Enhanced in-situ utilization of lunar simulant for fibre-reinforced high-performance concrete: Mechanical properties and cost-effectiveness for lunar applications

In pursuit of establishing a sustainable human presence on the Moon, the development of construction materials capable of enduring the Moon’s harsh environmental conditions is of the utmost importance. This study examines the mechanical properties of fibre-reinforced lunar high-performance concrete (LHPC), which was fabricated using a significant proportion of lunar simulant. A systematic analysis was conducted on the influence of fibre type, dosage, and combination (mono and hybrid) on workability, unit weight, microstructure, and compressive and flexural performance of LHPC. Moreover, this study introduces a concept of mass-strength efficiency to demonstrate the feasibility and benefit of fibre reinforcement and in-situ resource utilization (ISRU) for construction purposes on the Moon. Results indicated that while fibre addition reduced workability, it increased the unit weight of LHPC. As compared to the control, the fibre reinforcement significantly improved mechanical properties, with the highest 28-day compressive and flexural strengths recorded at 125.2 MPa and 11.5 MPa, respectively. Furthermore, all fibre-reinforced specimens maintained structural integrity under the compressive loads, and those with mono steel or hybrid steel-polypropylene (PP) fibres exhibited a wide principal fracture bridged by intact fibres after bending tests. Microstructural morphology confirmed effective fibre-matrix adhesion and highlighted distinct failure mechanisms of mechanical interlocking for steel fibres and failure through breakage for PP fibres. However, steel fibres in the hybrid system mitigated rapid crack propagation, resulting in slight necking and pull-out deformation of PP fibres. The enhanced mass-strength efficiency implied notable transportation cost savings, potentially up to $19,880 per kilogram of Earth-to-Moon materials. In general, a hybrid LHPC mix emerges as a viable solution for lunar bases, optimizing both mechanical properties and logistical efficiency.