GRC-3b-DST, a Geotechnical Simulant for Cohesive Mars and Moon Mobility and Excavation Testing With Reduced Respirable Silica

This study presents the development and evaluation of a modified version of the GRC-3b lunar soil simulant designed to address both geotechnical performance and operator safety in terrestrial mobility and excavation testing. While GRC-3b is widely used due to its cost-effectiveness and similarity to extraterrestrial regolith, its fine silica content poses significant health risks during handling. To mitigate this, a dust-suppressing additive was introduced, producing GRC-3b-DST. The modified simulant maintained the original particle size distribution and classification as a well-graded silty sand but exhibited increased cohesion and a lower minimum density, enhancing its ability to replicate compacted regolith conditions. Laboratory testing, including modified Proctor compaction, simple shear tests, and cone penetrometer correlations, confirmed that the geotechnical properties of GRC-3b-DST are consistent and predictable, making it suitable for high-fidelity terrain simulations. Safety testing using OSHA-compliant air sampling showed respirable silica concentrations remained well below permissible exposure limits during soil preparation, indicating a significant reduction in airborne hazards. These findings suggest that GRC-3b-DST offers a safer, more versatile alternative for use in large-scale test environments where repeatable geomechanical properties and minimized health risks are essential.