Cement concrete admixture as well as preparation method and application thereof
By adjusting the composition of cement concrete admixtures in a specific ratio, the problem of poor compatibility in sulfoaluminate cement systems was solved, achieving efficient water reduction and improved fluidity of cement concrete, thus improving its construction performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANDONG EXPRESSWAY INFRASTRUCTURE CONSTR CO LTD
- Filing Date
- 2026-03-04
- Publication Date
- 2026-05-26
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention relates to the field of concrete admixture preparation technology, specifically to a cement concrete admixture, its preparation method, and its application. Background Technology
[0002] Water-reducing agents are admixtures that can appropriately reduce the amount of mixing water and increase the strength of concrete while keeping the concrete slump and cement content constant, or can save cement content while keeping the workability and strength constant. They are classified as high-efficiency water-reducing agents.
[0003] Polycarboxylate superplasticizer is a high-performance water-reducing agent and a cement dispersant used in the transportation of cement concrete. It is widely used in projects such as highways, bridges, dams, tunnels, and high-rise buildings. This cement concrete admixture is non-flammable and non-explosive, making it safe for transport by train and truck. Polycarboxylate superplasticizers can increase the slump of concrete by 100-200 mm while keeping the water and cement dosage constant, significantly improving concrete fluidity without affecting its strength. Under the condition of maintaining fluidity and cement dosage, polycarboxylate superplasticizers can reduce the amount of mixing water by 10%-15%, thereby lowering the water-cement ratio and increasing concrete strength by 15%-20%. While maintaining fluidity and water-cement ratio, reducing mixing water can correspondingly reduce cement dosage, saving 10%-15% of cement while maintaining concrete strength, thus reducing project costs. Because the addition of superplasticizers significantly improves the pore structure of concrete, increasing its density and reducing permeability, it enhances its resistance to impermeability, frost damage, chemical corrosion, and rust. Furthermore, the use of superplasticizers can improve bleeding and segregation in concrete mixtures, delay setting time, slow down the heat release rate of cement hydration, and prevent cracks caused by internal and external temperature differences. Polycarboxylic acid (PCA) is a high-molecular-weight compound in resin form, possessing excellent strength, toughness, and chemical stability, making it suitable for a variety of applications. It offers advantages such as high water reduction with low dosage, resulting in good concrete fluidity, minimal slump loss, and wide cement compatibility.
[0004] Commercially available polycarboxylate admixtures have poor compatibility with sulfoaluminate cement systems due to fundamental differences in the chemical properties of sulfoaluminate cement and ordinary silicate cement, particularly in the differences in phase reactivity and ionic environment evolution during early hydration. Therefore, developing a cement concrete admixture suitable for sulfoaluminate cement is crucial to meeting market demands and driving industry development. Summary of the Invention
[0005] To address the shortcomings of existing technologies, the present invention aims to provide a cement concrete admixture, its preparation method, and its application, thereby solving the technical problem of poor compatibility of current cement concrete admixtures in sulfoaluminate cement systems. The cement concrete admixture prepared by adjusting its components exhibits high paste fluidity when applied to sulfoaluminate cement systems.
[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a cement concrete admixture, which, by weight, is prepared from the following raw materials: 30-40 parts methyl allyl alcohol polyoxyethylene ether, 4-8 parts acrylic acid, 2-4 parts modified cellulose, 1-2 parts sodium allyl sulfonate, 0.5-0.8 parts hydrogen peroxide, 0.05-0.1 parts ascorbic acid, 0.1-0.4 parts mercaptopropionic acid, and 60-80 parts water.
[0007] In the technical solution disclosed in this invention, the main chain of methyl allyl alcohol polyoxyethylene ether contains hydrophilic groups and provides long side chains (polyoxyethylene ether), which disperse cement particles through steric hindrance; the amount of methyl allyl alcohol polyoxyethylene ether can be selected from 30 parts by weight, 31 parts by weight, 32 parts by weight, 33 parts by weight, 34 parts by weight, 35 parts by weight, 36 parts by weight, 37 parts by weight, 38 parts by weight, 39 parts by weight, and 40 parts by weight, but is not limited to the listed values, and other unlisted values within the range are also applicable.
[0008] In the technical solution disclosed in this invention, the carboxylic acid groups of acrylic acid provide initial dispersing force, and reduce the agglomeration of cement particles through electrostatic repulsion. The amount of acrylic acid can be selected as 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, or 8 parts by weight, but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0009] In the technical solution disclosed in this invention, the preparation method of the modified cellulose is as follows: S1. Hydroxyethyl cellulose, aminosulfonic acid and urea are dissolved in N,N-dimethylformamide, heated and reacted, and then dialyzed, washed and dried to obtain sulfonated cellulose; S2. Sulfonated cellulose and triethylamine are dissolved in dimethyl sulfoxide, and then acryloyl chloride is added dropwise in an ice-water bath. After the addition is complete, the temperature is raised to room temperature, and the reaction is stirred in the dark. After the reaction is completed, the cellulose is precipitated, washed, and dried to obtain modified cellulose.
[0010] Specifically, in step S1, the weight ratio of hydroxyethyl cellulose, aminosulfonic acid, and urea is 10:3-6:0.5-1.5.
[0011] Specifically, in step S1, the temperature of the heating reaction is 80-90℃, and the heating reaction time is 3-5 hours.
[0012] Specifically, in step S2, the weight ratio of sulfonated cellulose, triethylamine, and acryloyl chloride is 10:1-2:0.5-1.5.
[0013] Specifically, in step S2, the stirring reaction time is 12-18 hours.
[0014] In the technical solution disclosed in this invention, sulfonation of cellulose introduces negatively charged sulfonic acid groups, which attract calcium ions on cement particles through electrostatic interaction. This causes the cement particles coated with admixtures to generate electrostatic repulsion due to the same charge, breaking the flocculation structure between cement particles and significantly improving the initial water reduction rate and flow velocity. Furthermore, by introducing carbon-carbon double bonds, modified cellulose can be introduced into the polycarboxylic acid macromolecular chain through copolymerization. The rigid cellulose skeleton and the flexible polyether side chains together construct a three-dimensional spatial network structure, which together improves the steric hindrance effect of the admixture.
[0015] The amount of modified cellulose can be 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, or 4 parts by weight, but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0016] In the technical solution disclosed in this invention, because modified cellulose contains polymerizable double bonds and has a macromolecular backbone, it is prone to localized overly rapid reactions, uncontrolled molecular weight, and even cross-linking and gelation during free radical polymerization, leading to decreased water solubility and poor stability of the product. Sodium allyl sulfonate contains double bonds and can enter the copolymerization system, but its allyl structure is relatively less reactive than acrylic monomers, thus playing a "buffering" role in polymerization. After copolymerization, sodium allyl sulfonate provides highly ionized sulfonate groups, enabling the water-reducing agent to form a stronger negative charge layer on the surface of cement particles, enhancing electrostatic repulsion to disperse the flocculated structure strengthened by the introduction of cellulose, thereby improving fluidity and workability without sacrificing water retention and anti-bleeding properties.
[0017] In the technical solution disclosed in this invention, the amount of sodium allyl sulfonate can be 1 part by weight, 1.5 parts by weight, or 2 parts by weight, but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0018] In the technical solution disclosed in this invention, hydrogen peroxide, as an oxidant in a redox system, rapidly decomposes at room temperature to release primary free radicals, initiating a copolymerization reaction of the double bonds in each monomer. The amount of hydrogen peroxide can be selected as 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, or 0.8 parts by weight, but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0019] In the technical solution disclosed in this invention, ascorbic acid, as a reducing agent in a redox system, synergistically lowers the activation energy of the polymerization reaction with hydrogen peroxide, achieving efficient aqueous copolymerization at room temperature or even low temperature. The amount of ascorbic acid can be selected from 0.05 parts by weight, 0.06 parts by weight, 0.07 parts by weight, 0.08 parts by weight, 0.09 parts by weight, or 0.1 parts by weight, but is not limited to the listed values; other unlisted values within the range are also applicable.
[0020] In the technical solution disclosed in this invention, mercaptopropionic acid is used as a chain transfer agent to effectively control the degree of polymerization of the main chain and suppress cross-linking side reactions. The amount of mercaptopropionic acid can be selected as 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, or 0.4 parts by weight, but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0021] In the technical solution disclosed in this invention, water is used as a solvent. The amount of water can be selected as 60 parts by weight, 62 parts by weight, 65 parts by weight, 68 parts by weight, 70 parts by weight, 72 parts by weight, 75 parts by weight, 78 parts by weight, or 80 parts by weight, but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0022] Secondly, the present invention provides a method for preparing the above-mentioned cement concrete admixture, comprising the following steps: adding methyl allyl alcohol polyoxyethylene ether, modified cellulose and sodium allyl sulfonate to water, stirring evenly, then adding hydrogen peroxide and ascorbic acid, mixing evenly, then adding acrylic acid and mercaptopropionic acid, heating and stirring to react, and after the reaction is completed, cooling to room temperature, adjusting the pH to 6-8, thereby obtaining the cement concrete admixture.
[0023] Specifically, the temperature for heating and stirring the reaction is 40-50℃, and the reaction time is 1-2 hours.
[0024] Thirdly, the present invention also provides the application of the above-mentioned cement concrete admixture in sulfoaluminate cement systems.
[0025] Compared with the prior art, the present invention has the following beneficial effects: (1) The cement concrete admixture provided by the present invention improves the overall performance of concrete through multiple synergistic copolymerization of polyether macromonomers, acrylic acid, modified cellulose and sodium allyl sulfonate in a specific ratio. Methyl allyl alcohol polyoxyethylene ether and acrylic acid form the main skeleton of the water-reducing agent, ensuring the steric hindrance and initial dispersion force of the foundation; by sulfonating cellulose, negatively charged sulfonic acid groups are introduced, which attract calcium ions on cement particles through electrostatic interaction, thereby generating electrostatic repulsion between cement particles coated with admixtures due to the same charge, which can break the flocculation structure between cement particles and significantly improve the initial water reduction rate and flow rate; and by introducing carbon-carbon double bonds, modified cellulose can be introduced into the polycarboxylic acid macromolecular chain through copolymerization reaction. The rigid cellulose skeleton and the flexible polyether side chain together construct a three-dimensional spatial network structure, which together improves the steric hindrance effect of the admixture.
[0026] (2) In view of the defects of modified cellulose macromolecules, which easily lead to cross-linking and gelation during synthesis and stickiness of the slurry during application, the present invention introduces sodium allyl sulfonate into the raw materials. Sodium allyl sulfonate contains double bonds and can enter the copolymerization system. However, its allyl structure is not as reactive as acrylic monomers, so it plays a "buffering" role in polymerization. Sodium allyl sulfonate provides sulfonate groups with high ionization after copolymerization, which makes the cement concrete admixture form a stronger negative charge layer on the surface of cement particles, enhances electrostatic repulsion to disperse the flocculation structure strengthened by the introduction of cellulose, and thus improves fluidity and workability without sacrificing water retention and anti-bleeding properties. Detailed Implementation
[0027] The present invention will be further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.
[0028] It should be noted that, unless otherwise specified, all chemical reagents involved in this invention were purchased through commercial channels.
[0029] The hydrogen peroxide used in this embodiment of the invention has a mass fraction of 30%.
[0030] Example 1
[0031] A method for preparing a cement concrete admixture includes the following steps: Add 30 parts of methyl allyl alcohol polyoxyethylene ether, 2 parts of modified cellulose and 1 part of sodium allyl sulfonate to 60 parts of water and stir well. Then add 0.5 parts of hydrogen peroxide and 0.05 parts of ascorbic acid and mix well. Then add 4 parts of acrylic acid and 0.1 parts of mercaptopropionic acid. Heat to 40°C and stir for 2 hours. After the reaction is complete, cool to room temperature and adjust the pH to 7 with NaOH solution to obtain the cement concrete admixture.
[0032] The preparation method of modified cellulose is as follows: S1. Dissolve 10 parts of hydroxyethyl cellulose, 3 parts of aminosulfonic acid and 0.5 parts of urea in 100 parts of N,N-dimethylformamide and carry out the reaction by heating at 80°C for 5 hours. After the reaction is completed, sulfonated cellulose is obtained by dialysis, washing and drying. S2. Dissolve 10 parts of sulfonated cellulose and 1 part of triethylamine in 100 parts of dimethyl sulfoxide, and then add 0.5 parts of acryloyl chloride dropwise in an ice-water bath. After the addition is complete, heat to room temperature and stir the reaction in the dark for 12 hours. After the reaction is complete, precipitate, wash and dry to obtain modified cellulose.
[0033] Example 2
[0034] A method for preparing a cement concrete admixture includes the following steps: Add 40 parts of methyl allyl alcohol polyoxyethylene ether, 4 parts of modified cellulose and 2 parts of sodium allyl sulfonate to 80 parts of water and stir until homogeneous. Then add 0.8 parts of hydrogen peroxide and 0.1 parts of ascorbic acid and mix until homogeneous. Subsequently, add 8 parts of acrylic acid and 0.4 parts of mercaptopropionic acid, heat to 45°C, and stir for 1.5 hours. After the reaction is complete, cool to room temperature and adjust the pH to 7 with NaOH solution to obtain the cement concrete admixture.
[0035] The preparation method of modified cellulose is as follows: S1. Dissolve 10 parts of hydroxyethyl cellulose, 6 parts of aminosulfonic acid and 1.5 parts of urea in 100 parts of N,N-dimethylformamide and carry out the reaction by heating at 80°C for 5 hours. After the reaction is completed, sulfonated cellulose is obtained by dialysis, washing and drying. S2. Dissolve 10 parts of sulfonated cellulose and 2 parts of triethylamine in 100 parts of dimethyl sulfoxide, and then add 1.5 parts of acryloyl chloride dropwise in an ice-water bath. After the addition is complete, heat to room temperature and stir the reaction in the dark for 12 hours. After the reaction is complete, precipitate, wash and dry to obtain modified cellulose.
[0036] Example 3
[0037] A method for preparing a cement concrete admixture includes the following steps: Add 35 parts of methyl allyl alcohol polyoxyethylene ether, 3 parts of modified cellulose and 1.5 parts of sodium allyl sulfonate to 65 parts of water and stir well. Then add 0.6 parts of hydrogen peroxide and 0.08 parts of ascorbic acid and mix well. Then add 5 parts of acrylic acid and 0.2 parts of mercaptopropionic acid. Heat to 50°C and stir for 1 hour. After the reaction is complete, cool to room temperature and adjust the pH to 7 with NaOH solution to obtain the cement concrete admixture.
[0038] The preparation method of modified cellulose is as follows: S1. Dissolve 10 parts of hydroxyethyl cellulose, 5 parts of aminosulfonic acid and 1 part of urea in 100 parts of N,N-dimethylformamide and carry out the reaction by heating at 90°C for 3 hours. After the reaction is completed, sulfonated cellulose is obtained by dialysis, washing and drying. S2. Dissolve 10 parts of sulfonated cellulose and 1.5 parts of triethylamine in 100 parts of dimethyl sulfoxide, and then add 1 part of acryloyl chloride dropwise in an ice-water bath. After the addition is complete, heat to room temperature and stir the reaction in the dark for 12 hours. After the reaction is complete, precipitate, wash and dry to obtain modified cellulose.
[0039] Comparative Example 1 A method for preparing a cement concrete admixture includes the following steps: Add 30 parts of methyl allyl alcohol polyoxyethylene ether, 2 parts of modified cellulose and 1 part of sodium allyl sulfonate to 60 parts of water and stir well. Then add 0.5 parts of hydrogen peroxide and 0.05 parts of ascorbic acid and mix well. Then add 4 parts of acrylic acid and 0.1 parts of mercaptopropionic acid. Heat to 40°C and stir for 2 hours. After the reaction is complete, cool to room temperature and adjust the pH to 7 with NaOH solution to obtain the cement concrete admixture.
[0040] The preparation method of modified cellulose is as follows: Dissolve 10 parts of hydroxyethyl cellulose and 1 part of triethylamine in 100 parts of dimethyl sulfoxide, and then add 0.5 parts of acryloyl chloride dropwise in an ice-water bath. After the addition is complete, heat to room temperature and stir the mixture in the dark for 12 hours. After the reaction is complete, the cellulose is obtained by precipitation, washing and drying.
[0041] Compared to Comparative Example 1 and Example 1, hydroxyethyl cellulose was not sulfonated.
[0042] Comparative Example 2 A method for preparing a cement concrete admixture includes the following steps: Add 30 parts of methyl allyl alcohol polyoxyethylene ether, 2 parts of modified cellulose and 1 part of sodium allyl sulfonate to 60 parts of water and stir well. Then add 0.5 parts of hydrogen peroxide and 0.05 parts of ascorbic acid and mix well. Then add 4 parts of acrylic acid and 0.1 parts of mercaptopropionic acid. Heat to 40°C and stir for 2 hours. After the reaction is complete, cool to room temperature and adjust the pH to 7 with NaOH solution to obtain the cement concrete admixture.
[0043] The preparation method of modified cellulose is as follows: 10 parts of hydroxyethyl cellulose, 3 parts of aminosulfonic acid and 0.5 parts of urea were dissolved in 100 parts of N,N-dimethylformamide and heated to react at 80°C for 5 hours. After the reaction was completed, the cellulose was obtained by dialysis, washing and drying.
[0044] Compared with Example 1, no double bonds were introduced into cellulose in Comparative Example 2.
[0045] Comparative Example 3 A method for preparing a cement concrete admixture includes the following steps: Add 30 parts of methyl allyl alcohol polyoxyethylene ether and 2 parts of modified cellulose to 60 parts of water and stir until homogeneous. Then add 0.5 parts of hydrogen peroxide and 0.05 parts of ascorbic acid and mix until homogeneous. Subsequently, add 4 parts of acrylic acid and 0.1 parts of mercaptopropionic acid, heat to 40°C, and stir for 2 hours. After the reaction is complete, cool to room temperature and adjust the pH to 7 with NaOH solution to obtain the cement concrete admixture.
[0046] The preparation method of modified cellulose is as follows: S1. Dissolve 10 parts of hydroxyethyl cellulose, 3 parts of aminosulfonic acid and 0.5 parts of urea in 100 parts of N,N-dimethylformamide and carry out the reaction by heating at 80°C for 5 hours. After the reaction is completed, sulfonated cellulose is obtained by dialysis, washing and drying. S2. Dissolve 10 parts of sulfonated cellulose and 1 part of triethylamine in 100 parts of dimethyl sulfoxide, and then add 0.5 parts of acryloyl chloride dropwise in an ice-water bath. After the addition is complete, heat to room temperature and stir the reaction in the dark for 12 hours. After the reaction is complete, precipitate, wash and dry to obtain modified cellulose.
[0047] Compared with Example 1, sodium allyl sulfonate was not added to the raw materials in Comparative Example 3.
[0048] The cement concrete admixtures prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests, as detailed below: Cement paste fluidity test: The test is conducted according to GB / T 8077-2012 "Test Method for Homogeneity of Concrete Admixtures". The specific steps are as follows: (1) Place a glass plate with dimensions of 400mm×400mm×5mm in a horizontal position, and wipe the glass plate, truncated cone mold, stirrer and mixing pot with a damp cloth to make its surface wet but without water stains. (1) Place the truncated cone mold in the center of the glass plate and cover it with a damp cloth for later use; (2) Weigh 300g of cement (L·SAC 42.5 grade), pour it into the mixing pot, and then weigh 0.3% of the water-reducing agent (based on the cement mass) into 105g of water and mix it with the cement; (3) Pour the mixed cement paste into the cement paste mixer, stir for 120s, let it stand for 15s, and then stir it quickly for 120s; (4) Pour the mixed cement into the truncated cone mold placed on the glass plate, balance the truncated cone mold, and then lift the truncated cone mold in the vertical direction so that the cement flows freely on the glass plate for 30s until the cement paste no longer expands; (5) Measure the maximum length in the vertical direction with a steel ruler, take the average value as the test result of the cement paste fluidity, and measure the paste fluidity for 120 minutes. Concrete was prepared in accordance with standard JGJ 55-2011 "Ordinary Concrete Mix Design Engineering". The mix proportions used were: 360 kg of cement (L·SAC 42.5 grade), 800 kg of river sand, 900 kg of aggregate (15-25 mm), 7.2 kg of cement concrete admixture prepared in Examples 1-3 and Comparative Examples 1-3, and 170 kg of water. The compressive strength of the prepared concrete was determined in accordance with GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete". The test results are shown in Table 1.
[0049] Table 1 Performance test results for different groups
[0050] Finally, it should be noted that the above embodiments do not limit the present invention in any way. Those skilled in the art can make modifications and improvements based on the present invention. Therefore, any modifications or improvements made without departing from the spirit of the present invention are within the scope of protection claimed by the present invention.
Claims
1. A cement concrete admixture, characterized in that, The cement concrete admixture, by weight, is prepared from the following raw materials: 30-40 parts methyl allyl alcohol polyoxyethylene ether, 4-8 parts acrylic acid, 2-4 parts modified cellulose, 1-2 parts sodium allyl sulfonate, 0.5-0.8 parts hydrogen peroxide, 0.05-0.1 parts ascorbic acid, 0.1-0.4 parts mercaptopropionic acid, and 60-80 parts water.
2. The cement concrete admixture according to claim 1, characterized in that, The modified cellulose is prepared as follows: S1. Hydroxyethyl cellulose, aminosulfonic acid and urea are dissolved in N,N-dimethylformamide, heated and reacted, and then dialyzed, washed and dried to obtain sulfonated cellulose; S2. Sulfonated cellulose and triethylamine are dissolved in dimethyl sulfoxide, and then acryloyl chloride is added dropwise in an ice-water bath. After the addition is complete, the temperature is raised to room temperature, and the reaction is stirred in the dark. After the reaction is completed, the cellulose is precipitated, washed, and dried to obtain modified cellulose.
3. The cement concrete admixture according to claim 2, characterized in that, In step S1, the weight ratio of hydroxyethyl cellulose, aminosulfonic acid and urea is 10:3-6:0.5-1.
5.
4. The cement concrete admixture according to claim 2, characterized in that, In step S1, the temperature of the heating reaction is 80-90℃, and the heating reaction time is 3-5h.
5. The cement concrete admixture according to claim 2, characterized in that, In step S2, the weight ratio of sulfonated cellulose, triethylamine and acryloyl chloride is 10:1-2:0.5-1.
5.
6. The cement concrete admixture according to claim 2, characterized in that, In step S2, the stirring reaction time is 12-18 hours.
7. The method for preparing the cement concrete admixture according to any one of claims 1-6, characterized in that, The process includes the following steps: adding methyl allyl alcohol polyoxyethylene ether, modified cellulose, and sodium allyl sulfonate to water and stirring until homogeneous; then adding hydrogen peroxide and ascorbic acid and mixing until homogeneous; subsequently adding acrylic acid and mercaptopropionic acid; heating and stirring to react; after the reaction is complete, cooling to room temperature and adjusting the pH to 6-8 to obtain the cement concrete admixture.
8. The preparation method according to claim 7, characterized in that, The temperature for heating and stirring during the reaction is 40-50℃, and the reaction time is 1-2 hours.
9. The application of the cement concrete admixture as described in any one of claims 1-6 in a sulfoaluminate cement system.