Reactive transport modelling of autogenous self-healing in cracked concrete

Autogenous self-healing can close cracks in water-retaining concrete structures. However, its inconsistent efficiency in building practice indicates that the underlying processes are not fully understood. Therefore, this study characterizes reactive transport through cracked concrete and models it using PHREEQC to develop a comprehensive understanding of chemical processes promoting autogenous self-healing. Driven by the dissolution of portlandite, the main cause of healing is the precipitation of CaCO₃, which contributes to a crack closure of up to 113 μm. This process is supported by the formation of M-S-H and C-S-H. As self-healing progresses, the rates of dissolution and precipitation processes that promote healing decrease exponentially. At initial flow rates >2 L h⁻¹, CaCO₃ precipitation is favored towards the crack outlet. At lower initial flow rates, the formation of CaCO₃ shifts towards the crack inlet. These findings underscore the need to reconsider the reliance on effective healing in practical applications.