Lunar and Martian regolith simulants have been analyzed to assess their cementitious potential. Though the simulants exhibited little cementitious reactivity under tested conditions, they did show potential as inert fillers. These findings, published in npj Space Exploration, provide important guidance for future development of construction materials based on in situ resources for future Martian and lunar habitats.
Study: Assessing the cementitious reactivity of lunar and Martian regolith simulants for extraterrestrial construction. Image Credit: muratart/Shutterstock.com
Understanding the Construction Potential of Planetary Regolith
Building permanent infrastructure on the Moon and Mars will require construction materials that are available on-site, as transporting cement from Earth is prohibitively expensive and impractical for large-scale construction. As a result, researchers are exploring ways to use planetary regolith as a local building material.
Regolith is the loose layer of rock fragments and mineral particles covering the Moon and Mars. Researchers have explored its use in geopolymers, concrete, and other cement-based materials, but its role in cement-based systems remains unclear.
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Existing studies have not established whether regolith actively participates in cement hydration or simply functions as an inert filler. This uncertainty affects binder selection, material processing, and construction strategies for future space missions. A reactive regolith could reduce the amount of binder that must be produced or transported from Earth.
In this study, the researchers evaluated six different widely studied lunar and Martian regolith simulants to determine their cementitious potential. They also explored whether thermal activation and mechanical grinding could improve their performance.
Finally, they assessed hydration behavior and compressive strength after incorporating the simulants into ordinary Portland cement (OPC). The study provides valuable guidance for designing future construction materials based on in situ resources.
Evaluating Regolith Using Multiple Reactivity Tests
The researchers selected six commercially available regolith simulants representing two lunar environments and four Martian geological settings. The lunar simulants represented highland and mare regions, while the Martian materials represented basaltic surfaces, hydrated clay deposits, polyhydrated sulfate deposits, and sediments from Jezero Crater.
They evaluated each simulant in its untreated state and after thermal activation and mechanical milling, creating 18 different material conditions for comparison.
The team employed various characterization techniques to assess cementitious and pozzolanic reactivity. Isothermal calorimetry measured the heat released during hydration in water and potassium hydroxide solutions, providing evidence of hydraulic activity.
The researchers also performed particle-size analysis, thermogravimetric analysis, and chemical characterization to determine how thermal and mechanical processing influenced the material properties.
The researchers then prepared blended cement mixtures by replacing part of the OPC with untreated, burned, or milled regolith simulants. They monitored hydration kinetics using calorimetry and measured compressive strength after 28 days of curing.
By combining hydration and mechanical data, they determined whether the simulants actively contributed to strength development or primarily functioned as inert fillers within the cement matrix.
Limited Cementitious Activity Shapes the Role of Regolith
The study showed that all untreated lunar and Martian regolith simulants had very limited cementitious reactivity.
Heat released during hydration remained well below the levels expected for hydraulic or pozzolanic materials. Electrical conductivity tests also confirmed that the lunar simulants did not react with calcium hydroxide as conventional supplementary cementitious materials do.
Together, these results show that the tested regoliths do not actively participate in cement hydration under the conditions investigated.
The researchers then examined whether thermal activation or mechanical milling could improve reactivity. Both treatments produced small increases in cumulative heat release, particularly after milling.
However, the improvements remained far below the accepted threshold for reactive supplementary cementitious materials. These findings indicate that moderate heating below 1000 °C and short-duration milling do not significantly improve the cementitious behavior of the tested simulants.
Although the simulants showed little chemical reactivity, they still performed well as fillers in cement-based systems. The blended mixtures followed hydration patterns similar to OPC, indicating that the regolith did not disrupt cement hydration. Compressive strengths ranged from 11.2 to 29.8 MPa, depending on the simulant and processing method.
The researchers also highlighted important limitations, such as the fact that Earth-based simulants cannot fully reproduce the mineralogy, radiation history, and surface chemistry of actual lunar and Martian regolith.
In addition, the experiments were conducted under terrestrial laboratory conditions rather than the vacuum, reduced gravity, radiation exposure, and extreme temperature fluctuations found on planetary surfaces. These factors could influence the behavior of actual regolith and the researchers suggest this should be investigated in future studies.
Supporting Future Construction Beyond Earth
This study provides one of the most comprehensive evaluations of the cementitious behavior of lunar and Martian regolith simulants. The findings show that these materials function primarily as inert fillers rather than reactive binders under the conditions investigated.
Under the examined conditions, untreated regolith could not serve as a direct replacement for cement. However, it can still contribute to construction materials as a locally available filler. These insights will help engineers design more practical construction systems based on in situ resource use.
The study also identifies several opportunities for future research. Researchers should also evaluate tensile strength, shear resistance, fatigue behavior, and performance under repeated loading caused by moonquakes and Marsquakes.
Testing under reduced pressure, radiation exposure, and extreme thermal cycling will further improve understanding of how these materials perform in extraterrestrial environments.
Overall, the study establishes an important foundation for future space construction. It elucidates the role of untreated regolith in cement-based materials while identifying the processing strategies needed to improve its performance.
As in situ resource utilization technologies continue to advance, these findings may help support the development of durable, resource-efficient infrastructure for sustained human exploration of the Moon and Mars.
Journal Reference
Leon-Miquel, M., Byers, B. S., & Jin, Q. (2026). Assessing the cementitious reactivity of lunar and Martian regolith simulants for extraterrestrial construction. npj Space Exploration. 2(29). https://www.nature.com/articles/s44453-026-00047-8.
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