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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
Document:
SP125-01
Date:
May 1, 1991
Author(s):
G. D. Nasser
Publication:
Symposium Papers
Volume:
125
Abstract:
The age of space exploration is already here and it appears likely that, in the next 20 years, there will be permanent bases on the moon. Therefore, it is incumbent upon engineers designing lunar structures to become knowledgeable about the peculiar effects of gravity and relativity under extraterrestrial conditions. The purpose of the paper is to present a review of Newtonian physics in light of Einstein's special and general theories of relativity. In particular, Newton's classic laws of motion and gravitation are compared with modern concepts of space-time, time dilation, length contraction, equivalency principle, and other interesting aspects of relativity.
DOI:
10.14359/3679
SP125-03
David O. Swint and S. R. Schmidt
The United States Air Force Academy's Engineering 410 class, Spring 1989, tested the feasibility of using concrete as a lunar construction material. This was a continuation of two previous semesters' effort. Concrete specimens were tested by combining different cement types, mixing environments, and additives to determine their effects on strengths and other engineering properties of the specimens. Using 5 different variables, a total of 80 possible combinations existed. The group used a D-optimal design with 18 possible combinations to build a prediction equation to optimize the concrete design mixture. Confirmation tests were conducted on the optimal design and compared with the mathematical algorithm prediction. The results demonstrate the power of this approach in experimentation for concrete applications.
10.14359/3691
SP125-02
Shinji Matsumoto, Tetsuji yoshida, and Kenji Takagi
Lunar base concepts utilizing concrete as structural material have been proposed recently. These are based on the consideration that oxygen and raw materials used in manufacturing cement will be extracted from lunar resources and that the soils and rocks will be used as aggregates of concrete. The moon has an abundance of raw material used in manufacturing cement within its rocky soil, thus requiring rocks to be crushed. The paper discusses a unique rock-breaking system using plentiful solar energy available on the moon: that is, sudden heating of a rock surface induces high thermal stress within the rock, which results in the rock breaking. Appropriate heat flow and radiating time are calculated using the physical property of basalt, which has a similar chemical composition to lunar rock. Additionally, required system volume is estimated.
10.14359/3698
SP125-05
Richard A. Kaden
The methodology for forming and placing lunar concretes will incorporate our present technology as well as add the innovations that will be developed in the years to come. Initial habitation will combine the use of inflatable forms, precast modules, and self-contained modules that are landed on the lunar surface. The forming and placing systems used for cast-in-place lunar concrete may include temporary stay-forms, preplaced aggregate concrete (which utilizes injection grouting), air-o-form system, and precast concrete. Lightweight fiberglass formties have great potential for lunar construction. A case history and discussion for preplaced aggregate concrete usage is provided for the Peoria Lock Resurfacing Project. The placement size was 1 ft (0.3048 m) wide x 40 ft (12.2 m) long x 10 ft (3.1 m) deep. The maximum size aggregate was 3 in. (7.6 cm) for increased economy. Typically, the angle of repose for the grout was 1:10. Test results for 7-day and 28-day compressive strengths for 2 in. (5 cm) mortar cubes, preplaced aggregate concrete cylinders, and conventional concrete are given. Other items discussed in the article are concretes for a lunar landing support facility, modified shotcreting and curing methods, and a variety of modified inflatable form structures.
10.14359/3709
SP125-04
Hiroshi Kanamori, Shinji Matsumoto, and Noboru Ishikawad
Effects of a vacuum environment on properties of hardened mortar made with cement-based materials are discussed. In this study, mortar specimens were exposed to a vacuum environment after various water curing periods. Several characteristics of the specimens, such as weight, strain, porosity, and strength, were measured before and after the vacuum exposure. A significant water loss and shrinkage strain were observed in tested specimens after specific vacuum exposure. Therefore, some measures are required to prevent shrinkage-induced cracks. In some cases, strengths for some vacuum-exposed mortar specimens were higher than water-cured companion specimens. Based on these experimental results, possible applications of concrete on the moon are recommended in this study.
10.14359/2415
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