Method for repairing a steel sheet locally severely corroded

Abstract

This application relates to the field of steel structure maintenance and protection technology, specifically disclosing a method for repairing locally severely corroded steel plates. The method involves: cleaning the surface rust of the steel plate and delineating the area to be repaired; applying a water-based EAU zinc-rich primer to the area to be repaired to form a zinc-rich primer layer; impregnating a non-woven fabric with a water-based EAU high-barrier intermediate coat to form a non-woven fabric-reinforced high-barrier layer; laying a fiberglass geogrid, followed by pouring a water-based EAU high-barrier intermediate coat to form a fiber geogrid-reinforced load-bearing layer; and finally applying a water-based EAU wear-resistant and anti-corrosion topcoat to the surface of the fiber geogrid-reinforced load-bearing layer to form a wear-resistant and anti-corrosion topcoat, thus forming a multi-layer repair system, completing the repair. This repair method can be used to repair locally severely corroded steel plates, and the repair process is safe and risk-free. The repaired steel plate has good load-bearing capacity and corrosion resistance, and can work safely and reliably.

Description

Technical Field

[0001] This application relates to the field of steel structure maintenance and protection technology, and more specifically, it relates to a method for repairing locally severely corroded steel plates. Background Technology

[0002] Steel structure platforms are frequently used as working surfaces in industries such as chemical, petroleum, and ports. However, steel structure systems are susceptible to corrosion in high humidity and corrosive environments, leading to reduced safety, usability, and durability. Due to the accumulation of corrosive media or defects in the anti-corrosion coating, steel plates in steel structure platforms or staircases often experience severe localized damage. The presence of localized corrosion significantly reduces the load-bearing capacity and ductility of the steel plates in actual engineering projects, causing the overall performance of the steel structure system to continuously deteriorate and seriously threatening the safe operation of steel structure facilities. Therefore, the repair of locally corroded steel plates becomes particularly important. The repair process of steel structure plates should be free of safety risks, and the repaired steel plates should have good load-bearing capacity and corrosion resistance, enabling safe and reliable operation.

[0003] Existing methods for repairing locally corroded steel structures include grouting reinforcement, welding ribs or attaching steel plates, grouting clamp reinforcement, internal concrete filling reinforcement, fiber optic (FRP) interlayer grouting reinforcement, carbon fiber (CFRP) reinforcement, and laser cladding technology.

[0004] Regarding the aforementioned technologies, the inventors discovered that, for the repair of steel plate structures in flooring, grouting and grouting clamp reinforcement methods are not suitable due to the high fluidity of the grout; welding ribs or attaching steel plates cannot solve the problem of steel plate corrosion, and there are safety risks during the welding process, which can easily cause new damage to the steel plate; the internal concrete reinforcement method significantly increases the thickness of the steel plate, and when the concrete is too thin, its tensile and flexural strengths do not meet the requirements, making it unsuitable for repairing steel plates; fiber sandwich grouting, carbon fiber reinforcement, and laser cladding technology are all relatively expensive and complex in process, making them unsuitable for large-scale application. Summary of the Invention

[0005] To improve the repair effect on steel plates with severe localized rust and damage, this application provides a repair method for steel plates with severe localized rust.

[0006] Firstly, this application provides a method for repairing locally severely rusted steel plates, employing the following technical solution: A method for repairing locally severely rusted steel plates includes the following steps:

[0007] S1. Clean the surface rust of the steel plate and delineate the area to be repaired by extending the edge of the damaged part outwards.

[0008] S2. Apply water-based EAU zinc-rich primer to the area to be repaired, and allow it to dry and cure to form a zinc-rich primer layer;

[0009] S3. A non-woven fabric is used to impregnate the water-based EAU high-barrier intermediate coating, which is then adhered to the surface of the zinc-rich primer layer. After drying and curing, a non-woven fabric-reinforced high-barrier layer is formed.

[0010] S4. Lay fiberglass geogrid, surround the damaged area, then pour water-based EAU high-barrier intermediate coating, and after drying and curing, form a fiber geogrid reinforced load-bearing layer.

[0011] S5. Finally, apply water-based EAU wear-resistant and anti-corrosion topcoat to the surface of the fiber grid reinforced load-bearing layer. After drying and curing, a wear-resistant and anti-corrosion topcoat is formed, creating a multi-layer repair system, thus completing the repair.

[0012] By adopting the above technical solution, a multi-layer repair system is formed from bottom to top on the surface of locally severely rusted steel plates. This system consists of a zinc-rich primer layer, a non-woven fabric reinforced high-barrier layer, a fiber grid reinforced load-bearing layer, and a wear-resistant and anti-corrosion cover layer. Through the layered repair method, the corrosion resistance and load-bearing capacity of the locally rusted steel plates are significantly improved. The top layer, which forms a wear-resistant and anti-corrosion cover layer, enhances the durability and wear resistance of the repaired parts of the steel plate.

[0013] Water-based EAU materials are used to make coatings that use water as a solvent and do not contain heavy metal ions or other harmful substances. Their low volatile organic compound (VOC) content makes the application process more environmentally friendly, and the use of water as a solvent also reduces safety risks during the application process.

[0014] Nonwoven fabric, as a reinforcing material, significantly enhances the structural strength of the water-based EAU high-barrier intermediate coating, resulting in a nonwoven-reinforced high-barrier layer with excellent load-bearing capacity, greater durability, and stability. Simultaneously, the nonwoven fabric reinforcement further improves the barrier properties of the water-based EAU high-barrier intermediate coating, effectively preventing moisture and corrosive media from penetrating the coating and providing excellent protection for the substrate structure, thereby protecting the steel plate from further corrosion.

[0015] Fiberglass geogrids possess high strength and durability, significantly improving the tensile and tear strength of water-based EAU high-barrier intermediate coatings. Furthermore, the three-dimensional structure of the fiberglass geogrid provides better support and fixation, resulting in a stronger bond between the intermediate coating and the substrate structure. This effectively enhances the overall load-bearing capacity of the steel plate, reducing the risk of further deformation or breakage.

[0016] When micro-cracks appear in a multi-layered repair system, both non-woven fabrics and fiberglass geogrids can bridge these cracks, preventing them from propagating into larger damage.

[0017] Optionally, in step S2, before applying water-based EAU zinc-rich primer to the area to be repaired, the following pretreatment is performed: apply water-based EAU rust-resistant primer to the area to be repaired, and after drying and curing, a rust-resistant primer layer is formed.

[0018] By adopting the above technical solution, the repair method of this application can be applied to rusted surfaces without the need for sandblasting. This is because when the rust-blocking primer prepared from water-based EAU material is applied to the steel plate surface, the active ingredients such as the rust-converting agent inside can penetrate into the rust layer and react chemically with the rust layer on the steel plate surface, converting the iron oxide rust on the steel plate surface into a strong complex, thereby fixing the rust and preventing further rust spread. Compared with traditional sandblasting methods, water-based EAU materials do not generate large amounts of wastewater, waste residue, and dust during construction, which is beneficial to protecting the health of construction workers and the environment.

[0019] When steel plates are rusted and cannot be derusted, the repair method of this application can achieve significant repair effects and establish a solid rust-resistant primer layer for multi-layer repair systems.

[0020] Optionally, the raw materials of the water-based EAU rust primer include a composite emulsion and a curing component, by weight.

[0021] The composite emulsion comprises 90-110 parts by weight of an aqueous EAU composite resin emulsion;

[0022] The curing component comprises 12-16 parts curing agent, 0.1-0.3 parts wetting agent, 0.2-0.5 parts dispersant, 0.2-0.5 parts defoamer, 0.6-1.2 parts film-forming aid, 12.5-17.5 parts aminotrimethylenephosphonic acid, 11-16 parts zinc phosphate, 5-9 parts aluminum tripolyphosphate, and 25-35 parts water.

[0023] By adopting the above technical solution, aminotrimethylenephosphonic acid has good dispersibility and sustained-release properties, can dissolve oxides on metal surfaces, and form strong and stable complexes with various metal ions such as iron, copper, aluminum, and zinc, thereby effectively removing dirt and oxides from metal surfaces and improving the smoothness and corrosion resistance of metal surfaces.

[0024] Zinc phosphate can react with Fe on the metal surface. 3+ It forms a strong complex and deposits on the metal surface to create a dense protective film. This protective film has excellent corrosion inhibition and shielding effects, effectively suppressing the anodic reaction on the metal surface and preventing further oxidation and corrosion of severely rusted steel plates. It can also complex with the hydroxyl and carboxyl functional groups in the rust-resistant primer to form corrosion-inhibiting complexes, enabling a chemical bond between the water-based EAU rust-resistant primer and the steel substrate, thus improving the coating's adhesion and impermeability.

[0025] When zinc phosphate and aminotrimethylene phosphonic acid are combined, the resulting primer is easy to mix evenly and is less prone to defects such as sagging and brush marks during application. Both are non-toxic or low-toxic substances, and the resulting primer meets environmental protection requirements.

[0026] Optionally, the raw materials of the waterborne EAU zinc-rich primer include a composite emulsion, a curing component, and a powder component; by weight, the composite emulsion includes 90-110 parts of waterborne EAU composite resin emulsion.

[0027] The curing component comprises 12-16 parts curing agent, 0.1-0.3 parts wetting agent, 0.3-0.6 parts dispersant, 0.2-0.5 parts defoamer, 0.6-1 part film-forming aid, and 25-35 parts water;

[0028] The powder composition includes 59-67 parts zinc powder and 3-5 parts nano calcium carbonate.

[0029] By adopting the above technical solution, zinc powder, a chemically active pigment, has an electrode potential of -0.7628V, while iron has an electrode potential of -0.409V. Therefore, zinc can act as a sacrificial anode on the steel surface, protecting the steel plate surface and preventing further corrosion of the steel substrate. Simultaneously, the corrosion products of the zinc powder can fill the pores between the primer and the substrate, sealing damaged areas of the steel substrate.

[0030] The zinc powder significantly enhances the adhesion between the zinc-rich primer layer and the steel plate substrate through the protective mechanism of the sacrificial anode and physical bonding, thereby improving the repair effect of the repair method of this application.

[0031] The addition of nano-calcium carbonate can fill the microstructure of the coating, reduce porosity and defects, significantly improve the density of the coating, and enhance the overall performance of the zinc-rich primer layer.

[0032] Optionally, the raw materials of the waterborne EAU high-barrier intermediate coating include a composite emulsion, a curing component, and reinforcing powder; by weight, the composite emulsion includes 80-100 parts of waterborne EAU composite resin emulsion.

[0033] The curing component comprises 11.2-15.7 parts curing agent, 0.1-0.3 parts wetting agent, 0.2-0.5 parts dispersant, 0.2-0.5 parts defoamer, 0.6-1.2 parts film-forming aid, 0.3-0.6 parts anti-settling agent, 0.3-0.6 parts cellulose ether, and 32-38 parts water;

[0034] The reinforcing powder comprises 15.6-22.4 parts slag powder, 3-7 parts steel slag powder, and 1.2-1.9 parts sodium silicate.

[0035] By adopting the above technical solution, an inorganic micro-powder mixture formed from ultrafine slag powder and ultrafine steel slag powder can undergo an active reaction with alkaline sodium silicate to form an alkali-activated gel material. This alkali-activated gel material has a certain strength and can form a good bond with fiber-reinforced grids under the action of composite emulsion, constituting a composite material load-bearing layer. This effectively improves the adhesion between layers of the multi-layer repair system, enabling the load-bearing capacity of the multi-layer repair system to meet the required standards.

[0036] Optionally, the raw materials of the water-based EAU wear-resistant and corrosion-resistant topcoat include composite emulsion, curing components and reinforcing powder;

[0037] The composite emulsion comprises 80-100 parts by weight of an aqueous EAU composite resin emulsion;

[0038] The curing component comprises 11-14 parts curing agent, 0.2-0.4 parts wetting agent, 0.2-0.4 parts dispersant, 0.2-0.5 parts defoamer, 0.5-0.8 parts film-forming aid, 0.2-0.4 parts leveling agent, 5-8 parts water-based colorant, and 25-32 parts water;

[0039] The reinforcing powder comprises 2.5-5.5 parts silicon carbide and 3-7 parts nano-silica.

[0040] By adopting the above technical solutions, both silicon carbide and nano-silica have high hardness and strength. When mixed, they can fully leverage their advantages in wear resistance, enabling the formed wear-resistant and anti-corrosion coating to withstand greater external forces and pressures, and thus exhibiting higher wear resistance.

[0041] Optionally, the curing agent is any one or a combination of two of waterborne polyurea resin or polyisocyanate curing agents.

[0042] Optionally, the area to be repaired is an area extending 10-50cm outwards from the edge of the damaged part.

[0043] Optionally, the thickness of the nonwoven fabric reinforced high-barrier layer is 0.5-1mm, and the thickness of the fiber grid reinforced load-bearing layer is 3-5mm.

[0044] By adopting the above technical solutions, by designing the thickness of the non-woven fabric to strengthen the high-barrier layer, and by designing the thickness of the glass fiber geogrid to adjust the thickness of the fiber geogrid to enhance the load-bearing layer, the load-bearing capacity of the multi-layer repair system can be adjusted.

[0045] In summary, this application has the following beneficial effects:

[0046] 1. The repair method of this application forms a multi-layer repair system around the severely corroded steel plate through a layered repair approach, which significantly improves the corrosion resistance and load-bearing capacity of the corroded steel plate. The outermost wear-resistant and anti-corrosion surface layer enhances the wear resistance and durability of the repaired area of ​​the steel plate, further extending the service life of the repaired steel plate.

[0047] 2. Non-woven fabric reinforced waterborne EAU high-barrier intermediate coating and 3D fabric reinforced waterborne EAU high-barrier intermediate coating effectively enhance the overall load-bearing capacity of the steel plate and reduce the risk of further deformation or damage to the steel plate.

[0048] 3. The zinc phosphate particles in the water-based EAU rust-curing primer are relatively fine. Through reaction with the rust layer and other components in the primer, a dense phosphate protective film is formed on the steel plate surface, which significantly improves the adhesion and smoothness between the primer layer and the steel plate substrate. On the other hand, the zinc powder particles in the water-based EAU zinc-rich primer are relatively large. Through the sacrificial anode protection mechanism, it effectively inhibits and shields severely rusted steel plates. The addition of the rust-curing primer layer makes the advantages of the two primer layers complementary, which significantly improves the repair effect of the repair method of this application when repairing steel plates that are severely rusted to the point that rust removal is not possible.

[0049] 4. The repair method in this application uses coatings made of water-based EAU materials, which can be applied to areas with rust without the need for sandblasting, ensuring safe construction, eliminating fire risks, and meeting the requirements of environmental protection and sustainable development. Detailed Implementation

[0050] The following examples and comparative examples will provide further detailed description of this application.

[0051] raw material

[0052] Unless otherwise specified, all raw materials used in the embodiments and comparative examples in this application are commercially available products, specifically:

[0053] Polytetrahydrofuran ether diol, selected from Deyitai New Materials, DYT-005;

[0054] Toluene diisocyanate, selected from Shanghai Yuanye Biotechnology Co., Ltd., W10121;

[0055] Dibutyltin dilaurate, selected from Shanghai Yuanye Biotechnology Co., Ltd., W10608;

[0056] Hydroxyethyl acrylate, selected from Jingtai Chemical, A264959;

[0057] Benzoyl peroxide, selected from West Asia Chemicals, A65330;

[0058] Tripropylene glycol diacrylate, selected from Yuming Chemical, EM223TF;

[0059] Bisphenol A epoxy resin, selected from Senqiang Environmental Protection Technology, E-44;

[0060] Waterborne polyurea resin curing agent, selected from Jinwanli, J-6736;

[0061] Polyisocyanate curing agent, selected from Shi Quanxing, F-38;

[0062] The wetting agent is selected from Evonik Tega, Twin4100;

[0063] The dispersant was selected from BYK 163;

[0064] Defoamer, selected from BYKA500;

[0065] Film-forming aid, selected from Runtian Chemical, 23812;

[0066] Anti-settling agent, selected from Zhonglianbang, K-288;

[0067] Cellulose ether, specifically carboxymethyl cellulose, selected from Jianyang Xinghua, XH-666;

[0068] Leveling agent, selected from BYK 333;

[0069] Water-based colorant, selected from AStrong, WVW107;

[0070] Aminotrimethylenephosphonic acid, choose Zihaoyao New Materials, HY565;

[0071] Zinc phosphate, selected from LEROAN, LH-LSX, with a particle size of 800 mesh;

[0072] Zinc powder, purity ≥ 99.5%, particle size 200 mesh;

[0073] Nano-sized silica with an average particle size of 20 nm;

[0074] Fiberglass geogrid, sourced from Shandong Lianxiang Engineering Materials Co., Ltd.

[0075] Nano-calcium carbonate, a modified calcium carbonate, is selected from Hangzhou Jikang New Materials Co., Ltd., SS-CAC50;

[0076] Slag powder, specific surface area ≥600m² 2 / Kg;

[0077] Steel slag powder, specific surface area ≥600m² 2 / Kg.

[0078] Preparation of waterborne EAU composite resin emulsion

[0079] The waterborne EAU composite resin emulsion, selected from Suzhou Dacheng Environmental New Materials Co., Ltd., comprises 40g polytetrahydrofuran ether diol, 10g toluene diisocyanate, 0.5g dibutyltin dilaurate, 8g dimethyl carbonate, 22.6g hydroxyethyl acrylate, 7g benzoyl peroxide, 14g tripropylene glycol diacrylate, and 45g bisphenol A epoxy resin. The preparation method of the above waterborne EAU composite resin emulsion includes the following steps:

[0080] In a nitrogen atmosphere, polytetrahydrofuran ether diol and toluene diisocyanate were added to a reaction vessel, heated and stirred at 80°C, then dibutyltin dilaurate and dimethyl carbonate were added, and the reaction was continued to be stirred for 3.5 h. After that, hydroxyethyl acrylate was added to end cap and then poured into 150 mL of deionized water and stirred to obtain a polyurethane acrylate emulsion.

[0081] Bisphenol A epoxy resin and polyurethane acrylate emulsion were mixed and stirred, then benzoyl peroxide and tripropylene glycol diacrylate were added. The mixture was stirred at 150°C and 350 r / min for 2.5 h, then cooled and discharged to obtain the final product.

[0082] Preparation examples of water-based EAU rust-curing primer: 1.1-1.3

[0083] Preparation Example 1.1

[0084] The raw materials and dosages of the water-based EAU rust primer are shown in Table 1. The curing agent is a water-based polyurea resin and a polyisocyanate curing agent with a mass ratio of 1:1, and the water is deionized water.

[0085] Table 1

[0086]

[0087]

[0088] The preparation method of the above-mentioned water-based EAU rust-curing primer includes the following steps:

[0089] S1. Mix the curing agent, wetting agent, dispersant, defoamer, film-forming aid, aminotrimethylenephosphonic acid, zinc phosphate, aluminum tripolyphosphate and water, and stir evenly to form a curing component;

[0090] S2. Mix the water-based EAU composite resin emulsion and the curing component evenly to obtain the final product.

[0091] Preparation Examples 1.2-1.3

[0092] The water-based EAU rust-curing primer differs from Preparation Example 1.1 in that the raw materials and amounts are shown in Table 1, while the other steps are the same as in Preparation Example 1.1.

[0093] Examples of preparation of waterborne EAU zinc-rich primer 2.1-2.3

[0094] Preparation Example 2.1

[0095] The raw materials and dosages of the waterborne EAU zinc-rich primer are shown in Table 2. The curing agent is a waterborne polyurea resin and a polyisocyanate curing agent with a mass ratio of 1:1, and the water is deionized water.

[0096] Table 2

[0097]

[0098] The preparation method of the above-mentioned water-based EAU zinc-rich primer includes the following steps:

[0099] S1. Mix the curing agent, wetting agent, dispersant, defoamer, film-forming aid and water evenly to form a curing component;

[0100] S2. Mix zinc powder and nano-calcium carbonate to form a powder;

[0101] S3. Mix the water-based EAU composite resin emulsion, curing component and powder evenly to obtain the final product.

[0102] Preparation Examples 2.2-2.3

[0103] The water-based EAU zinc-rich primer differs from the preparation example 2.1 in that the raw materials and amounts are shown in Table 2, while the other steps are the same as in the preparation example 2.1.

[0104] Preparation examples of waterborne EAU high-barrier intermediate coatings: 3.1-3.3

[0105] Preparation Example 3.1

[0106] The raw materials and dosages of the water-based EAU high-barrier intermediate coating are shown in Table 3. The curing agent is a polyisocyanate curing agent, and the water is deionized water.

[0107] Table 3

[0108]

[0109] The preparation method of the above-mentioned water-based EAU high-barrier intermediate coating includes the following steps:

[0110] S1. Mix the curing agent, wetting agent, dispersant, defoamer, film-forming aid, anti-settling agent, cellulose ether and water evenly to form a curing component;

[0111] S2. Mix slag powder, steel slag powder and sodium silicate to form a reinforcing powder;

[0112] S3. Mix the water-based EAU composite resin emulsion, curing component and reinforcing powder evenly to obtain the final product.

[0113] Preparation Examples 3.2-3.3

[0114] The water-based EAU high-barrier intermediate coating differs from that of Preparation Example 3.1 in that the raw materials and amounts are shown in Table 3, while the other steps are the same as those in Preparation Example 3.1.

[0115] Examples of preparation of water-based EAU abrasion-resistant and corrosion-resistant topcoat: 4.1-4.3

[0116] Preparation Example 4.1

[0117] The raw materials and dosages of the water-based EAU wear-resistant and anti-corrosion topcoat are shown in Table 4. The curing agent is water-based polyurea resin, and the water is deionized water.

[0118] Table 4

[0119]

[0120] The preparation method of the above-mentioned water-based EAU wear-resistant and anti-corrosion topcoat includes the following steps:

[0121] S1. Mix the curing agent, wetting agent, dispersant, defoamer, film-forming aid, leveling agent, water-based color paste and water evenly to form a curing component;

[0122] S2. Silicon carbide and nano-silica are mixed to form a reinforcing powder;

[0123] S3. Mix the water-based EAU composite resin emulsion, curing component and reinforcing powder evenly to obtain the final product.

[0124] Preparation Examples 4.2-4.3

[0125] The water-based EAU wear-resistant and anti-corrosion topcoat differs from that in Preparation Example 4.1 in that the raw materials and dosages are shown in Table 4, while the other steps are the same as in Preparation Example 4.1.

[0126] Example

[0127] Example 1

[0128] A method for repairing severely locally corroded steel plates includes the following steps:

[0129] S1. Clean the surface rust of the steel plate and divide the damaged area into areas to be repaired by extending 35cm outwards from the edge of the damaged area.

[0130] S2. Apply the water-based EAU rust-removing primer obtained in Preparation Example 1.1 to the area to be repaired, which converts the oxide rust on the steel plate surface into a strong complex. After drying and curing, a rust-removing primer layer is formed with a thickness of 30 μm.

[0131] S3. Apply the water-based EAU zinc-rich primer obtained in Preparation Example 2.1 to the surface of the rust-repellent primer layer, and after drying and curing, a zinc-rich primer layer is formed with a thickness of 50 μm.

[0132] S4. A non-woven fabric-impregnated waterborne EAU high-barrier intermediate coating is applied to the surface of a zinc-rich primer layer, and after drying and curing, a non-woven fabric-reinforced high-barrier layer is formed. The thickness of the non-woven fabric-reinforced high-barrier layer is 0.65 mm. The waterborne EAU high-barrier intermediate coating is obtained from Preparation Example 3.1.

[0133] S5. Lay a fiberglass geogrid on the non-woven fabric reinforced high barrier layer, surround the damaged area, and then pour water-based EAU high barrier intermediate coating onto the fiberglass geogrid. After drying and curing, a fiber geogrid reinforced load-bearing layer is formed with a thickness of 3.5mm.

[0134] S6. Finally, the water-based EAU wear-resistant and anti-corrosion topcoat obtained in Preparation Example 4.1 is applied to the surface of the fiber grid reinforced load-bearing layer. After drying and curing, a wear-resistant and anti-corrosion cover layer is formed, thus completing the repair. The thickness of the wear-resistant and anti-corrosion cover layer is 60 μm.

[0135] Example 2

[0136] A method for repairing severely locally corroded steel plates includes the following steps:

[0137] S1. Clean the surface rust of the steel plate and divide the damaged area into areas to be repaired by extending 10cm outwards from the edge of the damaged area;

[0138] S2. Apply the water-based EAU rust-removing primer obtained in Preparation Example 1.1 to the area to be repaired, which converts the oxide rust on the steel plate surface into a strong complex. After drying and curing, a rust-removing primer layer is formed with a thickness of 30 μm.

[0139] S3. Apply the water-based EAU zinc-rich primer obtained in Preparation Example 2.1 to the surface of the rust-repellent primer layer, and after drying and curing, a zinc-rich primer layer is formed with a thickness of 50 μm.

[0140] S4. A non-woven fabric-impregnated waterborne EAU high-barrier intermediate coating is applied to the surface of a zinc-rich primer layer, and after drying and curing, a non-woven fabric-reinforced high-barrier layer is formed. The thickness of the non-woven fabric-reinforced high-barrier layer is 1 mm. The waterborne EAU high-barrier intermediate coating is obtained from Preparation Example 3.1.

[0141] S5. Lay a fiberglass geogrid on the non-woven fabric reinforced high barrier layer, surround the damaged area, and then pour water-based EAU high barrier intermediate coating onto the fiberglass geogrid. After drying and curing, a fiber geogrid reinforced load-bearing layer is formed with a thickness of 3mm.

[0142] S6. Finally, the water-based EAU wear-resistant and anti-corrosion topcoat obtained in Preparation Example 4.1 is applied to the surface of the fiber grid reinforced load-bearing layer. After drying and curing, a wear-resistant and anti-corrosion cover layer is formed, thus completing the repair. The thickness of the wear-resistant and anti-corrosion cover layer is 60 μm.

[0143] Example 3

[0144] A method for repairing severely locally corroded steel plates includes the following steps:

[0145] S1. Clean the surface rust of the steel plate and divide the damaged area into areas to be repaired by extending 50cm outwards from the edge of the damaged area;

[0146] S2. Apply the water-based EAU rust-removing primer obtained in Preparation Example 1.1 to the area to be repaired, which converts the oxide rust on the steel plate surface into a strong complex. After drying and curing, a rust-removing primer layer is formed with a thickness of 30 μm.

[0147] S3. Apply the water-based EAU zinc-rich primer obtained in Preparation Example 2.1 to the surface of the rust-repellent primer layer, and after drying and curing, a zinc-rich primer layer is formed with a thickness of 50 μm.

[0148] S4. A non-woven fabric-impregnated waterborne EAU high-barrier intermediate coating is applied to the surface of a zinc-rich primer layer. After drying and curing, a non-woven fabric-reinforced high-barrier layer is formed. The thickness of the non-woven fabric-reinforced high-barrier layer is 0.5 mm. The waterborne EAU high-barrier intermediate coating is obtained from Preparation Example 3.1.

[0149] S5. Lay a fiberglass geogrid on the non-woven fabric reinforced high barrier layer, surround the damaged area, and then pour water-based EAU high barrier intermediate coating onto the fiberglass geogrid. After drying and curing, a fiber geogrid reinforced load-bearing layer is formed with a thickness of 5mm.

[0150] S6. Finally, the water-based EAU wear-resistant and anti-corrosion topcoat obtained in Preparation Example 4.1 is applied to the surface of the fiber grid reinforced load-bearing layer. After drying and curing, a wear-resistant and anti-corrosion cover layer is formed, thus completing the repair. The thickness of the wear-resistant and anti-corrosion cover layer is 60 μm.

[0151] Example 4

[0152] A method for repairing severely corroded steel plates, differing from Example 1 in that a water-based EAU rust-blocking primer is not applied to the area to be repaired, and the rust-blocking primer layer is absent from the repair structure of the steel plate. The method specifically includes the following steps:

[0153] S1. Clean the surface rust of the steel plate and divide the damaged area into areas to be repaired by extending 35cm outwards from the edge of the damaged area.

[0154] S2. Apply the water-based EAU zinc-rich primer obtained in Preparation Example 2.1 to the area to be repaired, and after drying and curing, a zinc-rich primer layer is formed with a thickness of 50 μm.

[0155] S3. A non-woven fabric-impregnated waterborne EAU high-barrier intermediate coating is applied to the surface of a zinc-rich primer layer, and after drying and curing, a non-woven fabric-reinforced high-barrier layer is formed. The thickness of the non-woven fabric-reinforced high-barrier layer is 0.65 mm. The waterborne EAU high-barrier intermediate coating is obtained from Preparation Example 3.1.

[0156] S4. Lay a fiberglass geogrid on the non-woven fabric reinforced high barrier layer, surround the damaged area, and then pour water-based EAU high barrier intermediate coating onto the fiberglass geogrid. After drying and curing, a fiber geogrid reinforced load-bearing layer is formed with a thickness of 3.5mm.

[0157] S5. Finally, the water-based EAU wear-resistant and anti-corrosion topcoat obtained in Preparation Example 4.1 is applied to the surface of the fiber grid reinforced load-bearing layer. After drying and curing, a wear-resistant and anti-corrosion cover layer is formed, thus completing the multi-layer repair system. The thickness of the wear-resistant and anti-corrosion cover layer is 60 μm.

[0158] Comparative Example

[0159] Comparative Example 1

[0160] A method for repairing a locally severely corroded steel plate, differing from Example 4 in that it does not use non-woven fabric for reinforcement, and the repair structure does not include a non-woven fabric-reinforced high-barrier layer. The method specifically includes the following steps:

[0161] S1. Clean the surface rust of the steel plate and divide the damaged area into areas to be repaired by extending 35cm outwards from the edge of the damaged area.

[0162] S2. Apply the water-based EAU zinc-rich primer obtained in Preparation Example 2.1 to the area to be repaired, and after drying and curing, a zinc-rich primer layer is formed with a thickness of 50 μm.

[0163] S3. A fiberglass geogrid is laid on the zinc-rich primer layer, and a barrier is built around the damaged area. Then, the water-based EAU high-barrier intermediate coating obtained in Preparation Example 3.1 is poured onto the fiberglass geogrid. After drying and curing, a fiber geogrid-reinforced load-bearing layer is formed with a thickness of 4.5 mm.

[0164] S4. Finally, the water-based EAU wear-resistant and anti-corrosion topcoat obtained in Preparation Example 4.1 is applied to the surface of the fiber grid reinforced load-bearing layer. After drying and curing, a wear-resistant and anti-corrosion topcoat is formed, thus forming a multi-layer repair system, which completes the repair. The thickness of the wear-resistant and anti-corrosion topcoat is 60 μm.

[0165] Comparative Example 2

[0166] A method for repairing a severely corroded steel plate, differing from Example 4 in that it does not use fiberglass geogrid for reinforcement, and the repair structure does not include a fiberglass geogrid reinforced load-bearing layer. The method specifically includes the following steps:

[0167] S1. Clean the surface rust of the steel plate and divide the damaged area into areas to be repaired by extending 35cm outwards from the edge of the damaged area.

[0168] S2. Apply the water-based EAU zinc-rich primer obtained in Preparation Example 2.1 to the area to be repaired, and after drying and curing, a zinc-rich primer layer is formed with a thickness of 50 μm.

[0169] S3. A non-woven fabric-impregnated waterborne EAU high-barrier intermediate coating is applied to the surface of a zinc-rich primer layer, and after drying and curing, a non-woven fabric-reinforced high-barrier layer is formed. The thickness of the non-woven fabric-reinforced high-barrier layer is 0.65 mm. The waterborne EAU high-barrier intermediate coating is obtained from Preparation Example 3.1.

[0170] S4. Finally, the water-based EAU wear-resistant and anti-corrosion topcoat obtained in Example 4.1 is applied to the surface of the non-woven fabric reinforced high barrier layer. After drying and curing, a wear-resistant and anti-corrosion topcoat is formed, thus forming a multi-layer repair system, and the repair is completed. The thickness of the wear-resistant and anti-corrosion topcoat is 60 μm.

[0171] Comparative Example 3

[0172] A method for repairing locally severely corroded steel plates, differing from Example 4 in that it does not use non-woven fabric and fiberglass geogrid for reinforcement, specifically includes the following steps:

[0173] S1. Clean the surface rust of the steel plate and divide the damaged area into areas to be repaired by extending 35cm outwards from the edge of the damaged area.

[0174] S2. Apply the water-based EAU zinc-rich primer obtained in Preparation Example 2.1 to the area to be repaired, and after drying and curing, a zinc-rich primer layer is formed with a thickness of 50 μm.

[0175] S3. Apply the water-based EAU high-barrier intermediate coating obtained in Example 3.1 to the surface of the zinc-rich primer layer, and after drying and curing, form a high-barrier reinforcement layer with a thickness of 0.65 mm.

[0176] S4. Finally, the water-based EAU wear-resistant and anti-corrosion topcoat obtained in Preparation Example 4.1 is applied to the surface of the high-barrier reinforcement layer. After drying and curing, a wear-resistant and anti-corrosion topcoat is formed, thus forming a multi-layer repair system, which completes the repair. The thickness of the wear-resistant and anti-corrosion topcoat is 60 μm.

[0177] Comparative Example 4

[0178] A method for repairing a steel plate with severe localized corrosion differs from Example 4 in that water-based EAU wear-resistant and anti-corrosion topcoat is not applied to the area to be repaired, and the repair structure of the steel plate does not contain a wear-resistant and anti-corrosion cover layer. All other steps are the same as in Example 4.

[0179] Performance testing

[0180] Seven steel plates with similar localized severe rust and damage were selected as test samples. The repair methods of Comparative Examples 1-4 in Examples 1-4 were used to repair the eight steel plate samples. The repaired steel plates were then subjected to the following relevant performance tests, and the test results are recorded in Table 5.

[0181] 1. Impermeability: Referring to GB / T 16777-2008 "Test Methods for Waterproof Coatings for Buildings", the repaired steel plate sample was fixed in the impermeability test device, a pressure of 0.4 MPa was applied to the sample surface, and the pressure was maintained for 2 hours. The back of the steel plate sample was observed to see if water penetration occurred. The test results were recorded in Table 5.

[0182] 2. Tensile bond strength: Referring to CECS 343:2013 "Technical Specification for Application of Anti-corrosion Coatings for Steel Structures", tensile viscosity strength tests were performed on the surface of the repaired steel plate samples. A result of ≥2MPa was considered qualified. Each group of tests was conducted 3 times, and the average value was taken as the final result. The test results were recorded in Table 5.

[0183] 3. Impact resistance: Refer to GB / T 1732-1993 "Test Method for Impact Resistance of Coating Film", a 1000g steel ball is dropped from a height of 100cm to impact the surface of the repaired steel plate sample. Observe whether cracks, peeling or other phenomena appear on the surface of the steel plate sample, and record the test results in Table 5. The coating is qualified if there are no cracks or peeling.

[0184] 4. Abrasion resistance test: Refer to GB / T 1768-2006 "Determination of abrasion resistance of paints and varnishes - Rotary rubber grinding wheel method", use an abrasion resistance tester, apply a 750g load to the grinding wheel, set the rotation speed to 500 rpm to wear the surface of the steel plate sample, record the average mass loss, and the result ≤0.03g is qualified.

[0185] 5. Liquid media resistance test: Refer to GB / T 9274-1988 "Determination of resistance to liquid media of coatings", immerse steel plate samples in 30% hydrochloric acid solution for 48h, 30% sulfuric acid solution for 48h and 40% sodium hydroxide solution for 72h respectively, and observe whether bubbles, cracks, discoloration or other phenomena appear on the surface of the steel plate samples. The coating is qualified if there are no bubbles, cracks or discoloration.

[0186] Table 5

[0187]

[0188]

[0189] As can be seen from the performance test results in Table 5, the repair method for locally severely corroded steel plates of this application can effectively repair steel plates with severe local corrosion and damage. Moreover, there is no safety risk in the repair process, and the repaired steel plate has good load-bearing capacity and corrosion resistance, and can work safely and reliably.

[0190] Performance tests conducted on the steel plates repaired using the repair methods described in Examples 1-4 and Comparative Examples 1-4 show that both the non-woven fabric-reinforced waterborne EAU high-barrier intermediate coating and the glass fiber geogrid-reinforced waterborne EAU high-barrier intermediate coating can effectively enhance the overall load-bearing capacity of the steel plates and reduce the risk of further deformation or damage. By designing the thickness of the glass fiber geogrid, the load-bearing capacity of the multi-layer repair system can be adjusted.

[0191] The addition of a rust-blocking primer layer allows the two primer layers, the rust-blocking primer layer and the zinc-rich primer layer, to complement each other, which significantly improves the repair effect of the repair method in this application when repairing steel plates that are severely rusted to the point that rust removal is impossible. This results in the repaired steel plate having excellent corrosion resistance and load-bearing capacity.

[0192] The water-based EAU wear-resistant and anti-corrosion topcoat forms a wear-resistant and anti-corrosion coating that effectively improves the durability and wear resistance of the repaired areas of the steel plate, preventing further damage to the steel plate.

[0193] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for repairing severely locally corroded steel plates, characterized in that, Includes the following steps: S1. Clean the surface rust of the steel plate and delineate the area to be repaired by extending the edge of the damaged part outwards. S2. Apply water-based EAU rust-curing primer to the area to be repaired, and after drying and curing, a rust-curing primer layer is formed. The raw materials of the water-based EAU rust-curing primer include a composite emulsion and a curing component. The curing component includes aminotrimethylene phosphonic acid and zinc phosphate. S3. Apply water-based EAU zinc-rich primer to the rust-removing primer layer, and after drying and curing, form a zinc-rich primer layer. The raw materials of the water-based EAU zinc-rich primer include composite emulsion, curing component and powder component. The powder component includes zinc powder and nano calcium carbonate. S4. A non-woven fabric is used to impregnate a water-based EAU high-barrier intermediate coating, which is then adhered to the surface of a zinc-rich primer layer. After drying and curing, a non-woven fabric-reinforced high-barrier layer is formed. The raw materials of the water-based EAU high-barrier intermediate coating include a composite emulsion, a curing component, and reinforcing powder. The reinforcing powder includes slag powder, steel slag powder, and sodium silicate. S5. Lay fiberglass geogrid, surround the damaged area, then pour water-based EAU high-barrier intermediate coating, and after drying and curing, form a fiber geogrid reinforced load-bearing layer. S6. Finally, apply water-based EAU wear-resistant and anti-corrosion topcoat to the surface of the fiber grid reinforced load-bearing layer. After drying and curing, a wear-resistant and anti-corrosion topcoat is formed, creating a multi-layer repair system, thus completing the repair. The raw materials of the water-based EAU wear-resistant and anti-corrosion topcoat include composite emulsion, curing components, and reinforcing powder. The reinforcing powder includes silicon carbide and nano-silica.

2. The repair method for severely corroded steel plates according to claim 1, characterized in that, The raw materials of the water-based EAU rust-curing primer include a composite emulsion and a curing component; The composite emulsion comprises 90-110 parts by weight of waterborne EAU composite resin emulsion; the curing component comprises 12-16 parts of curing agent, 0.1-0.3 parts of wetting agent, 0.2-0.5 parts of dispersant, 0.2-0.5 parts of defoamer, 0.6-1.2 parts of film-forming aid, 12.5-17.5 parts of aminotrimethylenephosphonic acid, 11-16 parts of zinc phosphate, 5-9 parts of aluminum tripolyphosphate and 25-35 parts of water.

3. The repair method for severely corroded steel plates according to claim 1, characterized in that, The raw materials of the waterborne EAU zinc-rich primer include a composite emulsion, a curing component, and a powder component. By weight, the composite emulsion includes 90-110 parts of waterborne EAU composite resin emulsion; the curing component includes 12-16 parts of curing agent, 0.1-0.3 parts of wetting agent, 0.3-0.6 parts of dispersant, 0.2-0.5 parts of defoamer, 0.6-1 parts of film-forming aid, and 25-35 parts of water; the powder component includes 59-67 parts of zinc powder and 3-5 parts of nano-calcium carbonate.

4. The repair method for severely corroded steel plates according to claim 1, characterized in that, The raw materials of the waterborne EAU high-barrier intermediate coating include a composite emulsion, a curing component, and a reinforcing powder. By weight, the composite emulsion includes 80-100 parts of waterborne EAU composite resin emulsion; the curing component includes 11.2-15.7 parts of curing agent, 0.1-0.3 parts of wetting agent, 0.2-0.5 parts of dispersant, 0.2-0.5 parts of defoamer, 0.6-1.2 parts of film-forming aid, 0.3-0.6 parts of anti-settling agent, 0.3-0.6 parts of cellulose ether, and 32-38 parts of water; the reinforcing powder includes 15.6-22.4 parts of slag powder, 3-7 parts of steel slag powder, and 1.2-1.9 parts of sodium silicate.

5. The repair method for locally severely corroded steel plates according to claim 1, characterized in that, The raw materials of the water-based EAU wear-resistant and anti-corrosion topcoat include a composite emulsion, a curing component, and a reinforcing powder. By weight, the composite emulsion includes 80-100 parts of water-based EAU composite resin emulsion; the curing component includes 11-14 parts of curing agent, 0.2-0.4 parts of wetting agent, 0.2-0.4 parts of dispersant, 0.2-0.5 parts of defoamer, 0.5-0.8 parts of film-forming aid, 0.2-0.4 parts of leveling agent, 5-8 parts of water-based colorant, and 25-32 parts of water; the reinforcing powder includes 2.5-5.5 parts of silicon carbide and 3-7 parts of nano-silica.

6. The method for repairing locally severely corroded steel plates according to any one of claims 2-5, characterized in that, The curing agent is any one or a combination of two of the following: waterborne polyurea resin or polyisocyanate curing agent.

7. The repair method for severely corroded steel plates according to claim 1, characterized in that, The area to be repaired is an area extending 10-50cm outwards from the edge of the damaged part.

8. The method for repairing locally severely corroded steel plates according to claim 1, characterized in that, The thickness of the nonwoven fabric reinforced high-barrier layer is 0.5-1mm, and the thickness of the fiber grid reinforced load-bearing layer is 3-5mm.

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