Toward accurate rheological prediction of lunar regolith simulant pastes via constitutive modeling

Abstract The colonization of other worlds has been a long-standing desire of humankind. This has yet to occur due to several challenges, one of which is the difficulty of transporting building materials from Earth to the intended extraterrestrial site. Inevitably, the utilization of in situ resources, such as regolith for habitat construction, is crucial to the sustainability of extraterrestrial exploration. In this work, we employ a recently developed constitutive rheological model, using non-equilibrium thermodynamics, that can accurately predict the rheological response of lunar regolith simulant and alkaline solution pastes, which behave like cementitious-like pastes using a chemical reaction known as geopolymerization. The model has been carefully calibrated using experimental data from the literature for three temperatures and two water-to-binder ratio values. A key advantage of the current rheological model over the traditional phenomenological models commonly used to predict the response of lunar regolith simulant pastes, such as the Bingham and Herschel–Bulkley models, is its capacity to predict normal stresses. As this is the first rheological model of its kind, we expect it to be highly valuable for future additive manufacturing (3D printing) simulations, particularly as additive manufacturing gradually becomes the preferred method for constructing extraterrestrial habitats.