A review of novel self-healing concrete technologies

Cracks and damage of concrete during service pose threats to its safety and durability. Compared to traditional repair techniques, self-healing strategy for concrete repair is regarded as a promising technology. This paper reviews the recent advancement in concrete self-healing. It primarily outlines various mechanisms and required repair materials for concrete self-healing. Two selfhealing techniques, namely microcapsule self-healing and microbial self-healing, are highlighted. Internal and external factors influencing the effectiveness of concrete self-healing, characterization methods for self-healing effectiveness, and engineering applications are summarized and discussed in this paper. The combination of multiple self-healing techniques can yield excellent selfhealing effect compared with the single technique. The maximum crack healing width by the microorganisms and microcapsules was 970 mu m. However, most of the current self-healing research remains at the laboratory stage, the composite self-healing techniques should consider practical conditions and cost factors, and their self-healing mechansims should also be investigated detailedly. Standardization and regulation of self-healing test methods are necessary to facilitate the development of new self-healing concrete materials and technologies.