NASA tests space concrete for future Mars habitats

NASA is considering a future where humans could visit Mars for a long time, and Elon Musk promises to send people there over the next decade. Whenever humans set foot on Mars, they will need a place to hang their hat (or space suit helmet). Concrete could eventually allow explorers to build structures quickly and easily, assuming that it poses properly without gravity Earthly. NASA conducted experiments aboard the International Space Station (ISS) to assess the strength of mixed concrete in space.

Scientists believe that concrete could be an ideal material to build on other worlds because it is durable, protects against radiation and can be made from materials found on the Moon and Mars. Being able to build construction materials on your destination (in situ resources) makes missions cheaper and easier to design because you do not have to throw as much mass from Earth.

However, we still do not know much about the molecular structure of concrete on Earth. Concrete is a mixture of sand and gravel with lime or silicate (cement powder). When the cement dissolves in the water, it forms crystalline complexes that connect the aggregates to form a solid structure. The mixing and building process with concrete is well established on Earth, but we do not know how microgravity could affect it. Do we need to change the ratios? Add additional materials? This is what the ISS experiment seeks to discover.

ISS concrete above and concrete below.

The experiment, called Microgravity Investigation of Cement Solidification (MICS), is the first time that concrete is mixed outside of Earth's gravity. Astronauts aboard the ISS mixed tricalcium silicate and water in varying amounts to create a concrete paste. Astronauts have added alcohol to some of the packages to stop the hydration process at defined intervals. A separate experiment used centrifugation simulated by lunar and Martian gravity on the samples as they mixed.

The experience confirms that concrete can harden in microgravity, which is a good thing. This means that we can build structures with concrete outside Earth's gravity. The main difference is an increase in pores compared to mixed concrete on Earth, which could reduce the strength of the material. However, a lower gravity on the Moon or Mars would also subject it to less tension. It may be possible to develop different binders that improve the strength of lunar or martian concrete and that could even lead to better concrete here on Earth.

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