The AEC industry has recently discovered a new appreciation for wood and its applications in mass timber and tall construction. But the material’s relatively lightweight and carbon-storage capabilities are also prompting innovators and scientists to experiment with new uses and manipulations. From readily available commercial products to highly modified materials, ARCHITECT highlights inventive examples of wood products and technologies below.
For building interiors, based in Milan Wood-Skin makes Fold the panels, a multi-dimensional system of triangulated wood clad modules designed for vertical and horizontal applications such as walls, ceilings and railings. Delivered flat-packed, 3D panels are structurally supported by an aluminum frame and come with a variety of surface options including sound deadening felt and cork. The company also offers mesh sheets, a similar product that offers a wider variety of geometric patterns and surface materials. Subdivided into smaller, self-similar units, mesh sheets fall somewhere between rigid panels and soft textiles. According to the manufacturer, they allow “the construction of architectural membranes with the same functional properties and appearance as ‘macro-tissues'”.
San Francisco-based Smith & Fong (also branded Plyboo) offers decorative wall panels called Fractal. The triangular modules of this product are dimensionally flat, but provide visual interest via groove patterns routed in parallel lines. The 24 inch by 24 inch by 34 inch, 3/4 inch thick isosceles triangles are made of Moso bamboo and are available in various colors and line pattern scales. The modules can be oriented to produce optical illusions of depth and movement. The Smith & Fong website includes a Fractal design tool that allows designers to simulate custom models in various room configurations.
Requiring a higher level of processing, wood is combined with other materials to create new hybrids. Suffolk, United Kingdom lignacite manufactures concrete masonry units made from recycled wood chips, other waste materials, sand and gravel. The company reports that its Carbon Buster block is carbon negative, sequestering more carbon dioxide than its production emits. In addition to carbon-rich wood chips, the block consists of Carbon8 pellets made from a combination of cement, sand and water storing carbon dioxide. Based on data from a Carbon and Energy Inventory conducted at the University of Bath, the Lignacite masonry unit compares quite favorably to typical concrete or brick masonry units.
Researchers from the University of British Columbia (UBC) also made a wood-based concrete. Rather than creating masonry units, scientists fashioned non-structural panels intended to replace wall panels, countertops or flooring. UBC’s wood comes from local trees ravaged by the mountain pine beetle (MPB). “Normally, cement repels organic matter, like wood,” said Sorin Pasca, a master’s student in ecosystem science and management working on the project. “But for some reason, cement sticks to lodgepole pine, and that compatibility is even stronger when the tree has been killed – or you might say, enhanced – by the mountain pine beetle.” Unlike the Lignacite product, MPB Wood Concrete uses wood chips instead of gravel as the aggregate. It can therefore be modified using typical woodworking tools, allows nailing without pre-drilling and is water resistant. The material also paves the way for the commercialization of MPB wood, which sawmill operators struggle to process conventionally.
At the University of Maryland, engineers have developed a process to make wood 12 times stronger and 10 times stronger. According to Liangbing Hu, professor of materials science and engineering leading the research, the modified material “could be a competitor to steel or even titanium alloys, it is so strong and durable. It is also comparable to carbon fiber, but much cheaper.The method involves the removal of lignin, the intercellular glue of the wood, and subsequent compression at low temperatures.The resulting material is reduced to 20% of its original thickness , its fibers now held together by strong hydrogen bonds.
In a UMD Press releaseHuajian Gao, a professor at Brown University, described the technology as “a very promising path towards the design of lightweight, high-performance structural materials, with enormous potential for a wide range of applications where high strength, high toughness and superior ballistic resistance are desired.” The researchers predict the process will lead to the replacement of hardwoods in furniture and other applications with modified softwoods that grow faster and are more widely available.
Scientists from the KTH Royal Institute of Technology in Stockholm have performed similar lignin removal experiments on wood with other findings. Rather than seeking strength, they achieved optical transparency. Lignin is also responsible for staining wood and once removed, the material turns white. To amplify the substance’s light-transmitting abilities, Professor Lars Berglund of the Wallenberg Wood Science Center and his team impregnated the porous material with a transparent polymer. The result is a thin substrate reminiscent of plexiglass, which the researchers say could be a sustainable alternative to window glazing and the glass surface of photovoltaic panels. “Transparent wood is a good material for solar cells because it is an inexpensive, readily available and renewable resource,” Berglund said in the release. “No one had previously considered the possibility of creating larger, transparent structures for use as solar cells and in buildings.
Despite the many impressive innovations in wood materials, precautions remain. We need to improve monitoring of the timber chain of custody to prevent deforestation, biodiversity loss and other ecological degradation that can result from poor forest management. New hybrids like wood-concrete, especially when made with waste wood fibers, have a compelling case for the durability of the materials. Yet, care must always be taken when creating composites in which the original ingredients cannot be easily extracted for recycling, especially when the components come from both biological and engineered resources, a phenomenon ” Cradle to Cradle: Remaking the Way We Make Things” (North Point Press, 2002) authors William McDonough and Michael Braungart call “Frankenstein products.” For example, lignin is a rich carbon sink, with an energy content equivalent to that of coal, but manipulation of the cell can affect this carbon storage potential.
As part of responsible environmental practices, wood brings new capabilities that promise many positive transformations in the current and future built environment. As the AEC industry becomes increasingly carbon conscious, wood building products could lead to a sea change, replacing many non-renewable and energy-intensive substances with carbon-storing renewable biomass.