Professor Norm Wagner of the University of Delaware and his research team investigate the feasibility of producing construction materials on the moon and Mars.
Clay-like topsoil elements from the moon or Mars are of interest to researchers as a potential foundation for cement that can be used in extra-terrestrial construction. A chemical binder to hold the extra-terrestrial ingredients together is essential for this project’s success.
The vertical launch pads used to launch and land man-made rockets require an extra-terrestrial building material that can withstand the whirlwind of pebbles, dust, and other particles that can be kicked up during the launch and landing processes.
Most traditional building materials, such as regular cement, are unsuitable for use in the conditions of space.
The Research
Dr. Jennifer Mills, Dr. Maria Katzarova, and Professor Norman Wagner from the University of Delaware researched to come up with cutting-edge technology that will help with long-term exploration and living in space.
They came up with a way to compare lunar and Martian bedrock simulant-based geopolymer binders made through alkali activation for ISRU. The effects of extreme temperatures, vacuum, and high temperatures on the durability of the binder cement were also investigated.
They started by making geopolymer binders out of materials that looked like lunar and Martian bedrock. Lastly, they looked at the properties of the material and how the microstructure of the geopolymer binders changed in different environments.
The Cement
Common clays can be found all over the world, from Newark, Delaware’s White Clay Creek to the sands of Africa, and these clays are rich in aluminosilicate minerals, which are the building blocks of geopolymers.
Sodium silicate and other high-pH solvents can dissolve the clay, releasing its aluminum and silicon components for use in chemical reactions that produce new structures, such as cement. The soil of the moon and Mars also contains ordinary clays.
Results
Alkali activation with sodium silicate was used to turn one Martian regolith simulant and three lunar bedrock simulants into geopolymer binders, which the researchers said worked well. For effective activation of Martian simulant, they suggested lowering the solid content and raising the amorphous aluminosilicate content.
This is because small particles and aluminosilicate increase the overall strength of the binders when they cure at room temperature. All three lunar simulant binders decreased in a vacuum and low temperatures but rose above 600 °C. Due to the high amount of magnesium and iron, the overall strength of Martian binders went down when they were heated.
Variability in bedrock simulant mineralogy, shape, and chemical composition affected final binder mechanical characteristics. Comparing the strength properties of the binders to those in the research also brought out the effects of these parameters on the overall strength, even though the composition and processing methods were different.
Conclusion
Dr. Wagner added that,
“This is not a trivial thing. You can’t just say give me any old clay, and I’ll make it work. There are metrics to it, chemistry that you have to worry about,”
These findings can also be applied to the production of geopolymer cement on Earth, which is better for the environment and can be derived from a greater variety of materials found locally.
In addition, the water consumption in the reaction is reduced by using geopolymer cement instead of regular cement. Instead, the water can be captured, purified, and reused, which is beneficial in water-scarce settings like dry terrestrial landscapes and interplanetary missions.
