Creation of the Largest Uniform Microwave-Sintered Lunar Regolith Simulant Bricks

The Moon’s discovery of essential resources like water ice has once again piqued interest in its potential as a long-term hub for space exploration. NASA's Artemis mission, aimed at establishing a permanent human settlement on the lunar surface, further highlights this vision. However, developing vital infrastructure, such as lunar habitats, is pivotal to this goal.

Transporting construction materials from Earth to the Moon, however, is not economically feasible. The estimated cost for delivering materials via landers is a staggering 1.2 million USD per kilogram. Thus, the immense weight of building materials makes shipping them from Earth to the lunar surface virtually impractical.

In response to this challenge, the Korea Institute of Civil Engineering and Building Technology (KICT), under the leadership of President Kim, Byung-Suk, has pioneered a method to create construction materials using the moon's in-situ resources.

The Moon’s regolith, its surface soil, is one of the most abundant in-situ resources. Using this material for construction could result in substantial cost reductions. Composed of fine particles, lunar regolith can be sintered using heat. But under space conditions, energy consumption must be optimized—making microwave heating an ideal solution given its superior energy efficiency.

The research team, led by Dr. Hyu-Soung Shin and including Dr. Jangguen Lee, Dr. Young-Jae Kim, and Dr. Hyunwoo Jin, from the Future & Smart Construction Research Division at KICT, leveraged microwave sintering to transform lunar regolith simulant into solid blocks by applying heat and pressure.

When microwaving lunar regolith, areas of uneven heating, known as hot and cold spots, can emerge. These inconsistencies result in localized thermal instability, compromising the sintering process. To combat this, the team developed a staged heating program, fine-tuning temperature and dwell times. Additionally, volatile compounds, including water, in the regolith can trigger cracks during heating. The team prevented such cracking by preheating the lunar regolith simulant to 250°C under vacuum conditions.

The durability and consistency of these sintered blocks were assessed by core-drilling them at key points. The average density, porosity, and compressive strength of these samples were about 2.11 g/cm³, 29.23%, and 13.66 MPa, respectively. The relatively minor variations—0.03, 1.01, and 1.76—demonstrate the homogeneity of the blocks.

KICT has succeeded in securing this innovative technology to produce construction materials using lunar regolith. They now aim to test this technology in actual space conditions. By validating it in space, they hope to meet the growing need for advanced space construction solutions.

Dr. Shin stated, “Previous attempts at microwave sintering in space construction research have often resulted in either small or unevenly sintered structures.” He added that the team is looking forward to applying this technology to various infrastructure projects on the Moon's surface in the future.

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The Korea Institute of Civil Engineering and Building Technology, backed by 41 years of government-driven research, leads efforts to tackle pressing national challenges directly affecting the nation’s quality of life.

This research was conducted under the KICT Research Program (project no. 20230081-001 & 20240184-001, Development of Environmental Simulator and Advanced Construction Technologies over TRL6 in Extreme Conditions), funded by the Ministry of Science and ICT. The team’s findings were published in Journal of Building Engineering, a leading international journal in civil engineering (Impact Factor 6.4).

Journal

Journal of Building Engineering

DOI

10.1016/j.jobe.2024.109193

Article Title

Optimized Manufacturing Process of Homogeneous Microwave-Sintered Blocks of KLS-1 Lunar Regolith Simulant

Article Publication Date

1-Jul-2024