New classification, historical developments, technology readiness level and application conditions of self-healing concrete technologies

Self-healing concrete (SHC) enhances the longevity, sustainability, and durability of concrete structures by enabling automatic repair of damage. However, the conventional autogenous-autonomous classification struggles to accommodate the rapid advancements in sustainable concrete-binder systems and SHC technologies. This study introduces a novel classification framework under substance filling and mechanical closing that involve healing mechanisms, healing agents, and delivery methods, with the view to provide a more comprehensive approach to categorizing SHC technologies. This new classification eliminates controversial placement of healing agents (such as fly ash) into either autogenous or autonomous healing. Moreover, the new classification allows easy grouping of new SHC technologies. In this study, we also track the chronological developments of SHC and provides guidance to engineers and contractors when selecting suitable SHC technologies for specific applications, environmental and operational requirements. A systematic analysis was conducted to assess the applicability and technology readiness level (TRL) of various SHC strategies, including alternative binders, minerals, polymers, fungi, bacteria, fibres, shape memory materials, expansive materials, encapsulation, surface spraying, and vascular systems. The findings reveal that while some SHC technologies are approaching practical implementation, others remain at an experimental stage, highlighting the need for more research and development. The insights articulated herein should contribute to the structured advancement of SHC, promoting its transition from laboratory research to real-world implementation. Future advances should focus on robustness, adaptability, and sustainability of SHC applications in infrastructure. • New Classification Proposed: Grouping self-healing concrete (SHC) technologies into “substance filling” and “mechanical closing” instead of “autogenous/autonomous”. • Historical Development Reviewed: Traced the evolution of SHC technologies since 1836. • Technology Readiness Level (TRL) Assessed: for various SHC technologies. • Suitable Applications Summarized: The performance of different SHC technologies under varying pH, temperature, and water environments. • Future Directions Highlighted: Emphasized the need for SHC technologies to improve robustness, adaptability, and sustainability.