Basalt fibre reinforced geopolymer
Human missions to the lunar surface might require the capability to build structures on site using the moon’s natural resources as a potentially more economically viable alternative to transporting all materials needed for the construction of an outpost from Earth to the lunar surface. In-situ resource utilization (ISRU) might therefore be necessary to provide – apart from other resources – material to construct radiation shields, habitat walls/shells and infrastructure like landing pads, surface paving and dust-shield walls. Concrete and ceramic materials can be (mostly) made from lunar regolith. They would be able to improve protection of the crew from harsh environmental conditions like solar wind, radiation and micrometeorites and extreme thermal cycling (between -173°C and +117°C). Those materials need either a chemical binder containing water (consumable resources) or comparatively larger amounts of energy. Construction materials that use little of those resources while providing sufficient protection against the harsh lunar environment are therefore of interest.
Geopolymer is a fire- and heat resistant inorganic polymer. It develops, when a polymeric reaction between an alkaline solution and an aluminosilica rich precursor takes place (Davidovits et al., 1990). Lunar regolith is made up in large parts of silicon and aluminium oxides. Fly ash, which is a precursor that is used on Earth to produce geopolymers, closely resembles the oxide and phase composition of lunar regolith (Table 1). Geopolymer therefore is a promising ISRU construction material for the lunar surface and might be well suited to build shielding structures against ionizing radiation (Montes et al., 2015).
Basalt fibres are a material that could be produced in situ at the lunar surface (Pico et al., 2017) and could increase the structural properties of geopolymer. They have been used as a reinforcement phase to geopolymers in terrestrial applications, exhibiting enhancements in mechanical strength compared with pure geopolymers.
This Ariadna study is conducted in collaboration with our partners at the Advanced Materials Group of Prof. Anna-Lena Kjøniksen at Østfold University College. The aim is to investigate the structural performance and shielding abilities of lunar regolith simulant based, basalt fibre reinforced geopolymer when cured under simulated environmental conditions (temperature and vacuum) of the lunar surface. The prepared composites will be evaluated for their mechanical and radiation shielding properties and will undergo Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) analysis and X-ray tomography for concept validation. Furthermore, the compatibility of geopolymer for the use with extrusion 3D-printing processes for construction on the lunar surface will be assessed. The study will investigate the combination of material and construction technique towards its resource efficiency and applicability for lunar surface applications.
References
- Davidovits J., Comrie D., Paterson J.H., Ritcey D.J.. 1990. Geopolymeric concretes for environmental protection. ACI Concr. Int., 12 (1990), p. 3040
- Haskin L.A., Warren P.H.. 1991. Lunar chemistry. G.H. Heiken, D.T. Vaniman, B.M. French (Eds.), Lunar Sourcebook, Cambridge University Press, New York (1991), pp. 367-474
- Aughenbaugh Katherine L., Stutzman Paul, Juenger Maria C. G. 2016. Identifying Glass Compositions in Fly Ash. Frontiers in Materials. Volume 3, 2016. ISSN: 2296-8016.
- Montes C., Broussard K., Gongre M., Simicevic N., Mejia J., Tham J., Allouche E., Davis G.. 2015-09-15. Evaluation of lunar regolith geopolymer binder as a radioactive shielding material for space exploration applications. Advances in Space Research 56/6 (2015), 1212-1221. Elsevier. https://doi.org/10.1016/j.asr.2015.05.044.
- Pico D., Lüking A., Blay Sempere A., Gries T.. 2017. Moon Basalt Fiber - preliminary feasibility study. Institut für Textiltechnik der RWTH Aachen University.