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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 21 Abstracts search results
May 1, 1991
Joseph J. O'Gallagher and T. D. Lin
In the lunar environment, the use of solar thermal energy has obvious advantages over any combustion or electrical furnace for driving high-temperature processes. However, extremely high temperatures, in the range of 1700 to 2000 C, will be necessary to produce cement from lunar minerals and will, in turn, require very high levels of solar flux concentration. Such levels can only be achieved in practice with some form of ideal or near-ideal nonimaging concentrator that can approach the maximum concentration permitted by physical conservation laws. In particular, very substantial gains in efficiency can be generated through the incorporation of a properly designed ideal or near-ideal nonimaging secondary concentrator in a two-stage configuration with a long focal ratio primary concentrator. A preliminary design configuration for such a high-flux nonimaging solar concentrating furnace for lunar applications is presented. It employs a tracking heliostat and a fixed, off-axis, two-stage concentrator with a long focal length utilizing a nonimaging trumpet or CPC-type secondary deployed in the focal zone of the primary. An analysis of the benefits associated with this configuration employed as a solar furnace in the lunar environment shows that the thermal conversion efficiency can be about 3 to 5 times that of the corresponding conventional design at 2000 C. Furthermore, this configuration allows the primary collecting aperture to remain unshaded by the furnace or any associated support structure.
H. A. Franklin
In July 1989, those who advocate U.S. space programs received a significant boost from President Bush's declaration that the U.S. should return to the moon (this time to stay) and then go on to Mars. Achieving these objectives will thrust engineers of ma
P. A. Hart, S. D. Howe, S. W. Johnson, G. G. Leigh, and R. S. Leonard
Concrete-like materials can be envisioned for applications in the construction of a lunar base in the next century. Although the technology for the manufacture and use of such materials on the moon is not yet available, many people have begun to investigate the possibilities for applications of cements and concretes adapted to the lunar environment. It will be essential that enabling technologies and processes for lunar concrete be developed and proven to have a high degree of reliability. Equipment and operational procedures must then be thoroughly tested under realistic conditions before commitment to lunar base construction. The authors believe that a need exists for a major center of knowledge and education with a simulation facility, where the technologies for lunar and Mars operations can be verified for effectiveness and suitability, to preclude costly surprises and breakdowns in extraterrestrial operations. The authors are planning a Center for Extraterrestrial Engineering and Construction (CETEC), which will serve such a purpose. The CETEC group encompasses many people from across the nation representing national laboratories, universities, constructors, aerospace firms, research and development companies, government, and small business. CETEC will give developers of lunar concrete access to necessary expertise and test facilities to achieve the goals of the space exploration initiative. At CETEC, simulated materials of the moon and Mars will be available in vacuumin appropriate hot and cold dusty environments, so that concepts and prototype equipment for cement and concrete production and use can be verified on a large enough scale to satisfy skeptics and advance all uses of in situ lunar materials for the benefit of humankind.
Philip J. Richter, Richard M.Drake, and Ed Drake, and Ed M. Repic.
Provides an overview of engineering studies performed in support of the Space Exploration Institute (SEI). Topics addressed include background on the SEI, lunar construction phases, lunar habitats, lunar oxygen, mechanical concepts, and lunar power. Although the topics do not relate equally to concrete construction, they do identify selected issues that must be addressed before a lunar outpost can evolve to the emplacement and operation phases. In these phases of lunar outpost development, maximum use will be made of native materials, such as lunar concrete.
Richard M. Drake
It has been proposed that a large pressurized shirt sleeve environment assembly facility would be useful during all phases of lunar outpost development. This article discusses the use of such a facility during later phases of outpost development when use of native materials is maximized. The principle benefits from the use of a large pressurized facility are that workers needn't wear cumbersome, restrictive space suits and concrete needn't be cured in the vacuum environment of the moon. A specific assembly facility concept is presented and its conversion to a lunar precast concrete plant is discussed.
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