A State-of-the-Art Review of Polymer-Enabled Bionic Vascular Self-Healing Cementitious Materials: Vascular Fabrication, Healing Agent Use, and Healing Efficiency Evaluation

This review provides an overview of the latest advances in bionic vascular self-healing cement, focusing on vascular design, fabrication, selection of healing agents, transport and curing mechanisms, and performance evaluation methods. Compared to systems based on microcapsules and microorganisms, vascular networks enable directed and efficient transport of healing agents and repeated healing; however, the presence of hollow channels results in an inevitable loss of mechanical properties. Additive manufacturing, in situ printing based on Pickering emulsions, and direct printing of cement-based or multi-material systems have enhanced geometric flexibility and scalability. However, issues such as channel quality, polymer-cement interface stability, and on-site quality control remain unclear. Regarding the selection of healing agents, epoxy resin systems are generally more suitable for structural healing, polyurethanes are suitable for rapid sealing and wide or irregular cracks, while silicate healing agents are suitable for healing where cement compatibility and durability are prioritized. The most critical research gap lies in the lack of standardized, full-scale, multi-cycle, and long-term environmental validation, which limits the practical engineering application of vascular self-healing technology. Future research should prioritize the integrated design of various performance metrics, the long-term durability of polymers, standardized benchmark testing, and validation based on actual service conditions.