A multifunctional coating for aesthetically pleasing concrete surfaces and its preparation method

Abstract

This invention belongs to the field of concrete engineering decoration technology, specifically relating to a multifunctional coating for aesthetically pleasing concrete surfaces and its preparation method. The multifunctional coating comprises a base layer, a middle layer, and a top layer sequentially applied to the concrete surface. The base layer is made from a water-repellent agent. The middle layer, by weight percentage, comprises: 65-80% cement-based penetrating crystalline waterproofing material and 20-35% sheet-like graphene oxide-modified pure acrylic emulsion. The top layer, by weight percentage, comprises: 25-50% water-repellent agent, 50-70% acrylic emulsion, and 0.2-0.5% nanomaterials. This multifunctional coating exhibits high bonding strength, low shrinkage, high flexibility, UV resistance, and integrated performance with the protected structure. Furthermore, its coefficient of thermal expansion is similar to that of cement, preventing detachment and voids in the later stages, resulting in better durability.

Description

Technical Field

[0001] This invention belongs to the field of concrete engineering decoration technology, specifically relating to a multifunctional coating for aesthetically pleasing concrete surfaces and its preparation method. Background Technology

[0002] Concrete, as a primary structural material, is widely used in industrial and civil buildings, roads and bridges, and municipal engineering. The requirements for concrete quality are increasingly stringent, but surface defects caused by various reasons are difficult to completely eliminate, especially problems such as color differences and grout leakage, resulting in unsightly appearances over large areas. With the development of building technology, modern architects emphasize the inherent texture of concrete, but achieving this effect in actual construction is challenging. Therefore, surface finishing is needed to beautify the concrete surface and express the building's simple, natural, and stable character. In light of this, a material that can both beautify the concrete surface and possess high durability and crack resistance has a broad market demand.

[0003] Chinese patent CN108165167A discloses a color-correcting coating material for concrete surfaces, comprising a primer of silicone emulsion, other additives, and water; a mid-coat of polymer emulsion, fillers, pigments, other additives, and water; and a topcoat of fluorinated resin polymer, other additives, and water. While this type of coating has a corrective function, it is only suitable for "restoring the old to its original state," not for restoring the old to its new state. Chinese patent CN113149710A discloses a concrete surface modifier and its preparation method, comprising: 55-85 parts deionized water, 15-30 parts organic-inorganic hybrid sol, 0-1 part colorant, 0.5-2 parts γ-aminopropyltriethoxysilane, 1-3 parts AMP95, and 1-5 parts Acronal S695P acrylic powder. While this type of coating has a corrective function, it lacks aging resistance. Furthermore, current decorative materials on the market primarily focus on decorative effects, neglecting the role of decorative materials in improving the properties of the concrete itself. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a multifunctional coating for aesthetically pleasing concrete surfaces and its preparation method. This multifunctional coating exhibits high bonding strength, low shrinkage, high flexibility, UV resistance, and seamless integration with the protected structure. Furthermore, its coefficient of thermal expansion is similar to that of cement, preventing detachment and voids in the later stages, resulting in better durability.

[0005] Specifically, the present invention provides the following technical solutions:

[0006] A multifunctional coating for aesthetically pleasing concrete surfaces, comprising a base layer, an intermediate layer, and a top layer sequentially applied to the concrete surface.

[0007] The raw material of the bottom layer is a water-repellent agent;

[0008] The raw materials of the middle layer, by mass percentage, include: 65-80% cement-based penetrating crystalline waterproofing material and 20-35% sheet-structured graphene oxide-modified pure acrylic emulsion; the cement-based penetrating crystalline waterproofing material is a mixture of modified lithium slag, calcium ion compensator, complexing agent, precipitant, and zirconium silicone in a mass ratio of 40-55:18-30:9-19:10-23:0-5.

[0009] The raw materials for the surface layer, by weight percentage, include: 25-50% water-repellent agent, 50-70% acrylic emulsion, and 0.2-0.5% nanomaterials.

[0010] The multifunctional coating provided by this invention comprises three layers: a base layer, a middle layer, and a top layer. The base layer is a water-repellent agent, which improves the waterproof performance of the coating while reducing the water absorption effect of old concrete on the middle layer material. The middle layer is a coating made by mixing cement-based penetrating crystalline waterproof material and modified pure acrylic emulsion in a certain proportion. This coating has high bonding strength, can beautify the appearance of concrete, and the penetrating crystalline component can improve the durability of the old concrete itself, extend the service life of the structure, and also play a self-repairing role when the coating cracks. The top layer is composed of a water-repellent agent, pure acrylic emulsion, and nanomaterials. The water-repellent agent can form an organic water-repellent layer on the concrete surface to prevent water intrusion, the pure acrylic emulsion has a matte effect, making the concrete simple, natural, and stable, and the nanomaterials can improve the aging resistance, adhesion, and wear resistance of the top layer material. Applying the multifunctional coating of this invention to the concrete surface ensures aesthetics while also providing anti-corrosion, waterproofing, and anti-detachment functions, thus it can be widely used in large-area exposed concrete projects such as highways, bridges, water conservancy, and ports.

[0011] Preferably, any of the hydrophobic agents is n-octyltriethoxysilane.

[0012] Preferably, the sheet-structured graphene oxide-modified pure acrylic emulsion is prepared by using pure acrylic emulsion and sheet-structured graphene in a mass ratio of 1:0.002 to 0.006.

[0013] The pure acrylic emulsion comprises, by mass percentage: 5-10% hydroxyl-terminated polydimethylsiloxane (PDMS) and 90-95% polyacrylate emulsion; the solid content of the polyacrylate emulsion is 45-55%.

[0014] Preferably, the calcium ion compensator comprises calcium formate and calcium hydroxide in a mass ratio of 1:5 to 15.

[0015] Preferably, the complexing agent comprises ethylenediaminetetraacetic acid (EDTA) and sodium citrate in a mass ratio of 0.1–0.9:0.1–0.9.

[0016] Preferably, the precipitant is sodium carbonate with a fineness of ≥200 mesh.

[0017] Preferably, the method for preparing the modified lithium slag includes: spraying 0.8-1.2% (by mass of lithium slag) of a hydrophobic agent onto the surface of the lithium slag, mixing thoroughly, allowing it to stand for 24-36 hours, drying at 100-105°C, and then ball milling to obtain a specific surface area of ​​300-450 m². 2 / kg of modified lithium slag.

[0018] Preferably, the nanomaterial is a mixture of nano-TiO2 and nano-SiC in a mass ratio of 1:1 to 2.

[0019] Preferably, the thickness of the bottom layer is 5–50 μm;

[0020] The thickness of the middle layer is 0.4–0.6 mm;

[0021] The thickness of the surface layer is 0.05 to 0.1 mm.

[0022] The present invention also provides a method for preparing the above-mentioned multifunctional coating, comprising the following steps:

[0023] (1) Perform base treatment on the concrete surface;

[0024] (2) Spray the base layer material onto the treated concrete surface, then roll the middle layer material after drying, and finally spray the top layer material after drying.

[0025] The beneficial effects of this invention are at least as follows:

[0026] 1) The present invention provides a multifunctional coating for aesthetically pleasing concrete surfaces, comprising three layers: a base layer, a middle layer, and a top layer. The base layer is a water-repellent agent, which improves waterproof performance while reducing the water absorption of the middle layer material by the old concrete, thereby reducing the risk of drying shrinkage and cracking of the middle layer material.

[0027] 2) The present invention provides a multifunctional coating for aesthetically pleasing concrete surfaces, wherein the intermediate layer is a modified pure acrylic emulsion with hydroxyl-terminated PDMS (chemical formula (C2H6OSi)). nThis material is made from polyacrylate emulsion and layered graphene oxide, with each component exhibiting a complementary effect. Hydroxyl-terminated PDMS provides grafting sites with cement hydration products, forming a low surface energy latex film structure on the surface of these products. This imparts hydrophobic characteristics to cement-based materials, improving coating density, durability, tensile strength, and adhesion strength. Layered graphene oxide extends the penetration path of corrosive ions, further enhancing durability. Simultaneously, hydroxyl-terminated PDMS improves the dispersion stability of layered graphene oxide, exerting its micro-regulation effect to reduce agglomeration. The copolymerization of hydroxyl-terminated PDMS and polyacrylate improves the weather resistance, water resistance, and thermal stability of polyacrylate. The layered graphene oxide enhances the mechanical properties of polyacrylate.

[0028] 3) This invention provides a multifunctional coating for aesthetically pleasing concrete surfaces. The middle layer, a cement-based penetrating crystalline waterproofing material, is composed of modified lithium slag, calcium ion compensator, complexing agent, precipitant, and zirconium silicate. The components complement each other. The complexing agent can complex free calcium ions in concrete to form water-soluble but unstable calcium complexes, which then react with anionic groups within the concrete to form insoluble precipitates. The micro-expansion and porous water-retaining effect of lithium slag reduces cracking of the coating. The hydrophobic effect of the modified lithium slag reduces water evaporation during the plastic stage of the coating. Zirconium silicate promotes secondary hydration of unhydrated cement particles in old concrete. Therefore, the multifunctional coating of this invention improves concrete durability and has a certain crack repair effect. Simultaneously, the complexing agent increases the solubility of the calcium ion compensator in water and reacts with the precipitant to form insoluble precipitates. The combined use of modified lithium slag and zirconium silicate further enhances its waterproofing and durability.

[0029] 4) The present invention provides a multifunctional coating for aesthetic concrete surfaces. The surface layer is composed of a water-repellent agent, acrylic emulsion, and nanomaterials. The water-repellent agent can form an organic water-repellent layer with the surface of the intermediate material to prevent water intrusion. The acrylic emulsion has a matte effect, making the concrete simple, natural, and stable. Nano-TiO2 can improve the self-cleaning effect of the surface layer, and nano-SiC can improve the wear resistance of the surface layer.

[0030] 5) The present invention provides a multifunctional coating for aesthetically pleasing concrete surfaces. When applied to concrete surfaces, it ensures aesthetics while exhibiting high interfacial bonding strength, low shrinkage, high flexibility, resistance to ultraviolet radiation, and excellent aging resistance. It also enhances the durability of concrete to a certain extent. It is easy to produce on a large scale in industrial applications, is simple to construct, and can be widely used in large-area exposed concrete projects such as highways, bridges, water conservancy projects, and ports. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the art, or in accordance with the product manual.

[0032] In the following embodiments, the cement-based penetrating crystalline waterproofing material is a mixture of modified lithium slag, calcium ion compensator, complexing agent, precipitant, and zirconium silicate in a mass ratio of 50:18:10:20:2; the modified lithium slag is prepared by spraying 0.9% water-repellent agent onto the surface of the lithium slag, mixing it evenly, letting it stand for 1 day, drying it at 100°C, and then ball milling it to obtain a specific surface area of ​​420 m². 2 / kg of modified lithium slag; the calcium ion compensator is a mixture of calcium formate and calcium hydroxide in a mass ratio of 1:5; the complexing agent is a mixture of ethylenediaminetetraacetic acid (EDTA) and sodium citrate in a mass ratio of 0.3:0.7; the precipitant is sodium carbonate with a fineness ≥200 mesh;

[0033] The specific preparation method of the layered graphene oxide-modified pure acrylic emulsion is as follows:

[0034] Step 1: Take 100 parts by weight of hydroxyl-terminated polydimethylsiloxane (Wuhan Rongcan Biotechnology Co., Ltd.) and place it in a container. Add 4 parts by weight of sheet-structured graphene oxide, ultrasonically disperse for 1 hour, and heat in a 60°C water bath for 30 minutes.

[0035] Step 2: Take 1800 parts by weight of 50% polyacrylate emulsion and place it in a container. Heat it in a 60°C water bath for 30 minutes. Add the solution obtained in Step 1 dropwise over 10 minutes. Heat the solution to 80°C and react for 1.5 hours. Then cool it to room temperature to obtain graphene oxide modified pure acrylic emulsion.

[0036] The acrylic emulsion mentioned is derived from JK-NBS cement modifier acrylic emulsion from Nanjing Ruide High-Tech Co., Ltd.

[0037] Example 1

[0038] A multifunctional coating for aesthetically pleasing concrete surfaces consists of three layers: a 10μm base coat, a 0.5mm intermediate coat, and a 0.08mm top coat.

[0039] The bottom layer is made of n-octyltriethoxysilane;

[0040] The middle layer consists of cement-based penetrating crystalline waterproofing material with a mass ratio of 7:3 and sheet-like graphene oxide-modified pure acrylic emulsion.

[0041] The surface layer is made of n-octyltriethoxysilane, acrylic emulsion, and nanomaterials in a mass ratio of 3:6.7:0.3, wherein the nanomaterials are TiO2 and SiC in a mass ratio of 1:1.

[0042] Comparative Example 1

[0043] A multifunctional coating for aesthetically pleasing concrete surfaces, differing from Example 1 only in that it does not contain a base layer.

[0044] Specifically, it consists of two layers: a middle layer and a top layer.

[0045] The middle layer consists of cement-based penetrating crystalline waterproofing material with a mass ratio of 7:3 and sheet-like graphene oxide-modified pure acrylic emulsion.

[0046] The surface layer is made of n-octyltriethoxysilane, acrylic emulsion, and nanomaterials in a mass ratio of 3:6.7:0.3, wherein the nanomaterials are TiO2 and SiC in a mass ratio of 1:1.

[0047] Comparative Example 2

[0048] A multifunctional coating for aesthetically pleasing concrete surfaces, differing from Example 1 only in that the pure acrylic emulsion is not modified with graphene to form a sheet structure.

[0049] Specifically, it consists of three layers: a bottom layer, a middle layer, and a top layer.

[0050] The bottom layer is made of n-octyltriethoxysilane;

[0051] The middle layer material consists of a cement-based penetrating crystalline waterproofing material and pure acrylic emulsion in a mass ratio of 7:3.

[0052] The surface layer is made of n-octyltriethoxysilane, acrylic emulsion, and nanomaterials in a mass ratio of 3:6.7:0.3, wherein the nanomaterials are TiO2 and SiC in a mass ratio of 1:1.

[0053] Comparative Example 3

[0054] A multifunctional coating for aesthetically pleasing concrete surfaces, differing from Example 1 only in that the raw material of the intermediate layer does not contain cement-based penetrating crystalline waterproofing material.

[0055] Specifically, it consists of three layers: a bottom layer, a middle layer, and a top layer.

[0056] The bottom layer is made of n-octyltriethoxysilane;

[0057] The middle layer is made from modified pure acrylic emulsion;

[0058] The surface layer is made of n-octyltriethoxysilane, acrylic emulsion, and nanomaterials in a mass ratio of 3:6.7:0.3, wherein the nanomaterials are TiO2 and SiC in a mass ratio of 1:1.

[0059] Comparative Example 4

[0060] A multifunctional coating for aesthetically pleasing concrete surfaces, differing from Example 1 only in that the surface layer does not contain nanomaterials.

[0061] Specifically, it consists of three layers: a bottom layer, a middle layer, and a top layer.

[0062] The bottom layer is made of n-octyltriethoxysilane;

[0063] The middle layer consists of cement-based penetrating crystalline waterproofing material with a mass ratio of 7:3 and sheet-like graphene oxide-modified pure acrylic emulsion.

[0064] The surface layer is made of n-octyltriethoxysilane and acrylic emulsion in a mass ratio of 3:7.

[0065] Test case

[0066] According to the proportions in Table 1, a multifunctional coating is prepared on the surface of the molded base concrete. The specific steps are as follows:

[0067] (1) Base treatment of concrete surface: Grind the concrete surface to ensure that the concrete surface is flat, dense and firm, and remove surface laitance, dust, oil stains, mold, etc. At the same time, for larger defective areas, use cement-based penetrating crystalline waterproof material to repair and level.

[0068] (2) Spray the base coat material onto the treated concrete surface, then roll the intermediate coat material after drying, and finally spray the top coat material after drying. Specifically: First, apply the base coat by spraying two coats of water-repellent agent with a 3-hour interval between coats; after the base coat is completely dry, apply the intermediate coat material. The first coat of the intermediate coat should be about 0.3mm thick to facilitate leveling the base surface. Note that the troweling direction should be the same and should not be repeated back and forth; after the first coat is surface dry, use fine sandpaper to sand away scratches, and then apply the second coat material. The thickness of the second coat should be about 0.2mm; the top coat should be sprayed after the intermediate coat is surface dry.

[0069] Meanwhile, it should be noted that when preparing the raw materials for the middle layer, the cement-based penetrating crystalline waterproofing material and the modified pure acrylic emulsion should be mixed evenly. High-speed mixing equipment should be used during mixing, and the mixing time should be no less than 3 minutes. The mixture should be used immediately after mixing and should not be mixed in large quantities at one time. Each batch of material should be used up within 60 minutes.

[0070] Table 1. Mix Proportions for Foundation Concrete

[0071]

[0072] The concrete water absorption ratio was tested according to JC474-2008 "Waterproofing Agent for Mortar and Concrete". The early crack resistance, electrical flux, and seepage pressure were tested according to GBT 50082-2009 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete". The bonding strength was tested according to JCT 864-2008 "Polymer Emulsion Waterproofing Coating for Buildings". The weather resistance was tested according to JGT 335-2011 "Film-Forming Coatings for Concrete Structure Protection". The UV resistance was tested according to JGT 337-2011 "Penetrating Coatings for Concrete Structure Protection". The results are shown in Table 2.

[0073] Table 2 Performance Indicators of Examples and Comparative Examples

[0074]

[0075]

[0076] As can be clearly seen from Table 2, Comparative Example 1, due to the lack of a hydrophobic base treatment, exhibited coating cracking and reduced waterproofing performance; Comparative Example 2, lacking the layered graphene modification of the pure acrylic emulsion, showed reduced waterproofing performance compared to the example; Comparative Example 3, with its mid-layer material not containing cement-based penetrating crystalline waterproofing material, showed reduced adhesion and waterproofing performance compared to the example; and Comparative Example 4, lacking nano-TiO2 and SiC modification of the surface layer material, showed reduced contact angle and waterproofing performance compared to the example, and failed to meet the requirements for weather resistance and UV resistance.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multifunctional coating for aesthetically pleasing concrete surfaces, characterized in that, This includes the base layer, intermediate layer, and top layer that are sequentially applied to the concrete surface; The raw material of the bottom layer is a water-repellent agent; The raw materials of the middle layer, by mass percentage, include: 65-80% cement-based penetrating crystalline waterproofing material and 20-35% sheet-structured graphene oxide-modified pure acrylic emulsion; the cement-based penetrating crystalline waterproofing material is a mixture of modified lithium slag, calcium ion compensator, complexing agent, precipitant, and zirconium silicone in a mass ratio of 40-55:18-30:9-19:10-23:0-5. The raw materials of the surface layer include, by mass percentage: 25-50% water-repellent agent, 50-70% acrylic emulsion, and 0.2-0.5% nanomaterials, and the sum of the mass percentages of all raw materials is 100%.

2. The multifunctional coating for aesthetically pleasing concrete surfaces according to claim 1, characterized in that, Any of the hydrophobic agents mentioned is n-octyltriethoxysilane.

3. The multifunctional coating for aesthetically pleasing concrete surfaces according to claim 1 or 2, characterized in that, The sheet-structured graphene oxide-modified pure acrylic emulsion is prepared by mixing pure acrylic emulsion and sheet-structured graphene in a mass ratio of 1:0.002~0.

006. The pure acrylic emulsion comprises, by mass percentage: 5-10% hydroxyl-terminated polydimethylsiloxane and 90-95% polyacrylate emulsion; the solid content of the polyacrylate emulsion is 45-55%.

4. The multifunctional coating for aesthetically pleasing concrete surfaces according to claim 1 or 2, characterized in that, The calcium ion compensator comprises calcium formate and calcium hydroxide in a mass ratio of 1:5 to 15.

5. The multifunctional coating for aesthetically pleasing concrete surfaces according to claim 1 or 2, characterized in that, The complexing agent comprises ethylenediaminetetraacetic acid and sodium citrate in a mass ratio of 0.1~0.9:0.1~0.

9.

6. The multifunctional coating for aesthetically pleasing concrete surfaces according to claim 1 or 2, characterized in that, The precipitant is sodium carbonate with a fineness of ≥200 mesh.

7. The multifunctional coating for aesthetically pleasing concrete surfaces according to claim 1 or 2, characterized in that, The method for preparing the modified lithium slag includes: spraying 0.8-1.2% of a water-repellent agent onto the surface of the lithium slag, mixing it evenly, letting it stand for 24-36 hours, drying it at 100-105℃, and then ball milling it to obtain a specific surface area of ​​300-450 m². 2 / kg of modified lithium slag.

8. The multifunctional coating for aesthetically pleasing concrete surfaces according to claim 1 or 2, characterized in that, The nanomaterial is a mixture of nano-TiO2 and nano-SiC in a mass ratio of 1:1~2.

9. The multifunctional coating for aesthetically pleasing concrete surfaces according to claim 1 or 2, characterized in that, The thickness of the bottom layer is 5~50μm; The thickness of the middle layer is 0.4~0.6mm; The thickness of the surface layer is 0.05~0.1mm.

10. A method for preparing a multifunctional coating for an aesthetically pleasing concrete surface as described in any one of claims 1-9, characterized in that, Includes the following steps: (1) Perform base treatment on the concrete surface; (2) Spray the base layer material onto the treated concrete surface, roll the middle layer material after drying, and spray the top layer material after drying.

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