Microscopic and macroscopic failure of sintered glass beads: mechanisms and relevance for sandstone surrogates

Cemented granular materials (CGMs) include ceramics, concrete, sandstone, and other sedimentary rocks. These materials have prominent roles in geophysics, engineering, and defense applications. However, due to their microstructural complexity, a complete understanding of the microscopic mechanisms governing macroscopic mechanical behavior in natural CGMs such as sandstone and sedimentary rocks is still lacking. This has motivated the development of surrogate, engineered CGMs, such as sintered glass beads, which permit simultaneous control of multiple microstructural properties such as grain size and porosity. In this presentation, we examine sintered soda-lime glass at the microscale and the macroscale to study deformation mechanisms and test their viability as sandstone surrogates with controlled porosity and grain size. Using a variety of sintering protocols, inter-particle bond tensile testing at the microscale, and unconfined uniaxial compression testing at the macroscale, we found that: (1) inter-particle bonds featured pores similar to those observed in sedimentary rocks; (2) inter-particle bonds exhibited a statistical size effect on strength, with failures nucleating at pores; (3) sintered soda-lime glass cylinders featured unconfined compressive strength comparable to porosity-matched sandstones and followed trends predicted by strength models developed in the rock physics and sintering literature. These results support using sintered soda-lime glass as a sandstone surrogate and elucidate new aspects of their micromechanics, including bond failure mechanisms and statistical size effects.