Robotically Emplaced Lattice Reinforcement for Lunarcrete Structures and ISRU

NASA requires versatile and robust in-situ resource utilization (ISRU) strategies for lunar construction. Many concepts propose using lunar regolith to form concrete, termed here generally as lunarcrete, to create structures like Lunar Safe Haven to protect astronauts and equipment from the micrometeor and radiation environment. Just like terrestrial concrete, lunarcrete is expected to have poor tensile strength and require reinforcement to build safe lunar structures under expected thermal and moon quake conditions. However, autonomous placement of continuous reinforcement remains a challenge for 3D printing strategies. The NASA ARMADAS project has demonstrated autonomous robotic assembly of lattice structures. We propose using this autonomously constructed lattice to build reinforcement and integral formwork for lunar construction. Rather than 3D printing concrete, structures could be cast in a similar manner to what is commonly done on Earth. This process would leverage much of the technology needed for lunarcrete 3D printing, but critically would reduce the precision needed for placement, mix control, rheology, etc. This process margin, when combined with the increased strength and ductility provided by the reinforcement and formwork, will lead to a lower-risk construction methodology for lunar settlements. In this paper, we present experimental data from flexural and tensile strength testing of a terrestrial concrete mix reinforced with prototype lattice reinforcement. These preliminary results show successful reduction in crack propagation relative to the unreinforced control specimens, though no increase in tensile or flexural strength. Additional work is necessary to study whether tuning the geometry of the reinforcement or the concrete/lattice interface could realize increases in strength in addition to crack propagation reduction, especially with lunar simulant mixes.