|Compressive strength||39–75.7 N/mm2 (MPa)|
|Young's modulus||21.4 kN/m2|
|Temperature coefficient||5.4 × 10−6 K−1|
Lunarcrete, also known as "mooncrete", an idea first proposed by Larry A. Beyer of the University of Pittsburgh in 1985, is a hypothetical aggregate building material, similar to concrete, formed from lunar regolith, that would cut the construction costs of building on the Moon.
Only comparatively small amounts of moon rock have been transported to Earth, so in 1988 researchers at the University of North Dakota proposed simulating the construction of such a material by using lignite coal ash. Other researchers have used the subsequently developed lunar regolith simulant materials, such as JSC-1 (developed in 1994 and as used by Toutanji et al.). Some small-scale testing, with actual regolith, has been performed in laboratories, however.
The basic ingredients for lunarcrete would be the same as those for terrestrial concrete: aggregate, water, and cement. In the case of lunarcrete, the aggregate would be lunar regolith. The cement would be manufactured by beneficiating lunar rock that had a high calcium content. Water would either be supplied from off the moon, or by combining oxygen with hydrogen produced from lunar soil.
Lin et al. used 40g of the lunar regolith samples obtained by Apollo 16 to produce lunarcrete in 1986. The lunarcrete was cured by using steam on a dry aggregate/cement mixture. Lin proposed that the water for such steam could be produced by mixing hydrogen with lunar ilmenite at 800°C, to produce titanium oxide, iron, and water. It was capable of withstanding compressive pressures of 75 MPa, and lost only 20% of that strength after repeated exposure to vacuum.
In 2008, Houssam Toutanji, of the University of Alabama in Huntsville, and Richard Grugel, of the Marshall Space Flight Center, used a lunar soil simulant to determine whether lunarcrete could be made without water, using sulfur (obtainable from lunar dust) as the binding agent. The process to create this sulfur concrete required heating the sulfur to 130–140°C. After exposure to 50 cycles of temperature changes, from -27°C to room temperature, the simulant lunarcrete was found to be capable of withstanding compressive pressures of 17MPa, which Toutanji and Grugel believed could be raised to 20MPa if the material were reinforced with silica (also obtainable from lunar dust).
Casting and production
There would need to be significant infrastructure in place before industrial scale production of lunarcrete could be possible.
The casting of lunarcrete would require a pressurized environment, because attempting to cast in a vacuum would simply result in the water, required for the chemical reaction that forms the curing process, evaporating, and the lunarcrete failing to harden. Two solutions to this problem have been proposed: premixing the aggregate and the cement and then using a steam injection process to add the water, or the use of a pressurized concrete fabrication plant that produces pre-cast concrete blocks.
Lunarcrete shares the same lack of tensile strength as terrestrial concrete. One suggested lunar equivalent tensioning material for creating pre-stressed concrete is lunar glass, also formed from regolith, much as fibreglass is already sometimes used as a terrestrial concrete reinforcement material. Another tensioning material, suggested by David Bennett, is Kevlar, imported from Earth (which would be cheaper, in terms of mass, to import from Earth than conventional steel).
David Bennett, of the British Cement Association, argues that lunarcrete has the following advantages as a construction material for lunar bases:
- Lunarcrete production would require less energy than lunar production of steel, aluminium, or brick.
- It is unaffected by temperature variations of +120°C to −150°C.
- It will absorb gamma rays.
- Material integrity is not affected by prolonged exposure to vacuum. Although free water will evaporate from the material, the water that is chemically bound as a result of the curing process will not.
Bennett suggests that hypothetical lunar buildings made of lunarcrete would most likely use a low-grade concrete block for interior compartments and rooms, and a high-grade Dense Silica Particle cement-based concrete for exterior skins.
- J. A. Happel (1993). "Indigenous materials for lunar construction". Applied Mechanics Reviews (American Society of Mechanical Engineers) 46 (6): 313–325. Bibcode:1993ApMRv..46..313H. doi:10.1115/1.3120360.
- F. Ruess, J. Schaenzlin, and H. Benaroya (July 2006). "Structural Design of a Lunar Habitat" (PDF). Journal of Aerospace Engineering (American Society of Civil Engineers) 19 (3): 138. doi:10.1061/(ASCE)0893-1321(2006)19:3(133).
- "UND Engineers Would Like to Follow the Lunarcrete Road". Grand Forks Herald (North Dakota). 1988-02-28.
- H. Toutanji, M. R. Fiske, and M. P. Bodiford (2006). "Development and Application of Lunar ”Concrete” for Habitats". In Ramesh B. Malla, Wieslaw K. Binienda, and Arup K. Maji. Proceedings of 10th Biennial International Conference on Engineering, Construction, and Operations in Challenging Environments (Earth & Space 2006) and 2nd NASA/ARO/ASCE Workshop on Granular Materials in Lunar and Martian Exploration held in League City/Houston, TX, during March 5–8, 2006. Reston, VA: American Society of Civil Engineers. pp. 1–8. doi:10.1061/40830(188)69. ISBN 0784408300.
- François Spiero and David C. Dunand (1997). "Simulation of Martian Materials and Resources Exploitation on a Variable Gravity Research Facility". In Thomas R. Meyer. The Case for Mars IV: the international exploration of Mars — consideration for sending humans : proceedings of the fourth Case for Mars Conference held June 4–8, 1990, at the University of Colorado, Boulder, Colorado 90. Univelt for the American Astronautical Society. p. 356. ISBN 9780877034216.
- George William Herbert (1992-11-17). "Luna concrete". In Norman Yarvin. Archives: Space: Science, Exploration.
- Colin Barras (2008-10-17). "Astronauts Could Mix DIY Concrete for Cheap Moon Base". New Scientist.
- D. F. H. Bennett (2002). "Concrete: the material — Lunar concrete". Innovations in concrete. Thomas Telford Books. pp. 86–88. ISBN 0-7277-2005-8.
- Larry A. Beyer (October 1985). "Lunarcrete — A Novel Approach to Extraterrestrial Construction". In Barbara Faughnan and Gregg Maryniak. Space Manufacturing 5: Engineering with Lunar and Asterodial Materials, Proceedings of the Seventh Princeton/AIAA/SSI Conference May 8–11, 1985. American Institute of Aeronautics and Astronautics. p. 172. ISBN 093040307X ISBN 978-0-930403-07-2.
- T. D. Lin, H. Love, D. and Stark (October 1987). "Physical Properties of Concrete Made with Apollo 16 Lunar Soil Sample" (PDF). In Barbara Faughnan and Gregg Maryniak. Space Manufacturing 6: Proceedings of the Eighth Princeton/AIAA/SSI Conference May 6–9, 1987. American Institute of Aeronautics and Astronautics. pp. 361–366.
- N. Ishikawa, H. Kanamori, and T. Okada. "The Possibility of Concrete Production on the Moon" (PDF). In W. W. Mendell, J. W. Alred, L. S. Bell, M. J. Cintala, T. M. Crabb, and R. H. Durrett. The Second Conference on Lunar Bases and Space Activities of the 21st Century, Houston, TX, 5–7 Apr. 1988. NASA Conference Publication. pp. 489–492.
- R. Robinson (January 1989). "Building on the moon". Civil Engineering: 40–43.
- H. Kinomere, S. Matsumoto, H. Fujishiro, and K. Yatsuyanagi (1990). "A Cost Study of Concrete Production on the Moon". In Stewart W. Johnson and John P. Wetzel. Engineering, construction, and operations in space II: Space '90; Proceedings of the 2nd International Conference, Albuquerque, New Mexico, April 22–26, 1990. New York: American Society of Civil Engineers. pp. 1523–1532. ISBN 0872627527.
- Richard A. Kaden, ed. (1991). Lunar concrete: papers presented at the Lunar Technical Symposium, American Concrete Institute Committee 125, American Concrete Institute Annual Convention March 17–22, 1991. American Concrete Institute. ISBN 9789991045092.
- Dennis M. Pakulski and Kenneth J. Knox (1992). "Steam Injection System for Lunar Concrete". Engineering, construction, and operations in space III: Space '92; Proceedings of the 3rd International Conference, Denver, CO, May 31–June 4, 1992. 2 (A93-41976 17-12). pp. 1347–1358.
- T. D. Lin and Nan Su (1992). "Concrete Construction on the Moon". Engineering, construction, and operations in space III: Space '92; Proceedings of the 3rd International Conference, Denver, CO, May 31–June 4, 1992. 2 (A93-41976 17-12). pp. 1359–1369.
- Richard M. Drake (1992). "Design Concepts for a Lunar Concrete Production Facility". Engineering, construction, and operations in space III: Space '92; Proceedings of the 3rd International Conference, Denver, CO, May 31-–June 4, 1992. 2 (A93-41976 17-12). pp. 34–42.
- Husam Omar and Mohsen Issa (1993). "Cost Effectiveness of Lunar Concrete for Lunar Structures". Pacific International Conference on Aerospace Science and Technology, Taiwan, Republic of China, December 6–9, 1993.
- Husam A. Omar and Mohsen Issa (1994). "Feasibility of dual technology in manufacturing lunar concrete". In Rodney G. Galloway and Stanley Lokaj. Engineering, construction, and operations in space IV: Space '94; Proceedings of the 4th International Conference, Albuquerque, New Mexico, February 26–March 3, 1994 2. New York: American Society of Civil Engineers. pp. 933–941. ISBN 0872629376.
- Husam A. Omar and Mohsen Issa (1994). "Production of Lunar Concrete Using Molten Sulfur" (PDF). In Rodney G. Galloway and Stanley Lokaj. Engineering, construction, and operations in space IV: Space '94; Proceedings of the 4th International Conference, Albuquerque, New Mexico, February 26–March 3, 1994 2. New York: American Society of Civil Engineers. pp. 952–959. ISBN 0872629376.
- I. Casanova (1997). "Feasibility and Applications of Sulfur Concrete for Lunar Base Development: A Preliminary Study" (PDF). 28th Annual Lunar and Planetary Science Conference, March 17–21, 1997, Houston, TX. p. 209.
- T. D. Lin, Steven B. Skaar, and Joseph J. O'Gallagher (April 1997). "Proposed remote control solar powered concrete production experiment on the Moon". Aerospace Engineering 10 (2): 104–109.
- Houssam Toutanji, Becca Glenn-Loper, and Beth Schrayshuen (2005). "Strength and Durability Performance of Waterless Lunar Concrete" (PDF). 43rd AIAA Aerospace Sciences Meeting and Exhibit 10 – 13 January 2005, Reno, Nevada. American Institute of Aeronautics and Astronautics.
- R.N. Grugel, and Houssam Toutanji (2006). "Viability of Sulfur "Concrete" on the Moon: Environmental Consideration". Proceedings: 43rd American Institute of Aeronautics and Astronautics (AIAA), Reno, NV, Jan. 9-12, 2006. — also:
- R. Grugel, and Houssam Toutanji (2006). "Viability of Sulfur Concrete on the Moon: Environmental Considerations". Journal of Advances in Space Research.
- E.C. Ethridge, D.S. Tucker, and Houssam Toutanji (2006). "Production of Glass Fibers for Reinforcement of Lunar Concrete". 44th American Institute of Aeronautics and Astronautics (AIAA) Conference, Reno, NV, January 9–12, 2006.
- Richard N. Grugela and Houssam Toutanji (2008). "Sulfur "concrete" for lunar applications — Sublimation concerns". Advances in Space Research 41 (1): 103–112. Bibcode:2008AdSpR..41..103G. doi:10.1016/j.asr.2007.08.018.