Improving structure properties of Jinsha relic ancient ivory by microbial-induced carbonate precipitation

The waterlogged ivory relics excavated from the Jinsha site exhibit structural damage and reduced toughness due to burial-induced organic matter decomposition. Therefore, this study employed microbial-induced carbonate precipitation (MICP) to treat waterlogged ivory samples via Sporosarcina pasteurii with a urease enzyme activity of 59.5 U and carbonic anhydrase enzyme activity of 0.34 U. X-ray computed tomography (CT) analysis revealed that calcium carbonate crystals generated through MICP effectively filled pores, reducing total pore volume by 46.7%. Specifically, the microporosity volume and specific surface area of the 1–60 nm pores were reduced by 50.9% and 57.6%, respectively. X-Ray diffraction (XRD) analysis confirmed that the calcium carbonate crystals produced by MICP were calcite and vaterite. In addition, the MICP-treated ivory exhibited a compressive strength of 20.38 MPa, 3.3 times higher than that of untreated samples. These results demonstrated that MICP can effectively strengthen excavated waterlogged ivory.