View source for Lunarcrete

{| class="infobox" style="width: 250px; text-align: left; float:right; font-size: 88%;"
|+ style="font-weight: bold; font-size: 125%;" | Laboratory-determined properties for lunarcrete<ref>{{cite journal|author=J. A. Happel|date=1993|title=Indigenous materials for lunar construction|journal=Applied Mechanics Reviews|doi=10.1115/1.3120360|volume=46|issue=6|pages=313&ndash;325|publisher=[[American Society of Mechanical Engineers]]}}</ref><ref name=Ruess />
|-
! [[Compressive strength]]
| 39&ndash;75.7 N/mm<sup>2</sup> ([[Pascal (unit)|MPa]])
|-
! [[Young's modulus]]
| 21.4&nbsp;kN/m<sup>2</sup>
|-
! [[Density]]
| 2.6 g/cm<sup>3</sup>
|-
! [[Temperature coefficient]]
| 5.4 &times; 10<sup>−6</sup> K<sup>−1</sup>
|}
'''Lunarcrete''', also known as "'''Mooncrete'''", an idea first proposed by Larry A. Beyer of the [[University of Pittsburgh]] in 1985 (see [[#Further reading|further reading]]), is a hypothetical aggregate building material, similar to [[concrete]], formed from lunar [[regolith]], that would cut the construction costs of building on the [[moon]].<ref name=GFH>{{cite news|work=[[Grand Forks Herald]]|location=North Dakota|date=1988-02-28|title=UND Engineers Would Like to Follow the Lunarcrete Road}}</ref>  

== Ingredients ==
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]] [[coal ash|ash]].<ref name=GFH />  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.).<ref>{{cite conference|title=Development and Application of Lunar ”Concrete” for Habitats|author=H. Toutanji, M. R. Fiske, and M. P. Bodiford|pages=1&ndash;8|doi=10.1061/40830(188)69|booktitle=Proceedings of 10th Biennial International Conference on Engineering, Construction, and Operations in Challenging Environments (Earth &amp; 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&ndash;8, 2006|editor=Ramesh B. Malla, Wieslaw K. Binienda, and Arup K. Maji|location=Reston, VA|publisher=[[American Society of Civil Engineers]]|id=ISBN 0784408300|date=2006}}</ref>  Some small-scale testing, with actual regolith, has been performed in laboratories, however.<ref name=Ruess>{{cite journal|url=http://coewww.rutgers.edu/~benaroya/publications/Ruess%20et%20al%20ASCE%20JAE.pdf|format=PDF|journal=Journal of Aerospace Engineering|publisher=[[American Society of Civil Engineers]]|date=July 2006|pages=138|title=Structural Design of a Lunar Habitat|author=F. Ruess, J. Schaenzlin, and H. Benaroya|doi=10.1061/(ASCE)0893-1321(2006)19:3(133)|volume=19|issue=3}}</ref>

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 [[beneficiation|beneficiat]]ing 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]].<ref name=Ruess />

Lin et al. used 40g of the lunar regolith samples obtained by [[Apollo 16]] to produce Lunarcrete in 1986 (see [[#Further reading|further reading]]).<ref>{{cite conference|title=Simulation of Martian Materials and Resources Exploitation on a Variable Gravity Research Facility|author=François Spiero and David C. Dunand|booktitle=The Case for Mars IV: the international exploration of Mars &mdash; consideration for sending humans : proceedings of the fourth Case for Mars Conference held June 4&ndash;8, 1990, at the University of Colorado, Boulder, Colorado|editor=Thomas R. Meyer|publisher=Univelt for the [[American Astronautical Society]]|date=1997|isbn=0877034214|isbn13=9780877034216|volume=90|pages=356}}</ref>  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.<ref>{{cite web|url=http://yarchive.net/space/science/lunar_concrete.html|title=Luna concrete|author=George William Herbert|date=1992-11-17|editor=Norman Yarvin|work=Archives: Space: Science, Exploration}}</ref>

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 [[sulphur]] (obtainable from lunar dust) as the binding agent.  The process required heating the sulphur to 130&ndash;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).<ref>{{cite news|title=Astronauts Could Mix DIY Concrete for Cheap Moon Base|work=[[New Scientist]]|author=Colin Barras|date=2008-10-17|url=http://newscientist.com/article/dn14977}}</ref>

== Casting and production ==
There would need to be significant infrastructure in place before industrial scale production of lunarcrete could be possible.<ref name=Ruess />

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 [[concrete curing|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.<ref name=Ruess /><ref name=Bennett />

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.<ref name=Ruess /> 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).<ref name=Bennett />

== Use ==
David Bennett, of the British Cement Association, argues that Lunarcrete has the following advantages as a construction material for lunar bases:<ref name=Bennett>{{cite book|title=Innovations in concrete|author=D. F. H. Bennett|pages=86&ndash;88|date=2002|publisher=Thomas Telford Books|isbn=0727720058|chapter=Concrete: the material &mdash; Lunar concrete}}</ref>
* Lunarcrete production would require less energy than lunar production of [[steel]], [[aluminium]], or [[brick]].<ref name=Bennett />
* It is unaffected by temperature variations of +120°C to &minus;150°C.<ref name=Bennett />
* It will absorb [[gamma ray]]s.<ref name=Bennett />
* 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.<ref name=Bennett />
He observes, however, that Lunarcrete is not an airtight material, and to make it airtight would require the application of an [[epoxy]] coating to the interior of any Lunarcrete structure.<ref name=Bennett />

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.<ref name=Bennett />

== References ==
{{reflist}}

== Further reading ==
* {{cite conference|title=Lunarcrete &mdash; A Novel Approach to Extraterrestrial Construction|author=Larry A. Beyer|pages=172|booktitle=Space Manufacturing 5: Engineering with Lunar and Asterodial Materials, Proceedings of the Seventh Princeton/AIAA/SSI Conference May 8&ndash;11, 1985|editor=Barbara Faughnan and Gregg Maryniak|date=October 1985|publisher=[[American Institute of Aeronautics and Astronautics]]|id=ISBN 093040307X ISBN 9780930403072|url=http://spacestudiesinstitute.wordpress.com/1985/12/}}
* {{cite conference|author=T. D. Lin, H. Love, D. and Stark|title=Physical Properties of Concrete Made with Apollo 16 Lunar Soil Sample|booktitle=Space Manufacturing 6: Proceedings of the Eighth Princeton/AIAA/SSI Conference May 6&ndash;9, 1987|editor=Barbara Faughnan and Gregg Maryniak|publisher=[[American Institute of Aeronautics and Astronautics]]|date=October 1987|url=http://www.nss.org/settlement/moon/library/LB2-515-ConcreteMadeFromApollo16sample.pdf|format=PDF|pages=361&ndash;366}}
* {{cite conference|booktitle=The Second Conference on Lunar Bases and Space Activities of the 21st Century, Houston, TX, 5&ndash;7 Apr. 1988|editor=W. W. Mendell, J. W. Alred, L. S. Bell, M. J. Cintala, T. M. Crabb, and R. H. Durrett|url=http://www.nss.org/settlement/moon/library/LB2-516-ConcreteProductionOnTheMoon.pdf|format=PDF|title=The Possibility of Concrete Production on the Moon|author=N. Ishikawa, H. Kanamori, and T. Okada|pages=489&ndash;492|publisher=NASA Conference Publication}}
* {{cite journal|author=R. Robinson|date=January 1989|title=Building on the moon|journal=Civil Engineering|pages=40&ndash;43}}
* {{cite conference|author=H. Kinomere, S. Matsumoto, H. Fujishiro, and K. Yatsuyanagi|title=A Cost Study of Concrete Production on the Moon|booktitle=Engineering, construction, and operations in space II: Space '90; Proceedings of the 2nd International Conference, Albuquerque, New Mexico, April 22&ndash;26, 1990|pages=1523&ndash;1532|editor=Stewart W. Johnson and John P. Wetzel|location=New York|publisher=[[American Society of Civil Engineers]]|id=ISBN 0872627527|date=1990}}
* {{cite book|title=Lunar concrete: papers presented at the Lunar Technical Symposium, American Concrete Institute Committee 125, American Concrete Institute Annual Convention March 17&ndash;22, 1991|editor=Richard A. Kaden|publisher=American Concrete Institute|date=1991|url=http://www.normas.com/ACI/PAGES/SP-125.html|isbn=9991045090|isbn13=9789991045092}}
* {{cite conference|title=Steam Injection System for Lunar Concrete|author=Dennis M. Pakulski and Kenneth J. Knox|pages=1347&ndash;1358|booktitle=Engineering, construction, and operations in space III: Space '92; Proceedings of the 3rd International Conference, Denver, CO, May 31&ndash;June 4, 1992|volume=2 (A93-41976 17-12)|date=1992}}
* {{cite conference|title=Concrete Construction on the Moon|author=T. D. Lin and Nan Su|pages=1359&ndash;1369|booktitle=Engineering, construction, and operations in space III: Space '92; Proceedings of the 3rd International Conference, Denver, CO, May 31&ndash;June 4, 1992|volume=2 (A93-41976 17-12)|date=1992}}
* {{cite conference|title=Design Concepts for a Lunar Concrete Production Facility|author=Richard M. Drake|pages=34&ndash;42|booktitle=Engineering, construction, and operations in space III: Space '92; Proceedings of the 3rd International Conference, Denver, CO, May 31-&ndash;June 4, 1992|volume=2 (A93-41976 17-12)|date=1992}}
* {{cite conference|author=Husam Omar and Mohsen Issa|title=Cost Effectiveness of Lunar Concrete for Lunar Structures|booktitle=Pacific International Conference on Aerospace Science and Technology, Taiwan, Republic of China, December 6&ndash;9, 1993|date=1993}}
* {{cite conference|title=Feasibility of dual technology in manufacturing lunar concrete|author=Husam A. Omar and Mohsen Issa|pages=933&ndash;941|booktitle=Engineering, construction, and operations in space IV: Space '94; Proceedings of the 4th International Conference, Albuquerque, New Mexico, February 26&ndash;March 3, 1994|volume=2|date=1994|editor=Rodney G. Galloway and Stanley Lokaj|location=New York|publisher=[[American Society of Civil Engineers]]|id=ISBN 0872629376}}
* {{cite conference|title=Production of Lunar Concrete Using Molten Sulfur|author=Husam A. Omar and Mohsen Issa|pages=952&ndash;959|booktitle=Engineering, construction, and operations in space IV: Space '94; Proceedings of the 4th International Conference, Albuquerque, New Mexico, February 26&ndash;March 3, 1994|volume=2|date=1994|editor=Rodney G. Galloway and Stanley Lokaj|location=New York|publisher=[[American Society of Civil Engineers]]|id=ISBN 0872629376|url=http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19980001900_1997093192.pdf|format=PDF}}
* {{cite conference|title=Feasibility and Applications of Sulfur Concrete for Lunar Base Development: A Preliminary Study|author=I. Casanova|booktitle=28th Annual Lunar and Planetary Science Conference, March 17&ndash;21, 1997, Houston, TX|pages=209|url=http://www.lpi.usra.edu/meetings/lpsc97/pdf/1483.PDF|format=PDF|date=1997}}
* {{cite journal|author=T. D. Lin, Steven B. Skaar, and Joseph J. O'Gallagher|title=Proposed remote control solar powered concrete production experiment on the Moon|journal=Aerosp. Engineering|volume=10|issue=2|pages=104&ndash;109|date=April 1997}}
* {{cite conference|title=Strength and Durability Performance of Waterless Lunar Concrete|author=Houssam Toutanji, Becca Glenn-Loper, and Beth Schrayshuen|booktitle=43rd AIAA Aerospace Sciences Meeting and Exhibit 10 &ndash; 13 January 2005, Reno, Nevada|date=2005|publisher=American Institute of Aeronautics and Astronautics|url=http://pdf.aiaa.org/preview/CDReadyMASM05_666/PV2005_1436.pdf|format=PDF}}
* {{cite conference|author=R.N. Grugel, and Houssam Toutanji|title=Viability of Sulfur "Concrete" on the Moon: Environmental Consideration|booktitle=Proceedings:  43rd American Institute of Aeronautics and Astronautics (AIAA), Reno, NV, Jan. 9-12, 2006|date=2006}} &mdash; also:
** {{cite journal|author=R. Grugel, and Houssam Toutanji|date=2006|title=Viability of Sulfur Concrete on the Moon: Environmental Considerations|journal=Journal of Advances in Space Research}}
* {{cite conference|title=Production of Glass Fibers for Reinforcement of Lunar Concrete|booktitle=44th American Institute of Aeronautics and Astronautics (AIAA) Conference, Reno, NV, January 9&ndash;12, 2006|date=2006|author=E.C. Ethridge, D.S. Tucker, and Houssam Toutanji}}
* {{cite journal|doi=10.1016/j.asr.2007.08.018|title=Sulfur "concrete" for lunar applications &mdash; Sublimation concerns|author=Richard N. Grugela and Houssam Toutanji|journal=Advances in Space Research|volume=41|issue=1|date=2008|pages=103&ndash;112}}

== See also ==
* [[In Situ Resource Utilization]]

[[Category:Concrete]]
[[Category:Building materials]]
[[Category:Exploration of the Moon]]
[[Category:Space colonization]]
[[Category:2Fix]]