A silica sol coating for corrosion protection of reinforce bars in concrete structures was prepared via mechanical blending and ultrasonic dispersion with water glass as the film precursor and cal-cium aluminate as filler.Then the effect of different amounts of calcium aluminate addition on the protec-tive performance of the coating was studied.The structural morphology and ion exchange ability of calci-um aluminate and its hydrates,as well as the structural morphology and protective performance of the coating were characterized by XRD,FT-IR,SEM,ion chromatograph analysis and electrochemical mea-surement.The results indicate that calcium aluminate can be hydrated to form LDH during the coating preparation,thus due to their anion exchange function,LDHs can absorb corrosive chloride ions from cor-rosive media,meanwhile,the layered structure of LDHs may be benefit to alleviate the internal stress generated during the coating curing process,in turn,eliminate the cracking in the coating and improve ef-fectively the barrier performance of the coating,while slow down the infiltration rate of chloride ions and other corrosive ions reaching the surface of the steel bar,eventually enhance the protective performance of the silica sol coating against the steel bar corrosion.
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