A composite agent with water-reducing and mud-inhibiting effects and a preparation method thereof

Abstract

The application provides a composite agent with water-reducing and mud-inhibiting effects and a preparation method thereof. The composite agent is prepared by the following steps: firstly, preparing a multi-branched "core" through esterification of a polyhydric alcohol and an organic acid; secondly, preparing a multi-branched polymer water-reducing component through polymerization between the multi-branched "core" and different components; and thirdly, mixing the water-reducing component with a mud-inhibiting component, keeping warm, and cooling to obtain the composite agent with water-reducing and mud-inhibiting effects. The composite agent increases the electrostatic repulsion of the cement particle surface, makes the cement particles more fully dispersed, improves the slump retention of the concrete, prolongs the setting time of the concrete, and has good water-reducing and retarding effects.

Description

Technical Field

[0001] This invention relates to a composite agent with water-reducing and mud-suppressing effects and its preparation method, belonging to the field of building materials technology. Background Technology

[0002] With the continuous development of the construction industry, the performance requirements for building materials are also constantly increasing. Admixtures are the most frequently used component in the preparation of high-performance concrete. Composite agents, which are substances added to improve and adjust the performance of concrete, have become one of the most indispensable components in the cement concrete field. Among cement composite agents, water-reducing agents are the most widely used. Their main function is to hinder or destroy the flocculation structure of cement particles through surface activity, complexation, electrostatic repulsion, or stereochemical repulsion, thereby significantly improving the workability and fluidity of concrete, achieving the effects of saving cement, reducing mixing water, and increasing concrete strength. However, the fluidity, slump, and water reduction rate of ready-mixed concrete formulated with existing water-reducing agents are significantly affected by ambient temperature, transportation distance, and cement type. Therefore, the excessive drop in slump of ready-mixed concrete with temperature or time has always been a major problem that hinders normal construction. Especially in the hot summer, after long-term and long-distance transportation, the slump loss of concrete in the later stage is serious, which can lead to the inability to unload, excessive pump pressure, or even pump blockage. This results in the waste of raw materials, affects the quality of concrete, and affects the normal construction of the project. In addition, the single water-reducing agent has a limited effect and its effect on improving the various properties of concrete is not ideal.

[0003] Therefore, it is of great significance to develop a composite admixture that can improve the performance of concrete. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a composite agent with water-reducing and sludge-suppressing effects, and its preparation method.

[0005] This invention is achieved through the following technical solution:

[0006] A method for preparing a composite agent with water-reducing and sludge-suppressing effects includes the following steps:

[0007] (1) Preparation of polyol esters

[0008] Add 20-70 parts of polyol, 100-110 parts of organic acid, and 1-5 parts of catalyst to 200-500 parts of organic solvent. Under nitrogen protection, heat to 100-150℃ and react for 6-12 hours with stirring. After cooling and filtering the reaction product to remove the catalyst, remove the unreacted acid under vacuum to obtain the polyol ester.

[0009] (2) Preparation of multi-branched polymer water-reducing components

[0010] Add 20-30 parts of the polyol ester from step (1) to an aqueous solution containing 80-95 parts of component A under stirring at 60-80℃. Then, add 7-13 parts of component B, 0.1-0.4 parts of initiator and 0.5-1 parts of component C dropwise to the system after mixing. React for 6-10 hours and adjust the pH of the solution to 6-7 to obtain a multi-branched polymer water-reducing component with a solid content of 40-60%.

[0011] (3) Preparation of mud-suppressing components

[0012] Disperse 5-8 parts of natural organic polymer in 80-100 parts of a weak acid solution with a volume fraction of 2-10%, and activate it by stirring for 1-3 hours at 40-70℃. Then, add 30-40 parts of an aqueous solution of a functional group reagent with a mass fraction of 10-30% dropwise to the system, heat to 70-80℃, react for 6-10 hours, adjust to neutral pH, dialyze, and freeze dry to obtain the sludge-suppressing component.

[0013] (4) Preparation of composite agent

[0014] Mix 30-40 parts of the multi-branched polymer water-reducing component in step (2) with 1-5 parts of the mud-suppressing component in step (3) evenly, keep warm at 30-50℃ for 5-10 hours, and cool to obtain a composite agent with water-reducing and mud-suppressing effects.

[0015] According to a preferred embodiment of the present invention, in step (1), the polyol is selected from one or more of pentaerythritol, pentaerythritol, glycerol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, mannitol, dipentaerythritol, sorbitol, tripentaerythritol, trimethylolpropane, and xylitol.

[0016] According to a preferred embodiment of the present invention, in step (1), the organic acid is selected from one or more of acrylic acid, succinic acid, fumaric acid, methacrylic acid, and itaconic acid.

[0017] According to a preferred embodiment of the present invention, in step (1), the catalyst is selected from one or more of silica gel powder, organic acid, inorganic acid, inorganic acid salt, and inorganic solid acid.

[0018] More preferably, the inorganic solid acid is one or a mixture of two or more of the following: Al2O3 powder, X-type molecular sieve, silicon dioxide, Y-type molecular sieve, ZSM-type molecular sieve, SAPO-type molecular sieve, γ-alumina, η-alumina, θ-alumina, ZSM-5 zeolite, and montmorillonite.

[0019] More preferably, the inorganic acid salt is selected from one or a mixture of two or more of sodium monophosphate, disodium phosphate, and sodium hypophosphite.

[0020] More preferably, the organic acid is selected from one or more of the following: p-toluenesulfonic acid, citric acid, glycolic acid, acetic acid, tartaric acid, malic acid, formic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, phytic acid, adipic acid, glycolic acid, acrylic acid, methacrylic acid, lactic acid, gluconic acid, maleic acid, benzoic acid, and salicylic acid.

[0021] More preferably, the inorganic acid is selected from one or more of sulfuric acid, phosphoric acid, hypochlorous acid, chloric acid, boric acid, carbonic acid, nitric acid, nitrous acid, and hydrochloric acid.

[0022] According to a preferred embodiment of the present invention, in step (1), the organic solvent is selected from one or a mixture of two or more of 1,2-hexanediol, glycerol, ethylene glycol, propylene glycol, 1,2-hexanediol, 1,2-propanetriol, 1,2-propanediol, diethylene glycol, 1,6-hexanediol, triethylene glycol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, and N-methyl-2-pyrrolidone.

[0023] According to a preferred embodiment of the present invention, in step (2), component A is selected from one or more of vinyltrimethoxysilane, methacryloxypropyltrimethoxysilane, vinyltriethoxysilane, and allyl methacrylate silicon polymers.

[0024] According to a preferred embodiment of the present invention, in step (2), component B is selected from polymeric monomers or mixtures of polymeric monomers or mixtures of monomers and polymeric macromonomers, wherein the polymeric monomers have at least one of the following acidic groups: acrylic acid, methacrylic acid, amino acid cyclic anhydride, maleic acid, fumaric acid, itaconic acid, citraconic acid, and at least one polymerizable C=C functional group of styrene or vinyl.

[0025] More preferably, the amino acid ring anhydride is L-aspartic acid-4-benzyl ester-N-carboxylic acid ring anhydride or L-glutamic acid-5-benzyl ester-N-carboxylic acid ring anhydride;

[0026] According to a preferred embodiment of the present invention, in step (2), the initiator is selected from one or more of cerium ammonium nitrate, ammonium persulfate, azobisisobutylammonium hydrochloride, potassium persulfate, and hydrogen peroxide.

[0027] According to a preferred embodiment of the present invention, in step (2), component C is one or a mixture of two or more of the following: anionic monomers containing sulfonate monomers, zwitterionic monomers with unsaturated double bonds, or cationic monomers.

[0028] More preferably, the sulfonate-containing monomer is selected from one or more of sodium styrene sulfonate, sodium methpropylene sulfonate, p-styrene sulfonic acid, methyl p-styrene sulfonic acid, sodium propylene sulfonate, and 2-acrylamide-2-methylpropylene sulfonic acid.

[0029] More preferably, the zwitterionic monomer with the unsaturated double bond is selected from one or more of the following: [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonylpropyl)ammonium hydroxide, carboxybetaine acrylamide, 2-[[2-(methacryloyloxy)ethyl]dimethylamino]acetate, 2-(methacryloyloxy)ethyl-2-(trimethylamino)ethyl phosphate, carboxybetaine methacrylamide, methacryloylethyl carboxylic acid betaine, sulfobetaine methacrylate, [2-(acryloyloxy)ethyl]dimethyl-(3-sulfonylpropyl)ammonium hydroxide, sulfobetaine acrylamide, 2-(acryloyloxy)ethyl-2-(trimethylamino)ethyl phosphate, carboxybetaine methacrylate, sulfobetaine methacrylamide, and 3-[[2-(methacryloyloxy)ethyl]dimethylammonium]propionate.

[0030] More preferably, the cationic monomer is an acryloyloxyethyl alkyl quaternary ammonium salt and / or an allyl alkyl quaternary ammonium salt.

[0031] More preferably, the acryloyloxyethyl alkyl quaternary ammonium salt is selected from acryloyloxyethyl trimethyl ammonium chloride, dimethyl diallyl ammonium chloride, methacryloyloxyethyl trimethyl ammonium chloride, acryloyloxyethyl trimethyl ammonium bromide, methacryloyloxyethyl trimethyl ammonium bromide, acryloyloxyethyl-dodecyl-dimethyl ammonium chloride, methacryloyloxyethyl-dodecyl-dimethyl ammonium chloride, methacryloyloxyethyl-dodecyl-dimethyl ammonium bromide, methacryloyloxyethyl-dodecyl-dimethyl ammonium bromide, acryloyloxyethyl-tetradecyl-dimethyl ammonium chloride, methacryloyloxyethyl-tetradecyl-dimethyl ammonium chloride, propylene... One or a mixture of two or more of the following: acryloyloxyethyl-tetradecyl-dimethylammonium bromide, methacryloyloxyethyl-tetradecyl-dimethylammonium bromide, acryloyloxyethyl-hexadecyl-dimethylammonium chloride, methacryloyloxyethyl-hexadecyl-dimethylammonium chloride, acryloyloxyethyl-hexadecyl-dimethylammonium bromide, acryloyloxyethyl-octadecyl-dimethylammonium chloride, methacryloyloxyethyl-octadecyl-dimethylammonium chloride, acryloyloxyethyl-octadecyl-dimethylammonium bromide, and methacryloyloxyethyl-octadecyl-dimethylammonium bromide.

[0032] According to a preferred embodiment of the present invention, in step (2), the pH adjuster for adjusting the pH of the solution is one or a mixture of two or more of sodium bicarbonate, sodium dihydrogen phosphate, sodium methoxide, sodium ethoxide, ethanolamine, diethanolamine, triethanolamine, triisopropanolamine, disodium hydrogen phosphate, and ethanolamine.

[0033] According to a preferred embodiment of the present invention, in step (3), the natural organic polymer includes one or more of the following: chitosan, carboxymethyl chitosan, silk fibroin, corn protein, alginate, chitosan hyaluronic acid, alginic acid, sodium alginate, ammonium alginate, calcium alginate, magnesium alginate, potassium alginate, propylene glycol alginate, and dextran.

[0034] According to a preferred embodiment of the present invention, in step (3), the weak acid solution is one of formic acid, glacial acetic acid, tartaric acid, and citric acid.

[0035] According to a preferred embodiment of the present invention, in step (3), the functional group reagent comprises a quaternary ammonium salt containing an alkyl chain.

[0036] According to a preferred embodiment of the present invention, in step (3), the functional group reagent further includes one of the following: polyquaternary ammonium halide, ammonium sulfate, ethyl palmitate hydroxyethyl methyl ammonium sulfate, (3-chloro-2-hydroxypropyl)trimethyl ammonium chloride, decyl dimethyl ammonium bromide, decyl dimethyl ammonium chloride, bis(dodecyl dimethyl) ethylene diammonium bromide, trimethyl octyl ammonium chloride, benzalkonium chloride, aminodimethyl benzyl ammonium chloride, dialkyl dimethyl ammonium chloride, benzalkonium bromide, aminodimethyl benzyl ammonium bromide, dialkyl dimethyl ammonium bromide, benzyl trimethyl ammonium chloride, trioctyl methyl ammonium chloride, dodecyl dimethyl benzyl ammonium chloride, hexadecyl dimethyl benzyl ammonium chloride, hexadecyl trimethyl ammonium bromide, tetramethyl ammonium chloride, and 2,3-epoxypropyl-3-methyl ammonium chloride.

[0037] A composite agent with water-reducing and sludge-suppressing effects is prepared by the above method.

[0038] The above-mentioned composite agents with water-reducing and mud-suppressing effects are applied to concrete, and the amount of the composite agent added is 0.2-1 wt% of the concrete mass.

[0039] Technical features and advantages of the present invention:

[0040] 1. This invention first prepares a multi-branched "core" through the esterification reaction of polyols and organic acids. Then, through the polymerization of the multi-branched "core" with different components, a multi-branched polymer water-reducing component is prepared in two steps. Due to its special multi-arm structure, the steric hindrance effect is increased, and the affinity of the water-reducing component with the clay layer is significantly reduced, which greatly improves its clay tolerance.

[0041] 2. This invention utilizes cationic, zwitterionic, or anionic monomers as functional groups to participate in the polymerization reaction to prepare water-reducing agents. It works through electrostatic repulsion and steric hindrance: anionic groups such as carboxyl groups on the main chain are anchored and adsorbed onto the surface of cement particles, forming an electric double layer and generating electrostatic repulsion. Cationic, zwitterionic, and anionic groups in the side chains form hydrogen bonds with water molecules, giving the synthesized graft copolymer long branches and strong polar groups capable of generating steric hindrance. This forms a three-dimensional adsorption layer that extends into the cement paste, generating steric hindrance and enabling the dispersion of cement and other clinker particles in the paste. This achieves the requirements of water-reducing components with high water reduction and high slump retention, effectively reducing the sensitivity of the water-reducing component to clay and exhibiting excellent dispersion and dispersion retention.

[0042] 3. This invention uses silane containing C=C double bonds as a reactive monomer to synthesize a multi-branched polymer water-reducing component, resulting in a multi-branched polymer water-reducing component with silane side chains. This component can chemically bond with the surface of clay-based inorganic materials, avoiding intercalation and adsorption with clay. This significantly reduces the influence of clay on the performance of the water-reducing component and improves the working efficiency of the water-reducing agent in clay-containing environments.

[0043] 4. The siloxane groups introduced into the side chains of the polymer molecules of the water-reducing component in this invention can, on the one hand, react with Ca in cement-based materials. 2+ Bonding, on the other hand Ca 2+ It can be ionically crosslinked and bonded to -O-Si-O, which can significantly increase the degree of polymerization of the hydration product gel, thus helping to improve the early strength of cement materials.

[0044] 5. In this invention, natural organic polymers are chemically activated and quaternized, and carboxyl groups and quaternary ammonium salt groups with different charges are introduced into the molecular chains of natural organic polymers. Compared with small molecules such as alkyl quaternary ammonium salts, quaternized natural organic polymers can not only form multi-site binding with the negative charge centers on the surface of clay sheets through a large number of cationic groups on the molecular chain, but also make the clay hydrophobic, forming a protective layer on the clay surface to compress the interlayer spacing, inhibiting the side chain intercalation of water-reducing components in the clay, and reducing the adsorption of water-reducing components by clay through the preferential adsorption and solidification of clay by mud-suppressing components.

[0045] 6. The present invention is a composite agent with water-reducing and mud-suppressing effects. This composite agent increases the electrostatic repulsion on the surface of cement particles, making the cement particles more fully dispersed, improving the slump retention of concrete, and extending the setting time of concrete, thus having good water-reducing and retarding effects.

[0046] 7. This invention enhances the clay resistance of the composite agent by combining the clay-suppressing component and the multi-branched polymer water-reducing component. The addition of a clay curing agent allows the curing agent to adsorb clay preferentially before the water-reducing agent adsorbs it. By grafting and modifying the abundant hydroxyl, amino, and carboxyl groups on the natural polymer chain, it has better water solubility and clay adsorption, thereby inhibiting the absorption of the water-reducing component by the clay and giving full play to the water-reducing performance of the water-reducing component. This solves the problem of poor fluidity of cement-based slurry caused by the poor tolerance of the water-reducing component to clay. Attached Figure Description

[0047] Figure 1 The infrared spectrum of the multi-branched polymer water-reducing component prepared in Example 3 is shown.

[0048] Figure 2 The fluidity test results for each embodiment and comparative example are shown in the cement paste.

[0049] Figure 3 The results are slump test results for each embodiment and comparative example, when the material is incorporated into concrete.

[0050] Figure 4 The results show the water reduction rate test results of each embodiment and comparative example when incorporated into concrete.

[0051] Figure 5 The results are the compressive strength test results of Example 1 and Comparative Examples 1-2, which were incorporated into concrete in different proportions. Detailed Implementation

[0052] Other materials used in this invention, unless otherwise stated, are commercially available. Other terms used in this invention, unless otherwise specified, generally have the meanings commonly understood by those skilled in the art. The invention is further described in detail below with reference to specific embodiments and data. The following embodiments are merely illustrative and not intended to limit the scope of the invention in any way.

[0053] Example 1

[0054] A method for preparing a composite agent with water-reducing and sludge-suppressing effects, comprising the following steps:

[0055] (1) Preparation of polyol esters

[0056] 40 parts of pentaerythritol, 100 parts of acrylic acid, and 3 parts of toluenesulfonic acid were added to 300 parts of 1,2-hexanediol. Under nitrogen protection, the mixture was heated to 120°C and reacted for 8 hours with stirring. After cooling and filtering to remove toluenesulfonic acid from the reaction product, unreacted acid was removed under vacuum to obtain the polyol ester product.

[0057] (2) Preparation of multi-branched polymer water-reducing components

[0058] 20 parts of the polyol ester in step (1) were added to an aqueous solution containing 85 parts of vinyltrimethoxysilane under stirring at 60°C. Then, 8 parts of L-aspartic acid-4-benzyl ester-N-carboxycyclic anhydride, 0.2 parts of cerium ammonium nitrate and 0.6 parts of sodium styrene sulfonate were mixed and added dropwise to the vinyltrimethoxysilane aqueous solution. The reaction was continued for 6 hours. The pH of the solution was adjusted to 6 by sodium bicarbonate. Finally, a viscous multi-branched polymer water-reducing component with a solid content of 46% was obtained.

[0059] (3) Preparation of mud-suppressing components

[0060] Five parts of chitosan were dispersed in 80 parts of 4% glacial acetic acid solution and stirred at 50°C for 2 hours to activate it. Then, 30 parts of 10% trimethyloctylammonium chloride aqueous solution were added dropwise to the above mixture, heated to 75°C, and reacted for 8 hours. After that, the pH was adjusted to neutral, dialyzed, and freeze-dried to obtain the sludge-inhibiting component.

[0061] (4) Preparation of composite agent

[0062] The 30 parts of multi-branched polymer water-reducing component obtained in step (2) and the 2 parts of mud-suppressing component obtained in step (3) were mixed evenly, kept at 40°C for 6 hours, and cooled to obtain a composite agent with water-reducing and mud-suppressing effects.

[0063] Example 2

[0064] A method for preparing a composite agent with water-reducing and sludge-suppressing effects, comprising the following steps:

[0065] (1) Preparation of polyol esters

[0066] 50 parts of pentaerythritol, 105 parts of succinic acid, and 3 parts of Al2O3 powder were added to 400 parts of 1,2-propanediol. Under nitrogen protection, the mixture was heated to 130°C and reacted for 10 hours with stirring. After the reaction product was cooled and filtered to remove the Al2O3 powder, the unreacted acid was removed under vacuum to obtain the polyol ester product.

[0067] (2) Preparation of multi-branched polymer water-reducing components

[0068] 25 parts of the polyol ester from step (1) were added to an aqueous solution containing 80 parts of vinyltriethoxysilane under stirring at 70°C. Then, 10 parts of L-glutamic acid-5-benzyl ester-N-carboxycyclic anhydride, 0.3 parts of ammonium persulfate and 0.8 parts of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide were mixed and added dropwise to the vinyltriethoxysilane aqueous solution. The reaction was continued for 8 hours. The pH of the solution was adjusted to 6 by sodium bicarbonate. Finally, a viscous multi-branched polymer water-reducing component with a solid content of 51% was obtained.

[0069] (3) Preparation of mud-suppressing components

[0070] Six parts of carboxymethyl chitosan were dispersed in 90 parts of tartaric acid solution with a volume fraction of 6% and stirred at 50°C for 2 hours to activate it. Then, 35 parts of aminodimethylbenzylammonium chloride aqueous solution with a mass fraction of 20% were added dropwise to the above mixture, heated to 75°C, and reacted for 8 hours. After that, the pH was adjusted to neutral, dialyzed, and freeze-dried to obtain the sludge-suppressing component.

[0071] (4) Preparation of composite agent

[0072] The 35 parts of multi-branched polymer water-reducing component obtained in step (2) and the 3 parts of mud-suppressing component obtained in step (3) were mixed evenly, kept at 40°C for 6 hours, and cooled to obtain a composite agent with water-reducing and mud-suppressing effects.

[0073] Example 3

[0074] A method for preparing a composite agent with water-reducing and sludge-suppressing effects, comprising the following steps:

[0075] (1) Preparation of polyol esters

[0076] 60 parts of sorbitol, 110 parts of fumaric acid, and 3 parts of sodium hypophosphite were added to 500 parts of 2,3-butanediol. Under nitrogen protection, the mixture was heated to 140°C and reacted for 12 hours with stirring. After cooling and filtering the reaction product to remove sodium hypophosphite, the unreacted acid was removed under vacuum to obtain the polyol ester product.

[0077] (2) Preparation of multi-branched polymer water-reducing components

[0078] Add 30 parts of the polyol ester from step (1) to an aqueous solution containing 90 parts of methacryloyloxypropyltrimethoxysilane under stirring at 60-80℃. Then, mix 12 parts of L-aspartic acid-4-benzyl ester-N-carboxycyclic anhydride, 0.4 parts of potassium persulfate and 1 part of acryloyloxyethyltrimethylammonium chloride and add them dropwise to the aqueous solution of methacryloyloxypropyltrimethoxysilane. Continue the reaction for 10 hours. Adjust the pH of the solution to 7 with sodium bicarbonate to finally obtain a viscous multi-branched polymer water-reducing component with a solid content of 54%.

[0079] The infrared spectrum of the prepared multi-branched polymer water-reducing component is as follows: Figure 1 As shown in the figure, at 2884cm -1 The peak near the saturated CH bond stretching vibration is 3450 cm⁻¹. -1 The broad peak nearby represents the stretching vibration peak of the -OH group in the polyol ester. This peak is located at 1721 cm⁻¹ in the sample's infrared absorption spectrum. -1The stretching vibration peak of the carboxyl group (-C=O) was observed at 1620–1700 cm⁻¹. -1 The absence of carbon-carbon double bonds (-C=C-) indicates that both the carbon-carbon double bonds (-C=C-) of fumaric acid and silane participated in the polymerization reaction, suggesting complete monomer polymerization. At 2870 cm⁻¹ -1 The stretching vibration peak of the ether group (-COC-) can be found at 843 cm⁻¹. -1 The characteristic absorption peaks are located at the Si-C bond positions. The water-reducing components synthesized through different reaction steps contain functional groups such as ether groups (-COC-), carboxyl groups (-COO-), and Si-C bonds, indicating that multi-branched polymers have been successfully synthesized.

[0080] (3) Preparation of mud-suppressing components

[0081] Eight parts of shell hyaluronic acid were dispersed in 100 parts of 8% citric acid solution and stirred at 50°C for 2 hours to activate it. Then, 40 parts of 30% dialkyldimethylammonium bromide aqueous solution were added dropwise to the above mixture, heated to 75°C, and reacted for 8 hours. After that, the pH was adjusted to neutral, dialyzed, and freeze-dried to obtain the sludge-inhibiting component.

[0082] (4) Preparation of composite agent

[0083] The 40 parts of multi-branched polymer water-reducing component obtained in step (2) and the 4 parts of mud-suppressing component obtained in step (3) were mixed evenly, kept at 40°C for 6 hours, and cooled to obtain a composite agent with water-reducing and mud-suppressing effects.

[0084] Comparative Example 1

[0085] Using a multi-branched polymer water-reducing component as Comparative Example 1, i.e., Comparative Example 1 is carried out according to the method of Example 1, except that steps (3) and (4) are not prepared, and steps (1) and (2) are consistent with the preparation process of Example 1.

[0086] The preparation steps are as follows:

[0087] (1) Preparation of polyol esters

[0088] 40 parts of pentaerythritol, 100 parts of acrylic acid, and 3 parts of toluenesulfonic acid were added to 300 parts of 1,2-hexanediol. Under nitrogen protection, the mixture was heated to 120°C and reacted for 8 hours with stirring. After cooling and filtering the product to remove toluenesulfonic acid, the unreacted acid was removed under vacuum to obtain the polyol ester product.

[0089] (2) Preparation of multi-branched polymer water-reducing components

[0090] 20 parts of the polyol ester from step (1) were added to an aqueous solution containing 85 parts of vinyltrimethoxysilane under stirring at 60°C. Then, 8 parts of L-aspartic acid-4-benzyl ester-N-carboxycyclic anhydride, 0.2 parts of cerium ammonium nitrate, and 0.6 parts of sodium styrene sulfonate were mixed and added dropwise to the vinyltrimethoxysilane aqueous solution. The reaction was continued for 6 hours. The pH of the solution was adjusted to 6 by sodium bicarbonate. Finally, a viscous multi-branched polymer water-reducing component with a solid content of 46% was obtained.

[0091] Comparative Example 2

[0092] The 256 water-reducing agent sold by Shandong Xinhongyue Chemical Technology Co., Ltd. was used as Comparative Example 2.

[0093] Experimental Performance Testing

[0094] 1. Flowability

[0095] Figure 2 The fluidity test results of each embodiment and comparative example incorporated into cement paste are presented.

[0096] Each example and comparative example was added to cement paste at a rate of 0.2% of the cement mass, with a water-cement ratio of 0.29. The fluidity of the cement paste was tested according to the national standard GB / T 8077-2000 "Test Method for Homogeneity of Composite Agents". The test results are as follows. Figure 1As shown, in the initial stage, i.e., the first 30 minutes, the fluidity of the cement pastes from the examples and the comparative examples was not significantly different. This may be because, in the initial stage of cement hydration, there are more water-reducing agent molecules in the cement paste, resulting in a higher additive concentration. Both the examples and the comparative examples exhibited good dispersibility. After 60 minutes, the loss of the cement paste with the comparative example added was significantly higher than that of the cement pastes with the three examples as admixtures. At 2 hours, the fluidities of Examples 1-3 and Comparative Examples 1-2 were 265, 262, 266, 205, and 195, respectively, with loss rates of 8.93%, 9.02%, 8.27%, 16.32%, and 18.75% compared to the initial stage. This indicates that the three composite agents synthesized in Examples 1-3 have better dispersibility for cement than those in Comparative Examples 1-2. One reason is that the functional monomers introduced in the experiment contain cationic, anionic, or zwitterionic groups as functional groups to participate in the polymerization reaction to prepare water-reducing components. They function through electrostatic repulsion and steric hindrance: the anionic groups such as carboxyl groups on the main chain are anchored and adsorbed on the surface of cement particles to form an electric double layer, generating electrostatic repulsion; the cationic, zwitterionic, and anionic groups in the side chains form hydrogen bonds with water molecules, giving the synthesized graft copolymer long branches and strong polar groups that can generate steric hindrance, thereby forming a three-dimensional adsorption layer that extends into the cement paste and generates pores. The steric hindrance effect enables cement and other clinker particles to be uniformly dispersed in the slurry. On the other hand, the introduction of the mud-suppressing component in the composite agent further enhances the clay resistance of the water-reducing component. The addition of the mud-suppressing component can preferentially adsorb clay by the curing agent before the water-reducing component adsorbs clay. By grafting and modifying the abundant hydroxyl, amino, and carboxyl groups on the natural polymer chain, it has better water solubility and clay adsorption, thereby inhibiting the absorption of the water-reducing component by the clay, improving the tolerance of the water-reducing component to clay, and ultimately improving the fluidity of the cement slurry.

[0097] 2. Slump

[0098] Figure 3 The slump test results of each embodiment and comparative example incorporated into concrete are shown.

[0099] The concrete was added to each of the embodiments and comparative examples at a rate of 0.4% of the cement mass. The mass ratio of cement, sand, and aggregate was 320:720:1100. The slump of the concrete was tested according to the national standard GB / T50080-2016. The initial slump, 1-hour slump, and 2-hour slump were tested, and the results are as follows. Figure 3 As shown, the initial slump, 1-hour slump, and 2-hour slump of each embodiment are very close and all superior to those of the comparative example. Compared to the comparative example, each embodiment incorporates a clay solidifier component, whose unique multi-arm structure increases the steric hindrance effect, reduces the affinity of the polymer for the clay layer, and exhibits high slump retention and good dispersion retention.

[0100] 3. Water reduction rate

[0101] Figure 4 The water reduction rate test results of each embodiment and comparative example incorporated into concrete are presented.

[0102] Each example and comparative example was added to concrete at a rate of 0.4% of the cement mass. The mass ratio of cement, sand, and aggregate was 320:720:1100. The water ratio was controlled to maintain a slump of 210±10 mm. The water reduction rate was tested according to the national standard GB 8076-2008 "Concrete Admixtures". Water reduction rate W R (%) is obtained from the following formula:

[0103] W R = (W0-W1) / W0×100%

[0104] In the formula, W0: water consumption of blank concrete without additives, g; W1: water consumption of concrete with additives, g.

[0105] Water reduction rate results are as follows Figure 4 As shown in the figure, the water reduction rates of the concrete after incorporation in each embodiment are not significantly different. However, compared to Comparative Examples 1 and 2, which did not contain the clay-suppressing component, the water reduction rates of each embodiment are higher than those of the comparative examples. This demonstrates that the water-reducing components prepared in the embodiments, through the molecular structure design of the clay-suppressing component and the multi-branched polymer water-reducing component, further enhance the anti-clay ability of the water-reducing component, inhibit the absorption of the water-reducing component by clay, and fully utilize the water-reducing performance of the component, exhibiting excellent performance in terms of significant water reduction.

[0106] 4. Compressive strength

[0107] Figure 5 The compressive strength test results of Examples 1 and Comparative Examples 1-2, which were incorporated into concrete in different proportions, are shown.

[0108] Examples 1 and Comparative Examples 1-2 were added to concrete at amounts of 0.1%, 0.2%, 0.3%, and 0.4% of the cement mass, respectively. The mass ratio of cement, sand, and aggregate was 320:720:1100, and the bentonite content was 0.4% of the sand mass. All specimens were cured in a curing chamber for 7 days. The compressive strength of the concrete was tested according to the national standard GB / T50107-2010 "Standard for Determination of Concrete Strength". The test results are as follows: Figure 5As shown, after 7 days of curing, the compressive strength of concrete in Examples 1 and Comparative Examples 1-2 increased with increasing dosage after incorporation. However, regardless of the dosage, the compressive strength of concrete incorporating Example 1 was significantly higher than that of the comparative examples. In Example 1, even with a dosage of 0.3-0.4%, the compressive strength did not increase significantly. This is mainly due to the reduction of free water within the concrete and the dispersing effect of the water-reducing component on cement particles, which reduces the pore structure within the concrete, resulting in a denser concrete specimen structure and thus improved strength. Furthermore, the multi-branched water-reducing polymer has more adsorption sites on cement particles, leading to stronger dispersion between cement particles, more complete hydration reaction, and significantly improved strength. Secondly, the siloxane groups introduced into the side chains of the polymer molecules interact with the Ca in the cement material... 2+ Bonding, and Ca 2+ Through ionic crosslinking and -O-Si-O bonding, the degree of polymerization of the hydration product gel can be increased, thereby enhancing the strength of cement concrete. In summary, the composite agent with water-reducing and mud-suppressing effects has a certain inhibitory effect on the water absorption and swelling of clay, while reducing the adsorption of water by clay to concrete, thus effectively improving its mechanical properties.

[0109] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the disclosed technical content to create equivalent embodiments. However, any modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a composite agent with water-reducing and sludge-suppressing effects, comprising the following steps: (1) Preparation of polyol esters 40 parts of pentaerythritol, 100 parts of acrylic acid, and 3 parts of toluenesulfonic acid were added to 300 parts of 1,2-hexanediol. Under nitrogen protection, the mixture was heated to 120°C and reacted for 8 hours with stirring. After cooling and filtering to remove toluenesulfonic acid from the reaction product, unreacted acid was removed under vacuum to obtain the polyol ester product. (2) Preparation of multi-branched polymer water-reducing components 20 parts of the polyol ester in step (1) were added to an aqueous solution containing 85 parts of vinyltrimethoxysilane under stirring at 60°C. Then, 8 parts of L-aspartic acid-4-benzyl ester-N-carboxycyclic anhydride, 0.2 parts of cerium ammonium nitrate and 0.6 parts of sodium styrene sulfonate were mixed and added dropwise to the vinyltrimethoxysilane aqueous solution. The reaction was continued for 6 hours. The pH of the solution was adjusted to 6 by sodium bicarbonate. Finally, a viscous multi-branched polymer water-reducing component with a solid content of 46% was obtained. (3) Preparation of mud-suppressing components Five parts of chitosan were dispersed in 80 parts of 4% glacial acetic acid solution and stirred at 50°C for 2 hours to activate it. Then, 30 parts of 10% trimethyloctylammonium chloride aqueous solution were added dropwise to the mixture, heated to 75°C, and reacted for 8 hours. After that, the pH was adjusted to neutral, dialyzed, and freeze-dried to obtain the sludge-inhibiting component. (4) Preparation of composite agent The 30 parts of multi-branched polymer water-reducing component obtained in step (2) and the 2 parts of mud-suppressing component obtained in step (3) were mixed evenly, kept at 40°C for 6 hours, and cooled to obtain a composite agent with water-reducing and mud-suppressing effects.

2. A method for preparing a composite agent with water-reducing and sludge-suppressing effects, comprising the following steps: (1) Preparation of polyol esters 60 parts of sorbitol, 110 parts of fumaric acid, and 3 parts of sodium hypophosphite were added to 500 parts of 2,3-butanediol. Under nitrogen protection, the mixture was heated to 140°C and reacted for 12 hours with stirring. After cooling and filtering the reaction product to remove sodium hypophosphite, the unreacted acid was removed under vacuum to obtain the polyol ester product. (2) Preparation of multi-branched polymer water-reducing components Add 30 parts of the polyol ester from step (1) to an aqueous solution containing 90 parts of methacryloyloxypropyltrimethoxysilane under stirring at 60-80℃. Then, mix 12 parts of L-aspartic acid-4-benzyl ester-N-carboxycyclic anhydride, 0.4 parts of potassium persulfate and 1 part of acryloyloxyethyltrimethylammonium chloride and add them dropwise to the aqueous solution of methacryloyloxypropyltrimethoxysilane. Continue the reaction for 10 hours. Adjust the pH of the solution to 7 with sodium bicarbonate to finally obtain a viscous multi-branched polymer water-reducing component with a solid content of 54%. (3) Preparation of mud-suppressing components Eight parts of shell hyaluronic acid were dispersed in 100 parts of 8% citric acid solution and stirred at 50°C for 2 hours to activate it. Then, 40 parts of 30% dialkyldimethylammonium bromide aqueous solution were added dropwise to the mixture, heated to 75°C, and reacted for 8 hours. After that, the pH was adjusted to neutral, dialyzed, and lyophilized to obtain the sludge-inhibiting component. (4) Preparation of composite agent The 40 parts of multi-branched polymer water-reducing component obtained in step (2) and the 4 parts of mud-suppressing component obtained in step (3) were mixed evenly, kept at 40°C for 6 hours, and cooled to obtain a composite agent with water-reducing and mud-suppressing effects.

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