| Fair-faced concrete is widely used in road,bridge and subway engineering.However,with the decrease of high-quality raw materials such as clean,tidy and sundry sand and stone year by year,the preparation process of fair-faced concrete becomes more complicated,the manufacturing cost increases significantly,and the apparent quality is difficult to reach the ideal state.Therefore,the study of a green waterborne imitation fair-faced concrete curing protective coating may be an effective way to simplify the construction process of fair-faced concrete,solve the problem of poor apparent quality and reduce the manufacturing cost.Based on the above understanding,this paper studies and prepares a kind of imitation fair-faced concrete curing and protective agent.The main contents and conclusions are as follows:（1）The effects of polyol type,silicone oil content,mineral oil/silicone oil ratio and chemical additives on the preparation of curing and protective agent emulsion and its film properties are analyzed.The effects of emulsion particle size,viscosity,surface tension,contact angle,film water absorption rate and water retention rate,compressive strength and water absorption rate of concrete are compared and analyzed.The average particle size of the emulsion is 170.7 nm,the viscosity is 5.2 m Pa·s,and the surface tension is 17.6 m N/m.The water absorption of the coating is 13.2%,and the contact angle is 117.90°.When the mineral oil/silicone oil ratio is 8/6,the water retention rate is 89.7%,the 28 d compressive strength is 94.9%of the blank specimen,and the water absorption rate is 21.8%of the blank specimen.（2）The water retention rate and compressive strength of concrete specimens coated with self-made and commercially available coatings are compared and analyzed.The results show that the water retention rate of the self-made coating is 91.7%,and the 28 d compressive strength of the self-made coating specimen is 95.3%of the blank specimen.The curing effect is significantly better than the commercially available coating;XRD test results show that the amount of CH generated by the self-made coating specimen is similar to that of the specimen under standard curing conditions.The SEM-EDS test results show that the concrete structure coated with the self-made coating is dense,the hydrated C-S-H and CH are interconnected,and the ettringite crystal grows fully;（3）The effect of protective coating on the protective performance of concrete is studied.The water absorption,chloride ion permeability,sulfate corrosion resistance and salt freezing resistance of self-made and commercially available coated concrete specimens are compared and analyzed.The results show that the water absorption of self-made coated specimens is 16.9%of that of blank specimens,and the reduction rate of chloride ion absorption is 75.5%.The water-cement ratio of the specimens coated with the self-made coating is larger and the porosity is higher.After soaking in 5wt%H2SO4 solution for 84 d,the mass of the specimens increased by 0.17%,and the compressive and flexural strength increased by 2.4%and 3.1%.The mass loss of the concrete specimen coated with the self-made coating is 1.19%after 100 cycles of salt freezing in 3.5 wt%Na Cl solution,and the elastic modulus is 89.7%of the initial value.It shows that the self-made imitation water coating has excellent protective effect and is significantly better than the commercially available coating.（4）The effects of nano-materials on the properties of the coating are studied.The properties of the coating,such as chemical resistance,artificial accelerated aging and contact angle,are compared and analyzed.The results show that the coating with nano-materials do not appear any foaming and cracking phenomenon after soaking in 5wt%H2SO4,5wt%Na OH and 3.5wt%Na Cl for 28 d.No yellowing and powdering occurred after exposure to ultraviolet lamp for 792 h.The contact angle of the coating is 141.99°,and the hydrophobic effect is excellent.（5）The construction method of concrete curing and protective agent is studied.The construction steps and construction conditions are preliminarily determined,and the construction effect is demonstrated. |
PDF Full Text Request