Silicate-lunar regolith composite: a vacuum self-hardened and comprehensively durable extraterrestrial construction material

• Main Authors: Geng, Zifan., Zhang, Lizhi, Wu, Zhiwen, Huang, Jiale, Wang, Xiangyu, Tan, Ming Jen, She, Wei, Zhou, Hao, Geng, Guoqing
• Other Authors: School of Mechanical and Aerospace Engineering
• Format: Article
• Language: English
• Published: 2024
• Subjects: Engineering; Extraterrestrial construction; Lunar regolith
• Online Access: https://hdl.handle.net/10356/180775
• Institution: Nanyang Technological University

Extraterrestrial exploration, represented by Lunar base construction, has been promoted worldwide as a multi-disciplinary, cutting-edge and strategic issue. Herein we proposed a novel extraterrestrial construction material composed of Lunar/Martian regolith simulants and only 4 wt% of silicate adhesive. This silicate-regolith composite can be directly self-hardened in vacuum within 4.5 h without any curing to achieve 29 MPa of hardening strength. Meanwhile, it shows comprehensive durability with stable microstructures and >70 % of residual strength against long-term vacuum exposure, huge temperature difference and intense γ-ray and proton radiations. Its in-situ solidification and durability originate from vacuum dehydration, where silica clusters in solution spontaneously cohere into a solid network with strong connections of silica tetrahedra and bound water. A moderate silicate modulus around 2.5 and appropriate modifications can disperse finer silica clusters to increase oligomer silica units in solution and enhance hardening strength. Compared with lunar geopolymer and other existing extraterrestrial construction materials, this vacuum self-hardening composite allows a cryogenic preparation even below −40 ℃ using diverse regolith with a wide range of compositions and sizes, proposing a facile, durable and versatile solution towards in-situ extraterrestrial constructions.