Study of the Micromechanical Properties and Dissolution Characteristics of Porous Coral Reef Limestone

This study investigates the fundamental properties of shallow aragonite-component dominant porous coral reef limestone (CRL) to investigate its micromechanical properties and micrometer-scale pore dissolution characteristics. Nanoindentation tests were performed to assess changes in mechanical properties before and after dissolution. A novel numerical model, integrating the level-set method (LSM), reactive-transport modeling, and image processing technology (IPT) was developed to simulate the static dissolution process of a computed tomography (CT)-scanned porous CRL structure. The nanoindentation results showed that after dissolution, the Young's modulus (E) of the primary mineral component aragonite decreased from 34.09 to 30.01 GPa. Numerical simulations further explored the effects of temperature and mineral component on the dissolution characteristics of CRL. In the multicomponent CRL structure, where both aragonite and calcite coexist, selective dissolution occurred, with aragonite inhibiting calcite dissolution and altering the dissolution pathway. Conversely, the monocomponent aragonite structure was more susceptible to forming larger pores during dissolution. Meanwhile, the dissolution volume and porosity increased with temperature, rising by 47% and 4.84%, respectively, whereas the variation in pore radius did not exhibit a consistent trend with increasing temperature. The macroscopic E was estimated using both the Mori-Tanaka approach and simulation methods, demonstrating that pore dissolution weakens the macromechanical properties of the CRL. This comprehensive analysis enhances the understanding of the physical and chemical properties of CRL, providing valuable insights for the safe and stable construction of islands and reefs.