The Role of Multi-Scale Porosity on Termite Mound Behavior

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Termite mounds provide an excellent example of naturally-built habitats that are efficient and resilient. Mound construction is achieved through efficient use of local materials without the need for a heat-beat-treat cycle often employed in the development of man-made materials. The mounds are also nature's model for combined structural and mechanical systems providing ventilation and temperature regulation solely through the form of the structure. An understanding of the natural processes involved in termite mound construction and function can be adapted to inform engineering applications related to the construction of man-made structures that require zero or minimal energy inputs. Also, as termites micro-3D-print mounds, this work can inform new paradigms in 3D-printed human structures. The transdisciplinary project will lead to advances in materials and structural forms that are informed by the construction methods of termites for structures that require significantly less energy and are more sustainable than traditional construction. Research outcomes will move the U.S. toward greater energy independence and security. Technology transfer of new materials and systems will grow manufacturing and strengthen national economic development. The overall goal of the project is to inform new processes for sustainable bio-inspired building systems and bio-cemented materials using locally available materials. This will be accomplished by identifying the thermal and mechanical properties of termite mounds as systems and the chemical, thermal and mechanical properties of the bio-cemented soil using the multi-scale porosity of the structure and material as the key parameter. The complex nano-to-mega-scale structure of the termite mounds will be analyzed using a suite of advanced techniques. 3D models of the macro-to-mega-scale pore structure of termite mounds will be developed by photogrammetric mapping their exterior and by imaging slices of cast molds of the interior tunnel structure. The nano-to-meso-scale pore structure of harvested bio-cemented material will be measured using nitrogen adsorption, mercury intrusion porosimetry, and high-resolution X-ray micro-computed tomography. Including porosity in consideration of homeostasis of termite mounds provides information on the importance of material properties in mound ventilation, thermal and structural characteristics. Studying the ability of termites to regulate systems through the synergy of the structural topology and unique materials can be a starting point for engineering designers to use local materials efficiently and adaptively.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.