Ca-Al LDH hybrid self-healing microcapsules for corrosion protection

• The self-healing microcapsules were hybridized by Ca-Al LDH in the form of surface loading. • The self-healing and chlorine adsorption properties of hybrid microcapsules were investigated. • The corrosion resistance mechanism of microcapsules was characterized by EIS. • First-principles based on density functional theory was applied to study the hybrid mechanism. Ca-Al LDH hybrid self-healing microcapsules were fabricated with tung oil as core and ethyl cellulose (EC) as wall via solvent evaporation method. The self-healing and chlorine adsorption properties of hybrid microcapsules in cement-based materials were investigated. The corrosion resistance performance of microcapsules in simulated chlorine-contaminated concrete pore solution (SCPS) was characterized by electrochemical probe technique. First-principles based on density functional theory was applied to study the hybrid mechanism of Ca-Al LDH on self-healing microcapsules. The results demonstrate that the nano-layered Ca-Al LDH within the hybrid wall provided additional nucleation sites for cement hydration. The chlorine adsorption capacity of cement paste doped with 3 wt % and 6 wt % microcapsules was 14.7% and 26.7% higher than that of pure cement paste in SCPS, respectively. Hybrid microcapsules improved the anticorrosion of steel bars in SCPS by coupling effect of self-healing and chlorine resistance. The formation of Ca-Al LDH@EC hybrid materials is an exothermic process with perfect binding stability. The chlorine adsorption property of microcapsules was improved by the interface charge redistribution of Ca-Al LDH@EC hybrid materials.