3D Printed Composite Bio-Walls for Sustainable Construction

Branch Technology is a construction technology firm specializing in large-scale 3D printing of construction wall systems using its patented and proprietary process, Cellular Fabrication (C-Fab«). C-Fab« combines industrial robotics, custom geometric sequencing algorithms, composite material science, and a novel Freeform 3D printing capability that enables printed material to solidify in free space without supports. This ultra-material-efficient digital manufacturing technique allows Branch to fabricate at construction scale while minimizing waste. Its products are composites made up of a Freeform 3D printed polymer lattice, an insulation injected into the lattice's interstitial spaces, and a surface-applied architectural finish. The infilling and finishing materials add functionality (like fire retardance, insulation, and water resistance) and reinforce and multiply the structural performance of the lattice, creating a multifunctional composite with an incredible strength-to-weight ratio. The company focuses on producing prefabricated wall systems for commercial construction with the Branch CompositeCore. While these product systems have high architectural design freedom and building performance characteristics, they are still largely produced with traditional, petroleum-derived materials. In this project, Branch proposes developing a 3D printed "BioWall" that is entirely produced with bio-derived materials. Each main constituent material is biologically based and has a viable path to sustainability, low or zero embodied carbon, and biodegradation for circularity (without compromising building performance and durability). Adopting this technology will help the US Army - which owns and operates more than 137,000 buildings ¢ with its goals of trying to reduce its carbon footprint by 50% over the next 6 years and attain net-zero carbon footprint by 2050. In Phase I, Branch proved the feasibility of a BioWall composition by investigating 49 different materials across the 3 constituent categories of the Branch CompositeCore and by performing manufacturability and structural testing with the top candidates. In this Phase II project, Branch will perform deeper analysis of the three most promising materials from Phase I ¢ a thermoplastic polymer called cellulose acetate, an infilling biomass made of mycelium and upcycled foam waste from BranchÆs existing process, and a bio-based cork spray finish lamina that has the added advantage of being sprayable. In addition to qualifying these 3 materials, Branch: will explore some additional promising material candidates, will perform analysis of both the DoD construction market and any construction precedents for biomaterials use, will perform printability enhancements to the companyÆs hardware stack tailored for unique properties of biopolymer printing, will select and perform large-scale building code compliance testing on the most viable composition, and will manufacture and install a prototype demonstration.