Surface treatment method for prolonging service life of road, bridge and culvert cement concrete structure

Abstract

The invention discloses a surface treatment method for prolonging the service life of a road, bridge and culvert cement concrete structure, and belongs to the technical field of protection and life prolonging. According to the method, a three-component composite coating system is adopted and comprises a silane coupling agent pretreatment layer, a polyurethane transition layer and a fluorocarbon resin surface layer. The silane coupling agent is connected with the concrete matrix and the polyurethane transition layer through chemical bonds, and the polyurethane transition layer further reacts with the fluorocarbon resin through active groups to form the high-adhesion coating. By optimizing the formula and the process, the corrosion resistance, the wear resistance, the impermeability and the weather resistance of the coating are remarkably improved, erosion media such as acid, alkali, salt and water can be effectively prevented from invading, the service life of a concrete structure is prolonged by 10-20 years, the service cost of the whole service life is reduced by 20-30%, and the coating is suitable for protection of traffic infrastructures such as viaducts, tunnels and culverts.

Description

Technical Field

[0001] The present invention relates to the technical field of protection and life extension of cement concrete structures for road bridges and culverts, and particularly relates to a high-corrosion-resistant surface treatment method based on a composite coating system, which is especially suitable for the protection of traffic infrastructure such as viaducts, tunnels, and culverts to improve their weather resistance, chemical corrosion resistance, and mechanical properties. Background Art

[0002] In the modern transportation system, as key infrastructure, the durability of the cement concrete structures of road bridges and culverts plays a decisive role in the safety and service life of the road bridge system. Currently, with the continuous growth of traffic flow and the increasing vehicle load, coupled with the erosion of complex environmental factors, the cement concrete structures of road bridges and culverts are facing severe challenges.

[0003] In sections such as viaducts and tunnels of urban expressways, rain and snow weather is frequent. To ensure vehicle passage, brine is often used to accelerate snow melting, and the salt will strongly corrode the concrete structure. Carbon dioxide, hydrocarbons, nitrogen oxides, etc. in automobile exhaust mix with moisture in the air to form an acid, which falls on the concrete surface and causes corrosion. And the culvert is underground. In addition to the above-mentioned erosion, it is also threatened by water seepage all year round. Under the long-term action of acids, alkalis, salts, and moisture, the concrete is prone to powdering and cracking, accelerating aging, and significantly shortening the service life. At the same time, the dynamic load and vibration brought by vehicle driving cause micro-cracks on the concrete surface, further providing channels for the intrusion of corrosive media, forming a vicious cycle and accelerating the structural damage. Therefore, it is extremely urgent to improve the service life of the cement concrete structures of road bridges and culverts. Summary of the Invention

[0004] The present invention aims to improve the bonding performance between the coating and the concrete matrix through innovative coating material formulations and optimized construction processes, enhance the corrosion resistance, wear resistance, and impermeability of the coating, effectively prevent the intrusion of external corrosive media, thereby significantly improving the service life of the cement concrete structures of road bridges and culverts, ensuring the safe and stable operation of road bridge infrastructure, reducing maintenance costs and the risk of traffic interruption, and meeting the requirements of modern traffic engineering for durability and reliability.

[0005] The present invention adopts the following technical solutions:

[0006] A surface treatment method for improving the service life of the cement concrete structure of a road bridge and culvert, comprising the following steps:

[0007] S1: Pretreat the surface of the cement concrete to ensure that the surface is dry, clean and meets the following conditions: surface humidity ≤ 10%, pH value < 10, no hollowing and loosening.

[0008] S2: Spray the silane coupling agent solution, and its mass formulation ratio is silane coupling agent: acetic acid: water: alcohol = (1 - 5):(1 - 5):(1 - 5):(75 - 97);

[0009] S3: After air-drying the solution sprayed in step S2, grind the base layer to ensure the surface is flat and free of oil stains;

[0010] S4: Spray the polyurethane transition layer, and its mass formulation ratio is polyurethane prepolymer: silane coupling agent: ethyl acetate: methyl ethyl ketone = (5 - 10):(1 - 2):(44 - 47):(44 - 47);

[0011] S5: Spray the fluorocarbon resin surface layer on the surface of the polyurethane transition layer. The fluorocarbon resin is one of modified polyvinylidene fluoride or polytetrafluoroethylene, and the modification method is to introduce active oxygen by the plasma method and generate hydroxyl groups through a hydrogenation reaction;

[0012] S6: Air-dry and cure the fluorocarbon resin surface layer to form a composite coating structure.

[0013] Preferably, the surface pretreatment in step S1 includes:

[0014] 1) Use a neutral cleaner or solvent to remove grease and dirt;

[0015] 2) After removing mold or moss with high-pressure water, treat with a mildew-proof solution;

[0016] 3) Embed and seal the cracks and pipe roots and make additional waterproof treatment.

[0017] Preferably, the silane coupling agent in step S2 is selected from one or several mixtures of KH550, KH560, KH570 or Nanda 42.

[0018] Preferably, the polyurethane transition layer in step S4 is a polyurethane prepolymer containing active isocyanate groups, and it is selected from one or several of the reaction prepolymers of trimethylolpropane / TDI, glycerol / TDI or castor oil / TDI.

[0019] Preferably, after spraying the silane coupling agent solution in step S2, it needs to be ground with a angle grinder until the base layer is flat and has no sharp unevenness, and the coupling agent solution is replenished by brushing at the grinding area.

[0020] Preferably, before spraying the polyurethane transition layer in step S4, it is necessary to ensure that the base layer is dry and pollution-free. After spraying, the peeling or damaged areas need to be sandblasted to Sa2 1 / 2 level in GB8923 - 8, and the primer is repaired.

[0021] Preferably, the spraying method of the silane coupling agent solution in step S2 is one of air spraying, high-pressure airless spraying or brushing process; the spraying method of the fluorocarbon resin surface layer in step S5 is one of air spraying, high-pressure airless spraying or brushing process.

[0022] Preferably, the curing time of the fluorocarbon resin surface layer in step S6 is 48 hours, and the construction environment temperature is controlled at 5-35°C.

[0023] The technical solution of the present invention has the following advantages compared with the prior art:

[0024] A. Through the innovative three-component coating material formula and construction process, the present invention improves the bonding performance between the coating and the concrete matrix, enhances corrosion resistance, wear resistance and impermeability, effectively prevents the intrusion of external corrosive media, and increases the service life of the cement concrete structure by 10-20 years. It reduces the need for frequent repair or replacement due to structural damage, and the overall life cycle cost is reduced by 20-30%.

[0025] B. Excellent weather resistance: The fluorine atoms in the fluorocarbon resin have strong chemical stability, can resist the erosion of ultraviolet rays, oxygen, moisture, etc., and can maintain performance, color and luster outdoors for a long time, reducing coating aging and structural damage caused by climate factors.

[0026] C. Excellent chemical corrosion resistance: It has strong resistance to chemical substances such as acids, alkalis and salts, can effectively protect the cement concrete structure in the transportation field, and resist the erosion of acidic substances formed by brine and vehicle exhaust in urban roads.

[0027] D. Good self-cleaning property: The surface of the fluorocarbon resin is smooth, not easily contaminated with dust and dirt and is easy to clean, reducing the maintenance cost of the structure and the frequency and workload of manual cleaning.

[0028] E. Reliable mechanical properties: The fluorocarbon resin has high hardness and strong adhesion, can effectively resist mechanical damage caused by vehicle driving, protect the surface integrity of the cement concrete structure, and reduce the risk of cracks and damage caused by mechanical action. Specific embodiments

[0029] The present invention can be implemented in many different forms and should not be construed as limited to the embodiments set forth herein. On the contrary, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the present invention to those skilled in the art. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0030] The present invention discloses a surface treatment method for improving the service life of cement concrete structures of road and bridge culverts, including the following steps:

[0031] S1: Pretreat the surface of the cement concrete to ensure that the surface is dry, clean and meets the following conditions: surface humidity ≤ 10%, pH value < 10, no hollowing or loosening;

[0032] S2: Spray a silane coupling agent solution. The silane coupling agent is selected from one or more of KH550, KH560, KH570 or Nanda 42, and its formulation ratio is silane coupling agent: acetic acid: water: alcohol = (1 - 5):(1 - 5):(1 - 5):(75 - 97);

[0033] S3: After air-drying the solution sprayed in step S2, grind the base layer to ensure that the surface is flat and free of oil stains;

[0034] S4: Spray a polyurethane transition layer. The polyurethane transition layer is a polyurethane prepolymer containing active isocyanate groups, which is selected from one or more of trimethylolpropane / TDI reaction prepolymer, glycerol / TDI reaction prepolymer or castor oil / TDI reaction prepolymer, and its formulation ratio is polyurethane prepolymer: silane coupling agent: ethyl acetate: methyl ethyl ketone = (5 - 10):(1 - 2):(44 - 47):(44 - 47);

[0035] S5: Spray a fluorocarbon resin surface layer on the surface of the polyurethane transition layer. The fluorocarbon resin is one of modified polyvinylidene fluoride or polytetrafluoroethylene, and the modification method is to introduce active oxygen by plasma method and generate hydroxyl groups through hydrogenation reaction;

[0036] S6: Air-dry the fluorocarbon resin surface layer and cure it for 48 hours to form a composite coating structure.

[0037] This application mainly uses three components to treat the cement concrete structure, one is a silane coupling agent, one is a polyurethane transition layer, and one is a fluorocarbon resin surface layer; first, use a silane coupling agent solution containing amino groups to treat its surface. The silane coupling agent contains active inorganic groups and organic groups, and uses these two active groups to build a connecting bridge between the cement concrete structure and the organic coating; the active inorganic siloxy group therein generates a chemical reaction with the siloxy group in the cement concrete to form a firm bond; the active amino group at the other end of the silane coupling agent generates a chemical reaction with the isocyanate group of the polyurethane in the next transition layer and is firmly bonded to the cement concrete structure through chemical bonds to form a highly elastic active transition layer; there are active isocyanate groups retained on the transition layer, which react with the grafted active hydroxyl groups of the highly weather-resistant and highly corrosion-resistant fluorocarbon paint sprayed on the surface to generate chemical bonds, making it firmly bonded to the surface of the transition layer, greatly improving the adhesion of the fluorocarbon paint film, firmly bonded to the surface of the cement concrete, protecting the cement concrete structure by the fluorocarbon paint, and its service life can be increased by 10 - 20 years, and the total life cycle usage cost can be reduced by 20 - 30%.

[0038] When using this method for surface treatment of the cement concrete structure of road and bridge culverts, the following conditions shall also be met:

[0039] (1) Before use, repair obvious surface damages, and there shall be no phenomena such as hollowing and looseness. When a demoulding agent is used for the concrete structure, it shall be determined through spraying experiments that it has no influence on the silane concrete protective agent, or the surface to be protected shall be fully treated and cleaned before spraying. Clean the concrete surface and remove the alkali scale and dirt on the surface to be treated. For maximum penetration into the substrate, construction shall be carried out on a dry surface, and it shall wait until the substrate surface is dry.

[0040] (2) The cement concrete surface shall meet the following requirements: 1) Ensure that the painted surface is fully dry, and the concrete surface shall have a sufficient curing period. 2) The surface humidity shall be below 10%. 3) The alkaline pH value of the concrete surface shall be less than 10. 4) Remove fine grease dirt and powder with a neutral cleaner or solvent, or wipe it with a wet cloth to thoroughly remove all stains. 5) Remove the mildew or moss growing on the wall with high-pressure water, treat it with a mildew-proof solution, then wash it with clean water and dry it.

[0041] (3) Spray the coupling agent solution on the construction surface by using conventional air spraying or high-pressure airless spraying. The brushing process is used for repair operations, which is used for pre-coating and small-area painting, or when local spraying is not in place during spraying construction.

[0042] (4) Grind the base layer sprayed with the coupling agent flat with a angle grinder to ensure its firmness and dryness, without sharp unevenness, honeycombing, pitted surface and peeling, and without oil stains. For the cracks, base layer deformation joints, and grooves left at the pipe roots, sealant shall be embedded and additional waterproof treatment shall be done. For a flat and solid base layer, no base layer treatment agent needs to be applied. For a loose and porous base surface, construction under high temperature, high humidity or sun exposure environment, use a special base layer treatment agent, which can greatly improve the quality of the on-site construction coating film.

[0043] (5) Spray the polyurethane transition layer by using conventional air spraying or high-pressure airless spraying. The brushing process is used for repair operations, pre-coating and small-area painting.

[0044] (5) The surface of the polyurethane transition layer shall be clean, dry, free of grease, rust and other dirt, and the surface shall be evaluated and treated in accordance with ISO8504.

[0045] (7) The surface of the polyurethane transition layer shall be dry, pollution-free, and must be painted within the specified recoating interval.

[0046] (8) The peeling and damaged areas shall be sandblasted to reach Sa2 1 / 2 of GB8923-8. Prime coat repair shall be carried out on these parts before applying the flexible fluorocarbon coating.

[0047] (9) Spray flexible fluorocarbon paint using conventional air spraying process or high-pressure airless spraying process, and use brushing process for repair work, pre-coating and small-area coating.

[0048] Example 1:

[0049] Use the method of this application to carry out protection construction on the concrete of a certain viaduct, specifically as follows:

[0050] S1. Surface pretreatment: Remove the dirt on the concrete surface, dry it to a humidity < 10% after high-pressure water washing, and adjust the pH value to 7.5.

[0051] S2 - S3. Spray silane coupling agent: Use KH560 solution (ratio 2:3:2:93), spray twice by high-pressure airless spraying, and polish it flat after drying.

[0052] S4. Coat polyurethane transition layer: Select castor oil / TDI prepolymer (ratio 8:1.5:45:45.5), dry for 4 hours after spraying.

[0053] S5 - S6. Spray fluorocarbon resin: Use plasma-modified polyvinylidene fluoride, spray twice, and cure for 48 hours.

[0054] Effect verification: After 3 years of tracking and detection, the coating has no cracking or peeling, and the carbonation depth of the concrete is only 0.2 mm, which is significantly better than the untreated area (1.5 mm).

[0055] Example 2:

[0056] Use the method of this application to carry out protection construction on a certain culvert structure, specifically as follows:

[0057] Adjust the silane coupling agent to KH570 (ratio 4:2:4:90), and the other steps are the same as in Example 1. The result shows that the water resistance is improved by 30%, and the seepage rate is lower than 0.01%.

[0058] The above examples confirm that the method of the present invention can significantly improve the durability of bridge and culvert structures and meet the long-term protection requirements under complex environments.

[0059] What is not described in the present invention applies to the prior art.

[0060] Obviously, the above examples are only for clear illustration and are not limitations on the implementation methods. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A surface treatment method for improving the service life of cement concrete structures of bridges and culverts, characterized in that: The following steps are involved: S1: Pre-treat the cement concrete surface to ensure that the surface is dry, clean and meets the following conditions: surface humidity ≤ 10%, pH value < 10, no hollowing or looseness; S2: spraying a silane coupling agent solution, wherein the formula ratio is silane coupling agent: acetic acid: water: alcohol = (1-5): (1-5): (1-5): (75-97); S3: After the solution sprayed in step S2 is dried, the base layer is polished to ensure that the surface is flat and free of oil stains; S4: spraying a polyurethane transition layer, wherein the formula ratio is polyurethane prepolymer: silane coupling agent: ethyl acetate: butanone = (5-10): (1-2): (44-47): (44-47); S5: spraying a fluorocarbon resin surface layer on the surface of the polyurethane transition layer, wherein the fluorocarbon resin is one of modified polyvinylidene fluoride or polytetrafluoroethylene, and the modification method is to introduce active oxygen by a plasma method and generate hydroxyl groups by hydrogenation reaction; S6: Dry and cure the fluorocarbon resin surface layer to form a composite coating structure.

2. The surface treatment method according to claim 1, characterized in that: The surface pretreatment in step S1 includes: 1) Use a neutral detergent or solvent to remove grease and dirt; 2) After high-pressure water is used to remove mold or moss, it is treated with an anti-mold solution; 3) Fill the cracks and pipe roots with sealing materials and perform additional waterproofing treatment.

3. The surface treatment method according to claim 1, characterized in that: The silane coupling agent in step S2 is selected from one or a mixture of KH550, KH560, KH570 or Nanda 42.

4. The surface treatment method according to claim 1, characterized in that: The polyurethane transition layer in step S4 is a polyurethane prepolymer containing an active isocyanate group, which is selected from one or more of trimethylolpropane / TDI reaction prepolymer, glycerol / TDI reaction prepolymer or castor oil / TDI reaction prepolymer.

5. The surface treatment method according to claim 1, characterized in that: In the step S2, after the silane coupling agent solution is sprayed, it needs to be polished by an angle grinder until the base layer is flat and has no sharp bumps, and the coupling agent solution is brushed on the polished area.

6. The surface treatment method according to claim 1, characterized in that: Before spraying the polyurethane transition layer in step S4, the base layer must be dry and free of pollution. After spraying, the peeled or damaged area must be sandblasted to Sa2 in GB8923-8. 1 / 2 level, and touch up primer.

7. The surface treatment method according to claim 1, characterized in that: In step S2, the silane coupling agent solution is sprayed by air spraying, high-pressure airless spraying or brushing; in step S5, the fluorocarbon resin surface layer is sprayed by air spraying, high-pressure airless spraying or brushing.

8. The surface treatment method according to claim 1, characterized in that: In step S6, the curing time for the fluorocarbon resin surface layer is 48 hours, and the construction environment temperature is controlled at 5-35°C.