Autogenous Self-healing of Cracked Concrete – Modelling of Reactive Transport

• Applicant: Professorin Dr.-Ing. Sylvia Keßler
• Subject Area: Construction Material Sciences, Chemistry, Building Physics
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 563941058

During the curing process of concrete structures, the dissipation of hydration heat can generate tensile stresses that exceed the tensile strength of young concrete, leading to the formation of separation cracks. This phenomenon, known as early-age cracking, compromises the functionality and durability of structures, as cracks create pathways for water and aggressive chemical substances, which accelerate the deterioration of reinforcement steel and concrete. In water-retaining concrete structures such as basement walls, tunnel linings, and water silos—where groundwater or water is retained on one side and cracks are exposed to hydraulic gradients—the phenomenon of autogenous self-healing can promote crack closure. This self-healing effect has the potential to restore the functionality and durability of such structures. Eurocode 1992-3 acknowledges this and permits civil engineers to account for autogenous self-healing in cracks ≤ 200 µm in water-retaining concrete structures, provided specific hydraulic conditions are met. However, inconsistent healing efficiency observed in practice, even under these conditions, indicates that the processes governing autogenous self-healing and their implications for construction practices are not yet fully understood and require further investigation. A thorough literature review identifies the following key research gaps: (i) It remains controversial whether the portlandite content in the cement matrix limits autogenous self-healing through CaCO₃ precipitation. (ii) Current conceptual models of reactive transport through cracked concrete lack empirical validation and fail to account for the time-dependent nature of self-healing. (iii) There is no spatial data on the location and quantity of CaCO₃ precipitation along the crack path. (iv) The experimental results that supported the inclusion of autogenous self-healing in Eurocode 1992-3 have not been independently validated. To address these gaps, the primary objective of this proposal is to develop a chemical and mineralogical model of autogenous self-healing, validated through experimental data, with a focus on reactive transport through cracked concrete. This approach aims to replicate and validate previous findings, providing a robust framework for predicting self-healing behavior. Ultimately, this research seeks to enable reliable predictions of autogenous self-healing, enhancing the durability of concrete structures and reducing the environmental footprint of the construction sector.

• DFG Programme: Research Grants