Inorganic sand textured building coating as well as preparation method and application thereof

Abstract

The invention provides an inorganic sand textured building coating and a preparation method and application thereof, and belongs to the technical field of building coatings, the inorganic sand textured building coating comprises 30-50 parts of calcium silicate, 2-30 parts of calcium aluminate, 20-40 parts of a filler, 2-20 parts of calcium carbonate powder, 0.3-13 parts of an additive and 10-40 parts of water. The inorganic sand textured building coating provided by the invention takes an inorganic mineral phase as a main raw material, almost does not release VOC (Volatile Organic Compounds) in production and use processes, is friendly to the environment and human health, and meets the development requirements of green building materials. Through mineralization reaction of mineral phases such as calcium silicate, chemical bonding is formed between the coating and the surface of a matrix, and the adhesive force is remarkably improved; compared with a traditional sand wall coating, the coating is not prone to falling off, and a good decoration effect can be kept for a long time.

Description

Technical Field

[0001] The invention relates to the technical field of architectural coatings, and in particular to an inorganic sand-walled architectural coating and a preparation method and application thereof. Background Art

[0002] As a material widely used in building exterior wall decoration, sand wall paint has the advantages of imitation stone texture and strong decorativeness. However, there are many problems with traditional sand wall paint. At present, most of the sand wall paints on the market use organic emulsions as the main film-forming substances, such as acrylic emulsions. These organic emulsions will release a large amount of volatile organic compounds (VOCs) during production and use, which will cause harm to the environment and human health, and are not in line with the development trend of modern green and environmentally friendly building materials. The weather resistance and durability of organic emulsions after film formation are relatively limited. Under the influence of long-term natural environments such as wind, sun, and rain, they are prone to fading, powdering, and cracking, which affect the beauty and service life of the building exterior wall. The adhesion of traditional sand wall paint to the substrate mainly depends on the bonding effect of organic emulsions. In some special environments or substrate conditions, the adhesion may be insufficient, resulting in the coating falling off. The production process of organic emulsions usually consumes a lot of energy and resources, and its degradation process is slow, which will cause long-term pollution to environmental elements such as soil and water. With the continuous improvement of environmental awareness and the demand for high-performance materials in the construction industry, the development of a green, environmentally friendly, and high-performance inorganic sand wall coating has become an urgent problem to be solved. Summary of the invention

[0003] In view of the technical problems existing in the background technology, the present application provides an inorganic sand-walled architectural coating and a preparation method and application thereof, aiming to solve the technical problems that organic emulsions have insufficient weather resistance and durability and are prone to pollution.

[0004] In a first aspect, an embodiment of the present application provides an inorganic sand-walled building coating, which comprises, by weight, 30 to 50 parts of calcium silicate, 2 to 30 parts of calcium aluminate, 20 to 40 parts of filler, 2 to 20 parts of calcium carbonate powder, 0.3 to 13 parts of additives and 10 to 40 parts of water.

[0005] In some embodiments, the mass ratio of calcium silicate to water is 1:(0.4-0.8).

[0006] In some embodiments, the filler is quartz sand with a particle size ranging from 0.1 to 1.5 mm.

[0007] In some embodiments, the particle size of the calcium carbonate powder is 50 nm to 325 μm, and the calcium carbonate crystal form is calcite.

[0008] In some embodiments, the additives include a dispersant, a thickener, and a water retaining agent in a mass ratio of (0.1-5):(0.1-5):(0.1-3); The water retention agent is at least one of cellulose ether, sodium alginate, and polyvinyl alcohol; The dispersant is at least one of polycarboxylate salts, lignosulfonates, and aminosulfonates; The thickener is at least one of bentonite, fumed silica, and magnesium aluminum silicate.

[0009] In a second aspect, an embodiment of the present application provides a method for preparing an inorganic sand-textured architectural coating, including the following steps: Calcium silicate, calcium aluminate, filler, calcium carbonate powder, dispersant, and water are vigorously stirred at a high speed to obtain a mixed slurry; A thickener and a water retention agent are added to the mixed slurry, and after stirring evenly, an inorganic sand-textured architectural coating is obtained.

[0010] In some embodiments, the inorganic sand-textured architectural coating is stored in a sealed manner.

[0011] In some embodiments, the high-speed stirring speed is 800 - 1500 rpm, and the stirring time is 5 - 30 min.

[0012] In a third aspect, an embodiment of the present application provides a construction method for an inorganic sand-textured architectural coating. The inorganic sand-textured architectural coating is evenly applied to the surface of the substrate by spraying, scraping, or rolling, and after curing, a coating is formed. The number of coating applications is not less than once, the thickness of each coating application is 0.25 - 3 mm, and the time interval between each coating application is not less than 24 h.

[0013] In some embodiments, the construction temperature is -10~50°C, and the relative humidity is 40% - 80%.

[0014] In some embodiments, the natural curing time of the coating is not less than 7 days.

[0015] Different from the prior art solutions, the beneficial effects of the present application include: 1. This application uses calcium silicate as the main reactive mineral phase. Calcium silicate forms a sol-like coating with water. This sol-like component absorbs carbon dioxide in the air, causing calcium silicate to undergo a mineralization reaction with carbon dioxide to form calcium carbonate, which provides strength and adhesion to the coating. At the same time, it has the function of carbon sequestration and environmental protection, effectively replacing the organic emulsions and sols in ordinary coatings without releasing harmful substances. Calcium carbonate powder is also added. Part of the calcium carbonate powder acts as an inert filler during the coating preparation process, and the other part can serve as calcium carbonate nucleation sites during the coating curing stage, reducing the activation energy required for the reaction, thereby accelerating the progress of the calcium silicate mineralization reaction. At the same time, by selecting calcium carbonate powder with a calcite crystal form, it can provide a template for the nucleation of calcium carbonate formed by the reaction of calcium silicate and carbon dioxide in the coating, reducing the activation energy required for it to become the calcite crystal form, making it easier to generate calcite, and further controlling the microscopic morphology of the calcium carbonate formed by the reaction, improving the weather resistance, hardness and other properties of the coating.

[0016] 2. The inorganic sand-textured architectural coating of this application uses inorganic mineral phases as the main raw materials, hardly releases VOCs during production and use, is friendly to the environment and human health, and meets the development requirements of green building materials. Through the mineralization reaction of mineral phases such as calcium silicate, the coating forms chemical bonding with the substrate surface, significantly improving the adhesion. Compared with traditional sand-textured coatings, the coating is not easy to fall off and can maintain a good decorative effect for a long time. The coating can undergo mineralization reactions in different climatic environments. As the reaction progresses, the strength, hardness and durability of the coating continuously improve. The inorganic sand-textured architectural coating of this application can achieve good performance indicators in a short time, and its performance is stable during long-term use, with good weather resistance, water resistance and stain resistance. Components such as quartz sand and calcium carbonate in the coating can provide rich colors and textures, and the stone-like effect is realistic, meeting the decorative needs of different architectural styles. At the same time, due to the stable performance of the coating, the decorative effect is long-lasting and not easy to fade or change color.

[0017] The above description is only an overview of the technical solution of this application. In order to be able to understand the technical means of this application more clearly, it can be implemented in accordance with the content of the specification. And in order to make the above and other purposes, features and advantages of this application more obvious and understandable, the specific embodiments of this application are specifically given below. Detailed Description of the Invention

[0018] The embodiments of the technical solution of this application will be described in detail below. The following embodiments are only used to illustrate the technical solution of this application more clearly, so they are only examples and cannot be used to limit the protection scope of this application.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs; the terms used herein are for the purpose of describing specific embodiments only and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and any variations thereof are intended to cover non-exclusive inclusion.

[0020] In the description of the embodiments of this application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity, specific order, or primary-secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "a plurality" is more than two, unless otherwise specifically defined.

[0021] Referring to "embodiments" herein means that specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of this application. The phrase appears in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0022] In the description of the embodiments of this application, the term "and / or" is merely a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0023] In the description of the embodiments of this application, the term "a plurality" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple sheets" refers to more than two sheets (including two sheets).

[0024] Most of the sand wall coatings on the current market use organic emulsions as the main film-forming substances, such as acrylic emulsions. These organic emulsions will release a large amount of VOCs during production and use, causing harm to the environment and human health, and having limited weather resistance and durability, affecting the beauty and service life of building facades.

[0025] In order to solve the technical problems of poor green environmental protection, high VOC emissions, performance limitations, and insufficient adhesion to the substrate existing in the existing sand wall coatings, this application provides an inorganic sand wall building coating, its preparation method and application. Among them, through the mineralization reaction of mineral phases such as calcium silicate, the coating can quickly form, having not only good decorative performance but also the advantages of green environmental protection, near-zero VOC emissions, fast performance development, durable weather resistance, and high adhesion to the substrate.

[0026] In a first aspect, an inorganic sand-textured architectural coating is provided according to an embodiment of the present application. By mass, it includes 30-50 parts of calcium silicate, 2-30 parts of calcium aluminate, 20-40 parts of filler, 2-20 parts of calcium carbonate powder, 0.3-13 parts of additive, and 10-40 parts of water.

[0027] In the technical solution of the embodiment of the present application, the calcium silicate mineral phase and water form a gelling component, which can absorb carbon dioxide in the air and react with it to generate calcium carbonate, etc. While providing strength and adhesion to the coating, it has the function of carbon fixation and environmental protection, effectively replacing the organic emulsion and sol in ordinary coatings and releasing no harmful substances.

[0028] For the calcium carbonate powder, a part of the calcium carbonate powder acts as an inert filler during the coating preparation process, and another part can act as a calcium carbonate nucleation site during the coating curing stage, reducing the activation energy required for the reaction, thereby accelerating the progress of the calcium silicate mineralization reaction; at the same time, by controlling the crystal form and morphology of the calcium carbonate powder, the microscopic morphology of the calcium carbonate generated by the reaction can be further controlled.

[0029] As a functional mineral phase, calcium aluminate can play a role in adjusting the rheology of the coating and preventing the coating from settling in the coating; at the same time, after being coated on the substrate, calcium aluminate can adjust the setting time of the coating and provide its early strength. Without adding calcium aluminate, the thixotropy of the whole coating will be poor and it is easy to settle; at the same time, the early strength is insufficient and the coating is easy to powder off. When the addition amount is too large, due to the high hydration activity of calcium aluminate, the coating will coagulate prematurely and cannot be effectively coated.

[0030] In some embodiments, the mass ratio of calcium silicate to water is 1:(0.4-0.8).

[0031] In the technical solution of the embodiment of the present application, the ratio of calcium silicate to water is generally 1:(0.4-0.8). Whether the mass fraction of calcium silicate is too large or too small, a sol-like coating cannot be formed. If the mass fraction of calcium silicate in the coating is too large, too much calcium silicate will only act as an unreacted filler, affecting the overall performance; too little calcium silicate cannot form an effective cementitious structure.

[0032] In some embodiments, the filler is quartz sand, and the particle size range is 0.1-1.5 mm.

[0033] In the technical solution of the embodiment of the present application, quartz sand with a moderate particle size is selected as the filler. The quartz sand mainly provides the stone-like texture and roughness of the sand-textured coating, enhancing the decorative effect of the coating.

[0034] In some embodiments, the particle size of the calcium carbonate powder is 50 nm - 325 μm, and the crystal form of the calcium carbonate is calcite.

[0035] In the technical solution of the embodiment of the present application, the crystal form of calcium carbonate is calcite, and the morphology is an aggregate formed by the accumulation of multiple cuboids; during the reaction of calcium silicate in the coating with CO2, the amorphous calcium carbonate formed usually nucleates heterogeneously, and at this time, the calcium carbonate powder added by us can provide a template for nucleation, reducing the activation energy required to form the calcite crystal form, and thus making it easier to generate calcite.

[0036] In some embodiments, the additives include a dispersant, a thickener, and a water retention agent, and their mass ratio is (0.1~5):(0.1~5):(0.1~3); The water retention agent is at least one of cellulose ether, sodium alginate, and polyvinyl alcohol; The dispersant is at least one of polycarboxylate salts, lignosulfonates, and aminosulfonates; The thickener is at least one of bentonite, fumed silica, and magnesium aluminum silicate.

[0037] In the technical solution of the embodiment of the present application, the additives include a dispersant, a thickener, and a water retention agent. A dispersant suitable for the inorganic system is selected, such as a polycarboxylate salt dispersant. Its function is to uniformly disperse various solid particles in the coating, prevent agglomeration, and ensure the stability and construction performance of the coating. An inorganic thickener, such as bentonite, etc., is used. The thickener can adjust the viscosity of the coating, making it have good rheology during the construction process and preventing sagging and dripping. A cellulose ether water retention agent is selected. The water retention agent helps to keep the moisture in the coating, prevent the moisture from evaporating too quickly, and ensure that the mineralization reaction proceeds under suitable humidity conditions.

[0038] In a second aspect, the embodiment of the present application provides a preparation method of an inorganic sand-textured architectural coating, including the following steps: High-speed stirring of calcium silicate, calcium aluminate, filler, calcium carbonate powder, dispersant, and water to obtain a mixed slurry; Adding a thickener and a water retention agent to the mixed slurry, and stirring evenly to obtain an inorganic sand-textured architectural coating.

[0039] In some embodiments, the inorganic sand-textured architectural coating is stored in a sealed manner.

[0040] In some embodiments, the high-speed stirring speed is 800~1500 rpm, and the stirring time is 5~30 min.

[0041] In the technical solution of the embodiment of the present application, solid powder raw materials such as calcium silicate, quartz sand, and calcium carbonate powder are added to a high-speed mixer together with a dispersant and part of water, and stirred at a speed of 800 - 1500 rpm for 5 - 30 minutes to fully disperse the solid particles evenly and form a uniform slurry. Under the stirring state, a thickener and a water retention agent are slowly added, and stirring is continued for 5 - 15 minutes to make the coating reach a suitable viscosity and rheological properties. Then, according to the actual state of the coating, an appropriate amount of the remaining water is added to adjust the solid content and construction performance of the coating. The prepared inorganic sand wall coating is filled into a sealed container to avoid long-term contact with air and prevent the carbonation reaction between carbon dioxide and the coating from affecting the effect. The coating should be stored in a cool and dry environment, and the shelf life is 6 - 12 months.

[0042] In a third aspect, the embodiment of the present application provides a construction method of an inorganic sand wall-like architectural coating. The inorganic sand wall-like architectural coating is evenly coated on the surface of the substrate by spraying, scraping, or rolling, and a coating is formed after curing. The number of coating times is not less than once, and the coating thickness each time is 0.25 - 3 mm, and the time interval between each coating is not less than 24 h.

[0043] In some embodiments, the construction temperature is -10~50°C, and the relative humidity is 40% - 80%.

[0044] In some embodiments, the natural curing time of the coating is not less than 7 days.

[0045] In the technical solution of the embodiment of the present application, the substrate is pretreated before construction: the surface of the building substrate to be coated is cleaned to remove impurities such as dust, oil stains, and loose substances on the surface, and ensure that the surface of the substrate is flat and firm. For substrates with strong water absorption, such as concrete walls, they can be pre-wetted by spraying water, but there should be no obvious accumulated water on the surface.

[0046] The inorganic sand wall coating is evenly coated on the surface of the substrate by spraying, scraping, or rolling, etc. The construction thickness is controlled at 0.25 - 3 mm. Multiple coatings can be carried out according to the design requirements and decorative effects, and the time interval between each coating is not less than 24 h. During the construction process, the environmental temperature should be maintained at -10 to 50°C, and the relative humidity should be maintained at 40% - 80% to promote the smooth progress of the carbonation reaction of the coating. After the construction is completed, the coating is cured and maintained in the natural environment. During the maintenance process, the mineral phases such as calcium silicate in the coating will react with carbon dioxide in the air to generate calcium carbonate crystals, filling the internal pores of the coating and improving the strength, hardness, and adhesion of the coating. The natural curing time is not less than 7 days, and the coating should be avoided from being collided by external forces and soaked by water during this period.

[0047] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and should not be construed as a limitation to the present application. For those embodiments where specific technologies or conditions are not indicated, the technologies or conditions described in the literature in this field or according to the product specifications are followed. For reagents or instruments whose manufacturers are not indicated, they are all conventional products that can be obtained through commercial purchases.

[0048] I. Preparation Method Example 1 A preparation method of an inorganic sand-textured architectural coating includes the following steps: Weigh the raw materials according to the following mass parts: 30 parts of calcium silicate, 21 parts of quartz sand, 15 parts of calcium carbonate powder, 15 parts of calcium aluminate, 1 part of polycarboxylate sodium salt dispersant, 2 parts of bentonite thickener, 0.5 part of cellulose ether water retainer, and 15.5 parts of water.

[0049] Add 30 parts of calcium silicate, 21 parts of quartz sand, 15 parts of calcium carbonate powder, 15 parts of calcium aluminate, the dispersant and water into a high-speed mixer, and stir at a speed of 800 rpm for 30 minutes to fully disperse the solid particles evenly to form a uniform slurry. Under the stirring state, slowly add 2 parts of bentonite thickener and 0.5 part of cellulose ether water retainer, and continue to stir for 15 minutes to obtain the inorganic sand-textured architectural coating.

[0050] Example 2 The difference between Example 2 and Example 1 is that the raw materials are weighed according to the following mass parts: 30 parts of calcium silicate, 30.5 parts of quartz sand, 13 parts of calcium carbonate powder, 10 parts of calcium aluminate, 1.2 parts of polycarboxylate sodium salt dispersant, 2.5 parts of bentonite thickener, 0.8 part of cellulose ether water retainer, and 12 parts of water.

[0051] The preparation method is the same as that of Example 1.

[0052] Example 3 The difference between Example 3 and Example 1 is that the raw materials are weighed according to the following mass parts: 45 parts of calcium silicate, 20 parts of quartz sand, 6 parts of calcium carbonate powder, 5 parts of calcium aluminate, 0.8 part of polycarboxylate sodium salt dispersant, 1.8 parts of bentonite thickener, 0.6 part of cellulose ether water retainer, and 20.8 parts of water.

[0053] The preparation method is the same as that of Example 1.

[0054] Comparative Example 1 The difference between Comparative Example 1 and Example 1 lies in that raw materials are weighed according to the following parts by mass: 30 parts of calcium silicate, 21 parts of quartz sand, 15 parts of calcium carbonate powder, 15 parts of calcium aluminate, 1 part of polycarboxylate sodium salt dispersant, 2 parts of bentonite thickener, 0.5 part of cellulose ether water retention agent, and 10 parts of water.

[0055] Comparative Example 2 The difference between Comparative Example 2 and Example 1 lies in that raw materials are weighed according to the following parts by mass: 30 parts of calcium silicate, 21 parts of quartz sand, 15 parts of calcium carbonate powder, 15 parts of calcium aluminate, 1 part of polycarboxylate sodium salt dispersant, 2 parts of bentonite thickener, 0.5 part of cellulose ether water retention agent, and 25 parts of water.

[0056] Comparative Example 3 The difference between Comparative Example 3 and Example 1 lies in that raw materials are weighed according to the following parts by mass: 30 parts of calcium silicate, 21 parts of quartz sand, 15 parts of calcium aluminate, 1 part of polycarboxylate sodium salt dispersant, 2 parts of bentonite thickener, 0.5 part of cellulose ether water retention agent, and 15.5 parts of water. Calcium carbonate powder is not added.

[0057] Comparative Example 4 The difference between Comparative Example 4 and Example 1 lies in that raw materials are weighed according to the following parts by mass: 30 parts of calcium silicate, 21 parts of quartz sand, 1 part of polycarboxylate sodium salt dispersant, 2 parts of bentonite thickener, 0.5 part of cellulose ether water retention agent, and 15.5 parts of water. Calcium aluminate is not added.

[0058] Comparative Example 5 The difference between Comparative Example 4 and Example 1 lies in that raw materials are weighed according to the following parts by mass: 30 parts of calcium silicate, 21 parts of quartz sand, 15 parts of calcium carbonate powder, 15 parts of calcium aluminate, 1 part of polycarboxylate sodium salt dispersant, 2 parts of bentonite thickener, and 15.5 parts of water.

[0059] II. Test Methods 1. Adhesion test: The adhesion of the coating on the concrete substrate is tested by the cross-cut method. The adhesion grade is divided into 0 - 5 levels. The larger the level number, the worse the adhesion; level 0 has the best adhesion, the coating has no peeling or separation at all, and the cutting edge is completely smooth; when the peeling area exceeds 65%, the adhesion is the worst.

[0060] 2. VOC emission test: The VOC content of the coating is detected according to the standard method of GB 24408 - 2009.

[0061] 3. Weather resistance test: The sample plates coated with the coating are placed in the outdoor natural environment for 12 months, and the appearance changes of the sample plates are observed.

[0062] 4. Hardness development test: After the coating is cured and maintained for 7 days, the hardness of the coating is tested by the pencil method.

[0063] 5. Coating pot life test: After the coating is prepared, it is placed at 25 °C for observation to check for sedimentation. At the same time, the fluidity of the coating is tested initially and after 5 hours of pot life using the flow cup method (No. 4 cup).

[0064] III. Analysis of test results of each example and comparative example The properties of the coatings prepared in each example and comparative example are tested, and the test results are shown in Table 1 below.

[0065] Table 1 Test results of coating properties prepared in each example and comparative example

[0066] As can be seen from Table 1, the inorganic sand-textured architectural coatings prepared in Examples 1-3 exhibit good adhesion (adhesion grade 0), near-zero VOC emissions, excellent weather resistance (color retention rate above 93%), and rapid property development. The performance indicators such as adhesion, VOC emissions, weather resistance, and hardness of the coatings prepared in Examples 1-3 are quite comparable, indicating that the coating formulation of the present invention has good stability and repeatability, and adjusting the raw material ratio within a certain range will not have a significant impact on the main properties of the coating.

[0067] It can be seen from Comparative Example 1 and Comparative Example 2 that the weight ratio of water to calcium silicate needs to be between 0.4 and 0.8. Too little water will cause the coating viscosity to be too high, and conversely, too much water will cause the viscosity to be too low; at the same time, when the water content is not within the range, the reaction degree will also decrease, resulting in a decrease in adhesion.

[0068] It can be seen from Comparative Example 3 that calcium carbonate powder plays a role in increasing the reaction rate in the coating system. After removing the calcium carbonate powder, the reaction degree of the coating within the same curing time is lower, and the adhesion decreases.

[0069] It can be seen from Comparative Example 4 that without adding calcium aluminate, the coating is prone to sedimentation, resulting in the coating not meeting the requirement of a pot life greater than 5 hours.

[0070] It can be seen from Comparative Example 5 that without adding a water retention agent, the coating is prone to water loss, resulting in an increase in viscosity after 5 hours of pot life and sedimentation at the same time.

[0071] It should be noted that this application is not limited to the above embodiments. The above embodiments are only examples, and embodiments having the same constitution in essence as the technical idea and achieving the same effect within the scope of the technical solution of this application are all included in the technical scope of this application. In addition, within the scope not departing from the gist of this application, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways constructed by combining some constituent elements in the embodiments are also included in the scope of this application.

Claims

1. An inorganic sand-walled architectural coating, characterized in that: Calculated by mass, it comprises 30-50 parts of calcium silicate, 2-30 parts of calcium aluminate, 20-40 parts of filler, 2-20 parts of calcium carbonate powder, 0.3-13 parts of additives and 10-40 parts of water.

2. The inorganic sand-walled architectural coating according to claim 1, characterized in that: The mass ratio of the calcium silicate to water is 1:(0.4-0.8).

3. The inorganic sand-walled architectural coating according to claim 1, characterized in that: The filler is quartz sand with a particle size ranging from 0.1 to 1.5 mm.

4. The inorganic sand-walled architectural coating according to claim 1, characterized in that: The particle size of the calcium carbonate powder is 50nm-325μm, and the calcium carbonate crystal form is calcite.

5. The inorganic sand-walled architectural paint according to claim 1, characterized in that: The additives include a dispersant, a thickener and a water retaining agent, and the mass ratio thereof is (0.1-5):(0.1-5):(0.1-3); The water retaining agent is at least one of cellulose ether, sodium alginate and polyvinyl alcohol; The dispersant is at least one of polycarboxylate sodium salt, lignin sulfonate, and aminosulfonate; The thickener is at least one of bentonite, fumed silica, and magnesium aluminum silicate.

6. A method for preparing an inorganic sand-walled architectural coating as claimed in any one of claims 1 to 5, characterized in that: The steps include: Mixing calcium silicate, calcium aluminate, filler, calcium carbonate powder, dispersant and water to obtain a mixed slurry; Add a thickener and a water retaining agent into the mixed slurry, stir evenly to obtain an inorganic sand wall-like building paint.

7. The method for preparing an inorganic sand-walled architectural coating according to claim 6, characterized in that: The inorganic sand-wall-like building paint is sealed and stored.

8. The method for preparing an inorganic sand-walled architectural coating according to claim 6, characterized in that: The stirring speed is 800-1500 rpm, and the stirring time is 5-30 min.

9. A construction method for an inorganic sand-walled architectural coating as claimed in any one of claims 1 to 5, characterized in that: The inorganic sand-walled architectural paint is uniformly applied on the surface of the substrate by spraying, scraping or rolling, and a coating is formed after curing. The coating is applied at least once, the coating thickness is 0.25 to 3 mm each time, and the time interval between each coating is not less than 24 hours.

10. The construction method of an inorganic sand-walled architectural coating according to claim 9, characterized in that: The construction temperature is -10~50℃, and the relative humidity is 40%~80%; the natural curing time of the coating is not less than 7d.

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