"When developing materials for lunar construction, it is essential to minimize the weight of components that have to be brought in from Earth. All necessary ingredients for geopolymers could potentially be sourced on the lunar surface, which is why the material might be an efficient construction material for infrastructure on the moon. Finding a chemical admixture that can be easily obtained on the moon, which can increase the workability while utilizing less water, would be highly beneficial for utilizing lunar regolith geopolymers for lunar 3D printing. Urea can break hydrogen bonds, and therefore reduces the viscosities of many aqueous mixtures. Since urea is the second most abundant component in urine (after water), it is readily available anywhere there are humans. We have therefore explored the possibility of utilizing urea as a chemical admixture for lunar geopolymers..."https://www.sciencedirect.com/science/article/pii/S0959652619340478
