Researchers at the US Department of Energy’s Oak Ridge National Laboratory and the University of Maine have designed and 3D printed a one-piece, recyclable floor slab made from natural materials that has proven strong enough to replace building materials such as steel.
The project is part of the Sustainable Materials & Manufacturing Alliance for Renewable Technologies (SM2ART) program. Previously, the SM2ART team created BioHome3D, the first home in the US to be additively manufactured entirely from biological materials.
BioHome3D’s floor panel and other components were recently displayed during the U.S. Department of Housing and Urban Development’s Housing Innovation Showcase 2024 on the National Mall. The SM2ART Nfloor cassette is designed to replace traditional steel and concrete surfaces, representing a significant step forward for the construction of residential buildings. This technology could promote the use of sustainable, modular building sections.
Modular construction, in which complete building components are prefabricated in a factory and then delivered to the construction site for final assembly, is increasingly seen as a cost-effective way to develop sustainable housing structures in urban areas. ORNL researcher Katie Copenhaver explains that this first attempt to produce a strong floor slab from environmentally friendly resources significantly increases the potential for the use of organic materials in modular multi-family housing.
“By utilizing bio-based, large-scale 3D printing, we replaced an assembly made from 31 parts and three materials with a single-material floor panel that is ecologically friendly,” she said, “and with the same strength as traditional steel floor fabrication.”
The robustness of the SM2ART floor panel comes from the unique blend of polylactic acid (PLA) and wood flour, which is derived from wood processing waste.
“The PLA and wood flour blend is an excellent material for producing recyclable, large-format additively manufactured parts,” said Scott Tomlinson, structural engineer with the University of Maine’s Advanced Structures and Composites Center. “This single-piece floor assembly is stiffer and provides an improved walking experience when compared to the steel-concrete assembly it replaces.”
To create the floor slab, the researchers used a large-format 3D printer that layered the PLA/wood flour mixture into precise geometric shapes. The printing process took around 30 hours and resulted in a labor saving of around 33% compared to the manual production of a similar steel structure.
A significant cost factor with traditional steel frames arises from the subsequent insertion of ducts for electrical cables, piping and ventilation shafts.
“3D printing can save time and money by printing the floor cassette with cutouts designed into the finished product,” said Copenhaver. “The only human labor involves installing acoustic skin for sound proofing and the resident’s desired floor covering.”
The SM2ART floor panel is fully recyclable. Unlike building materials that end up in a landfill after a building is demolished, PLA, as a renewable material, can be reprocessed into new products after disassembly, contributing to a more sustainable circular economy.
“The next steps will be to make the manufacturing process faster, more efficient and cost-effective with additional functionality,” UMaine’s Tomlinson said. “This technology holds a lot of promise for the future of sustainable buildings.”
The project is in the early stages of development. Further research includes integrating flame retardants, sustainable insulation and improving production techniques.
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