Regulatory Mechanism of Reactive MgO on Microbial Mineralization in Concrete Self‐Healing

ABSTRACT

To tackle the durability degradation caused by concrete cracks and overcome the limitations of traditional post‐crack repair methods, this study integrates reactive MgO with microbial‐induced carbonate precipitation (MICP) technology. By analyzing the synergistic mineralization effects of MgO under varying environmental factors, the regulatory mechanisms of bio‐mineralization in crack self‐healing were systematically investigated. Compared to heavy‐calcined MgO, light‐calcined MgO exhibited higher reactivity, significantly increasing hydromagnesite production. At pH 12, the generation of CO ₂ from bio‐precipitations after pickling reached 0.575 g (as carbonate equivalent). The presence of Mg ²⁺ notably enhanced microbial metabolic activity (maximum OD ₆₀₀ over 2.38), which can mitigate the inhibitory of strong alkalinity on bacterial proliferation in crack zone. Elevated temperatures improved hydromagnesite crystallinity and cementation strength. Sodium‐containing polysaccharides (SP), with carboxyl groups and long‐chain structures, facilitated the formation of hydrated magnesium carbonate by complexing and sustained‐release Mg ²⁺ . When the concentration of SP is 1.2 g/L, the production of carbonate minerals peaked, increasing by 25.74%. Furthermore, Ca ²⁺ leaching from concrete cracks further stimulated the bio‐mineralization of magnesium‐based materials, enhancing carbonate production by 27.13%–44.7%. These results validated the environmental adaptability and application potential of reactive MgO–MICP technology in concrete crack self‐healing, providing theoretical support for optimizing low‐carbon self‐healing concrete.