Preparation And Performance Of Nano-modified Fluorine-containing Concrete Anticorrosive Coating

The existing concrete structure of urban interchange will be affected by a variety of corrosion factors during service,which will lead to the performance decline,especially the chloride ion in the salt during snow melting,which will cause local damage on the concrete surface and cause potential harm to the bridge and cannot work for a long time.Therefore,according to the environmental corrosion characteristics of existing concrete in snow melting salt environment,a series of nano-material modified water-based fluorine-containing acrylate coatings with excellent performance are developed,which have important engineering practical value for improving the protection performance of concrete in the snow melting salt environment.In this paper,nano-TiO₂ and nano-SiO₂ modified fluorinated acrylate coatings obtained by different treatment methods were used to study the conventional properties of the composite coating and its influence on the freeze-thaw corrosion resistance of concrete.The effects of coupling agent type,dosage and treatment on water absorption and hydrophobic properties of spherical nano-TiO₂,rod-like nano-TiO₂,nano-SiO₂ sol and nano-SiO₂ microsphere modified composite coating were studied.The mechanical properties,chemical corrosion resistance,aging resistance and chloride ion penetration resistance of the composite coating were investigated after the introduction of nano-particles.The corrosion resistance of concrete coated with composite coating was evaluated,and the protective effect of coating on concrete was evaluated comprehensively.The main conclusions are as follows:(1)When the fluorine-containing acrylate emulsion is modified with FAS-treated nano-TiO₂(with the content of 3%),the water resistance and hydrophobic properties of the composite coating are the best.The contact angle of the composite coating to water is 115.44°,the water absorption is 0.72%,the adhesion is 1.66 MPa,the pencil hardness is 5H,the maximum impact strength is 50cm,and the acid,alkali and salt corrosion resistance rates are20%,16%and 13%respectively,the chloride ion penetration is 6.37×10^-2mg·(cm²·d)^-1,the color difference of aging resistance is 0.78,and the gloss is 7.2.(2)When KH560 modified nano SiO₂ sol is introduced into the coating,the hardness and corrosion resistance of the composite coating are better.When the fluorine-containing acrylat emulsion is modified with 20%modified nano-SiO₂ sol,the adhesion of the composite coating is 1.92 MPa,the pencil hardness is 5H,the impact strength is higher than 50cm,and the acid,alkali and salt corrosion resistance rate is respectively 16%,11%,10%,the contact angle to water is 103.57°,the water absorption rate is 0.75%,the chloride ion penetration resistance is 6.99×10^-2mg·(cm²·d)^-1,the aging resistance color difference is 0.5,the gloss is 7.2.(3)By comparing the hardness,brightness,color difference,carbonization depth and compressive strength of concrete coated with several nano-composite coatings before and after freezing and thawing corrosion resistance of snowmelt salt,the results show that after the salt freezing cycle test for 40 times,the performance loss of FAS treated nano TiO₂ protective coating layer is the least.After the putty pretreatment on the surface of concrete,the concrete composite coating has good resistance to freezing and thawing corrosion of snowmelt salt.