Comprehensive microscopic mesoscopic and macroscopic evaluation of 3D-printed furan-resin bonded quartz sand specimens for physical simulation of the material and mechanical properties of natural weakly cemented sandstone

During coal mining the mechanical behavior of weakly cemented sandstone in roof or interbedded layers is crucial for mine safety. In this study the physical and mechanical properties of 3D printed specimens made from furan resin bonded quartz sand were systematically evaluated. The aim was to achieve high fidelity simulation of natural weakly cemented sandstone from mineral composition to macroscopic mechanical behavior using a saleable, low-cost and post-processing-free manufacturing approach. Multi scale analyses at microscopic mesoscopic and macroscopic levels showed that the mineral composition and XRD diffraction patterns of the specimens closely matched those of natural sandstone. SEM and EDS characterization confirmed that the grain packing and cementation structures were highly similar to those of natural samples. The particle size distribution exhibited the typical log normal pattern seen in sedimentary rocks with both transgranular and intergranular fracture modes present. Mechanical tests including uniaxial compression Brazilian splitting and three-point bending indicated brittle failure characteristics with strengths and elastic moduli approaching those of natural weakly cemented sandstone and higher flexural tensile strength in the three point bending tests than in Brazilian split tests. Tests on specimens with joints successfully reproduced the U shaped variation of peak stress and elastic modulus with joint inclination as well as typical brittle fracture modes. High consistency in mechanical properties across batches further validated the stability and reliability of the 3D printing process. This method provides a precise controllable and low-cost new approach for the physical simulation and modeling of weakly cemented sandstone in mining engineering.