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The quality of concrete construction conventionally relies on the workability and consolidation of the concrete mixture. Practically speaking, the higher the amount of water used, the better the workability of fresh concrete; however, the use of excessive amounts of water will induce some detrimental effects on the quality of concrete. For example, the increase of water content in concrete mix proportions may reduce the bonding strength between cement paste and aggregate interface because of the voids and possibility of bleeding. To deal with this problem, compaction technology is adopted to produce precasted segments. A specific dry concrete mixture containing fly ash is calculated from the minimum-void concept, and the dry mixing method is selected to process the mix. The test results reveal that segments with homogeneous quality and excellent engineering properties can be obtained by a 3-min high-pressure compaction process and 1- to 2-day moist-curing. From experience, the automated process of production is also feasible, and it is proposed that the properties of segment using compaction and similarity technology from this study have great possibilities in lunar base construction.

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.

The recently established Lunar/Mars Program Office at Johnson Space Center is studying options that include construction of lunar outposts in the early twenty-first century, and subsequent structures for industrial operations. Major industrialization on the moon cannot occur without access to lunar resources. Construction of such structures as large pressurized habitats, launching facilities, lunar surface transportation systems, and liquefied oxygen storage tanks requires enormous volumes of materials. Experiments sponsored by the National Aeoronautics and Space Administration (NASA) and carried out at construction technology laboratories show the following: cements can be made from lunar anorthite and basalt; concrete made with lunar soils as aggregate has strength exceeding 10,000 psi; and a dry mixture of cement and aggregate wetted by injected steam will simplify concreting procedures and minimize needs for water and heavy equipment. In addition, a preliminary analysis of a prestressed precast concrete structure measuring 120 ft in diameter and 72 ft high shows that a properly designed concrete structure can confine atmospheric internal pressure. This project further investigates the effect of lunar temperature extremes on the behavior of precast concrete panels during the construction period. The major work involves calculations of heat flow in concrete panels exposed to the sun on the lunar surface and thermal stresses in the panels caused by the transient heat flow. Computer programs were written for the computations and results are presented.

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.

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.