Optimizing Magnesium Phosphate Binders with Boric Acid for Additive Construction Applications

The authors are proposing a comprehensive research approach and terminology for providing a framework to utilize an ordinary portland cement (OPC) alternative class of materials for both extraterrestrial habitats and terrestrial 3D construction applications, where sand and clay can replace regolith. Magnesia-based binders (MBBs) have shown a great promise for use in different additive construction (AC) applications due to its superior properties such as high compressive strength, rapid setting time, and excellent durability, in addition to the possibility of harvesting these binders from lunar and Martian regolith. Our primary objective in this research is to prove the concept of utilizing magnesia phosphate cement (MPC) composites with different additives, including boric acid, graphene nanoplatelets (GnP), acetic acid, and potentially Martian and lunar regolith simulants as a potential construction material for the planetary habitation exploration missions. Before adjusting the mix design properties required to meet specific 3D construction printing needs, several aspects must be studied in depth to provide a better understanding of the MPC paste and composite behavior. This work aims to give more insight into the relative physical, mechanical, thermal, and chemical performance of the MPC pastes with varying additions of boric acid. The experimental results show that boric acid can change the phase compositions of the MPC paste and affect its performance. It can improve the initial setting time of the paste and alter the structure of its binding products. Finally, our proposed research creatively utilizes artificial neural networks (ANN) to investigate and subsequently optimize both the MPC pastes and composite formulation for real-time adjusting of 3D printing processes based on the desired material performance criteria.