Abstract For later-stage construction on the Moon and Mars utilizing in-situ resources, a key unresolved question is whether the cohesionless and edgy surface soil (regolith) can act as a reactive cementitious material or as an inert filler. This study presents a multimodal reactivity assessment of lunar and Martian regolith simulants to evaluate their potential as active binders or fillers in cement-based systems. Six simulants were investigated in untreated, burned, and milled conditions, and a total of 18 blended mixtures were prepared with OPC. All untreated simulants exhibited negligible heat release in both water and potassium hydroxide solutions, indicating non-reactive behavior. Thermal and mechanical processing did not produce meaningful increases in reactivity, with cumulative heating remaining below known thresholds associated with hydraulic or pozzolanic materials. Conductivity measurements confirmed non-pozzolanic behavior for lunar simulants, while Martian simulants showed apparent ionic depletion, suggesting non-pozzolanic mechanisms in calcium hydroxide environments. Blend mixtures displayed similar hydration kinetics and cumulative heat (100–150 J g⁻¹), with no enhancement in portlandite consumption. Compressive strengths of blended systems ranged from 11.2 to 29.8 MPa, confirming that regolith primarily functions as an inert filler. These findings establish a practical baseline for extraterrestrial construction strategies based on in-situ resource utilization.
Leon-Miquel et al. (Fri,) studied this question.