Self-leveling mortar and its preparation method

Abstract

The present invention provides a self-leveling mortar and a preparation method thereof, which relates to the technical field of mortar manufacturing. The preparation method of the self-leveling mortar includes: uniformly mixing gypsum, cement, river sand, inorganic filler, and carbon fiber to obtain a mixture; uniformly mixing a defoaming agent, a water reducing agent, a retarder, a stabilizer, and a flow aid to obtain a composite additive; while stirring the mixture, uniformly adding the composite additive to the mixture at a constant speed and maintaining stirring until the mixture and the composite additive are uniformly mixed to obtain the self-leveling mortar. The self-leveling mortar prepared by the present invention has good compressive strength and durability due to the addition of inorganic filler. In addition, the self-leveling mortar prepared by the present invention also has the advantage of not being easily cracked due to the addition of carbon fiber. Finally, when the self-leveling mortar prepared by the present invention is prepared and used by adding water, it is not prone to bleeding and delamination, and has good uniformity and stability.

Description

Technical Field

[0001] The present invention relates to the technical field of mortar manufacturing, and more particularly, to a self-leveling mortar and a preparation method thereof. Background Art

[0002] Self-leveling mortar is a self-leveling foundation material with strong fluidity and high plasticity formed by mixing cement, aggregates, various additives and water, and is widely applicable to the fine leveling scenario of concrete floors. Among them, gypsum-based self-leveling mortar has the characteristics of good self-leveling property, reducible manual trimming and smooth surface, so it has good market prospects. However, the disadvantage of gypsum-based self-leveling mortar is its low strength.

[0003] The prior art generally improves the strength (especially the compressive strength) of self-leveling mortar by adding inorganic fillers to the raw materials of self-leveling mortar. For example, inorganic powders such as silicon oxide and aluminum oxide, as well as ceramic microspheres such as silicon carbide and silicon nitride, can be used as inorganic fillers added to self-leveling mortar.

[0004] There are two common problems with inorganic fillers in the prior art. One is that the density of inorganic fillers is generally relatively large, and the other is that the specific surface area of inorganic fillers is large, the surface energy is high, and the hydrophilic property is poor. The above problems result in that after the self-leveling mortar is prepared by adding water, the inorganic fillers therein cannot be uniformly and stably dispersed, and it is easy to agglomerate and settle at the bottom of the mortar, resulting in the problems of bleeding, delamination and non-uniformity of the self-leveling mortar. Summary of the Invention

[0005] The problem to be solved by the present invention is how to provide a self-leveling mortar with relatively high compressive strength and not prone to bleeding, delamination and non-uniformity problems.

[0006] To solve the above problems, the present invention provides a preparation method of a self-leveling mortar, and the preparation method includes:

[0007] S100. Mix and stir gypsum, cement, river sand and inorganic filler evenly according to the mass ratio of gypsum:cement:river sand:inorganic filler = (55-60):(10-15):(10-15):(10-15) to obtain a mixture;

[0008] S200. Mix and stir a defoaming agent, a water reducing agent, a retarder, a stabilizer and a flow aid evenly according to the mass ratio of defoaming agent:water reducing agent:retarder:stabilizer:flow aid = (1-2):(1.2-1.5):(0.4-0.5):(0.4-0.5) to obtain a composite additive;

[0009] S300. While stirring the mixture, add the composite additive to the mixture at a mass ratio of composite additive: mixture = (3 - 4.5): 100 in a uniform speed and keep stirring until the mixture and the composite additive are uniformly mixed to obtain self-leveling mortar;

[0010] Among them, the preparation method of the inorganic filler includes:

[0011] S410. Mix silicon carbide powder, aluminum hydroxide powder, chitosan, yttrium oxide, titanium carbide, and sodium hexametaphosphate evenly in ethanol to obtain a slurry;

[0012] S420. Grind the slurry evenly by wet grinding. After grinding, take out the slurry for filtration, washing, and drying to obtain a powder;

[0013] S430. Calcinate the powder. After the calcination is completed, cool it with the furnace and grind it to obtain silicon carbide ceramic powder;

[0014] S440. Use raw materials including silicon carbide ceramic powder and montmorillonite to prepare inorganic filler by hydrothermal method.

[0015] Further, in S410, calculated by mass ratio, silicon carbide powder: aluminum hydroxide powder: chitosan: yttrium oxide: titanium carbide: sodium hexametaphosphate: ethanol = (40 - 45): (5 - 10): (4 - 6): (1 - 2): (0.5 - 1): (0.5 - 1): 100.

[0016] Further, in S420, the process parameters of wet grinding include: using zirconia balls as grinding media and grinding at a speed of 350 rpm - 400 rpm for 20 min - 30 min.

[0017] Further, in S430, the process parameters of calcination include: calcining at a temperature of 2150 °C - 2250 °C for 1 h - 2 h.

[0018] Further, S440 includes:

[0019] S441. Mix tetrabutyl titanate, montmorillonite, polyvinylpyrrolidone, and acetylacetone evenly in water, gradually add ethanol with a mass twice that of water and stir synchronously. After the addition is completed, let it stand for 0.5 h - 1 h to obtain a sol mixture;

[0020] S442. Mix the sol mixture and silicon carbide ceramic powder evenly and send them into a reaction kettle. After adding alkali to adjust the pH value to 9 - 10, heat and pressurize for hydrothermal reaction. After the reaction is completed, relieve the temperature and pressure, extract the solid matter for filtration and drying to obtain a precursor;

[0021] S443. Calcinate the precursor, cool it in the furnace after calcination, grind and crush it to obtain the inorganic filler.

[0022] Further, in S441, calculated by mass ratio, tetrabutyl titanate: montmorillonite: polyvinylpyrrolidone: acetylacetone: water = (10 - 15):(20 - 30):(6 - 8):(8 - 10):100.

[0023] Further, in S442, calculated by mass ratio, the sol mixture: silicon carbide ceramic powder = (20 - 30):100.

[0024] Further, in S442, the process parameters of the hydrothermal reaction include: carrying out the hydrothermal reaction for 2 h - 2.5 h under the temperature condition of 140°C - 160°C and the pressure condition of 5 MPa - 7 MPa.

[0025] Further, in S443, the process parameters of the calcination include: calcining at the temperature condition of 450°C - 550°C for 1 h - 2 h.

[0026] Further, the defoamer includes at least one of the following or a combination thereof: Sago - 1667 defoamer, Sago - 1886 defoamer, Modaflow9200 defoamer.

[0027] Further, the water - reducing agent includes at least one of the following or a combination thereof: sodium tripolyphosphate water - reducing agent, sodium ethylenediaminetetraacetate water - reducing agent, sodium iminotriacetate water - reducing agent.

[0028] Further, the setting retarder includes at least one of the following or a combination thereof: sodium gluconate setting retarder, sodium ethylenediaminetetraacetate setting retarder, sodium tartrate setting retarder, sodium borate setting retarder, aluminum sulfate setting retarder.

[0029] Further, the stabilizer includes at least one of the following or a combination thereof: polyvinyl alcohol stabilizer, guar gum stabilizer, sodium alginate stabilizer.

[0030] Further, the glidant includes at least one of the following or a combination thereof: sodium stearate glidant, magnesium stearate glidant, potassium stearate glidant, talc powder glidant, magnesium silicate glidant.

[0031] Further, the defoamer is Sago - 1667 defoamer, the water - reducing agent is sodium iminotriacetate, the setting retarder is sodium tartrate setting retarder, the stabilizer is guar gum stabilizer, and the glidant is magnesium stearate glidant.

[0032] Further, after S440, the preparation method of the inorganic filler further includes:

[0033] S450. Modify the inorganic filler with a hydrophilic polyether polymer material.

[0034] Further, S450 specifically includes:

[0035] S451. Under nitrogen protection, add ammonia water, pentaerythritol, and 3-aminopropyltrimethoxysilane into a reaction kettle and mix evenly. Heat the reaction kettle to 55°C - 60°C, then add propylene oxide and ethylene oxide. React for 0.5 h - 1 h under a vacuum pressure condition and a temperature condition of 100°C - 105°C. After the reaction ends, cool the reaction kettle to 80°C - 90°C and adjust the pH to neutral with acid. Subsequently, add isophorone diisocyanate to the reaction kettle and continue the heat preservation reaction for 1 h - 1.5 h. After the reaction ends, cool to obtain a prepolymer;

[0036] S452. Mix glycerol, dimethylolpropionic acid, xanthan gum, the prepolymer, and inorganic filler in a reaction kettle, and react for 2 h - 2.5 h under a temperature condition of 90°C - 95°C. After the reaction ends, extract the solid matter and dry it to obtain the modified inorganic filler.

[0037] Further, in S451, calculated by mass ratio, ammonia water:pentaerythritol:3-aminopropyltrimethoxysilane:propylene oxide:ethylene oxide = (1 - 2):(1 - 2):(1 - 2):(40 - 60):100.

[0038] Further, in S451, the addition amount of isophorone diisocyanate is 25% - 35% of the mass of ethylene oxide.

[0039] Further, in S452, calculated by mass ratio, glycerol:dimethylolpropionic acid:xanthan gum:the prepolymer:inorganic filler = (4 - 6):(4 - 6):(6 - 8):(20 - 25):100.

[0040] The present invention also provides a self-leveling mortar, which is obtained by using the preparation method of any of the above technical solutions.

[0041] Beneficial effects

[0042] The present invention provides a method for preparing self-leveling mortar. In this preparation method, gypsum, cement, river sand, and inorganic filler are first mixed and stirred evenly to obtain a mixture. Then, a defoamer, a water reducer, a retarder, a stabilizer, and a flow aid are mixed and stirred evenly to obtain a composite additive. Finally, the composite additive is added to the mixture and mixed evenly to obtain the self-leveling mortar. This self-leveling mortar can be used in the scenario of fine leveling of concrete floors. It is characterized by relatively high compressive strength and is not prone to problems such as bleeding, delamination, and unevenness. The reason why the self-leveling mortar of the present invention has the above advantages is as follows: First, the inorganic filler used in the present invention includes silicon carbide ceramic powder. Silicon carbide ceramics have excellent mechanical properties, especially flexural strength and wear resistance, and their hardness is relatively high. Therefore, the compressive strength of the self-leveling mortar is improved by adding silicon carbide ceramic powder. Second, the inorganic filler of the present invention not only includes silicon carbide ceramic powder, but also uses montmorillonite to coat and modify the silicon carbide ceramic powder by a hydrothermal method. Montmorillonite has a layered structure composed of hydrated aluminosilicate. When it absorbs water, due to the presence of water molecules between its layers, it can expand, improving the hydrophilic property of the silicon carbide ceramic powder, as well as its dispersion uniformity and dispersion stability in the aqueous slurry. Thus, after the self-leveling mortar of the present invention is prepared by adding water, the inorganic filler in it is not easily agglomerated and settled at the bottom of the mortar, and the self-leveling mortar is not prone to problems such as bleeding, delamination, and unevenness. Detailed Embodiments

[0043] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following provides a detailed description of specific embodiments of the present invention.

[0044] Unless otherwise specified, the reagents and raw materials used in the present invention can be purchased through commercial channels. The experimental methods without specific conditions mentioned in the following embodiments are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0045] The embodiment of the present invention provides a method for preparing self-leveling mortar, and this preparation method includes:

[0046] S100. Mix and stir evenly gypsum, cement, river sand, and inorganic filler according to the mass ratio of gypsum:cement:river sand:inorganic filler = (55 - 60):(10 - 15):(10 - 15):(10 - 15) to obtain a mixture;

[0047] S200. Mix and stir evenly a defoamer, a water reducer, a retarder, a stabilizer, and a flow aid according to the mass ratio of defoamer:water reducer:retarder:stabilizer:flow aid = (1 - 2):(1.2 - 1.5):(0.4 - 0.5):(0.4 - 0.5) to obtain a composite additive;

[0048] S300. While the mixture is being stirred, add the composite additive to the mixture at a mass ratio of composite additive: mixture = (3 - 4.5): 100 in a uniform speed and keep stirring until the mixture and the composite additive are evenly mixed to obtain a self-leveling mortar.

[0049] In the above S100, the particle size of the river sand, as well as the stirring speed and stirring time for mixing and stirring the gypsum, cement, river sand, and inorganic filler can be selected and adjusted by those skilled in the art according to actual needs.

[0050] In the above S200, the defoamer includes at least one of the following or a combination thereof: Sago - 1667 defoamer, Sago - 1886 defoamer, Modaflow9200 defoamer.

[0051] In the above S200, the water - reducing agent includes at least one of the following or a combination thereof: sodium tripolyphosphate water - reducing agent, sodium ethylenediaminetetraacetate water - reducing agent, sodium iminotriacetate water - reducing agent.

[0052] In the above S200, the setting retarder includes at least one of the following or a combination thereof: sodium gluconate setting retarder, sodium ethylenediaminetetraacetate setting retarder, sodium tartrate setting retarder, sodium borate setting retarder, aluminum sulfate setting retarder.

[0053] In the above S200, the stabilizer includes at least one of the following or a combination thereof: polyvinyl alcohol stabilizer, guar gum stabilizer, sodium alginate stabilizer.

[0054] In the above S200, the flow - aid includes at least one of the following or a combination thereof: sodium stearate flow - aid, magnesium stearate flow - aid, potassium stearate flow - aid, talc powder flow - aid, magnesium silicate flow - aid.

[0055] Preferably, in the above S200, the defoamer is Sago - 1667 defoamer, the water - reducing agent is sodium iminotriacetate, the setting retarder is sodium tartrate setting retarder, the stabilizer is guar gum stabilizer, and the flow - aid is magnesium stearate flow - aid.

[0056] In the above S300, the stirring speed and stirring time can be selected and adjusted by those skilled in the art according to actual needs.

[0057] Through the above S100 - S300, a self - leveling mortar applicable to the fine leveling scenario of a concrete floor can be prepared. To improve the compressive strength of this self - leveling mortar, the present invention adds an inorganic filler to the raw materials. This inorganic filler mainly includes silicon carbide ceramic powder with excellent flexural strength and wear resistance.

[0058] It should be noted that silicon carbide ceramic powder has a large specific surface area, high surface energy, and poor hydrophilicity. Therefore, it is prone to agglomeration and sedimentation in aqueous slurries. This problem may cause the self-leveling mortar to be prone to bleeding, delamination, and unevenness.

[0059] To solve this problem, the present invention uses montmorillonite to coat and modify silicon carbide ceramic powder by hydrothermal method, thereby improving the hydrophilicity of silicon carbide ceramic powder, as well as its dispersion uniformity and dispersion stability in aqueous slurries, and further solving the problems of bleeding, delamination, and unevenness that are prone to occur in self-leveling mortar.

[0060] Specifically, the inorganic filler of the present invention is prepared by the following steps:

[0061] S410: Mix silicon carbide powder, aluminum hydroxide powder, chitosan, yttrium oxide, titanium carbide, and sodium hexametaphosphate evenly in ethanol to obtain a slurry;

[0062] S420: Grind the slurry evenly by wet grinding. After grinding, take out the slurry for filtration, washing, and drying to obtain a powder;

[0063] S430: Calcinate the powder. After the calcination is completed, cool it with the furnace and grind it to obtain silicon carbide ceramic powder;

[0064] S440: Use raw materials including silicon carbide ceramic powder and montmorillonite to prepare an inorganic filler by hydrothermal method.

[0065] Preferably, in S410, calculated by mass ratio, silicon carbide powder:aluminum hydroxide powder:chitosan:yttrium oxide:titanium carbide:sodium hexametaphosphate:ethanol = (40 - 45):(5 - 10):(4 - 6):(1 - 2):(0.5 - 1):(0.5 - 1):100.

[0066] Preferably, in S420, the process parameters of wet grinding include: using zirconia balls as the grinding medium and grinding at a speed of 350 rpm - 400 rpm for 20 min - 30 min.

[0067] Preferably, in S430, the process parameters of calcination include: calcining at a temperature of 2150 °C - 2250 °C for 1 h - 2 h.

[0068] The reason for the present invention to prepare the inorganic filler through the above S410 - S440 is as follows.

[0069] First, one of the reasons for the easy sedimentation of inorganic fillers in the prior art is their high density. Therefore, when preparing silicon carbide ceramic powder in the present invention, chitosan is added to the raw materials as a pore-forming agent. Chitosan decomposes when heated during high-temperature calcination, providing the porosity of silicon carbide ceramic powder and reducing its density.

[0070] Secondly, the silicon carbide in the prior art specifically includes silicon carbide with two structures of 4H-SiC and 6H-SiC. Among them, the unit cell of 4H-SiC contains 4 silicon atoms and 4 carbon atoms. Each silicon atom and carbon atom are completely covalently bonded, and a hexagonal unit cell is formed. 4 silicon atoms and 4 carbon atoms form a hexagonal ring, and adjacent hexagonal rings are connected by edges to form a complete unit cell. The above structure makes 4H-SiC have higher compressive strength than 6H-SiC. Correspondingly, the present invention introduces yttrium oxide as the first dopant, uses yttrium oxide to artificially create defects in the crystal phase structure of the ceramic, breaks the growth rule of 6H-SiC, and induces the generation and growth of 4H-SiC crystal nuclei, thereby forming a silicon carbide ceramic with a higher content of 4H-SiC to improve its compressive strength. On this basis, the present invention introduces titanium carbide as the second dopant, and uses the characteristic that the radius of titanium atoms is relatively large to cause lattice distortion of 4H-SiC grains and limit the excessive growth of 4H-SiC grains. Thus, yttrium oxide and titanium carbide with a specific ratio and mutual cooperation help to improve the mechanical properties of the silicon carbide ceramic, especially the compressive strength.

[0071] In addition, sodium hexametaphosphate is used as a dispersant to improve the dispersion uniformity of silicon carbide powder and aluminum hydroxide powder in ethanol, and thus ensure the effect of wet grinding.

[0072] Preferably, S440 includes:

[0073] S441. Mix tetrabutyl titanate, montmorillonite, polyvinylpyrrolidone and acetylacetone evenly in water, gradually add ethanol with a mass twice that of water drop by drop while stirring synchronously, and let it stand for 0.5 h - 1 h after dropping to obtain a sol mixture;

[0074] S442. Mix the sol mixture and silicon carbide ceramic powder evenly and feed them into a reaction kettle. After adjusting the pH value to 9 - 10 by adding alkali, carry out hydrothermal reaction under heating and pressure. After the reaction is completed, relieve the temperature and pressure, extract the solid matter, filter and dry it to obtain a precursor;

[0075] S443. Calcinate the precursor, cool it with the furnace after the calcination is completed, grind and crush it to obtain an inorganic filler.

[0076] Preferably, in S441, the particle size of montmorillonite is 10 nm - 100 nm.

[0077] Preferably, in S442, the particle size of the silicon carbide ceramic powder is 50 μm - 200 μm.

[0078] Preferably, in S441, by mass ratio, tetrabutyl titanate: montmorillonite: polyvinylpyrrolidone: acetylacetone: water = (10 - 15):(20 - 30):(6 - 8):(8 - 10):100.

[0079] Preferably, in S442, by mass ratio, the sol mixture: silicon carbide ceramic powder = (20 - 30):100.

[0080] Preferably, in S442, the process parameters of the hydrothermal reaction include: carrying out a hydrothermal reaction for 2 h - 2.5 h under the temperature condition of 140°C - 160°C and the pressure condition of 5 MPa - 7 MPa.

[0081] Preferably, in S443, the process parameters of the calcination include: calcining for 1 h - 2 h under the temperature condition of 450°C - 550°C.

[0082] The reason for the present invention to use montmorillonite to coat and modify silicon carbide ceramic powder by hydrothermal method through the above S441 - S443 is as follows. The present invention first utilizes the characteristic that tetrabutyl titanate can hydrolyze in a water and ethanol system, mixes tetrabutyl titanate, montmorillonite, polyvinylpyrrolidone and acetylacetone evenly in water, gradually drops ethanol with a mass twice that of water and stirs synchronously, thereby preparing a sol mixture with montmorillonite evenly dispersed. Furthermore, the present invention mixes the sol mixture and silicon carbide ceramic powder, and carries out a hydrothermal reaction by heating and pressurizing. The nano - level montmorillonite evenly dispersed in the sol mixture deposits and coats on the surface of the silicon carbide ceramic powder under an alkaline environment. Through calcination, silicon carbide ceramic powder coated with montmorillonite can be obtained. Montmorillonite has a layered structure composed of hydrous aluminum silicate. When absorbing water, the montmorillonite on the surface of the silicon carbide ceramic powder utilizes the characteristic that there are water molecules between layers to absorb water and expand, improving the volume and hydrophilic property of the silicon carbide ceramic powder, as well as the dispersion uniformity and dispersion stability degree of the silicon carbide ceramic powder in the aqueous slurry. Therefore, the above steps use montmorillonite to coat and modify silicon carbide ceramic powder by hydrothermal method, thereby improving the dispersion stability of the silicon carbide ceramic powder.

[0083] Preferably, after S440, the preparation method of the inorganic filler further includes:

[0084] S450. Modifying the inorganic filler with a hydrophilic polyether polymer material.

[0085] Among them, S450 specifically includes:

[0086] S451. Under nitrogen protection, add ammonia water, pentaerythritol, and 3-aminopropyltrimethoxysilane into a reaction kettle and mix them evenly. Heat the reaction kettle to 55°C - 60°C, then add propylene oxide and ethylene oxide. React for 0.5 h - 1 h under a vacuum pressure condition and a temperature condition of 100°C - 105°C. After the reaction ends, cool the reaction kettle to 80°C - 90°C and adjust it to neutral with acid. Subsequently, add isophorone diisocyanate to the reaction kettle and continue the heat preservation reaction for 1 h - 1.5 h. After the reaction ends, cool it to obtain a prepolymer.

[0087] S452. Mix glycerol, dimethylolpropionic acid, xanthan gum, the prepolymer, and inorganic filler in a reaction kettle and react for 2 h - 2.5 h under a temperature condition of 90°C - 95°C. After the reaction ends, extract the solid matter and dry it to obtain the modified inorganic filler.

[0088] Preferably, in S451, calculated by mass ratio, ammonia water:pentaerythritol:3-aminopropyltrimethoxysilane:propylene oxide:ethylene oxide = (1 - 2):(1 - 2):(1 - 2):(40 - 60):100.

[0089] Preferably, in S451, the addition amount of isophorone diisocyanate is 25% - 35% of the mass of ethylene oxide.

[0090] Preferably, in S452, calculated by mass ratio, glycerol:dimethylolpropionic acid:xanthan gum:prepolymer:inorganic filler = (4 - 6):(4 - 6):(6 - 8):(20 - 25):100.

[0091] In the above S451, propylene oxide and ethylene oxide react to obtain a hydrophilic polyether with silane oxy groups at both ends under the action of the catalyst ammonia water and the initiator pentaerythritol. This hydrophilic polyether continues to react with isophorone diisocyanate to obtain a polyether-based polyurethane resin prepolymer with excellent water absorption performance. In S452, this polyether-based polyurethane resin prepolymer undergoes a polymerization reaction under the action of the chain extender glycerol and dimethylolpropionic acid to form a polyether polymer material film layer on the surface of the inorganic filler. This polyether polymer material film layer can absorb water and swell, thereby further improving the dispersion stability of the silicon carbide ceramic powder.

[0092] Example 1

[0093] This example provides a preparation method of an inorganic filler, which includes the following steps:

[0094] S1. Mix silicon carbide powder, aluminum hydroxide powder, chitosan, yttrium oxide, titanium carbide, sodium hexametaphosphate in ethanol according to the mass ratio of silicon carbide powder: aluminum hydroxide powder: chitosan: yttrium oxide: titanium carbide: sodium hexametaphosphate: ethanol = 45:5:5:2:1:1:100 and stir evenly to obtain a slurry;

[0095] S2. Use a planetary ball mill, with zirconia balls as the grinding medium, wet grind the slurry at a speed of 350 rpm for 30 min. After grinding, take out the slurry for filtration, wash it twice with water, and infrared dry it at 90 °C to obtain a powder;

[0096] S3. Calcinate the powder at a temperature of 2200 °C for 2 h. After the calcination is completed, cool it with the furnace, grind and crush it to obtain silicon carbide ceramic powder;

[0097] S4. Mix tetrabutyl titanate, montmorillonite, polyvinylpyrrolidone, and acetylacetone in water according to the mass ratio of tetrabutyl titanate: montmorillonite: polyvinylpyrrolidone: acetylacetone: water = 10:25:6:6:100, and gradually add ethanol with a mass twice that of water while stirring synchronously. After the addition is completed, let it stand for 1 h to obtain a sol mixture;

[0098] S5. Mix the sol mixture and silicon carbide ceramic powder evenly according to the mass ratio of sol mixture: silicon carbide ceramic powder = 25:100 and feed them into a reaction kettle. After adjusting the pH value to 10 with alkali, carry out a hydrothermal reaction at a temperature of 140 °C and a pressure of 5 MPa for 2.5 h. After the reaction is completed, release the temperature and pressure, extract the solid matter for filtration and infrared drying to obtain a precursor;

[0099] S6. Calcinate the precursor at a temperature of 500 °C for 2 h. After the calcination is completed, cool it with the furnace, grind and crush it to obtain an inorganic filler;

[0100] S7. Under nitrogen protection, add ammonia water, pentaerythritol, and 3-aminopropyltrimethoxysilane to a reaction kettle and mix them evenly according to the mass ratio of ammonia water: pentaerythritol: 3-aminopropyltrimethoxysilane: propylene oxide: ethylene oxide = 1:1:2:40:100. After heating the reaction kettle to 60 °C, add propylene oxide and ethylene oxide. React at a pressure of vacuum and a temperature of 105 °C for 1 h. After the reaction is completed, cool the reaction kettle to 90 °C and adjust it to neutral with acid. Then add isophorone diisocyanate to the reaction kettle. The addition amount of isophorone diisocyanate is 30% of the mass of ethylene oxide, and continue to keep warm and react for 1.5 h. After the reaction is completed, cool it to obtain a prepolymer;

[0101] S8. Mix glycerol, dimethylolpropionic acid, xanthan gum, prepolymer, and inorganic filler in a reaction kettle according to the mass ratio of glycerol:dimethylolpropionic acid:xanthan gum:prepolymer:inorganic filler = 4:4:6:25:100, and react at 90 °C for 2.5 h. After the reaction, extract the solid matter and dry it to obtain the modified inorganic filler.

[0102] Example 2

[0103] This example provides a preparation method of inorganic filler, which includes the following steps:

[0104] S1. Mix silicon carbide powder, aluminum hydroxide powder, chitosan, yttrium oxide, titanium carbide, sodium hexametaphosphate in ethanol according to the mass ratio of silicon carbide powder:aluminum hydroxide powder:chitosan:yttrium oxide:titanium carbide:sodium hexametaphosphate:ethanol = 40:10:5:2:0.5:0.5:100, and stir evenly to obtain a slurry.

[0105] S2. Use a planetary ball mill with zirconia balls as the grinding medium, and wet-grind the slurry at a speed of 350 rpm for 30 min. After grinding, take out the slurry, filter it, wash it twice with water, and dry it by infrared at 90 °C to obtain a powder.

[0106] S3. Calcinate the powder at 2200 °C for 2 h, cool it in the furnace after calcination, and grind and crush it to obtain silicon carbide ceramic powder.

[0107] S4. Mix tetrabutyl titanate, montmorillonite, polyvinylpyrrolidone, and acetylacetone in water according to the mass ratio of tetrabutyl titanate:montmorillonite:polyvinylpyrrolidone:acetylacetone:water = 10:25:6:6:100, and mix evenly. Gradually add ethanol with a mass twice that of water and stir synchronously. After dropping, let it stand for 1 h to obtain a sol mixture.

[0108] S5. Mix the sol mixture and silicon carbide ceramic powder according to the mass ratio of sol mixture:silicon carbide ceramic powder = 25:100, mix evenly and feed it into a reaction kettle. After adjusting the pH value to 10 with alkali, carry out a hydrothermal reaction at 160 °C and 7 MPa for 2 h. After the reaction, release the temperature and pressure, extract the solid matter, filter it, and dry it by infrared to obtain a precursor.

[0109] S6. Calcinate the precursor at 500 °C for 2 h, cool it in the furnace after calcination, and grind and crush it to obtain inorganic filler.

[0110] S7. Under nitrogen protection, ammonia water, pentaerythritol, 3-aminopropyltrimethoxysilane, propylene oxide, and ethylene oxide were added to the reaction kettle and mixed evenly according to the mass ratio of ammonia water:pentaerythritol:3-aminopropyltrimethoxysilane:propylene oxide:ethylene oxide = 2:2:2:60:100. After the reaction kettle was heated to 60°C, propylene oxide and ethylene oxide were added. The reaction was carried out under a vacuum pressure condition and a temperature condition of 105°C for 1 h. After the reaction ended, the reaction kettle was cooled to 90°C and acid was added to adjust to neutrality. Subsequently, isophorone diisocyanate was added to the reaction kettle, and the addition amount of isophorone diisocyanate was 30% of the mass of ethylene oxide. The reaction was continued under heat preservation for 1.5 h. After the reaction ended, it was cooled to obtain a prepolymer;

[0111] S8. Glycerol, dimethylolpropionic acid, xanthan gum, prepolymer, and inorganic filler were mixed in the reaction kettle according to the mass ratio of glycerol:dimethylolpropionic acid:xanthan gum:prepolymer:inorganic filler = 4:4:6:25:100, and the reaction was carried out at a temperature of 90°C for 2.5 h. After the reaction ended, the solid was extracted and dried to obtain the modified inorganic filler.

[0112] Example 3

[0113] This example provides a preparation method of an inorganic filler, which includes the following steps:

[0114] S1. Silicon carbide powder, aluminum hydroxide powder, chitosan, yttrium oxide, titanium carbide, sodium hexametaphosphate, and ethanol were mixed and stirred evenly in ethanol according to the mass ratio of silicon carbide powder:aluminum hydroxide powder:chitosan:yttrium oxide:titanium carbide:sodium hexametaphosphate:ethanol = 40:10:5:2:0.5:0.5:100 to obtain a slurry;

[0115] S2. Using a planetary ball mill with zirconia balls as the grinding medium, the slurry was wet-ground at a speed of 350 rpm for 30 min. After grinding, the slurry was taken out for filtration, washed twice with water, and infrared dried at 90°C to obtain a powder;

[0116] S3. The powder was calcined at a temperature of 2200°C for 2 h. After the calcination ended, it was cooled with the furnace and ground and pulverized to obtain silicon carbide ceramic powder;

[0117] S4. Tetrabutyl titanate, montmorillonite, polyvinylpyrrolidone, acetylacetone, and water were mixed evenly in water according to the mass ratio of tetrabutyl titanate:montmorillonite:polyvinylpyrrolidone:acetylacetone:water = 10:25:6:6:100. Ethanol with twice the mass of water was gradually added dropwise while stirring synchronously. After the addition was completed, it was left standing for 1 h to obtain a sol mixture;

[0118] S5. Mix the sol mixture and silicon carbide ceramic powder evenly according to the mass ratio of sol mixture : silicon carbide ceramic powder = 25 : 100, and feed them into a reaction kettle. After adjusting the pH value to 10 by adding alkali, carry out a hydrothermal reaction at a temperature of 160 °C and a pressure of 7 MPa for 2 h. After the reaction, reduce the temperature and pressure, extract the solid matter, filter it, and dry it by infrared to obtain the precursor.

[0119] S6. Calcinate the precursor at a temperature of 500 °C for 2 h. After the calcination, cool it with the furnace, grind and crush it to obtain the inorganic filler.

[0120] Example 4

[0121] This example provides a preparation method of an inorganic filler, which includes the following steps:

[0122] S1. Mix silicon carbide powder, aluminum hydroxide powder, chitosan, sodium hexametaphosphate in ethanol evenly according to the mass ratio of silicon carbide powder : aluminum hydroxide powder : chitosan : sodium hexametaphosphate : ethanol = 40 : 10 : 5 : 2 : 100 to obtain a slurry.

[0123] S2. Use a planetary ball mill, with zirconia balls as the grinding medium, grind the slurry wet at a speed of 350 rpm for 30 min. After grinding, take out the slurry, filter it, wash it twice with water, and dry it by infrared at 90 °C to obtain a powder.

[0124] S3. Calcinate the powder at a temperature of 2200 °C for 2 h. After the calcination, cool it with the furnace, grind and crush it to obtain the inorganic filler of silicon carbide ceramic powder.

[0125] Example 5

[0126] This example provides a preparation method of a self-leveling mortar, which includes the following steps:

[0127] S1. Mix gypsum, cement, river sand, and inorganic filler evenly according to the mass ratio of gypsum : cement : river sand : inorganic filler = 55 : 15 : 15 : 15 to obtain a mixture.

[0128] S2. Mix Sago-1667 defoamer, sodium iminodiacetate, sodium tartrate, guar gum, and magnesium stearate evenly according to the mass ratio of Sago-1667 defoamer : sodium iminodiacetate : sodium tartrate : guar gum : magnesium stearate = 1 : 1.5 : 0.5 : 0.5 to obtain a composite additive.

[0129] S3. While stirring the mixture, add the composite additive to the mixture at a constant speed according to the mass ratio of composite additive : mixture = 3.5 : 100, and keep stirring until the mixture and the composite additive are mixed evenly to obtain the self-leveling mortar.

[0130] Among them, the inorganic filler used in S1 is obtained by preparation through the above-mentioned Example 1.

[0131] Example 6

[0132] This example provides a preparation method of self-leveling mortar. The preparation method is the same as that of Example 5, except that the inorganic filler used in S1 of Example 6 is obtained by preparation through the above-mentioned Example 2.

[0133] Example 7

[0134] This example provides a preparation method of self-leveling mortar. The preparation method is the same as that of Example 5, except that the inorganic filler used in S1 of Example 7 is obtained by preparation through the above-mentioned Example 3.

[0135] Example 8

[0136] This example provides a preparation method of self-leveling mortar. The preparation method is the same as that of Example 5, except that the inorganic filler used in S1 of Example 8 is obtained by preparation through the above-mentioned Example 4.

[0137] Performance test

[0138] The self-leveling mortar prepared in Examples 5-8 was mixed with water in the same proportion to form a paste, and cylindrical specimens with a diameter of 40 mm and a height of 100 mm were prepared. According to GB / T17671-2021, a compressive strength test was carried out on the top surface of the specimens using a compressive strength testing machine, and the load was uniformly applied at a rate of 2000 N / s until failure. The quotient obtained by dividing the maximum load (N) at failure by the compressive area (mm 2 ) was used as the compressive strength (MPa). Among them, the compressive strengths of the specimens prepared with the self-leveling mortar of Examples 5-8 were 103 MPa, 108 MPa, 107 MPa, and 90 MPa in sequence.

[0139] According to GB / T50080-2016, the bleeding rate B of the self-leveling mortar prepared in Examples 5-8 was tested. The bleeding rate B = 100×Vw / [(W / m T )×m]; where Vw is the total bleeding volume (mL), W is the mixing water consumption for the test (mL), m T is the total mass of the mixed material for the test (g), and m is the mass of the mixed material specimen for the test (g). Among them, the bleeding rates of the self-leveling mortar of Examples 5-8 were 0.28%, 0.30%, 0.56%, and 0.72% in sequence.

[0140] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A method for preparing a self-leveling mortar, characterized in that: The preparation method comprises: S100, mixing and stirring the gypsum, the cement, the river sand and the inorganic filler in a mass ratio of gypsum: cement: river sand: inorganic filler = (55-60): (10-15): (10-15): (10-15) to obtain a mixture; S200, mixing and stirring the defoamer, the water reducer, the retarder, the stabilizer and the flow aid in a mass ratio of defoamer: water reducer: retarder: stabilizer: flow aid = (1-2): (1.2-1.5): (0.4-0.5): (0.4-0.5) to obtain a composite additive; S300, while the mixture is being stirred, adding the composite additive to the mixture at a mass ratio of composite additive:mixture = (3-4.5):100 at a uniform speed and stirring until the mixture and the composite additive are evenly mixed to obtain the self-leveling mortar; Wherein, the preparation method of the inorganic filler comprises: S410, mixing and stirring silicon carbide powder, aluminum hydroxide powder, chitosan, yttrium oxide, titanium carbide and sodium hexametaphosphate in ethanol at a mass ratio of silicon carbide powder: aluminum hydroxide powder: chitosan: yttrium oxide: titanium carbide: sodium hexametaphosphate: ethanol = (40-45): (5-10): (4-6): (1-2): (0.5-1): (0.5-1): 100 to obtain a slurry; S420, wet-grinding the slurry uniformly, taking out the slurry after grinding, filtering, washing, and drying to obtain powder; S430, calcining the powder, cooling it in the furnace after calcination, grinding it, and obtaining silicon carbide ceramic powder; S440, using the raw materials including the silicon carbide ceramic powder and montmorillonite, to obtain the inorganic filler by a hydrothermal method; S440 includes: S441, tetra-n-butyl titanate, montmorillonite, polyvinyl pyrrolidone and acetylacetone are uniformly mixed in water, ethanol twice the mass of water is gradually added dropwise while stirring, and after the addition is completed, the mixture is allowed to stand for 0.5 h to 1 h to obtain a sol mixture; S442, mixing the sol mixture and the silicon carbide ceramic powder uniformly and feeding them into a reaction kettle, adding alkali to adjust the pH value to 9-10, heating and pressurizing for hydrothermal reaction, removing the temperature and pressure after the reaction is completed, extracting the solid, filtering and drying, and obtaining a precursor; S443, calcining the precursor, cooling it in the furnace after calcination, grinding it to obtain the inorganic filler; In S441, calculated by mass ratio, tetrabutyl titanate:montmorillonite:polyvinyl pyrrolidone:acetylacetone:water=(10-15):(20-30):(6-8):(8-10):100; In S442, calculated by mass ratio, sol mixture: silicon carbide ceramic powder = (20-30): 100; In S442, the process parameters of the hydrothermal reaction include: performing the hydrothermal reaction for 2 h to 2.5 h at a temperature of 140° C. to 160° C. and a pressure of 5 MPa to 7 MPa; In S443, the calcination process parameters include: calcination at a temperature of 450°C-550°C for 1h-2h.

2. The preparation method according to claim 1, characterized in that: In S420, the process parameters of the wet grinding include: using zirconium oxide balls as grinding media, grinding at a speed of 350 rpm-400 rpm for 20 min-30 min; and / or In S430, the calcination process parameters include: calcination at a temperature of 2150°C-2250°C for 1h-2h.

3. The preparation method according to any one of claims 1 to 2, characterized in that The defoamer comprises at least one of the following or a combination thereof: Sago-1667 defoamer, Sago-1886 defoamer, Modaflow9200 defoamer; and / or The water reducer comprises at least one of the following or a combination thereof: sodium tripolyphosphate water reducer, sodium ethylenediaminetetraacetate water reducer, sodium imine triacetate water reducer; and / or The retarder comprises at least one of the following or a combination thereof: sodium gluconate retarder, sodium ethylenediaminetetraacetate retarder, sodium tartrate retarder, sodium borate retarder, aluminum sulfate retarder; and / or The stabilizer comprises at least one of the following or a combination thereof: a polyvinyl alcohol stabilizer, a guar gum stabilizer, a sodium alginate stabilizer; and / or The glidant includes at least one of the following or a combination thereof: sodium stearate glidant, magnesium stearate glidant, potassium stearate glidant, talc glidant, and magnesium silicate glidant.

4. The preparation method according to any one of claims 1 to 2, characterized in that The defoamer is Sago-1667 defoamer, the water reducer is sodium imine triacetate, the retarder is sodium tartrate retarder, the stabilizer is guar gum stabilizer, and the flow aid is magnesium stearate flow aid.

5. The preparation method according to any one of claims 1 to 2, characterized in that: After S440, the method for preparing the inorganic filler further includes: S450, modifying the inorganic filler with a hydrophilic polyether polymer material.

6. The preparation method according to claim 5, characterized in that: S450 specifically includes: S451, under nitrogen protection, adding ammonia water, pentaerythritol and 3-aminopropyltrimethoxysilane into a reactor and mixing them evenly, heating the reactor to 55° C.-60° C., adding propylene oxide and ethylene oxide, reacting for 0.5 h-1 h under vacuum pressure conditions and temperature conditions of 100° C.-105° C., cooling the reactor to 80° C.-90° C. and adding acid to adjust to neutrality after the reaction, then adding isophorone diisocyanate into the reactor, continuing the heat preservation reaction for 1 h-1.5 h, cooling after the reaction, and obtaining a prepolymer; S452, mixing glycerol, dimethylol propionic acid, xanthan gum, prepolymer and inorganic filler in a reactor, and reacting at a temperature of 90°C-95°C for 2h-2.5h. After the reaction, extracting the solid and drying it to obtain the inorganic filler after the modification.

7. The preparation method according to claim 6, characterized in that: In S451, calculated by mass ratio, ammonia water: pentaerythritol: 3-aminopropyltrimethoxysilane: propylene oxide: ethylene oxide = (1-2): (1-2): (1-2): (40-60): 100; and / or In S451, the amount of isophorone diisocyanate added is 25%-35% of the mass of ethylene oxide; and / or In S452, calculated by mass ratio, glycerol: dimethylolpropionic acid: xanthan gum: prepolymer: inorganic filler = (4-6): (4-6): (6-8): (20-25):

100.

8. A self-leveling mortar, characterized in that: The self-leveling mortar is obtained by the preparation method according to any one of claims 1 to 7.