Bio-molding of lunar regolith with bio-carbonized magnesium oxide

As lunar exploration develops, lunar construction is increasingly prominent and the in-situ lunar regolith molding becomes a technical challenge. This study proposes a lunar regolith molding technology based on biocarbonated magnesium oxide (MgO) with urea pre-hydrolyzed, which has the potential to achieve an unconfined compressive strength (UCS) of approximately 10 MPa after 24 h of curing. The study investigates the physical and mechanical properties of biocarbonated lunar regolith samples with varying urea concentrations, bacterial concentrations, and MgO contents. Scanning electron microscopy (SEM) was employed to examine the microstructural properties of the samples. The results demonstrated that the maximum UCS and E50 were achieved at a urea concentration of 1.0 mol/L, a bacterial concentration of 1.0, and a MgO content of 15%. However, the carbonate content test indicated that the highest urea efficiency was observed at 10% MgO. Microscopic images show that the produced hydromagnesite is the most structured at the urea concentrations of 1.0 mol/L and 2.0 mol/L, corresponding well with the strength performance of the specimens. The pre-hydrolysis method can promote the efficiency of biocarbonated magnesium oxide but it highly depends on the concentration of the produced carbonate. Conclusively, the findings of this study offer a promising avenue for lunar regolith molding.