"Submillimetre mechanistic designs of termite-built structures"

Oberst, S; Martin, R; Halkon, B; Lai, J; Evans, T; Saadatfar, M

"Submillimetre mechanistic designs of termite-built structures"

Oberst, S

Martin, R Halkon, B

Lai, J Evans, T Saadatfar, M

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Publisher:: The Royal Society
Publication Type:: Journal Article
Citation:: Journal of the Royal Society Interface, 2021, 18, (178), pp. 1-10
Issue Date:: 2021-05-05

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Field	Value	Language
dc.contributor.author	Oberst, S https://orcid.org/0000-0002-1388-2749
dc.contributor.author	Martin, R
dc.contributor.author	Halkon, B https://orcid.org/0000-0001-5459-2329
dc.contributor.author	Lai, J
dc.contributor.author	Evans, T
dc.contributor.author	Saadatfar, M
dc.date.accessioned	2022-03-01T04:26:48Z
dc.date.available	2022-03-01T04:26:48Z
dc.date.issued	2021-05-05
dc.identifier.citation	Journal of the Royal Society Interface, 2021, 18, (178), pp. 1-10
dc.identifier.issn	1742-5662
dc.identifier.issn	1742-5689
dc.identifier.uri	http://hdl.handle.net/10453/154935
dc.description.abstract	Termites inhabit complex underground mounds of intricate stigmergic labyrinthine designs with multiple functions as nursery, food storage and refuge, while maintaining a homeostatic microclimate. Past research studied termite building activities rather than the actual material structure. Yet, prior to understanding how multi-functionality shaped termite building, a thorough grasp of submillimetre mechanistic architecture of mounds is required. Here, we identify for Nasutitermes exitiosus via granulometry and Fourier transform infrared spectroscopy analysis, preferential particle sizes related to coarse silts and unknown mixtures of organic/inorganic components. High-resolution micro-computed X-ray tomography and microindentation tests reveal wall patterns of filigree laminated layers and sub-millimetre porosity wrapped around a coarse-grained inner scaffold. The scaffold geometry, which is designed of a lignin-based composite and densely biocementitious stercoral mortar, resembles that of trabecula cancellous bones. Fractal dimension estimates indicate multi-scaled porosity, important for enhanced evaporative cooling and structural stability. The indentation moduli increase from the outer to the inner wall parts to values higher than those found in loose clays and which exceed locally the properties of anthropogenic cementitious materials. Termites engineer intricately layered biocementitious composites of high elasticity. The multiple-scales and porosity of the structure indicate a potential to pioneer bio-architected lightweight and high-strength materials.
dc.format	Print-Electronic
dc.language	eng
dc.publisher	The Royal Society
dc.relation	http://purl.org/au-research/grants/arc/DP200100358
dc.relation.ispartof	Journal of the Royal Society Interface
dc.relation.isbasedon	10.1098/rsif.2020.0957
dc.rights	info:eu-repo/semantics/closedAccess
dc.subject.classification	General Science & Technology
dc.subject.mesh	Animals
dc.subject.mesh	Isoptera
dc.subject.mesh	Porosity
dc.subject.mesh	Spectroscopy, Fourier Transform Infrared
dc.subject.mesh	Animals
dc.subject.mesh	Isoptera
dc.subject.mesh	Spectroscopy, Fourier Transform Infrared
dc.subject.mesh	Porosity
dc.title	"Submillimetre mechanistic designs of termite-built structures"
dc.type	Journal Article
utslib.citation.volume	18
utslib.location.activity	England
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology/School of Mechanical and Mechatronic Engineering
utslib.copyright.status	closed_access	*
pubs.consider-herdc	true
dc.date.updated	2022-03-01T04:26:47Z
pubs.issue	178
pubs.publication-status	Published
pubs.volume	18
utslib.citation.issue	178

Abstract:

Termites inhabit complex underground mounds of intricate stigmergic labyrinthine designs with multiple functions as nursery, food storage and refuge, while maintaining a homeostatic microclimate. Past research studied termite building activities rather than the actual material structure. Yet, prior to understanding how multi-functionality shaped termite building, a thorough grasp of submillimetre mechanistic architecture of mounds is required. Here, we identify for Nasutitermes exitiosus via granulometry and Fourier transform infrared spectroscopy analysis, preferential particle sizes related to coarse silts and unknown mixtures of organic/inorganic components. High-resolution micro-computed X-ray tomography and microindentation tests reveal wall patterns of filigree laminated layers and sub-millimetre porosity wrapped around a coarse-grained inner scaffold. The scaffold geometry, which is designed of a lignin-based composite and densely biocementitious stercoral mortar, resembles that of trabecula cancellous bones. Fractal dimension estimates indicate multi-scaled porosity, important for enhanced evaporative cooling and structural stability. The indentation moduli increase from the outer to the inner wall parts to values higher than those found in loose clays and which exceed locally the properties of anthropogenic cementitious materials. Termites engineer intricately layered biocementitious composites of high elasticity. The multiple-scales and porosity of the structure indicate a potential to pioneer bio-architected lightweight and high-strength materials.

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http://hdl.handle.net/10453/154935