Embedding Unidirectional Carbon Fibers into Regolith Simulants for In-Space Manufacturing of Structural Shields for Future Settlements

The creation of new settlements on the Moon is an extraordinary opportunity for both economic and research purposes, but it is hindered by the prohibitive costs of transporting materials from Earth. In this frame, in situ resource utilization (ISRU) can significantly reduce these costs by exploiting lunar regolith, the Moon’s most abundant resource. In this work, a lunar regolith simulant is aggregated by an innovative manufacturing process based on geopolymerization. Bricks were obtained by mixing the simulant with a small amount of sodium hydroxide solution, followed by cold compaction at 20 MPa and oven drying at 500 °C for 1 h. Regolith bricks reinforced with unidirectional dry carbon fibers were manufactured by alternating the regolith-based mixture with layers of CFs. Mechanical properties were evaluated by bending and compression tests. Neat bricks were manufactured for comparison. Improvements in mechanical behavior were obtained thanks to fiber insertion, mainly in terms of resilience, even if stress at break is not improved. In compression, fibers limit brittle behavior, resulting in an average increase in toughness of 59.5%. Fast curing time and limited water consumption, compared to the traditional geopolymerization process, make this manufacturing process highly attractive to obtain lunar regolith bricks.