Microstructure and mechanical behavior of 3D printed rock-like specimens based on different post-processing methods

3D printing technology offers a unique advantage in fabricating rock specimens with precise internal defects. However, the low strength and stiffness of sand-type 3D printed samples limit their application in rock mechanics. This study primarily focuses on the microstructural characteristics of the specimens, including changes in pore structure, cementing materials, and brittleness properties. Three distinct post-processing methods were employed to explore effective approaches for enhancing the strength of specimens while preserving their desired brittleness. The findings indicate that infiltration treatment significantly reduces the porosity of the specimens and increases the roughness of particle surfaces. In contrast, freezing treatment slightly decreases the porosity and augments the roughness of particle surfaces. Moreover, while the specimens treated only with infiltration exhibited noticeable plasticity, those subjected to both permeation and freezing showed marked brittleness. Furthermore, specimens treated solely with infiltration experienced a modest increase in strength and displayed noticeable plasticity, whereas combined treatment of infiltration and freezing resulted in a substantial increase in strength and conspicuous brittleness. Additionally, the mechanical properties, failure modes, and fracture surface microstructure of the combined-treated specimens resemble those of natural granite. These findings offer solutions for addressing the low strength and stiffness of sand-type 3D printed rock-like specimens.