Temperature-dependent mechanical properties and crack propagation modes of 3D printed sandstones

Abstract

We aim to investigate the mechanical properties and crack propagation modes of 3D printed sandstone after high temperature, focusing on the alteration of furan resin during heating. Unlike the most current printed sandstone studies that are conducted at room temperature, we attempt to explore the performance of the heated printed sandstone, dominated by the furan resin. The heated 3D sandstones are investigated with a series of sophisticated in-door experiments at macro, meso, and microscopic levels. It is found that the uniaxial compressive strength and splitting tensile strength of the printed sandstones reached the maximum of 150 °C, at which the furan resin transforms from solid to liquid state, enabling to bond more sand particles. This is followed by the studies of crack propagation patterns and mechanical properties of heated specimens, where man-made cracks of different inclination angles are prefabricated and uniaxial compressive strengths are conducted. The results indicated that the peak strength of the cracked specimens first decreases and then increases with the increases of cracks inclination angle after heating. Furthermore, an X-ray computed tomography image is constructed, showing the difference between the internal fracture and the apparent fracture of the specimen. Our above findings show that these well-fabricated and easy-to-observing printed specimens could, to some extent, reflect heated natural sandstone behaviours, such as strength, crack initiation, and propagation. Nevertheless, when heated to 300 °C, the furan resin is becoming further dehydrated, almost losing its bonding capability and so the printed sandstone's initial structure could not be maintained any longer.