Construction method of corrosion-resistant reinforced concrete structure

Abstract

The invention relates to the field of reinforced concrete reconstruction construction, and discloses a construction method of an anti-corrosion reinforced concrete structure, which comprises the following steps: mixing Portland cement, fine aggregate, coarse aggregate, calcium chloride, a water reducing agent and water into concrete, and preparing a reinforced concrete prefabricated part; the two ends of the reinforced concrete prefabricated part are smeared with a preservative, the surface of the reinforced concrete prefabricated part is covered with a waterproof layer, closed curing is conducted for 26-28 days at the temperature of 20-22 DEG C, then alternate curing is conducted, and the reinforced concrete component is manufactured and put into use; and after the reinforced concrete member is put into use for 180-270 days, the surface of the reinforced concrete member is coated with a nitrite type corrosion inhibitor, after the reinforced concrete member is placed for t1 time, supplementary brushing is conducted, the supplementary brushing amount is 1 / 3-1 / 2 of the brushing amount, and the corrosion-resisting reinforced concrete structure is obtained. The corrosion-resistant reinforced concrete structure prepared through the method is good in corrosion-resistant effect and high in protection durability, and corrosion of marine concrete in the marine environment can be effectively prevented.

Description

Technical Field

[0001] The invention relates to the field of reinforced concrete reconstruction construction, and in particular to a construction method for a corrosion-resistant reinforced concrete structure. Background Art

[0002] In civil engineering, reinforced concrete structures are widely used. They are composite structures that can withstand both pressure and tension, and have high structural strength, stiffness and stability. However, as the service time increases, reinforced concrete structures will deteriorate, and the durability of reinforced concrete needs to be solved urgently. The corrosion of steel bars is a key factor affecting the durability of reinforced concrete. The corrosive medium invades the interior of the reinforced concrete structure along cracks and pores, accelerating the performance degradation of the structure, leading to cracking of the concrete protective layer, a decrease in the bond strength between steel bars and concrete, and a decrease in the bearing capacity of components.

[0003] The corrosion protection measures for reinforced concrete mainly include the concrete surface outer 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 CN106738234A discloses a production process for a corrosion-resistant prefabricated reinforced concrete inspection well, which first performs anti-corrosion processing on the steel bar, applies a mixed coating of polyurethane and graphene on the steel bar, and then casts it with concrete. After completion, it is cured and steamed, and after demoulding, a polyurethane resin coating and a zinc alloy coating are applied to the surface in sequence. However, the above method is not suitable for marine concrete in a marine environment. Marine concrete contains a large amount of chloride ions, and the outer coating on the concrete surface cannot prevent the chloride ions inside the concrete from corroding the steel bar. Although there is a coating on the surface of the steel bar, the continuous erosion of chloride ions inside the concrete and the marine environment will accelerate the failure of the coating. The coating on the surface of the steel bar is not easy to be re-coated, and the protection durability is poor. Summary of the invention

[0004] In order to solve the above-mentioned technical problem of being unable to provide continuous corrosion protection for marine concrete in a marine environment, the present invention provides a construction method for a corrosion-resistant reinforced concrete structure, which has good corrosion resistance and high protection durability, and can effectively prevent the corrosion of marine concrete in a marine environment.

[0005] The specific technical solution of the present invention is: a construction method of a corrosion-resistant reinforced concrete structure, comprising the following steps: 1) Mixing silicate cement, fine aggregate, coarse aggregate, calcium chloride, water reducing agent and water into concrete to prepare reinforced concrete precast parts; 2) Apply antiseptic to both ends of the reinforced concrete prefabricated parts, cover the surface with a waterproof layer, and perform closed curing at 20-22°C for 26-28 days, then perform alternating curing to obtain reinforced concrete components and put them into use; the alternating curing process is 47-49 hours of high temperature and high humidity curing and 23-25 ​​hours of low temperature and dry curing, which are performed alternately for 30 times, wherein the high temperature and high humidity curing temperature is 59-61°C and the humidity is 97-98%, and the low temperature and dry curing temperature is 19-21°C and the humidity is 39-41%; 3) After the reinforced concrete components are put into use for 180-270 days, the nitrite type rust inhibitor is applied on the surface. After t1 time, it is reapplied with 1 / 3 to 1 / 2 of the applied amount to obtain a corrosion-resistant reinforced concrete structure; t1 is the time when the nitrite ion concentration at 25 mm from the surface reaches the maximum value. The nitrite ion concentration is calculated by the following formula: ; in is the nitrite ion concentration, is the initial nitrite ion concentration in the concrete, C0 is the initial concentration of the coating layer, t is the placement time of the reinforced concrete after coating, the sulfite effluent coefficient K is 0.274% / month, the distance x from the sampling point to the concrete surface is 25mm, and the nitrite diffusion coefficient D is 33mm 2 / moon.

[0006] The curing process of this scheme includes closed curing and alternating curing. Closed curing allows the concrete to initially set, high temperature and high humidity can further hydrate the cement particles inside the concrete that have not been fully hydrated, thereby enhancing the strength of the concrete, and low-temperature drying curing helps to slowly evaporate the water inside the concrete and optimize the pore structure, thereby enhancing the durability and crack resistance of the concrete; through alternating high temperature and high humidity and low temperature drying, the stress inside the concrete can be released and balanced, reducing internal cracks caused by temperature changes, thereby reducing the invasion channels of corrosive media, and at the same time, alternating curing can simulate the temperature and humidity changes that concrete may encounter in the actual use environment, allowing it to gradually adapt to such changes and improve its stability and durability in complex environments.

[0007] After the reinforced concrete components are put into use, the surface of the reinforced concrete components is brushed with nitrite-type rust inhibitors. Nitrite ions penetrate into the concrete through migration, inhibiting the corrosion of steel bars. As time goes by, the concentration of nitrite ions on the concrete surface gradually decreases due to penetration. At the same time, although the concentration of nitrite ions inside the concrete is on the rise in the early stage, it will decrease after reaching the t1 time due to the decrease in penetration rate, diffusion and reaction. After the nitrite ion concentration reaches the maximum value, the surface of the reinforced concrete components is brushed again to replenish nitrite ions, which can replenish nitrite ions reduced by natural consumption or reaction in time and maintain the effective concentration of nitrite ions inside the concrete. At the same time, sufficient time is given to nitrite ions to react with the steel bar surface, thereby extending the protective effect time of the rust inhibitor, enhancing the overall corrosion resistance of the reinforced concrete structure, effectively slowing down the corrosion rate of the steel bars, and improving the durability and safety of the structure. Since the minimum thickness of the concrete protective layer is δ=25mm as specified in the concrete structure design specification, the distance of 25mm from the concrete surface is used as the sampling point.

[0008] Preferably, in step 1), the prefabricated reinforced concrete part has Cl - Content is 0.1~0.65 kg / m 3 , the gas content is 4~6%.

[0009] Preferably, in step 3), the nitrite type rust inhibitor is a rust inhibitor composition comprising an anodic rust inhibitor component A and a cathodic rust inhibitor component B, wherein the anodic rust inhibitor component A is sodium nitrite, and the cathodic rust inhibitor component B is benzotriazole, and the weight ratio of the two is 1-9:3, and the coating amount of the nitrite type rust inhibitor is 1.75-2.63 kg / m 3 .

[0010] The combination of sodium nitrite and benzotriazole has a stable and good rust-proof effect. This is because nitrite ions form a protective film of Fe2O3 on the surface of the steel bar, which hinders the anodic dissolution of iron. The adsorption of nitrite ions on the iron surface reduces the free energy of the system, making passivation easier and providing anodic protection for the steel bar. Benzotriazole reacts with the steel bar to form a multilayer protective film Fe n (Cl) p (BTA) m It tightly covers the surface of the steel bar, preventing the entry of chloride ions and providing cathodic protection for the steel bar. Under the synergistic effect of the two, it provides both anodic and cathodic protection for the steel bar, forming a dense protective film on the surface of the steel bar, effectively protecting the steel bar and preventing rust for a long time.

[0011] The total amount of paint is 1.75~2.63 kg / m 3When the amount of additional paint is 1 / 3 to 1 / 2 of the amount of paint applied, it can effectively prevent rust. When the total amount of paint applied is less than 1.75 kg / m 3 When the total amount of nitrite ions is greater than 2.63 kg / m, the nitrite ion concentration is insufficient and the penetration is insufficient, so that macro cells are formed on the surface of the steel bars, causing macro cell corrosion. 3 The reason is that the penetration capacity of the rust inhibitor is limited. When the total amount of paint 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, affecting the air permeability of the concrete. After the re-brush, the nitrite ions fully penetrate and cover the surface of the steel bar and react with the metal ions on the surface of the steel bar to achieve effective corrosion protection. - / Cl - Molar ratio, forming an effective protective film. At this time, even if the amount of brushing is increased, no more effective ingredients will participate in the reaction, so the rust prevention effect will not be further improved. In order to achieve effective corrosion protection, NO2 - / Cl - The molar ratio is at least 0.5.

[0012] Preferably, in step 1), the water-cement ratio of the reinforced concrete prefabricated part is 0.3-0.5.

[0013] When the water-cement ratio is too small, the density of the reinforced concrete components is too large, the rust inhibitor has poor permeability, and the performance of the test block in resisting the erosion of external harmful ions is improved; when the water-cement ratio is too large, the pores of the reinforced concrete components are too many, and the corrosive medium is easy to invade. At the same time, the increase in porosity will reduce the strength of the concrete, and then reduce the durability of the concrete.

[0014] Preferably, in step 1), the strength grade of the silicate cement is 42.5, and the addition amount is 280-320 kg / m 3 The fine aggregate is river sand with a fineness modulus of 2.6-2.8, and the addition amount is 750-770 kg / m 3 The coarse aggregate is crushed stone with a particle size of 5 to 20 mm and the addition amount is 1000 to 1100 kg / m 3 The water reducer is a carboxylic acid water reducer, and the addition amount is 4.5~5.0kg / m 3 .

[0015] Preferably, in step 2), the preservative is epoxy resin.

[0016] Preferably, in step 3), the specific coating process is: pre-treating the surface of the reinforced concrete component, and coating the nitrite-based rust inhibitor on the pre-treated surface of the reinforced concrete component in multiple times, with each coating being conducted after a certain period of time after the previously coated surface has dried.

[0017] Multiple applications can ensure that the rust inhibitor covers the surface of reinforced concrete components more evenly, reducing omissions or weak areas. Each application should be done after the previous application has dried. This can avoid mutual interference between the coating layers and allow the nitrite-based rust inhibitor to fully exert its effect and enhance the rust-inhibiting effect. At the same time, multiple applications can increase the bonding strength between the rust inhibitor coating and the surface of reinforced concrete components, making the coating more firmly attached to the surface and facilitating the penetration of nitrite ions.

[0018] Preferably, in step 3), the pretreatment is to repair, clean and sand the surface of the reinforced concrete component.

[0019] Pretreatment can restore surface flatness, remove surface impurities, increase surface roughness, and improve the penetration of rust inhibitors.

[0020] Preferably, in step 3), the amount of each application is 25-50 ml.

[0021] Preferably, in step 3), each application is performed after the previously applied surface has dried for 3 to 5 hours.

[0022] Compared with the prior art, the present invention has the following advantages: (1) Good corrosion resistance: The present invention releases and balances the stress inside the concrete through alternating curing, reduces internal cracks caused by temperature changes, and reduces the invasion channels of corrosive media. At the same time, alternating curing can simulate the temperature and humidity changes that concrete may encounter in the actual use environment, so that it can gradually adapt to such changes and improve its stability and durability in complex environments. By brushing and re-brushing nitrite-type rust inhibitors on the surface of reinforced concrete components, nitrite ions can fully penetrate and cover the surface of the steel bars and react with the metal ions on the surface of the steel bars to form an effective protective film with good corrosion resistance. (2) High protection durability: By re-brushing the surface of reinforced concrete components, nitrite ions are supplemented to keep the nitrite ion concentration within a relatively stable range, ensuring that the effective nitrite ion concentration can be maintained inside and on the surface of the concrete, thereby continuously inhibiting the corrosion of the steel bars by chloride ions and extending the service life of the reinforced concrete structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 1 is a graph showing the change of nitrite ion concentration at 25 mm from the surface of the reinforced concrete member prepared in Example 1 of the present invention over time. DETAILED DESCRIPTION

[0024] The present invention is described below by specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. Without departing from the spirit and scope of the inventive concept, changes and advantages that can be thought of by those skilled in the art are included in the present invention, and the attached claims and any equivalents thereof are the protection scope of the present invention.

[0025] Unless otherwise defined, all technical terms and scientific terms used in the present invention have the same meanings as those commonly 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 and can be obtained from conventional commercial channels; unless otherwise specified, the methods used in the present invention are conventional methods in the field.

[0026] Some of the raw materials and manufacturer information used in this invention are as follows: Portland cement: P•O 42.5R ordinary Portland cement produced by Zhejiang Ningbo Conch Cement Co., Ltd.; River sand: from Ningbo Global Concrete Co., Ltd., medium sand; Stone: The stone is from Ningbo quarry, the surface of the stone is rough and hard, and it meets the requirements of national standard GB / T14685; Steel bars: The steel bars used in this paper are HPB235 grade plain round steel bars with a diameter of 13 mm.

[0027] Embodiment 1: This embodiment provides a construction method for a corrosion-resistant reinforced concrete structure, comprising the following steps: (1) Build the steel skeleton, clean the mold, apply the release agent, and place the steel skeleton into the mold; (2) Put silicate cement, fine aggregate, coarse aggregate, calcium chloride, water reducer and water into a mixer and stir. The strength grade of silicate cement is 42.5 and the addition amount is 300 kg / m 3 The fine aggregate is river sand with a fineness modulus of 2.7, and the addition amount is 760 kg / m 3 The coarse aggregate is crushed stone with a particle size of 5-10 mm and an addition amount of 1080 kg / m 3 , the water is tap water, the addition amount is 90 kg / m 3 , the amount of calcium chloride added is 0.17 kg / m 3 The water reducer is a carboxylic acid water reducer, and the addition amount is 4.8kg / m 3 , the mixing time is 4h, so that all the raw materials are fully mixed together to obtain concrete, the air content of the concrete is 4%, and the water-cement ratio is 0.3; (3) Pour concrete into the mold and vibrate it with a vibrator to ensure that the concrete is dense and free of bubbles and voids. Allow it to stand for molding and remove it from the mold after 1 day of molding and curing to obtain a reinforced concrete prefabricated part. (4) Apply epoxy resin to both ends of the reinforced concrete prefabricated parts to prevent the ends of the steel bars from being exposed to the air and causing corrosion. Then wrap the surface of the reinforced concrete prefabricated parts with a waterproof layer. The waterproof layer can be a plastic film or other waterproof and airtight materials to slow down the evaporation rate of water on the concrete surface, allowing the hydration reaction to proceed fully, while preventing the concrete surface from being eroded and damaged by the outside. (5) The reinforced concrete prefabricated parts wrapped with the waterproof layer are placed in a curing room for closed curing for 28 days. The temperature in the curing room is 20°C and the humidity is 95%. The reinforced concrete prefabricated parts after closed curing are placed in a high temperature and high humidity curing box for alternating curing. The alternating curing is a cycle curing of 48 hours of high temperature and high humidity curing and 24 hours of low temperature dry curing. The cycle is repeated 30 times. During the high temperature and high humidity curing, the temperature in the high temperature and high humidity curing box is 60°C and the humidity is 98%. The cement particles that are not completely hydrated in the concrete are further hydrated, thereby enhancing the strength of the concrete. During the low temperature dry curing, the temperature in the high temperature and high humidity curing box is 20°C and the humidity is 40%, which is conducive to the slow evaporation of the water in the concrete and the optimization of the pore structure, thereby enhancing the durability and crack resistance of the concrete. After alternating curing, the reinforced concrete components are obtained and put into use at the seaside. (6) After 180 days of use, reinforced concrete components shall be subjected to rust prevention maintenance. Pre-treatment shall be carried out on the surface. Cement mortar shall be used to repair obvious defects such as honeycombs and exposed stones. Surface debris and loose attachments shall be removed with a steel spatula. Oil stains shall be removed with appropriate solvents such as acetone. Finally, the components shall be rinsed with deionized water. The concrete surface shall be polished with sandpaper. A 70% concentration of nitrite-based rust inhibitor shall be prepared into a nitrite-based rust inhibitor aqueous solution. The polished surface shall be moistened to form a layer of water film, which is conducive to the subsequent penetration of nitrite ions. The nitrite-based rust inhibitor aqueous solution shall be applied to the pre-treated reinforced concrete component surface in multiple times, with 25 ml applied each time. Each application shall be carried out after 4 hours after the previous application has dried. The total amount of application is 1.75 kg / m 3 ; The above-mentioned nitrite-type rust inhibitor is a composition of sodium nitrite and benzotriazole, wherein the weight ratio of sodium nitrite to benzotriazole is 1:1; (7) After the painting is completed, it is allowed to stand for t1 time before re-painting. The pretreatment and rust remover used during re-painting are the same as those used during painting. A 70% concentration of nitrite-based rust inhibitor aqueous solution is re-painted on the surface of the reinforced concrete component in multiple times, 25 ml each time, and the total amount of re-painting is 1 / 2 of the total amount of painting, thus obtaining a corrosion-resistant reinforced concrete structure; t1 is the time when the nitrite ion concentration at 25 mm from the surface reaches the maximum value, and the nitrite ion concentration is calculated by the following formula: ; in is the nitrite ion concentration, is the initial nitrite ion concentration in the concrete, C0 is the initial concentration of the coating layer, t is the placement time of the reinforced concrete after coating, the sulfite effluent coefficient K is 0.274% / month, the distance x from the sampling point to the concrete surface is 25mm, and the nitrite diffusion coefficient D is 33mm 2 / moon.

[0028] The derivation process of the calculation formula of the above nitrite ion concentration is as follows.

[0029] The diffusion process of nitrite into concrete can be expressed by Fick's second law: (1); Where C is the concentration of nitrite in concrete at a distance x from the surface (%); t — time (month); x — distance from the concrete surface (mm); D — diffusion coefficient of nitrite in concrete (mm 2 / moon).

[0030] To solve equation (1), boundary conditions need to be set. Assuming that the coating thickness is H, the nitrite ion concentration C (x, t) of the coating is only a function of time. At this time, the boundary conditions can be considered as: ; (2); (3); Where C0(t) is the initial concentration of the coating layer (%).

[0031] To solve equation (1), make variable substitution: , (4).

[0032] Substituting formula (4) into formula (1) yields: (5); Where C0 is the initial concentration of the coating layer (%).

[0033] Integrating the ordinary differential equation twice gives: (6).

[0034] Substituting K1 and K2 into formula (6) yields: (7).

[0035] Assuming that the outflow of nitrite from the coating layer is proportional to the nitrite ion concentration, the initial concentration of the coating layer can be expressed as: (8); Where K is the outflow coefficient (% / month).

[0036] Substituting formula (8) into formula (7) yields the diffusion concentration of nitrite in concrete: (9).

[0037] In order to obtain the initial concentration C0 of the coating layer and the nitrite outflow coefficient K, equation (8) is converted into the following equation: (10); According to the measured concentration of the coating layer in Table 1, linear regression is performed on formula (10), and the linear regression equation is obtained: Y = 0.274x + 2.123; therefore K = 0.274% / month, C0 = 0.471%.

[0038] Table 1 Distribution of nitrite concentration in concrete ; The diffusion coefficient D can be solved by the least square method. 2 After substituting into formula (9), the nitrite ion concentration C(x) at 0 to 50 mm from the surface in the 12th month is calculated. i ,12), so that C(x i , 12) and the measured nitrite osmotic concentration C shown in Table 1 M The square sum of the difference M is the smallest. After numerical analysis, the diffusion coefficient of nitrite in concrete is D=33mm 2 / moon.

[0039] Nitrite ion concentration The diffusion concentration equation derived in this paper and the initial nitrite ion concentration in concrete can be given as: (11); In the formula — Initial nitrite ion concentration in concrete (%).

[0040] Based on (11), the diffusion model is: (12); Where: — Initial chloride ion concentration in concrete (%), — Chloride ion concentration on exposed surfaces in concrete (%); Substitute the effective anti-rust molar ratio NO2 - / Cl - is 0.5, we get: (13); In the formula — Chloride ion concentration that satisfies the effective molar ratio (%).

[0041] Substituting (13) into (12), the nitrite ion concentration at 25 mm from the surface of the marine concrete can be converted into the critical chloride ion concentration suitable for this model. Figure 1 As shown, the time corresponding to the highest nitrite ion concentration is t1, and in this embodiment, t1 is 13 months.

[0042] Embodiment 2: This embodiment provides a construction method for a corrosion-resistant reinforced concrete structure, comprising the following steps: (1) Build the steel skeleton, clean the mold, apply the release agent, and place the steel skeleton into the mold; (2) Put silicate cement, fine aggregate, coarse aggregate, calcium chloride, water reducer and water into a mixer and stir. The strength grade of silicate cement is 42.5 and the addition amount is 300 kg / m 3 The fine aggregate is river sand with a fineness modulus of 2.7, and the addition amount is 760 kg / m 3 The coarse aggregate is crushed stone with a particle size of 5-10 mm and an addition amount of 1080 kg / m 3 , the water is tap water, the addition amount is 150 kg / m 3 , the amount of calcium chloride added is 0.17 kg / m 3 The water reducer is a carboxylic acid water reducer, and the addition amount is 4.8kg / m 3 , the mixing time is 4h, so that all the raw materials are fully mixed together to obtain concrete, the air content of the concrete is 4%, and the water-cement ratio is 0.5; (3) Pour concrete into the mold and vibrate it with a vibrator to ensure that the concrete is dense and free of bubbles and voids. Allow it to stand for molding and remove it from the mold after 1 day of molding and curing to obtain a reinforced concrete prefabricated part. (4) Apply epoxy resin to both ends of the reinforced concrete prefabricated parts to prevent the ends of the steel bars from being exposed to the air and causing corrosion. Then wrap the surface of the reinforced concrete prefabricated parts with a waterproof layer. The waterproof layer can be a plastic film or other waterproof and airtight materials to slow down the evaporation rate of water on the concrete surface, allowing the hydration reaction to proceed fully, while preventing the concrete surface from being eroded and damaged by the outside. (5) The reinforced concrete prefabricated parts wrapped with the waterproof layer are placed in a curing room for closed curing for 28 days. The temperature in the curing room is 22°C and the humidity is 93%. The reinforced concrete prefabricated parts after closed curing are placed in a high temperature and high humidity curing box for alternating curing. The alternating curing is a cycle curing of 47 hours of high temperature and high humidity curing and 25 hours of low temperature dry curing. The cycle is repeated 30 times. During the high temperature and high humidity curing, the temperature in the high temperature and high humidity curing box is 59°C and the humidity is 97%. The cement particles that are not completely hydrated in the concrete are further hydrated, thereby enhancing the strength of the concrete. During the low temperature dry curing, the temperature in the high temperature and high humidity curing box is 19°C and the humidity is 39%, which is conducive to the slow evaporation of the water in the concrete and the optimization of the pore structure, thereby enhancing the durability and crack resistance of the concrete. After alternating curing, the reinforced concrete components are obtained and put into use at the seaside. (6) After 180 days of use, reinforced concrete components shall be subjected to rust prevention maintenance. Pre-treatment shall be carried out on the surface. Cement mortar shall be used to repair obvious defects such as honeycombs and exposed stones. Surface debris and loose attachments shall be removed with a steel spatula. Oil stains shall be removed with appropriate solvents such as acetone. Finally, the components shall be rinsed with deionized water. The concrete surface shall be polished with sandpaper. A 70% concentration of nitrite-based rust inhibitor shall be prepared into a nitrite-based rust inhibitor aqueous solution. The polished surface shall be moistened to form a layer of water film, which is conducive to the subsequent penetration of nitrite ions. The nitrite-based rust inhibitor aqueous solution shall be applied to the pre-treated reinforced concrete component surface in multiple times, 25 ml each time. Each application shall be carried out 4 hours after the previous application has dried. The total amount of application is 2.63 kg / m 3 ; The above-mentioned nitrite-type rust inhibitor is a composition of sodium nitrite and benzotriazole, wherein the weight ratio of sodium nitrite to benzotriazole is 1:3; (7) After the painting is completed, it is allowed to stand for t1 time before re-painting. The pretreatment and rust remover used during re-painting are the same as those used during painting. A 70% concentration of nitrite-based rust inhibitor aqueous solution is re-painted on the surface of the reinforced concrete component in multiple times, 25 ml each time, and the total amount of re-painting is 1 / 2 of the total amount of painting, thus obtaining a corrosion-resistant reinforced concrete structure; t1 is the time when the nitrite ion concentration at 25 mm from the surface reaches the maximum value. The nitrite ion concentration is calculated by the following formula: ; in is the nitrite ion concentration, is the initial nitrite ion concentration in the concrete, C0 is the initial concentration of the coating layer, t is the placement time of the reinforced concrete after coating, the sulfite effluent coefficient K is 0.274% / month, the distance x from the sampling point to the concrete surface is 25mm, and the nitrite diffusion coefficient D is 33mm 2 / moon.

[0043] Embodiment 3: This embodiment provides a construction method for a corrosion-resistant reinforced concrete structure, comprising the following steps: (1) Build the steel skeleton, clean the mold, apply the release agent, and place the steel skeleton into the mold; (2) Put silicate cement, fine aggregate, coarse aggregate, calcium chloride, water reducer and water into a mixer and mix them. The strength grade of silicate cement is 42.5 and the addition amount is 320 kg / m 3 The fine aggregate is river sand with a fineness modulus of 2.6, and the addition amount is 770 kg / m 3 The coarse aggregate is crushed stone with a maximum particle size of 20 mm and an addition amount of 1100 kg / m 3 , the water is tap water, the addition amount is 96 kg / m 3 , calcium chloride addition amount is 1.0 kg / m 3 The water reducer is a carboxylic acid water reducer, and the addition amount is 4.5 kg / m 3 , the mixing time is 4h, so that all the raw materials are fully mixed together to obtain concrete, the air content of the concrete is 6%, and the water-cement ratio is 0.3; (3) Pour concrete into the mold and vibrate it with a vibrator to ensure that the concrete is dense and free of bubbles and voids. Allow it to stand for molding and remove it from the mold after 1 day of molding and curing to obtain a reinforced concrete prefabricated part. (4) Apply anticorrosive agent to both ends of the reinforced concrete prefabricated parts to prevent the ends of the steel bars from being exposed to the air and causing corrosion. Then wrap the surface of the reinforced concrete prefabricated parts with a waterproof layer. The waterproof layer can be a plastic film or other waterproof and airtight materials to slow down the evaporation rate of water on the concrete surface, so that the hydration reaction can proceed fully and prevent the concrete surface from being eroded and damaged by the outside. (5) The reinforced concrete prefabricated parts wrapped with the waterproof layer are placed in a curing room for closed curing for 28 days. The temperature in the curing room is 20°C and the humidity is 95%. The reinforced concrete prefabricated parts after closed curing are placed in a high temperature and high humidity curing box for alternating curing. The alternating curing is a cycle curing of 49 hours of high temperature and high humidity curing and 23 hours of low temperature dry curing. The cycle is repeated 30 times. During the high temperature and high humidity curing, the temperature in the high temperature and high humidity curing box is 61°C and the humidity is 97%. The cement particles that are not completely hydrated in the concrete are further hydrated, thereby enhancing the strength of the concrete. During the low temperature dry curing, the temperature in the high temperature and high humidity curing box is 21°C and the humidity is 41%, which is conducive to the slow evaporation of the water in the concrete and the optimization of the pore structure, thereby enhancing the durability and crack resistance of the concrete. After alternating curing, the reinforced concrete components are obtained and put into use at the seaside. (6) After 270 days of use, reinforced concrete components shall be subjected to rust prevention maintenance. Pre-treatment shall be carried out on the surface. Cement mortar shall be used to repair obvious defects such as honeycombs and exposed stones. Surface debris and loose attachments shall be removed with a steel spatula. Oil stains shall be removed with appropriate solvents such as acetone. Finally, the components shall be rinsed with deionized water. The concrete surface shall be polished with sandpaper. A 70% concentration of nitrite-based rust inhibitor shall be prepared into a nitrite-based rust inhibitor aqueous solution. The polished surface shall be moistened to form a layer of water film, which is conducive to the penetration of nitrite ions. The nitrite-based rust inhibitor aqueous solution shall be applied to the pre-treated reinforced concrete component surface in multiple times, with 25 ml applied each time. Each application shall be carried out 3 hours after the previous application has dried. The total amount of application is 2.63 kg / m 3 ; The above-mentioned nitrite-type rust inhibitor is a composition of sodium nitrite and benzotriazole, wherein the weight ratio of sodium nitrite to benzotriazole is 3:1; (7) After the painting is completed, it is allowed to stand for t1 time before re-painting. The pretreatment and rust remover used during re-painting are the same as those used during painting. A 70% concentration of nitrite-based rust inhibitor aqueous solution is re-painted on the surface of the reinforced concrete component in multiple times, 25 ml each time, and the total amount of re-painting is 1 / 3 of the total amount of painting, thus obtaining a corrosion-resistant reinforced concrete structure; t1 is the time when the nitrite ion concentration at 25 mm from the surface reaches the maximum value. The nitrite ion concentration is calculated by the following formula: ; in is the nitrite ion concentration, is the initial nitrite ion concentration in the concrete, C0 is the initial concentration of the coating layer, t is the placement time of the reinforced concrete after coating, the sulfite effluent coefficient K is 0.274% / month, the distance x from the sampling point to the concrete surface is 25mm, and the nitrite diffusion coefficient D is 33mm 2 / moon.

[0044] Embodiment 4: This embodiment provides a construction method for a corrosion-resistant reinforced concrete structure, comprising the following steps: (1) Build the steel skeleton, clean the mold, apply the release agent, and place the steel skeleton into the mold; (2) Put silicate cement, fine aggregate, coarse aggregate, calcium chloride, water reducer and water into a mixer and mix them. The strength grade of silicate cement is 42.5 and the addition amount is 280 kg / m 3 The fine aggregate is river sand with a fineness modulus of 2.8, and the addition amount is 750 kg / m 3 The coarse aggregate is crushed stone with a maximum particle size of 20 mm and an addition amount of 1000 kg / m 3 , the water is tap water, the addition amount is 112 kg / m3 , calcium chloride addition amount is 0.5 kg / m 3 The water reducer is a carboxylic acid water reducer, and the addition amount is 5.0 kg / m 3 , the mixing time is 4h, so that all the raw materials are fully mixed together to obtain concrete, the air content of the concrete is 6%, and the water-cement ratio is 0.4; (3) Pour concrete into the mold and vibrate it with a vibrator to ensure that the concrete is dense and free of bubbles and voids. Allow it to stand for molding and remove it from the mold after 1 day of molding and curing to obtain a reinforced concrete prefabricated part. (4) Apply anticorrosive agent to both ends of the reinforced concrete prefabricated parts to prevent the ends of the steel bars from being exposed to the air and causing corrosion. Then wrap the surface of the reinforced concrete prefabricated parts with a waterproof layer. The waterproof layer can be a plastic film or other waterproof and airtight materials to slow down the evaporation rate of water on the concrete surface, so that the hydration reaction can proceed fully and prevent the concrete surface from being eroded and damaged by the outside. (5) The reinforced concrete prefabricated parts wrapped with the waterproof layer are placed in a curing room for closed curing for 28 days. The temperature in the curing room is 20°C and the humidity is 95%. The reinforced concrete prefabricated parts after closed curing are placed in a high temperature and high humidity curing box for alternating curing. The alternating curing is a cycle curing of 49 hours of high temperature and high humidity curing and 23 hours of low temperature dry curing. The cycle is repeated 30 times. During the high temperature and high humidity curing, the temperature in the high temperature and high humidity curing box is 61°C and the humidity is 97%. The cement particles that are not completely hydrated in the concrete are further hydrated, thereby enhancing the strength of the concrete. During the low temperature dry curing, the temperature in the high temperature and high humidity curing box is 21°C and the humidity is 41%, which is conducive to the slow evaporation of the water in the concrete and the optimization of the pore structure, thereby enhancing the durability and crack resistance of the concrete. After alternating curing, the reinforced concrete components are obtained and put into use at the seaside. (6) After 180 days of use, reinforced concrete components shall be subjected to rust prevention maintenance. Pre-treatment shall be carried out on the surface. Cement mortar shall be used to repair obvious defects such as honeycombs and exposed stones. Surface debris and loose attachments shall be removed with a steel spatula. Oil stains shall be removed with appropriate solvents such as acetone. Finally, the concrete surface shall be rinsed with deionized water. The concrete surface shall be polished with sandpaper. A nitrite-based rust inhibitor shall be prepared into a 70% concentration of nitrite-based rust inhibitor aqueous solution. The polished surface shall be moistened to form a layer of water film, which is conducive to the subsequent penetration of nitrite ions. The nitrite-based rust inhibitor aqueous solution shall be applied to the pre-treated reinforced concrete component surface in multiple times, 25 ml each time. Each application shall be carried out 5 hours after the previous application has dried. The total amount of application is 2.63 kg / m 3 ; The above-mentioned nitrite-type rust inhibitor is a composition of sodium nitrite and benzotriazole, wherein the weight ratio of sodium nitrite to benzotriazole is 3:1; (7) After the painting is completed, it is allowed to stand for t1 time before re-painting. The pretreatment and rust remover used during re-painting are the same as those used during painting. A 70% concentration of nitrite type rust inhibitor aqueous solution is re-painted on the surface of the reinforced concrete component in multiple times, 50 ml each time, and the total amount of re-painting is 1 / 3 of the total amount of painting, thus obtaining a corrosion-resistant reinforced concrete structure; t1 is the time when the nitrite ion concentration at 25 mm from the surface reaches the maximum value. The nitrite ion concentration is calculated by the following formula: ; in is the nitrite ion concentration, is the initial nitrite ion concentration in the concrete, C0 is the initial concentration of the coating layer, t is the placement time of the reinforced concrete after coating, the sulfite effluent coefficient K is 0.274% / month, the distance x from the sampling point to the concrete surface is 25mm, and the nitrite diffusion coefficient D is 33mm 2 / moon.

[0045] Comparative Example 1: This comparative example proposes a construction method for a corrosion-resistant reinforced concrete structure, which differs from Example 1 in the curing process. The curing process of this comparative example is: put the reinforced concrete prefabricated parts wrapped with a waterproof layer into a curing room for closed curing for 28 days, the temperature in the curing room is 20°C, and the humidity is 95%, and the reinforced concrete components are obtained and put into use at the seaside. After the reinforced concrete components are put into use for 180 days, the rust-proofing maintenance process consistent with Example 1 is performed on them to obtain a corrosion-resistant reinforced concrete structure.

[0046] Comparative Example 2: A construction method for corrosion-resistant reinforced concrete structure is proposed in this comparative example. The difference from Example 1 lies in the rust prevention and maintenance process. The rust prevention and maintenance process of this comparative example is as follows: After the reinforced concrete components are put into use for 180 days, they are subjected to rust prevention and maintenance. The surface is pretreated, and obvious defects such as honeycombs and exposed stones are repaired with cement mortar. Surface debris and loose attachments are removed with a steel spatula. Oil stains are removed with appropriate solvents such as acetone. Finally, the surface is rinsed with deionized water, and the concrete surface is polished with sandpaper. The nitrite type rust inhibitor is prepared into a 70% concentration of nitrite type rust inhibitor aqueous solution, and the polished surface is wetted to form a layer of water film on the polished surface, which is conducive to the penetration of nitrite ions. The nitrite type rust inhibitor aqueous solution is applied to the pretreated reinforced concrete component surface in multiple times, 25 ml each time, and each application is repeated for 4 hours after the previous application surface is dry. The total amount of application is 1.75 kg / m 3The above-mentioned nitrite type rust inhibitor is a composition of sodium nitrite and benzotriazole, wherein the weight ratio of sodium nitrite to benzotriazole is 1:1. Re-brushing is carried out after 9 months. The pretreatment and rust remover used during re-brushing are the same as those used during painting. A 70% concentration of nitrite type rust inhibitor aqueous solution is re-brushed on the surface of reinforced concrete components in multiple times, 25 ml each time, and the total amount of re-brushing is 1 / 2 of the total amount of painting, to obtain a corrosion-resistant reinforced concrete structure.

[0047] Comparative Example 3: This comparative example proposes a construction method for corrosion-resistant reinforced concrete structure. The difference from Example 1 is that the rust inhibitor used in this comparative example is sodium nitrite, and it is prepared into a 70% sodium nitrite aqueous solution for painting and re-brushing.

[0048] Comparative Example 4: This comparative example proposes a construction method for a corrosion-resistant reinforced concrete structure. The difference from Example 1 is that the rust inhibitor used in this comparative example is benzotriazole, which is prepared into a saturated benzotriazole aqueous solution for painting and re-brushing.

[0049] Comparative Example 5: This comparative example proposes a construction method for corrosion-resistant reinforced concrete structure. The difference from Example 1 is that the total amount of coating in this comparative example is 1.5 kg / m 3 .

[0050] Comparative Example 6: This comparative example proposes a construction method for corrosion-resistant reinforced concrete structure. The difference from Example 1 is that the total amount of coating in this comparative example is 3.0 kg / m 3 .

[0051] Test Example 1: The corrosion resistance of the corrosion-resistant reinforced concrete structures prepared in Examples 1-2 and Comparative Examples 1-3 was tested, and the following experiments were conducted: (1) According to ASTM C876-22b "Standard Test Method for Corrosion Potential of Uncoated Steel in Concrete", the corrosion state of the steel bar is evaluated by measuring the potential difference reflected by the system formed by the steel bar, concrete and the reference electrode on the concrete surface. The test is carried out using a saturated copper sulfate solution electrode. The test results are shown in Table 2. The evaluation standards are as follows: E>-200mV will not corrode with a probability of more than 90%, -200mV>E>-350mV Unsure, E<-350mV will corrode with a probability greater 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 3. 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 3. 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%.

[0052] Table 2 Natural potential values ​​of steel bars ; From Table 2, we can see that: (1) As time goes by, the potential values ​​of Examples 1 and 2 change slowly and are both greater than -200 mV, indicating that the corrosion-resistant reinforced concrete structure prepared by the present invention has a good rust-proof effect and high protection durability; (2) Comparing Example 1 with Comparative Example 1, the potential of Comparative Example 1 has an obvious growth trend, and it is lower than -350mV from 7 months, indicating that its steel bars begin to corrode and continue to intensify, proving that the alternating curing process can improve the corrosion resistance of reinforced concrete. The reason is that high temperature and high humidity curing allows the cement particles that are not completely hydrated inside the concrete to further hydrate, thereby enhancing the strength of the concrete. Low temperature drying curing helps the slow evaporation of water inside the concrete and the optimization of the pore structure, thereby enhancing the durability and crack resistance of the concrete. By alternating between high temperature and high humidity and low temperature drying, the stress inside the concrete can be released and balanced, reducing the internal cracks caused by temperature changes, thereby reducing the invasion channels of corrosive media. At the same time, alternating curing can simulate the temperature and humidity changes that concrete may encounter in the actual use environment, allowing it to gradually adapt to such changes and improve its stability and durability in complex environments. (3) Comparing Example 1 with Comparative Example 2, the potential of Comparative Example 2 has an obvious growth trend, and has been lower than -200mV since May, indicating that its steel bars may be corroded. It is proved that brushing the rust inhibitor after the nitrate ion concentration reaches the maximum value can improve the corrosion resistance of reinforced concrete. The reason is that nitrite ions in the concrete tend to rise first and then fall. Brushing after the nitrite ion concentration reaches the maximum value can replenish the nitrite ions reduced by natural consumption or reaction in time, maintain the effective concentration of nitrite ions in the concrete, and at the same time, give nitrite ions sufficient time to react with the steel bar surface, thereby extending the protective action time of the rust inhibitor, enhancing the overall corrosion resistance of the reinforced concrete structure, effectively slowing down the corrosion rate of the steel bars, and improving the durability and safety of the structure. (4) Comparing Example 1 with Comparative Examples 3 and 4, the potential growth trend of Comparative Examples 3 and 4 is obvious, indicating that the steel bars begin to corrode and the corrosion is getting worse. This proves that the combination of sodium nitrite and benzotriazole has a better rust-inhibiting effect than sodium nitrite. The reason is that nitrite ions form a protective film of Fe2O3 on the surface of the steel bars, which hinders the anodic dissolution of iron. The adsorption of nitrite ions on the iron surface reduces the free energy of the system, making passivation easier and providing anodic protection for the steel bars. Benzotriazole reacts with the steel bars to form a multilayer protective film Fe n (Cl) p (BTA) m It tightly covers the surface of the steel bar, preventing the entry of chloride ions, and providing cathodic protection for the steel bar. Under the synergistic effect of the two, it provides both anode and cathode protection for the steel bar, forming a dense protective film on the surface of the steel bar, effectively protecting the steel bar and preventing rust for a long time. (5) Comparing Example 1 with Comparative Examples 5 and 6, the potential growth trend of Comparative Example 5 is obvious, while the potential growth trend of Comparative Example 6 is gentle, which proves that the total amount of coating is 1.75~2.63 kg / m 3 When the amount of additional paint is 1 / 3 to 1 / 2 of the amount of paint applied, it can effectively prevent rust. When the total amount of paint applied is less than 1.75 kg / m 3 When the total amount of paint is greater than 2.63 kg / m 3 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.

[0053] Table 3 Steel bar corrosion area rate and weight loss rate ; It can be seen from Table 3 that the corrosion area rate and weight loss rate of Examples 1 and 2 are much smaller than those of Comparative Examples 1-5. The corrosion-resistant reinforced concrete structure prepared by the present invention has a good rust-proof effect and high protection durability.

[0054] The raw materials and equipment used in the present invention, unless otherwise specified, are all commonly used raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are all conventional methods in the art.

[0055] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A construction method for a corrosion-resistant reinforced concrete structure, Its characteristics are: The following steps are involved: 1) Mixing silicate cement, fine aggregate, coarse aggregate, calcium chloride, water reducing agent and water into concrete to prepare reinforced concrete precast parts; 2) Apply antiseptic to both ends of the reinforced concrete prefabricated parts, cover the surface with a waterproof layer, and perform closed curing at 20-22°C for 26-28 days, then perform alternating curing to obtain reinforced concrete components and put them into use; the alternating curing process is 47-49 hours of high temperature and high humidity curing and 23-25 ​​hours of low temperature and dry curing, which are performed alternately for 30 times, wherein the high temperature and high humidity curing temperature is 59-61°C and the humidity is 97-98%, and the low temperature and dry curing temperature is 19-21°C and the humidity is 39-41%; 3) After the reinforced concrete components are put into use for 180-270 days, apply nitrite-type rust inhibitor on their surface and place them for t 1 After a certain time, apply additional paint, the amount of which is 1 / 3 to 1 / 2 of the amount of paint, and the corrosion-resistant reinforced concrete structure is obtained; t 1 is the time when the nitrite ion concentration at 25 mm from the surface reaches the maximum value, and the nitrite ion concentration is calculated by the following formula: ； in is the nitrite ion concentration, is the initial nitrite ion concentration in concrete, C 0 is the initial concentration of the coating layer, t is the placement time of the reinforced concrete after coating, the sulfite effluent coefficient K is 0.274% / month, the distance x between the sampling point and the concrete surface is 25mm, and the nitrite diffusion coefficient D is 33mm 2 / moon.

2. A construction method for a corrosion-resistant reinforced concrete structure according to claim 1, Its characteristics are: In step 1), Cl in the reinforced concrete prefabricated part - Content is 0.1~0.65 kg / m 3 , the gas content is 4~6%.

3. A construction method for a corrosion-resistant reinforced concrete structure according to claim 1, Its characteristics are: In step 3), the nitrite type rust inhibitor is a rust inhibitor composition comprising an anodic rust inhibitor component A and a cathodic rust inhibitor component B, wherein the anodic rust inhibitor component A is sodium nitrite and the cathodic rust inhibitor component B is benzotriazole, and the weight ratio of the two is 1-9:3, and the coating amount of the nitrite type rust inhibitor is 1.75-2.63 kg / m 3 .

4. A construction method for a corrosion-resistant reinforced concrete structure according to claim 1, 2 or 3, Its characteristics are: In step 1), the water-cement ratio of the reinforced concrete prefabricated part is 0.3-0.

5.

5. A construction method for a corrosion-resistant reinforced concrete structure according to claim 1, 2 or 3, Its characteristics are: In step 1), the strength grade of the silicate cement is 42.5, and the addition amount is 280-320 kg / m 3 The fine aggregate is river sand with a fineness modulus of 2.6-2.8, and the addition amount is 750-770 kg / m 3 The coarse aggregate is crushed stone with a particle size of 5 to 20 mm and the addition amount is 1000 to 1100 kg / m 3 The water reducer is a carboxylic acid water reducer, and the addition amount is 4.5~5.0 kg / m 3 .

6. A construction method for a corrosion-resistant reinforced concrete structure according to claim 1, 2 or 3, Its characteristics are: In step 2), the preservative is epoxy resin.

7. A construction method for a corrosion-resistant reinforced concrete structure according to claim 1, 2 or 3, Its characteristics are: In step 3), the specific painting process is as follows: pre-treat the surface of the reinforced concrete component, and apply the nitrite type rust inhibitor to the pre-treated surface of the reinforced concrete component in multiple times, and each painting is performed after a period of time after the previous painting surface is dry.

8. A construction method for a corrosion-resistant reinforced concrete structure according to claim 7, Its characteristics are: In step 3), the pretreatment is to repair, clean and sand the surface of the reinforced concrete component.

9. A construction method for a corrosion-resistant reinforced concrete structure according to claim 7, Its characteristics are: In step 3), apply 25-50 ml each time.

10. A construction method for a corrosion-resistant reinforced concrete structure according to claim 7, Its characteristics are: In step 3), each application should be done after the previously applied surface has dried for 3 to 5 hours.

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