By Ian Randall
A fire-retardant structural material can be made by chemically softening and compressing wood to remove the spaces between cell walls. When burnt, the resulting material forms a protective char layer on its outside which helps preserve its internal strength.
The use of wood in structural applications is limited by both its inherent flammability and susceptibility to rapid collapse on burning. Wood can be made more fire-proof by chemical treatments – such as through injections of halogenated flame retardants, or coatings of inorganic nanoparticles – but these approaches are typically either prohibitively expensive, fail environmental and health standards, or result in insufficient structural strength.
Liangbing Hu and colleagues of the University of Maryland in the US show that their process to create bullet-proof wood through densification also confers fire-resistant properties without recourse to potentially toxic or environmentally-unfriendly materials.
The densified material – which Hu dubs ‘super wood’ – is created by first chemically treating timber with sodium hydroxide and sodium sulfite to partially remove its lignin, the organic polymer which makes cell walls rigid. Subsequent hot pressing creates a dense, laminated material free of lumina – the tiny channels that create a porous structure, supplying oxygen and increasing flammability.
By Andrew Moore
The tiny rod-like structures have been shown to improve the strength and durability of concrete structures and reduce the carbon footprint of manufacturing cement.
If you were to walk through downtown Greenville, you would likely notice several landmarks, including the Liberty Bridge and the old county courthouse.
While these iconic structures are unique in their own right, they share one commonality: They’re made of concrete. The coarse, gray material is the very foundation of modern infrastructure. It’s been used in the construction of everything from buildings and bridges to roads and sidewalks.
But despite all its benefits of strength and durability, there’s a major downside to using concrete.
The production of cement, which when mixed with water forms the binding agent in concrete, accounts for 5 to 10 percent of all human-caused carbon dioxide emissions, according to the International Energy Agency. These emissions have been on the rise since the industrial revolution and remain the leading cause of global warming.
Over the past decade, though, researchers from across the country have been working together to create a cleaner version of the versatile building material. And now they plan to test the capabilities of their environmentally friendly alternative in Greenville.
The U.S. Endowment for Forestry and Communities, a Greenville-based environmental nonprofit, has partnered with the U.S. Forest Service, Oregon State University, and Purdue University to study a concrete mixture infused with cellulosic nanomaterials.
Cellulosic nanomaterials are produced by breaking down wood to its smallest, strongest components through mechanical and chemical processes similar to making paper. These tiny rodlike structures have diameters 20,000 times smaller than the width of a human hair and can be seen only using an electron microscope, yet they are as strong as steel with only one-fifth the weight.
“Researchers are testing these cellulosic nanomaterials in a wide range of applications from substrate for computer chips, they don’t warp under heat like plastics do, to car and airplane bodies, lighter and stronger than steel,” said Dr. Alan Rudie, a chemist with the U.S. Forest Service’s Forest Products Laboratory in Wisconsin, in a news release. “Our team expects that concrete will be among the first commercial applications.”
The shift from fossil-based industries to a bioeconomy is creating a growing demand for biobased chemicals, materials and fuels as sustainable and renewable alternatives. One possible source is fructose from wood for use in the production of bioplastics.
Lignocellulosic biomass is typically nonedible plant material, including dedicated crops of wood and grass, as well as waste material from agroforestry. It is also the single most abundant renewable resource on earth and available all year round. Furthermore, lignocellulosic biomass does not need valuable space in fields as it has no agricultural or nutritional use. It’s noteworthy, that wood can be harvested sustainably from certified forests. In the Nordic countries, more forest is grown than gets harvested each year.
Compared to other lignocellulosic feedstocks like straw, wood-based feedstocks for biorefinery have the greatest potential to replace fossil derived compounds in the chemical industry. Establishing competitive value chains based on lignocellulosic feedstock will not only secure an abundant alternative industrial feedstock but also strengthen the competitive position of biobased chemicals and materials compared to their fossil-based counterparts.
The EU-funded Horizon 2020 ReTAPP project investigated the production of fructose sugar using lignocellulosic biomass from hardwood and softwood feedstocks. “Researchers employed enzyme solutions to replace food/starch-based-fructose with wood derived fructose and prepared the entire value chain for launching the product onto the market,” says project coordinator Matti Heikkilä.
By George Plaven
Timm Locke relishes a chance to drive around Portland and showcase the latest commercial buildings made with mass timber, a construction material that uses wood beams and panels instead of concrete and steel.
First stop: Albina Yard, a four-story office building that opened in 2016 featuring cross-laminated timber panels from D.R. Johnson, a lumber company south of Roseburg.
Every piece of cross-laminated timber — or CLT for short — is prefabricated, designed for a specific part of the building, said Locke, director of forest products at the Oregon Forest Resources Institute. That means buildings go up faster, with fewer workers.
Wood is also environmentally superior to steel and concrete, Locke said, because it sequesters carbon and takes less energy to produce.
“There are so many benefits, it doesn’t matter which one you choose to start with,” Locke said.
First developed in Europe, mass timber is now catching on in the U.S., and Oregon is working to position itself as the industry hub, kick-starting rural economies that have traditionally relied on forest products. On Aug. 1, Oregon became the first state to approve language in its building codes allowing for wood-framed buildings up to 18 stories tall.
BY ADELE PETERS
Spinnova has found a way to spin any cellulose–wood, potato peels, even old T-shirts–into new, strong fiber.
In a new pilot factory in Jyväskylä, Finland–a city surrounded by forests and known in part for its lumber and paper industries–a startup will soon begin to turn wood pulp into something new: a type of fabric that could eventually compete with cotton.
Making wood into fabric isn’t new, but older wood-based fabrics like rayon use harsh chemicals that can pollute water and poison workers. The new fabric, made by a startup called Spinnova, uses a mechanical process instead of chemicals; the only byproduct is evaporated water, which is reused in production. Unlike cotton, which uses massive amounts of water in areas often prone to droughts, it needs little water, no pesticides, and no farmland.
The new process uses FSC-certified wood pulp that’s ground into a gel-like material called microfibrillated cellulose, which is made of tiny fibers. The material flows through the startup’s patented machinery to create a network of fibers that are spun and dried into a fluffy, firm wool that can be knit or woven into fabric and then made into clothing, shoes, or other textiles.
By Emily Pollock
M-Fire’s fire-inhibiting wood looks increasingly important in an industry turning back to wood buildings.
The phrase “wood buildings” conjures up images of flammable, unsafe architecture, but M-Fire Suppression Inc. is looking to change that picture. And it wants its fire-resistant wood to be the new face of ecologically friendly building.
One of the most common tests of a material’s fire resistance is a spread test, where inspectors measure how long it takes fire to spread across the material as compared to control materials. Class A is the most fire-resistant class, and M-Fire is currently the only company making Class A fire-protected cross-laminated timber. To do that, the company infuses wood with surfactants that allow fire inhibitors to migrate into the pockets of oxygen in the wood. The result is a product much eco-friendlier than most traditional fire inhibition. M-Fire is currently the only Class A fire inhibitor with UL Greenguard Gold certification, which means that it’s safe around children and schools.
“We don’t even like the name fire retardant near our brand. We’re a fire inhibitor,” said Steve Conboy, the company’s chairman and general manager. “What happens is, we inhibit fire because we break the chemical reaction in the fire.” The inhibitor breaks the chain of free radicals (H+, OH- and O-) released during combustion, giving the fire nothing to feed on.
The fire protection results in what Conboy calls “defended carbon”: carbon that is stored in the wood and will never be released into the atmosphere. A carbon-absorbing building material gives M-Fire’s wood a distinct advantage over carbon-producing alternatives like structural steel.
A consortium of timber and CLT companies have teamed up with the U.S. Army and Lendlease to test the blast capacity of timber structures in the real world, setting the stage for more mass timber buildings.
In the Microbial Sciences Building at the University of Wisconsin-Madison, the incredibly efficient eating habits of a fungus-cultivating termite are surprising even to those well acquainted with the insect’s natural gift for turning wood to dust.
According to a study published today (April 17, 2017) in the journal Proceedings of the National Academy of Sciences, when poplar wood undergoes a short, 3.5-hour transit through the gut of the termite, the emerging feces is almost devoid of lignin, the hard and abundant polymer that gives plant cells walls their sturdiness. As lignin is notorious for being difficult to degrade, and remains a costly obstacle for wood processing industries such as biofuels and paper, the termite is the keeper of a highly sought after secret: a natural system for fully breaking down biomass.
“The speed and efficiency with which the termite is breaking down the lignin polymer is totally unexpected,” says John Ralph, a UW-Madison professor of biochemistry, researcher at the Great Lakes Bioenergy Research Center (GLBRC) and lignin expert. “The tantalizing implication is that this gut system holds keys to breaking down lignin using processes that are completely unknown.”
To make biofuels, tiny microbes can be used to break down plant cells. As part of that digestive process, specialized enzymes break down cellulose—a major molecule that makes plant cell walls rigid. Scientists showed that an enzyme, from the bacterial glycoside hydrolase family 12, plays an unexpectedly important role in breaking down a hard-to-degrade crystalline form of cellulose. Surprisingly, the enzyme breaks apart the cellulose via a random mechanism unlike other hydrolases.
Breaking down cellulose is a major challenge in developing more efficient strategies for converting plant biomass to fuels and chemicals. The discovery of a specialized enzyme that is highly effective at breaking down rigid plant cell wall components could be harnessed to solve this challenge.
By Gillian Flaccus and Phuong Lee / The Associated Press
RIDDLE — John Redfield watches with pride as his son moves a laser-guided precision saw the size of a semi-truck wheel into place over a massive panel of wood.
Redfield’s fingers are scarred from a lifetime of cutting wood and now, after decades of decline in the logging business, he has new hope that his son, too, can make a career shaping the timber felled in Southern Oregon’s forests.
That’s because Redfield and his son work at D.R. Johnson Lumber Co., one of two U.S. timber mills making a new wood product that’s the buzz of the construction industry. It’s called cross-laminated timber, or CLT, and it’s made like it sounds: rafts of 2-by-4 beams aligned in perpendicular layers, then glued — or laminated — together like a giant sandwich.
The resulting panels are lighter and less energy-intensive than concrete and steel and much faster to assemble on-site than regular timber, proponents say. Because the grain in each layer is at a right angle to the one below and above it, there’s a counter-tension built into the panels that supporters say makes them strong enough to build even the tallest skyscrapers.
“We believe that two to five years out, down the road, we could be seeing this grow from just 20 percent of our business to potentially 60 percent of our business,” said Redfield, D.R. Johnson’s chief operating officer. “We’re seeing some major growth factors.”
From Maine to Arkansas to the Pacific Northwest, the material is sparking interest among architects, engineers and researchers. Many say it could infuse struggling forest communities like Riddle with new economic growth while reducing the carbon footprint of urban construction with a renewable building material.