lunar production of steel, aluminium, or brick. It is unaffected by temperature variations of +120 °C to −150 °C. It will absorb gamma rays. 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. 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. 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. See also Lunar resources References Further reading — also: Concrete Building materials Exploration of the Moon Colonization of the Moon Industry in space Exploration of Mars Colonization of Mars