A research team at the University of Tennessee is developing a method to turn discarded wood waste into a material as strong as steel—using a process that could reshape how we think about sustainable construction.
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Led by Art Ragauskas, UT–ORNL Governor’s Chair for Biorefining and acting department head of Chemical and Biomolecular Engineering, the project—Waste Upcycling for Defense (WUD)—has received a $2 million contract from the Defense Advanced Research Projects Agency (DARPA).
UT is the lead institution, working in collaboration with the University of California, Riverside, and Georgia Tech.
Wood is low-cost and more environmentally friendly than metals and alloys, but its natural form doesn’t offer the mechanical strength required for structural use. Previous research has shown that when wood is densified—by removing lignin, the component that binds wood cells together, and compressing the structure—it can become significantly stronger.
Lignin forms a very stiff matrix with hemicellulose to protect the cellulose. It basically supports the plant, so once we remove that, that leaves a lot of space in the wood or in the cell wall. At that point, the cell wall is basically composed of cellulose and can be densified when compressed. The fibers form hydrogens bond that will provide additional strength to the material.
Yunxuan Wang, Post-Doctoral Researcher and Project Assistant, University of Tennessee
The process becomes more complex when dealing with mixed wood waste, such as scrap wood, paper, and cardboard.
“You don’t always have large chunks of wood available. You usually have a lot of waste wood during the manufacturing of wood, like the sawdust or those waste materials. So, the goal of the project is to utilize this material, but to achieve the same goal to make this densified board with very high strength,” said Wang.
This research responds to a broader need for sustainable alternatives to metal, which is energy-intensive to produce. A strengthened wood-based material could have applications in automotive, aerospace, and building construction.
Densified wood has historical precedent—in the 1930s, it was used as a metal substitute in military aircraft in the US and Germany.
“The conversion of waste wood to a high-performance board provides a unique opportunity to turn ‘trash to cash,’ minimize landfill needs, and reduce the logistics of building materials, especially in remote areas,” said Raguaskas.