M. Maughan, A. McDonald, A. Lehman-Chong
University of Idaho, Idaho, United States
Keywords: additive manufacturing, composites, biomass
Wood composite additive manufacturing (WCAM) uses indigenous natural wood fibers and/or locally available wood waste to replace concrete in on-demand physical infrastructure construction applications. Our system mitigates issues with concrete additive manufacturing (AM), specifically that concrete is difficult to transport, has a high embodied energy and limited renewability, and requires long curing times of 28 days. Our technology enables continuous mixing and deposition of cold-setting organic and inorganic thermoset wood composites with over 50% wood content. We have 3D printed a cold-setting sodium silicate (SS) binder with 50% wood, investigated how rheological behavior governs extrudate quality, examined cure behavior at ambient conditions and accelerated temperatures, and demonstrated that minimally processed wood flour with a nontoxic “geopolymer” binder results in AM wood composites that are fire resistant with mechanical properties rivaling AM concrete. WCAM expands AM construction capabilities, reduces logistics and supply chain impacts, mitigates construction waste, and produces adaptable structures that can adhere to existing building codes. WCAM mitigates CO2 emissions, requires lower processing energy, and upcycles wood waste to valorize these locally sourced materials. Additionally, our system can manufacture a variety of high-solid loading formulations, accommodating performance needs for both civilian and military construction applications.