Study On The Protective Effect Of Modified Nano-film-forming And Penetrating Composite Coating Concrete

Concrete structures often suffer from complex and erosive environmental effects during actual use,which will cause the decline in the use function and bearing capacity of the concrete structure engineering,affect the safe use of the structure,reduce the durability of the concrete structure,and reduce its service life.Surface coating treatment is an effective method to improve the resistance of concrete to the external aggressive environment.Research on the direction of surface coating treatment has important practical significance for the protection of concrete structures.In this paper,three organic film-forming coatings of acrylic resin,chlorinated rubber,and alkyd resin are selected.Modified nano-film-forming coatings are prepared by nano-SiO2 and organic film-forming coatings.Based on this,permeable silane paste Coating,constructing a modified nano-film-forming and permeable composite coating system.The composite coating system concrete is taken as the research object,and the coating concrete is subjected to experimental research on water absorption performance,resistance to chloride salt erosion,and resistance to carbonization.The main results are as follows:（1）The combination of physical and chemical methods is used to modify the surface hydrophobicity of nano-SiO2,so that chemical bonding occurs between nano-SiO2 and the silane coupling agent,hydrophobic alkyl groups are coated on the surface of nano-SiO2,and nano-SiO₂ was modified to hydrophobic nano-SiO₂.（2）Using the ultrasonic dispersion method,adding nano-SiO2 to the film-forming coating can increase the surface contact angle of the coating concrete,effectively enhancing the hydrophobic performance of the film-forming coating,and compared with non-hydrophobic modified nano-SiO₂ particles,hydrophobic modified nano-SiO₂ has a better effect on improving the surface contact angle of film-coated concrete.With the increase of the nano-SiO2 content,the surface contact angle tends to increase and then decrease,and agglomeration will occur.However,hydrophobically modified nano-SiO2 will delay the occurrence of agglomeration.In addition,the best amount of nano-SiO₂ in different types of film-forming coatings is determined by the measurement of the surface contact angle.（3）Through water absorption test research,it was found that under the same coating system thickness,the water absorption of the concrete test block decreased to a certain extent after the film coating was applied,and as the thickness of the coating system gradually increased,the concrete test block The water absorption of water decreases gradually,and there is an exponential negative correlation between the water absorption of concrete and the thickness of the coating;After adding an appropriate amount of hydrophobically modified nano-SiO2 and non-hydrophobically modified nano-SiO2 to the film-forming coating,the hydrophobically modified nano-SiO₂ film-forming coating corresponds to a larger decrease in the water absorption rate of the concrete test block;based on the modified nano-film-forming coating,combined with the permeable silane paste coating,a composite coating system is formed,which is compared with the modified nano-film Film-forming coating,composite coating system concrete water absorption performance decreased more significantly.（4）Through the chloride salt erosion test and accelerated carbonization test research,it is found that after the surface coating treatment on the concrete surface,the surface coating treatment has a certain degree of resistance to chlorine salt erosion resistance and carbonization resistance,and the chlorine salt erosion resistance and carbonization resistance The magnitude of performance improvement is as follows:composite coating system>hydrophobic modified nano-film-forming coating>non-hydrophobic modified nano-film-forming coating>film-forming coating.（5）The correlation between chloride ion diffusion coefficient and chloride salt erosion time was determined by least squares method,and fitting equations of chloride ion diffusion coefficients of different types of coated concrete with time were obtained.Based on Fick’s second factor,a time factor was established.Prediction model of coated concrete under the environment of chloride salt erosion based on the law.In addition,based on the random forest,support vector machine and BP neural network intelligent algorithm,a prediction model for chloride resistance of coated concrete is established to analyze the prediction results of different types of coated concrete.It is found that the prediction model based on the random forest algorithm has the best effect,and can be applied to the prediction of the resistance of coated concrete to chloride salt erosion.