Martian habitats are ideally constructed using only locally available soils; extant attempts to process structural materials on Mars, however, generally require additives or calcination. In this work we demonstrate that Martian soil simulant Mars-1a can be directly compressed at ambient into a strong solid without additives, highlighting a possible aspect of complete Martian in-situ resource utilization. Flexural strength of the compact is not only determined by the compaction pressure but also significantly influenced by the lateral boundary condition of processing loading. The compression loading can be applied either quasi-statically or through impact. Nanoparticulate iron oxide (npOx), commonly detected in Martian regolith, is identified as the bonding agent. Gas permeability of compacted samples was measured to be on the order of 10−16 m2, close to that of solid rocks. The compaction procedure is adaptive to additive manufacturing.

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An inorganic-organic hybrid (IOH) of silica particulates and polyethylene (PE) was investigated, where silica was employed as an analogue to lunar soil. The objective was to search for the optimum materials design strategy for " lunar cements " -infrastructural materials based on locally harvestable resources on the Moon. If the silica particulate size was uniform, the flexure strength of the IOH decreased quite linearly with the PE content. With a two-step size gradation of silica particulates, the flexure strength of the silica-PE IOH could be much improved, higher than that of Portland cements with only 4 wt% of PE. A threshold PE content around 6 wt% existed. Above the threshold, the PE content has only a secondary effect on the IOH flexure strength; below the threshold, the IOH flexure strength decreases abruptly. In order to further enhance the IOH strength and to reduce the binder content, this threshold value must be minimized.

Inorganic-organic hybrid (IOH) lunar cements are processed by using a lunar soil simulant and polyethylene (PE). As the inorganic simulant grains are strongly held together by the PE binder, the IOH may be utilized as an infrastructural material on the lunar surface. With a uniform simulant grain size, the flexural strength of the IOH decreases exponentially with the binder content, quite close to the strength of samples of random simulant grain-size distribution. If the simulant grains have a two-step size gradation, the IOH strength increases significantly. Above a threshold binder content, the strength decreases only slightly as more simulant grains are added; below the threshold, the IOH becomes much weaker as less binder is used.

In order to minimize the binder content in composite lunar "cement," this paper uses JSC-1A lunar soil simulant and unsaturated polyester resin (UPR) to produce low-binder-content composite. Important system parameters such as compression pressure, compression duration, vibration, loading rate, loading number, and initial grain size distribution are analyzed. The most critical control variable is the compression pressure: at ∼350 MPa, the binder content is reduced to 6.5-8.7% by weight and the flexural strength is approximately 30-40 MPa. This research is important for in situ resource utilization for future lunar base construction and expansion. ASCE 06017013-1 J. Mater. Civ. Eng. J. Mater. Civ. Eng., 2017, 29(10): 06017013 Downloaded from ascelibrary.org by University of California, San Diego on 09/12/17. Copyright ASCE. For personal use only; all rights reserved. © ASCE 06017013-3 J. Mater. Civ. Eng. J. Mater. Civ. Eng., 2017, 29(10): 06017013 Downloaded from ascelibrary.org by University of California, San Diego on 09/12/17.

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We report the experimental results of fatigue behavior of ultralow-binder-content inorganic-organic hybrid (IOH) based on lunar soil simulant, which may be viewed as a “lunar cement”. Under the same loading condition, the fatigue life of the IOH is superior to typical steel-reinforced concrete, especially when the stress amplitude is relatively high. Fatigue damage mostly occurs in the binder phase, followed by rapid cleavage-like failure. The important material parameters include filler type, filler particle size, and filler-binder bonding.