Previous studies have investigated static cracks and pores before and after compressive tests of 3D-printed (3DP) rock with limitations in describing real-time cracking and damage evolution during compression. In this study, compression tests were conducted on 3DP gypsum rocks using an in-situ micro-computed tomography (micro-CT) system to obtain 2D CT images during compression. Through 3D reconstruction of 2D CT images, crack propagation and pore evolution of 3DP gypsum rocks could be illustrated from a 3D stereoscopic perspective and quantitatively analyzed. Results indicated that multiple tensile cracks propagated along the axial direction during compression. Initially, the volume of 3DP gypsum rocks decreased owing to pore closure during the compaction stage in which cracks were yet to be initiated. As the external stress exceeded the bearing capacity of 3DP gypsum rocks, the crack volume increased first marginally and then rapidly as cracks initiated and further developed with the increased stress.
Three-dimensional (3D) printing is an emerging technology that has garnered increasing interest in the rock mechanics community as it is controllable, repeatable, accurate, efficient, time-saving, and economical (Fereshtenejad & Song 2016, Ishutov 2019 and Kong et al. 2021). It allows researchers to prepare identical specimens, replicate complex structures, and visualize the interior of intact rocks, creating new possibilities for understanding rock mechanics (Gao et al. 2021, Jiang & Zhao 2015 and Ju et al. 2014). Various mechanical tests have been conducted on 3DP rock-like samples using various printing materials—including resin, acrylonitrile butadiene styrene, polylactic acid, cement, gypsum, and sand powder—to examine whether 3D printing technology can be applied to rock mechanics (Fereshtenejad & Song 2016, Ishutov 2019, Kong et al. 2021, Gao et al. 2021, Jiang & Zhao 2015, Ju et al. 2014, Song et al. 2022 and Zhu et al. 2018).
X-ray micro-computed tomography (micro-CT) is an effective nondestructive method for identifying and visualizing the interior structures of rocks in 3D. In several rock-engineering studies, this technique has been used to analyze the microstructural properties and the extent of damage in natural rocks (Yao et al. 2009 and Duliu 1999). By combining 3D printing and micro-CT technologies, high-precision results can be obtained with repeated sample preparation of natural rocks (Zhu et al. 2018 and Song et al. 2022), and the pore structure and crack morphology of 3DP samples can also be analyzed and quantified (Kong et al. 2018 and Zhu et al. 2018). However, only a few studies have investigated the crack propagation and pore evolution of 3DP rock-like samples under compressive tests using in-situ micro-CT technology, which is essential for characterizing and understanding the failure mechanism and microstructural evolution of 3DP rock-like samples for modeling natural rock behavior.
