An improved sand 3D printing method for better reproduction of high-strength and high-brittleness rock mechanical properties is proposed

3D printing is an emerging technology which can provide valuable insights into the laboratory characterization and testing of rock mechanics. The binder jetting technology (BJT) process in 3D printing is one of the most promising tools for laboratory testing of rocks but still cannot reproduce high-strength and high-brittleness rocks. In this study, quartz sand and furan resin are chosen as the printing materials, and sand 3D printed rock-like specimens are used as the study objects. Based on this, the specimens are post treated, including vacuum infiltration with phenolic resin and high-temperature baking, and then these specimens are further subjected to uniaxial compression tests and Brazilian splitting tests to study their mechanical properties. A micromechanical explanation is given for the mechanical property enhancement using scanning electron microscopy (SEM) analysis and box-counting fractal dimension. The results show that the improved sand 3D printed rock-like specimens proposed in this study can reproduce the mechanical properties of high-strength and high-brittleness rocks in terms of the stress‒strain relationship, uniaxial compressive strength, elastic modulus, tensile strength and brittleness index. From the microstructure perspective, the mechanical properties are enhanced because of the improved micro-pore structure and increased bond strength between the particles. The micro-pore structure morphology of sand 3D printed specimens shows fractal characteristics, and the micro-pore pore area and the fractal dimension are positively correlated. The findings can support, to a certain extent, the future systematic investigation of the mechanical behavior of high-strength and high-brittleness rocks in underground engineering.