Corrosion-resistant mortar coating for rapid repair of concrete structure, and preparation method therefor and use thereof

Abstract

Disclosed in the present application are a corrosion-resistant mortar coating for the rapid repair of a concrete structure, and a preparation method therefor and the use thereof. The corrosion-resistant mortar coating is composed of cement, a superhydrophobic oyster shell powder, calcium formate and water, wherein the superhydrophobic oyster shell powder is a stearic-acid-modified oyster shell powder. The superhydrophobic mortar coating capable of realizing rapid setting and hardening provided in the present application has a good superhydrophobicity, corrosion resistance and self-cleaning performance, and can effectively improve the durability of a cement-based material.

Description

A corrosion-resistant mortar coating for quickly repairing concrete structures, and its preparation method and application

[0001] This application claims priority to a Chinese patent application filed with the Patent Office of China on June 15, 2023, with application number CN202310709432.9 and invention name “A method for preparing corrosion-resistant mortar coating for rapid repair of concrete structures”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of marine structural engineering, and in particular to a corrosion-resistant mortar coating for quickly repairing concrete structures, and a preparation method and application thereof. Background Art

[0003] Cement-based materials, thanks to their low cost and simple production process, have become a primary building material for marine structural engineering. However, the inherent hydrophilicity of cement-based materials allows water from the marine environment to easily penetrate the material. Corrosive ions in seawater penetrate the material through the water, causing corrosion of the internal reinforcement. This in turn leads to a decrease in the structural bearing capacity due to insufficient durability before the structure reaches its designed service life. To prevent further degradation of structural performance, emergency repairs of damaged structures are necessary. For emergency repairs, cement-based materials must exhibit good early strength. Therefore, early-strength agents are often added to the cement-based materials used for repairs to accelerate cement hydration and improve the early strength of the cement-based material. However, the use of early-strength agents can lead to increased porosity in the cement-based material over time. This increased porosity provides a pathway for the entry of water and corrosive ions, significantly reducing the material's corrosion resistance.

[0004] Research on hydrophobic properties offers a new and viable solution for corrosion protection of cement-based materials. Low-surface-energy hydrophobic materials can impart hydrophobicity to cement-based materials, effectively preventing water penetration and further improving the material's corrosion resistance. However, currently used hydrophobic materials often contain fluorine or are expensive. These materials impose an increased environmental burden, limiting their widespread use in cement-based materials.

[0005] A Chinese invention patent application, publication number CN110408292A, discloses a concrete anticorrosive coating and its manufacturing method. This invention utilizes amorphous silica, amorphous aluminum oxide, polymethyl acrylate, polyacrylamide, sodium dodecylsulfonate, ammonium persulfate, and deionized water to create a primer, and nano-aluminum oxide, nano-silicon oxide, isopropyl alcohol, filler, methyltrimethoxysilane, polydimethylsiloxane, gamma-glycidyloxypropyltrimethoxysilane, and acetic acid to create a topcoat. The coating utilizes a large amount of polymer materials, resulting in complex operation and high costs, making it unsuitable for large-scale use. Flammable, explosive, and corrosive reagents are used during the preparation process, making it difficult to use in actual projects. Furthermore, because the concrete and coating are completely sealed, evaporation of excess free water in the concrete pores causes expansion between the concrete and coating, leading to coating shedding and, consequently, loss of the coating's protective properties.

[0006] Summary of the Invention

[0007] Based on the above technical problems, the present application proposes a corrosion-resistant mortar coating for quickly repairing concrete structures, as well as a preparation method and application thereof.

[0008] The technical solutions adopted in this application are:

[0009] The invention provides a corrosion-resistant mortar coating for quickly repairing concrete structures. The mortar coating consists of cement, super-hydrophobic oyster shell powder, calcium formate and water; the super-hydrophobic oyster shell powder is stearic acid-modified oyster shell powder.

[0010] Preferably, the mass ratio of the cement to the super-hydrophobic oyster shell powder is 1:0.8-1.2.

[0011] Preferably, the mass ratio of the calcium formate to water is 0.02-0.05:1; the mass ratio of the water to cement is 0.5-0.6:1.

[0012] The present invention also provides a method for preparing a corrosion-resistant mortar coating for quickly repairing concrete structures, comprising the following steps:

[0013] a. Select cement, oyster shell powder, stearic acid, calcium formate, anhydrous ethanol and water as raw materials;

[0014] b. Mixing stearic acid and anhydrous ethanol, stirring evenly to obtain a modified solution with low surface energy;

[0015] c. adding oyster shell powder to the modified solution with low surface energy obtained in step b, stirring at room temperature to obtain a premix;

[0016] The premix is ​​placed in a vacuum drying oven and dried to obtain super-hydrophobic oyster shell powder.

[0017] d. mixing cement and the super-hydrophobic oyster shell powder obtained in step c, stirring to obtain a mixture;

[0018] e. Mixing calcium formate and water to obtain a mixed solution, then adding the mixed solution to the mixture obtained in step d, stirring, to obtain a corrosion-resistant mortar coating.

[0019] Preferably, in step b: the ratio of the mass of the stearic acid to the volume of anhydrous ethanol is 5-7g:100-150ml.

[0020] Preferably, in step b: the stirring is magnetic stirring, the stirring speed is 1000-1200 r / min, the stirring time is 5-7 minutes, and the stirring is carried out at 40-45°C.

[0021] Preferably, in step c: the mass ratio of the amount of the oyster shell powder to the amount of stearic acid is 80-100:5-7.

[0022] Preferably, in step c: when preparing the premix, the stirring speed is 1200-1500 r / min, and the stirring time is 1-1.5 hours.

[0023] Preferably, in step c: the drying temperature is 70-80° C., and the drying time is 5-6 hours.

[0024] Preferably, in step d: the stirring time is 1-3 minutes.

[0025] Preferably, in step e: the stirring time is 30-45 minutes.

[0026] Preferably, the water contact angle of the surface of the superhydrophobic oyster shell powder is 153.2°.

[0027] Preferably, the water contact angle of the coating surface formed by the corrosion-resistant mortar coating is 152.5°.

[0028] The present invention also provides the use of the corrosion-resistant mortar coating described in the above technical solution or the corrosion-resistant mortar coating prepared by the preparation method described in the above technical solution in the rapid repair of concrete structures.

[0029] Preferably, the application is: spraying or brushing the corrosion-resistant mortar coating on the surface of a concrete structure to quickly repair the concrete structure.

[0030] The beneficial technical effects of this application are:

[0031] 1. The present application prepares a corrosion-resistant mortar coating with good early strength, which can be used for coastal embankments, bridge pier structures, etc. damaged by long-term seawater erosion, and plays a role in rapid repair. The present application uses environmentally friendly and non-toxic stearic acid and oyster shell powder to prepare oyster shell powder particles with super-hydrophobic properties, and then uses the prepared super-hydrophobic oyster shell powder as a hydrophobic medium and calcium formate as an early strength agent to prepare a super-hydrophobic mortar coating that can quickly coagulate and harden. The preparation method of the present application utilizes the rapid coagulation and hardening effect of calcium formate and the corrosion resistance of super-hydrophobic oyster shell powder.

[0032] 2. The oyster shell powder used in this application is a common aquaculture byproduct, with increasing production and difficult processing. The unique ribbed morphology of oyster shells facilitates the creation of a superhydrophobic surface roughness. The preparation process also enables waste recycling and improves the corrosion resistance of cement-based materials, achieving structural repair through a green and environmentally friendly method.

[0033] 3. The early strength agent calcium formate used in this application does not contain chlorine, which effectively avoids the occurrence of internal corrosion of the material.

[0034] 4. This application uses stearic acid as a modified low surface energy substance, which is non-toxic, non-polluting and has good stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG1 is a flow chart of a method for preparing a corrosion-resistant mortar coating for rapid repair of concrete structures according to the present invention;

[0036] FIG2 is a scanning electron microscope image of the super-hydrophobic oyster shell powder prepared in this application;

[0037] FIG3 shows the wettability behavior and water contact angle of a water droplet on the surface of the super-hydrophobic oyster shell powder prepared in this application;

[0038] FIG4 is a Fourier transform infrared spectra of ordinary oyster shell powder and the super-hydrophobic oyster shell powder prepared in this application;

[0039] FIG5 shows the wettability behavior and water contact angle of a water droplet on the surface of the corrosion-resistant mortar coating prepared in this application;

[0040] FIG6 shows the thermogravimetric analysis results of ordinary mortar cured for 7 days and the corrosion-resistant mortar coating prepared in this application;

[0041] FIG7 is a diagram showing the anti-corrosion mechanism of the corrosion-resistant mortar coating prepared in this application. DETAILED DESCRIPTION

[0042] It has been found that marine structures such as coastal dams and bridge pier structures are subject to the erosion of seawater all year round. Due to the erosion of materials by dryness and wetness, weathering and various corrosive ions, the structures are extremely vulnerable to damage. Based on this, the present application creatively uses oyster shell powder, a by-product of aquatic products. Its unique prism-like morphology is conducive to constructing the roughness of super-hydrophobic surfaces, and utilizes the hydrophobicity of stearic acid and the rapid coagulation and hardening performance of calcium formate to prepare a mortar coating that can be used for rapid repair of marine concrete structures. The mortar coating of the present application can play a role in waste recycling and extending the service life of concrete structures. The oyster shell powder used is a common by-product in aquaculture, with large output, which can effectively reduce costs and has significant environmental benefits. The modifier stearic acid and early strength agent calcium formate used are non-toxic and stable, with low cost, and are conducive to large-scale construction, and the coating can quickly coagulate and harden so as to efficiently achieve protection of the structure. In addition, the early strength agent used in the present application does not contain chlorine, which is conducive to the long-term protection of the coating to the structure. The corrosion-resistant mortar coating prepared in the present application has good super-hydrophobicity, corrosion resistance and self-cleaning properties, and can effectively improve the durability of cement-based materials.

[0043] The present application will be further described below with reference to specific embodiments.

[0044] Example 1

[0045] A method for preparing a corrosion-resistant mortar coating for quickly repairing concrete structures comprises the following steps:

[0046] a. Select cement, oyster shell powder, stearic acid, calcium formate, anhydrous ethanol and water as raw materials;

[0047] b) Weigh 7 g of stearic acid and mix with 150 ml of anhydrous ethanol. Use a magnetic stirrer to stir at 1200 rpm and 40°C for 5 minutes to obtain a modified solution with low surface energy.

[0048] c. Weigh 100 g of oyster shell powder and add it to the modified solution with low surface energy prepared in step b. Stir at room temperature at a speed of 1200 r / min for 1 hour to obtain a premix; place the premix in a vacuum drying oven at a temperature of 70° C. and dry it for 5 hours to obtain superhydrophobic oyster shell powder;

[0049] d. Weigh cement and the super-hydrophobic oyster shell powder prepared in step c in a mass ratio of 1:1, mix and stir for 1 minute to obtain a mixture;

[0050] e. Mixing calcium formate and water in a mass ratio of 0.02:1 and a ratio of water to the cement in step d of 0.5:1 to obtain a mixed solution; then adding the mixed solution to the mixture obtained in step d, stirring for 30 minutes, and obtaining a fresh corrosion-resistant mortar coating;

[0051] f. Spraying or brushing the corrosion-resistant mortar coating prepared in step e on the surface of the concrete structure can quickly repair the concrete structure.

[0052] Example 2

[0053] A method for preparing a corrosion-resistant mortar coating for quickly repairing concrete structures comprises the following steps:

[0054] a. Select cement, oyster shell powder, stearic acid, calcium formate, anhydrous ethanol and water as raw materials;

[0055] b) Weigh 7 g of stearic acid and 120 ml of anhydrous ethanol, mix them, and use a magnetic stirrer to stir at 1000 rpm and 45°C for 7 minutes to obtain a modified solution with low surface energy;

[0056] c. Weigh 90 g of oyster shell powder and add it to the modified solution with low surface energy prepared in step b. Stir at room temperature at a speed of 1200 r / min for 1.5 hours to obtain a premix; place the premix in a vacuum drying oven at a temperature of 80° C. and dry it for 5 hours to obtain superhydrophobic oyster shell powder;

[0057] d. Weigh cement and the super-hydrophobic oyster shell powder prepared in step c in a mass ratio of 1:0.8, mix and stir for 3 minutes to obtain a mixture;

[0058] e. Mixing calcium formate and water in a mass ratio of 0.02:1 and a mass ratio of water to the cement in step d of 0.55:1 to obtain a mixed solution; then adding the mixed solution to the mixture obtained in step d and stirring for 40 minutes to obtain a fresh corrosion-resistant mortar coating;

[0059] f. Spraying or brushing the corrosion-resistant mortar coating prepared in step e on the surface of the concrete structure can quickly repair the concrete structure.

[0060] Example 3

[0061] A method for preparing a corrosion-resistant mortar coating for quickly repairing concrete structures comprises the following steps:

[0062] a. Select cement, oyster shell powder, stearic acid, calcium formate, anhydrous ethanol and water as raw materials;

[0063] b. Weigh 5 g of stearic acid and mix with 100 ml of anhydrous ethanol. Use a magnetic stirrer to stir at 1200 r / min and 40°C for 6 minutes to obtain a modified solution with low surface energy.

[0064] c. Weigh 80 g of oyster shell powder and add it to the modified solution with low surface energy prepared in step b. Stir the mixture at 1500 rpm for 1.2 hours at room temperature to obtain a premix. Place the premix in a vacuum drying oven at 70° C. and dry it for 5 hours to obtain super-hydrophobic oyster shell powder.

[0065] d. Weigh cement and the super-hydrophobic oyster shell powder prepared in step c in a mass ratio of 1:1.2, mix and stir for 3 minutes to obtain a mixture;

[0066] e. Mixing calcium formate and water in a mass ratio of 0.05:1 and a mass ratio of water to the cement in step d of 0.6:1 to obtain a mixed solution; then adding the mixed solution to the mixture obtained in step d and stirring for 45 minutes to obtain a fresh corrosion-resistant mortar coating;

[0067] f. Spraying or brushing the corrosion-resistant mortar coating prepared in step e on the surface of the concrete structure can quickly repair the concrete structure.

[0068] Example 4

[0069] A method for preparing a corrosion-resistant mortar coating for quickly repairing concrete structures comprises the following steps:

[0070] a. Select cement, oyster shell powder, stearic acid, calcium formate, anhydrous ethanol and water as raw materials;

[0071] b) Weigh 6 g of stearic acid and mix with 150 ml of anhydrous ethanol. Use a magnetic stirrer to stir at 1100 rpm and 40°C for 7 minutes to obtain a modified solution with low surface energy.

[0072] c. Weigh 100 g of oyster shell powder and add it to the modified solution with low surface energy prepared in step b. Stir at room temperature at a speed of 1500 r / min for 1 hour to obtain a premix; place the premix in a vacuum drying oven at a temperature of 70° C. and dry it for 6 hours to obtain superhydrophobic oyster shell powder;

[0073] d. Weigh cement and the super-hydrophobic oyster shell powder prepared in step c in a mass ratio of 1:1, mix and stir for 3 minutes to obtain a mixture;

[0074] e. Mixing calcium formate and water in a mass ratio of 0.03:1 and a mass ratio of water to the cement in step d of 0.5:1 to obtain a mixed solution; then adding the mixed solution to the mixture obtained in step d and stirring for 30 minutes to obtain a fresh corrosion-resistant mortar coating;

[0075] f. Spraying or brushing the corrosion-resistant mortar coating prepared in step e on the surface of the concrete structure can quickly repair the concrete structure.

[0076] If it is necessary to verify the performance of the corrosion-resistant mortar coating prepared in the above embodiment, the following subsequent treatments may be performed on it:

[0077] Pour the freshly mixed cement mortar into the corresponding mold and vibrate to remove any bubbles. Apply a release agent to the mold in advance. De-mould after 24 hours and place in a standard environment of 20°C and 95% ± 1% for curing.

[0078] Figure 1 is a flow chart of the method for preparing the corrosion-resistant mortar coating for rapid repair of concrete structures in the present application. Figure 2 is a scanning electron microscope image of the super-hydrophobic oyster shell powder prepared in the present application at a magnification of 5000×. It can be clearly seen from the figure that the oyster shell powder is an irregular prism-like structure. When a large amount of oyster shell powder is mixed in a cement mixture, the oyster shell powders are stacked and crossed with each other, which is conducive to constructing the roughness of the super-hydrophobic surface. Figure 3 shows the wettability behavior and water contact angle of water droplets on the surface of the super-hydrophobic oyster shell powder prepared in the present application, where 11 is a water droplet and 12 is the prepared super-hydrophobic oyster shell powder; it can be observed from the figure that the contact angle of water droplets on the surface of the super-hydrophobic oyster shell powder can reach 153.2°. Among them, in order to more clearly observe the wettability behavior of water droplets on the surface of the super-hydrophobic oyster shell powder, the water droplets are stained with methylene blue. Figure 4 is the Fourier infrared spectra of ordinary oyster shell powder and the super-hydrophobic oyster shell powder prepared in this application. Two new absorption peaks appear in the Fourier infrared spectrum of the super-hydrophobic oyster shell powder, which are located at 2916 cm -1 The methylene and 2849cm -1 The methyl groups in the stearic acid indicate that the hydrophobic groups in the stearic acid have been successfully grafted onto the surface of the oyster shell powder. Figure 5 shows the wettability behavior and water contact angle of water droplets on the surface of the corrosion-resistant mortar coating prepared in this application, where 13 is a water droplet and 14 is the prepared corrosion-resistant mortar coating. It can be seen from the figure that the water droplets did not penetrate into the mortar coating, but were supported on the surface and approached a spherical shape. The water contact angle reached 152.5°, indicating that the prepared mortar coating achieved superhydrophobicity and exhibited a good water-repellent effect.

[0079] In addition, in order to achieve the purpose of quickly repairing concrete structures, it is necessary to require the mortar coating to have good early strength. Figure 6 shows the thermogravimetric analysis results of ordinary mortar cured for 7 days and the corrosion-resistant mortar coating prepared in this application. It can be seen from the figure that the mass of the mortar decreases with increasing temperature, and the mass loss at different stages corresponds to the content of different hydration products in the mortar. The results show that the mass loss of the coating in the temperature range of 30°C to 250°C is higher than that of ordinary mortar, which means that the content of hydrated calcium silicate and calcium aluminate in the coating is higher than that of ordinary mortar. In addition, it can be found from the first-order derivative curve of the thermogravimetric analysis curve that the mortar coating presents a larger peak in the temperature range of 30°C to 250°C. The results show that the hydration degree of the coating is higher than that of ordinary mortar when it is cured for 7 days, indicating that the coating has a faster early hydration rate.

[0080] Figure 7 is a diagram illustrating the anti-corrosion mechanism of the corrosion-resistant mortar coating prepared in this application. As can be seen from the figure, the pores in the rough structure of the corrosion-resistant mortar coating surface can trap air and form an air layer. This air layer can block water and corrosive ions from the surface, making it difficult for them to penetrate into the material and cause corrosion.

[0081] In summary, the present application uses environmentally friendly and non-toxic stearic acid and oyster shell powder to prepare oyster shell powder particles with super-hydrophobic properties, and then uses the prepared super-hydrophobic oyster shell powder as a hydrophobic medium and calcium formate as an early strength agent to prepare a super-hydrophobic mortar coating that can quickly coagulate and harden. The corrosion-resistant mortar coating prepared in this application has good super-hydrophobicity, corrosion resistance and self-cleaning performance, which can effectively improve the durability of cement-based materials.

[0082] Although the above embodiment provides a detailed description of the present application, it is only a part of the embodiments of the present application rather than all the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present application.

Claims

1. A corrosion-resistant mortar coating for rapid repair of concrete structures, characterized in that: The invention is composed of cement, super-hydrophobic oyster shell powder, calcium formate and water; the super-hydrophobic oyster shell powder is stearic acid-modified oyster shell powder.

2. The corrosion-resistant mortar coating according to claim 1, characterized in that: The mass ratio of the cement to the super-hydrophobic oyster shell powder is 1:0.8-1.

2.

3. The corrosion-resistant mortar coating according to claim 1 or 2, characterized in that: The mass ratio of the calcium formate to water is 0.02-0.05:1; the mass ratio of the water to cement is 0.5-0.6:

1.

4. A method for preparing a corrosion-resistant mortar coating for rapid repair of concrete structures, characterized in that: The following steps are involved: a Select cement, oyster shell powder, stearic acid, calcium formate, anhydrous ethanol and water as raw materials; b. Mixing stearic acid and anhydrous ethanol, stirring evenly, to obtain a modified solution with low surface energy; c. adding oyster shell powder to the modified solution obtained in step b, stirring at room temperature to obtain a premix; placing the premix in a vacuum drying oven and drying to obtain super-hydrophobic oyster shell powder; d. mixing cement and the super-hydrophobic oyster shell powder obtained in step c, stirring to obtain a mixture; e. Mixing calcium formate and water to obtain a mixed solution, and then adding the mixed solution to the mixture obtained in step d, stirring, to obtain a corrosion-resistant mortar coating.

5. The preparation method according to claim 4, characterized in that: In step b: the ratio of the mass of the stearic acid to the volume of anhydrous ethanol is 5-7g:100-150ml.

6. The preparation method according to claim 4, characterized in that: In step b: the stirring is magnetic stirring, the stirring speed is 1000-1200r / min, the stirring time is 5-7 minutes, and the stirring is carried out at 40-45°C.

7. The preparation method according to claim 4, characterized in that: In step c: the mass ratio of the oyster shell powder to stearic acid is 80-100:5-7.

8. The preparation method according to claim 4, characterized in that: In step c: when preparing the premix, the stirring speed is 1200-1500 r / min, and the stirring time is 1-1.5 hours.

9. The preparation method according to claim 4, characterized in that: In step c: the drying temperature is 70-80° C., and the drying time is 5-6 hours.

10. The preparation method according to claim 4, characterized in that: In step d: the stirring time is 1-3 minutes.

11. The preparation method according to claim 4, characterized in that: In step e: the stirring time is 30-45 minutes.

12. The preparation method according to claim 4, characterized in that: The water contact angle on the surface of the super-hydrophobic oyster shell powder is 153.2°.

13. The preparation method according to claim 4, characterized in that: The water contact angle of the coating surface formed by the corrosion-resistant mortar coating is 152.5°.

14. Use of the corrosion-resistant mortar coating according to any one of claims 1 to 3 or the corrosion-resistant mortar coating prepared by the preparation method according to any one of claims 4 to 13 in rapid repair of concrete structures.

15. The use according to claim 14, characterized in that: The application is: spraying or brushing the corrosion-resistant mortar coating on the surface of a concrete structure to quickly repair the concrete structure.

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