The corrosion of embedded rebar in self-healing concrete is seldom reported on and deserves more intensive attention. This study focuses on utilizing biomimetic-induced hydroxyapatite as a means of achieving autonomous self-healing to target issues associated with rebar corrosion in concrete structures. A comprehensive evaluation of the synthesized supramolecular hydrogel as self-healing agent carrier, the simulated self-healing products, and the reinforcement corrosion behaviour in the upscaled self-healing concrete beams was conducted. Results show that the synthesized 2,6-bis [N-(carboxyethyl carbonyl)amino] pyridine (DAP) hydrogel qualifies as a healing agent carrier with high loading capacity and intelligent response after cracking. The feasibility of hydroxyapatite formation via a combination of phosphate ions released by the supramolecular hydrogel and the available calcium ions leached by the cement matrix has been substantiated. The addition of phosphate as the healing agent is effective in mitigating the corrosion of rebar in the designed self-healing concrete beam. It can be explained by the synergistic effect of surface adsorption of chloride ions by the formed hydroxyapatite and the corrosion inhibitor role of the released phosphate.
The application of corrosion inhibitors is a widely adopted strategy for protecting reinforcing steel against electrochemical degradation. However, conventional direct-addition approaches often lead to premature inhibitor depletion and lack controlled-release functionality. In this study, a novel sustained-release capsule-type inhibitor was developed to combat chloride-induced steel corrosion. Ethyl cellulose with high alkali resistance, controllable release and good mechanical properties was used as the shell material and D -sodium gluconate as the core, using a phase separation method and the preparation of the capsule was verified by TG, FT-IR and SEM. The experiment showed that the resulting capsules displayed a "pea-pod" shape (about 0.5–1.0 μm in length and 0.2 μm in diameter) with a compact core/shell structure and when the core/shell ratio was 1:5, the maximum encapsulation efficiency of the capsules was 73.3 %. When dispersed in simulated concrete pore solution, the capsules enabled sustained release of D -sodium gluconate over multiple days. EIS and LPR were used for electrochemical test. And the electrochemical analysis confirmed that the capsule-based inhibitor effectively suppressed corrosion and improved corrosion resistance. Specifically, a dosage of 0.05 % resulted in an inhibition efficiency of 90.7 ± 1.2 % after 7 days. The core-to-shell ratio was identified as a critical factor governing both the release kinetics and the overall protective performance, with the 1:5 formulation demonstrating optimal corrosion inhibition. This study offers a promising strategy for the design and application of intelligent corrosion inhibitors in reinforced concrete structures.
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