Efficient concrete adapter and preparation method thereof

Abstract

The invention provides an efficient concrete adapter and a preparation method thereof. The high-efficiency adapter is prepared by compounding a viscosity adjusting dispersant, a sacrificial agent and polymeric polyol, wherein the viscosity adjusting dispersant is a low-molecular-weight polymer prepared by carrying out addition on 1-octylene-3-alcohol and epoxide and then polymerizing with diethylene glycol monovinyl ether; the sacrificial agent is a small molecular weight polymer prepared by polymerizing n-butylamine and epoxide. According to the invention, the polyether monomer and the small-molecule polymer are prepared and compounded, so that the particle dispersity is improved, the use of the water reducing agent is not influenced, the performance of other additives is ensured, and the adverse effects of various factors on concrete are prevented.

Description

Technical Field

[0001] This invention belongs to the field of concrete technology and relates to a polyether-based concrete admixture, specifically a high-efficiency concrete admixture and its preparation method. Background Technology

[0002] With economic development, concrete is playing an increasingly important role in numerous water conservancy, bridge, tunnel, and subway projects. The addition of admixtures affects the quality, compressive strength, impermeability, frost resistance, durability, and service life of concrete.

[0003] Traditional polycarboxylate superplasticizers are characterized by high water reduction rates and low dosage. However, excessive dosage can lead to segregation, bleeding, or excessive air content. At a certain dosage, the fluidity of cement paste decreases, indicating a limit to the water-reducing effect. Beyond this limit, the cement's fluidity decreases, and the water-reducing effect deteriorates. In actual production, the admixture dosage fluctuates with other materials, which is acceptable as long as the fluctuation is small. However, concrete loss is also a serious problem compared to dosage fluctuations.

[0004] Patent CN115716724A discloses a concrete hydration enhancer and its preparation method. The concrete hydration enhancer is polymerized from acrylic acid, maleimide alkyl acid, maleimide, acrylic acid-maleic acid-acrylamide copolymer, maleic anhydride binary copolymer, glyceryl acrylate, chain transfer agent, and initiator. This concrete hydration enhancer can fully promote the dispersion of cement and increase its hydration rate without affecting the setting time of concrete, thereby improving the concrete strength and cement utilization rate, and avoiding the waste caused by using unhydrated cement as filler.

[0005] Patent CN115505071A discloses a method for preparing a high-performance polycarboxylate superplasticizer with low sensitivity to mud content in concrete. This invention uses methyl allyl polyoxyethylene ether and acrylic acid as reactive monomers, and β-cyclodextrin maleic acid monoester as a functional monomer to prepare modified polycarboxylate superplasticizers with different single functional groups through copolymerization reaction. The superplasticizer modified by β-cyclodextrin has significantly reduced sensitivity to soil, thus greatly facilitating its use.

[0006] To reduce the sensitivity of concrete water-reducing agents under various conditions, researchers usually follow the traditional molecular design approach for water-reducing agents, but functional modifications also have many negative effects.

[0007] Unlike the above patents, in order to reduce sensitivity while ensuring the normal efficacy of water-reducing agents, a high-efficiency adaptor is proposed: A high-efficiency adaptor composed of a dispersant and a sacrificial agent is prepared using addition reaction and free radical polymerization methods. The smaller molecular conformation of the dispersant allows it to remain free within the gaps between particles; the lack of polar groups such as carboxyl and sulfonic acid groups in its structure prevents it from prematurely occupying the adsorption sites of the water-reducing agent and affecting its function; the sacrificial agent acts on impurities in the clay in the concrete, draining water from between clay layers, ultimately improving particle dispersibility while ensuring the performance of other admixtures and preventing adverse effects on the concrete from various factors. Summary of the Invention

[0008] The technical problem to be solved by this invention is to provide a high-efficiency concrete admixture. The polymer prepared by this invention has a mature preparation process, excellent product performance, good stability, and wide applicability.

[0009] To solve the above problems, the technical solution of the present invention is as follows: A high-efficiency concrete compatibilizer is prepared as follows: (1) Preparation of viscosity-modifying dispersant Step 1: Add 46.00~79.29 parts of alcohol head and 1.0~2.2 parts of catalyst to a high-pressure reactor. After several nitrogen purgings, start evacuating to a gauge pressure of -0.1MPa. Then, raise the temperature to 120~130℃ to start dehydration for 1~2 hours. After cooling to 115℃, start continuously introducing 72.44~110.64 parts of cyclic monomer, controlling the pressure to be less than 0.4MPa. After all the cyclic monomer has been introduced, keep the temperature at 110~120℃ for 1.5~2.5 hours to react until negative pressure is reached. Cool down and discharge to obtain polyether monomer. Step 2: Add the obtained polyether monomer to the reactor and heat it to 55-65℃ using a water bath, then maintain the temperature. Prepare solution A by mixing 5.6-8.6 parts of initiator, 1.2-4.8 parts of chain transfer agent, and water. Prepare solution B by mixing 165.97-171.63 parts of ether, 3.2-7.9 parts of reducing agent, and water. Add solutions A and B dropwise simultaneously, with solution A added over 2-2.5 hours and solution B over 1.5-2 hours. After adding solution A, maintain the temperature for 1 hour. Add 5.9-9.4 parts of neutralizing agent at once, then add water to a final volume of 1000 parts to obtain a 30% viscosity-adjusting dispersant mother liquor. (2) Preparation of sacrificial agent Add 53.89~74.18 parts of amine head to a high-pressure reactor, and while evacuating, raise the temperature to 160~170℃, maintaining the reactor pressure at 0.2~0.3MPa. The material inside the reactor is drawn out and then sprayed back in from the top, along with cyclic monomers. After this cycle is repeated for a period, maintain the temperature and cool to 90~100℃. Add 1.0~2.2 parts of catalyst and purge with nitrogen. Begin evacuating to a gauge pressure of -0.1MPa, then raise the temperature to 165~170℃. Begin introducing the remaining cyclic monomers into the reactor, totaling 225.83~246.10 parts. Control the pressure to less than 0.4MPa and maintain the circulating spray for 2.0~2.5 hours. After the reaction is complete, maintain the temperature for 1 hour. Add 11.9~13.4 parts of neutralizing agent at once, then add water to a final volume of 1000 parts to obtain a 30% sacrificial agent mother liquor. (3) Preparation of high-efficiency adaptants The prepared viscosity-adjusting dispersant, sacrificial agent, and multi-component polymeric alcohol were compounded in a ratio of 2:1:5, and water was added to bring the total volume to 1000 parts to obtain a 50% high-efficiency adaptant mother liquor.

[0010] The high-efficiency adaptor mother liquor was diluted at a ratio of 1:29 to obtain the high-efficiency adaptor working solution, and its dosage was 0.5%.

[0011] Preferably, the alcohol head is 1-octen-3-ol.

[0012] Preferably, the catalyst is one of sodium hydroxide, potassium hydroxide, and sodium methoxide, with sodium hydroxide being the most preferred.

[0013] Preferably, the cyclic monomer is one or more of ethylene oxide and propylene oxide, and the viscosity modifier dispersant is a mixture of ethylene oxide and propylene oxide with a molar ratio of cyclic monomers of 2 to 6:1, most preferably 4.2:1; the sacrificial agent is a mixture of ethylene oxide and propylene oxide with a molar ratio of cyclic monomers of 5:1.

[0014] Preferably, the initiator is one of ammonium persulfate, diisopropyl peroxide, and dihexyl peroxide, with diisopropyl peroxide being the most preferred; the chain transfer agent is one of mercaptoacetic acid, mercaptoethanol, and mercaptopropionic acid, with mercaptopropionic acid being the most preferred; and the ether is diethylene glycol monovinyl ether.

[0015] Preferably, the amine head is n-butylamine; the reducing agent is sodium hypophosphite; and the neutralizing agent is potassium carbonate.

[0016] Preferably, the alcohol-ether ratio is 2.1 to 3.5:1, and most preferably 2.7:1.

[0017] Preferably, the polymeric polyol is composed of several of the following: ethylene glycol, glycerol, triglyceride, and triethanolamine.

[0018] Preferably, the viscosity-regulating dispersant, sacrificial agent, and polymeric polyol are in a ratio of 2:1:5.

[0019] This invention primarily focuses on polymer functional design based on the reaction of terminal hydroxyl groups of alcohol heads with epoxy monomers. Through the etherification of alcohol heads and epoxy groups, a low molecular weight polymer of approximately 4000 is synthesized. Ethylene oxide and propylene oxide are selected as the epoxy substances. By adjusting the grafting ratio of ethylene oxide and propylene oxide, the number of methyl groups can be adjusted, thereby flexibly changing the polymer's viscosity-reducing or viscosity-increasing properties. Unlike water-reducing agents, this highly efficient adaptor lacks anchoring groups to avoid competitive adsorption with other additives or occupying the active sites of particles, which would prevent the water-reducing agent from adsorbing and thus become ineffective.

[0020] The molecular weight of the dispersant is small enough compared to traditional water-reducing agents, allowing the high-efficiency adaptor to act in the narrow space that the large molecules of the water-reducing agent cannot enter, thereby exerting a dispersing effect, increasing the contact area between the particles and water, and accelerating the hydration process. The adsorption capacity of hydroxyl groups is relatively weak, so the high-efficiency adaptor is in a dynamic process of adsorption-desorption during the hydration process, and will not produce performance sensitivity phenomena.

[0021] Based on this structural characteristic, when this high-efficiency adaptor is used in combination with other admixtures, it will not produce competitive adsorption. Moreover, its small molecular conformation allows it to act on parts that water-reducing agents cannot reach, thus effectively improving the performance of cement products.

[0022] The low molecular weight sacrificial agent in the high-efficiency compatibility agent does not have a clearly directional polar group in its structure. It will not interact with cement particles, but will intercalate with clay impurities in concrete. It can drain water between clay layers and prevent clay from having an adverse effect on concrete performance.

[0023] The beneficial effects of the present invention are as follows: 1. The dispersing component in the high-efficiency adaptor provided by the present invention has a molecular weight concentrated at around 4000, which can effectively enter the gaps between particles and provide a dispersing effect.

[0024] 2. The dispersing component in the high-efficiency adaptor provided by the present invention does not contain strongly adsorbing anchoring groups. The adsorption capacity of hydroxyl groups is weaker than that of carboxyl and sulfonic acid groups, so that it is in a dynamic process of adsorption-desorption during hydration and will not produce sensitive phenomena.

[0025] 3. The sacrificial agent component in the high-efficiency adaptant provided by the present invention can effectively intercalate with impurities such as clay in concrete, drain interlayer water, increase fluidity, and promote particle hydration. Detailed Implementation

[0026] The applicant will further describe the technical solution and beneficial effects of the present invention in detail with reference to specific embodiments. The following embodiments should not be construed as limiting the scope of protection claimed in the claims of this application in any way. The adaptants prepared in Examples 1-6 are compared with blank samples without adaptants and comparative samples with common commercially available water-reducing agents.

[0027] Performance testing: Bleeding rate: The bleeding rate was determined according to GB8076—2008 "Concrete Admixtures"; Flowability and water reduction rate: The test methods were carried out according to the national standard GB 8077-2012 "Test Method for Homogeneity of Concrete Admixtures". The experimental results are shown in Tables 3 and 4.

[0028] Table 1. Raw material composition for the preparation of high-efficiency adaptants

[0029]

[0030]

[0031] Table 2 Preparation process of high-efficiency adaptants

[0032] Table 3 Results of the fluidity test of the paste

[0033] Table 4 Performance test results under muddy conditions

[0034] As shown in Tables 3 and 4, the high-efficiency adaptant synthesized by the method of the present invention, when combined with the water-reducing agent, has a significant effect on the fluidity of the cement paste, proving that the dispersant component has a significant dispersing effect on the particle hydration process; it also exhibits good slump, water reduction rate and bleeding rate in the concrete system. Attached Figure Description Figure 1 GPC test chromatograms for highly efficient adaptants. As shown in the figure, the highly efficient adaptor obtained through free radical polymerization has a high conversion rate, a dispersion coefficient of 1.017, and a polymer molecular weight concentrated around 3000. The smaller molecular weight ensures the polymer remains free within the gaps between particles. The absence of polar groups in the molecular structure ensures it occupies the adsorption sites of the water-reducing agent, thus influencing the agent's function. Simultaneously, the sacrificial agent acts on impurities in the clay within the concrete, draining water from between clay layers. Ultimately, this improves particle dispersibility while maintaining the performance of the water-reducing agent and preventing adverse effects on the concrete from various factors.

[0035] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0036] Table 5. Molecular weight of dispersant polymers

Claims

1. A high-efficiency concrete admixture, characterized in that, The preparation process is as follows, and all the following parts are by weight: (1) Preparation of viscosity-modifying dispersants Step 1: Add 46.00~79.29 parts of alcohol head and 1.0~2.2 parts of catalyst to a high-pressure reactor. After several nitrogen purgings, start evacuating to a gauge pressure of -0.1MPa. Then, raise the temperature to 120~130℃ to start dehydration for 1~2 hours. After cooling to 115℃, start continuously introducing 72.44~110.64 parts of cyclic monomer, controlling the pressure to be less than 0.4MPa. After all the cyclic monomer has been introduced, keep the temperature at 110~120℃ for 1.5~2.5 hours to react until negative pressure is reached. Cool down and discharge to obtain polyether monomer. Step 2: Add the obtained polyether monomer to the reactor and heat it to 55-65℃ using a water bath, then maintain the temperature. Prepare solution A by mixing 5.6-8.6 parts of initiator, 1.2-4.8 parts of chain transfer agent, and water. Prepare solution B by mixing 165.97-171.63 parts of ether, 3.2-7.9 parts of reducing agent, and water. Add solutions A and B dropwise simultaneously, with solution A added over 2-2.5 hours and solution B over 1.5-2 hours. After adding solution A, maintain the temperature for 1 hour. Add 5.9-9.4 parts of neutralizing agent at once, then add water to a final volume of 1000 parts to obtain a 30% viscosity-adjusting dispersant mother liquor. (2) Preparation of sacrificial agent Add 53.89~74.18 parts of amine head to a high-pressure reactor, and while evacuating, raise the temperature to 160~170℃, maintaining the reactor pressure at 0.2~0.3MPa. The material inside the reactor is drawn out and then sprayed back in from the top, along with cyclic monomers. After this cycle is repeated for a period, maintain the temperature and cool to 90~100℃. Add 1.0~2.2 parts of catalyst and purge with nitrogen. Begin evacuating to a gauge pressure of -0.1MPa, then raise the temperature to 165~170℃. Begin introducing the remaining cyclic monomers into the reactor, totaling 225.83~246.10 parts. Control the pressure to less than 0.4MPa and maintain the circulating spray for 2.0~2.5 hours. After the reaction is complete, maintain the temperature for 1 hour. Add 11.9~13.4 parts of neutralizing agent at once, then add water to a final volume of 1000 parts to obtain a 30% sacrificial agent mother liquor. (3) Preparation of high-efficiency adaptants The prepared viscosity-adjusting dispersant, sacrificial agent, and multi-component polymeric alcohol were compounded in a ratio of 2:1:5, and water was added to bring the total volume to 1000 parts to obtain a 50% high-efficiency adaptant mother liquor.

2. The high-efficiency concrete admixture according to claim 1, characterized in that, The alcohol head is 1-octen-3-ol.

3. The high-efficiency concrete admixture according to claim 1, characterized in that, The catalyst is one of sodium hydroxide, potassium hydroxide, and sodium methoxide.

4. The high-efficiency concrete admixture according to claim 1, characterized in that, The cyclic monomer is one or more of ethylene oxide and propylene oxide; the viscosity modifier dispersant is a mixture of ethylene oxide and propylene oxide with a molar ratio of cyclic monomers of 2 to 6:1; the sacrificial agent is a mixture of ethylene oxide and propylene oxide with a molar ratio of cyclic monomers of 5:

1.

5. The high-efficiency concrete admixture according to claim 1, characterized in that, The initiator is one of ammonium persulfate, diisopropyl peroxide dicarbonate, or dihexyl peroxide dicarbonate; the chain transfer agent is one of mercaptoacetic acid, mercaptoethanol, or mercaptopropionic acid; and the ether is diethylene glycol monovinyl ether.

6. The high-efficiency concrete admixture according to claim 1, characterized in that, The amine head is n-butylamine; the reducing agent is sodium hypophosphite; and the neutralizing agent is potassium carbonate.

7. The high-efficiency concrete admixture according to claim 1, characterized in that, The alcohol-ether ratio is 2.1~3.5:

1.

8. The high-efficiency concrete admixture according to claim 1, characterized in that, The polymeric polyol is composed of several of the following: ethylene glycol, glycerol, triglyceride, and triethanolamine.

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