Moisture-proof, mildew-proof and impermeable mortar for inhibiting alkali efflorescence of base layer and construction method

Abstract

The invention provides moisture-proof, mildew-proof and impermeable mortar for inhibiting alkali efflorescence of a base layer and a construction method, and belongs to the technical field of building materials. The moisture-proof, mildew-proof and impermeable mortar for inhibiting alkali efflorescence of the base layer comprises the following raw materials in parts by weight: ordinary mortar raw materials and 30-60 parts of metakaolin, and the total amount is 1000 parts, and 0.9-3 parts of potassium hydrogen phosphate.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and particularly relates to a moisture-proof, mildew-proof and seepage-proof mortar for inhibiting alkali return of a base layer and a construction method. Background Art

[0002] In indoor building scenarios, wall alkali reversion, peeling and mold are common problems. These problems occur frequently in areas with high humidity all year round or in buildings with insufficient waterproofing construction. Studies show that about 50% of households are troubled by wall peeling and mold growth, and the long-term dampness of the wall is one of the key factors causing such problems. At the same time, studies have shown that more than 30% of buildings face varying degrees of wall alkali reversion and mold. The harm caused by wall alkali reversion should not be underestimated. Alkali reversion will produce white crystals, black spots or stains on the wall, which greatly destroys the beauty of the wall and makes the home environment look shabby, messy and untidy. Moreover, long-term alkali reversion problems will cause the putty layer, latex paint layer, etc. on the wall surface to gradually fall off. After losing these protective barriers, moisture and air can easily penetrate into the wall, thereby accelerating the aging and corrosion process of the wall material, resulting in a decrease in the structural strength of the wall, and ultimately affecting the service life of the house. In addition, the alkaline substances on the surface of the wall after alkali return and the microorganisms such as mold that grow on it will release harmful gases and spores into the air. After inhalation by the human body, it is easy to cause respiratory diseases, allergies and other symptoms, which will damage health. Summary of the invention

[0003] In view of the above technical problems, the present invention provides a moisture-proof, mildew-proof and anti-seepage mortar and a construction method for inhibiting alkali return of the base layer, in order to at least partially solve the above technical problems. The specific technical solutions provided by the present invention are as follows.

[0004] As a first aspect of the present invention, a moisture-proof, mildew-proof and anti-seepage mortar for inhibiting alkali return of a base layer is provided. Its constituent raw materials include, by weight: ordinary mortar raw materials, and 30-60 parts of kaolin, with a total amount of 1000 parts; and 0.9-3 parts of potassium hydrogen phosphate.

[0005] As a second aspect of the present invention, a construction method of the above-mentioned moisture-proof, mildew-proof and anti-seepage mortar for inhibiting alkali return of the base layer is provided, comprising: adding water to the moisture-proof, mildew-proof and anti-seepage mortar for inhibiting alkali return of the base layer and stirring evenly, and then coating it on the surface of the base layer.

[0006] In an embodiment of the present invention, a moisture-proof, mildew-proof and anti-seepage mortar (hereinafter referred to as mortar) and a construction method for inhibiting alkali return of a base layer are provided. The hydration products of the mortar are regulated by adding potassium hydrogen phosphate. In the early hydration process, potassium hydrogen phosphate stimulates the hydration of metakaolin to generate calcium aluminum double hydroxides (LDHs) and aluminum hydroxide (AH3 ) gel; in the later hydration process, the metakaolin, limestone powder and calcium hydroxide react with carbon aluminate to form hydrated calcium carbon aluminate and hydrated calcium aluminosilicate (CASH) gel. Calcium aluminum double hydroxide (LDHs), aluminum hydroxide (AH 3 ) gel, hydrated calcium carbon aluminate and hydrated calcium aluminosilicate (CASH) gel interweave to form a dense microstructure, which significantly improves the anti-seepage ability of the mortar. Secondly, the special arrangement of layered double hydroxide (LDHs) crystals in the mortar overlaps and is parallel, which hinders the passage of water molecules. The AH in the pores 3 Gel and CASH gel have strong hydrogen bond adsorption on water molecules, further hindering the diffusion of water molecules, thereby significantly improving the moisture-proof performance of the mortar. Then, the layers in the layered LDHs crystals are combined through weak van der Waals forces and electrostatic attraction. Alkaline substances can enter the interlayers of LDHs with water molecules, and form hydrogen bonds and hydration with the cations and oxygen atoms between the layers, and then be fixed in the interlayers, achieving the effect of inhibiting the return of alkali to the base layer. Finally, through the thin layer of mortar, moisture and seepage resistance can be achieved, the wall surface can be kept dry for a long time, the return of alkali to the base layer can be inhibited, and the wall structure can be kept safe for a long time, and the environment for the breeding of mold can be eradicated, thereby preventing the wall from getting moldy, protecting the wall coating from lasting like new, and keeping the indoor walls and spaces healthy. DETAILED DESCRIPTION

[0007] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0008] The formation process of wall alkali mold can be divided into four stages.

[0009] First of all, the base material of the building wall is usually concrete, cement products or cement mortar. Cement will produce alkaline substances such as calcium hydroxide when it is hydrated. This chemical reaction is inevitable and will continue slowly for a long time after the wall solidifies, causing alkaline substances in the wall, especially calcium hydroxide, to accumulate continuously.

[0010] Secondly, changes in the external environment are the key cause. Changes in air humidity, cracks and leaks in bathrooms and exterior walls can all cause the wall to become damp. Once the wall becomes damp, moisture will migrate through the wall. It will diffuse from areas with high humidity to areas with low humidity along the pores and cracks in the wall. In this process, moisture will move alkaline substances such as calcium hydroxide in the wall.

[0011] Then, when the water containing calcium hydroxide migrates to the wall surface, the water will slowly evaporate. As the water continues to evaporate, the concentration of calcium hydroxide on the wall surface becomes higher and higher. When it reaches a supersaturated state, calcium hydroxide will crystallize out of the solution to form a white substance. This is the alkali backflow phenomenon we see.

[0012] Finally, at the beginning of the alkali return, white powder or flocculent substances will appear on the surface of the wall, which is caused by the crystallization of calcium hydroxide. At this time, the appearance of the wall will be affected, but the effect on the structural performance of the wall will be small. As the alkali return continues, the precipitated calcium hydroxide will react with carbon dioxide in the air to form calcium carbonate. Since the volume of calcium carbonate is larger than that of calcium hydroxide, it will produce expansion stress on the surface of the wall, resulting in reduced adhesion between the putty layer, paint layer, etc. on the surface of the wall and the wall base, resulting in peeling and hollowing of the coating. The peeling and hollowing caused by the alkali return on the wall surface will further reduce the waterproof performance of the wall, allowing more moisture and air to enter the interior of the wall, aggravating the alkali return. At the same time, the alkaline environment created by alkaline substances such as calcium hydroxide provides suitable conditions for the growth of mold. When mold multiplies on the surface of the wall in large numbers, mold will appear, and black, green and other spots will appear on the surface of the wall, which will not only destroy the beauty of the wall, but also endanger human health.

[0013] In summary, it is of vital importance to develop new anti-alkali, moisture-proof, anti-seepage and anti-mildew materials suitable for indoor spaces of buildings. Such materials can effectively inhibit base layer leakage and alkali return, create a long-term healthy wall and space environment, and help realize a better living environment. From a market perspective, there is a huge demand for such materials, and the market prospects are very broad.

[0014] Based on this, the present invention provides a moisture-proof, mildew-proof and anti-seepage mortar and a construction method for inhibiting the return of alkali to the base layer. Among them, the components of the moisture-proof, mildew-proof and anti-seepage mortar include: ordinary mortar raw materials, as well as metakaolin and potassium hydrogen phosphate. The moisture-proof, mildew-proof and anti-seepage mortar for inhibiting the return of alkali to the base layer provided by the present invention can significantly improve the moisture-proof and anti-seepage ability of the thin layer back-water surface mortar, and at the same time has the effect of inhibiting the return of alkali to the base layer from damaging the wall surface, thereby preventing the wall surface from getting moldy.

[0015] As a first aspect of the present invention, a moisture-proof, mildew-proof and anti-seepage mortar for inhibiting alkali return of a base layer is provided. Its constituent raw materials include, by weight: ordinary mortar raw materials, and 30-60 parts of kaolin, with a total amount of 1000 parts; and 0.9-3 parts of potassium hydrogen phosphate.

[0016] In the embodiment of the present invention, potassium hydrogen phosphate is added to regulate the hydration products of the mortar. In the early hydration process, potassium hydrogen phosphate stimulates the hydration of metakaolin to generate calcium aluminum double hydroxides (LDHs) and aluminum hydroxide (AH 3) gel; in the later hydration process, kaolin, limestone and calcium hydroxide react with carbon aluminate to produce hydrated calcium carbon aluminate and hydrated calcium aluminosilicate (CASH) gel. Calcium aluminum double hydroxide (LDHs), aluminum hydroxide (AH 3 ) gel, hydrated calcium carbon aluminate and hydrated calcium aluminosilicate (CASH) gel interweave to form a dense microstructure, which significantly improves the anti-seepage ability of the mortar. Secondly, the special arrangement of layered double hydroxide (LDHs) crystals in the mortar overlaps and is parallel, which hinders the passage of water molecules. The AH in the pores 3 Gel and CASH gel have strong hydrogen bond adsorption on water molecules, further hindering the diffusion of water molecules, thereby significantly improving the moisture-proof performance of the mortar. Then, the layers in the layered LDHs crystals are combined through weak van der Waals forces and electrostatic attraction. Alkaline substances can enter the interlayers of LDHs with water molecules, and form hydrogen bonds and hydration with the cations and oxygen atoms between the layers, and then be fixed in the interlayers, achieving the effect of inhibiting the return of alkali to the base layer. Finally, through the thin layer of mortar, moisture and seepage resistance can be achieved, the wall surface can be kept dry for a long time, the return of alkali to the base layer can be inhibited, and the wall structure can be kept safe for a long time, and the environment for the breeding of mold can be eradicated, thereby preventing the wall from getting moldy, protecting the wall coating from lasting like new, and keeping the indoor walls and spaces healthy.

[0017] According to an embodiment of the present invention, the common mortar raw materials include: 400-600 parts of medium sand, 295-450 parts of ordinary Portland cement, 15-30 parts of limestone powder, and 30-60 parts of redispersible latex powder. The medium sand includes at least one of natural sand and artificial sand. The ordinary Portland cement includes at least one of gray cement and white cement. The particle size of the metakaolin is 1200-4000 mesh.

[0018] According to an embodiment of the present invention, the raw materials of the moisture-proof, mildew-proof and anti-seepage mortar further include: 8-12 parts of water reducer, 1.1-3.2 parts of additives. Potassium hydrogen phosphate includes at least one of dipotassium hydrogen phosphate and potassium dihydrogen phosphate. The additives include: 0.5-2 parts of cellulose ether, 0.4-0.8 parts of water repellent, and 0.2-0.4 parts of defoaming agent.

[0019] In an embodiment of the present invention, medium sand is matched with ordinary Portland cement and limestone powder to build a stable basic structure, giving the mortar good strength and rigidity. Redispersible latex powder increases the flexibility and adhesion of the mortar, making the application construction smoother and more firmly attached to the base. The water reducer reduces the water consumption while ensuring the strength, improves the fluidity, and facilitates the construction operation. The hydrophobic agent can effectively prevent moisture from invading, improve the moisture and impermeability of the mortar, and can effectively cope with humid environments. Cellulose ether retains moisture, allows cement to be fully hydrated, and enhances chemical stability. The defoamer eliminates bubbles inside the mortar, making the structure more uniform and dense, and further improving stability. These combined effectively inhibit base leakage and alkali return, making the wall surface less prone to mold, maintaining beauty, and ensuring the health of the indoor space. Among them, the redispersible latex powder can be selected from acrylate redispersible latex powder, vinyl acetate redispersible latex powder, etc.; the water reducer can be selected from lignin sulfonate water reducer, naphthalene water reducer, polycarboxylic acid water reducer, etc.; the cellulose ether can be selected from methyl cellulose ether, hydroxypropyl methyl cellulose ether, etc.; the hydrophobic agent can be selected from silicone hydrophobic agent, fatty acid hydrophobic agent, etc.; the defoamer can be selected from silicone defoamer, polyether defoamer, mineral oil defoamer, etc. It should be understood that in addition to the various types of redispersible latex powder, water reducer, cellulose ether, hydrophobic agent and defoamer mentioned above, in practical applications, other commonly used similar materials are also applicable, and the present invention is not limited thereto.

[0020] As a second aspect of the present invention, a construction method of the above-mentioned moisture-proof, mildew-proof and anti-seepage mortar for inhibiting alkali return of the base layer is provided, comprising: adding water to the moisture-proof, mildew-proof and anti-seepage mortar for inhibiting alkali return of the base layer and stirring it evenly, and then coating it on the surface of the base layer.

[0021] In an embodiment of the present invention, water is added to the anti-seepage mortar and stirred evenly, so that the various components of the mortar are fully integrated. When applied to the surface of the base layer, it can be closely attached, greatly enhancing the bonding force with the base layer, reducing the risk of hollowing and falling off, ensuring the long-term stability of the wall surface, and reducing the later maintenance cost. The complete protective layer formed by uniform coating can give full play to the anti-seepage and moisture-proof properties, and effectively prevent moisture from penetrating into the base layer. The mortar is in full contact with the base layer, and the special internal components can better fix the alkaline substances and inhibit the alkali return of the base layer. Avoid the alkali return phenomenon such as white crystals and black spots on the wall surface, maintain the beauty of the wall surface, and extend the service life of the wall surface. By waterproofing and moisture-proofing and inhibiting the return of alkali, the wall surface is kept dry, mold growth is eliminated from the root, the harm of mold to human health is reduced, and a healthy and comfortable living or working environment is created indoors. The construction method provided by the present invention is simple to operate, does not require special construction skills and complex equipment, can reduce construction preparation time and labor costs, allows construction personnel to quickly start work, speed up construction progress, and is particularly suitable for projects with tight construction periods.

[0022] According to the embodiment of the present invention, the mortar includes 1000 parts by weight and the water includes 220-250 parts by weight, so as to ensure that the workability and fluidity of the mortar are in the best state, so that the various components react fully, give full play to the performance of moisture-proof, mildew-proof, impermeability and inhibition of base alkali return, and ensure stable and reliable engineering quality. The base includes a concrete base or a cement mortar base to meet the needs of different construction projects.

[0023] Specifically, in some embodiments of the present invention, the construction method of the above-mentioned moisture-proof, mildew-proof and anti-seepage mortar for inhibiting alkali return of the base layer includes: weighing each component raw material according to the measurement, mixing evenly to obtain a moisture-proof, mildew-proof and anti-seepage mortar for inhibiting alkali return of the base layer; adding 220-250 parts of water to 1000 parts of anti-seepage mortar, mixing and stirring for 3 minutes, the stirring rate is 400-800r / min, standing for 2 minutes and stirring again for 1 minute to complete the mortar mixing; on the cleaned and solid concrete or cement mortar base, brush or roll the mortar twice, the thickness of a single brushing is not less than 1mm, and the thickness of two brushings is not less than 2mm, and the construction is completed after curing.

[0024] The present invention is further described below by examples and related test experiments. In the detailed description below, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present invention. However, it is obvious that one or more embodiments may also be implemented without these specific details. And, in the absence of conflict, the details in the following embodiments may be combined into other feasible embodiments at will. All instruments, consumables and reagents in the following examples, if not otherwise specified, may be obtained from commercial sources.

[0025] The raw material types and manufacturers used in the examples and comparative examples of the present invention are as follows.

[0026] Natural sand was purchased from Hebei Feixi New Material Technology Co., Ltd., river sand, mesh size 40-140 mesh;

[0027] Artificial sand was purchased from Liaoning Jinlun Mineral Products Co., Ltd., dolomite machine-made sand, mesh size 40-140 mesh;

[0028] Grey cement was purchased from Anhui Conch Cement Co., Ltd., model PO 42.5;

[0029] White cement was purchased from Aalborg Portland (Anqing) Co., Ltd., model PW 52.5;

[0030] Limestone powder was purchased from Jiangxi Guangyuan Chemical Co., Ltd., with a fineness of 800 mesh;

[0031] Metakaolin was purchased from Inner Mongolia Chaopai Building Materials Co., Ltd. with fineness of 1200 mesh and 4000 mesh;

[0032] The redispersible latex powder was purchased from Wacker Chemical (China) Co., Ltd., model 5044N;

[0033] Potassium hydrogen phosphate was purchased from Beijing Kangpu Huiwei Technology Co., Ltd., industrial grade;

[0034] Cellulose ether was purchased from Dow Chemical Company, USA, hydroxyethyl methyl cellulose, model WALOCEL TM MKW20000PP30;

[0035] The water reducer was purchased from Sika (China) Co., Ltd., model 530P;

[0036] The water repellent was purchased from Akzo Nobel Paints (China) Co., Ltd., model SEAL80;

[0037] The defoamer was purchased from Germany's Mingling Chemical, a silicone powder defoamer, model AGITANR P803.

[0038] Example 1

[0039] The raw materials and proportions of the moisture-proof, mildew-proof and anti-seepage mortar provided in Example 1 for inhibiting alkali return to the base layer are detailed in Table 1.

[0040] The construction method of the moisture-proof, mildew-proof and anti-seepage mortar specifically comprises the following steps.

[0041] (1) Weigh each raw material component according to the measurement, mix them evenly to obtain moisture-proof, mildew-proof and anti-seepage mortar.

[0042] (2) Add 250 parts of water to 1000 parts of mortar, mix and stir for 3 minutes at a stirring rate of 400 r / min. After standing for 2 minutes, stir again for 1 minute to complete the mortar mixing.

[0043] (3) Apply mortar twice on the cleaned and solid concrete base. The thickness of a single coat should not be less than 1 mm, and the thickness of two coats should not be less than 2 mm. After curing, the construction is completed.

[0044] The anti-seepage pressure of the mortar on the back water surface was tested according to JC / T 984-2011 "Polymer Cement Waterproof Mortar", and the tensile bond strength and lateral deformation were tested according to JC / T2090-2011 "Polymer Cement Waterproof Mortar". High permeability concrete hollow blocks were used. After sealing the bottom, the anti-seepage mortar was applied twice on the outer surface of the blocks. After curing, the blocks were filled with water, and sufficient calcium hydroxide was added to form a saturated calcium hydroxide solution. A back water surface moisture content and alkali return verification model was made, and the coating surface moisture content and alkali return damage were observed for a long time. The test results are shown in Table 1.

[0045] Example 2

[0046] For the raw materials and their proportions of the moisture-proof, mildew-proof and anti-seepage mortar for suppressing the return of alkalinity from the base layer provided in Example 2, please refer to Table 1. The construction method and the detection method are the same as those in Example 1, and the detection results are shown in Table 1.

[0047] Example 3

[0048] For the raw materials and their proportions of the moisture-proof, mildew-proof and anti-seepage mortar for suppressing the return of alkalinity from the base layer provided in Example 3, please refer to Table 1. The construction method and the detection method are the same as those in Example 1, and the detection results are shown in Table 1.

[0049] Example 4

[0050] For the raw materials and their proportions of the moisture-proof, mildew-proof and anti-seepage mortar for suppressing the return of alkalinity from the base layer provided in Example 4, please refer to Table 1.

[0051] The construction method of this moisture-proof, mildew-proof and anti-seepage mortar specifically includes the following steps.

[0052] (1) Weigh each raw material component according to the measurement, and mix them evenly to obtain the moisture-proof, mildew-proof and anti-seepage mortar.

[0053] (2) Add 220 parts of water to 1000 parts of the mortar, mix and stir for 3 min at a stirring rate of 800 r / min, let it stand still for 2 min and then stir for 1 min again to complete the stirring of the mortar.

[0054] (3) On the cleaned and solid concrete base layer, brush the mortar twice, with the thickness of each single brush coating not less than 1 mm and the thickness of the two brush coatings not less than 2 mm, and complete the construction after curing.

[0055] The detection method is the same as that in Example 1, and the detection results are shown in Table 1.

[0056] Comparative Example 1

[0057] For the raw materials and their proportions of the moisture-proof, mildew-proof and anti-seepage mortar for suppressing the return of alkalinity from the base layer provided in this Comparative Example 1, please refer to Table 1. The construction method and the detection method are the same as those in Example 1, and the detection results are shown in Table 1.

[0058] Comparative Example 2

[0059] For the raw materials and their proportions of the moisture-proof, mildew-proof and anti-seepage mortar for suppressing the return of alkalinity from the base layer provided in this Comparative Example 2, please refer to Table 1. The construction method and the detection method are the same as those in Example 1, and the detection results are shown in Table 1.

[0060] Comparative Example 3

[0061] This Comparative Example 3 is a commercially available moisture-proof and alkali-resistant polymer cement waterproof slurry, and the detection method is the same as that in Example 1, and the detection results are shown in Table 1.

[0062] Table 1 Mortar Mix Proportions and Detection Results of Examples 1 - 4 and Comparative Examples 1 - 3

[0063]

[0064] As shown in Table 1, the above embodiments and comparative examples and test data show that the moisture-proof, mildew-proof and anti-seepage mortar for inhibiting alkali return of the base provided by the present invention can regulate the hydration products of the mortar, namely, calcium aluminum double hydroxide (LDHs), aluminum hydroxide (AH 3 ) gel, hydrated calcium carbon aluminate and hydrated calcium aluminosilicate (CASH) gel to achieve moisture-proof, mildew-proof and anti-seepage effects. Among them, calcium aluminum double hydroxide forms a dense and specially arranged nanostructure in the mortar layer, AH 3 The adsorption of water molecules by gel and CASH gel, and the solidification of alkaline substances by LDHs, can resist the maximum 1.5MPa water pressure penetration when coated with a thin layer of 2mm, and the surface moisture content of the coating can be 0 after 28 days, achieving moisture-proof, mildew-proof, anti-seepage and inhibition of base alkali return of thin-layer mortar, with significantly better effects than existing technologies. The specific comparative analysis is as follows.

[0065] Examples 1 to 3 are solutions with different amounts of potassium hydrogen phosphate and metakaolin. It can be seen that with the increase in the amount of potassium hydrogen phosphate and metakaolin, the water resistance of the mortar on the back surface gradually increases, and the moisture content of the coating surface gradually decreases. This is because the metakaolin composite limestone powder originally generates needle-shaped hydrated calcium aluminate and CASH gel in the cement hydration alkaline environment, and with the increase in the amount of potassium hydrogen phosphate and metakaolin, the carbon aluminate reaction is partially inhibited under the stimulation of potassium hydrogen phosphate, and the Al(OH) released after the metakaolin alkali dissolution in the early hydration process 4 − Produce calcium aluminum double hydroxide and AH 3 At the same time, the above reaction consumes the large-sized thin-plate Ca(OH) generated by cement hydration itself, which will cause the mortar to loosen. 2 , new hydration products (i.e. calcium aluminum double hydroxide, AH 3 The gel) interweaves with hydrated calcium aluminate and CASH gel to form a dense microstructure, which significantly reduces the porosity of the hardened mortar, making it difficult for water to pass through the mortar structure layer, thereby improving the anti-seepage ability of the thin layer mortar; at the same time, the overlapping and parallel special arrangement of layered double hydroxide crystals in the mortar hinders the passage of water molecules, and the AH in the pores 3Gel and CASH gel have strong hydrogen bond adsorption on water molecules, further hindering the diffusion of water molecules, thus achieving high impermeability and moisture-proof effect of thin-layer mortar, with the highest impermeability pressure reaching 1.1MPa in 7 days, and the lowest moisture content on the coating surface is only 1%. On the other hand, the layers in the layered double hydroxide crystal structure are bonded by weak van der Waals forces and electrostatic attraction. Alkaline substances can enter the interlayer of LDHs with water molecules and combine with anions and oxygen atoms in the interlayer to further increase the interlayer distance. At the same time, a large amount of alkaline substances are fixed in the interlayer through hydrogen bonds and hydration, thereby inhibiting the migration of alkaline substances in the base layer to the wall surface, achieving the effect of inhibiting the return of alkali in the base layer. There is no return of alkali and salt precipitation on the mortar surface of the back-water model for 90 days, the antibacterial rate is higher than 99%, and the mildew resistance level is 0.

[0066] Example 4 is a scheme in which gray cement and machine-made sand are replaced and the dosage of kaolin, limestone powder, glue powder, dipotassium hydrogen phosphate and other additives is increased. The test results show that the anti-seepage pressure of the mortar on the back water surface reaches 1.5MPa, the lateral deformation capacity is increased to 3.6mm, and the moisture content of the coating surface is as low as 0. This shows that by adjusting the dosage of key components, even with low-cost gray cement and machine-made sand, a higher-performance moisture-proof, mildew-proof and anti-seepage mortar for inhibiting alkali return of the base layer can be prepared.

[0067] Comparative Example 1 is a solution without adding kaolin. Compared with Example 1, due to the lack of kaolin, the Al(OH) 4 − The carbon aluminate reaction and the LDHs reaction cannot proceed, and the mortar structure has poor compactness. Therefore, the anti-seepage pressure of the mortar on the back water surface is significantly reduced, and is only 0.2MPa. At the same time, due to the inability to generate LDHs crystals, the key nanostructure is missing, the gel product is reduced, and the ability to solidify alkaline substances is lost. The moisture-proof, anti-seepage and alkali-reversion inhibition properties of this comparative example 1 are not good. The moisture content of the coating surface rises to 23%, and local alkali reversion occurs in 30 days, indicating that high-aluminum kaolin is the basis of the hydration product regulation technology of the present invention.

[0068] Comparative Example 2 is a solution without adding potassium hydrogen phosphate. Compared with Example 1, due to the presence of carbon aluminate reaction in the alkaline environment of hydration of metakaolin composite limestone cement, a large amount of Ca(OH) 2, and the generated needle-rod-shaped hydrated calcium aluminate and CASH gel also have a good effect on improving the density of the mortar structure, so the anti-seepage pressure of the mortar on the back water surface is only slightly reduced. However, due to the lack of potassium hydrogen phosphate, the kaolin cannot be stimulated to generate layered LDHs, and it does not have overlapping and parallel special arrangement nanostructures, sufficient gel adsorption and alkaline substance solidification effects. Therefore, the moisture-proof and alkali-resistant properties are general, the surface moisture content of the coating rises to 65%, and a large area of ​​alkali return occurs in 30 days, indicating that the stimulation of potassium hydrogen phosphate and the generation of LDHs crystals are the core of the moisture-proof and anti-seepage effect of the mortar of the present invention, and are also the key to distinguishing it from other existing technologies that use kaolin to improve the density of mortar.

[0069] Comparative Example 3 is a conventional commercially available moisture-proof and alkali-resistant polymer cement waterproof slurry. The test results show that its moisture-proof, anti-seepage and anti-alkali effects are very poor. Therefore, this material cannot be used for moisture-proofing of walls in indoor areas with potential leakage and dampness risks, nor can it be used for repairing the base of walls that have already peeled due to alkali reversion.

[0070] In summary, the present invention aims at the problem that the base layer of indoor building walls is prone to alkali return, which leads to moisture, peeling, mold and damage of the wall surface, and provides a moisture-proof, mildew-proof and anti-seepage mortar and construction method for inhibiting the return of base layer alkali. A single-component powder mortar solution is adopted, and only water needs to be added and stirred on site. The construction method of brushing or roller coating is adopted, which is simple and efficient, and can effectively cut off the water seepage channel of the base layer to achieve anti-seepage and moisture-proof. At the same time, alkaline substance solidification technology is used to inhibit the return of base layer alkali. While keeping the wall surface dry for a long time and the structure safe, the eradication of the mold breeding environment is achieved, thereby preventing the wall surface from mold. The mortar has an anti-bacterial rate of more than 99%, and a mildew resistance level of 0, which protects the wall surface coating as long as new and keeps the indoor wall surface and space healthy.

[0071] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A moisture-proof, mildew-proof and anti-seepage mortar for inhibiting alkali return of the base layer, characterized in that: The moisture-proof, mildew-proof and anti-seepage mortar is composed of raw materials including: common mortar raw materials and 30-60 parts of metakaolin, with a total amount of 1000 parts by weight; and 0.9-3 parts potassium hydrogen phosphate.

2. The moisture-proof, mildew-proof and anti-seepage mortar according to claim 1, characterized in that: The common mortar raw materials include: 400-600 parts of medium sand, 295-450 parts of common Portland cement, 15-30 parts of limestone powder, and 30-60 parts of redispersible latex powder.

3. The moisture-proof, mildew-proof and anti-seepage mortar according to claim 2 is characterized in that: The components of the moisture-proof, mildew-proof and anti-seepage mortar also include: 8-12 parts of water reducing agent and 1.1-3.2 parts of additives.

4. The moisture-proof, mildew-proof and anti-seepage mortar according to claim 3, characterized in that: The medium sand includes at least one of natural sand and artificial sand.

5. The moisture-proof, mildew-proof and anti-seepage mortar according to claim 3, characterized in that: The ordinary Portland cement includes at least one of gray cement and white cement.

6. The moisture-proof, mildew-proof and anti-seepage mortar according to claim 3, characterized in that: The potassium hydrogen phosphate includes at least one of dipotassium hydrogen phosphate and potassium dihydrogen phosphate; The particle size of the metakaolin is 1200-4000 mesh.

7. The moisture-proof, mildew-proof and anti-seepage mortar according to claim 3, characterized in that: The additives include: 0.5-2 parts of cellulose ether, 0.4-0.8 parts of water repellent, and 0.2-0.4 parts of defoaming agent.

8. A construction method for moisture-proof, mildew-proof and anti-seepage mortar according to any one of claims 1 to 7, characterized in that: include: Add water to the moisture-proof, mildew-proof and anti-seepage mortar as described in any one of claims 1 to 7, stir evenly, and then apply it on the surface of the base layer.

9. The construction method according to claim 8, characterized in that: In parts by weight, the mortar comprises 1000 parts, and the water comprises 220-250 parts.

10. The construction method according to claim 8, characterized in that: The base layer includes a concrete base layer or a cement mortar base layer.

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