Multifunctional coating for beautiful concrete surface and preparation method thereof

Abstract

The invention belongs to the technical field of concrete engineering decoration, and particularly relates to a multifunctional coating for a beautiful concrete surface and a preparation method thereof. The multifunctional coating comprises a bottom layer, a middle layer and a surface layer which are sequentially arranged on the surface of concrete in a covering mode. The raw material of the bottom layer is a water repellent; the middle layer is prepared from the following raw materials in percentage by mass: 65 to 80 percent of cement-based capillary crystalline waterproof material and 20 to 35 percent of graphene oxide modified pure acrylic emulsion with a lamellar structure; the surface layer is prepared from the following raw materials in percentage by mass: 25 to 50 percent of water repellent, 50 to 70 percent of acrylic emulsion and 0.2 to 0.5 percent of nano material. The multifunctional coating is high in bonding strength, low in shrinkage rate, high in flexibility and resistant to ultraviolet irradiation, achieves an integrated effect with a protected structure, has the thermal expansion coefficient similar to that of a cement material, does not fall off or void in the later period, and is better in durability.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete engineering decoration, and particularly relates to a multifunctional coating for an aesthetically pleasing concrete surface and a preparation method thereof. Background Art

[0002] As a major structural material, concrete is widely used in industry, civil construction, roads and bridges, and municipal engineering. The requirements for concrete quality are getting higher and higher, but surface defects caused by various reasons are difficult to cure, especially the problems of surface color difference and leakage, which are prominent and have poor appearance over a large area. With the development of construction technology, modern architects focus on applying the texture of concrete materials themselves, but it is difficult to achieve this effect in actual construction. Appearance treatment is needed to beautify the concrete surface and express the simple, natural and calm emotions of the building. In view of this, a material that can beautify the concrete surface and has high durability and crack resistance has a broad market demand.

[0003] Chinese patent CN108165167A discloses a concrete surface color difference modifying coating material, which uses silicone emulsion, other additives, and water to form a primer, polymer emulsion, filler, pigment, other additives, and water to form a middle coat, and fluorine-modified resin polymer, other additives, and water to form a top coat. Although this type of coating has a modifying function, it is only suitable for the scene of "repairing the old as it is old" and is not suitable for the scene of repairing the old as it is new. Chinese patent CN113149710A discloses a concrete surface modifier and its preparation method, including: 55-85 parts of deionized water, 15-30 parts of organic-inorganic hybrid material sol, 0-1 part of colorant, 0.5-2 parts of γ-aminopropyl triethoxysilane, 1-3 parts of AMP95, and 1-5 parts of Acronal S695P acrylic powder. Although this type of coating has a modifying function, it does not have aging resistance. In addition, the finishing materials on the market currently focus on decorative effects, and fail to pay attention to the role of finishing materials in improving the performance of concrete itself. Summary of the invention

[0004] In view of the defects existing in the prior art, the present invention provides a multifunctional coating for an aesthetically pleasing concrete surface and a preparation method thereof. The multifunctional coating has high bonding strength, low shrinkage, high flexibility, resistance to ultraviolet radiation, and can be integrated with the protected structure. The thermal expansion coefficient is similar to that of cement materials, and it will not fall off or become hollow in the later stage, and has better durability.

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

[0006] A multifunctional coating for a beautiful concrete surface, comprising a bottom layer, a middle layer and a surface layer sequentially covered on the concrete surface;

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

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

[0009] The raw materials of the surface layer include, by mass percentage, 25-50% of water repellent, 50-70% of propylene latex, and 0.2-0.5% of nanometer material.

[0010] The multifunctional coating provided by the present invention comprises three layers: bottom, middle and surface. The bottom layer is a water repellent, which can reduce the water absorption effect of old concrete on the middle layer material while improving the waterproof performance of the coating; the middle layer is a coating made by mixing cement-based permeable crystallization waterproof material and modified pure acrylic emulsion in a certain proportion. The coating has high bonding strength and can beautify the appearance of concrete. The permeable crystallization component can improve the durability of the old concrete body and extend the service life of the structure. At the same time, it can play a self-repairing role when cracks appear in the coating; the surface layer is composed of a water repellent, pure acrylic emulsion and nanomaterials. The water repellent can form an organic water repellent layer on the surface of the concrete to prevent water from invading. The pure acrylic emulsion has a matte effect, making the concrete plain and natural. The nanomaterial can improve the aging resistance, bonding and wear resistance of the surface material. The multifunctional coating of the present invention is applied to the surface of concrete, which has the functions of anti-corrosion, waterproofing and anti-falling while ensuring beauty, so that it can be widely used in large-area exposed concrete projects such as roads, bridges, water conservancy projects and ports.

[0011] Preferably, any of the water repellents is n-octyltriethoxysilane.

[0012] Preferably, the lamellar graphene oxide modified pure acrylic emulsion is prepared from pure acrylic emulsion and lamellar graphene oxide in a mass ratio of 1:0.002-0.006;

[0013] The pure acrylic emulsion comprises, by mass percentage, 5-10% of hydroxyl-terminated polydimethylsiloxane (PDMS) and 90-95% of 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 ≥ 200 mesh.

[0017] Preferably, the preparation method of the modified lithium slag comprises: spraying 0.8-1.2% of a water repellent (based on the mass of the lithium slag) on ​​the surface of the lithium slag, mixing evenly and placing for 24-36 hours, drying at 100-105°C, and ball milling to obtain a specific surface area of ​​300-450m 2 / kg of modified lithium slag.

[0018] Preferably, the nano material 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 to 50 μm;

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

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

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

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

[0024] (2) Spray the raw materials of the bottom layer on the treated concrete surface, roll on the raw materials of the middle layer after drying, and spray the raw materials of the surface layer after drying.

[0025] The beneficial effects of the present invention are at least:

[0026] 1) The present invention provides a multifunctional coating for a beautiful concrete surface, comprising three layers: a bottom layer, a middle layer and a surface layer. The bottom layer is a water repellent, which can improve the waterproof performance while reducing the water absorption of the old concrete to the middle layer material, thereby reducing the risk of shrinkage and cracking of the middle layer material;

[0027] 2) The present invention provides a multifunctional coating for a beautiful concrete surface, wherein the modified pure acrylic emulsion in the middle layer is composed of hydroxyl-terminated PDMS (chemical formula: (C2H6OSi) n) and polyacrylate emulsion and lamellar graphene oxide, and the raw material components complement each other. Among them, hydroxyl-terminated PDMS can provide grafting sites with cement hydration products, form a latex film structure with low surface energy on the surface of cement hydration products, give cement-based materials hydrophobic characteristics, improve coating density, durability, tensile strength, and bonding strength, and lamellar graphene oxide can extend the penetration path of corrosive ions and further improve durability. At the same time, hydroxyl-terminated PDMS can improve the dispersion stability of lamellar graphene oxide, exert its micro-regulatory effect to reduce agglomeration; hydroxyl-terminated PDMS and polyacrylate undergo copolymerization to improve the weather resistance, water resistance and thermal stability of polyacrylate; lamellar graphene oxide can improve the mechanical properties of polyacrylate;

[0028] 3) The present invention provides a multifunctional coating for a beautiful concrete surface, wherein the cement-based penetrating crystallization waterproof material in the middle layer is composed of modified lithium slag, calcium ion compensator, chelating agent, precipitant, and zirconium silicone, and each raw material component has a complementary advantage effect. Among them, the chelating agent can chelate the free calcium ions in the concrete to form a water-soluble but unstable calcium complex, which then meets the anion groups inside the concrete to generate an insoluble precipitate. The micro-expansion and porous water storage effect of the lithium slag can reduce the cracking of the coating. The hydrophobic effect of the modified lithium slag can reduce water evaporation in the plastic stage of the coating. Zirconium silicone can promote the secondary hydration of unhydrated cement particles in the old concrete. Therefore, the multifunctional coating of the present invention has the effect of improving the durability of concrete and has a certain crack repair effect. At the same time, the chelating agent can increase the solubility of the calcium ion compensator in water, react with the precipitant, and generate an insoluble precipitate; the modified lithium slag and zirconium silicone are mixed to further improve its waterproof and durable properties;

[0029] 4) The present invention provides a multifunctional coating for a beautiful concrete surface, wherein the surface layer is composed of a water repellent, acrylic emulsion, and nanomaterials. The water repellent can form an organic water repellent layer with the surface of the middle layer material to prevent water intrusion. The acrylic emulsion has a matte effect, making the concrete plain and natural. 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 an aesthetically pleasing concrete surface, which is applied on the concrete surface. While ensuring the aesthetics, it has high interface bonding strength, low shrinkage, high flexibility, resistance to ultraviolet radiation, and excellent aging resistance. It also has a certain effect of improving the durability of concrete, is easy to produce on a large scale, is simple to construct, and can be widely used in large-area exposed concrete projects such as roads, bridges, water conservancy projects, and ports. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention is described clearly and completely below. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention. If no specific technology or conditions are specified in the embodiments, the technology or conditions described in the literature in the field or the product instructions are used.

[0032] In the following embodiment, the cement-based permeable crystallization waterproof material is a mixture of modified lithium slag, calcium ion compensator, complexing agent, precipitant, and silicone zirconium in a mass ratio of 50:18:10:20:2; the preparation method of the modified lithium slag is as follows: spray 0.9% of a water repellent on the surface of the lithium slag, mix well, place for 1 day, dry at 100°C, and perform ball milling to obtain a specific surface area of ​​420m 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 of ≥200 mesh;

[0033] The preparation method of the graphene oxide modified pure acrylic emulsion with a lamellar structure is specifically as follows:

[0034] Step 1, 100 parts by weight of hydroxyl-terminated polydimethylsiloxane (Wuhan Rongcan Biotechnology Co., Ltd.) was placed in a container, 4 parts by weight of graphene oxide with a lamellar structure was added, ultrasonically dispersed for 1 hour, and heated in a 60° C. water bath for 30 minutes;

[0035] Step 2: Take 1800 parts by weight of a polyacrylate emulsion with a solid content of 50% and place it in a container, heat it in a 60°C water bath for 30 minutes, add the solution prepared in step 1 dropwise within 10 minutes, heat to 80°C and react for 1.5 hours, then cool to room temperature to obtain a graphene oxide modified pure acrylic emulsion.

[0036] The propylene emulsion is derived from JK-NBS cement modifier propylene emulsion produced by Nanjing Ruidi High-tech Co., Ltd.

[0037] Example 1

[0038] A multifunctional coating for beautiful concrete surface, consisting of 10μm bottom layer, 0.5mm middle layer and 0.08mm surface layer, including:

[0039] The raw material for the bottom layer is n-octyltriethoxysilane;

[0040] The raw materials of the middle layer are cement-based permeable crystalline waterproof material and graphene oxide-modified pure acrylic emulsion with a lamellar structure in a mass ratio of 7:3;

[0041] The raw materials of the surface layer are n-octyltriethoxysilane, propylene 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 an aesthetically pleasing concrete surface, which is different from Example 1 in that it does not include a base layer.

[0044] Specifically, it consists of two layers: the middle layer and the surface layer, among which:

[0045] The raw materials of the middle layer are cement-based permeable crystalline waterproof material and graphene oxide-modified pure acrylic emulsion with a lamellar structure in a mass ratio of 7:3;

[0046] The raw materials of the surface layer are n-octyltriethoxysilane, propylene 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 an aesthetically pleasing concrete surface, which is different from Example 1 only in that the pure acrylic emulsion is not modified with graphene having a lamellar structure.

[0049] Specifically, it consists of three layers: bottom layer, middle layer and surface layer, among which:

[0050] The raw material for the bottom layer is n-octyltriethoxysilane;

[0051] The middle layer material is cement-based penetrating crystallization waterproof material and pure acrylic emulsion with a mass ratio of 7:3;

[0052] The raw materials of the surface layer are n-octyltriethoxysilane, propylene 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 an aesthetically pleasing concrete surface, which is different from Example 1 only in that the raw materials of the middle layer do not contain cement-based penetrating crystalline waterproof material.

[0055] Specifically, it consists of three layers: bottom layer, middle layer and surface layer, among which:

[0056] The raw material for the bottom layer is n-octyltriethoxysilane;

[0057] The raw material of the middle layer is modified pure acrylic emulsion;

[0058] The raw materials of the surface layer are n-octyltriethoxysilane, propylene 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 an aesthetically pleasing concrete surface, which is different from Example 1 only in that the raw material of the surface layer does not contain nanomaterials.

[0061] Specifically, it consists of three layers: bottom layer, middle layer and surface layer, among which:

[0062] The raw material for the bottom layer is n-octyltriethoxysilane;

[0063] The raw materials of the middle layer are cement-based permeable crystalline waterproof material and graphene oxide-modified pure acrylic emulsion with a lamellar structure in a mass ratio of 7:3;

[0064] The raw materials of the surface layer are n-octyltriethoxysilane and propylene emulsion in a mass ratio of 3:7.

[0065] Test example

[0066] The base concrete is formed according to the proportions in Table 1, and the multifunctional coating is prepared on the surface thereof. The specific steps are as follows:

[0067] (1) Carry out base treatment on the concrete surface: Grind the concrete surface to ensure that it is flat, dense and strong, and remove surface slurry, dust, oil stains, mold, etc. At the same time, use cement-based penetrating crystallization waterproof materials to repair and level the larger defective parts;

[0068] (2) Spray the raw materials of the bottom layer on the treated concrete surface, roll the raw materials of the middle layer after drying, and then spray the raw materials of the surface layer after drying. Specifically: First, carry out the bottom layer construction, spray the water repellent twice, and the spraying time interval is 3 hours; after the bottom layer is completely dry, carry out the middle layer construction, and the thickness of the first middle layer construction is controlled to be about 0.3mm, which is convenient for leveling the base surface. Note that the direction of spreading and pressing should be in the same direction, and the surface cannot be repeatedly closed back and forth; after the first layer is dry, use fine sandpaper to polish and remove scratches, and then carry out the second layer of construction. The thickness of the second layer is controlled to be about 0.2mm; spray the surface layer after the middle layer is dry.

[0069] At the same time, it should be noted that when configuring the raw materials for the middle layer, the cement-based penetrating crystalline waterproof material and the modified pure acrylic emulsion should be mixed evenly. High-speed mixing equipment should be used for mixing. The mixing time should be no less than 3 minutes. Use as soon as you mix. Do not mix too much at one time. Each mixing should be used up within 60 minutes.

[0070] Table 1 Base concrete mix ratio

[0071]

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

[0073] Table 2 Performance indexes of embodiments and comparative examples

[0074]

[0075]

[0076] It can be clearly seen from Table 2 that Comparative Example 1 has cracks in the coating and reduced waterproof performance due to the lack of bottom layer hydrophobic treatment; Comparative Example 2 has not modified the pure acrylic emulsion with graphene of a lamellar structure, which shows that the waterproof performance of Comparative Example 2 is lower than that of the embodiment; the middle layer material of Comparative Example 3 does not contain cement-based penetrating crystalline waterproof material, which shows that the bonding performance and waterproof performance of Comparative Example 3 are lower than those of the embodiment; Comparative Example 4 has not modified the surface layer material with nano-TiO2 and SiC, which shows that the contact angle and waterproof performance of Comparative Example 4 are lower than those of the embodiment, and cannot meet the weather resistance and UV resistance index requirements.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multifunctional coating for an aesthetically pleasing concrete surface, characterized in that: It includes a bottom layer, a middle layer and a surface layer which are sequentially covered on the concrete surface; The raw material of the bottom layer is a water repellent; The raw materials of the middle layer include, by mass percentage: 65-80% of cement-based permeable crystallization waterproof material and 20-35% of graphene oxide modified pure acrylic emulsion with a lamellar structure; the cement-based permeable crystallization waterproof material is a mixture of modified lithium slag, calcium ion compensator, complexing agent, precipitant and silicone zirconium 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% of water repellent, 50-70% of propylene latex, and 0.2-0.5% of nanometer material.

2. The multifunctional coating for an aesthetically pleasing concrete surface according to claim 1, characterized in that: Any of the water repellents is n-octyltriethoxysilane.

3. The multifunctional coating for an aesthetically pleasing concrete surface according to claim 1 or 2, characterized in that: The lamellar graphene oxide modified pure acrylic emulsion is prepared from pure acrylic emulsion and lamellar graphene oxide in a mass ratio of 1:0.002-0.006; The pure acrylic emulsion comprises, by mass percentage, 5-10% of hydroxyl-terminated polydimethylsiloxane and 90-95% of polyacrylate emulsion; the solid content of the polyacrylate emulsion is 45-55%.

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

5. The multifunctional coating for an aesthetically pleasing concrete surface 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 an aesthetically pleasing concrete surface 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 an aesthetically pleasing concrete surface according to claim 1 or 2, characterized in that: The preparation method of the modified lithium slag comprises: spraying 0.8-1.2% of a water-repellent agent on the surface of the lithium slag, mixing evenly and placing for 24-36 hours, drying at 100-105° C., and ball milling to obtain a specific surface area of ​​300-450 m 2 / kg of modified lithium slag.

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

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

10. The method for preparing the multifunctional coating for the beautiful concrete surface according to any one of claims 1 to 9, characterized in that: The following steps are involved: (1) Carry out base treatment on the concrete surface; (2) Spray the raw materials of the bottom layer on the treated concrete surface, roll on the raw materials of the middle layer after drying, and spray the raw materials of the surface layer after drying.

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