Marine concrete surface repair coating in seawater immersion environment and construction method thereof

Abstract

This invention belongs to the field of water conservancy and waterway engineering maintenance technology, specifically relating to a repair coating for the concrete surface of a ship lock in a seawater immersion environment and its construction method. The repair coating is applied to the surface of the ship lock concrete and includes, from the inside out, a penetrating and anchoring primer, a stress-buffering intermediate layer, and an ultra-weather-resistant protective topcoat. The penetrating and anchoring primer is a two-component epoxy-biomineralization composite system. The construction method of the repair coating includes the following steps: substrate diagnosis and cleaning; negative pressure microenvironment construction; in-situ vacuum dehydration and resistance removal; negative pressure primer introduction; controlled ventilation and re-pressure penetration; and multi-layer system construction. This invention can overcome capillary water wedge resistance and achieve deep penetration and high-strength anchoring of the repair material into micro-cracks in concrete without requiring long-term navigation stoppage for substrate drying, significantly improving the chloride ion penetration resistance and durability of the ship lock structure.

Description

Technical Field

[0001] This invention belongs to the field of water conservancy and waterway engineering maintenance technology, and in particular relates to a repair coating for the concrete surface of a ship lock in a seawater immersion environment and its construction method. Background Technology

[0002] Ship locks are crucial hubs connecting inland waterways and the sea. They are box-shaped hydraulic structures used to ensure the smooth passage of ships through concentrated water level differences in waterways. By pumping water in and out of the channel controlled by locks at both ends, the water level is raised or lowered, allowing ships to overcome these differences. The reliability of the lock's concrete is directly related to the lock's safety; therefore, it is essential to promptly identify and repair any defects in the concrete. Ship lock concrete structures are subjected to harsh conditions such as long-term seawater immersion, alternating wet and dry periods, freeze-thaw cycles, and ship impacts. Chloride ion corrosion in seawater, leading to steel reinforcement corrosion, is the primary cause of durability failure in lock concrete. This is because the high concentration of chloride ions in seawater allows them to gradually penetrate the concrete over time, causing structural cracking and damage, exposing internal components, reducing the structure's load-bearing capacity and service life, and even threatening collapse.

[0003] Existing technologies for repairing ship lock concrete have the following main drawbacks: 1. Adhesion failure on damp substrates: Ship locks have short maintenance windows, and even after the water is drained, the concrete remains saturated with water, often accompanied by seepage pressure on the back side. Traditional epoxy coatings are prone to "false adhesion," blistering, and peeling on damp substrates. 2. Insufficient penetration depth: Traditional manual roller coating or spraying processes rely solely on capillary action for penetration. For water-filled microcracks (<0.1mm), high-viscosity resins struggle to overcome the "water wedge" and "air resistance" effects, resulting in the coating merely floating on the surface, which is highly susceptible to separation under stress. 3. Limited construction conditions: To ensure the substrate is dry, prolonged navigation is often required, along with the construction of cofferdams and the use of high-power drying equipment, resulting in significant engineering costs.

[0004] Chinese patent CN101619201A discloses an underwater epoxy adhesive and its preparation method, which improves underwater bonding performance by using a specifically compounded modified amine curing agent. However, this technology mainly relies on manual application or grouting, which is a passive bonding method. In the actual working conditions of lock repair, the interior of concrete microcracks is often filled with pressurized water or saturated pore water. Relying solely on the wettability of the material itself is difficult to overcome capillary pressure and water wedge resistance, resulting in the repair material only adhering to the surface of the substrate and unable to penetrate deep into the cracks. Once subjected to ship impact or internal vapor pressure, the surface repair material is very easy to peel off completely, i.e., the skin and flesh separate.

[0005] Chinese patent CN103321420A discloses a vacuum-assisted grouting device and method for gamma-shaped prestressed pipes, which utilizes a vacuum pump to extract air from the pipe to assist in grout filling. Although this technology utilizes the principle of negative pressure, it is mainly aimed at enclosed pipe spaces and uses cement-based grout. For open, vertical lock walls, and scenarios requiring surface anti-corrosion coating construction, there is currently a lack of mature portable vacuum adsorption and permeation equipment and supporting chemical material systems.

[0006] Chinese patent CN120682698A discloses a low-temperature curing anti-corrosion coating and its preparation method. It solves the problem of low-temperature curing below -10℃ by using a modified phenolic amine curing agent. However, it is mainly for corrosion protection in atmospheric environments and lacks an active enhancement mechanism for underwater or damp substrates. Furthermore, its filler system (mica powder, iron oxide red) focuses on shielding rather than deep anchoring.

[0007] Chinese patent CN111042232A discloses a device and construction method for cleaning and repairing cracks in underwater membrane bag concrete walls. It introduces the concepts of vacuum adsorption and grouting. However, the device mainly relies on robotic arms and electromagnetic gun heads for local point repairs. It is suitable for membrane bag concrete with specific structures, but it is difficult to apply to the overall protection of large areas and uneven lock walls. Moreover, it focuses on "grouting" rather than "coating penetration".

[0008] Chinese patent CN117051775A discloses an underwater repair method and structure for hydraulic concrete cracks. It follows the traditional "grooving-pipe embedding-sealing-grouting" process, which is mainly aimed at large through cracks. It is powerless to strengthen the overall structure of widely distributed surface micro-cracks and concrete pores.

[0009] In addition, traditional construction methods usually require the concrete substrate to have a moisture content of less than 4%, which requires long-term closure of navigation and the construction of cofferdams for drying, resulting in extremely high project costs and seriously affecting navigation efficiency.

[0010] Therefore, developing a technology that can be applied to a partially dry substrate and actively press the repair material into the depths of microcracks using physical negative pressure to achieve deep anchoring and integrated repair is a pressing problem that needs to be solved. Summary of the Invention

[0011] To address the aforementioned problems, the present invention aims to provide a repair coating for the concrete surface of a ship lock in a seawater immersion environment and its construction method. This coating can overcome capillary water wedge resistance and achieve deep penetration (>3mm) and high-strength anchoring of the repair material into micro-cracks in the concrete without requiring long-term shutdown to dry the base surface, thereby significantly improving the resistance to chloride ion penetration and durability of the ship lock structure.

[0012] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0013] A repair coating for the surface of ship lock concrete in a seawater immersion environment is provided on the surface of the ship lock concrete. It comprises, from the inside out, a penetrating anchoring undercoat, a stress-buffering intermediate coat, and an ultra-weather-resistant protective topcoat. The penetrating anchoring undercoat is a two-component epoxy-biomineralization composite system, formed by uniformly mixing component A and component B at a weight ratio of 10:4-6. By weight, component A includes the following raw materials: 60-85 parts of a compound system of hyperbranched modified epoxy resin and bisphenol F type epoxy resin; 15-30 parts of reactive diluent; 0.2-0.5 parts of wetting and leveling agent; and 0.1-0.3 parts of defoamer. By weight, component B includes the following raw materials: 35-60 parts of Mannich base-modified cashew phenol aldehyde amine curing agent; 5-15 parts of nearshore biomass active aggregate; 3-8 parts of microencapsulation system; 1-3 parts of silane coupling agent; and 0.5-2.0 parts of accelerator.

[0014] Furthermore, in the above-mentioned component A, the epoxy equivalent of the hyperbranched modified epoxy resin is controlled at 165-175 g / eq, and the viscosity at 25°C is 800-1200 mPa·s.

[0015] Furthermore, in the above-mentioned component A, the epoxy equivalent of the bisphenol F type epoxy resin is 160-170 g / eq, and the viscosity at 25°C is 2000-4000 mPa·s.

[0016] Furthermore, in component A above, the active diluent is one or more of C12-C14 alkyl glycidyl ether and 1,4-butanediol diglycidyl ether.

[0017] Furthermore, in the above-mentioned component B, the amine value of the Mannich base-modified cashew phenol aldehyde amine curing agent is 300-500 mgKOH / g, the viscosity at 25℃ is 1000-3000 mPa·s, and the active hydrogen equivalent is 95-110.

[0018] Furthermore, in the aforementioned component B, the nearshore biomass active aggregate is nearshore biomass calcium carbonate aggregate that has undergone surface cleaning treatment. The aggregate has a particle size of 45–150 μm, and the heavy metal leaching concentration meets the Class I standard of GB 3097-1997 "Seawater Quality Standard" (Pb<0.001 mg / L, Cd<0.0001 mg / L, Hg<0.00005 mg / L). The aggregate includes at least one of the following: waste oyster shell powder, scallop shell powder, or coral sand, obtained by soaking in 5 vol% sodium hypochlorite solution for 24 h to remove surface organic residues, acid washing with dilute nitric acid at pH 2–3 for 5 min to dissolve surface-adsorbed heavy metals, rinsing with deionized water to neutrality, and drying at 40°C.

[0019] Furthermore, in the aforementioned component B, the microcapsule encapsulation system is an LDH intercalation encapsulation system, where LDH is a magnesium-aluminum layered double hydroxide. Interlayer anions for , Or amino acid anions; the LDH is intercalated and coated with the repair agent by co-precipitation or ion exchange, and the repair agent includes seawater-acclimated alkalophilic Bacillus dormant spores and oyster shell acid-hydrolyzed calcium ions. The concentration is 0.1–0.5 M.

[0020] Furthermore, the LDH particles described above have a particle size of 100–500 nm and an interlayer spacing of 1.5–2.5 nm. They remain stable in concrete pore fluid environments with a pH > 11.5, and dissolve and release the repair agent in cracks with seawater infiltration at a pH < 9.5. Simultaneously, they adsorb seawater through ion exchange. .

[0021] Preferably, the microcapsule encapsulation system is an LDH intercalation encapsulation system with a particle size of 200-300 nm and an interlayer spacing of 1.8-2.2 nm.

[0022] Preferably, the concentration of calcium ions from the acid hydrolysis of oyster shells is 0.2–0.4 M.

[0023] Furthermore, in the above-mentioned component B, the silane coupling agent is one or more of the functional group-containing silane coupling agents with a molecular weight of 200-300 and a viscosity of ≤10 mPa·s at 25°C.

[0024] Preferably, the silane coupling agent is at least one of γ-glycidoxypropyltrimethoxysilane / γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, and γ-mercaptopropyltrimethoxysilane.

[0025] Furthermore, in the above-mentioned component B, the accelerator is one or more of the tertiary amine or quaternary ammonium salt accelerators with a molecular weight of 150-300 and a viscosity of ≤100 mPa·s at 25°C.

[0026] Preferably, the aforementioned accelerator is at least one of 2,4,6-tris(dimethylaminomethyl)phenol, triethanolamine, benzyldimethylamine, 2-ethyl-4-methylimidazol, or DMP-30 tricresyl salt.

[0027] Furthermore, the aforementioned stress buffer coating is an epoxy glass flake coating, wherein the weight ratio of glass flakes in the epoxy glass flake coating is 30% to 40%.

[0028] Furthermore, the aforementioned ultra-weather-resistant protective coating is a polyaspartic acid ester polyurea.

[0029] A method for applying a repair coating to the concrete surface of a ship lock in a seawater immersion environment, comprising the following steps:

[0030] S1. Base surface diagnosis and cleaning: The concrete surface of the lock is inspected, and high-pressure fresh water jet is used to remove marine organisms, salt and aging layer, and then it is roughened by grinding.

[0031] S2. Construction of negative pressure microenvironment: A transparent negative pressure cover is set on the surface of the area to be repaired. The edge of the cover is set with a double-layer flexible sealing skirt. With the help of sealant, the tiny gap between the skirt and the concrete surface is filled to form a continuous sealing layer, so that the cover fits the rough concrete surface and constructs an airtight process cavity.

[0032] S3. In-situ vacuum dehydration and resistance removal: Start the vacuum pump to extract the air pressure inside the enclosure to -0.08 MPa to -0.098 MPa, and maintain the pressure for 10 to 30 minutes to allow the liquid water in the shallow pores of the concrete to quickly vaporize and be discharged; at the same time, remove the air from the shallow pores of the concrete.

[0033] S4. Negative pressure primer introduction: While maintaining a high negative pressure in the cavity, the resin feeding valve is opened, and the pre-prepared penetrating anchoring primer is drawn into the negative pressure hood under the action of the external atmospheric pressure difference, and the concrete base surface to be repaired is evenly covered by the diversion device.

[0034] S5. Controlled ventilation and pressure penetration: After the penetrating anchoring base coating completely covers the base surface, turn off the vacuum source and open the ventilation valve in a controlled manner; introduce dry nitrogen or hot air to restore the pressure inside the cover to normal pressure or pressurize it to a slightly positive pressure state; at this time, the deep pores of the concrete still maintain negative pressure, and the pressure gradient is used to forcefully press the liquid penetrating anchoring base coating covering the surface into the depths of capillaries and microcracks to achieve active penetration;

[0035] S6. Multi-layer system construction: Remove the negative pressure cover, and after the penetrating anchoring base coating has cured, apply the stress buffer intermediate coating and the ultra-weather-resistant protective top coating in sequence to complete the repair.

[0036] Furthermore, in step S3 above, the infrared heating device installed inside the cover is simultaneously turned on to perform auxiliary dehydration operation, and the heating temperature is controlled at 50-70℃.

[0037] Furthermore, in step S5 above, the vent valve is opened in a controlled manner at a rate of 0.01 to 0.05 MPa / s.

[0038] Furthermore, in step S5 above, the hot air is dry air at 40–60°C.

[0039] Furthermore, in step S5 above, the pressure inside the shroud recovers to normal pressure or is pressurized to a slightly positive pressure state of 0.01 to 0.05 MPa within 30 to 120 seconds.

[0040] Furthermore, in step S5 above, the deep pores of the concrete still maintain a negative pressure of -0.06 to -0.09 MPa, forming a pressure gradient of 0.07 to 0.14 MPa.

[0041] Furthermore, in step S5 above, after the pressure inside the shroud returns to normal pressure, it is evacuated again to -0.05 MPa and then quickly repressurized; this process is repeated 2 to 3 times.

[0042] Due to the adoption of the technical solution described above, the present invention has the following advantages:

[0043] This invention relates to a repair coating for the concrete surface of ship locks in seawater immersion environments. Its penetrating and anchoring undercoat utilizes low-viscosity epoxy resin, which readily penetrates into the micron-sized pores of the concrete under negative pressure. An active diluent further reduces the viscosity of the mixture to below 200 mPa·s, ensuring the penetrating and anchoring undercoat exhibits water-like fluidity. A Mannich base-modified cashew phenol aldehyde amine curing agent guarantees rapid curing of the penetrating and anchoring undercoat in low-temperature and humid environments. A silane coupling agent establishes a chemical molecular bridge between the organic resin and inorganic concrete, forming covalent bonds with the hydroxyl groups on the concrete surface through hydrolysis, significantly improving wet adhesion. A layered double hydroxide (LDH) intercalation coating system introduces seawater-acclimated alkalophilic Bacillus dormant spores and oyster shell acid-hydrolyzed calcium ions, triggering dissolution and release when seawater seeps into the cracks, inducing the deposition of aragonite-type deposits. Achieving self-healing of cracks, while simultaneously adsorbing seawater through ion exchange. Nearshore biomass active aggregates serve as homogeneous crystal nuclei to promote biomineralization and crystallization, ensuring the environmental safety of leached components; the stress-buffered intermediate coating can shield chloride ions and buffer the deformation stress of the substrate, while the ultra-weather-resistant protective topcoat has excellent UV resistance and seawater erosion resistance.

[0044] The present invention relates to a construction method for a repair coating on the concrete surface of a ship lock in a seawater immersion environment. This method utilizes physical pressure difference to actively drive the repair material into the depths of microcracks in the concrete, achieving deep anchoring repair without completely drying the substrate, thus significantly improving the impermeability and durability of the ship lock structure. Attached Figure Description

[0045] Figure 1 This is a schematic flowchart of the construction method for the repair coating on the concrete surface of a ship lock in a seawater immersion environment according to the present invention. Detailed Implementation

[0046] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] A repair coating for the surface of ship lock concrete in a seawater immersion environment is provided on the surface of the ship lock concrete. It comprises, from the inside out, a penetrating anchoring undercoat, a stress-buffering intermediate coat, and an ultra-weather-resistant protective topcoat. The penetrating anchoring undercoat is a solvent-free, low-viscosity, high-surface-activity two-component epoxy-biomineralization composite system, composed of component A (resin end) and component B (curing-mineralization functional end), which guides crack self-repair through a dual mechanism of chemical anchoring and biomineralization. Component A and component B are mixed at a weight ratio of 10:4-6. The components are uniformly combined. By weight, component A includes the following raw materials: 60-85 parts of a compound system of hyperbranched modified epoxy resin and bisphenol F type epoxy resin; 15-30 parts of reactive diluent; 0.2-0.5 parts of wetting and leveling agent; and 0.1-0.3 parts of defoamer. By weight, component B includes the following raw materials: 35-60 parts of Mannich base-modified cashew phenol aldehyde amine curing agent; 5-15 parts of near-shore biomass active aggregate; 3-8 parts of microencapsulation system; 1-3 parts of silane coupling agent; and 0.5-2.0 parts of accelerator.

[0048] In the above-mentioned component A, the epoxy equivalent (EEW) of the hyperbranched modified epoxy resin is controlled at 165-175 g / eq, and the viscosity at 25°C is 800-1200 mPa·s; the epoxy equivalent of the bisphenol F type epoxy resin is 160-170 g / eq, and the viscosity at 25°C is 2000-4000 mPa·s; the reactive diluent is one or a mixture of C12-C14 alkyl glycidyl ether (AGE) and 1,4-butanediol diglycidyl ether (BDGE); the wetting and leveling agent is polyether-modified polydimethylsiloxane (BYK-333), which reduces the surface tension of the system to below 25 mN / m; and the defoamer is a defoaming polymer solution (BYK-066N).

[0049] In the above-mentioned component B, the amine value of the Mannich base-modified cashew phenol aldehyde amine curing agent is 300-500 mgKOH / g, the viscosity at 25℃ is 1000-3000 mPa·s, and the active hydrogen equivalent is 95-110.

[0050] In component B above, the microcapsule encapsulation system is a layered double hydroxide (LDH) intercalation encapsulation system. The LDH carrier is prepared as magnesium-aluminum layered double hydroxide (MgAl-LDH) using a co-precipitation method, controlling the Mg / Al molar ratio to be 3:1. Through hydrothermal crystallization treatment, a hexagonal layered structure with uniform particle size (200–300 nm) and high crystallinity is obtained. The layers are positively charged, and the main anions between the layers are pre-positioned as... (nitrate); the biological nucleus is selected from dormant spores of Bacillus pseudofirmus, which has been domesticated in the seawater environment. This strain is tolerant to high alkali (pH>10) and high salt and can survive for a long time inside concrete; the calcium source is organic calcium ions prepared by acid hydrolysis of oyster shells.

[0051] In the above-mentioned component B, the near-shore biomass active aggregate is the collected waste oyster shells, which are washed, crushed, soaked in 5 vol% sodium hypochlorite for 24 hours to remove the organic film, and then rapidly acid-washed with dilute nitric acid with a pH of 3 for 5 minutes to remove surface heavy metals.

[0052] In the above-mentioned component B, the silane coupling agent is a 1:1 mixture of KH-560 (containing epoxy group) and KH-550 (containing amino group); KH-560 reacts with the resin of component A, and KH-550 works synergistically with the curing agent of component B.

[0053] The aforementioned stress buffer coating is an epoxy glass flake coating, wherein the weight ratio of glass flakes in the epoxy glass flake coating is 30% to 40%.

[0054] The aforementioned ultra-weather-resistant protective coating is a polyaspartic acid ester polyurea.

[0055] like Figure 1 As shown, a method for constructing a repair coating on the concrete surface of a ship lock in a seawater immersion environment includes the following steps:

[0056] S1. Base surface diagnosis and cleaning: The concrete surface of the lock is inspected, and high-pressure fresh water jet is used to remove marine organisms, salt and aging layer, and then it is roughened by grinding.

[0057] S2. Construction of negative pressure microenvironment: A transparent negative pressure cover is set on the surface of the area to be repaired. The edge of the cover is set with a double-layer flexible sealing skirt. With the help of sealant, the tiny gap between the skirt and the concrete surface is filled to form a continuous sealing layer, so that the cover fits the rough concrete surface and constructs an airtight process cavity.

[0058] S3. In-situ vacuum dehydration and resistance removal: Start the vacuum pump to extract the air pressure inside the enclosure to -0.08 MPa to -0.098 MPa and maintain the pressure for 10 to 30 minutes to allow the liquid water in the shallow pores of the concrete to quickly vaporize and be discharged; at the same time, extract the air from the shallow pores of the concrete; simultaneously turn on the infrared heating device installed inside the enclosure to perform auxiliary dehydration operation, and control the heating temperature at 50 to 70℃.

[0059] S4. Negative pressure primer introduction: While maintaining a high negative pressure in the cavity, the resin feeding valve is opened, and the pre-prepared penetrating anchoring primer is drawn into the negative pressure hood under the action of the external atmospheric pressure difference, and the concrete base surface to be repaired is evenly covered by the diversion device.

[0060] S5. Controlled Ventilation and Repressurization: After the penetrating anchoring base coating completely covers the substrate, turn off the vacuum source and open the ventilation valve in a controlled manner at a rate of 0.01–0.05 MPa / s; introduce dry nitrogen or hot air at 40–60°C to restore the pressure inside the enclosure to normal pressure or pressurize it to a slightly positive pressure state of 0.01–0.05 MPa within 30–120 seconds; at this time, the deep pores of the concrete still maintain a negative pressure of -0.06–-0.09 MPa, forming a pressure gradient of 0.07–0.14 MPa, which strongly presses the liquid penetrating anchoring base coating covering the surface into the capillaries and microcracks, achieving active penetration; use a pulsed circulation operation, that is, after the pressure inside the enclosure returns to normal pressure, evacuate again to -0.05 MPa and quickly repressurize; repeat this process 2–3 times;

[0061] S6. Multi-layer system construction: Remove the negative pressure cover, and after the penetrating anchoring base coating has cured, apply the stress buffer intermediate coating and the ultra-weather-resistant protective top coating in sequence to complete the repair.

[0062] Example 1

[0063] Standard repair system (for general microcrack areas)

[0064] Application scenario: Shrinkage cracks with a width of 0.1 to 0.2 mm exist on the wall of a ship lock chamber, and the base surface is damp.

[0065] A repair coating for the concrete surface of a ship lock in a seawater immersion environment is applied to the concrete surface of the ship lock and includes a penetrating anchoring base coating, a stress buffer intermediate coating, and an ultra-weather-resistant protective top coating arranged sequentially from the inside out. The penetrating anchoring base coating is a two-component epoxy-biomineralization composite system, composed of component A and component B mixed in a weight ratio of 10:5. Component A, by mass, includes the following raw materials: 10 parts of hyperbranched modified epoxy resin; 65 parts of bisphenol F type epoxy resin (NPEF-170); 25 parts of reactive diluent: C12-14 alkyl glycidyl ether; 0.3 parts of wetting and leveling agent: BYK-333; 0.2 parts of defoamer: BYK-066N; and a viscosity index of 180 at 25℃ after mixing. mPa·s; By mass parts, component B includes the following raw materials: 50 parts of Mannich base modified cashew phenol aldehyde amine curing agent (amine value 450); 10 parts of near-shore biomass active aggregate: oyster shell powder with a particle size of 100μm; 5 parts of LDH-spore microcapsule system; 2 parts of silane coupling agent: KH-560 / 550; 1.0 part of accelerator: DMP-30.

[0066] The above-mentioned construction method for repairing the concrete surface of a ship lock in a seawater immersion environment includes the following steps:

[0067] S1. Base surface diagnosis and cleaning: Use high-pressure fresh water jet (2500 bar) to remove marine organisms (barnacles, oysters) and aged loose layers from the surface. Then use diamond grinding discs to lightly grind and roughen the area around the cracks to expose fresh aggregate cross sections. At this point, the base surface is in a saturated surface dry (SSD) state.

[0068] S2. Negative pressure microenvironment construction: Install a transparent polycarbonate negative pressure cover in the area to be repaired (50cm×50cm). The edge of the cover is pre-installed with a double-layer flexible closed-cell rubber sealing skirt, and a high thixotropic sealant is applied to the contact surface between the skirt and the concrete to ensure a perfect airtightness on the rough base surface.

[0069] S3. In-situ vacuum dehydration and resistance removal: Connect a rotary vane vacuum pump and start evacuation; the absolute pressure inside the enclosure drops to 20 kPa (i.e., -0.08 MPa gauge pressure) within 90 seconds, and this negative pressure state is maintained for 20 minutes; Principle explanation: According to the phase diagram of water, at a pressure of 20 kPa, the boiling point of water drops to about 60℃; with the infrared heating lamp integrated inside the enclosure, the irradiation temperature is 60℃, and the liquid water in the microcracks and capillaries is rapidly boiled and vaporized and extracted, eliminating the "water wedge" that hinders resin penetration; at the same time, the closed air in the pores is also extracted, eliminating air resistance;

[0070] S4. Negative pressure primer introduction: Maintain the vacuum pump operation and open the resin feed valve; the pre-mixed penetrating anchoring primer is instantly drawn into the hood under the pressure difference between the external atmospheric pressure (~101 kPa) and the negative pressure inside the hood (~20 kPa), and is evenly covered on the dried crack surface through the guide device.

[0071] S5, Pulse-pressure penetration: After the penetration anchoring base coating completely covers the substrate, turn off the vacuum pump and open the vent valve in a controlled manner; introduce 50℃ hot air;

[0072] Phase 1 (Recompression): The pressure is rapidly restored to normal at a rate of 0.05 MPa / s. At this time, the external atmospheric pressure acts like an invisible giant hand, forcefully pushing the resin into the depths of the emptied microcracks.

[0073] Phase 2 (Pulse): To further enhance the penetration depth, two negative pressure-re-pressure pulse cycles are performed (the pressure is reduced to -0.05 MPa and then quickly released). By utilizing the breathing effect, the resin is pushed into deeper secondary capillaries (<10 μm).

[0074] S6. Multi-layer system construction: Remove the negative pressure cover, wait for the penetrating anchoring base coating to cure at 10℃ for 4 hours (surface dry), then apply the epoxy glass flake intermediate coating with a dry film thickness of 200μm, and finally spray the polyaspartic acid ester top coating with a dry film thickness of 150μm to complete the repair.

[0075] Example 2

[0076] High-penetration repair system (targeting aging microporous areas)

[0077] Application scenario: In the aging lock parts, although there are no large cracks on the surface, there is extensive capillary porosity and microcracks (<0.05mm), which urgently require deep sealing reinforcement.

[0078] A repair coating for the concrete surface of a ship lock in a seawater immersion environment is applied to the concrete surface of the ship lock and includes a penetrating anchoring base coating, a stress buffer intermediate coating, and an ultra-weather-resistant protective top coating arranged sequentially from the inside out. The penetrating anchoring base coating is a two-component epoxy-biomineralization composite system, composed of component A and component B mixed in a weight ratio of 10:4. Component A, by mass, includes the following raw materials: 20 parts of hyperbranched modified epoxy resin; 50 parts of bisphenol F type epoxy resin; 30 parts of reactive diluent: 1,4-butanediol diglycidyl ether; 0.3 parts of wetting and leveling agent: BYK-333; 0.2 parts of defoamer: BYK-066N; the viscosity index after mixing is 120 at 25℃. mPa·s, with fluidity close to that of water; by mass, component B includes the following raw materials: 45 parts of Mannich base modified cashew phenol aldehyde amine curing agent; 5 parts of near-shore biomass active aggregate: coral sand powder with a particle size of 45μm; 3 parts of LDH-spore microcapsule system; 2 parts of silane coupling agent: KH-560; 1.5 parts of accelerator: DMP-30.

[0079] The difference between the above-described method for constructing a repair coating on the concrete surface of a ship lock in a seawater immersion environment and the method in Example 1 is as follows:

[0080] S3, Vacuum Dehydration Enhancement: The vacuum level is increased to -0.095 MPa (close to the ultimate vacuum), and the pressure holding time is extended to 30 minutes to ensure the evaporation of moisture in deep (>10mm) pores;

[0081] S5. Positive pressure assisted permeation: During the repressurization, the atmosphere is not directly vented, but a compressed nitrogen source of 0.2 MPa is connected, forming a total pressure difference ΔP = 0.2 - (-0.095) ≈ 0.3 MPa; the huge pressure gradient drives the ultra-low viscosity resin to achieve ultra-deep permeation through the porous media flow described by Darcy's law.

[0082] The remaining steps are the same as in Example 1.

[0083] Example 3

[0084] Reinforced Repair System (for impact and wear resistant areas)

[0085] Application scenarios: Lock wall areas with drastic water level fluctuations and frequent ship friction require coatings with high strength and crack resistance.

[0086] A repair coating for the concrete surface of a ship lock in a seawater immersion environment is applied to the concrete surface of the ship lock and includes a penetrating anchoring base coating, a stress buffer intermediate coating, and an ultra-weather-resistant protective top coating arranged sequentially from the inside out. The penetrating anchoring base coating is a two-component epoxy-biomineralization composite system, composed of component A and component B mixed in a weight ratio of 10:6. Component A, by mass, includes the following raw materials: 10 parts hyperbranched modified epoxy resin; 75 parts bisphenol F type epoxy resin; 15 parts reactive diluent: AGE; 0.3 parts wetting and leveling agent: BYK-333; 0.2 parts defoamer: BYK-066N; viscosity index after mixing: 400 at 25℃. mPa·s; By mass parts, component B includes the following raw materials: 60 parts of Mannich base modified cashew phenol aldehyde amine curing agent; 15 parts of near-shore biomass active aggregate: a mixed grade of oyster shell powder and scallop shell powder with a particle size of 45-150μm; 8 parts of LDH-spore microcapsule system; 2 parts of silane coupling agent: KH-550; 0.5 parts of accelerator: DMP-30.

[0087] The difference between the above-described method for constructing a repair coating on the concrete surface of a ship lock in a seawater immersion environment and the method in Example 1 is as follows:

[0088] S5. Retention and penetration: Due to the high viscosity of the resin, after repressurization, maintain a slight positive pressure of 0.05 MPa for 10 minutes to give the resin sufficient rheological relaxation time to fill wide cracks (>0.2 mm).

[0089] The remaining steps are the same as in Example 1.

[0090] To fully demonstrate the advantages of the present invention in terms of formulation and construction process of the repair coating for the concrete surface of a ship lock in a seawater immersion environment and its construction method, three highly representative comparative examples are provided.

[0091] Comparative Example 1

[0092] Traditional manual roller coating process (verifying the advantages of vacuum process)

[0093] The coating material uses the same material formulation as in Example 1.

[0094] Construction method: No negative pressure hood or vacuum dehydration process was used; the method adopted was to directly apply the resin manually using a short-nap roller on the same damp and low-temperature (10℃, SSD state) concrete substrate; relying on the resin's own gravity and capillary action to penetrate.

[0095] The subsequent application of the intermediate and top coats is the same as in Example 1.

[0096] Comparative Example 2

[0097] Microencapsulation-free / active aggregate-free system (validating the advantages of bio-self-repair and LDH)

[0098] Coating materials: Component A is the same as in Example 1. Component B contains 50 parts cashew nut shell curing agent, 15 parts ordinary quartz powder (inert filler), 2 parts silane, and 1 part accelerator. It does not contain LDH-spore microcapsules or biomass active aggregates.

[0099] Construction method: Same as in Example 1, using vacuum negative pressure process.

[0100] Comparative Example 3

[0101] Conventional polyamide curing system (verifying the advantages of wet curing)

[0102] Coating material: The resin is the same as component A in Example 1, but the curing agent is replaced with a commercially available low molecular weight polyamide curing agent (type 650). This curing agent does not contain cashew phenol structure and has not undergone Mannich modification. It is currently the most commonly used curing agent for land-based anti-corrosion coatings. The filler is the same as in Example 1, containing LDH and bio-aggregate.

[0103] Construction method: Same as in Example 1, using vacuum negative pressure process.

[0104] The measured average values ​​of the key performance indicators of Examples 1, 2, and 3 and Comparative Examples 1, 2, and 3 (5 parallel samples in each group) are shown in Table 1:

[0105] Table 1. Measured average values ​​of key performance indicators for each embodiment and comparative example.

[0106]

[0107] Table 1 shows that Example 1, using a vacuum-assisted process, achieved a resin penetration depth of 5.5 mm and a bond strength of 4.8 MPa, with failure occurring within the concrete matrix (indicating that the interfacial strength was greater than the concrete strength). In contrast, Comparative Example 1, using a conventional manual roller coating, had a penetration depth of only 0.4 mm (essentially floating on the surface), a bond strength of only 1.8 MPa, and exhibited typical interfacial delamination failure. In damp concrete, capillaries are occupied by pore water. According to the Young-Laplace equation, the smaller the pore size, the greater the capillary pressure. For micron-sized pores, the resin's gravity alone cannot overcome the resistance of the liquid within the pores and the back pressure (gas resistance) of the enclosed gas. In Comparative Example 1, the resin could not displace the water within the pores, resulting in a water film at the interface and the formation of a weak boundary layer. The vacuum dehydration step in the construction method of this invention utilizes the principle of phase change thermodynamics. Under a negative pressure of -0.08 MPa, the boiling point of pore water decreases, and it rapidly vaporizes and is discharged, completely eliminating the "water wedge". The subsequent repressurization process creates a pressure gradient of up to 0.14 MPa. According to the Hagen-Poiseuille equation, the flow rate of fluid in a porous medium is proportional to the pressure difference, allowing the highly active resin to be pressed into the deep layers of concrete like nails, forming tens of thousands of micro resin anchors, which physically and completely lock the coating and the substrate.

[0108] Comparing Example 1 and Comparative Example 2, it can be seen that Example 1 achieves a self-healing rate of 92% for cracks, while Comparative Example 2, which removes the active component, only reaches 15%. Regarding resistance to chloride ion penetration, Example 1's 180°C is significantly superior to Comparative Example 2's 650°C. Comparative Example 2 relies solely on the physical barrier of epoxy resin; once the coating ages and cracks, the protection fails. Example 1 utilizes LDH-spore microcapsules to construct a smart system of detection-response-repair.

[0109] Comparing Example 1 and Comparative Example 3, it can be seen that in a low-temperature and humid environment of 10°C, Comparative Example 3 (ordinary polyamide) performed extremely poorly, remaining sticky and incompletely cured after 48 hours, with a bonding strength of only 0.9 MPa. Example 1, on the other hand, surface-dryed within 5 hours, exhibiting excellent strength. Ordinary amine curing agents are hydrophilic; under low temperature and high humidity, the amine groups readily react with CO2 and moisture in the air to form carbamates, resulting in an oily and whitish surface, hindering the cross-linking reaction. The Mannich base-modified cashew phenol used in the coating of this invention has a significant autocatalytic effect on the epoxy ring-opening reaction in its phenolic hydroxyl groups, allowing for rapid reaction even at 0°C or lower temperatures; simultaneously, its long-chain alkyl groups provide a hydrophobic protective umbrella, repelling moisture interference; combined with the chemical bonding effect of the silane coupling agent, it ensures high-strength chemical adsorption even underwater or at humid interfaces.

[0110] Therefore, this invention, through an innovative in-situ vacuum dehydration and pulsed re-pressurization process, successfully introduces polymer repair materials into the deep layers (>5mm) of damp concrete, transforming the repair interface from a two-dimensional plane to a three-dimensional structure, fundamentally solving the persistent problem of traditional coatings easily peeling off. The LDH-spore microcapsule system used in the coating of this invention endows the coating with the ability to sense chloride ion invasion and initiate biomineralization repair. It achieves a self-healing rate of over 92% for microcracks as narrow as 0.15mm, significantly extending the maintenance cycle of the structure.

[0111] The present invention provides a repair coating for the concrete surface of ship locks in seawater immersion environments and its construction method, which significantly improves the durability of concrete structures in water conservancy and water transport projects, especially coastal ship locks, wharves and cross-sea bridges, and has significant engineering application value and socio-economic benefits.

[0112] Although the present invention has been specifically shown and described in conjunction with preferred embodiments, there are many methods and approaches to implement this technical solution. The above description is only a preferred embodiment of the present invention. It should be noted that any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art without departing from the principle of the present invention should be included within the protection scope of the present invention.

Claims

1. A repair coating for the concrete surface of a ship lock in a seawater immersion environment, characterized in that: It is applied to the concrete surface of the lock and includes a penetrating anchoring base coating, a stress buffer intermediate coating, and an ultra-weather-resistant protective top coating, arranged sequentially from the inside out. The penetrating anchoring base coating is a two-component epoxy-biomineralization composite system, which is formed by uniformly mixing component A and component B in a weight ratio of 10:4 to 6. By weight, component A includes the following raw materials: 60 to 85 parts of a compound system of hyperbranched modified epoxy resin and bisphenol F type epoxy resin; 15 to 30 parts of reactive diluent; 0.2 to 0.5 parts of wetting and leveling agent; and 0.1 to 0.3 parts of defoamer. By weight, component B includes the following raw materials: 35 to 60 parts of Mannich base-modified cashew phenol aldehyde amine curing agent; 5 to 15 parts of nearshore biomass active aggregate; 3 to 8 parts of microencapsulation system; 1 to 3 parts of silane coupling agent; and 0.5 to 2.0 parts of accelerator. In its B component, the microcapsule encapsulation system is an LDH intercalation encapsulation system, where LDH is a magnesium-aluminum layered double hydroxide. Interlayer anions for , Or amino acid anions; the LDH is intercalated and coated with the repair agent by co-precipitation or ion exchange, and the repair agent includes seawater-acclimated alkalophilic Bacillus dormant spores and oyster shell acid-hydrolyzed calcium ions. The concentration is 0.1–0.5 M.

2. The repair coating for the concrete surface of a ship lock in a seawater immersion environment according to claim 1, characterized in that: It also includes one or more of the following features: (1) In component A, the epoxy equivalent of the hyperbranched modified epoxy resin is controlled at 165-175 g / eq, and the viscosity at 25℃ is 800-1200 mPa·s. (2) In component A, the epoxy equivalent of bisphenol F type epoxy resin is 160-170 g / eq, and the viscosity at 25℃ is 2000-4000 mPa·s; (3) In component A, the active diluent is one or more of C12-C14 alkyl glycidyl ether and 1,4-butanediol diglycidyl ether; (4) In component B, the amine value of the Mannich base-modified cashew phenol aldehyde amine curing agent is 300-500 mgKOH / g, the viscosity at 25℃ is 1000-3000 mPa·s, and the active hydrogen equivalent is 95-110. (5) In component B, the near-shore biomass active aggregate is at least one of oyster shell powder, scallop shell powder or coral sand; (6) In component B, the silane coupling agent is one or more of the functional group-containing silane coupling agents with a molecular weight of 200-300 and a viscosity of ≤10 mPa·s at 25℃. (7) In component B, the accelerator is one or more of the tertiary amine or quaternary ammonium salt accelerators with a molecular weight of 150 to 300 and a viscosity of ≤100 mPa·s at 25°C.

3. The repair coating for the concrete surface of a ship lock in a seawater immersion environment according to claim 1, characterized in that: The LDH particle size is 100–500 nm, and the interlayer spacing is 1.5–2.5 nm.

4. The repair coating for the concrete surface of a ship lock in a seawater immersion environment according to claim 3, characterized in that: The microcapsule encapsulation system is an LDH intercalation encapsulation system with a particle size of 200-300 nm and an interlayer spacing of 1.8-2.2 nm.

5. The repair coating for the concrete surface of a ship lock in a seawater immersion environment according to claim 1, characterized in that: The stress buffer coating is an epoxy glass flake coating, wherein the weight ratio of glass flakes in the epoxy glass flake coating is 30% to 40%.

6. The repair coating for the concrete surface of a ship lock in a seawater immersion environment according to claim 1, characterized in that: The ultra-weather-resistant protective coating is polyaspartic acid ester polyurea.

7. A method for constructing a repair coating for a ship lock concrete surface in a seawater immersion environment as described in any one of claims 1 to 6, characterized in that: It includes the following steps: S1. Base surface diagnosis and cleaning: The concrete surface of the lock is inspected, and high-pressure fresh water jet is used to remove marine organisms, salt and aging layer, and then it is roughened by grinding. S2. Construction of negative pressure microenvironment: A transparent negative pressure cover is set on the surface of the area to be repaired. The edge of the cover is set with a double-layer flexible sealing skirt. With the help of sealant, the tiny gap between the skirt and the concrete surface is filled to form a continuous sealing layer, so that the cover fits the rough concrete surface and constructs an airtight process cavity. S3. In-situ vacuum dehydration and resistance removal: Start the vacuum pump to extract the air pressure inside the enclosure to -0.08 MPa to -0.098 MPa, and maintain the pressure for 10 to 30 minutes to allow the liquid water in the shallow pores of the concrete to quickly vaporize and be discharged; at the same time, remove the air from the shallow pores of the concrete. S4. Negative pressure primer introduction: While maintaining a high negative pressure in the cavity, the resin feeding valve is opened, and the pre-prepared penetrating anchoring primer is drawn into the negative pressure hood under the action of the external atmospheric pressure difference, and the concrete base surface to be repaired is evenly covered by the diversion device. S5. Controlled ventilation and pressure penetration: After the penetrating anchoring base coating completely covers the base surface, turn off the vacuum source and open the ventilation valve in a controlled manner; introduce dry nitrogen or hot air to restore the pressure inside the cover to normal pressure or pressurize it to a slightly positive pressure state; at this time, the deep pores of the concrete still maintain negative pressure, and the pressure gradient is used to forcefully press the liquid penetrating anchoring base coating covering the surface into the depths of capillaries and microcracks to achieve active penetration; S6. Multi-layer system construction: Remove the negative pressure cover, and after the penetrating anchoring base coating has cured, apply the stress buffer intermediate coating and the ultra-weather-resistant protective top coating in sequence to complete the repair.

8. The construction method of the repair coating on the concrete surface of a ship lock in a seawater immersion environment according to claim 7, characterized in that: It also includes one or more of the following features: (1) In step S3, the infrared heating device installed inside the cover is turned on simultaneously to perform auxiliary dehydration operation, and the heating temperature is controlled at 50-70℃. (2) In step S5, the hot air is dry air at 40-60°C; (3) In step S5, the vent valve is opened in a controlled manner at a rate of 0.01 to 0.05 MPa / s; (4) In step S5, the pressure inside the shroud recovers to normal pressure or is pressurized to a slightly positive pressure state of 0.01-0.05 MPa within 30-120 seconds; (5) In step S5, the deep pores of the concrete still maintain a negative pressure of -0.06 to -0.09 MPa, forming a pressure gradient of 0.07 to 0.14 MPa; (6) In step S5, after the pressure inside the shroud returns to normal pressure, the shroud is evacuated again to -0.05 MPa and then quickly repressurized; repeat this process 2 to 3 times.

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