Preparation method and application of high-strength concrete viscosity-reducing polycarboxylate water reducer
Patent Information
- Application Number
- CN202611058218.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-16
- Publication Date
- 2026-09-01
AI Technical Summary
但在高强混凝土低水胶比体系中，传统聚羧酸减水剂存在明显局限性：一方面，水泥颗粒表面吸附的减水剂分子形成较厚的溶剂化水膜，消耗大量自由水；另一方面，孔隙液中未被吸附的减水剂分子会增大液相粘度，双重作用下反而加剧了混凝土浆体的粘稠化现象，难以同时满足高减水与低粘度的双重需求
[0021]This invention discloses a method for preparing a high-strength concrete viscosity-reducing polycarboxylate superplasticizer. The method uses double-bonded chitosan, macromonomers, small monomers, and double-bonded polyethyleneimine as copolymer components. The double-bonded chitosan and polyethyleneimine possess numerous active sites such as amino and hydroxyl groups, which can synergistically interact with the carboxyl groups of acrylic acid, effectively improving the adsorption and binding effect on inorganic particles. Simultaneously, their multiple double bonds impart a network-like, three-dimensional branched structure to the polymer, enhancing steric hindrance and improving dispersion in conjunction with the long chains of polyoxyethylene ether. Furthermore, the three-dimensional barrier structure of the superplasticizer, combined with the water released by the hydrophobic alkyl groups reducing the overall hydration level, better exerts its lubricating function and reduces particle adhesion. Therefore, the polycarboxylate superplasticizer of this invention achieves a high water reduction rate at low dosages, meeting the requirements for low water-cement ratio formulations in high-strength concrete. In addition, the preparation method of this invention is simple, the reaction conditions are mild, and it does not contain components that may corrode steel reinforcement or concrete, which is of great significance to the development of concrete admixtures.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of concrete admixtures, and in particular to a method for preparing and applying a high-strength concrete viscosity-reducing polycarboxylate superplasticizer. Background Technology
[0002] With the development of modern construction engineering towards high-rise, large-span, and high-durability directions, high-strength concrete, with its excellent mechanical properties, high durability, and lightweight structural advantages, is increasingly widely used in high-rise building core tubes, long-span bridges, pipe pile engineering, marine engineering, and ultra-high performance concrete components. To achieve high-strength design goals, high-strength concrete typically employs a mix design scheme with a low water-cement ratio and a high amount of cementitious materials, and often incorporates admixtures such as silica fume and ultrafine mineral powder with large specific surface area to optimize matrix density. However, the combination of a low water-cement ratio and a high amount of cementitious materials leads to a decrease in particle spacing, an increase in interparticle frictional resistance, and a reduction in free water content in the fresh concrete paste. This ultimately results in construction problems such as high paste viscosity, high pumping resistance, slow flow rate, and poor workability, severely restricting the engineering application and promotion of high-strength concrete.
[0003] Polycarboxylate superplasticizers, as the third generation of high-performance superplasticizers, have become core admixtures for improving the workability of concrete due to their outstanding advantages such as high water reduction rate, low dosage, and strong designability of molecular structure. Traditional polycarboxylate superplasticizers adsorb onto the surface of cement particles through anionic groups such as carboxyl groups, relying on the steric hindrance effect generated by the long polyether side chains to achieve dispersion and water reduction of cement particles. However, in high-strength concrete systems with low water-cement ratios, traditional polycarboxylate superplasticizers have obvious limitations: on the one hand, the superplasticizer molecules adsorbed on the surface of cement particles form a thick solvated water film, consuming a large amount of free water; on the other hand, the unadsorbed superplasticizer molecules in the pore fluid increase the viscosity of the liquid phase. Under these two effects, the thickening phenomenon of the concrete paste is exacerbated, making it difficult to simultaneously meet the dual requirements of high water reduction and low viscosity.
[0004] Currently, viscosity-reducing polycarboxylate superplasticizers have become a research hotspot in the field of concrete admixtures. Existing viscosity-reducing modifications are mainly divided into three technical routes: First, reducing the molecular weight or shortening the polyoxyethylene ether side chain, but this weakens the steric hindrance effect, leading to a decrease in water reduction rate and dispersion retention; Second, introducing hydrophobic functional groups into the molecular backbone to release free water, but the content of hydrophobic groups is limited, and excessive amounts can easily cause side effects such as excessive air entrainment and decreased strength, resulting in limited viscosity reduction; Third, physical compounding of multi-component mother liquor, but there are problems of competitive adsorption and poor performance stability, making it impossible to achieve synergistic optimization of viscosity reduction and water reduction at the molecular structure level, and it is difficult to simultaneously achieve the dual goals of increasing the thickness of the cement particle adsorption layer and reducing the content of residual superplasticizer in the pore liquid, resulting in significant shortcomings in overall performance. In recent years, the modification of natural polymers has become a new direction for the functionalization of polycarboxylate superplasticizers. Chitosan, as a natural cationic polysaccharide with both a rigid skeleton and multiple active sites, has been the subject of many existing modification studies, which focus on anti-mud, slump retention and early strength. However, it generally suffers from problems such as complex modification, low double bond grafting rate and poor copolymer compatibility. Moreover, there are few molecular structure designs specifically for the viscosity reduction needs of high-strength concrete, and its synergistic viscosity reduction potential has not yet been fully realized.
[0005] Therefore, it is necessary to provide a new technical solution to address the problems existing in the current technology. Summary of the Invention
[0006] To address the problems existing in the prior art, this invention provides a method for preparing and applying a high-strength concrete viscosity-reducing polycarboxylate superplasticizer. By combining different monomers and double-bonded chitosan and polyethyleneimine, and through the synergistic effect of the introduced branched structure and various groups such as amino and hydroxyl groups, multi-point anchoring is achieved. This method can balance high water reduction rate and excellent viscosity reduction effect, overcoming the defects existing in the prior art, and has good application prospects in concrete and other fields.
[0007] One object of the present invention is to provide a method for preparing a high-strength concrete viscosity-reducing polycarboxylate superplasticizer, the method comprising the following steps:
[0008] S1. Chitosan, catalyst and acrylic acid are mixed and heated to react, resulting in double-bonded chitosan;
[0009] S2. Mix the double-bonded chitosan, macromonomer, small-molecule monomer, double-bonded polyethyleneimine, chain transfer agent and initiator, and heat to react to obtain a high-strength concrete viscosity-reducing polycarboxylate superplasticizer.
[0010] The small molecule monomers include unsaturated carboxylic acid monomers and viscosity-reducing monomers.
[0011] Furthermore, the viscosity-reducing monomer is selected from one or more of alkyl acrylates, aminoalkyl acrylates, and hydroxyalkyl acrylates.
[0012] Furthermore, the macromonomer is selected from one or more of enol polyoxyethylene ether and alkenyl polyoxyethylene ether.
[0013] Further, in step S1, the mass ratio of chitosan to acrylic acid is (1-1.5):(0.2-0.6).
[0014] Furthermore, the chitosan is a chitosan oligosaccharide.
[0015] Further, in step S2, the mass ratio of the double-bonded chitosan, macromonomer, small-molecule monomer, and double-bonded polyethyleneimine is (1-3):(80-100):(20-40):(2-6).
[0016] Furthermore, in step S1, the temperature of the heating reaction is 20-80°C.
[0017] Furthermore, in step S2, the temperature of the heating reaction is 60-90°C.
[0018] Polyethyleneimine, a water-soluble cationic polymer rich in primary, secondary, and tertiary amines, is widely used in water treatment and flocculation due to its high-density positive charge and strong adsorption capacity. However, its application in polycarboxylate superplasticizers is relatively limited. This invention introduces polyethyleneimine into the polycarboxylate molecular backbone as a comonomer after double bond treatment. Utilizing its cationic properties, it enhances adsorption and regulates adsorption configuration, thereby promoting adsorption and dispersion, and preventing the superplasticizer backbone from failing due to soil coating, effectively improving the performance of the superplasticizer.
[0019] Another object of the present invention is to provide the application of the product prepared by the above-mentioned method for preparing high-strength concrete viscosity-reducing polycarboxylate superplasticizer in concrete.
[0020] The present invention has the following beneficial effects:
[0021] This invention discloses a method for preparing a high-strength concrete viscosity-reducing polycarboxylate superplasticizer. The method uses double-bonded chitosan, macromonomers, small monomers, and double-bonded polyethyleneimine as copolymer components. The double-bonded chitosan and polyethyleneimine possess numerous active sites such as amino and hydroxyl groups, which can synergistically interact with the carboxyl groups of acrylic acid, effectively improving the adsorption and binding effect on inorganic particles. Simultaneously, their multiple double bonds impart a network-like, three-dimensional branched structure to the polymer, enhancing steric hindrance and improving dispersion in conjunction with the long chains of polyoxyethylene ether. Furthermore, the three-dimensional barrier structure of the superplasticizer, combined with the water released by the hydrophobic alkyl groups reducing the overall hydration level, better exerts its lubricating function and reduces particle adhesion. Therefore, the polycarboxylate superplasticizer of this invention achieves a high water reduction rate at low dosages, meeting the requirements for low water-cement ratio formulations in high-strength concrete. In addition, the preparation method of this invention is simple, the reaction conditions are mild, and it does not contain components that may corrode steel reinforcement or concrete, which is of great significance to the development of concrete admixtures. Detailed Implementation
[0022] To more clearly illustrate the technical solution of the present invention, the following embodiments are provided. Unless otherwise stated, the raw materials, reactions, and post-processing methods appearing in the embodiments are all commercially available raw materials and technical methods well known to those skilled in the art.
[0023] The terms "preferred," "more preferably," and "more suitable" used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.
[0024] It should be understood that, except in any operational instance or otherwise indicated, all figures representing the amounts of ingredients used, for example, in the specification and claims, should be understood to be modified in all cases by the term "about". Therefore, unless otherwise stated, the numerical parameters set forth in the following specification and appended claims are approximations varying with the desired performance to be obtained according to the invention.
[0025] The allyl alcohol polyoxyethylene ether in the embodiments of the present invention is APEG-2400.
[0026] In this embodiment of the invention, the chitosan is a chitosan oligosaccharide with an average molecular weight ≤5000, purchased from Qingdao Yunzhou Biotechnology.
[0027] In this embodiment of the invention, the double-bonded polyethyleneimine is prepared in-house, and the preparation method includes the following steps:
[0028] Using dimethyl sulfoxide as solvent, 10 parts of polyethyleneimine (branched polyethyleneimine, purchased from Aladdin, Mn≈10000) were added and stirred to dissolve. Then, 0.5 parts of glycidyl methacrylate were added and stirred at 60°C for 48 h. After the reaction, acetone was added to precipitate the product. The precipitate was filtered, washed, and dried to obtain double-bonded polyethyleneimine.
[0029] In the embodiments of this invention, "parts" refers to parts by mass. Example 1
[0030] A method for preparing a high-strength concrete viscosity-reducing polycarboxylate superplasticizer, comprising the following steps:
[0031] S1. Take 1.1 parts chitosan, 0.7 parts EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide), and 0.3 parts NHS (N-hydroxysuccinimide). Stir and add 25 parts dilute hydrochloric acid (pH=4.7), then add 0.49 parts acrylic acid. Stir and react at room temperature for 72 h. Then add anhydrous ethanol to the reaction solution to precipitate. Filter and dry the precipitate to obtain double-bonded chitosan.
[0032] S2. Add 90 parts of allyl alcohol polyoxyethylene ether, 3 parts of the double-bonded chitosan, 5 parts of double-bonded polyethyleneimine, and 100 parts of water to a reactor. Then, at 80°C, simultaneously add a monomer solution (20 parts of acrylic acid, 5 parts of methyl acrylate, 0.6 parts of mercaptopropionic acid, and 30 parts of water, added over 3 hours) and an initiator solution (1 part of ammonium persulfate and 40 parts of water, added over 3.5 hours). After the addition is complete, keep the reaction at this temperature for 1.5 hours. After cooling to room temperature, adjust the pH to 5.5 with a 30 wt% sodium hydroxide aqueous solution to obtain a high-strength concrete viscosity-reducing polycarboxylate superplasticizer. Example 2
[0033] A method for preparing a high-strength concrete viscosity-reducing polycarboxylate superplasticizer, comprising the following steps:
[0034] S1. Take 1.1 parts chitosan, 0.7 parts EDC, and 0.3 parts NHS, stir and add 25 parts dilute hydrochloric acid (pH=4.7), then add 0.49 parts acrylic acid, stir and react at room temperature for 72 h, then add anhydrous ethanol to the reaction solution to precipitate, filter and dry the precipitate to obtain double-bonded chitosan.
[0035] S2. Add 95 parts of allyl alcohol polyoxyethylene ether, 3 parts of the double-bonded chitosan, 5 parts of double-bonded polyethyleneimine, and 100 parts of water to a reactor. Then, at 80°C, simultaneously add a monomer solution (20 parts of acrylic acid, 6 parts of ethyl acrylate, 0.6 parts of mercaptopropionic acid, and 30 parts of water, added over 3 hours) and an initiator solution (1 part of ammonium persulfate and 40 parts of water, added over 3.5 hours). After the addition is complete, keep the reaction at this temperature for 2 hours. After cooling to room temperature, adjust the pH to 5.5 with a 30 wt% sodium hydroxide aqueous solution to obtain a high-strength concrete viscosity-reducing polycarboxylate superplasticizer. Example 3
[0036] A method for preparing a high-strength concrete viscosity-reducing polycarboxylate superplasticizer, comprising the following steps:
[0037] S1. Take 1.1 parts chitosan, 0.7 parts EDC, and 0.3 parts NHS, stir and add 25 parts dilute hydrochloric acid (pH=4.7), then add 0.49 parts acrylic acid, stir and react at room temperature for 72 h, then add anhydrous ethanol to the reaction solution to precipitate, filter and dry the precipitate to obtain double-bonded chitosan.
[0038] S2. Add 85 parts of allyl alcohol polyoxyethylene ether, 3 parts of the double-bonded chitosan, 4 parts of double-bonded polyethyleneimine, and 100 parts of water to a reactor. Then, at 80°C, simultaneously add a monomer solution (20 parts of acrylic acid, 5 parts of methyl acrylate, 0.6 parts of mercaptopropionic acid, and 30 parts of water, added over 3 hours) and an initiator solution (1 part of ammonium persulfate and 40 parts of water, added over 3.5 hours). After the addition is complete, keep the reaction at the temperature for 1.5 hours. After cooling to room temperature, adjust the pH to 5.5 with a 30 wt% sodium hydroxide aqueous solution to obtain a high-strength concrete viscosity-reducing polycarboxylate superplasticizer. Comparative Example 1
[0039] The difference between this comparative example and Example 1 is that step S1 is deleted, and step S2 is modified as follows:
[0040] 90 parts of allyl alcohol polyoxyethylene ether and 100 parts of water were added to a reaction vessel. Then, monomer solution (20 parts of acrylic acid, 5 parts of methyl acrylate, 0.6 parts of mercaptopropionic acid and 30 parts of water, added dropwise over 3 hours) and initiator solution (1 part of ammonium persulfate and 40 parts of water, added dropwise over 3.5 hours) were added dropwise at 80°C. After the addition was complete, the reaction was kept at the temperature for 1.5 hours. After cooling to room temperature, the pH was adjusted to 5.5 with 30 wt% sodium hydroxide aqueous solution. Then, 3 parts of chitosan and 5 parts of polyethyleneimine were added and stirred evenly to obtain polycarboxylate superplasticizer. Comparative Example 2
[0041] The difference between this comparative example and Example 1 is that step S2 is modified as follows:
[0042] 90 parts of allyl alcohol polyoxyethylene ether, 3 parts of the double-bonded chitosan, and 100 parts of water were added to a reactor. Then, at 80°C, monomer solution (20 parts of acrylic acid, 5 parts of methyl acrylate, 0.6 parts of mercaptopropionic acid, and 30 parts of water, added dropwise over 3 hours) and initiator solution (1 part of ammonium persulfate and 40 parts of water, added dropwise over 3.5 hours) were added dropwise. After the addition was complete, the reaction was kept at this temperature for 1.5 hours. After cooling to room temperature, the pH was adjusted to 5.5 with a 30 wt% sodium hydroxide aqueous solution. Then, 5 parts of polyethyleneimine were added and stirred until homogeneous to obtain polycarboxylate superplasticizer. Test case
[0043] The water-reducing agents prepared in the examples and comparative examples were subjected to performance tests.
[0044] Concrete was prepared according to the formula in Table 1, with a water-reducing agent dosage of 1.2% (based on the mass of cementitious materials).
[0045] Table 1 Concrete Mix Proportions
[0046]
[0047] The rheological properties were determined using a concrete rheometer (NELD-CRH610).
[0048] The strength was determined according to GB / T 50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures".
[0049] The test results are shown in Table 2.
[0050] Table 2 Performance Test Results
[0051]
[0052] As can be seen from the test data in Table 2, the high-strength concrete viscosity-reducing polycarboxylate superplasticizer prepared in the examples can effectively perform adsorption, dispersion, and lubrication functions, and fully improve the water film structure on the surface of concrete particles, thus achieving the effects of increasing concrete strength and reducing viscosity. Comparative Example 1 did not modify the double bonds of chitosan and polyethyleneimine, directly blending them with the polycarboxylate superplasticizer. On the one hand, it could not introduce more active groups and branched stereostructures, reducing the adsorption effect; on the other hand, the compatibility and stability of the physically mixed system were insufficient, further weakening the viscosity-reducing and strengthening functions brought by the superplasticizer, resulting in the worst performance. Comparative Example 2 introduced double-bonded chitosan as a copolymer component, improving the adsorption and dispersion effects of the polymer, but the free polyethyleneimine still could not synergistically enhance the effect, resulting in less than ideal performance.
[0053] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.
[0054] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A method for preparing a high-strength concrete viscosity-reducing polycarboxylate superplasticizer, characterized in that, The preparation method of the high-strength concrete viscosity-reducing polycarboxylate superplasticizer includes the following steps: S1. Chitosan, catalyst and acrylic acid are mixed and heated to react, resulting in double-bonded chitosan; S2. Mix the double-bonded chitosan, macromonomer, small-molecule monomer, double-bonded polyethyleneimine and initiator, and heat to react to obtain a high-strength concrete viscosity-reducing polycarboxylate superplasticizer. The small molecule monomers include unsaturated carboxylic acid monomers and viscosity-reducing monomers.
2. The preparation method of the high-strength concrete viscosity-reducing polycarboxylate superplasticizer according to claim 1, characterized in that, The viscosity-reducing monomer is selected from one or more of alkyl acrylates, aminoalkyl acrylates, and hydroxyalkyl acrylates.
3. The preparation method of the high-strength concrete viscosity-reducing polycarboxylate superplasticizer according to claim 1, characterized in that, The macromonomer is selected from one or more of enol polyoxyethylene ether and alkenyl polyoxyethylene ether.
4. The preparation method of the high-strength concrete viscosity-reducing polycarboxylate superplasticizer according to claim 1, characterized in that, In step S1, the mass ratio of chitosan to acrylic acid is (1-1.5):(0.2-0.6).
5. The preparation method of the high-strength concrete viscosity-reducing polycarboxylate superplasticizer according to claim 4, characterized in that, The chitosan is a chitosan oligosaccharide.
6. The preparation method of the high-strength concrete viscosity-reducing polycarboxylate superplasticizer according to claim 1, characterized in that, In step S2, the mass ratio of the double-bonded chitosan, macromonomer, small monomer, and double-bonded polyethyleneimine is (1-3):(80-100):(20-40):(2-6).
7. The preparation method of the high-strength concrete viscosity-reducing polycarboxylate superplasticizer according to claim 1, characterized in that, In step S1, the temperature of the heating reaction is 20-80℃.
8. The preparation method of the high-strength concrete viscosity-reducing polycarboxylate superplasticizer according to claim 1, characterized in that, In step S2, the temperature of the heating reaction is 60-90℃.
9. The application of the product prepared by the method of preparing high-strength concrete viscosity-reducing polycarboxylate superplasticizer according to any one of claims 1-8 in concrete.