Suitability of Split Box Direct Tension Testing for Measuring Tensile Strength of Regolith Simulants

Under low effective stress conditions, the often-neglected soil tensile strength may significantly influence the behavior of lunar and Martian regoliths. Therefore, regoliths' tensile strength in extraterrestrial environments may pose many challenges for future space operations and exploration such as in situ resource utilization (ISRU). To explore regolith tensile strength for physical modeling on Earth, this study assessed the efficacy of the split box direct tension test method in measuring small amounts of tensile strength of F-75 Ottawa sand with added crystalline silica powder (CSP) at 30% and 50% by weight, and more commonly used lunar simulants JSC-1A and GRC-3. Findings indicate an increase in tensile strength with increasing regolith density. However, JSC-1A and GRC-3 forced open the split box prior to applied loading at low relative densities. This highlights the importance of considering system friction and lateral forces in the specimen during analysis. Although split box testing provided reasonable estimates of tensile strength, the testing method is more appropriate for soils with significantly greater tensile strengths than those tested here.