Nuclear power plant structure concrete penetration repairing method

Abstract

The invention belongs to the technical field of nuclear power, and particularly relates to a nuclear power plant structure concrete permeation repairing method. According to the method, an effective permeation repair technology is provided for the concrete corrosion problem caused by chloride ion erosion, a set of complete technical process is provided from permeation repair material selection, spraying pre-test, construction to quality acceptance, and systematicness and normalization of repair work are ensured. Compared with a traditional concrete corrosion repairing method, the method is simple and clear in step and easy to operate, the construction difficulty and cost are reduced, the permeation corrosion repairing work becomes more efficient and feasible, and the method is suitable for concrete corrosion repairing of bridges, seaport facilities, roads, buildings and other infrastructures and also suitable for concrete corrosion repairing of the infrastructures such as the bridges, the seaport facilities, the roads and the buildings. The method can also be widely applied to other concrete structures needing long-term protection and maintenance, and has important popularization value in modern city construction and infrastructure maintenance.

Description

Technical Field

[0001] This disclosure belongs to the field of nuclear power technology, specifically relating to a method for repairing concrete seepage in nuclear power plant structures. Background Technology

[0002] In modern urban construction and infrastructure maintenance, concrete, as a widely used building material, has always been a focus of attention for engineers and researchers regarding its durability and long-term performance. Among related technologies, chloride ion corrosion is one of the main forms of concrete corrosion. When chloride ions penetrate the interior of concrete, they react chemically with the reinforcing steel, causing it to rust and subsequently leading to cracking, spalling, and a decline in the overall performance of the concrete structure. This corrosion phenomenon is particularly common in infrastructure such as bridges, harbor facilities, roads, and buildings, posing significant challenges to public safety and economic efficiency.

[0003] Traditional methods for repairing concrete corrosion are often limited to localized repairs, such as surface repairs using materials like epoxy resin and polymer mortar. However, these methods are ineffective against penetrating corrosion and cannot guarantee sufficient durability and long-term performance of the repaired concrete structure. Furthermore, traditional methods suffer from long construction periods, high costs, and difficulties in assessing repair effectiveness.

[0004] In view of the above, it is urgent to improve the quality of concrete corrosion repair, thereby extending the service life of infrastructure and improving public safety and economic benefits. Summary of the Invention

[0005] To overcome the problems existing in related technologies, a method for repairing concrete seepage in nuclear power plant structures is provided.

[0006] According to one aspect of the present disclosure, a method for repairing concrete seepage in nuclear power plant structures is provided, the method comprising:

[0007] Step 1: Select appropriate repair materials based on the corrosion state of the concrete to be repaired in the nuclear power plant.

[0008] Step 2: Select a suitable location at the nuclear power plant site to conduct a pre-spraying test. After the pre-spraying test is completed, randomly drill multiple core samples in the test area, test each core sample separately, and determine whether the test results meet the test judgment criteria.

[0009] Step 3: If the test results of the pre-spraying test meet the test judgment criteria, carry out formal repair on the concrete structure to be repaired;

[0010] Step 4: After the formal repair spraying is completed, inspect and accept the formally repaired area. If the inspection and acceptance is passed, the formal repair is completed. If the inspection and acceptance is not passed, repeat steps 3 and 4 until the inspection and acceptance is passed.

[0011] In one possible implementation, in step 1, if the concrete structure has minor cracks and is in the early stage of carbonation and chloride ion erosion, then silane-based penetrating materials are selected as the repair material; if the concrete has structural leakage, then cementitious penetrating materials are selected as the repair material; if the concrete has micro-cracks or seepage channels, then organic polymer-based penetrating materials are selected as the repair material.

[0012] The ratio of the coefficient of thermal expansion of the repair material to that of the concrete to be repaired is between 0.5 and 2.0, and the ratio of the elastic modulus of the repair material to that of the concrete to be repaired is between 0.5 and 2.0.

[0013] In one possible implementation, step 2 includes:

[0014] Step 21: Before the pre-spray test, the area connected to the reinforcing steel in the corroded concrete to be repaired is used as the test area, and the corrosion potential of the test area is measured using a steel corrosion detector.

[0015] Step 22, during the pre-test spraying process, the selected repair material is used to spray the test area;

[0016] Step 23: After the pre-spraying test is completed, multiple core samples are randomly drilled in the test area. For each core sample, the on-site corrosion potential, water absorption rate, and the depth of immersion of the repair material are tested. The test criteria include: the average water absorption rate of each core sample should not exceed 0.01 mm / min. 1 / 2 For concrete with a strength grade not greater than C45, the immersion depth should reach 3-4 mm; for concrete with a strength grade equal to or greater than C45, the immersion depth should reach 2-3 mm; the on-site corrosion potential should be greater than -200 mV.

[0017] In one possible implementation, the spraying operation for pre-test and formal repair includes: if the area to be sprayed is on a vertical surface, spraying from bottom to top, keeping the area saturated and overflowing for at least 5 seconds; if the area to be sprayed is on a top or bottom surface, keeping the area saturated and overflowing for at least 5 seconds; the spraying operation is carried out in 2-3 spraying operations, with an interval of at least 6 hours between each two spraying operations.

[0018] In one possible implementation, liquid repair materials are applied by spraying with a low-pressure pump using a fan-shaped nozzle or by spraying with a large-volume spray bottle; paste or emulsion repair materials are applied by brushing with a roller or a large brush.

[0019] In one possible implementation, the amount of repair material used in each spraying operation depends approximately on the degree of concrete corrosion, chloride ion content, and the environment in which the building is located.

[0020] In one possible implementation, if the width of the concrete corrosion crack does not exceed 0.2 mm, the chloride ion content does not exceed 0.1%, and the wind speed in the environment where the concrete to be repaired is located does not exceed 8 m / s, then the amount of repair material used is 200 g / m³. 2 -250 g / m 2 If the width of the corrosion crack in the concrete to be repaired exceeds 0.2 mm, or the chloride ion content exceeds 0.1%, or the wind speed in the environment where the concrete to be repaired is located exceeds 8 m / s, then the dosage of the repair material is 300 g / m³. 2 -400g / m 2 .

[0021] In one possible implementation, step 3 includes:

[0022] Step 31: Before construction, the surface of the area to be repaired is cleaned by sandblasting, water cleaning, grinding and chemical cleaning to remove exogenous substances that inhibit penetration.

[0023] Step 32: Apply the selected repair material to the cleaned area to be repaired using a repair spraying operation.

[0024] In one possible implementation, step 4 includes: dividing the formally repaired area into multiple sub-areas according to a preset area, with each sub-area as a quality acceptance batch; taking two test points in each sub-area for hydrophobicity testing and on-site corrosion potential testing; when the hydrophobicity test result or on-site corrosion potential test result of any acceptance batch meets the following conditions, the inspection and acceptance are passed; when the hydrophobicity test result or on-site corrosion potential test result of any acceptance batch does not meet the following conditions, repeating steps 3 and 4 until the hydrophobicity test result and on-site corrosion potential test result of any acceptance batch meet the following conditions:

[0025] The hydrophobicity test liquid level was reduced by more than 50% compared to the control group; the on-site corrosion potential was greater than -200mV;

[0026] The hydrophobicity test refers to the on-site hydrophobicity test conducted 14 days after construction. Two points were selected on the concrete surface that were not treated with the repair material and two points were selected on the concrete surface that were treated with the repair material. The tests were carried out simultaneously for comparison.

[0027] The on-site corrosion potential test means that the corrosion resistance test is carried out on-site 150 days after the completion of construction. The corrosion potential of the two test points is measured again using a steel rust detector and compared with the results before the test.

[0028] The beneficial effects of this disclosure are as follows: This disclosure provides an effective penetrating repair technology for concrete corrosion caused by chloride ion attack. It offers a complete technical process, from the selection of penetrating repair materials and pre-spray testing to construction and quality acceptance, ensuring the systematic and standardized nature of the repair work. Compared with traditional concrete corrosion repair methods, the method of this disclosure is simple and clear, easy to operate, and reduces construction difficulty and cost. This makes the repair of penetrating corrosion more efficient and feasible. This method is not only suitable for the repair of concrete corrosion in infrastructure such as bridges, harbor facilities, roads, and buildings, but can also be widely applied to other concrete structures requiring long-term protection and maintenance, and has significant promotional value in modern urban construction and infrastructure maintenance. Attached Figure Description

[0029] Figure 1 This is a flowchart illustrating a method for repairing concrete seepage in nuclear power plant structures, as shown in an embodiment of this disclosure.

[0030] Figure 2 This is a schematic diagram of an on-site test of the steel reinforcement corrosion potential test group at a nuclear power plant.

[0031] Figure 3 A schematic diagram of a high-altitude painting operation at a nuclear power plant.

[0032] Figure 4 A schematic diagram showing the on-site recording of a hydrophobicity test group at a nuclear power plant.

[0033] Figure 5 A schematic diagram of the field records for the control group of a hydrophobicity test at a nuclear power plant.

[0034] Figure 6 This is a schematic diagram of the hydrophobicity test results of a nuclear power plant. Detailed Implementation

[0035] The present disclosure will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0036] Unless otherwise defined, the technical and scientific terms used in this disclosure have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains; the terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure; the term "comprising" and any variations thereof in this disclosure are intended to cover non-exclusive inclusion. Clearly, the embodiments described in this disclosure are only a part of the embodiments of this disclosure, and not all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of this disclosure without inventive effort are within the scope of protection of this disclosure.

[0037] In this disclosure, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this disclosure. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0038] Figure 1 This is a flowchart illustrating a method for repairing concrete seepage in nuclear power plant structures, as shown in the embodiments of this disclosure. Figure 1 As shown, the method includes:

[0039] Step 1: Select appropriate repair materials based on the state of concrete corrosion at the nuclear power plant site.

[0040] If a concrete structure has minor cracks and is in the early stages of carbonation and chloride ion corrosion, silane-based penetrating materials are chosen as the repair material. Silane-based penetrating materials are suitable for various complex structures (including the bottom of bridges). They exhibit good corrosion resistance and lifespan extension effects on concrete components in chloride environments. The application process for silane-based penetrating materials is simple, with a short penetration time, typically 1–2 hours, followed by natural drying and curing.

[0041] If structural leakage occurs in concrete, cementitious penetrating materials are chosen as the repair material. These materials include nano-silica sol and ultrafine cement, and are suitable for both horizontal and vertical structural repairs. The application time for this type of material is generally no less than 4 hours, and the curing period is typically 1–3 days. It possesses certain structural reinforcement and leakage sealing properties.

[0042] If micro-cracks or water seepage channels appear in concrete, organic polymer-based penetrating materials are chosen as the repair material. These materials include low-viscosity epoxy resins and polyurethane grouts, suitable for both floor and facade structures. The curing time for organic polymer-based penetrating materials is generally 0.5–6 hours, with an application time of 2–4 hours. Combined with several hours of curing, the structure's functionality can be quickly restored, making it suitable for repairing time-sensitive critical areas.

[0043] The properties of the repair material should match the original properties of the concrete to be repaired. For example, the ratio of the coefficient of thermal expansion of the repair material to that of the concrete to be repaired should be between 0.5 and 2.0, and the ratio of the elastic modulus of the repair material to that of the concrete to be repaired should be between 0.5 and 2.0. At the same time, the repair material should also meet the requirements of the service environment and construction conditions.

[0044] Step 2: Select a suitable location at the nuclear power plant site to conduct a pre-conducting spraying test, including:

[0045] Step 21: Before the pre-spray test, the area connected to the reinforcing steel in the corroded concrete to be repaired is designated as the test area. (See [link]). Figure 2 The corrosion potential of the test area was measured using a steel corrosion detector.

[0046] Step 22, during the pre-test spraying process, the selected repair material is used to spray the test area.

[0047] Step 23: After the pre-spraying test is completed, multiple core samples are randomly drilled in the test area. For each core sample, the on-site corrosion potential, water absorption rate, and the immersion depth of the repair material are tested. When the test results meet the following criteria, formal repair is carried out on the concrete structure to be repaired.

[0048] The average water absorption rate should not exceed 0.01 mm / min. 1 / 2 For concrete with a strength grade not exceeding C45, the immersion depth should reach 3-4 mm; for concrete with a strength grade equal to or greater than C45, the immersion depth should reach 2-3 mm; the on-site corrosion potential should be greater than -200 mV. If the test results do not meet the judgment criteria, a new repair material can be selected for a pre-spray test until the test results meet the judgment criteria.

[0049] Step 3, see Figure 3 The selected repair materials are then sprayed onto the area to be repaired, including:

[0050] Step 31: Before construction, the surface of the area to be repaired is cleaned by methods such as sandblasting, water-cooled sand removal, grinding and chemical cleaning to remove all dirt, dust, weathering, mold, oil stains, asphalt, laitance, paint, coatings, hardeners and other exogenous substances that may inhibit penetration.

[0051] Step 32: Apply the selected repair material to the cleaned area to be repaired using a repair spraying operation.

[0052] Step 4: After the repair spraying operation, inspect and accept the area where the repair spraying operation was carried out.

[0053] The area to be repaired and sprayed will be determined according to a predetermined area (e.g., 100m²). 2 The area is divided into multiple sub-regions, with each sub-region constituting a quality acceptance batch. See [link / reference]. Figure 2 , Figures 4 to 6 Two test points were selected in each sub-region to conduct hydrophobicity tests and in-situ corrosion potential tests. If the hydrophobicity test results or in-situ corrosion potential test results of any acceptance batch do not meet the following conditions, steps 3 and 4 were repeated until the hydrophobicity test results and in-situ corrosion potential test results of any acceptance batch met the following conditions:

[0054] The hydrophobicity test liquid level was reduced by more than 50% compared to the control group; the on-site corrosion potential was greater than -200mV. The hydrophobicity test was conducted on-site 14 days after construction. Two points were selected on the concrete surface that had not been treated with the repair material (control group) and two points on the concrete surface that had been treated with the repair material (test group), and the tests were carried out simultaneously for comparison.

[0055] The on-site corrosion potential test means that the corrosion resistance test is carried out on-site 150 days after the completion of construction. The corrosion potential of the two test points is measured again using a steel rust detector and compared with the results before the test.

[0056] In one possible implementation, the spraying operation includes: if the area to be sprayed is on a vertical surface, spraying from bottom to top, maintaining the area in a saturated overflow state for at least 5 seconds; if the area to be sprayed is on a top or bottom surface, maintaining the area in a saturated overflow state for at least 5 seconds. Two to three spraying operations can be performed, with an interval of at least 6 hours between each two spraying operations.

[0057] Liquid repair materials can be applied using a low-pressure pump with a fan-shaped nozzle or a large-volume spray bottle. Paste or emulsion-like repair materials can be applied using a roller or a large brush. The amount of repair material used in each spraying operation depends approximately on the degree of concrete corrosion, chloride ion content, and the environment in which the building is located.

[0058] For example, if the width of the concrete corrosion crack does not exceed 0.2 mm and the chloride ion content does not exceed 0.1%, then the amount of repair material used is 200 g / m². 2 -250 g / m 2 If the width of the corrosion crack in the concrete to be repaired exceeds 0.2 mm, or the chloride ion content exceeds 0.1%, or the wind speed in the environment where the concrete to be repaired is located exceeds 8 m / s, then the dosage of the repair material is 300 g / m³. 2 -400g / m 2 This allows for the preparation of an appropriate amount of repair materials based on the actual corrosion state of the concrete to be repaired, avoiding insufficient material preparation or waste.

[0059] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for repairing concrete seepage in nuclear power plant structures, characterized in that, The method includes: Step 1: Select appropriate repair materials based on the corrosion state of the concrete to be repaired in the nuclear power plant. Step 2: Select a suitable location at the nuclear power plant site to conduct a pre-spraying test. After the pre-spraying test is completed, randomly drill multiple core samples in the test area, test each core sample separately, and determine whether the test results meet the test judgment criteria. Step 3: If the test results of the pre-spraying test meet the test judgment criteria, carry out formal repair on the concrete structure to be repaired; Step 4: After the formal repair spraying is completed, inspect and accept the formally repaired area. If the inspection and acceptance is passed, the formal repair is completed. If the inspection and acceptance is not passed, repeat steps 3 and 4 until the inspection and acceptance is passed.

2. The method according to claim 1, characterized in that, In step 1, if the concrete structure has minor cracks and is in the early stage of carbonation and chloride ion erosion, then silane-based penetrating materials are selected as the repair materials; if the concrete has structural leakage, then cementitious penetrating materials are selected as the repair materials. If micro-cracks or water seepage channels appear in the concrete, organic polymer-based penetrating materials should be selected as the repair materials. The ratio of the coefficient of thermal expansion of the repair material to that of the concrete to be repaired is between 0.5 and 2.0, and the ratio of the elastic modulus of the repair material to that of the concrete to be repaired is between 0.5 and 2.

0.

3. The method according to claim 1, characterized in that, Step 2 includes: Step 21: Before the pre-spray test, the area connected to the reinforcing steel in the corroded concrete to be repaired is used as the test area, and the corrosion potential of the test area is measured using a steel corrosion detector. Step 22, during the pre-test spraying process, the selected repair material is used to spray the test area; Step 23: After the pre-spraying test is completed, multiple core samples are randomly drilled in the test area. For each core sample, the on-site corrosion potential, water absorption rate, and the depth of immersion of the repair material are tested. The test criteria include: the average water absorption rate of each core sample should not exceed 0.01 mm / min. 1 / 2 For concrete with a strength grade not greater than C45, the immersion depth should reach 3-4 mm; for concrete with a strength grade equal to or greater than C45, the immersion depth should reach 2-3 mm; the on-site corrosion potential should be greater than -200 mV.

4. The method according to claim 1, characterized in that, The spraying operation for pre-test and formal repair includes: if the area to be sprayed is on a vertical surface, spray from bottom to top, keeping the area saturated and overflowing for at least 5 seconds; if the area to be sprayed is on the top or bottom surface, keep the area saturated and overflowing for at least 5 seconds; the spraying operation is carried out in 2-3 spraying operations, with an interval of at least 6 hours between each two spraying operations.

5. The method according to claim 4, characterized in that, Liquid repair materials are applied by spraying with a low-pressure pump using a fan-shaped nozzle or by spraying with a large-volume spray bottle; paste or emulsion repair materials are applied by brushing with a roller or a large brush.

6. The method according to claim 4, characterized in that, The amount of repair material used in each spraying operation depends on the degree of concrete corrosion, chloride ion content, and the environment in which the building is located.

7. The method according to claim 6, characterized in that, If the width of the concrete corrosion crack does not exceed 0.2 mm, the chloride ion content does not exceed 0.1%, and the wind speed in the environment where the concrete to be repaired is located does not exceed 8 m / s, then the dosage of the repair material is 200 g / m³. 2 -250 g / m 2 If the width of the corrosion crack in the concrete to be repaired exceeds 0.2 mm, or the chloride ion content exceeds 0.1%, or the wind speed in the environment where the concrete to be repaired is located exceeds 8 m / s, then the dosage of the repair material is 300 g / m³. 2 -400g / m 2 .

8. The method according to claim 1, characterized in that, Step 3 includes: Step 31: Before construction, the surface of the area to be repaired is cleaned by sandblasting, water cleaning, grinding and chemical cleaning to remove exogenous substances that inhibit penetration. Step 32: Apply the selected repair material to the cleaned area to be repaired using a repair spraying operation.

9. The method according to claim 1, characterized in that, Step 4 includes: dividing the formally repaired area into multiple sub-areas according to a preset area, with each sub-area serving as a quality acceptance batch. Two test points are selected in each sub-area for hydrophobicity testing and on-site corrosion potential testing. If the hydrophobicity test result or on-site corrosion potential test result of any acceptance batch meets the following conditions, the inspection and acceptance are passed. If the hydrophobicity test result or on-site corrosion potential test result of any acceptance batch does not meet the following conditions, steps 3 and 4 are repeated until the hydrophobicity test result and on-site corrosion potential test result of any acceptance batch meet the following conditions: The hydrophobicity test liquid level was reduced by more than 50% compared to the control group; the on-site corrosion potential was greater than -200mV; The hydrophobicity test refers to the on-site hydrophobicity test conducted 14 days after construction. Two points were selected on the concrete surface that were not treated with the repair material and two points were selected on the concrete surface that were treated with the repair material. The tests were carried out simultaneously for comparison. The on-site corrosion potential test means that the corrosion resistance test is carried out on-site 150 days after the completion of construction. The corrosion potential of the two test points is measured again using a steel rust detector and compared with the results before the test.

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