European researchers have found that the urea in human urine can be used as a “plasticizer” to combine with lunar regolith to make building materials.
The cost of transporting building materials to the Moon is so expensive — roughly $10,000 per pound — that scientists are looking for ways to utilize materials readily available on the Moon. Dutch, Norwegian, Spanish and Italian researchers theorized that urea could be incorporated into concrete to soften the initial mixture and make it more liable before it hardens, reports Phys.org.
“To make geopolymer concrete that will be used on the moon, the idea is to use what is already there: regolith (loose material from the moon’s surface) and the water from the ice present in some areas,” explains one of the authors, Ramón Pamies, a professor at the Polytechnic University of Cartagena (Murcia). “But moreover, with this study, we have seen that a waste product, such as the urine of the personnel who occupy the moon bases, could also be used. The two main components of urine are water and urea, a molecule that allows the hydrogen bonds to be broken and, therefore, reduces the viscosities of many aqueous mixtures.”
Using material similar to regolith mixed with urea, researchers have manufactured concrete cylinders using a 3-D printer. The urea mixture supported heavy weights and remained almost stable in shape. Resistance was tested at a temperature of 80°C, and was found to increase even after eight freeze-thaw cycles like those on the Moon.
Next step: figuring out how to extract the urea from the urine.