Method for repairing reinforcing steel bars in marine concrete on site by using corrosion-resistant composition

Abstract

The invention relates to the technical field of marine concrete reinforcing steel bar repairing, and discloses a method for repairing reinforcing steel bars in marine concrete on site by using a corrosion-resistant composition, which comprises the following steps: (1) delimiting a repairing area, and positioning the reinforcing steel bars in the repairing area by using a reinforcing steel bar position determinator; measuring the corrosion rate and the corrosion current by adopting a corrosion rate tester, and determining a brushed surface and a pouring point; (2) pretreating the outer surface of the marine concrete on a brushed surface and a pouring point; (3) mixing the anti-rust composition with water to prepare an anti-rust composition aqueous solution; the pretreated brushing surface is brushed with the aqueous solution of the anti-rust composition; (4) each time of painting is carried out after the previous painting surface is dried at intervals of a period of time, and meanwhile, pouring is carried out at the pre-treated pouring point; and (5) post-treatment is conducted on the repaired area obtained after painting and pouring, and it is confirmed that repairing is completed. The anti-rust paint has a good anti-rust effect and high protection durability.

Description

Technical Field

[0001] The invention relates to the technical field of marine concrete steel bar repair, and in particular to a method for on-site repairing steel bars in marine concrete by using a rust-proofing composition. Background Art

[0002] At present, reinforced concrete has durability problems. Especially under the harsh marine environment and various corrosive media, the service life of reinforced concrete is shortened and cannot meet the design requirements. More and more development funds have to be occupied by repair, maintenance and even demolition and reconstruction projects, which has a serious impact on the sustainable development of the social economy.

[0003] Steel bar corrosion caused by chloride salts is the main factor affecting the durability of concrete structures. The main corrosion protection measures for reinforced concrete include the concrete surface coating method, which can form a protective layer on the surface of the steel bar to prevent the corrosive medium in the atmosphere from entering the interior of the concrete, thereby slowing down the corrosion rate of the steel bar. For example, Chinese patent CN112851195 A discloses an additive for inhibiting stray current corrosion of reinforced concrete, including a rust inhibitor and a hydrophobic component, wherein the amount of the rust inhibitor is between 0.1% and 5% of the cement mass, and the amount of the hydrophobic component is 0.01% to 2% of the cement mass. The hydrophobic component is directly added to the concrete or treated with the reinforced concrete by dipping or external coating. When the total amount of brushing is insufficient, the concentration of nitrite ions is insufficient, the penetration is insufficient, and macro-cells are generated on the surface of the steel bar, causing macro-cell corrosion. When the total amount of brushing is too large, the excess rust inhibitor cannot effectively penetrate into the interior of the concrete, but stays on the surface of the concrete to form a thicker coating; at the same time, a single coating also has the defect of slow penetration. Summary of the invention

[0004] In order to overcome the problems in the prior art that when the total amount of coating is insufficient, the concentration of nitrite ions is insufficient, the penetration is insufficient, macro-cells are generated on the surface of the steel bars, and macro-cell corrosion occurs; when the total amount of coating is too large, the excess rust inhibitor cannot effectively penetrate into the concrete, but stays on the surface of the concrete to form a thicker coating; and at the same time, a single coating also has the above-mentioned shortcomings of slow penetration. A method for on-site repair of steel bars in marine concrete using a rust-inhibiting composition is provided, which has good rust-inhibiting effect and high protection durability; under the combined action of coating and pressure perfusion, the concentration of each point can be improved as a whole, making up for the shortcomings of slow penetration of a single coating and uneven penetration of a single pressure perfusion, and the final free nitrite ion content is greatly improved And other advantages.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A method for repairing steel bars in marine concrete on site using a rust-inhibiting composition comprises the following steps: (1) Delineate the repair area and use a steel bar position measuring instrument to locate the steel bars in the repair area; measure their corrosion rate and corrosion current, and measure their potential to determine the coating surface and injection point; (2) Pre-treat the outer surface of marine concrete at the painting surface and pouring point; (3) Mix the rust-inhibiting composition with water to prepare an aqueous solution of the rust-inhibiting composition; apply the aqueous solution of the rust-inhibiting composition to the pre-treated surface; when applying, moisten the polished surface with a saturated nitrite solution to form a water film on the polished surface, cover the frosted surface with a water-absorbing material that has absorbed enough nitrite aqueous solution, then cover the water-absorbing material with a waterproof material, and fix the edges of the waterproof material on the surface of the reinforced concrete structure with a seal; finally, press a heavy object on the waterproof material to compress the thickness of the water-absorbing material by more than 1 / 3, and keep it for 2 to 3 weeks; (4) Each time you apply paint, wait for a while until the surface is dry before applying it again. The total amount of paint applied is 1.75~2.63 At the same time, perfusion is performed at the pretreated perfusion points, the perfusion pressure is 0.1-0.2Mpa, and the perfusion volume of each perfusion point is 50-150ml; (5) Perform post-treatment on the repaired area after painting and pouring to confirm that the repair is complete.

[0006] Preferably, in step (2), the pretreatment is to repair, clean and sand the outer surface of the marine concrete.

[0007] Preferably, in step (3), the pouring is performed using a low-pressure pourer, specifically: the base of the low-pressure pourer is fixed at the pouring point, the low-pressure pourer draws a pouring amount of the rust-inhibiting composition aqueous solution, the low-pressure pourer is connected to the base, the rust-inhibiting composition aqueous solution is poured into the reinforced concrete, and the base is removed after the pouring is completed.

[0008] Preferably, in step (3), the low-pressure infusion device comprises a base with a liquid outlet, a liquid outlet pipe and a cylinder having one end connected to the liquid outlet pipe, and the base and the liquid outlet pipe are detachably connected.

[0009] Preferably, in step (3), each application is performed after the previously applied surface has dried for 3 to 5 hours.

[0010] Preferably, the rust-inhibiting composition comprises an anodic rust-inhibiting component A and a cathodic rust-inhibiting component B, wherein the anodic rust-inhibiting component A is sodium nitrite and the cathodic rust-inhibiting component B is benzotriazole, and the weight ratio of the two is 1 to 9:3.

[0011] Preferably, the Cl- content in the marine concrete is 1 to 4 The water-cement ratio of the marine concrete is in the range of 0.3-0.5, the sand ratio is 38-45%, the slump is 15-17cm, and the air content is 3-5%.

[0012] Preferably, the amount of the rust-inhibiting composition added is: the molar ratio of NO2- in the rust-inhibiting composition to Cl- in the marine concrete is 0.8~1.2:1.

[0013] Preferably, the cement in the marine concrete is silicate cement, with an addition amount of 280-320 , river sand with fineness modulus of 2.6~2.8, added in an amount of 750~770 , the particle size is 10~20mm, the addition amount is 1000~1100 .

[0014] Preferably, the steel bars in the marine concrete contain 0.2-0.3% C, 0.3-0.4% Si, 1.3-1.4% Mn, 0.2-0.3% P, 0.02-0.03% S, 0.08-0.09% Cr, 0.04-0.05% Ni, and 0.01-0.02Mo.

[0015] The beneficial effects of the present invention are as follows: (1) The corrosion-resistant reinforced concrete structure of the present invention has a good rust-proof effect and a high degree of protection durability; (2) Under the combined action of the coating and pressure perfusion of the present invention, the concentration of each point can be improved as a whole, making up for the shortcomings of slow penetration of a single coating and uneven penetration of a single pressure perfusion, and the final free nitrite ion content is greatly improved; (3) The present invention can monitor the perfusion operation of multiple perfusion points at one time, without the need to independently control the perfusion of each mortgage perfusion device in sequence, and is convenient for uniformly adjusting the perfusion pressure and dosage according to the amount of coating. (4) The present invention uses a circulation pipeline to form a stable liquid circulation pool, and the pressure of its circulation pipeline will not produce large fluctuations as the amount of low-pressure perfusion device increases, and a single one is convenient for stable control. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is the natural potential diagram of the steel bars after 0, 3, 6, and 9 months in Example 1 of the present invention; Figure 2 0, 3, 6, and 9 months after the steel bars of Comparative Example 1 of the present invention are shown in FIG. Figure 3 Is the natural potential diagram of the steel bars after 0, 3, 6, and 9 months in Comparative Example 3 of the present invention; Figure 4 It is the pipeline connection diagram of embodiment 3 of the invention.

[0017] In the figure: 1. low-pressure injector, 2. liquid inlet branch pipe, 3. liquid inlet main pipe, 4. first electromagnetic pressure valve, 5. pump body, 6. second electromagnetic pressure valve. DETAILED DESCRIPTION

[0018] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0019] Unless otherwise defined, all technical terms and scientific terms used in the present invention have the same meanings as those generally understood by ordinary technicians in the field to which the present disclosure belongs. Unless otherwise specified, the raw materials and equipment used in the present invention are conventional raw materials and equipment in the field, which can be obtained from conventional commercial channels; the methods used in the present invention are conventional methods in the field unless otherwise specified. Some of the raw materials and manufacturer information used in the present invention are as follows: Portland cement: P•O 42.5R ordinary Portland cement produced by Zhejiang Bo Hai Luo Cement Co., Ltd.; river sand: medium sand from Ningbo Global Concrete Co., Ltd.; gravel: crushed stone from the quarry in Ningbo area, the surface of the crushed stone is rough and hard, and meets the requirements of the national standard GB / T14685; steel bar: the steel bar used in this article is HPB235 grade smooth round steel bar with a diameter of 13mm. The absorbent in the present invention is a sponge.

[0020] Example 1: A method for repairing steel bars in marine concrete on site using a rust-inhibiting composition, comprising the following steps: (1) Delineate the repair area and use a steel bar position measuring instrument to locate the steel bars in the repair area; use a corrosion rate tester to measure the corrosion rate and corrosion current, use a natural potential electrode measuring instrument to measure the potential, and determine the coating surface and injection point; (2) Pre-treat the outer surface of marine concrete at the painting surface and pouring point; (3) Mix the rust-inhibiting composition with water to prepare an aqueous solution of the rust-inhibiting composition; apply the aqueous solution of the rust-inhibiting composition to the pre-treated surface; when applying, moisten the polished surface with a saturated nitrite solution to form a water film on the polished surface, cover the frosted surface with a water-absorbing material that has absorbed enough saturated nitrite solution, then cover the water-absorbing material with a waterproof material, and fix the edges of the waterproof material on the surface of the reinforced concrete structure with a seal; finally, press a heavy object on the waterproof material to compress the thickness of the water-absorbing material by more than 1 / 3, and keep it for 2 weeks; (4) Each time you apply paint, wait for a while until the surface is dry before applying it again. The total amount of paint is 1.75 At the same time, perfusion was performed at the pretreated perfusion points, the perfusion pressure was 0.1Mpa, and the perfusion volume at each perfusion point was 50ml; (5) Perform post-treatment on the repaired area after painting and pouring to confirm that the repair is complete.

[0021] In step (2), the pretreatment is to repair, clean and sand the outer surface of the marine concrete. In step (3), the injection is performed using a low-pressure injector, specifically: the base of the low-pressure injector is fixed at the injection point, the low-pressure injector absorbs the injection amount of the rust-inhibiting composition aqueous solution, the low-pressure injector is connected to the base, and 70% of the rust-inhibiting composition aqueous solution is injected into the reinforced concrete. After the injection is completed, the base is removed. In step (3), the low-pressure injector includes a base with a liquid outlet, a liquid outlet pipe and a cylinder connected to the liquid outlet pipe at one end, and the base and the liquid outlet pipe are detachably connected. In step (3), each painting is performed 3 to 5 hours after the previous painted surface has dried.

[0022] The rust-inhibiting composition comprises an anodic rust-inhibiting component A and a cathodic rust-inhibiting component B, wherein the anodic rust-inhibiting component A is sodium nitrite and the cathodic rust-inhibiting component B is benzotriazole, and the weight ratio of the two is 1:3; the Cl- content in the marine concrete is 1 The water-cement ratio of the marine concrete is in the range of 0.3, the sand ratio is 38%, the slump is 15cm, and the air content is 3%.

[0023] The amount of the rust-proofing composition added is: the molar ratio of NO2- in the rust-proofing composition to Cl- in the marine concrete is 0.8:1. The cement in the marine concrete is silicate cement, and the amount of addition is 280 , river sand with a fineness modulus of 2.6, added in an amount of 750 , crushed stone with a particle size of 10 mm, added in an amount of 1000 The steel bars in the marine concrete contain 0.2% C, 0.3% Si, 1.3% Mn, 0.2% P, 0.02% S, 0.08% Cr, 0.04% Ni and 0.01 Mo.

[0024] Example 2: A method for repairing steel bars in marine concrete on site using a rust-inhibiting composition, comprising the following steps: (1) Delineate the repair area and use a steel bar position measuring instrument to locate the steel bars in the repair area; use a corrosion rate tester to measure the corrosion rate and corrosion current, use a natural potential electrode measuring instrument to measure the potential, and determine the coating surface and injection point; (2) Pre-treat the outer surface of marine concrete at the painting surface and pouring point; (3) Mix the rust-inhibiting composition with water to prepare an aqueous solution of the rust-inhibiting composition; apply the aqueous solution of the rust-inhibiting composition to the pre-treated surface; when applying, moisten the polished surface with a saturated nitrite solution to form a layer of water film on the polished surface, cover the frosted surface with a water-absorbing material that has absorbed enough saturated nitrite solution, then cover the water-absorbing material with a waterproof material, and fix the edges of the waterproof material on the surface of the reinforced concrete structure with a seal; finally, press a heavy object on the waterproof material to compress the thickness of the water-absorbing material by more than 1 / 3, and keep it for 3 weeks; (4) Each time you apply paint, wait for a while until the surface is dry before applying it again. The total amount of paint is 2.63 At the same time, perfusion was performed at the pretreated perfusion points, the perfusion pressure was 0.2Mpa, and the perfusion volume of each perfusion point was 150ml; (5) Perform post-treatment on the repaired area after painting and pouring to confirm that the repair is complete.

[0025] In step (2), the pretreatment is to repair, clean and sand the outer surface of the marine concrete. In step (3), the pouring uses a low-pressure pourer, specifically: the base of the low-pressure pourer is fixed at the pouring point, the low-pressure pourer absorbs the pouring amount of the rust-inhibiting composition aqueous solution, the low-pressure pourer is connected to the base, and 70% of the rust-inhibiting composition aqueous solution is poured into the reinforced concrete. After the pouring is completed, the base is removed. In step (3), the low-pressure pourer includes a base with a liquid outlet, a liquid outlet pipe and a cylinder connected to the liquid outlet pipe at one end, and the base and the liquid outlet pipe are detachably connected. In step (3), each brushing is carried out 5 hours after the previous brushing surface is dry. In step (4), the post-treatment is to detect the corrosion potential and corrosion current of the steel bars in the repair area on the 7th, 90th and 180th days after brushing and pouring.

[0026] The rust-inhibiting composition comprises an anodic rust-inhibiting component A and a cathodic rust-inhibiting component B, wherein the anodic rust-inhibiting component A is sodium nitrite and the cathodic rust-inhibiting component B is benzotriazole, and the weight ratio of the two is 3:1; the Cl- content in the marine concrete is 4 The water-cement ratio of the marine concrete is in the range of 0.5, the sand ratio is 45%, the slump is 17cm, and the air content is 5%.

[0027] The amount of the rust-proofing composition added is: the molar ratio of NO2- in the rust-proofing composition to Cl- in the marine concrete is 1.2:1. The cement in the marine concrete is silicate cement, and the amount of addition is 320 , river sand with a fineness modulus of 2.8, added in an amount of 770 , crushed stone with a particle size of 20 mm, added in an amount of 1100 The steel bars in the marine concrete contain 0.3% C, 0.3-0.4% Si, 1.4% Mn, 0.3% P, 0.03% S, 0.08% Cr, 0.04% Ni, and 0.01 Mo.

[0028] Comparative Example 1: A method for repairing steel bars in marine concrete on-site using a rust-inhibiting composition, comprising the following steps: (1) Delineate the repair area and use a steel bar position measuring instrument to locate the steel bars in the repair area; use a corrosion rate tester to measure the corrosion rate and corrosion current, use a natural potential electrode measuring instrument to measure the potential, and determine the coating surface; (2) Pre-treat the outer surface of the marine concrete to be painted; (3) Mix the rust-inhibiting composition with water to prepare an aqueous solution of the rust-inhibiting composition; apply the aqueous solution of the rust-inhibiting composition to the pre-treated surface; when applying, moisten the polished surface with a saturated nitrite solution to form a water film on the polished surface, cover the frosted surface with a water-absorbing material that has absorbed enough saturated nitrite solution, then cover the water-absorbing material with a waterproof material, and fix the edges of the waterproof material on the surface of the reinforced concrete structure with a seal; finally, press a heavy object on the waterproof material to compress the thickness of the water-absorbing material by more than 1 / 3, and keep it for 2 weeks; (4) Each time you apply paint, wait for a while until the surface is dry before applying it again. The total amount of paint is 2.64 ; (5) Perform post-processing on the repaired area to confirm that the repair is complete.

[0029] The rust-proof composition comprises an anodic rust-proof component A and a cathodic rust-proof component B, wherein the anodic rust-proof component A is sodium nitrite and the cathodic rust-proof component B is benzotriazole; the Cl- content in the marine concrete is 4 The water-cement ratio of the marine concrete is in the range of 0.6, the sand ratio is 45%, the slump is 17cm, and the air content is 5%.

[0030] The rust-proofing composition comprises an anodic rust-proofing component A and a cathodic rust-proofing component B, wherein the anodic rust-proofing component A is sodium nitrite and the cathodic rust-proofing component B is benzotriazole, and the weight ratio of the two is 4:1; the amount of the rust-proofing composition added is: the molar ratio of NO2- in the rust-proofing composition to Cl- in the marine concrete is 1.2:1. The cement in the marine concrete is silicate cement, and the amount of addition is 320 , river sand with a fineness modulus of 2.8, added in an amount of 770 , crushed stone with a particle size of 20 mm, added in an amount of 1100 .

[0031] Comparative Example 2: A method for repairing steel bars in marine concrete on-site using a rust-inhibiting composition, comprising the following steps: (1) Delineate the repair area and use a steel bar position measuring instrument to locate the steel bars in the repair area; use a corrosion rate tester to measure the corrosion rate and corrosion current, use a natural potential electrode measuring instrument to measure the potential, and determine the coating surface; (2) Pre-treat the outer surface of the marine concrete to be painted; (3) Mix the rust-inhibiting composition with water to prepare an aqueous solution of the rust-inhibiting composition; apply the aqueous solution of the rust-inhibiting composition to the pre-treated surface; when applying, moisten the polished surface with a saturated nitrite solution to form a water film on the polished surface, cover the frosted surface with a water-absorbing material that has absorbed enough saturated nitrite solution, then cover the water-absorbing material with a waterproof material, and fix the edges of the waterproof material to the surface of the reinforced concrete structure with a seal; finally, press a heavy object on the waterproof material to compress the thickness of the water-absorbing material by more than 1 / 3, and keep it for 3 weeks; (4) Each time you apply paint, wait for a while until the surface is dry before applying it again. The total amount of paint is 1.74 ; (5) Perform post-processing on the repaired area to confirm that the repair is complete.

[0032] The rust-proof composition comprises an anodic rust-proof component A and a cathodic rust-proof component B, wherein the anodic rust-proof component A is sodium nitrite and the cathodic rust-proof component B is benzotriazole; the Cl- content in the marine concrete is 4 The water-cement ratio of the marine concrete is in the range of 0.3, the sand ratio is 45%, the slump is 17cm, and the air content is 5%.

[0033] The rust-proofing composition comprises an anodic rust-proofing component A and a cathodic rust-proofing component B, wherein the anodic rust-proofing component A is sodium nitrite and the cathodic rust-proofing component B is benzotriazole, and the weight ratio of the two is 4:1; the amount of the rust-proofing composition added is: the molar ratio of NO2- in the rust-proofing composition to Cl- in the marine concrete is 1.2:1. The cement in the marine concrete is silicate cement, and the amount of addition is 320 , river sand with a fineness modulus of 2.8, added in an amount of 770 , crushed stone with a particle size of 20 mm, added in an amount of 1100 .

[0034] Comparative Example 3: A method for repairing steel bars in marine concrete on-site using a rust-inhibiting composition, comprising the following steps: (1) Delineate the repair area and use a steel bar position measuring instrument to locate the steel bars in the repair area; use a corrosion rate tester to measure the corrosion rate and corrosion current, use a natural potential electrode measuring instrument to measure the potential, and determine the pouring point; (2) Pre-treat the outer surface of the marine concrete at the pouring point; (3) Mixing the rust-inhibiting composition with water to prepare an aqueous solution of the rust-inhibiting composition; pouring the solution at the pretreated pouring points at a pouring pressure of 0.2 MPa and a pouring volume of 150 ml at each pouring point; (5) Perform post-treatment on the repaired area after painting and pouring to confirm that the repair is complete.

[0035] In step (2), the pretreatment is to repair, clean and sand the outer surface of the marine concrete. In step (3), the pouring uses a low-pressure injector, specifically: the base of the low-pressure injector is fixed at the pouring point, the low-pressure injector absorbs the pouring amount of the rust-inhibiting composition aqueous solution, the low-pressure injector is connected to the base, and 70% of the rust-inhibiting composition aqueous solution is poured into the reinforced concrete. After the pouring is completed, the base is removed. In step (3), the low-pressure injector includes a base with a liquid outlet, a liquid outlet pipe and a cylinder connected to the liquid outlet pipe at one end, and the base and the liquid outlet pipe are detachably connected. In step (3), each painting is carried out 5 hours after the previous painted surface has dried.

[0036] The rust-inhibiting composition comprises an anodic rust-inhibiting component A and a cathodic rust-inhibiting component B, wherein the anodic rust-inhibiting component A is sodium nitrite and the cathodic rust-inhibiting component B is benzotriazole, and the weight ratio of the two is 1:4; the Cl- content in the marine concrete is 4 The water-cement ratio of the marine concrete is in the range of 0.2, the sand ratio is 45%, the slump is 17cm, and the air content is 5%.

[0037] The amount of the rust-proofing composition added is: the molar ratio of NO2- in the rust-proofing composition to Cl- in the marine concrete is 1.2:1. The cement in the marine concrete is silicate cement, and the amount of addition is 320 , river sand with a fineness modulus of 2.8, added in an amount of 770 , crushed stone with a particle size of 20 mm, added in an amount of 1100 The steel bars in the marine concrete contain 0.3% C, 0.3-0.4% Si, 1.4% Mn, 0.3% P, 0.03% S, 0.08% Cr, 0.04% Ni, and 0.01 Mo.

[0038] Embodiment 3: The difference between this embodiment 3 and embodiment 2 is that Figure 4As shown, the cylinders of multiple groups of low-pressure injectors 1 are externally connected to the liquid inlet branch pipe 2, and the liquid inlet branches of multiple groups of low-pressure injectors are connected in parallel to the liquid inlet main pipe 3. The liquid inlet branch pipe is equipped with a first electromagnetic pressure valve 4, and the electromagnetic valve is externally connected to a control system. The control system controls the pressure of the electromagnetic pressure valve. The liquid inlet main pipe is connected to a circulation pipeline, one of which is equipped with a pump body 5. A second electromagnetic pressure valve 6 is provided on the circulation pipeline in parallel with the liquid inlet branch. When the second electromagnetic pressure valve is closed, the control system controls the first electromagnetic pressure valve to adjust the low-pressure injector so that its pressure is 0.1-0.2Mpa. The control system collects the start-up time of the first electromagnetic pressure valve and the second electromagnetic pressure valve so that the injection amount of each injection point is controlled to be 50-150ml. This embodiment can monitor the injection operation of multiple injection points at one time, and does not need to independently control the injection of each mortgage injector in sequence, which is convenient for uniformly adjusting the injection pressure and dosage according to the amount of brushing. This embodiment utilizes a circulation pipeline to form a stable liquid circulation pool, and the pressure of the circulation pipeline will not fluctuate greatly as the amount of low-pressure injector used increases, and can be easily and stably controlled individually.

[0039] The present invention conducts corrosion resistance tests on the corrosion-resistant reinforced concrete structures obtained in Examples 1-2 and Comparative Examples 1-3, and conducts the following experiments: (1) The natural potential of the steel bars after each repair action of 0m, 3m, 16m, and 9m is measured by a natural electrode potential measuring instrument to evaluate the corrosion state of the steel bars and the rust resistance of each repair action. The measurement is performed using a saturated copper sulfate solution electrode, and the evaluation criteria are as follows: E>-200mV No corrosion with a probability of more than 90% -200mV>E>-350mV Uncertain E<-350mV will corrode with a probability of more than 90%, (2) Determination of corrosion area rate: After splitting the concrete specimen, the steel bars were taken out and 30 mm was cut off at both ends of the steel bars. The corroded parts were described and blackened with transparent sulfuric acid paper. Then the area of ​​the corroded parts and the corrosion area rate P were calculated. The test results are shown in Table 1. The calculation formula of the corrosion area rate is: Corrosion area rate = (corrosion area / total metal surface area) × 100%; (3) Determination of weight loss rate: According to GB / T50082-2009 "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete", the steel bars were immersed in a 10% ammonium citrate solution for rust removal, and the weight loss rate was calculated after weighing. The test results are shown in Table 1. The calculation assumes that the density and diameter of the steel bars before corrosion are uniform. The weight loss rate calculation formula is: Weight loss rate = (weight of the steel bar before rusting - weight of the steel bar after corrosion) / weight of the steel bar before rusting × 100%.

[0040] (4) Determination of free nitrite ion content: Using the above-mentioned Z1A portable drilling rig, after brushing and pressure injection of high-concentration calcium nitrite solution, collect concrete powder samples at a depth of 30 mm (on the surface of the steel bar) on site regularly (14 days, 28 days, 180 days, and 270 days), and sieve them with a sieve with an aperture of 0.15 mm. Extract free nitrite ions according to the methods in Chapter 3, and use a 722S spectrophotometer to detect ion concentration in accordance with GB12763.4-2007 "Marine Survey Specifications".

[0041] The natural electrode potentials of Example 1, Comparative Example 1 and Comparative Example 3 were measured as follows: Figure 1 , Figure 2 and Figure 3 By comparing the above figures, we can see that: The average natural potential of the natural potential of the steel bars after 0, 3, 6, and 9 months of Example 1 is -385mV, -270mV, -250mV, and -221mV, respectively. It can be seen that the red area indicating that more than 90% of the corrosion may be reduced and faded significantly with the increase of time, indicating that in practical engineering applications, the surface of the structure can play a good role in rust prevention by combining brushing and pressure perfusion of 70% calcium nitrite solution. The average natural potential of the natural potential of the steel bars after 0, 3, 6, and 9 months of Comparative Example 1 is -413mV, -409mV, -384mV, and -353mV, respectively. It can be seen that the red area indicating that more than 90% of the corrosion may be reduced with the increase of time, but it is not obvious, and the effect is not as obvious as the composite brushing plus perfusion of nitrite solution in Example 1. The natural potential of the steel bars after 0, 3, 6, and 9 months of Comparative Example 3, the average natural potential is -394mV, -367mV, -336mV, and -327mV, respectively. The same effect is not as obvious as the composite brushing and injection of nitrite solution in Example 1.

[0042] The test data of the steel bar corrosion area rate and weight loss rate of Example 1, Example 2 and Comparative Examples 1 and 3 of the present invention are shown in Table 1 (Test Table of Steel Bar Corrosion Area Rate and Weight Loss Rate).

[0043]

[0044] From Table 1, we can see that the total amount of paint is 1.75~2.63 , can effectively prevent rust, when the total amount of paint is less than 1.75 When the total amount of paint is greater than 2.63 When the total amount of coating is too large, the rust-proof effect will not be improved. The reason is that the total amount of coating is insufficient, resulting in insufficient nitrite ion concentration and insufficient penetration, which causes macrocells on the surface of the steel bar, causing macrocell corrosion. When the total amount of coating is too large, the excess rust inhibitor cannot effectively penetrate into the concrete, but stays on the concrete surface to form a thicker coating. The corrosion area and weight loss rate of Examples 1 and 2 are much smaller than those of Comparative Examples 1-3, indicating that the corrosion-resistant reinforced concrete structure prepared by the invention has a good rust-proof effect and high protection durability.

[0045] The free nitrite ion content test data of Example 1, Example 2 and Comparative Examples 1 and 3 of the present invention are shown in the following Table 2 (Free nitrite ion content table).

[0046]

[0047] As can be seen from Table 2, the trend of increasing over time indicates that after the high-concentration nitrite solution is supplied to the interior of the test column by brushing, pressure perfusion or combined action, the concentration of nitrite ions at a depth of 30 mm at each point increases over time, causing the ions to migrate to the surface of the steel bar. Under the combined action of coating and pressure perfusion in Example 1 of the present invention, the concentration of each point can be improved as a whole, making up for the shortcomings of slow penetration of single coating and uneven penetration of single pressure perfusion, and the final free nitrite ion content is much higher than that of Comparative Examples 1 and 3.

[0048] The above description is only a preferred embodiment of the present invention, and does not limit the patent protection scope of the present invention. Any equivalent structural transformation made by using the contents of the present invention and the drawings, directly or indirectly used in other related technical fields, is also included in the protection scope of the present invention.

Claims

1. A method for repairing steel bars in marine concrete on site using a rust-resistant composition, characterized in that: The following steps are involved: (1) Delineate the repair area and use a steel bar position measuring instrument to locate the steel bars in the repair area; Determine the corrosion rate and corrosion current, and determine the potential, and determine the coating surface and injection point; (2) Pre-treat the outer surface of marine concrete at the painting surface and pouring point; (3) Mix the rust-inhibiting composition with water to prepare an aqueous solution of the rust-inhibiting composition; apply the aqueous solution of the rust-inhibiting composition to the pre-treated surface; when applying, moisten the polished surface with a saturated nitrite solution to form a water film on the polished surface, cover the frosted surface with a water-absorbing material that has absorbed enough nitrite aqueous solution, then cover the water-absorbing material with a waterproof material, and fix the edges of the waterproof material on the surface of the reinforced concrete structure with a seal; finally, press a heavy object on the waterproof material to compress the thickness of the water-absorbing material by more than 1 / 3, and keep it for 2 to 3 weeks; (4) Each time you apply paint, wait for a while until the surface is dry before applying it again. The total amount of paint applied is 1.75~2.63kg / m 3 At the same time, perfusion is performed at the pretreated perfusion points, the perfusion pressure is 0.1-0.2Mpa, and the perfusion volume of each perfusion point is 50-150ml; (5) Perform post-treatment on the repaired area after painting and pouring to confirm that the repair is complete.

2. A method for on-site repair of steel bars in marine concrete using a rust-resistant composition according to claim 1, characterized in that: In step (2), the pretreatment is to repair, clean and sand the outer surface of the marine concrete.

3. A method for on-site repair of steel bars in marine concrete using a rust-resistant composition according to claim 2, characterized in that: In step (3), the pouring is performed using a low-pressure pourer, specifically: the base of the low-pressure pourer is fixed at the pouring point, the low-pressure pourer draws a pouring amount of the rust-inhibiting composition aqueous solution, the low-pressure pourer is connected to the base, the rust-inhibiting composition aqueous solution is poured into the reinforced concrete, and the base is removed after the pouring is completed.

4. A method for on-site repair of steel bars in marine concrete using a rust-inhibiting composition according to claim 2, characterized in that: In step (3), the low-pressure infusion device includes a base with a liquid outlet, a liquid outlet pipe and a cylinder body with one end connected to the liquid outlet pipe, and the base and the liquid outlet pipe are detachably connected.

5. A method for on-site repair of steel bars in marine concrete using a rust-inhibiting composition according to claim 1, 2, 3 or 4, characterized in that: In step (3), each application should be done after the previously applied surface has dried for 3 to 5 hours.

6. A method for on-site repair of steel bars in marine concrete using a rust-resistant composition according to claim 1, 2, 3 or 4, characterized in that: The rust-inhibiting composition comprises an anodic rust-inhibiting component A and a cathodic rust-inhibiting component B, wherein the anodic rust-inhibiting component A is sodium nitrite and the cathodic rust-inhibiting component B is benzotriazole, and the weight ratio of the two is 1 to 9:

3.

7. A method for on-site repair of steel bars in marine concrete using a rust-inhibiting composition according to claim 1, 2, 3 or 4, characterized in that: Cl in marine concrete - Content is 1~4 kg / m 3 The water-cement ratio of the marine concrete is in the range of 0.3-0.5, the sand ratio is 38-45%, the slump is 15-17cm, and the air content is 3-5%.

8. A method for on-site repair of steel bars in marine concrete using a rust-inhibiting composition according to claim 7, characterized in that: The amount of the rust-proof composition added is: NO2 - Cl in marine concrete - The molar ratio is 0.8~1.2:

1.

9. The method for on-site repair of steel bars in marine concrete using a rust-inhibiting composition according to claim 7, characterized in that: The cement in the marine concrete is silicate cement, and the addition amount is 280~320 kg / m 3 , river sand with a fineness modulus of 2.6~2.8, the addition amount is 750~770 kg / m 3 , the crushed stone with a particle size of 10~20mm, the addition amount is 1000~1100 kg / m 3 .

10. A method for on-site repair of steel bars in marine concrete using a rust-resistant composition according to claim 7, characterized in that: The steel bars in the marine concrete contain 0.2-0.3% C, 0.3-0.4% Si, 1.3-1.4% Mn, 0.2-0.3% P, 0.02-0.03% S, 0.08-0.09% Cr, 0.04-0.05% Ni, and 0.01-0.02% Mo.

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