Inorganic carbonation-resistant coating, preparation method and application thereof, and inorganic carbonation-resistant coating layer

Abstract

The application provides an inorganic carbonation-preventing coating material and a preparation method and application thereof, and an inorganic carbonation-preventing coating, and relates to the technical field of concrete.The inorganic carbonation-preventing coating material provided by the application contains the following preparation raw materials in percentage by mass: 80-120 parts of steel slag, 0-4 parts of silicon carbide, 2-6 parts of water reducing agent and 30-50 parts of water.In the application, the steel slag has high carbonation reactivity, and the product after carbonation is calcium carbonate crystal and highly polymerized SiO2 gel.The CO2 diffusion rate is fast at the beginning of the carbonation reaction, a large amount of calcium carbonate is generated on the surface of the steel slag particles, after carbonation, the SiO2 gel wraps the calcium silicate in the unreacted steel slag, the calcium carbonate crystal fills between the pores of the steel slag particles, and a dense structure is formed.When the inorganic carbonation-preventing coating material is coated on the surface of a concrete base, excellent bonding effect with the base is achieved, and the effect of preventing carbonation of the concrete base is achieved.

Description

Technical Field

[0001] This invention belongs to the field of concrete technology, specifically relating to an inorganic anti-carbonation coating, its preparation method and application, and an inorganic anti-carbonation coating layer. Background Technology

[0002] Concrete durability is a crucial property, referring to its ability to resist damage in various service environments. Insufficient durability leads to concrete deterioration, significantly shortening its service life, while maintenance and repair result in substantial economic losses. To improve concrete durability and extend its lifespan, numerous studies have been conducted. Current technologies utilize coatings to treat the concrete surface, forming a protective barrier to prevent damage from corrosive ions. Organic coatings, such as polyurethane, epoxy resin, and acrylic resin, are widely used. These protect concrete from erosion by shielding it from corrosive agents and reducing water and gas penetration. However, these organic polymer coatings exhibit poor durability under ultraviolet radiation.

[0003] Inorganic coatings can solve the problem of poor durability. In the existing technology, geopolymers prepared from 90% metakaolin (MK) and 10% granulated blast furnace slag (GBFS) are usually used as raw materials for inorganic coatings. They have good durability, but geopolymers have high shrinkage and will cause cracking during use, resulting in poor adhesion. Summary of the Invention

[0004] The purpose of this invention is to provide an inorganic anti-carbonation coating, its preparation method and application, and an inorganic anti-carbonation coating. The inorganic anti-carbonation coating provided by this invention has excellent adhesion to concrete.

[0005] To achieve the objectives of this invention, the following technical solutions are provided:

[0006] An inorganic anti-carbonization coating comprises, by weight, the following raw materials: 80-120 parts steel slag, 0-4 parts silicon carbide, 2-6 parts water-reducing agent, and 30-50 parts water.

[0007] Preferably, the steel slag comprises: 30-40% CaO, 20-30% SiO2, 10-20% Al2O3, 10-20% Fe2O3, 5-10% MgO, 1-3% MnO, 0.1-0.5% Na2O, and 1-3% SO3; the particle size of the steel slag is 5-20 μm.

[0008] Preferably, the silicon carbide has a particle size of 0.5 to 1 μm.

[0009] Preferably, the water-reducing agent is a polycarboxylate superplasticizer; the water reduction rate of the water-reducing agent is 40-50%.

[0010] This invention also provides a method for preparing the inorganic anti-carbonization coating described in the above technical solution, comprising the following steps:

[0011] The raw materials for preparing the inorganic anti-carbonation coating are mixed to obtain the inorganic anti-carbonation coating.

[0012] Preferably, the mixing method is stirring; the stirring rate is 60-100 rpm, and the time is 3-5 min.

[0013] The present invention also provides the application of the inorganic anti-carbonation coating described in the above technical solution or the inorganic anti-carbonation coating prepared by the preparation method described in the above technical solution in the protection of concrete surfaces.

[0014] The present invention also provides an inorganic anti-carbonation coating, which is prepared by applying an inorganic anti-carbonation coating to the surface of a concrete substrate and then carbonizing it; the inorganic anti-carbonation coating is the inorganic anti-carbonation coating described in the above technical solution or the inorganic anti-carbonation coating prepared by the preparation method described in the above technical solution.

[0015] Preferably, the carbonization temperature is 10–25°C, the time is 1–2 days, the pressure is 0.1–0.2 bar, the relative humidity is 90–100%, and the CO2 concentration is 10–20%.

[0016] Preferably, the thickness of the inorganic carbonized coating is 0.5 to 1 mm.

[0017] This invention provides an inorganic anti-carbonation coating, comprising the following raw materials by weight: 80-120 parts steel slag, 0-4 parts silicon carbide, 2-6 parts water-reducing agent, and 30-50 parts water. In this invention, steel slag exhibits high carbonation reactivity, and its carbonation products are calcium carbonate crystals and highly polymerized SiO2 gel. The CO2 diffusion rate is rapid at the beginning of the carbonation reaction, generating a large amount of calcium carbonate on the surface of the steel slag particles. After carbonation, the SiO2 gel encapsulates the unreacted calcium silicate in the steel slag, while the calcium carbonate crystals fill the pores between the steel slag particles, forming a dense structure. When the inorganic anti-carbonation coating is applied to the surface of a concrete substrate, it exhibits excellent adhesion to the substrate and prevents carbonation of the concrete substrate. Furthermore, steel slag is a byproduct of the steelmaking process; as an inorganic anti-carbonation coating, it can consume a large amount of steel slag, which is beneficial to environmental protection. Additionally, steel slag can absorb CO2 from the air, achieving a "carbon reduction" effect. Furthermore, in this invention, silicon carbide is used as a binder, which increases the bonding strength between the inorganic anti-carbonation coating and concrete. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a picture of actual steel slag.

[0020] Figure 2 The image shows the XRD pattern of steel slag.

[0021] Figure 3 This is a photograph of the inorganic anti-carbonization coating before carbonization as described in Example 2.

[0022] Figure 4 This is a photograph of the inorganic anti-carbonization coating described in Example 2 after carbonization.

[0023] Figure 5 A carbonation depth test image of a concrete specimen coated with the inorganic anti-carbonation coating described in Example 2;

[0024] Figure 6 A graph showing the carbonation depth of a concrete specimen without any coating. Detailed Implementation

[0025] This invention provides an inorganic anti-carbonization coating, which, by mass parts, comprises the following raw materials: 80-120 parts of steel slag, 0-4 parts of silicon carbide, 2-6 parts of water-reducing agent, and 30-50 parts of water.

[0026] In this invention, unless otherwise specified, all raw materials used in the preparation are preferably commercially available products well known to those skilled in the art.

[0027] In this invention, the raw materials for preparing the inorganic anti-carbonization coating, by mass, include 80-120 parts of steel slag, preferably 90-100 parts. In this invention, the steel slag preferably comprises: 30-40% CaO, 20-30% SiO2, 10-20% Al2O3, 10-20% Fe2O3, 5-10% MgO, 1-3% MnO, 0.1-0.5% Na2O, and 1-3% SO3; more preferably, 34.25% CaO, 22.27% SiO2, 12.33% Al2O3, 15.09% Fe2O3, 9.11% MgO, 2.05% MnO, 0.38% Na2O, and 1.01% SO3. In this invention, the particle size of the steel slag is preferably 5-20 μm, more preferably 10 μm. In this invention, steel slag can absorb CO2 from the air, achieving the effect of "carbon reduction".

[0028] In this invention, the raw materials for preparing the inorganic anti-carbonation coating, based on the mass fraction of steel slag, include 0-4 parts of silicon carbide (SiC), preferably 2-3 parts. In this invention, the particle size of the silicon carbide is preferably 0.5-1 μm, more preferably 0.7-0.8 μm. In this invention, silicon carbide improves the bonding performance between the inorganic anti-carbonation coating and concrete.

[0029] In this invention, the raw materials for preparing the inorganic anti-carbonation coating, based on the mass fraction of steel slag, include 2-6 parts of a water-reducing agent, preferably 3-5 parts. In this invention, the water-reducing agent is preferably a polycarboxylate high-efficiency water-reducing agent. In this invention, the water reduction rate of the water-reducing agent is preferably 40-50%. In this invention, the water-reducing agent has the function of reducing the water-cement ratio and improving the fluidity of the slurry.

[0030] In this invention, the raw materials for preparing the inorganic anti-carbonation coating include 30-50 parts of water, preferably 40 parts, based on the mass fraction of steel slag. In this invention, the water is preferably deionized water.

[0031] This invention also provides a method for preparing the inorganic anti-carbonization coating described in the above technical solution, comprising the following steps:

[0032] The raw materials for preparing the inorganic anti-carbonation coating are mixed to obtain the inorganic anti-carbonation coating.

[0033] In this invention, the mixing method is preferably stirring. The stirring rate is preferably 60–100 rpm, more preferably 70–80 rpm; the stirring time is preferably 3–5 min, more preferably 4 min.

[0034] The present invention also provides the application of the inorganic anti-carbonation coating described in the above technical solution or the inorganic anti-carbonation coating prepared by the preparation method described in the above technical solution in the protection of concrete surfaces.

[0035] The present invention also provides an inorganic anti-carbonation coating, which is prepared by applying an inorganic anti-carbonation coating to the surface of a concrete substrate and then carbonizing it; the inorganic anti-carbonation coating is the inorganic anti-carbonation coating described in the above technical solution or the inorganic anti-carbonation coating prepared by the preparation method described in the above technical solution.

[0036] The present invention does not have any special limitation on the raw materials for preparing the concrete; any concrete well known to those skilled in the art can be used.

[0037] The present invention does not impose any special limitations on the coating method and conditions; any coating method and conditions known to those skilled in the art can be used.

[0038] In this invention, the carbonization temperature is preferably 10–25°C, more preferably 10°C; the time is preferably 1–2 days, more preferably 1 day; the pressure is preferably 0.1–0.2 bar, more preferably 0.2 bar; the CO2 concentration is preferably 10–20%, more preferably 15%; and the relative humidity (RH) is preferably 95–100%. This invention carbonizes steel slag into calcium carbonate crystals and highly polymerized SiO2 gel. At the beginning of carbonization, the CO2 diffusion rate is relatively fast, generating a large amount of carbonation products on the surface of the steel slag particles. After carbonization, the SiO2 gel encapsulates the unreacted calcium silicate in the steel slag, while the calcium carbonate crystals fill the pores between the steel slag particles, forming a dense structure. This not only gives the inorganic anti-carbonation coating excellent adhesion to concrete but also prevents concrete carbonation.

[0039] In this invention, the thickness of the inorganic carbonized coating is preferably 0.5 to 1 mm, more preferably 0.6 to 0.8 mm.

[0040] To further illustrate the present invention, the inorganic anti-carbonization coating and inorganic anti-carbonization coating provided by the present invention will be described in detail below with reference to the accompanying drawings and embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0041] The parameters for preparing the raw materials in the following embodiments and comparative examples of the present invention are shown below:

[0042] Steel slag: 34.25% CaO, 22.27% SiO2, 12.33% Al2O3, 15.09% Fe2O3, 9.11% MgO, 2.05% MnO, 0.38% Na2O and 1.01% SO3; particle size 10μm; Figure 1 The image shows a real piece of steel slag. Figure 2 The image shows the XRD pattern of steel slag.

[0043] SiC: Particle size is 0.8μm;

[0044] Polycarboxylate superplasticizer: water reduction rate of 50%;

[0045] Concrete matrix: P.Ⅱ42.5 silicate cement, fine aggregate (river sand) and water are prepared with a cement-sand ratio of 1:3 and a water-cement ratio of 0.5.

[0046] Example 1

[0047] Weigh 2g of SiC, 100g of steel slag, 40g of water and 4g of polycarboxylate superplasticizer, stir at room temperature for 5 minutes to obtain an inorganic anti-carbonation coating.

[0048] The above-mentioned inorganic anti-carbonation coating was applied to the surface of a concrete specimen with a coating thickness of 0.6 mm. Then, it was carbonized for 1 day under the conditions of CO2 concentration of 20%, RH of 100%, temperature of 10℃ and pressure of 0.2 bar to obtain an inorganic anti-carbonation coating on the surface of the concrete specimen.

[0049] Example 2

[0050] Weigh 100g of steel slag, 30g of water and 6g of polycarboxylate superplasticizer, and stir for 5 minutes at room temperature to obtain an inorganic anti-carbonation coating.

[0051] The above-mentioned inorganic anti-carbonation coating was applied to the surface of a concrete specimen with a coating thickness of 0.6 mm. Then, it was carbonized for 1 day under the conditions of CO2 concentration of 20%, RH of 100%, temperature of 10℃ and pressure of 0.2 bar to obtain an inorganic anti-carbonation coating on the surface of the concrete specimen.

[0052] Example 3

[0053] Weigh 100g of steel slag, 50g of water and 2g of polycarboxylate superplasticizer, and stir for 5 minutes at room temperature to obtain an inorganic anti-carbonation coating.

[0054] The above-mentioned inorganic anti-carbonation coating was applied to the surface of a concrete specimen with a coating thickness of 0.6 mm. Then, it was carbonized for 1 day under the conditions of CO2 concentration of 20%, RH of 100%, temperature of 10℃ and pressure of 0.2 bar to obtain an inorganic anti-carbonation coating on the surface of the concrete specimen.

[0055] Example 4

[0056] Weigh 100g of steel slag, 40g of water and 4g of polycarboxylate superplasticizer, and stir for 5 minutes at room temperature to obtain an inorganic anti-carbonation coating.

[0057] The above-mentioned inorganic anti-carbonation coating was applied to the surface of a concrete specimen with a coating thickness of 0.6 mm. Then, it was carbonized for 1 day under the conditions of CO2 concentration of 20%, RH of 100%, temperature of 10℃ and pressure of 0.2 bar to obtain an inorganic anti-carbonation coating on the surface of the concrete specimen.

[0058] Comparative Example 1

[0059] A comparative experiment was conducted based on the mixing ratios described in the literature *Potential application of geopolymers as protection coatings for caustic concrete: I*.

[0060] Weigh 100g of metakaolin and 10g of blast furnace slag and mix them to obtain a mixed dry material; mix water and the mixed dry material at a liquid-solid ratio of 0.60mL / g to obtain a composite geopolymer coating;

[0061] The above-mentioned composite geopolymer coating was applied to the surface of a concrete test block with a coating thickness of 0.5 mm. The block was then cured for 1 day at RH of 90±5% and 20±2℃. The composite geopolymer coating was obtained on the surface of the concrete test block. The average bond strength after 1 day of air curing was approximately 0.7 MPa.

[0062] Test case

[0063] According to the conventional tensile test, the adhesive strength of the inorganic anti-carbonization coating described in Examples 1-4 and Comparative Example 1 is determined by the strength of the coating being pulled out from the substrate surface.

[0064] The carbonation resistance of the inorganic anti-carbonation coatings described in Examples 1-4 and Comparative Example 1 was tested. The test method for carbonation resistance was as follows: Concrete specimens coated with the inorganic anti-carbonation coatings in Examples 1-4 and concrete specimens without any coating (referred to as the blank group) were placed in a carbonation chamber and cured for 1 day under the conditions of CO2 concentration of 20%, RH of 100%, temperature of 10℃ and pressure of 0.2 bar. The specimens were broken in the middle, and the fracture surface was sprayed with phenolphthalein. The uncolored area was the carbonized part. The depth of the uncolored area on each side of the concrete specimen was measured. Measurements were taken at 5 locations, and the average value of the measurements was taken as the carbonation depth value of the concrete specimen. The results are shown in Table 1.

[0065] Table 1. Performance test results of the inorganic anti-carbonization coatings described in Examples 1-4 and Comparative Example 1

[0066] source Bond strength (MPa) Carbonization depth (mm) Example 1 1.361 1.063 Example 2 1.321 0.850 Example 3 1.304 1.075 Example 4 1.005 1.163 Comparative Example 1 0.700 / Blank group / 2.521

[0067] Figure 3 This is a photograph of the inorganic anti-carbonization coating before carbonization as described in Example 2. Figure 4 This is a photograph of the inorganic anti-carbonization coating described in Example 2 after carbonization. Figure 5 A carbonation depth test image of a concrete specimen coated with the inorganic anti-carbonation coating described in Example 2; Figure 6 A graph showing the carbonation depth of a concrete specimen without any coating.

[0068] From Table 1 and Figures 3-4 It is known that the inorganic anti-carbonation coating of the present invention has a good transition layer due to the calcium carbonate generated after the steel slag carbonation is tightly bonded to the concrete, and has high bonding strength. Furthermore, the addition of SiC can further improve the bonding strength between the inorganic anti-carbonation coating and the concrete.

[0069] From Table 1 and Figures 5-6It is known that the inorganic anti-carbonization coating of the present invention has excellent anti-carbonization performance.

[0070] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. An inorganic carbonation-preventing coating, characterized by, An inorganic carbonation-preventing coating is coated on the surface of a concrete base to obtain a carbonated product; The specific steps are as follows: 2 g of SiC, 100 g of steel slag, 40 g of water and 4 g of polycarboxylate superplasticizer are weighed, and stirred at room temperature for 5 min to obtain an inorganic carbonation-preventing coating; The inorganic carbonation-preventing coating is coated on the surface of a concrete test block with a coating thickness of 0.6 mm, and then carbonated under the conditions of a CO2 concentration of 20%, RH of 100%, temperature of 10 ℃ and pressure of 0.2 bar for 1 d to obtain an inorganic carbonation-preventing coating on the surface of the concrete test block; The components of the steel slag are 34.25% CaO, 22.27% SiO2, 12.33% Al2O3, 15.09% Fe2O3, 9.11% MgO, 2.05% MnO, 0.38% Na2O and 1.01% SO3, and the particle size of the steel slag is 10 μm; The particle size of the SiC is 0.8 μm; The water-reducing rate of the polycarboxylate superplasticizer is 50%.

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