resin blenders (3’ x 6’ and 5’ x 10’). The blender drum can be rotated up to 20 rpm, and the spinning disk atomizer to 15,000 rpm. Either 30 or 120 lbs, for the small and large blender respectively, of dry strands, can be blended at a time. The resins (normally pMDI or PF) and waxes are sent to the blender by means of a peristaltic pump. Wax emulsions are introduced using an air atomizer.
Boards are pressed in one of two presses:
450 ton 34″ x 34″ Dieffenbacher steam injection press: This press system is controlled by a PressMan system. Mats can be pressed with thermal oil (up to 450°F) or steam injection (up to 250 psi steam pressure). Steam injection allows for the pressing of thick strand composites.
4’ x 8’ Erie Mill & Press: 1800 ton hydraulic press (provides 725 psi on a full-sized 52”x100” mat). The press is PLC controlled, with complete data collection for a printout of press scheduling data and graphs. The press can be controlled in either position or pressure control. Energy is provided either by hot oil (up to 500°F) heated platens or radiofrequency (10 kV, 30 kW Thermex-Thermatron system).
Conditioning & Testing
Boards/panels are conditioned prior to testing in a walk-in environmental chamber.
The UMaine Composites Center, an ISO 17025 accredited testing laboratory and has a full suite of ASTM wood products testing capabilities within its accreditation scope (such as ASTM D143, D198, D1037, D4761, etc.). A full list is available here.
Wood Composites Manager
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Wood Composites Overview
The ASCC’s research roots are in Wood Composites. Since opening in 1996, the ASCC has conducted hundreds of federal and industrial trials on wood and wood-based composite materials. Prototype products such as oriented strand board (OSB), laminated strand lumber (LSL), particleboard (PB), laminated veneer lumber (LVL), glulam, plywood, and cross-laminated timber (CLT) are manufactured and tested on-site using the ASCC’s wood composites pilot line.
A significant area of recent research is the development, energy performance, and market prevalence of cross-laminated timber (CLT), a large-scale, prefabricated, solid engineered wood panel consisting of alternating, layered lumber or structural composite lumber which offers the potential to reduce carbon footprint compared to that of steel and concrete in building construction. The ASCC plans to use CLT as the main structural material for our 90,000 ft² GEM Factory of the Future addition.
The Maine Mass Timber Commercialization Center
The MMTCC brings together industrial partners, trade organizations, construction firms, architects, and other stakeholders in the region to revitalize and diversify Maine’s forest-based economy by bringing innovative mass timber manufacturing to the State of Maine. The emergence of this new innovation-based industry cluster will result in positive economic impacts on both local and regional economies, particularly in Maine’s rural communities
Maine Mass Timber Research
Structural Performance of Hybrid CLT
Students and staff at the University of Maine manufactured and performed mechanical property testing to determine the feasibility of using lumber from Northeastern U.S. forests and laminated strand lumber (LSL) in hybrid CLT.
One outcome of this study was a better understanding of how CLT panels may be designed using various wood and engineered wood products to maximize the attributes of the specific laminae, and therefore efficiently maximize the mechanical and physical properties of the final CLT panel. For example, test results indicated that the use of LSL as the cross-ply material increased the perpendicular-to-grain shear strength of CLT, which significantly enhanced panel capacity.
Qualification of New CLT E-Grades
The UMaine Advanced Structures and Composite Center is currently working on a project to introduce two new grades of cross laminated timber (CLT) using MSR-graded Spruce-Pine-Fir South (SPF-S) lumber produced in Maine. These grades are designed to be equivalent to existing CLT manufactured with southern yellow pine or Douglas-fir, species known for their high stiffness and strength. Introduction of these grades will make Maine/New England more competitive in the CLT market.
Effect of Gaps
Research at UMaine is currently underway to investigate the effect of gaps between the inner layers on the mechanical properties of CLT. Secondary objectives include the development of modeling techniques applicable to a range of gap sizes to predict said effects, and the determination of whether significant reductions in CLT shear and creep performance, due to the existence of edge gaps of CLT manufactured with lumber, can be mitigated with alternate materials such as SCL.
Blast Testing of CLT
In 2016, WoodWorks conducted a series of live blast tests on three two-story CLT structures at Tyndall Air Force Base to demonstrate the effectiveness of CLT over a spectrum of blast loads.
The University of Maine supported the project by conducting static/quasi-static testing and data analyses and aiding in the design and on-site execution of dynamic blasting.
Mass Timber Blast Testing Phase 2: Test 7 – 610 lbs of flake TNT with config changes #2
Maine may lead mass timber ‘revolution’ to reduce construction’s carbon footprint
Mass timber lends itself to carbon-emissions reductions and aesthetic design, SMRT Architects & Engineers President Ellen Belknap said during a recent E2Tech presentation.
What is Mass Timber
Many architects and engineers believe that we are now in the “beginning of the timber age” where “plyscrapers” will soon be dotting city skylines all over the world. These tall wood buildings are a result of “mass timber” – a category of construction characterized by the use of large wood-based panels for wall, floor, and roof construction.
Mass Timber Products
Benefits of Mass Timber
Mass timber products use renewable and sustainable resources instead of fossil-fuel intensive materials. This equates to a lighter carbon footprint.
Mass timber construction is faster, leading to less construction traffic and fewer workers than similarly-sized concrete construction projects.
The fact that mass timber weighs less than other materials offers some structural advantages, such as smaller foundations and lower forces for seismic resistance.
Mass timber provides inherent fire resistance due to the nature of thick timber to char slowly and at a predictable rate. This allows these systems to maintain their structural integrity for significant time durations.
Wood Fiber Insulation
UMaine and GO Lab have partnered on R&D programs and prototyping efforts since 2018. Evaluations have investigated the effect of various manufacturing parameters, adhesives (including bio-based) type, and loading on mechanical and physical properties of wood fiber insulation.
Wood fiber insulation (WFI) based products have been produced and used in European countries, mainly in Germany, Austria, and Switzerland, since the mid-1990s. WFI is made in three forms, 1) loose-fill, 2) batts, and 3) rigid boards. WFI, which has grown into a 0.7 billion USD market in Europe, is currently being imported into the U.S., but high shipping costs have kept it an expensive niche product. Emerging domestic manufacturing is projected to make WFI a cost-neutral, drop-in replacement for fossil-based insulation boards, such as extruded/expanded polystyrene foam (XPS/EPS). Wood fiber insulation has better ecological credentials, as well as several performance advantages, over the fossil-based conventional insulation materials, including better sound attenuation, and vapor openness. WFI also can utilize a wide range of species, providing a critical outlet for a lower value, underutilized species which can have a positive impact on overall forest health. Finally, WFI is a prime potential consumer of residuals, which for many regions have found their traditional outlets disappearing (e.g. paper chips, pellets, biomass energy plants).
GO Lab, Inc., a building products manufacturer based in Belfast, Maine, is currently building the first WFI manufacturing facility in the U.S. in central Maine to demonstrate the market. Their wood fiber insulation is to be comprised of greater than 90% softwood fiber, will be renewable, recyclable, non-toxic, and is expected to meet all performance requirements of common commercial construction insulations. Once running at capacity, GO Lab’s production facility in Maine will consume approximately 100,000 green tons of softwood chips annually while addressing just 0.6% of the US insulation market.
NELMA Norway Spruce Testing
Norway Spruce joins the spruce-pine-fir south (SPFS) lumber grouping. Norway Spruce is the first new, major US-grown species of softwood to be fully tested for strength values for inclusion in an existing lumber grouping since the initial process for assigning design values by way of lumber testing of wood samples began in the 1920s.
All testing and data analysis (per ASTM D1990) was conducted at the UMaine Advanced Structures and Composites Center. The inclusion of Norway Spruce was approved by the American Lumber Standards Committee (ALSC) on October 20, 2016.
Researchers at the UMaine Composites Center tested 1,320 boards (in bending and tension) cut from trees harvested in Maine, Vermont, Wisconsin, and four regions of New York state for the Northeastern Lumber Manufacturer’s Association (NELMA).
UMaine evaluated Norway spruce to determine if it met industry standards for inclusion in the SPFS grouping of wood species for construction-grade dimensional lumber.
Inclusion in the SPFS grouping means tens of millions of “new” trees will enter the North American lumber economy for the first time.
During the Norway Spruce testing process, a total of 1,320 full-sized pieces of 2x4s, 2x6s, and 2x8s of both Select Structural and No. 2 grades were tested to failure. Of the 1,320 pieces, 658 were tested for bending, and 662 were tested for tension. The results were used to establish strength values for the species for all 6 major design categories:
– Modulus of Elasticity
– Fiber Stress in Bending
– Tension Parallel to Grain
– Horizontal Shear
– Compression Parallel
– Perpendicular to Grain
“In the forest, Norway Spruce is easily recognizable by its large, drooping ‘branchlets.’ Fun fact: the Rockefeller Center Christmas Tree has been a Norway Spruce the vast majority of times over the last several decades, including the 2015 tree, a 78- footer from Gardiner, New York. Once cut into logs, Norway Spruce is virtually indistinguishable from native eastern spruce species, with even the most experienced of graders not able to discern one species from the other. Grade-wise, approximately 65% of Norway Spruce is expected to be graded at #2 and above, making it a strong, promising addition to the SPFs category. The primary market focus for the lumber will be on home construction applications such as wall studs, floor and ceiling joists, and industrial applications.” – Courtesy of NELMA.
“This is a momentous occasion for the building industry. The addition of a new species hasn’t happened in almost a century, and it’s been a very exciting year as we’ve worked to shepherd it through testing and bring it into the mainstream.”JEFF EASTERLING, PRESIDENT OF NELMA
LEARN MORE ABOUT THE EXCITING OPPORTUNITIES AT THE ASCC