Optimization of Alkali-Activated Regolith Simulants for Lunar Construction by 3D Printing (2026-01)¶

The key to a sustainable presence in space is the ability to manufacture structures and spare parts on-site. This approachreduces costs and limitations on what can be launched for long missions. Future habitation on the Moon and Mars will depend on utilizing local resources to create building materials that meet infrastructure needs while ensuring environmental safety. Alkali-activated materials (AAMs) have emerged as a viable alternative to traditional binders, gaining attention for their environmental advantages. However, there remains a significant gap in understanding their fresh properties. This article investigates the feasibility of producing construction materials from lunar regolith simulants by analyzing the rheological behavior of AAMs derived from LMS lunar regolith simulant. The study focuses on lunar regolith simulants mixtures activated with sodium silicate and sodium hydroxide solutions, examining how factors such as the liquid-to-solid ratio (Li/So), silica modulus (SiO₂/Na₂O), metakaolin substitution (Mk), and curing temperature (T) influence their properties. First, ANOVA confirms the high significance of the model, as indicated by the Fisher statistical test at a 99% confidence level. Furthermore, the model’s coefficient of determination (R2 = 0.8967) demonstrates strong compatibility, accounting for 89.67% of the variation in yield stress. Additionally, results show that increasing metakaolin content and curing temperature significantly enhances yield stress, attributed to microstructural changes and increased cross-linking. Yield stress ranges from 6.5 to 63.4 Pa under optimal conditions, specifically at 20 °C, a liquid-to-solid ratio of 0.4 to 0.41, metakaolin content between 0% and 15%, and silica modulus values between 0.8 and 1.6.