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This post was last edited by Wang Wei2 on 2020-6-3 at 10:12. Case study on corrosion prevention in industrial concrete structures – Application of resin-modified rubber polymer coatings in concrete tanks. As we know, epoxy-based coatings are used in petrochemical concrete sewage tanks; from a molecular structure perspective, they have poor resistance to aging and a short service life. Although the use of chlorosulfonated polyethylene coatings solves some problems related to aging resistance, issues concerning the strength, adhesion, and swelling in water of the coatings have not been adequately addressed. Especially open concrete pools. Therefore, the first issue to address is how to choose a coating that possesses the properties of epoxy coatings while also having good aging resistance. 1. Rationale for choosing a resin-modified rubber polymer coating: Using the \"resin-modified rubber high-weatherability composite coating\" (hereinafter referred to as high-weatherability composite coating) in combination with epoxy resin is an excellent approach. This is because the strength, hardness, adhesion, gloss retention, aging resistance, and corrosion resistance of polymer coatings are superior to those of ordinary chlorosulfonated polyethylene coatings. It is mainly formulated from organic substances, polyamidoaliphatic oleic acid adducts, chlorosulfonated polyethylene resin, and high-quality coating additives. The reason is as follows: high-weatherability composite coatings are mainly made by adding a certain amount of epoxy resin to chlorosulfonated polyethylene resin. That is: based on an adhesive, a rubber with active functional groups is first synthesized. In this way, under the action of these two film-forming substances, the properties of the resulting coating change significantly. The crosslinking mechanism of epoxy resin as a crosslinking agent for chlorosulfonated polyethylene is as follows: The macromolecules of epoxy resin have an epoxy group at each end, and these groups can undergo intramolecular crosslinking with the chlorosulfonyl groups on the macromolecules of chlorosulfonated polyethylene, thereby enabling the polymer to form a three-dimensional structure. In this way, a composite curing agent and various functional additives are added at room temperature and applied to the surface of an object, where a chemical reaction takes place to cure a networked polymer structural material. This material contains both resin chains and rubber segments in its structure; the cured paint film falls between resinous and rubbery materials. The strength and adhesion of this material are much higher than those of chlorosulfonated polyethylene coatings. Coatings resulting from the addition reaction of epoxy resin, chlorosulfonated polyethylene resin, and other materials exhibit significant advantages over coatings using other crosslinking systems in terms of water resistance, heat resistance, chemical resistance, stability when stored as a single-component product, crosslinking speed, color stability, coloring ability, resistance to contamination, transparency of the varnish film formed, and ease of dispersion during coating production. It is the chlorosulfonated polyethylene coating, which is recognized abroad as having the highest total score among the ten major technologies (2). Its excellent performance has been clearly demonstrated through practical applications and production. Because this material can, by changing other components such as epoxy resin, yield different types of highly weather-resistant composite coatings. 2. Basis for formulating the construction plan: Based on the usage conditions of the existing sewage tank, the first issue to address is the adhesion between the primer and the concrete ； Anti-aging and anti-permeation properties of epoxy-based fiberglass reinforced plastics ； Swelling of the surface layer and its issues regarding water resistance and corrosion resistance. Therefore, considering the inherent properties of the polymer composite coating, the following application procedure is adopted: one coat of primer – fiberglass with three layers of cloth – two coats of intermediate paint – one coat of sealing paint. The main basis for the design is as follows: 2.1 A primer – The primer uses E44 epoxy resin; due to the presence of ether groups, hydroxyl groups, and highly reactive epoxy groups in its structure, this resin possesses very strong adhesion properties. Taking advantage of the properties of this resin, coupled with the relatively rough surface of cement, facilitates the adhesion and penetration of the paint film. This helps the coating penetrate into the concrete, serving an anchoring function. A resin layer of a certain thickness is formed, thereby creating an anti-corrosion base layer with high strength. 2.2 Three-layer fabric-based fiberglass. The glass fabric used is “three-free” type (wax-free, alkali-free, and untwisted), with a thickness of 0.2 mm and a weave density of 12×12 threads per centimeter. The anti-corrosion material employed is a highly weather-resistant composite coating. The resulting fiberglass possesses both the strength of resin-based fiberglass and a certain degree of toughness. 2.3 Second coat of intermediate paint: A high-weatherability composite glass flake coating in a different color is used for each coat; to enhance the coating’s impermeability, the original coating was modified by adding a certain amount of glass flakes. It is mainly to improve the impermeability and crack resistance of the coating. 2.4 One coat of topcoat: Apply one coat of a highly weather-resistant composite coating on its surface, ensuring that its color is distinct from that of the intermediate coat. The main purpose is that after applying the two coats of flake-free paint, the surface remains relatively rough; by then using a flake-free paint for sealing, the surface finish can be improved. In short, in terms of the selection of materials for coating design, it follows the principle of meeting the required usage conditions; from the base layer to the top layer, this involves using pure resin as a base coat followed by high-weatherability composite coatings. In other words, it combines the melting type and swelling type of coatings in an organic way. Eliminate the interface that previously existed between the melt-type and the swelled-type. 3. Application: The inner wall of a concrete sedimentation tank in the refinery’s wastewater treatment system was constructed using the aforementioned materials and methods. After nearly 5 years of use, inspections showed that the paint coating remained in good condition, with no peeling, flaking, or cracking. There was no change when comparing the results of the scratch test with the post-completion quality. The surface after impregnation performs much better than when a glass fiber reinforced plastic composite layer was created using chlorosulfonation and epoxy; there is absolutely no occurrence of delamination or bulging on the surface of the anti-corrosion layer. 4. Conclusion After nearly 5 years of use, it exhibits the following main characteristics: 4.1 Excellent water and corrosion resistance. It has a low surface porosity, which gives it excellent impermeability in sewage or humid conditions; it is resistant to cracking, wear-resistant, and has good strength. 4.2 The high-weather-resistant composite coating film is tough; its hardness, aging resistance, cold resistance, gloss, and vivid color are all superior to those of chlorosulfonated polyethylene coatings. 4.3 The highly weather-resistant composite coating offers significantly improved corrosion resistance compared to chlorosulfonated coatings, resolving the swelling problem of chlorosulfonated polyethylene coatings in water systems. Especially in terms of gloss retention, chlorosulfonated polyethylene coatings become powdered and turn white after being used for a while. This material has seen significant improvements in this regard; the decorative quality of its surface coating has been greatly enhanced, making it comparable to organic fluorine coatings. Therefore, taking into account the operating conditions of sewage tanks, a coating that combines melting-type and swelling-type organic components was selected, which solved the issue related to the combined service life of these two types and increased the service life of the coating.