Effect of enzyme-induced calcium carbonate precipitation on mechanical properties and microstructure of 3D printed sandstone-like specimens

3D printing technology has demonstrated broad application prospects in rock laboratory experiments due to its advantages such as rapid prototyping and complex structure reproduction. However, the poor mechanical properties of printed specimens limit their practical engineering applications. To effectively enhance the mechanical properties of 3D printed sandstone-like specimens, this study employed GS19 type sand and furan resin-based sandstone-like specimens as research objects. Specimens were treated with different cycles of enzyme-induced calcium carbonate precipitation (EICP) solution infiltration. The evolution of mechanical properties was quantitatively analyzed through uniaxial compression tests, while scanning electron microscopy-energy dispersive spectroscopy and Fourier transform infrared spectroscopy were used to reveal the mechanical enhancement mechanism of EICP technology at microscopic scale. Results indicate that the compressive strength and elastic modulus of the specimens progressively increased with infiltration cycles. After four EICP solution treatments, the specimen strength increased by 51.92% and the elastic modulus increased by 35.57% compared to the control group, with failure modes and crack propagation characteristics resembling those of natural weakly cemented sandstone. Microscopic analysis revealed that EICP technology promoted the formation of “resin-calcium carbonate” composite cementation phases within specimens. This dual mechanism of enhancing intergranular cementation strength and pore-filling to reduce structural defects significantly improved mechanical performance. The findings expand the application potential of 3D printing technology in rock experimentation.