Effects of Curing Conditions on Material Properties of BP-1 Lunar Regolith Simulant Geopolymer Binders


  • Jake George, Chemical Engineering, University of Delaware

Faculty Mentor(s)

  • Norman Wagner, Department of Chemical and Biomolecular Engineering, University of Delaware
  • Ted Egnaczyk, Department of Chemical and Biomolecular Engineering, University of Delaware


NASA’s upcoming Artemis missions in the current decade demand high-strength construction materials optimized for the lunar surface. Utilizing geopolymer cements produced via in-situ resource utilization (ISRU) of local lunar regolith shows promise for creating lunar construction materials with minimal payload requirements. Geopolymer binders are formed via a water-neutral reaction and are often studied for terrestrial applications as sustainable alternatives to cement. Previous work has investigated the geopolymerization of several lunar regolith simulants and assessed the impact of varying aluminosilicate chemistry on the compressive strength (CS) of ambiently cured geopolymer binders formed from Black Point 1 (BP-1) lunar regolith simulant. The goal of the current study is to develop an optimal curing protocol for the lunar surface, producing a geopolymer with high compressive strength under vacuum curing conditions. Two curing methods were evaluated initially at ambient conditions: (1) elevated temperature and (2) microwave irradiation (MW). Two curing temperatures (100 and 200 C), heating duration, and microwave power were varied to develop an optimal protocol, with supporting characterization of both water loss during cure and the geopolymer pore structure via X-Ray tomography post cure. The highest strength ambiently cured BP-1 geopolymer (15.5 MPa) was achieved through MW curing at 300 Watts for 10 minutes. This optimal protocol was further applied to geopolymers cured under vacuum to simulate the lunar environment. Surprisingly, vacuum-cured BP-1 geopolymers exhibited a high CS of 18.5 MPa just one day after initial reaction, far surpassing the seven-day CS without additional treatment (1.5 MPa). X-ray tomography revealed distinct differences in porosity based on the curing method, providing information on internal structure. This study highlights the impact of curing protocols on material properties of lunar regolith simulant geopolymer binders, informing future development of lunar construction materials.