Lunarcrete is an umbrella term for ‘concrete made on the moon’. As the US and China race to establish long-term lunar settlements, scientists are looking for a suitable building material to protect people from hazardous radiation and drastic temperature swings. Lunarcrete is one promising candidate: instead of sand and gravel, it uses lunar regolith, the grey soil that covers the moon, as its main aggregate. One challenge however is the binder: while Portland cement uses lots of water on the earth, water is a precious resource on the moon. So researchers are exploring options that minimise or eliminate the need for water.
One option is to ship some cement (or another binder) from the earth and combine it with regolith using minimal water and curing inside sealed habitats. Another is sulphur lunarcrete, where scientists melt sulphur, mix it with regolith, and let it cool into a solid. Sulphur can act like cement without water but it softens if it gets too hot. A third idea is to heat regolith with microwaves or concentrated sunlight so the grains partly melt and fuse, creating bricks.
Recently, Louisiana State University researchers led by Arup Bhattacharya simulated a dome-shaped lunar habitat with lunarcrete walls. When they subjected it to temperatures from 120 C to –130 C, they found the walls could preserve the temperature inside at 22 C. Walls made of two layers of lunarcrete with a layer of empty space in between were also found to be excellent insulators.
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