Plastering mortar for external thermal insulation of exterior wall and preparation method of plastering mortar

Abstract

The invention relates to the field of mortar production, and particularly discloses plastering mortar for external thermal insulation of an external wall and a preparation method of the plastering mortar. The invention discloses plastering mortar for external thermal insulation of an external wall. The plastering mortar is prepared from the following components in parts by weight: 50 to 66 parts of a cementing material, 40 to 80 parts of sand, 0.5 to 1.5 parts of fibers, 8 to 12 parts of latex powder, 0.2 to 0.5 part of hydroxypropyl methyl cellulose ether, 0.3 to 0.8 part of a water reducing agent, 0.01 to 0.05 part of an air entraining agent and 1 to 3 parts of a corrosion inhibitor, the corrosion inhibitor and the latex powder are compounded to form physical and chemical dual protection on the steel bars, so that the purpose that chloride ions in salt mist do not easily cause electrochemical corrosion of the steel bars, and the strength of the steel bars is reduced is achieved; the method has the advantage of being easy to operate.

Description

Technical Field

[0001] This application relates to the field of mortar production, and more specifically, to a plastering mortar for external wall insulation and its preparation method. Background Technology

[0002] Plastering mortar is a type of mortar applied to the surface of buildings or building components. Based on its function, plastering mortar can be classified into ordinary plastering mortar, decorative mortar, and plastering mortar with certain special functions. Plastering mortar requires good workability, easily applied as a uniform and smooth thin layer for convenient construction. It should also have high adhesion, ensuring the mortar layer bonds firmly to the substrate without cracking or peeling over time. In humid environments or areas susceptible to external forces, it should also possess high water resistance and strength.

[0003] In coastal areas, sea breezes carry salt spray that adheres to the surface of exterior walls and seeps into the walls through capillary action. Although the highly alkaline environment in concrete forms a passivation film on the surface of the reinforcing steel, chloride ions in the salt spray can penetrate this film, thereby triggering electrochemical corrosion of the reinforcing steel and causing a decrease in its strength. Summary of the Invention

[0004] In order to prevent chloride ions in salt spray from causing electrochemical corrosion of steel bars and thus reducing their strength, this application provides a plastering mortar for external wall insulation and its preparation method.

[0005] In the first aspect, this application provides a plastering mortar for external wall insulation, adopting the following technical solution:

[0006] An external wall insulation plastering mortar comprises the following components in parts by weight: 50-66 parts of cementitious material, 40-80 parts of sand, 0.5-1.5 parts of fiber, 8-12 parts of latex powder, 0.2-0.5 parts of hydroxypropyl methylcellulose ether, 0.3-0.8 parts of water-reducing agent, 0.01-0.05 parts of air-entraining agent, and 1-3 parts of rust inhibitor.

[0007] By adopting the above technical solutions, the rust inhibitor can directly inhibit the electrochemical corrosion of metals, especially in environments where chloride ions penetrate or where plastering mortar is prone to carbonization, thus delaying the cracking of the mortar layer caused by rust expansion. The film-forming properties of the latex powder can reduce the penetration of moisture and corrosive media, indirectly reducing the risk of metal corrosion. Together with the rust inhibitor, it forms a dual protection of "physical + chemical", thereby making it difficult for chloride ions in salt spray to cause electrochemical corrosion of steel bars, leading to a decrease in the strength of the steel bars.

[0008] Preferably, the cementitious material includes cement, mineral powder, fly ash and silica fume, and the mass ratio of cement, mineral powder, fly ash and silica fume is (50~65):15:(10~15):(3~8).

[0009] By adopting the above technical solutions, the addition of mineral powder and fly ash reduces the amount of cement used in the plastering mortar, reduces the heat of hydration and drying shrinkage generated during the construction of the plastering mortar, thereby reducing the risk of cracking of the plastering mortar. This makes it difficult for chloride ions in the salt spray to come into contact with the steel bars through the gaps in the plastering mortar. The filling effect of silica fume can reduce harmful pores and block the propagation path of shrinkage cracks, thereby further achieving the goal of making it difficult for chloride ions in the salt spray to cause electrochemical corrosion of the steel bars, leading to a decrease in the strength of the steel bars.

[0010] Preferably, the rust inhibitor comprises calcium nitrite.

[0011] By adopting the above technical solution, the NO2 released by calcium nitrite is reduced. - Ions and Fe on the surface of steel reinforcement 2+ The reaction generates a dense γ-Fe2O3 passivation film, which blocks the anodic reaction of electrochemical corrosion and maintains the protective effect even in the presence of chloride ions.

[0012] Preferably, the rust inhibitor comprises calcium nitrite and diethanolamine, and the mass ratio of calcium nitrite to diethanolamine is 1:(1~1.5).

[0013] By employing the above technical solution, the -OH and -NH groups in the diethanolamine molecule are adsorbed onto the metal surface, forming a hydrophobic protective layer that blocks H2O, O2, and Cl-. - Contact; the combination of diethanolamine and calcium nitrite makes NO2 - Passivating the anode and blocking the cathode with diethanolamine improves the rust-inhibiting effect. In addition, diethanolamine can maintain a high-alkaline environment, which protects the nitrite ions of calcium nitrite from decomposition, thereby maintaining the activity of calcium nitrite and improving the rust-inhibiting effect.

[0014] Preferably, the plastering mortar further includes 3 to 5 parts by weight of ceramic microspheres.

[0015] By adopting the above technical solutions, ceramic microspheres have a low density, and the addition of ceramic microspheres can reduce the bulk density of mortar, thereby reducing the overall load of the external wall insulation system and reducing the structural burden on the wall. In addition, the spherical structure of ceramic microspheres can evenly disperse the shrinkage stress of the plastering mortar, reduce the risk of drying cracking of the plastering mortar, and synergistically reinforce the plastering mortar with fibers. The closed-cell design of hollow microspheres can make hollow microspheres non-absorb water, reduce the migration and damage of water in freeze-thaw cycles, thereby reducing the quality loss of plastering mortar in freeze-thaw cycles.

[0016] Preferably, the plastering mortar further includes 1 to 2 parts by weight of zinc borate.

[0017] By adopting the above technical solution, the weak alkalinity of zinc borate can neutralize acidic substances and reduce the carbonation rate of plastering mortar.

[0018] Secondly, this application provides a method for preparing plastering mortar for external wall insulation, using the following technical solution:

[0019] A method for preparing plastering mortar for external wall insulation includes the following steps:

[0020] S1. The fiber is premixed with a small amount of sand to obtain the first mixture. The cementitious material is mixed evenly with the remaining sand, and then water-reducing agent, rust inhibitor, air-entraining agent, rubber powder and hydroxypropyl methylcellulose ether are added and mixed evenly to obtain the second mixture.

[0021] S2. Mix the latex powder, the first mixture, and the second mixture evenly to obtain the plastering mortar.

[0022] By adopting the above technical solution, the method of this application has the advantage of being simple to operate.

[0023] A method for preparing plastering mortar for external wall insulation includes the following steps:

[0024] S0. Add the rust inhibitor to water to obtain a rust inhibitor solution. Clean the ceramic microspheres with sodium hydroxide and dry them. Then, immerse the dried ceramic microspheres in the rust inhibitor solution and dry them to obtain pretreated ceramic microspheres.

[0025] S1. The fiber is premixed with a small amount of sand to obtain the first mixture. The cementitious material, pretreated ceramic microspheres and the remaining sand are mixed evenly. Then, rubber powder, water-reducing agent, air-entraining agent and hydroxypropyl methylcellulose ether are added and mixed evenly to obtain the second mixture.

[0026] S2. Mix the latex powder, the first mixture, and the second mixture evenly to obtain the plastering mortar.

[0027] In summary, this application has the following beneficial effects:

[0028] 1. Rust inhibitors can directly inhibit the electrochemical corrosion of metals, especially in environments where chloride ions penetrate or where plastering mortar is prone to carbonization, thus delaying the cracking of the mortar layer caused by rust expansion; the film-forming properties of latex powder can reduce the penetration of moisture and corrosive media, indirectly reducing the risk of metal corrosion, forming a "physical + chemical" dual protection with rust inhibitors, thereby achieving the purpose of making it difficult for chloride ions in salt spray to cause electrochemical corrosion of steel bars.

[0029] 2. The method of this application uniformly covers the air-entraining agent, rust inhibitor, and water-reducing agent on the surface of cementitious materials and sand by atomized spraying, thereby making it less likely that the water-reducing agent, air-entraining agent, and rust inhibitor will be in excessive or insufficient in certain areas. Detailed Implementation

[0030] The present application will be further described in detail below with reference to embodiments and comparative examples. The raw materials used in the preparation examples and embodiments of this application are all commercially available. Among them, the sand is 40-140 mesh, the cement is ordinary silicate cement purchased from Foshan Runhe Building Materials Co., Ltd., the mineral powder is purchased from Xinyang Pingqiao District Xinrun Building Materials Factory, item number 071, the fly ash is purchased from Lingshou County Qianfu Mineral Products Processing Plant, the silica fume is purchased from Lingshou County Dongyan Mineral Products Co., Ltd., the sand particle size is ≤1.18mm, and the proportion of 0.3-0.6mm particles is >45%, and the mud content is less than 3%, the fiber is polyvinyl alcohol fiber purchased from Taian Haili New Materials Co., Ltd., the fiber length is 6mm, the latex powder is redispersible latex powder VAE purchased from Shandong Jinrong Chemical Technology Co., Ltd., the hydroxypropyl methylcellulose ether is purchased from Jinan Ruilin Chemical Co., Ltd., the rosin resin air-entraining agent is purchased from Jiangsu Subote New Materials Co., Ltd. GYQ®-Ⅰ, the polycarboxylate water-reducing agent is purchased from Shandong Jinrong Chemical Technology Co., Ltd., the ceramic microspheres are purchased from Dalian Yibang Technology Co., Ltd., and the rubber powder is purchased from Lingshou County Shifeng Mining Processing Plant, specification 30 mesh.

[0031] Example of raw material preparation

[0032] Preparation Example 1

[0033] Take 50kg of cement, 15kg of mineral powder, 10kg of fly ash and 3kg of silica fume and mix them evenly to obtain a cementitious material.

[0034] Preparation Example 2

[0035] Take 65kg of cement, 15kg of mineral powder, 15kg of fly ash and 8kg of silica fume and mix them evenly to obtain a cementitious material.

[0036] Preparation Example 3

[0037] Take 58 kg of cement, 15 kg of mineral powder, 13 kg of fly ash and 5 kg of silica fume and mix them evenly to obtain a cementitious material.

[0038] Example

[0039] Example 1

[0040] A method for preparing plastering mortar for external wall insulation includes the following steps:

[0041] S0. Weigh out each component according to the mass percentage: 50 kg of cementitious material, 40 kg of sand, 0.5 kg of fiber, 8 kg of latex powder, 0.2 kg of hydroxypropyl methylcellulose ether, 0.3 kg of water-reducing agent, 0.01 kg of air-entraining agent, and 1 kg of rust inhibitor. The air-entraining agent is a rosin resin-based air-entraining agent, the water-reducing agent is a polycarboxylate-based water-reducing agent, and the rust inhibitor is calcium nitrite.

[0042] S1. The fiber is premixed with a small amount of sand to obtain the first mixture. The cementitious material is mixed evenly with the remaining sand, and then the rust inhibitor, water-reducing agent, air-entraining agent, rubber powder and cellulose ether are added and mixed evenly to obtain the second mixture.

[0043] S2. Mix the latex powder, the first mixture, and the second mixture evenly to obtain a plastering mortar, wherein the cementitious material is the cementitious material prepared in Preparation Example 1.

[0044] Example 2

[0045] The difference between this embodiment and Example 1 is as follows: S0, each component is weighed according to the mass parts: 66 kg of cementitious material, 80 kg of sand, 1.5 kg of fiber, 12 kg of latex powder, 0.5 kg of hydroxypropyl methylcellulose ether, 0.8 kg of water-reducing agent, 0.05 kg of air-entraining agent, and 3 kg of rust inhibitor. The air-entraining agent is a rosin resin-based air-entraining agent, the water-reducing agent is a polycarboxylate-based water-reducing agent, the rust inhibitor is calcium nitrite, and the cementitious material is the cementitious material prepared in Example 1.

[0046] Example 3

[0047] The difference between this embodiment and Example 1 is as follows: S0, each component is weighed according to the mass parts: 60 kg of cementitious material, 60 kg of sand, 1 kg of fiber, 10 kg of latex powder, 0.35 kg of hydroxypropyl methylcellulose ether, 0.5 kg of water-reducing agent, 0.03 kg of air-entraining agent, and 2 kg of rust inhibitor. The air-entraining agent is a rosin resin-based air-entraining agent, the water-reducing agent is a polycarboxylate-based water-reducing agent, the rust inhibitor is calcium nitrite, and the cementitious material is the cementitious material prepared in Example 1.

[0048] Example 4

[0049] The difference between this embodiment and Example 3 is that the gelling material used is the gelling material prepared in Example 2.

[0050] Example 5

[0051] The difference between this embodiment and Example 3 is that the gelling material used is the gelling material prepared in Example 3.

[0052] Example 6

[0053] The difference between this embodiment and Embodiment 5 is that the rust inhibitor uses calcium nitrite and diethanolamine, and the mass ratio of calcium nitrite to diethanolamine is 1:1.

[0054] Example 7

[0055] The difference between this embodiment and Embodiment 5 is that the rust inhibitor uses calcium nitrite and diethanolamine, and the mass ratio of calcium nitrite to diethanolamine is 1:1.5.

[0056] Example 8

[0057] The difference between this embodiment and Embodiment 5 is that the rust inhibitor uses calcium nitrite and diethanolamine, and the mass ratio of calcium nitrite to diethanolamine is 1:1.25.

[0058] Example 9

[0059] A method for preparing plastering mortar for external wall insulation includes the following steps:

[0060] S00. Weigh out each component according to the mass parts: 60 kg of cementitious material, 60 kg of sand, 1 kg of fiber, 10 kg of latex powder, 0.35 kg of hydroxypropyl methylcellulose ether, 0.5 kg of water-reducing agent, 0.03 kg of air-entraining agent, 2 kg of rust inhibitor, and 3 kg of ceramic microspheres. The air-entraining agent is a rosin resin-based air-entraining agent, the water-reducing agent is a polycarboxylate-based water-reducing agent, the cementitious material is the cementitious material prepared in Preparation Example 3, and the rust inhibitor is calcium nitrite and diethanolamine, with the mass ratio of calcium nitrite to diethanolamine being 1:1.25.

[0061] S0. Dissolve calcium nitrite in water at 40°C to obtain a rust inhibitor solution with a mass concentration of 40%. Soak ceramic microspheres in a sodium hydroxide aqueous solution with a mass concentration of 10% for 1 hour, then wash with deionized water until neutral, and then dry in an oven at 60°C. Soak the dried ceramic microspheres in the rust inhibitor solution and dry at 50°C to obtain pretreated ceramic microspheres.

[0062] S1. The fiber is premixed with a small amount of sand to obtain the first mixture. The cementitious material, pretreated ceramic microspheres and the remaining sand are mixed evenly. Then, water-reducing agent, diethanolamine, air-entraining agent, rubber powder and cellulose ether are added and mixed evenly to obtain the second mixture.

[0063] S2. Mix the latex powder, the first mixture, and the second mixture evenly to obtain the plastering mortar.

[0064] Example 10

[0065] The difference between this embodiment and Example 9 is as follows: S00, each component is weighed according to the mass parts: 60 kg of cementitious material, 60 kg of sand, 1 kg of fiber, 10 kg of latex powder, 0.35 kg of hydroxypropyl methylcellulose ether, 0.5 kg of water-reducing agent, 0.03 kg of air-entraining agent, 2 kg of rust inhibitor, and 5 kg of ceramic microspheres. The air-entraining agent is a rosin resin-based air-entraining agent, the water-reducing agent is a polycarboxylic acid-based water-reducing agent, the cementitious material is the cementitious material prepared in Preparation Example 3, and the rust inhibitor is calcium nitrite and diethanolamine, with the mass ratio of calcium nitrite to diethanolamine being 1:1.25.

[0066] Example 11

[0067] The difference between this embodiment and Example 9 is as follows: S00, each component is weighed according to the mass parts: 60 kg of cementitious material, 60 kg of sand, 1 kg of fiber, 10 kg of latex powder, 0.35 kg of hydroxypropyl methylcellulose ether, 0.5 kg of water-reducing agent, 0.03 kg of air-entraining agent, 2 kg of rust inhibitor, and 4 kg of ceramic microspheres. The air-entraining agent is a rosin resin-based air-entraining agent, the water-reducing agent is a polycarboxylic acid-based water-reducing agent, the cementitious material is the cementitious material prepared in Preparation Example 3, and the rust inhibitor is calcium nitrite and diethanolamine, with the mass ratio of calcium nitrite to diethanolamine being 1:1.25.

[0068] Example 12

[0069] A method for preparing plastering mortar for external wall insulation includes the following steps:

[0070] S0. Weigh out each component according to the mass percentage: 60 kg of cementitious material, 60 kg of sand, 1 kg of fiber, 10 kg of latex powder, 0.35 kg of hydroxypropyl methylcellulose ether, 0.5 kg of water-reducing agent, 0.03 kg of air-entraining agent, 4 kg of ceramic microspheres, and 2 kg of rust inhibitor. The air-entraining agent is a rosin resin-based air-entraining agent, the water-reducing agent is a polycarboxylate-based water-reducing agent, the cementitious material is the cementitious material prepared in Preparation Example 3, and the rust inhibitor is calcium nitrite and diethanolamine, with the mass ratio of calcium nitrite to diethanolamine being 1:1.25.

[0071] S1. The fiber is premixed with a small amount of sand to obtain the first mixture. The cementitious material is mixed evenly with the remaining sand, and then water-reducing agent, air-entraining agent, rust inhibitor, rubber powder, ceramic microspheres and cellulose ether are added and mixed evenly to obtain the second mixture.

[0072] S2. Mix the latex powder, the first mixture, and the second mixture evenly to obtain the plastering mortar.

[0073] Example 13

[0074] A method for preparing plastering mortar for external wall insulation includes the following steps:

[0075] S00. Weigh out each component according to the following mass percentages: 60 kg of cementitious material, 60 kg of sand, 1 kg of fiber, 10 kg of latex powder, 0.35 kg of hydroxypropyl methylcellulose ether, 0.5 kg of water-reducing agent, 0.03 kg of air-entraining agent, 4 kg of ceramic microspheres, 1 kg of zinc borate, and 2 kg of rust inhibitor. The air-entraining agent is a rosin resin-based air-entraining agent, the water-reducing agent is a polycarboxylate-based water-reducing agent, the cementitious material is the cementitious material prepared in Preparation Example 3, and the rust inhibitor is calcium nitrite and diethanolamine, with a mass ratio of calcium nitrite to diethanolamine of 1:1.25.

[0076] S0. Dissolve calcium nitrite in water at 40°C to obtain a rust inhibitor solution with a mass concentration of 40%. Soak ceramic microspheres in a 10% sodium hydroxide aqueous solution for 1 hour, then wash with deionized water until neutral, and then dry in an oven at 60°C. Immerse the dried ceramic microspheres in the rust inhibitor solution and dry at 50°C to obtain pretreated ceramic microspheres. Mix zinc borate with the pretreated ceramic microspheres evenly to obtain a mixture.

[0077] S1. The fiber is premixed with a small amount of sand to obtain the first mixture. The cementitious material, the mixture and the remaining sand are mixed evenly. Then, the water-reducing agent, the air-entraining agent, the diethanolamine and the cellulose ether are added and mixed evenly to obtain the second mixture.

[0078] S2. Mix the latex powder, the first mixture, and the second mixture evenly to obtain the plastering mortar.

[0079] Example 14

[0080] The difference between this embodiment and Embodiment 13 is that 2 kg of zinc borate was used.

[0081] Example 15

[0082] The difference between this embodiment and Embodiment 13 is that: 1.5 kg of zinc borate.

[0083] Example 16

[0084] A method for preparing plastering mortar for external wall insulation includes the following steps:

[0085] S0. Weigh out each component according to the mass percentage: 60 kg of cementitious material, 60 kg of sand, 1 kg of fiber, 10 kg of latex powder, 0.35 kg of hydroxypropyl methylcellulose ether, 0.5 kg of water-reducing agent, 0.03 kg of air-entraining agent, 4 kg of ceramic microspheres, 1 kg of zinc borate, and 2 kg of rust inhibitor. The air-entraining agent is a rosin resin-based air-entraining agent, the water-reducing agent is a polycarboxylate-based water-reducing agent, the cementitious material is the cementitious material prepared in Preparation Example 3, and the rust inhibitor is calcium nitrite and diethanolamine, with the mass ratio of calcium nitrite to diethanolamine being 1:1.25.

[0086] S1. The fiber is premixed with a small amount of sand to obtain the first mixture. The cementitious material is mixed evenly with the remaining sand, and then water-reducing agent, air-entraining agent, zinc borate, rust inhibitor, rubber powder, ceramic microspheres and cellulose ether are added and mixed evenly to obtain the second mixture.

[0087] S2. Mix the latex powder, the first mixture, and the second mixture evenly to obtain the plastering mortar.

[0088] Comparative Example

[0089] Comparative Example 1

[0090] A method for preparing plastering mortar for external wall insulation includes the following steps:

[0091] S0. Weigh each component according to the mass percentage: 50 kg of cementitious material, 40 kg of sand, 0.5 kg of fiber, 0.2 kg of hydroxypropyl methylcellulose ether, 0.3 kg of water-reducing agent, 0.01 kg of air-entraining agent, and 1 kg of rust inhibitor. The air-entraining agent is a rosin resin-based air-entraining agent, the water-reducing agent is a polycarboxylate-based water-reducing agent, and the rust inhibitor is calcium nitrite.

[0092] S1. The fiber is premixed with a small amount of sand to obtain the first mixture. The cementitious material is mixed evenly with the remaining sand, and then water-reducing agent, air-entraining agent, rust inhibitor, rubber powder and cellulose ether are added and mixed evenly to obtain the second mixture.

[0093] S2. Mix the first mixture and the second mixture evenly to obtain the plastering mortar.

[0094] Comparative Example 2

[0095] A method for preparing plastering mortar for external wall insulation includes the following steps:

[0096] S0. Weigh each component according to the mass percentage: 50 kg of cementitious material, 40 kg of sand, 0.5 kg of fiber, 8 kg of latex powder, 0.2 kg of hydroxypropyl methylcellulose ether, 0.3 kg of water-reducing agent, and 0.01 kg of air-entraining agent. The air-entraining agent is a rosin resin-based air-entraining agent, and the water-reducing agent is a polycarboxylate-based water-reducing agent.

[0097] S1. The fiber is premixed with a small amount of sand to obtain the first mixture. The cementitious material is mixed evenly with the remaining sand, and then water-reducing agent, air-entraining agent, rust inhibitor, rubber powder and cellulose ether are added and mixed evenly to obtain the second mixture.

[0098] S2. Mix the latex powder, the first mixture, and the second mixture evenly to obtain the plastering mortar.

[0099] Performance testing

[0100] Detection methods

[0101] The neutral salt spray resistance of Examples 1 to 16 and Comparative Examples 1 to 2 was tested according to GB / T 1771-2007 (1000h), and the test results are recorded in Table 1.

[0102] According to JG / T 149-2018, the freeze-thaw resistance of Examples 1 to 16 and Comparative Examples 1 to 2 was tested, and the test results are recorded in Table 1. When preparing the specimens for the above test items, the mass ratio of plastering mortar to water was 2:1.

[0103] Table 1

[0104] As can be seen from Example 1 and Comparative Example 1, and Table 1, the addition of rust inhibitor can significantly improve the salt spray resistance of plastering mortar.

[0105] As can be seen from Example 1 and Comparative Example 2, and Table 1, the addition of latex powder can significantly improve the salt spray resistance and freeze-thaw cycle performance of the plastering mortar. The reason is that the latex powder forms a continuous polymer film after the mortar hardens, which fills the capillary pores, reduces the chloride ion diffusion coefficient, and thus improves the corrosion resistance of the plastering mortar.

[0106] Combining Examples 11 and 12 with Table 1, it can be seen that the performance of the plastering mortar using ceramic microspheres loaded with calcium nitrite in Example 11 is higher than that of the plastering mortar using a direct mixture of ceramic microspheres and calcium nitrite in Example 12. This is because: the ceramic microspheres loaded with calcium nitrite can slow down the release of calcium nitrite, causing it to be lost in the early stages of plastering mortar application. Simultaneously, the alumina in the ceramic microspheres can react synergistically with calcium nitrite to generate alkaline substances, thus stabilizing the alkaline environment of the plastering mortar and reducing the corrosion of the plastering mortar by acidic substances in the air. Furthermore, when fly ash consumes calcium hydroxide, the alkali reserve in the mortar decreases, making it easier for carbon dioxide to penetrate and react with calcium hydroxide to form calcium carbonate, increasing the risk of damage to the passivation film on the reinforcing steel. However, when the pH decreases due to carbonization, the silicate layer on the surface of the ceramic microspheres loaded with rust inhibitor dissolves, accelerating the release of the rust inhibitor and making the reinforcing steel less susceptible to corrosion.

[0107] As can be seen from Examples 11 and 13 and Table 1, the addition of zinc borate can significantly improve the performance of plastering mortar. This is because zinc borate can hydrolyze to generate borate and zinc ions, forming a dense complex film on the surface of the reinforcing steel, which inhibits the cathodic oxygen reduction reaction. In addition, the surface of ceramic microspheres can adsorb borate, making it less likely for borate to react with the components in cement and cause failure. Furthermore, the addition of zinc borate can act as a pH buffer, making it less likely for the slowly released calcium nitrite in the ceramic microspheres to decompose due to pH changes, thereby further improving the corrosion resistance of the plastering mortar.

[0108] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A plastering mortar for external wall insulation, characterized in that, It comprises the following components in parts by weight: 50-66 parts of cementitious material, 40-80 parts of sand, 0.5-1.5 parts of fiber, 8-12 parts of latex powder, 0.2-0.5 parts of hydroxypropyl methylcellulose ether, 0.3-0.8 parts of water-reducing agent, 0.01-0.05 parts of air-entraining agent, and 1-3 parts of rust inhibitor.

2. The plastering mortar for external wall insulation according to claim 1, characterized in that, The cementitious material includes cement, mineral powder, fly ash and silica fume, and the mass ratio of cement, mineral powder, fly ash and silica fume is (50~65):15:(10~15):(3~8).

3. The plastering mortar for external wall insulation according to claim 1, characterized in that, The rust inhibitor includes calcium nitrite.

4. The plastering mortar for external wall insulation according to claim 1, characterized in that, The rust inhibitor comprises calcium nitrite and diethanolamine, and the mass ratio of calcium nitrite to diethanolamine is 1:(1~1.5).

5. The plastering mortar for external wall insulation according to claim 1, characterized in that, The plastering mortar also includes 3 to 5 parts by weight of ceramic microspheres.

6. The plastering mortar for external wall insulation according to claim 1, characterized in that, The finishing mortar also includes 1 to 2 parts by weight of zinc borate.

7. A method for preparing a plastering mortar for external wall insulation, characterized in that, Includes the following steps: S1. The fiber is premixed with a small amount of sand to obtain the first mixture. The cementitious material is mixed evenly with the remaining sand, and then water-reducing agent, rust inhibitor, air-entraining agent, rubber powder and hydroxypropyl methylcellulose ether are added and mixed evenly to obtain the second mixture. S2. Mix the latex powder, the first mixture, and the second mixture evenly to obtain the plastering mortar.

8. A method for preparing a plastering mortar for external wall insulation, characterized in that, Includes the following steps: S0. Add the rust inhibitor to water to obtain a rust inhibitor solution. Clean the ceramic microspheres with sodium hydroxide and dry them. Then, immerse the dried ceramic microspheres in the rust inhibitor solution and dry them to obtain pretreated ceramic microspheres. S1. The fiber is premixed with a small amount of sand to obtain the first mixture. The cementitious material, pretreated ceramic microspheres and the remaining sand are mixed evenly. Then, rubber powder, water-reducing agent, air-entraining agent and hydroxypropyl methylcellulose ether are added and mixed evenly to obtain the second mixture. S2. Mix the latex powder, the first mixture, and the second mixture evenly to obtain the plastering mortar.

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