The exploration of the Moon necessitates sustainable habitat construction. Establishing a permanent base on the Moon requires solutions for challenges such as transportation costs and logistics, driving the emphasis on In-Situ Resource Utilization (ISRU) techniques including Additive Manufacturing. Given the limited availability of regolith on Earth, researchers utilize simulants in laboratory studies to advance technologies essential for future Moon missions. Despite advancements, a comprehensive understanding of the fundamental properties and processing parameters of sintered lunar regolith still needs to be studied, demonstrating the need for further research. Here, we investigated the fundamental properties of lunar regolith simulant material with respect to the stereolithography-based AM process needed for the engineering design of complex items for lunar applications. Material and mechanical characterization of milled and sintered LHS-1 lunar regolith was done. Test specimens, based on ASTM standards, were fabricated from a 70 wt% (48.4 vol %) LHS-1 regolith simulant suspension and sintered up to 1150 degrees C. The compressive, tensile, and flexural strengths were (510.7 +/- 133.8) MPa, (8.0 +/- 0.9) MPa, and (200.3 +/- 49.3) MPa respectively, surpassing values reported in previous studies. These improved mechanical properties are attributed to suspension's powder loading, layer thickness, exposure time, and sintering temperature. A set of regolith physical and mechanical fundamental material properties was built based on laboratory evaluation and prepared for utilization, with the manufacturing of complex-shaped objects demonstrating the technology's capability for engineering design problems.

The quest for viable construction materials for lunar bases has directed scientific inquiry towards the lunar in-situ resource utilization (ISRU), notably lunar regolith, to synthesize concrete. This study develops an innovative lunar high strength concrete (LHSC) utilizing lunar highlands simulant (LHS-1) and lunar mare simulant (LMS-1) as both precursors and aggregates within the concrete matrix. Mixtures were cured under the conditions simulating the lunar surface temperatures, enabling an evaluation of properties such as flowability, unit weight, compressive strength, modulus of elasticity, and microstructure patterns. Test results indicated that the LMS-1 mixtures exhibited a better flowability and higher unit weight as compared to LHS-1 counterparts. Moreover, the highest 28-day strength was 106.7 MPa and 98.7 MPa for LHS-1 and LMS-1 derived LHSC, respectively. Microstructure analysis revealed that under the identical simulant additions, LHS-1 mixes exhibited superior structural compactness with denser amorphous gels and fewer microcracks. In addition, it possessed a lower Si/ Al ratio and diffraction peak of calcite, along with a greater Ca/Si ratio and hump intensity of amorphous gel phases. The development of this cement-free LHSC, incorporating up to 80 % large-scale lunar materials in the total binder mass, plays a critical role in advancing ISRU on the Moon, thus boosting the viability and sustainability of future lunar construction and habitation while significantly reducing transportation and fabrication costs.

This review explores the development and potential applications of space concrete, a critical material for future extraterrestrial construction. Space concrete, adapted to withstand the harsh conditions of outer space, such as extreme temperatures, vacuum, microgravity, and radiation, offers a sustainable solution for building habitats and infrastructure on celestial bodies like the Moon and Mars. Emphasizing the innovative approaches in formulating space concrete, including the use of lunar and Martian soil as aggregates and the exploration of alternative binders to traditional water-based cement, this review highlights the significance of in-situ resource utilization (ISRU) and 3D printing technologies in advancing extraterrestrial construction. Additionally, the current designs and applications of space concrete structures are discussed. By providing a detailed analysis of the challenges faced in space construction and the latest advancements in material and structural research, the review underlines the pivotal role of space concrete in supporting space exploration and long-term habitat.

The construction of lunar bases has become a new target for lunar exploration by many space powers worldwide. Sintered lunar regolith is one of the most promising building materials for in situ resource utilization (ISRU). Spark plasma sintering (SPS) technology has the advantageous features of a fast sintering speed and high density. This study explored the feasibility of sintering a HUST-1 lunar regolith simulant using SPS technology. The physical, mechanical, and thermal properties, as well as the microstructure and phase composition of the sintered samples were investigated at multiple scales. In addition, the effects of the SPS conditions on the sintering results were studied, including the sintering temperature, heating rate, and applied pressure. The test results indicated that the sintering conditions significantly affected the sintered products. Finally, the thermal shock resistances of the sintered samples were investigated at simulated lunar temperatures. The samples were treated at two different temperature ranges, one from -60 to 60 degrees C (+60 degrees C) and another from -120 to 120 degrees C (+120 degrees C). The results showed that the sintered samples exhibited excellent thermal shock resistance in the extreme temperature environment of the lunar surface. After 100 thermal test cycles at + 60 degrees C and + 120 degrees C, the compressive strength increased by 16.0 % and 33.4 %, respectively. The reason for the increase in strength remains unclear. The Brunauer-Emmett-Teller (BET) test results showed that this may be caused by the gradual disappearance of micropores smaller than 10 nm during thermal cycling. (c) 2023 COSPAR. Published by Elsevier B.V. All rights reserved.