How scientists plan to turn the soil on Mars and the Moon into concrete

Concrete is a necessary material for construction, but outside space, producing this material is extremely difficult and completely different from what we are doing on Earth.

Needless to say, many of us may already know that in the near future, if humans live on Mars, the Moon or any planet in distant space, they will experience a life is mainly based on self-sufficiency.

This means they will need to have the necessary facilities to produce their own food, fuel and even air on site. To do that, however, they must first obtain a safe haven, and building a permanent settlement away from Earth is perhaps the most difficult of them all.

According to current calculations, the cost to carry 1kg of cargo outside with the SpaceX Falcon, the rocket currently regularly used to supply the International Space Station will cost about 2,700 USD (about 632 million VND). .

However, the cost to send a kilogram of material to Mars will cost many times more - Mars Curiosity costs about $2.5 billion to land an 889 kg rover to Mars, at a cost cost per kg about 2.78 million dollars.

And even if you have a lot of money, the maximum load in each journey is limited, so we can't ship any building materials to Mars or even the Moon.

 We cannot ship any building materials to Mars or the Moon.

Even so, geologists and chemists at the University of Delaware have a promising idea: to use the natural resources already in the destination to produce building materials.

That may sound like the obvious thing to do, but turning Mars' surface materials into reliable and effective building materials has been far from straightforward with previous research.

A key requirement for any extraterrestrial settlement is durability and strength. And at this point, concrete is a great choice, but the recipe to produce concrete requires cement bridges - a material that cannot be carried in space.

 Geopolymers are inorganic polymers.

To get around this, researchers led by University of Delaware professor Norman Wagner turned to geopolymer chemistry. Geopolymers are inorganic polymers composed of aluminosilicate minerals that form a ceramic-like solid material at near ambient temperatures. On Earth, they are commonly found in clay almost everywhere in the world.

When these geopolymers are mixed with an alkaloid solvent, such as sodium silicate, the clay is dissolved, releasing aluminum and silicon to react with other substances and form new materials - and this includes cement.

Soil on Mars or the Moon also contains these common clays, but doing so outside of Earth is "not easy," Wagner said. 'You can't just say that with just clay we can successfully do this process. However, there are measures of accuracy, and chemical factors that you have to take into account for the extraterrestrial environment."

For this new study, the scientists mixed simulated Mars and Moon soil with sodium silicate, then molded the liquid mixture in cube-shaped molds. After a week, the material from each block mold is removed, measured and weighed, before they are structurally tested to see how much load they can withstand. Materials are also subject to various environmental factors they would encounter in space, including vacuum, as well as high and low temperatures.

"When a rocket takes off, there's a lot of weight pushing down on the landing pad, so the compressive strength of the material becomes an important metric. At least on Earth, we've got that," Wagner said. can produce materials in the form of small cubes with the compressive strength needed to do the job."

. Tests show that geopolymer cement has poor compressive strength when formed under vacuum conditions.

Researchers have reported the successful conversion of one regolith simulator on Mars and three regolith simulators on the Moon into a geopolymer binder. Tests show that geopolymer cement has poor compressive strength when formed under vacuum conditions. Meanwhile, at a temperature of -80 degrees Celsius and below, the geopolymer does not undergo a chemical reaction at all. This suggests that the astronauts would have to cast these materials in a pressurized environment and that the geopolymer would have to be heated.

Instead of packing sacks of cement to send to Mars, with the results of this study, astronauts only need to carry solvent with them. The amount they need to build a moderately sized settlement could be well suited to the payload range of a rocket launched to Mars.

Geopolymers require less water than traditional cement to produce because the water itself is not absorbed by the reaction. This means it can be recovered and reused. Researchers at the University of Delaware are busy building 3D-printed houses using geopolymer cement, which they plan to activate using microwave technology.