Several space agencies worldwide intend to establish long-term lunar habitations in the future. The study of building materials that may be optimally utilized for moonbases is a very active field of research, with activities mainly focusing on the use of locally available lunar regolith in the frame of In-Situ Resource Utilization (ISRU). The purpose of this research was to investigate lunar regolith simulants utilized as filler material in rigid polyurethane (PUR) foams, with the goal of producing a composite building material that may be beneficially used for lunar habitats.

In the frame of our work, different PUR foam / lunar regolith simulant composite materials were created with variable parameters, like the polyurethane foam matrix density, lunar regolith simulant grain size, concentration and the mixing method. Unfilled reference foams were likewise synthesized and investigated for comparison purposes. Characterization methods included mechanical compressive strength test before and after exposure to UV light. Basic parameters of the foaming process like reaction temperature and foaming time were also measured. Pore structure, density and regolith distribution were studied with Scanning Electron Microscopy.

Compressive strength decreased due to UV light exposure for unfilled polyurethane foams. However, the addition of lunar regolith simulant with the proper parameters improved the material's UV resistance. In general, the effect of regolith reinforcement were very sensitive to the mixing method, particle size distribution and matrix density.

This work will be continued by the investigation of various material characteristics in the function of technological parameters and gravity level, including an experiment on board of the ISS to study the effect of microgravity on the foaming process. ISS experiments will be performed in the frame of the Hungarian to Orbit (HUNOR) program (Ministry of Foreign Affairs and Trade of Hungary).