An overview on lunar regolith simulants solidification methods: integrating chemical, physical, and MICP strategies for extraterrestrial construction

As lunar exploration progresses toward long-term human habitation, the demand for sustainable construction materials has become increasingly urgent. Lunar regolith, the primary in-situ resource utilization (ISRU) for infrastructure development, poses significant challenges due to its unconsolidated nature and extreme environmental conditions. To establish a fundamental understanding of lunar regolith as a building material, this study first provides a comprehensive review of the distribution, physical and mechanical properties, and mineralogical composition of lunar regolith. Due to the limited availability of real lunar soil, most existing studies rely on lunar regolith simulants (LRS) to mimic lunar conditions; therefore, LRS are also included in this review. Then emphasizing their broad particle size distribution, angular morphology, and low cohesion, which collectively hinder direct structural applications. Given these intrinsic limitations, effective solidification strategies are required to enhance mechanical stability and environmental resilience of LRS. To this end, this study systematically reviews four primary solidification methods including polymer, geopolymer, sintering, and microbially induced carbonate precipitation (MICP) solidification—through an in-depth analysis of their reaction mechanisms, mechanical performance, and adaptability to lunar conditions. Each method is assessed based on its ability to improve cohesive strength, structural integrity, and durability, with particular focus on their chemical bonding mechanisms, material densification processes, and long-term performance under extraterrestrial conditions. However, lunar infrastructure must not only achieve sufficient cohesive strength but also withstand extreme environmental conditions. Therefore, this study further reviews the effects of vacuum exposure, high-temperature fluctuations and low-temperature conditions on the long-term stability of solidified LRS. By evaluating the interplay between material properties, solidification methods, and environmental adaptability, this study provides critical insights into optimizing durable, resource-efficient construction strategies for lunar infrastructure.