Regolith Stabilization and Building Materials for the Lunar Surface

During lunar exploration, regolith is both the major available resource and a substantial obstacle in establishing a long term presence. The fine surface dust is highly abrasive and can both be a health hazard for the crew and the main contributor to equipment failure. On the other hand, regolith is the only material readily available to build protective shelters, stabilize slopes, form roads or engineer landing pads. To achieve this, methods had to be developed to convert regolith into a stable building material with minimal need for terrestrial supplies The approach described in this paper uses urethane resins to produce concrete-like materials on the lunar surface from minimal earth-supplied materials. The binder had to be capable of wetting regolith material both for optimal consolidation into bricks and to allow spray application for road formation. At the same time the resin had to have a very low vapor pressure to avoid contamination of the environment via outgassing. The program optimized a urethane formulation capable of penetrating and binding dense lunar surface particles under conditions consistent with the lunar surface. The urethane was capable of agglomerating lunar surface material into densely packed blocks capable of acting as a building material at a 20:1 regolith to binder ratio. The blocks were sufficiently strong to act as structural members of a habitat designed to shield inhabitants from dangerous solar radiation events. The blocks were tested for mechanical stress to ensure that their strength would not preclude their use in wall and habitat construction. Compression strength values of over 1000 psi were achieved. A prototype brickmaker to fabricate building blocks without exposure of personnel or moving parts to the mixed resin was designed and built, along with an automated spray system for surface stabilization.