Lunar regolith is the preferred material for lunar base construction using in situ resource utilization technology. The TiO2 variations in lunar regolith collected from different locations significantly impact its suitability as a construction material. Therefore, it is crucial to investigate the effects of TiO2 on the properties of lunar regolith. This study aims to evaluate the influence of TiO2 content and sintering temperature on phase transformation, microstructure, and macroscopic properties (e.g., the shrinkage rate, mechanical properties, and relative density) of lunar regolith simulant samples (CUG-1A). The flexural strength and relative density of the sample with a TiO2 content of 6 wt% sintered at 1100 C-degrees reached 136.66 +/- 4.92 MPa and 91.06%, which were 65% and 12.28% higher than those of the sample not doped with TiO2, respectively. The experiment demonstrated that the doped TiO2 not only reacted with Fe to form pseudobrookite (Fe2TiO5) but also effectively reduced the viscosity of the glass phase during heat treatment. As the sintering temperature increased, the particles underwent a gradual melting process, leading to a higher proportion of the liquid phase. The higher liquid-phase content had a positive impact on the diffusion of mass transfer, causing the voids and gaps between particles to shrink. This shrinkage resulted in greater density and, ultimately, improved the mechanical properties of the material.

Ever since the Lunar Crater Observation and Sensing Satellite (LCROSS) data helped confirm the presence of water in the permanently shadowed regions (PSRs) of the lunar polar area, interest in developing systems for the production of water on the Moon has peaked. Considering the extremely cold environment on the lunar surface, geotechnical properties of icy lunar regolith could have notable variance depending on water content and cryogenic environment. It is essential to have an in-depth understanding of the geotechnical properties of icy lunar regolith under varying conditions such as different water contents and cryogenic temperatures. Previous studies have shown that icy regolith behaves similarly to rock, depending on the water content and degree of compaction. Characterizing icy regolith is critical for any drilling and excavation operations for the development of the bases or for mining activities. This study estimated geotechnical behaviors of icy lunar regolith in cryogenic environments. Geotechnical tests such as unconfined compressive strength (UCS), Brazilian tensile strength (BTS), and punch penetration tests were conducted in simulated lunar cryogenic environments on samples of basaltic lunar simulant with changing water content. The results indicate that geotechnical properties of icy lunar regolith vary substantially in simulated moon environments. Icy lunar regolith tends to behave like rock with soft to medium strengths but has nonbrittle (or ductile) properties. Correlations between strength properties and water content as well as between strength properties and cryogenic temperature are offered. The results of this paper could provide valuable suggestions for future mining and civil activities and other exploration purposes on the moon. The results of mechanical characterization of icy regolith provided in this paper, such as UCS, BTS, and punch penetration tests to determine ductility and brittleness, are among the novel aspect of the study to offer better understanding of the behavior of such materials in future mining and construction activities on the moon.