Protective coatings and protective treatment methods for reusable formwork

Abstract

This invention discloses a protective coating and treatment method for reusable formwork, belonging to the field of building concrete. This invention combines the advantages of 3D-printed concrete and traditional formwork, aiming to solve the problem of adhesion between new and old concrete during demolding after wall pouring and hardening. The protective coating used is a polyurethane composite reinforced coating, which forms a dense film structure through penetration and chemical reaction, increasing the surface hardness of the formwork and reducing adhesion to concrete, significantly improving demolding smoothness. The protective treatment method of this invention increases the number of formwork reuses and service life, and has significant engineering application prospects. Multi-layer treatment reduces the use of release agents while protecting the formwork from wear, and is suitable for various formwork materials, improving the efficiency and economy of building construction.

Description

Technical Field

[0001] This invention relates to the field of building concrete technology, and more specifically, to protective coatings and protective treatment methods for reusable formwork. Background Technology

[0002] As people's living standards improve, they increasingly demand that buildings, while fulfilling their functional requirements, also possess artistic and aesthetic qualities. The application of complex shapes in architecture will become increasingly widespread. These complex shapes and types are numerous, such as irregular columns (variable cross-section columns, curved columns, etc.), irregular beams (curved beams, variable cross-section beams, etc.), and irregular panels (curved panels, honeycomb panels, etc.). Currently, there are two common implementation schemes for these irregular structures. One is to directly print the irregular structure using 3D printing technology. This scheme easily achieves irregular shapes and decorative effects, but in practice, due to weak interlayer bonding, the printed templates are unsuitable for load-bearing components, and demolding is difficult, making them unusable. The second scheme is to use specialized reusable modular templates. Currently, most common reusable irregular templates are made of wood, steel, or plastic. These templates have the advantages of easy demolding, high surface flatness, and the ability to achieve simple irregular shapes, but the process of creating decorative effects is complex, costly, and the decorative effect is poor. Therefore, how to utilize 3D printing technology to achieve reusable templates is of great significance.

[0003] Patent CN117645824A discloses a coating for the surface of 3D printed parts. This coating is a liquid coating suitable for surface treatment of 3D printed parts, based on epoxy resin and talc powder, combined with auxiliary agents such as silica and calcium carbonate. After the coating is applied and solidified, it can effectively cover the texture of the printed parts, while also smoothing the parts and improving their mechanical properties and weather resistance. However, this coating makes it difficult to recycle 3D printing templates. Concrete needs to be poured inside the template during use, and the difficulty in removing the 3D printing template makes it impossible to achieve reusability. Summary of the Invention

[0004] 1. The technical problem that the invention aims to solve

[0005] To address the difficulty in achieving reusability of 3D printed templates in existing technologies, this invention aims to provide a protective coating and treatment method for reusable templates. By spraying the protective coating onto the surface of the 3D printed template, it helps prevent adhesion between the template and the cast-in-place wall during demolding and minimizes damage to both the template and the wall, thereby enabling the 3D printed template to be reused. This protective coating and treatment method can also be applied to other types of templates, such as wooden templates and plastic templates, further improving their reusability.

[0006] 2. Technical Solution

[0007] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0008] The protective coating for reusable templates of the present invention comprises the following components in parts by weight:

[0009] Nano-alumina: 18-26 parts by weight, and in practice, 18 parts by weight, 20 parts by weight, 25 parts by weight, 26 parts by weight, etc. can be used;

[0010] Nano silicon carbide powder: 13-21 parts by weight, and in practice, 13 parts by weight, 15 parts by weight, 18 parts by weight, 21 parts by weight, etc. can be used;

[0011] Rare earth oxides: 1 to 3 parts by mass, in practice, 1 part by mass, 2 parts by mass, 3 parts by mass, etc. can be used;

[0012] Epoxy resin: 58-65 parts by weight, in practice, 58 parts by weight, 60 parts by weight, 63 parts by weight, 65 parts by weight, etc. can be used;

[0013] Dispersant: 0.5-0.9 parts by weight, in practice, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.9 parts by weight, etc. can be used;

[0014] Polyether polyol: 70-75 parts by weight, in practice, 70 parts by weight, 72 parts by weight, 73 parts by weight, 75 parts by weight, etc. can be used;

[0015] Micronized powder: 5-7 parts by weight, in practice, 5 parts by weight, 6 parts by weight, 6.5 parts by weight, 7 parts by weight, etc. can be used;

[0016] Plasticizer: 2-5 parts by weight, in practice, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, etc. can be used;

[0017] Curing agent: 0.9 to 1.6 parts by weight, in practice, 0.9 parts by weight, 1.0 parts by weight, 1.5 parts by weight, 1.6 parts by weight, etc. can be used;

[0018] Accelerator: 2-3 parts by weight, in practice, 2 parts by weight, 2.3 parts by weight, 2.5 parts by weight, 3 parts by weight, etc. can be used;

[0019] Additives: 8-12 parts by weight. In practice, 8, 10, 11, or 12 parts by weight can be used.

[0020] Furthermore, the rare earth oxide is Er2O3; and / or the dispersant is sodium polyacrylate; and / or the plasticizer is xylene phosphate; and / or the curing agent is vinyltriamine; and / or the coagulant is calcium aluminate; and / or the additive is non-tar pitch.

[0021] Furthermore, the average particle size of the nano-alumina is 60–70 nm; or / and the average particle size of the nano-silicon carbide is 45–55 nm; or / and the epoxy resin density is 1.1–1.3 g / cm³. 3 The viscosity is 7500–8000 Pa·s; or / and the powder is silicon carbide powder with an average particle size of 25–30 nm and a specific surface area of ​​80–100 m². 2 / g, density is 3.6~3.9g / cm³ 3 .

[0022] The present invention also provides a protective treatment method for reusable templates, which involves spraying the protective coating as described above onto the template surface.

[0023] Furthermore, it includes the following processes:

[0024] S1. After the template is made, clean the template surface and apply a layer of water-based primer to the template surface;

[0025] S2. Spray protective coating on the template surface.

[0026] Furthermore, in step S2, carboxymethyl cellulose is added as a viscosity modifier during the application of the protective coating. The amount of carboxymethyl cellulose used is 2.5% to 3% of the total weight of the coating. In practice, 2.5%, 2.8%, 3%, etc. can be used.

[0027] Furthermore, the protective coating in step S2 shall be sprayed no less than three times, such as three to five times, with an interval of no less than 3 hours, such as 3 to 4 hours between two sprays, and the thickness of each spray shall be no less than 0.03 mm, such as 0.03-0.05 mm.

[0028] Furthermore, in step S1, after the template is completed, the vertical strip edge on the inner side of the template is cut to form a wedge-shaped protrusion on the inner side, and then the template surface is cleaned.

[0029] Furthermore, in step S1, after applying a water-based primer to the template surface, the template surface is roughened, and then a protective coating is sprayed on.

[0030] Furthermore, after the spraying in step S2 is completed, a lubricating isolation layer is brushed onto the surface of the template. That is, after the interface layer has formed a film, before the wall is poured, machine oil is evenly brushed onto the interface layer on the inner surface of the template, and the machine oil completely covers the interface layer.

[0031] It should be noted that surface treatment technology for templates is one of the challenges in producing 3D printed reusable templates. Currently, the commonly used template demolding method in the industry is to apply a release agent to the template surface. Types of release agents include pure oil-based release agents, emulsified oil-based release agents, saponified oil-based release agents, paraffin-based release agents, chemically active release agents, synthetic resin-based release agents, and other types. When demolding templates, these release agents work through chemical and physical lubrication mechanisms. The chemical action involves the organic acids in the release agent reacting with alkaline substances on the template surface to form a thin film that is not easily adhered to, thereby reducing the adhesion between the concrete and the template and achieving the demolding effect. The physical lubrication effect involves the release agent making the concrete surface smoother, reducing the contact area between the template and the concrete surface, thereby reducing friction and facilitating demolding.

[0032] Since both 3D-printed concrete formwork and cast-in-place walls are made of concrete, common release agents exhibit similar adhesion to both materials during the chemical reaction. Furthermore, the porous structure of 3D-printed concrete causes the release agent to seep into the formwork, rendering it ineffective. This leads to adhesion between the old and new concrete during demolding, making demolding difficult and severely impacting the formwork's reusability and usability. In addition, 3D-printed reusable formwork shares the same problem as common reusable formwork such as plastic and wooden templates: during transportation and handling, the formwork is prone to bumps and scratches, resulting in chipped edges and significantly reducing its reusability. This further limits the reusability of 3D-printed formwork.

[0033] The protective coating provided by this invention helps to alleviate the above situation. The developed protective coating is a polyurethane composite reinforced coating. After being applied to the template surface, it can undergo a hydration reaction with water molecules on the template surface to form a polyester acid compound. This compound penetrates into the micropores of the concrete surface and is tightly connected to the concrete template surface by molecular bonds. As the interface forms, the water molecules on the coating surface continuously decrease and accumulate tightly on the template surface and in the pores. At the same time, Ca(OH)2 produced by cement hydration in the template reacts with the urethane groups in the polymer to form urethane metal salts, which are tightly connected to the polymer by ionic bonds, forming a connected film structure of a certain thickness. The film is tightly connected to the pores on the template surface and interpenetrates each other. The product and aggregate are mutually bonded, ultimately forming a dense coating film that is tightly connected to the template. The micro powder added to the coating can effectively fill the pores on the material surface caused by the concrete printing production method, increase the hydration reaction sites, facilitate the connection between the coating film and the template, form a template connection reinforcement layer, further enhance the hardness of the template surface, and prevent template damage during transportation and demolding. After the reaction on the template surface is completed, due to intermolecular forces and the addition of lubricating components, the unreacted macromolecular polymers in the coating aggregate outward and connect with each other to form a smooth and dense polymer layer. This reduces the direct contact between the concrete surface and the mold, lowers the adhesion force, and forms a release layer that is more conducive to demolding. When casting the wall, since the reaction inside the coating has ended, it is difficult for hydration reaction to occur again. Therefore, the connection strength between the interface layer and the template is greater than the connection strength with the wall. Thus, the interface between the interface layer and the wall is a weak interface during demolding and is easily damaged, which facilitates demolding. In addition, the film structure generated by the reaction can prevent water molecules from entering the interior of the template and causing a decline in template performance, thus avoiding affecting its turnover rate and the quality of the formed wall.

[0034] 3. Beneficial effects

[0035] Compared with the prior art, the technical solution provided by this invention has the following advantages:

[0036] (1) The protective coating for reusable templates of the present invention can generate a dense film structure near the concrete base layer, effectively improving the hardness of the template surface and preventing damage to the template during transportation and demolding. A dense and smooth polymer film structure is generated on the outside, reducing the direct contact between the concrete surface and the template, reducing the adhesion force and the bonding strength between the old and new concrete interfaces, and helping to reduce the friction between the concrete and the template, so that the wall can be demolded smoothly without damaging the template surface. The realization of this dual function makes the composite coating have a wide range of application prospects in the construction and engineering fields, enabling the reusable use of 3D printed templates. The coating is also applicable to other types such as wooden templates and plastic templates, further increasing the number of templates that can be reused.

[0037] (2) Conventional reusable templates, such as wooden templates and steel templates, involve directly applying a release agent to the template surface during demolding, using vibration to promote separation of the template from the wall, and using a pry bar to pry the template edge until the template is completely separated from the wall. This can lead to a reduction in the smoothness of the template surface or damage to the surface, affecting the subsequent use of the template. However, the protective treatment method for reusable templates of the present invention can form a film structure with a certain thickness on the template surface, which will not damage the template surface during demolding and increases the number of times the template can be reused.

[0038] (3) The protective treatment method of the reusable template of the present invention can make the template surface hydrophobic, prevent water from entering the template during use and causing the template performance to decrease, and avoid affecting the service life of the template. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the wedge-shaped protrusion on the inner side of the template in an embodiment of the present invention;

[0040] Figure 2 This is a process flow diagram of the protective treatment method in an embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of multi-level protection on the template surface in an embodiment of the present invention;

[0042] Figure 4 This is a schematic diagram illustrating the mechanism of action of the protective coating in this embodiment of the invention;

[0043] Figure 5 This is a schematic diagram of the wall after the template surface treatment and after demolding in the embodiment. Detailed Implementation

[0044] To further understand the content of this invention, a detailed description of the invention will be provided in conjunction with the accompanying drawings.

[0045] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0046] The present invention will be further described below with reference to embodiments.

[0047] Example 1

[0048] Combination Figures 1-5As shown, the reusable template protective coating provided in this embodiment can be called a polyurethane composite reinforced coating. It is made by mixing component A and component B. The main materials used in component A are nano-alumina and nano-silicon carbide powder, with a small amount of rare earth oxide Er2O3 added. Epoxy resin is used as the matrix, and sodium polyacrylate is added as a dispersant. The main material of component B is polyether polyol, with added micro powder, plasticizer, curing agent, accelerator, and additives. The plasticizer is xylene phosphate, the curing agent is vinyltriamine, the main component of the accelerator is calcium aluminate, and the additive is non-tar pitch. Specifically, the polyurethane composite reinforced coating in this embodiment includes: 18 parts by weight of nano-alumina; 15 parts by weight of nano-silicon carbide powder; 1 part by weight of rare earth oxide; 58 parts by weight of epoxy resin; 0.6 parts by weight of dispersant; 72 parts by weight of polyether polyol; 5 parts by weight of micro powder; 2 parts by weight of plasticizer; 1.0 part by weight of curing agent; 2 parts by weight of accelerator; and 8 parts by weight of additives.

[0049] This embodiment also provides a multi-level protective treatment method for reusable templates, namely, spraying the above-mentioned protective coating. Specifically, after the template is made, the template surface is first cleaned and a layer of water-based primer is applied to the template surface; then the above-mentioned protective coating is sprayed on the template surface.

[0050] Taking a 3D printed template scenario as an example, after the template is printed, the inner surface of the template can be ground smooth to avoid the 3D printed strips affecting the flatness of the wall. After printing, a plastic film is covered on the template surface and cured at room temperature for seven days. After the template hardens, a polishing machine is used to grind and cut the inner surface of the template again. A smart CNC cutting device is used to cut the edges of the vertical strips with decorative effects on the inner side of the template, so that the inner protrusion changes from a vertical protrusion to a wedge-shaped protrusion. The chamfer angle can be set in advance to be inclined from 15° to 80°. A CNC cutting machine is used for precise cutting to prevent the material interlocking phenomenon between the newly poured wall and the 3D printed concrete template during wall pouring, which would lead to demolding difficulties. Then, the surface of the 3D printed concrete template is cleaned. A flexible brush is used to clean the cement residue on the inner and outer surfaces of the template to prevent it from affecting the adhesion of the interface agent and hardener on the surface. Then, a layer of water-based primer is applied to the template surface to initially seal the voids on the template surface. The water-based primer used in this embodiment can be one of many commonly available water-based primer products in the industry. Its basic components are resin, added filler, leveling agent, and dispersant. The resin can be one or more of acrylic resin, polyurethane resin, and epoxy resin; the filler can be silicate and quartz sand; the leveling agent is an organosilicon leveling agent; and the dispersant's main component is polyvinyl alcohol, etc. This is a conventional technology product on the market and will not be elaborated further. After applying the water-based primer, a low-temperature plasma generator is used to roughen the template surface to enhance the adhesion of subsequent coatings.

[0051] Specifically, after the template surface is roughened, in this embodiment, a polyurethane composite reinforcing coating is sprayed onto the template surface. A low-pressure spray gun is used to evenly spray the coating onto the template surface, ensuring complete coverage. The reinforcing coating is applied three times, with a 3-hour interval between each application, and each application is 0.03 mm thick. Carboxymethyl cellulose is added as a viscosity modifier during spraying, at a dosage of 3% of the total coating weight. The coating is atomized using compressed air and then sprayed out as a mist, evenly covering the outer surface of the template. To achieve a better atomization effect, the spray gun power should be above 20 kW. After the interface layer has formed, before pouring the wall, machine oil is continuously and evenly brushed onto the inner surface of the template interface layer using a roller or flexible brush as a lubricating and isolating layer. This ensures the machine oil completely covers the interface layer, providing lubrication and isolation, facilitating subsequent template demolding. Finally, cure for three days at 20℃~30℃. During the curing process, ensure good ventilation in the coated area and avoid contact with dust, oil, and other contaminants to prevent affecting the final effect. After the coating is cured, it is easy to demold the template and can significantly improve the surface hardness and wear resistance of the template.

[0052] Example 2

[0053] The protective treatment method for reusable templates provided in this embodiment is basically the same as in Embodiment 1, except that the polyurethane composite reinforced coating used in this embodiment includes: 22 parts by weight of nano-alumina; 21 parts by weight of nano-silicon carbide powder; 2 parts by weight of rare earth oxides; 62 parts by weight of epoxy resin; 0.5 parts by weight of dispersant; 75 parts by weight of polyether polyol; 7 parts by weight of micro powder; 4 parts by weight of plasticizer; 1.5 parts by weight of curing agent; 2 parts by weight of accelerator; and 12 parts by weight of additives. The above protective coating is sprayed four times, with an interval of 3.5 hours between each application. Each application is 0.04 mm thick, and carboxymethyl cellulose is added at a rate of 2.5% of the total weight of the coating during spraying.

[0054] Example 3

[0055] The protective treatment method for reusable templates provided in this embodiment is basically the same as in Embodiment 1, except that the polyurethane composite reinforced coating used in this embodiment includes: 26 parts by weight of nano-alumina; 21 parts by weight of nano-silicon carbide powder; 3 parts by weight of rare earth oxides; 65 parts by weight of epoxy resin; 0.9 parts by weight of dispersant; 70 parts by weight of polyether polyol; 5 parts by weight of micro powder; 5 parts by weight of plasticizer; 1.6 parts by weight of curing agent; 3 parts by weight of accelerator; and 8 parts by weight of additives. The above protective coating is sprayed five times, with a 3-hour interval between each application. Each application is 0.035 mm thick, and carboxymethyl cellulose is added at a rate of 2.6% of the total weight of the coating during spraying.

[0056] Example 4

[0057] The protective treatment method for reusable templates provided in this embodiment is basically the same as that in Embodiment 1. The difference is that the polyurethane composite reinforced coating used in this embodiment includes: 19 parts by weight of nano-alumina; 13 parts by weight of nano-silicon carbide powder; 1 part by weight of rare earth oxide; 60 parts by weight of epoxy resin; 0.5 parts by weight of dispersant; 73 parts by weight of polyether polyol; 6 parts by weight of micro powder; 2 parts by weight of plasticizer; 0.9 parts by weight of curing agent; 2 parts by weight of coagulating agent; and 12 parts by weight of additives.

[0058] Comparative Example 1

[0059] The protective treatment method for reusable templates provided in this comparative example is basically the same as that in Example 1 above. The difference is that the protective coating used in this comparative example only contains component A, that is, it only contains: the main materials are nano-alumina and nano-silicon carbide powder, and a small amount of rare earth oxide Er2O3 is added. Epoxy resin is used as the matrix, and sodium polyacrylate is added as a dispersant. The content of each component is the same as that in Example 1 above.

[0060] Comparative Example 2

[0061] The protective treatment method for the reusable template provided in this comparative example is basically the same as the above embodiments. The difference is that the protective coating used in this comparative example only contains component B, that is: the main material is polyether polyol, plus micro powder, plasticizer, curing agent, accelerator and additives. The plasticizer is xylene phosphate, the curing agent is vinyltriamine, the main component of the accelerator is calcium aluminate, and the additive is non-tar pitch. The content of each component is the same as in Example 1 above.

[0062] Comparative Example 3

[0063] The protective treatment method for reusable templates provided in this comparative example is basically the same as the above embodiments. The difference is that the protective coating in the embodiments is not used in this comparative example. Instead, machine oil, which is commonly used in template engineering, is selected as the release agent for the interface agent on the inner surface of the template.

[0064] In practice, the bonding performance test method between concrete formwork and walls is used to test the effect of surface agents on demolding performance, and the following steps are followed:

[0065] I. Preparation of New and Old Concrete Specimens: The bonding performance between the formwork and the wall can be approximated as the bonding performance between new and old concrete. Specimens were prepared using 100mm×100mm×100mm plastic molds, in two parts. First, 50mm of old concrete was poured. At the interface, a grooving method was used to simulate different roughnesses in actual conditions. The roughness of the bonding interface was controlled and evaluated using a roughness index. After 7 days of curing, the old concrete underwent surface treatment. After treatment, new concrete was poured, vibrated, and then covered with plastic film for static curing.

[0066] II. The splitting tensile strength test was used to test the bond strength between new and old concrete. The experiment was conducted according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T50081-2019). The specific loading process is as follows: ① Before loading the specimen, clean the upper and lower loading plates of the pressure testing machine. Draw a parallel line between the upper and lower surfaces of the bonded specimen to determine the loading position. ② Place the specimen in the splitting clamp. First, remove the upper steel pad, place the plywood pad at the bottom center of the pad, lift the bottom of the specimen with both hands, and center the specimen. Then, reinsert the upper steel pad. Place the specimen with the clamp in the center of the lower plate of the pressure testing machine, ensuring that the upper and lower pads are aligned with the line drawn on the specimen surface. ③ Start the pressure testing machine. During loading, ensure that the clamp fits snugly against the upper and lower plates of the pressure testing machine. Control the loading speed to 0.04–0.08 MPa / s. The loading speed must be continuous and uniform to avoid large errors. Record the load at which the specimen fails, and calculate the splitting tensile strength of the bonded specimen between the old and new concrete.

[0067] In practice, the surface hardness test method for templates is used to test the effect of nano-ceramic coatings on the surface hardness of templates. The following steps are followed:

[0068] The surface hardness of each embodiment was measured using a Shore hardness tester. Before use, the pointer of the hardness tester was zeroed. Then, the needle was pressed vertically and at a constant speed until the end face of the hardness tester needle was in complete contact with the surface of the sample. The measured value on the dial of the hardness tester was recorded. The average value of three different positions was taken as the hardness of the template surface.

[0069] The splitting tensile strength of the joint surfaces in each case is shown in Table 1 below, and the surface hardness of each template is shown in Table 2 below.

[0070] Table 1: Splitting tensile strength of each template connection surface

[0071]

[0072] Table 2: Surface Hardness of Each Template

[0073] Example 1 87 Example 2 91 Example 3 92 Example 4 89 Comparative Example 1 63 Comparative Example 2 77 Comparative Example 3 52

[0074] As shown in Table 1, the use of polyurethane composite coating can significantly reduce the interfacial bond strength between the finished and unfinished areas of the template. Compared with the addition of component A alone, the splitting tensile strength of the mixed coating is reduced by 100% and 76%, respectively. Compared with the addition of component B alone, the splitting tensile strength is reduced by 100% and 80%, respectively. Compared with the use of conventional release agent, the splitting tensile strength is reduced by 100% and 86%, respectively. This indicates that the composite coating has good applicability for the demolding of 3D printed reusable templates and can achieve smooth demolding of the template.

[0075] As can be seen from Table 2, the polyurethane composite coating in the embodiments of the present invention can significantly improve the surface hardness of the template. Compared with adding only component A, the surface hardness is increased by 39%, compared with adding only component B, the surface hardness is increased by 15%, and compared with using conventional release agents, the surface hardness is increased by 69%.

[0076] The present invention and its embodiments have been described above illustratively. This description is not restrictive and is merely one embodiment of the present invention, and is not actually limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A protective coating for reusable templates, characterized in that: The components include the following parts by weight: Nano-alumina: 18-26 parts by weight Nano silicon carbide powder: 13~21 parts by weight, the average particle size of the nano silicon carbide powder is 45~55nm; Rare earth oxides: 1-3 parts by mass Epoxy resin: 58-65 parts by weight Dispersant: 0.5~0.9 parts by weight Polyether polyol: 70-75 parts by weight Silicon carbide powder: 5 to 7 parts by mass, average particle diameter of silicon carbide powder is 25 to 30 nm, specific surface area is 80 to 100 m 2 / g, density is 3.6 to 3.9 g / cm 3 ; Plasticizer: 2-5 parts by weight Curing agent: 0.9~1.6 parts by weight, the curing agent is vinyltriamine; Accelerator: 2-3 parts by weight Additives: 8-12 parts by weight, the additives are non-tar pitch.

2. The protective coating for reusable templates according to claim 1, characterized in that: The rare earth oxide is Er2O3; or / and the dispersant is sodium polyacrylate; or / and the plasticizer is xylene phosphate; or / and the coagulant is calcium aluminate.

3. The protective coating for reusable templates according to claim 1, characterized in that: The average particle size of the nano-alumina is 60~70nm; or / and the epoxy resin density is 1.1-1.3g / cm³, and the viscosity is 7500~8000Pa•s.

4. A protective treatment method for reusable templates, characterized in that, Spray the protective coating according to any one of claims 1-3 onto the template surface.

5. The protective treatment method for reusable templates according to claim 4, characterized in that, The process includes the following: S1. After the concrete formwork is made, clean the surface of the formwork and apply a layer of water-based primer to the surface of the formwork. S2. Spray protective coating on the template surface.

6. The protective treatment method for reusable templates according to claim 5, characterized in that, In step S2, carboxymethyl cellulose is added as a viscosity modifier during the spraying of the protective coating, and the amount of carboxymethyl cellulose used is 2.5~3% of the total weight of the coating.

7. The protective treatment method for reusable templates according to claim 5, characterized in that, In step S2, the protective coating shall be sprayed no less than three times, with an interval of no less than 3 hours, and the thickness of each spray coating shall be no less than 0.03 mm.

8. The protective treatment method for reusable templates according to claim 5, characterized in that, In step S1, after the template is completed, the vertical strip edge on the inner side of the template is cut to form a wedge-shaped protrusion on the inner side, and then the template surface is cleaned.

9. The protective treatment method for reusable templates according to claim 5, characterized in that, In step S1, after applying a water-based primer to the template surface, the template surface is roughened, and then a protective coating is sprayed on.

10. The protective treatment method for reusable templates according to any one of claims 5-9, characterized in that, After step S2 is completed, continue to brush a lubricating isolation layer on the template surface: after the interface layer has formed a film, before pouring the wall, brush machine oil evenly on the interface layer on the inner surface of the template, and the machine oil completely covers the interface layer.

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