Scientists are exploring ways to make the strongest cement for Mars and the moon

• Researchers worldwide are developing new methods to build the space habitats of the future
• The key is finding ways to harness local off-world resources
• One group of scientists developed a geopolymer cement that can withstand rocket blasts

Researchers the world over are exploring new methods for building housing and other infrastructure off-world.

The technological limitations and prohibitive costs associated with transporting vast amounts of building materials mean that scientists are devising methods that utilize space resources.

One method comes from scientists at the University of Delaware. They believe space missions could one day use clay-like topsoil materials found on the moon and Mars as a basis for extraterrestrial cement, a press statement reveals.

Building on Mars and the moon

The scientists outlined their method for using clay-like topsoil materials to build future space habitats. "If we're going to live and work on another planet like Mars or the moon, we need to make concrete. But we can't take bags of concrete with us—we need to use local resources," said Norman Wagner, Unidel Robert L. Pigford Chair of Chemical and Biomolecular Engineering at the University of Delaware.

The researchers successfully converted simulated lunar and Martian soil into geopolymer cement, which is considered a suitable alternative to traditional cement. They published their findings in the journal Advances in Space Research.

Geopolymers are inorganic polymers formed from aluminosilicate minerals. They are found in common clays all over the world. When they are mixed with a solvent with a high pH, the clay can be dissolved, freeing the aluminum and silicon inside to react with other materials. This then allows the creation of cement.

Geopolymer mixture can withstand rocket blasts

The researchers set out to find out if simulated moon and Martian soils could be activated in a similar fashion using geopolymer chemistry. They mixed many different simulated soils with sodium silicate and cast the resulting geopolymer mixture into molds to observe the reaction. Specifically, they wanted to see if slight differences in chemistry would have a big impact on the overall strength of the resulting material.

In their paper, they explain that they were able to make materials in little cubes that have the compressive strength required to withstand the strength of a rocket blast. More investigation is, of course, needed to see how the material will hold up in space conditions. Based on their results though, the researchers laid out a few pointers that could help develop materials in space. Chemical composition and particle size, for example, can play a crucial role in material strength.

All of this adds to the growing scientific literature on space construction. It's a field that has had some pretty out-there proposals, due to the necessity for unorthodox methods — space is a harsh environment, meaning many traditional methods simply won't work. One scientist from the University of Manchester, for example, suggested last year that human blood and feces could be combined with lunar and Martian regolith as a binding agent for space cement.

With China having recently set its sights on sending astronauts to Mars in the 2030s, and SpaceX aiming to launch its Mars-bound Starship to orbit this summer, scientists are racing to find construction solutions for space. The cost of transporting a payload with the weight of a brick to Mars is currently close to $2 million, meaning such newly-devised methods are crucial to the construction of future space colonies.