Calcium carbonate formation mechanism in MSHC revealed by molecular simulation

ABSTRACT

Microbial self-healing concrete (MSHC) is an eco-friendly material that supports low-carbon development. However, the formation mechanism of calcium carbonate (CaCO₃) in MSHC remains unclear. This study investigated the formation process of CaCO₃ clusters in MSHC using molecular simulation. The hydroxide ion and carbonate ion (CO₃²⁻) would compete for association with calcium ion in MSHC. The formation process of CaCO₃ clusters could be summarised as follows: free ions first associated to form ion pairs, then ion pairs aggregated into small clusters through ion-dipole interactions, and finally, small clusters overcame the surface charge effect by high-frequency aggregation-separation behaviour to transform into large clusters and further densify themselves. The reaction rate of CaCO₃ cluster formation decreased significantly with the decrease of CO₃²⁻ concentration, and the association between calcium ion and hydroxide ion would dominate when the CO₃²⁻ concentration was low.

KEYWORDS:

• Microbial self-healing concrete
• calcium carbonate
• hydroxide ion
• quantum chemical
• molecular dynamics

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Jinling Institute of Technology [grant number jit-b-202359]; Fundamental Research Funds for the Central Universities [grant number B230201060]; JSTI Group [grant number 22880050-D01-001, 823088816].