Hydration behavior and corrosion protection of cementitious materials incorporating microcapsule hybridized by LDH–NO2

MgAl LDH–NO2 (LDH–NO2) hybrid self-repairing microcapsules were synthesized, and the physical and chemical properties such as microscopic morphology and core ratio of microcapsules were characterized. The effects of microcapsule mixing on the setting time, compressive strength and self-repairing performance of cementitious materials were characterized, and the corrosion protection performance of microcapsules mixed in cementitious materials was revealed. The findings demonstrated that the microcapsules exhibited excellent dispersing properties, and the setting time of the composite cement slurry was prolonged to some extent by the mixed microcapsules. The self-repairing performance of the cementitious material was enhanced by the mixed microcapsules. In comparison to the control specimen, the chloride saturated uptake capacity of the samples mixed with 3 wt% and 6 wt% hybrid microcapsules was improved by 25.94% and 45.57%, respectively. The corrosion inhibition efficiency (η) of self-repairing microcapsules is between 82.28 and 91.04%, and the η of hybrid microcapsules is between 97.47 and 99.04%. The micro-scratches of the coating were effectively repaired by the hybrid microcapsules, the corrosive ion Cl− within the matrix is absorbed and $${\text{NO}}_{2}^{{-}}$$ is released. The corrosion protection of steel bar was significantly improved by the cooperative function of microcapsules and LDH–NO2.