High-strength gypsum-based self-leveling mortar for a surface layer and a method for preparing the same

Abstract

The application relates to the technical field of self-leveling mortar, in particular to high-strength gypsum-based self-leveling mortar for a surface layer and a preparation method thereof, which comprises the following raw materials in parts by weight: 300-400 parts of gypsum, 40-60 parts of cement, 30-50 parts of fly ash, 10-20 parts of a filler, 1-2 parts of a water reducing agent and 0.5-1 part of a defoaming agent. In the application, the powder is a core aggregate component in the first additive, hydroxypropyl methyl cellulose can provide adhesion and, as an organic phase skeleton, can enhance the toughness of the whole material after combination, dodecylamine can improve the compatibility among the materials as an active agent, nano silicon dioxide can play a filling role to make the stress transmission among the materials uniform, and lithium smectite can generate a thickening network by combining with hydroxypropyl methyl cellulose and hydroxymethyl chitosan by virtue of its colloid property, so that the overall strength performance of the self-leveling mortar is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of self-leveling mortar, in particular to a high-strength gypsum-based self-leveling mortar for surface layer and a preparation method thereof. BACKGROUND

[0002] The gypsum-based self-leveling mortar is a kind of material with good fluidity after being stirred with water, which can automatically level and form a flat surface, and is suitable for ground engineering of houses, commercial places and the like, and is a commonly used material for modern ground decoration.

[0003] In the prior art, the overall mechanical property of the gypsum-based self-leveling mortar is poor, and the compressive and flexural strength performance after forming is poor, which affects the popularization and use of the gypsum-based self-leveling mortar. Based on this, the present application provides a high-strength gypsum-based self-leveling mortar for surface layer and a preparation method thereof. SUMMARY

[0004] The present application aims to provide a high-strength gypsum-based self-leveling mortar for surface layer and a preparation method thereof. The high-strength gypsum-based self-leveling mortar for surface layer prepared by the present application not only has good compressive strength performance, but also has excellent flexural strength performance, effectively improving the use performance of the high-strength gypsum-based self-leveling mortar for surface layer.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0006] In a first aspect, the present application provides a high-strength gypsum-based self-leveling mortar for surface layer, which comprises the following raw materials by weight: 300-400 parts of gypsum, 40-60 parts of cement, 30-50 parts of fly ash, 10-20 parts of filler, 1-2 parts of water reducing agent, and 0.5-1 part of defoaming agent.

[0007] The filler is prepared by the following method:

[0008] S1: First additive preparation, the raw materials of the first additive include powder, hectorite, hydroxymethyl chitosan, phosphate buffer, and methacrylic anhydride;

[0009] S2: Second additive preparation, the raw materials of the second additive include butane tetracarboxylic acid, urea, acetylacetone aluminum, tetraethylenepentamine solution, and acacia solution;

[0010] S3: Mixing treatment, the first additive and the second additive are mixed and treated at 60-100 rpm for 20-40 min to prepare the filler.

[0011] Further, the method for preparing the first additive is as follows: the powder, lithium smectite, hydroxymethyl chitosan, and phosphate buffer are added into a reaction kettle, the temperature of the reaction kettle is set to 40-50℃, the stirring speed is set to 200-400 rpm, and constant temperature stirring treatment is performed for 40-60 min; after the constant temperature stirring treatment is completed, methyl methacrylate is added into the reaction kettle, the reaction kettle continues constant temperature stirring treatment for 10-20 min; the obtained product is added into a centrifuge, the centrifuge is set to 8000-10000 rpm for centrifugal treatment for 6-10 min, the precipitate is obtained from the centrifuged product, the precipitate is washed with deionized water, and then is added into an oven, the oven is set to 50-70℃ for drying treatment for 4-6 h, and the first additive is prepared.

[0012] Further, the mass ratio of the powder, lithium smectite, hydroxymethyl chitosan, and phosphate buffer is 1:(0.2-0.4):(0.1-0.2):(4-6), the mass of methyl methacrylate is 2-4% of the mass of the powder, and the mass concentration of the phosphate buffer is 0.6-1 g / L.

[0013] Further, the powder is prepared by the following method: hydroxypropyl methyl cellulose, dodecylamine, anhydrous ethanol, deionized water, tetraethyl orthosilicate, and ammonia are added into a mixer, the mixer is set to a rotating speed of 100-200 rpm, and stirring treatment is performed at room temperature for 4-6 h; methyl methacrylate is added into the mixer, and stirring treatment is performed at a rotating speed of 200-400 rpm for 20-40 min; the obtained product is subjected to distillation treatment to remove the anhydrous ethanol, and a mixture is obtained; the mixture, KH560, and nanosilica are added into the mixer, the mixer is set to a rotating speed of 400-600 rpm, and stirring treatment is performed at room temperature for 2-4 h; the obtained product is subjected to filtration treatment to obtain a solid, and the solid is added into an oven, the oven is set to 40-60℃ for drying treatment for 4-6 h, and the powder is prepared.

[0014] Further, the mass ratio of the hydroxypropyl methyl cellulose, dodecylamine, anhydrous ethanol, deionized water, tetraethyl orthosilicate, and ammonia is 1:(0.1-0.2):(0.4-0.6):(6-8):(0.06-0.08):(0.1-0.2), the mass of the methyl methacrylate is 8-10% of the mass of the hydroxypropyl methyl cellulose, and the mass concentration of the ammonia is 6-10%.

[0015] Further, the second additive is prepared by the following method: butane tetracarboxylic acid, urea, aluminum acetylacetone are added into a mixer, the mixer is set to stir at 400-600 r / min for 40-60 min, the obtained product is added into a reaction kettle, tetraethylenepentamine solution and gum arabic solution are added into the reaction kettle, the reaction kettle is set to a temperature of 60-80 DEG C, the stirring speed is 60-100 rpm, constant temperature stirring is carried out for 30-50 min, the obtained product is subjected to ultrasonic dispersion treatment, and the second additive is prepared.

[0016] Further, the mass ratio of butane tetracarboxylic acid, urea and aluminum acetylacetone is 1:(2-4):(0.6-0.8), the mass of the tetraethylenepentamine solution is 10-20% of the mass of the butane tetracarboxylic acid, the mass of the gum arabic solution is 3-4 times of the mass of the tetraethylenepentamine solution, the mass concentration of the tetraethylenepentamine solution is 10-20%, and the mass concentration of the gum arabic solution is 3-5%.

[0017] Further, the gypsum is selected from alpha high-strength microcrystalline gypsum, and the cement is selected from calcium aluminate cement.

[0018] Further, the defoaming agent is selected from an organic silicon defoaming agent, and the water reducing agent is selected from a polycarboxylic acid water reducing agent.

[0019] In the second aspect, the application further provides a preparation method of the high-strength gypsum-based self-leveling mortar for a surface layer, which comprises the following steps: weighing gypsum, cement, fly ash, filler, water reducing agent and defoaming agent according to requirements, and adding them into a mortar mixer, stirring at 80-120 rpm for 30-50 min to obtain dry materials, adding water with a mass of 25-35% of the dry materials into the mortar mixer, and stirring at 20-40 rpm for 8-12 min to prepare the high-strength gypsum-based self-leveling mortar for a surface layer.

[0020] Compared with the prior art, the application has the following beneficial effects:

[0021] 1. In the preparation of the gypsum-based self-leveling mortar, the powder is used as the core aggregate component in the first additive, the hydroxypropyl methyl cellulose can provide adhesion and serve as an organic phase skeleton to enhance the toughness of the combined material, the dodecylamine can improve the compatibility between the materials, the nano silicon dioxide can fill the materials to make the stress transfer uniform, and the hectorite can combine with the hydroxypropyl methyl cellulose and the hydroxymethyl chitosan to form a thickening network to improve the overall strength performance of the self-leveling mortar.

[0022] 2、In the application, the hydroxymethyl chitosan as a natural polymer material, the hydroxyl and amino on the molecular chain can form hydrogen bond with the hydroxyl of the hectorite and the powder, and coordinate with the interlayer lithium ion of the hectorite, so that better bonding effect is achieved, the binding strength of the material is improved, the methacrylic anhydride can react with the amino of the hydroxymethyl chitosan to enhance the reaction activity of the first additive in the mixing of raw materials, and the tetraethylenepentamine can also form a binding network with the gum arabic to improve the overall strength performance of the self-leveling mortar. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A formula chart of a high-strength gypsum-based self-leveling mortar for a surface layer and a preparation method thereof are provided. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the application will be apparently and completely described below with reference to the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0025] It should be noted that the raw materials used in the following embodiments are commercially available.

[0026] Embodiment one:

[0027] Preparation of raw materials:

[0028] 400 parts of gypsum, 60 parts of cement, 50 parts of fly ash, 20 parts of filler, 2 parts of water reducing agent, and 1 part of defoaming agent;

[0029] The gypsum is selected from alpha high-strength microcrystalline gypsum, the cement is selected from calcium aluminate cement, the defoaming agent is selected from organic silicon defoaming agent, and the water reducing agent is selected from polycarboxylic acid type water reducing agent.

[0030] Preparation of filler:

[0031] S1: Preparation of the first additive, the raw materials of the first additive include powder, hectorite, hydroxymethyl chitosan, phosphate buffer, and methacrylic anhydride;

[0032] The first additive is prepared by the following method: powder, hectorite, hydroxymethyl chitosan, phosphate buffer are added into a reaction kettle, the reaction kettle is set to 50°C, the stirring speed is 400 rpm, and constant temperature stirring treatment is performed for 60 min; after the constant temperature stirring treatment is completed, methyl methacrylate is added into the reaction kettle, the reaction kettle continues constant temperature stirring treatment for 20 min; the obtained product is added into a centrifuge, the centrifuge is set to 10000 rpm for centrifugal treatment for 10 min; the precipitate is obtained from the centrifuged product, deionized water is used for washing treatment of the precipitate, and then the precipitate is added into an oven, the oven is set to 70°C for drying treatment for 6 h, and the first additive is prepared; wherein, the mass ratio of the powder, hectorite, hydroxymethyl chitosan and phosphate buffer is 1:0.4:0.2:6, the mass of methyl methacrylate is 2% of the mass of the powder, and the mass concentration of the phosphate buffer is 1 g / L;

[0033] Preparation of the powder:

[0034] Hydroxypropyl methyl cellulose, dodecylamine, anhydrous ethanol, deionized water, tetraethyl orthosilicate, ammonia are added into a mixer, the mixer is set to 200 rpm, and stirring treatment is performed at room temperature for 6 h; methyl methacrylate is added into the mixer, and stirring treatment is performed at 400 rpm for 40 min; the obtained product is subjected to distillation treatment to remove anhydrous ethanol, and a mixture is obtained; the mixture, KH560 and nano-silicon dioxide are added into the mixer, the mixer is set to 600 rpm, and stirring treatment is performed at room temperature for 4 h; the obtained product is subjected to filtration treatment to obtain a solid; the solid is added into an oven, the oven is set to 60°C for drying treatment for 6 h, and the powder is prepared; wherein, the mass ratio of hydroxypropyl methyl cellulose, dodecylamine, anhydrous ethanol, deionized water, tetraethyl orthosilicate and ammonia is 1:0.2:0.6:8:0.08:0.2, the mass of methyl methacrylate is 10% of the mass of hydroxypropyl methyl cellulose, and the mass ratio of the mixture, KH560 and nano-silicon dioxide is 1:0.04:0.08; the mass concentration of ammonia is 10%;

[0035] S2: preparation of the second additive, the raw materials of the second additive include butane tetracarboxylic acid, urea, acetylacetone aluminum, tetraethylenepentamine solution and acacia solution;

[0036] The second additive is prepared by the following method: butane tetracarboxylic acid, urea, aluminum acetylacetone are added into a mixer, the mixer is set to 600 r / min stirring treatment for 60 min, the obtained product is added into a reaction kettle, tetraethylene pentamine solution and gum arabic solution are added into the reaction kettle, the reaction kettle is set to 80℃, the stirring speed is 100 rpm, constant temperature stirring treatment is carried out for 50 min, the obtained product is subjected to ultrasonic dispersion treatment, and the second additive is prepared, wherein the mass ratio of butane tetracarboxylic acid, urea and aluminum acetylacetone is 1:4:0.8, the mass of the tetraethylene pentamine solution is 20% of the mass of the butane tetracarboxylic acid, the mass of the gum arabic solution is 4 times the mass of the tetraethylene pentamine solution, the mass concentration of the tetraethylene pentamine solution is 20%, and the mass concentration of the gum arabic solution is 5%;

[0037] S3: mixing treatment, the first additive and the second additive are mixed at 100 rpm for 40 min to prepare the filler;

[0038] Finished product preparation:

[0039] The gypsum, cement, fly ash, filler, water reducing agent and defoaming agent are weighed as required and added into a mortar mixer, and stirred at 120 rpm for 50 min to obtain dry materials, and then 35% of the mass of the dry materials is added into the mortar mixer, and stirred at 40 rpm for 12 min to prepare the surface layer high-strength gypsum-based self-leveling mortar.

[0040] Example two:

[0041] Raw material preparation:

[0042] 300 parts of gypsum, 40 parts of cement, 30 parts of fly ash, 10 parts of filler, 1 part of water reducing agent and 0.5 part of defoaming agent;

[0043] The gypsum is selected from α high-strength microcrystalline gypsum, the cement is selected from calcium aluminate cement, the defoaming agent is selected from organic silicon defoaming agent, and the water reducing agent is selected from polycarboxylic acid water reducing agent;

[0044] Preparation of the filler:

[0045] S1: preparation of the first additive, the raw materials of the first additive include powder, lithium smectite, hydroxymethyl chitosan, phosphate buffer solution and methacrylic anhydride;

[0046] The first additive is prepared by the following method: powder, hectorite, hydroxymethyl chitosan, phosphate buffer are added into a reaction kettle, the reaction kettle is set to 40°C, the stirring speed is 200 rpm, and constant temperature stirring treatment is performed for 40 min. After completing the constant temperature stirring treatment, methyl methacrylate is added into the reaction kettle, the reaction kettle continues constant temperature stirring treatment for 10 min, the obtained product is added into a centrifuge, the centrifuge is set to 8000 rpm for centrifugal treatment for 6 min, the precipitate is obtained from the centrifuged product, the precipitate is washed with deionized water, and then is added into an oven, the oven is set to 50°C for drying treatment for 4 h, to obtain the first additive. The mass ratio of the powder, hectorite, hydroxymethyl chitosan and phosphate buffer is 1:0.2:0.1:4, the mass of methyl methacrylate is 2% of the mass of the powder, and the mass concentration of the phosphate buffer is 0.6 g / L.

[0047] Preparation of the powder:

[0048] Hydroxypropyl methyl cellulose, dodecylamine, anhydrous ethanol, deionized water, tetraethyl orthosilicate, ammonia are added into a mixer, the mixer is set to 100 rpm, and stirring treatment is performed at room temperature for 4 h. Methyl methacrylate is added into the mixer, and stirring treatment is performed at 200 rpm for 20 min. The obtained product is subjected to distillation treatment to remove anhydrous ethanol, to obtain a mixture. The mixture, KH560 and nano-silicon dioxide are added into the mixer, the mixer is set to 400 rpm, and stirring treatment is performed at room temperature for 2 h. The obtained product is subjected to filtration treatment to obtain a solid. The solid is added into an oven, the oven is set to 40°C for drying treatment for 4 h, to obtain the powder. The mass ratio of the hydroxypropyl methyl cellulose, dodecylamine, anhydrous ethanol, deionized water, tetraethyl orthosilicate and ammonia is 1:0.1:0.4:6:0.06:0.1, the mass of the methyl methacrylate is 8% of the mass of the hydroxypropyl methyl cellulose, and the mass ratio of the mixture, KH560 and nano-silicon dioxide is 1:0.02:0.06. The mass concentration of the ammonia is 6%.

[0049] S2: Preparation of the second additive, the raw materials of the second additive include butane tetracarboxylic acid, urea, acetylacetone aluminum, tetraethylenepentamine solution and acacia solution.

[0050] The second additive is prepared by the following method: butane tetracarboxylic acid, urea, aluminum acetylacetone are added into a mixer, the mixer is set to 400 r / min stirring treatment for 40 min, the obtained product is added into a reaction kettle, tetraethylene pentamine solution and gum arabic solution are added into the reaction kettle, the reaction kettle is set to 60℃, the stirring speed is 60 rpm, constant temperature stirring treatment is carried out for 30 min, the obtained product is subjected to ultrasonic dispersion treatment, and the second additive is prepared, wherein the mass ratio of butane tetracarboxylic acid, urea and aluminum acetylacetone is 1:2:0.6, the mass of the tetraethylene pentamine solution is 10% of the mass of the butane tetracarboxylic acid, the mass of the gum arabic solution is 3 times of the mass of the tetraethylene pentamine solution, the mass concentration of the tetraethylene pentamine solution is 10%, and the mass concentration of the gum arabic solution is 3%;

[0051] S3: mixing treatment, the first additive and the second additive are mixed at 60 rpm for 20 min to prepare the filler;

[0052] Finished product preparation:

[0053] The gypsum, cement, fly ash, filler, water reducing agent and defoaming agent are weighed as required and added into a mortar mixer, and stirred at 80 rpm for 30 min to obtain dry materials, and then 25% of water by mass of the dry materials is added into the mortar mixer and stirred at 20 rpm for 8 min to prepare the surface layer high-strength gypsum-based self-leveling mortar.

[0054] Example three:

[0055] Raw material preparation:

[0056] 350 parts of gypsum, 50 parts of cement, 40 parts of fly ash, 15 parts of filler, 1.5 parts of water reducing agent and 0.7 parts of defoaming agent;

[0057] The gypsum is selected from α high-strength microcrystalline gypsum, the cement is selected from calcium aluminate cement, the defoaming agent is selected from organic silicon defoaming agent, and the water reducing agent is selected from polycarboxylic acid type water reducing agent;

[0058] Preparation of the filler:

[0059] S1: preparation of the first additive, the raw materials of the first additive include powder, lithium smectite, hydroxymethyl chitosan, phosphate buffer solution and methacrylic anhydride;

[0060] The first additive is prepared by the following method: powder, hectorite, hydroxymethyl chitosan, phosphate buffer are added into a reaction kettle, the reaction kettle is set to 45°C, the stirring speed is 300 rpm, and constant temperature stirring treatment is performed for 50 min. After completing the constant temperature stirring treatment, methyl methacrylate is added into the reaction kettle, the reaction kettle continues constant temperature stirring treatment for 15 min, the obtained product is added into a centrifuge, the centrifuge is set to 9000 rpm for centrifugal treatment for 8 min, the precipitate is obtained from the centrifuged product, the precipitate is washed with deionized water, and then is added into an oven, the oven is set to 60°C for drying treatment for 5 h, to obtain the first additive. The mass ratio of the powder, hectorite, hydroxymethyl chitosan and phosphate buffer is 1:0.3:0.15:5, the mass of methyl methacrylate is 3% of the mass of the powder, and the mass concentration of the phosphate buffer is 0.8 g / L.

[0061] Preparation of the powder:

[0062] Hydroxypropyl methyl cellulose, dodecylamine, anhydrous ethanol, deionized water, tetraethyl orthosilicate, ammonia are added into a mixer, the mixer is set to 150 rpm, and stirring treatment is performed at room temperature for 5 h. Methyl methacrylate is added into the mixer, and stirring treatment is performed at 300 rpm for 30 min. The obtained product is subjected to distillation treatment to remove anhydrous ethanol, to obtain a mixture. The mixture, KH560 and nano-silicon dioxide are added into the mixer, the mixer is set to 50 rpm, and stirring treatment is performed at room temperature for 3 h. The obtained product is subjected to filtration treatment to obtain a solid. The solid is added into an oven, the oven is set to 50°C for drying treatment for 5 h, to obtain the powder. The mass ratio of the hydroxypropyl methyl cellulose, dodecylamine, anhydrous ethanol, deionized water, tetraethyl orthosilicate and ammonia is 1:0.15:0.5:7:0.07:0.15, the mass of the methyl methacrylate is 9% of the mass of the hydroxypropyl methyl cellulose, and the mass ratio of the mixture, KH560 and nano-silicon dioxide is 1:0.03:0.07. The mass concentration of the ammonia is 8%.

[0063] S2: Preparation of the second additive, the raw materials of the second additive include butane tetracarboxylic acid, urea, acetylacetone aluminum, tetraethylenepentamine solution and acacia solution.

[0064] The second additive is prepared by the following method: butane tetracarboxylic acid, urea, aluminum acetylacetone are added into a mixer, the mixer is set to 500 r / min stirring treatment for 50 min, the obtained product is added into a reaction kettle, tetraethylenepentamine solution and gum arabic solution are added into the reaction kettle, the reaction kettle is set to 70℃, the stirring speed is 80 rpm, constant temperature stirring treatment is carried out for 40 min, the obtained product is subjected to ultrasonic dispersion treatment, and the second additive is prepared.

[0065] S3: mixing treatment, the first additive and the second additive are mixed at 80 rpm for 30 min, and the filler is prepared.

[0066] Product preparation:

[0067] The gypsum, cement, fly ash, filler, water reducing agent and defoaming agent are weighed as required and added into a mortar mixer, and stirred at 100 rpm for 40 min to obtain dry materials, and then 30% of water of the dry materials is added into the mortar mixer and stirred at 30 rpm for 10 min to prepare the surface layer high-strength gypsum-based self-leveling mortar.

[0068] Comparative Example 1, the difference between the comparative example and example 1 is that the powder in the comparative example.

[0069] Comparative Example 2, the difference between the comparative example and example 1 is that the first additive is not contained in the comparative example, that is, an equal amount of the second additive is used to replace the filler.

[0070] Comparative Example 3, the difference between the comparative example and example 1 is that the filler is not contained in the comparative example.

[0071] Performance test: the surface layer high-strength gypsum-based self-leveling mortar prepared in example 1, example 2, example 3, comparative example 1, comparative example 2, comparative example 3 and comparative example 4 is subjected to performance test, and the obtained test data are recorded in the following table:

[0072] Table 1

[0073]

[0074]

[0075] In the performance test, according to the test standard in JC / T1023-2021, the high-strength gypsum-based self-leveling mortar for a surface layer prepared by using Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 is used to prepare samples with a size of 40mm*40mm*160mm, and the samples are tested for 28d compressive strength and 28d flexural strength.

[0076] It can be seen that the compressive strength and flexural strength data of the high-strength gypsum-based self-leveling mortar for a surface layer prepared by Comparative Examples 1, 2, 3 and 4 are lower than those of Examples 1, 2 and 3; this shows that, in the preparation of the gypsum-based self-leveling mortar, the powder is the core aggregate component in the first additive, the hydroxypropyl methyl cellulose can provide adhesion and, as an organic phase skeleton, enhance the toughness of the combined material, the dodecylamine can improve the compatibility between the materials, the nanometer silicon dioxide can play a filling role to make the stress transfer between the materials uniform, and the hectorite can form a thickening network with the hydroxypropyl methyl cellulose and the hydroxymethyl chitosan by using its colloid property, thereby improving the overall strength performance of the self-leveling mortar;

[0077] The hydroxymethyl chitosan, as a natural polymer material, can form hydrogen bonds with the hydroxyl groups of the hectorite and the powder and coordinate with the lithium ions between the layers of the hectorite by the hydroxyl and amino groups on the molecular chain, thereby playing a good adhesion role and improving the bonding strength of the material, the methacrylic anhydride can react with the amino groups of the hydroxymethyl chitosan to enhance the reactivity of the first additive in the mixing of the raw materials, and the tetraethylenepentamine can also form a binding network with the gum arabic to improve the overall strength performance of the self-leveling mortar.

[0078] As can be seen from the comparison and analysis of the related data in the table, the high-strength gypsum-based self-leveling mortar for a surface layer prepared by the application not only has good compressive strength performance, but also has excellent flexural strength performance. This shows that the high-strength gypsum-based self-leveling mortar for a surface layer provided by the application has a broader market prospect and is more suitable for promotion.

[0079] In the description of the present specification, the description of the terms "one embodiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0080] The preferred embodiments of the application disclosed above are only to facilitate the elucidation of the application. The preferred embodiments do not describe all the details of the application and limit the application to the specific embodiments described. Obviously, many modifications and variations can be made in light of the teachings above. The description is chosen and described in order to best explain the principles of the application and its practical application to thereby enable others skilled in the art to best utilize the application and get the best results from the application. The application is only limited by the claims and their full scope and equivalents.

Claims

1. A high-strength gypsum-based self-leveling mortar for surface layer, characterized in that: The raw materials include the following parts by weight: 300-400 parts gypsum, 40-60 parts cement, 30-50 parts fly ash, 10-20 parts filler, 1-2 parts water-reducing agent, and 0.5-1 part defoamer; The filler is prepared by the following method: S1: Preparation of the first additive, the raw materials of the first additive include powder, lithium saponite, hydroxymethyl chitosan, phosphate buffer, and methacrylic anhydride; The powder is prepared by the following method: Hydroxypropyl methylcellulose, dodecylamine, anhydrous ethanol, deionized water, tetraethyl orthosilicate, and ammonia are added to a mixer, the mixer is set to a speed of 100-200 rpm, and stirred at room temperature for 4-6 hours. Methyl methacrylate is added to the mixer, and the mixture is stirred at 200-400 rpm for 20-40 minutes. The resulting product is distilled to remove anhydrous ethanol, resulting in a mixture. The mixture, KH560, and nano-silica are added to a mixer, the mixer is set to a speed of 400-600 rpm, and stirred at room temperature for 2-4 hours. The resulting product is filtered to obtain a solid. The solid is added to an oven and dried at 40-60°C for 4-6 hours to obtain the powder. S2: Preparation of the second additive, the raw materials of the second additive include butanetetracarboxylic acid, urea, aluminum acetylacetonate, tetraethylenepentamine solution, and gum arabic solution; S3: Mixing treatment, the first additive and the second additive are mixed at 60-100 rpm for 20-40 min to obtain the filler; The method for preparing the first additive is as follows: powder, lithium saponite, hydroxymethyl chitosan, and phosphate buffer are added to a reaction vessel. The reaction vessel is set to a temperature of 40-50°C and a stirring speed of 200-400 rpm. The mixture is kept at a constant temperature and stirred for 40-60 minutes. After the constant temperature stirring is completed, methacrylic anhydride is added to the reaction vessel. The reaction vessel is kept at a constant temperature and stirred for 10-20 minutes. The resulting product is added to a centrifuge and centrifuged at 8000-10000 rpm for 6-10 minutes. A precipitate is obtained from the centrifuged product. The precipitate is washed with deionized water and then placed in an oven and dried at 50-70°C for 4-6 hours to obtain the first additive. The second additive is prepared by the following method: butanetetracarboxylic acid, urea, and aluminum acetylacetonate are added to a mixer, which is set to 400-600 r / min and stirred for 40-60 min. The resulting product is added to a reaction vessel, where tetraethylenepentamine solution and gum arabic solution are added. The reaction vessel is set to a temperature of 60-80°C and a stirring speed of 60-100 rpm. The mixture is stirred at a constant temperature for 30-50 min. The resulting product is then subjected to ultrasonic dispersion to obtain the second additive.

2. The high-strength gypsum-based self-leveling mortar for surface layer according to claim 1, characterized in that, The mass ratio of powder, lithium saponite, hydroxymethyl chitosan, and phosphate buffer is 1:(0.2-0.4):(0.1-0.2):(4-6), the mass of methacrylic anhydride is 2-4% of the mass of powder, and the mass concentration of phosphate buffer is 0.6-1 g / L.

3. The high-strength gypsum-based self-leveling mortar for surface layer according to claim 1, characterized in that, The mass ratio of hydroxypropyl methylcellulose, dodecylamine, anhydrous ethanol, deionized water, tetraethyl orthosilicate, and ammonia is 1:(0.1-0.2):(0.4-0.6):(6-8):(0.06-0.08):(0.1-0.2). The mass of methyl methacrylate is 8-10% of the mass of hydroxypropyl methylcellulose. The mass ratio of the mixture, KH560, and nano silica is 1:(0.02-0.04):(0.06-0.08). The mass concentration of ammonia is 6-10%.

4. The high-strength gypsum-based self-leveling mortar for surface layer according to claim 1, characterized in that, The mass ratio of butanetetracarboxylic acid, urea, and aluminum acetylacetone is 1:(2-4):(0.6-0.8). The mass of the tetraethylenepentamine solution is 10-20% of the mass of the butanetetracarboxylic acid solution, the mass of the gum arabic solution is 3-4 times the mass of the tetraethylenepentamine solution, the mass concentration of the tetraethylenepentamine solution is 10-20%, and the mass concentration of the gum arabic solution is 3-5%.

5. The high-strength gypsum-based self-leveling mortar for surface layer according to claim 1, characterized in that, The gypsum is selected as α-high-strength microcrystalline gypsum, and the cement is selected as calcium aluminate cement.

6. The high-strength gypsum-based self-leveling mortar for surface layer according to claim 1, characterized in that, The defoamer is a silicone defoamer, and the water-reducing agent is a polycarboxylate-based water-reducing agent.

7. A method for preparing high-strength gypsum-based self-leveling mortar for surface layer according to any one of claims 1 to 6, characterized in that, The process includes the following steps: Weigh out gypsum, cement, fly ash, filler, water-reducing agent, and defoamer as needed and add them to a mortar mixer. Mix at 80-120 rpm for 30-50 minutes to obtain dry material. Add water at 25-35% of the dry material mass to the mortar mixer and mix at 20-40 rpm for 8-12 minutes to obtain high-strength gypsum-based self-leveling mortar for surface layer.

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