International Concrete Abstracts Portal

An important aspect of lunar concrete production will be the production of lime (CaO) from lunar rocks. Chemical and thermodynamic data show that lime could most easily be distracted from abundant lunar anorthite (CaAl2Si2O8) the major mineral in the anorthositic lunar highlands. If fluorine gas, produced on site by electrolysis of molten NaF, is used as the extracting agent, oxygen, silicon, and aluminum can be recovered at the same time. Of these, oxygen is likely to be the most valuable product. Lime is recovered from fluorite, CaF2, by reaction with soda, Na2O; the resulting NaF is recycled into fluorine production immediately before use. No fluorine gas is transported or stored in this process; it is used up as soon as it is made.

This paper suggests establishing the applicability and manufacturing technique of GFRP, particularly dimethylisophtalate glass-filament rod. The use of GFRP reinforcement in lieu of conventional steel rods and wires has great potential for precast structural concrete elements. GFRP may be cheaper, lighter, and formed from materials found in abundance on earth and on the moon, namely silica (SiO2). GFRP can be manufactured with the same, if not higher, tensile properties of steel. If synergically composed with a plastic carrier, a new science in construction and structural analysis could be born. No doubt remains that lunar soil is cementitious. Rocks for aggregate and silica are also abundant on the moon. Heavy fabricated steel rods are counterproductive for transport to the moon. Glass fibers fabricated on the moon have great potential. Permanent settlement/habitats on the moon are within the realm of possibility and may be considered immediate projects. Therefore, the idea of using local materials is appropriate within the concept of a third phase of permanent underground reinforced concrete construction facilities, the first being the Apollo landings and the second a temporary above-ground lunar establishment yet to come. This analysis could lend itself not only to permanent reinforced concrete structures on the moon, but to any other planet where silica is abundant and cement could become a local product, through refining and reducing appropriate local ores. Manufacture of glass-fiber filaments is incomparably cheaper than steel. Additional research, at a later date, will encompass the application of pre- and post-tensioned GFRP reinforcements, using the same structural form elements. This paper proves the positive applicability of GFRP as reinforcement for precast concrete elements.

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.

Lunar Concrete is the exciting new symposium volume which explores the production and use of concrete on the moon. Contained within 20 technical papers from well-known authorities on lunar concrete are details on lunar base construction, use of lunar resources, lunar concrete formulation, forming and placing lunar concrete, reinforcing lunar concrete, and environmental effects of lunar concrete, optimizing lunar concrete and much more. It may at first seem outrageous that concrete could be considered as primary material of construction for use on the Moon. However, a small group of scientists and engineers, many of them represented in this collection of papers, have persevered in examining this outrageous premise. Most, perhaps all, of the materials needed to make concrete are naturally present on the lunar surface. Although they have to be extracted and transformed, the energy required to do that, and probably the cost, is much less than that which would be required to bring the same quantity of material from the Earth to use on the Moon. The technology for utilizing these natural materials of the Moon would appear to be straightforward modifications of techniques that have been developed for terrestrial applications. Note: The individual papers are also available as .pdf downloads.. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP125

Based on the available data on abundance and composition of lunar materials, lunar basalts were selected as a prospective base source for cement production. Methods of increasing calcium content of natural raw materials were developed. The experimental study was conducted in two directions: sintering mixes of natural materials with CaO and activating mineral glasses obtained by beneficiation of the natural rocks. In both cases, the terrestrial materials were selected to simulate the lunar rocks. The sintered cement exhibited properties analogous to those of known portland cements. The vitreous material simulating the composition of beneficiated lunar rocks developed cementitious properties when it was activated by the chemical agent and cured under the conditions of high humidity and elevated temperatures.