Functional monomer, shrinkage-reducing type water reducing agent, cement-based material shrinkage-reducing anti-cracking additive and preparation method of cement-based material shrinkage-reducing anti-cracking additive
By using the shrinkage-reducing water reducer prepared by functional monomers in concrete, the problem of concrete shrinkage and cracking is reduced, and the problem of threat of durability and safety of concrete in extreme environments is solved, achieving significant shrinkage and crack resistance.
Patent Information
- Application Number
- CN202411890357.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-20
- Publication Date
- 2025-04-22
AI Technical Summary
Concrete is prone to cracking during shrinkage, which leads to the threat of the durability and safety of the structure, especially in extreme environments.
A functional monomer is adopted to reduce the surface tension of the concrete pore solution by introducing the polyether compound of tetraalkoxysilane into the shrinkage water reducing agent, slowing down the cement hydration process, and to increase the supersaturation and crystallization pressure of calcium hydroxide and ettringite by changing the pore solution ion concentration, forming an internal stress compensation mechanism.
It effectively reduces the shrinkage of concrete, prevents cracking, improves the durability and safety of concrete, and is suitable for concrete structures used in extreme environments.
Smart Images
Figure QLYQS_1 
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of building admixtures, and in particular to a functional monomer, a shrinkage-reducing water-reducing agent, a cement-based material shrinkage-reducing and anti-cracking admixture and a preparation method thereof. Background Art
[0002] As one of the most widely used materials in modern construction projects, the performance of concrete is directly related to the safety, durability and use function of engineering structures. However, the shrinkage cracking problem of concrete has always been a severe challenge faced by the engineering community. In many concrete structures, most cracks are caused by different types of shrinkage deformation. These shrinkage cracks not only destroy the appearance integrity of the concrete structure, but more seriously, they will cause leakage in the structure, provide channels for the invasion of harmful ions, accelerate the deterioration process such as steel corrosion, and thus seriously threaten the long-term safety of the structure and significantly shorten its service life.
[0003] With the rapid development of infrastructure construction in my country, many major engineering projects are constantly moving towards extreme environments such as plateaus, deserts, and oceans. In these special areas, harsh conditions such as large temperature differences, extreme dryness, and strong corrosion place higher demands on concrete performance. At the same time, the increasing scarcity of high-quality raw material resources has led to the increasing use of industrial waste slag in concrete production, making the composition of concrete more complex and diverse. Against this complex background, the shrinkage cracking phenomenon of concrete and the damage it causes have become increasingly prominent, becoming a key technical problem that needs to be solved urgently. Summary of the invention
[0004] The present invention aims to overcome the problem of concrete shrinkage cracking, reduce concrete shrinkage, meet the crack resistance requirements, and provide a functional monomer with the following structural formula: ; Among them, R 1 is a hydrocarbon group of 1 to 20 carbon atoms, a is an integer of 1 to 4, b is an integer of 5 to 30, and m is an integer of 0 to 3.
[0005] The present invention also provides a method for preparing a functional monomer, comprising the following steps: adding 3 to 5 parts of tetraalkoxysilane, 30 to 60 parts of unsaturated polyether, 0.03 to 0.08 parts of p-toluenesulfonic acid or acetic acid, 1 to 5 parts of methanol and 0.3 to 0.9 parts of water by weight into a container equipped with a thermometer and a vacuum distiller, heating to 50 to 60° C., reacting for 2 to 5 hours, continuing to heat to 105 to 120° C., reacting for 2 to 5 hours, and distilling under reduced pressure to discharge methanol to obtain the functional monomer.
[0006] On the basis of the above technical solution, the molecular weight of the unsaturated polyether is further 500-1000.
[0007] The present invention also provides a shrinkage-reducing water-reducing agent, which is prepared by polymerization reaction of vinyl polyether macromonomer, unsaturated carboxylic acid, and functional monomer in a mass ratio of (60-100): (10-20): (10-40) in the presence of water, an initiator, and a chain transfer agent; The structural formula of the functional monomer is as follows: ; Among them, R 1 is a hydrocarbon group of 1 to 20 carbon atoms, a is an integer of 1 to 4, b is an integer of 5 to 30, and m is an integer of 0 to 3.
[0008] On the basis of the above technical solution, further, the initiator is a hydrogen peroxide-reducing agent system; The reducing agent is at least one of bisulfite, sulfite, bleaching agent and vitamin C.
[0009] On the basis of the above technical solution, further comprising the following steps: 10-40 parts of functional monomers, 60-100 parts of vinyl polyether macromonomers, 1-2 parts of hydrogen peroxide, and 50-100 parts of water are added to a reaction kettle by weight, the temperature is controlled at 20-25°C, and a reducing agent aqueous solution, an unsaturated carboxylic acid aqueous solution, and a chain transfer agent aqueous solution are added dropwise for 3-4 hours. After the addition is completed, the temperature is kept for 1-2 hours, and water is added to adjust the concentration to obtain a reaction product of 50%; The pH of the reaction product is adjusted to 6.0-7.0 with sodium hydroxide to obtain a shrinkage-reducing water-reducing agent.
[0010] On the basis of the above technical solution, further, the molecular weight of the vinyl polyether macromonomer is 3000-6000; The reducing agent aqueous solution is prepared by dissolving 0.4-0.9 parts of reducing agent in 30 parts of water; the chain transfer agent aqueous solution is prepared by dissolving 0.3-1.0 parts of chain transfer agent in 30 parts of water; and the unsaturated carboxylic acid aqueous solution is prepared by dissolving 10-20 parts of acrylic acid in 30 parts of water.
[0011] On the basis of the above technical solution, further, the chain transfer agent is at least one of mercaptoethanol, thioglycolic acid, mercaptopropionic acid, n-dodecyl mercaptan or tert-dodecyl mercaptan.
[0012] The present invention provides a cement-based material shrinkage-reducing and anti-cracking admixture prepared by using any of the above-mentioned shrinkage-reducing water-reducing agents, which is prepared by blending the shrinkage-reducing water-reducing agent with a densifier, wherein the mass ratio of the shrinkage-reducing water-reducing agent to the densifier is (80-100): (10-30).
[0013] On the basis of the above technical solution, further, the compacting agent is prepared by adding 5 to 10 parts of urea, 10 to 20 parts of potassium dihydrogen phosphate and 50 to 100 parts of water to 10 to 100 parts of rhamnose by weight, and then adding 5 to 10 parts of Pseudomonas aeruginosa, and fermenting at 25 to 40° C. for 3 to 10 days.
[0014] The technical solution of the present invention has the following principles and beneficial effects: The functional monomer provided by the present invention can be used as a synthetic shrinkage-reducing water-reducing agent. By introducing a polyether compound of tetraalkoxysilane, the shrinkage performance of concrete is regulated from multiple dimensions. Specifically, by reducing the surface tension of the concrete pore solution, the capillary negative pressure is effectively reduced. This mechanism directly acts on the internal microstructure of the concrete, reducing the possibility of concrete autogenous shrinkage and drying shrinkage. At the same time, the shrinkage-reducing water-reducing agent provided by the present invention also has the ability to delay the cement hydration process, which not only alleviates the rate of decrease of the relative humidity inside the concrete, but also cleverly increases the supersaturation and crystallization pressure of calcium hydroxide and calcium aluminate by changing the ion concentration of the pore solution, thereby forming an inherent compensatory stress mechanism, which effectively reduces the shrinkage of concrete and provides a solid guarantee for preventing concrete cracking.
[0015] The unique composition and preparation process of the compacting agent of the present invention enable it to significantly improve the rheological properties of fresh concrete slurry, and during the concrete hardening process, effectively optimize the pore structure of the concrete, make the concrete more compact, and reduce concrete shrinkage.
[0016] The cement-based material shrinkage-reducing and anti-cracking admixture of the present invention mixes the above-mentioned shrinkage-reducing water-reducing agent with a densifier, and the two form a good synergistic effect, which can effectively control the shrinkage of concrete, solve the shrinkage cracking problem in concrete engineering, and provide strong technical support for the durability and safety of concrete engineering. It has important practical application value in the field of concrete admixture technology. DETAILED DESCRIPTION
[0017] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0018] The present invention provides the following structural examples of functional monomers, and their structural formulas are as follows: ; Among them, R 1is a hydrocarbon group of 1 to 20 carbon atoms, a is an integer of 1 to 4, b is an integer of 5 to 30, and m is an integer of 0 to 3.
[0019] The present invention also provides the following embodiments of the shrinkage-reducing and anti-cracking admixture for cement-based materials (including the preparation embodiments of the functional monomer and the shrinkage-reducing water-reducing agent): Example 1 Add 3g of tetramethoxysilane, 30g of methyl allyl polyethylene glycol ether (molecular weight 500), 0.03g of p-toluenesulfonic acid, 1g of methanol and 0.3g of water to the flask in the vacuum distillation apparatus, heat to 50°C, react for 2h, continue to heat to 105°C, react for 2h, and remove methanol by vacuum distillation to obtain a functional monomer.
[0020] 10g of functional monomer, 80g of ethylene glycol monovinyl polyglycol ether (molecular weight 3000), 1g of hydrogen peroxide and 50g of water were added to the reactor, the temperature was controlled at 20°C, and then vitamin C aqueous solution, acrylic acid aqueous solution and thioglycolic acid aqueous solution were added dropwise at a uniform speed for 3h. After the addition was completed, the mixture was kept warm for 1h, and a suitable amount of water was added to adjust the concentration of the reaction product to 50%. The pH of the reaction product was adjusted to 6.0-7.0 with sodium hydroxide to obtain a shrinkage-reducing water-reducing agent. The vitamin C aqueous solution is 0.4 g of vitamin C dissolved in 30 g of water, the thioglycolic acid aqueous solution is 0.3 g of thioglycolic acid dissolved in 30 g of water, and the acrylic acid aqueous solution is 10 g of acrylic acid dissolved in 30 g of water.
[0021] 5 g of urea and 10 g of potassium dihydrogen phosphate were added to 100 g of rhamnose, and the mixture was mixed with 50 g of water. 5 g of Pseudomonas aeruginosa was added thereto, and the mixture was fermented at 25° C. for 3 days to obtain a compacting agent.
[0022] 100 g of shrinkage-reducing water-reducing agent and 10 g of densifying agent were mixed to obtain a cement-based material shrinkage-reducing and anti-cracking admixture.
[0023] Example 2 Add 4 g of tetramethoxysilane, 40 g of isopentenyl polyethylene glycol ether (molecular weight 800), 0.04 g of acetic acid, 2 g of methanol and 0.4 g of water to the flask in the vacuum distillation apparatus, heat to 55°C, react for 3 hours, continue to heat to 108°C, react for 3 hours, and remove methanol by vacuum distillation to obtain a functional monomer.
[0024] 20g of functional monomer, 90g of 4-hydroxybutyl vinyl polyethylene glycol ether (molecular weight 5000), 1.2g of hydrogen peroxide and 60g of water were added to the reactor, the temperature was controlled at 25°C, and then the aqueous solution of bleaching powder, the aqueous solution of acrylic acid and the aqueous solution of mercaptopropionic acid were added dropwise at a uniform speed for 3h. After the addition was completed, the mixture was kept warm for 1h, and a suitable amount of water was added to adjust the concentration of the reaction product to 50%. The pH of the reaction product was adjusted to 6.0-7.0 with sodium hydroxide to obtain a shrinkage-reducing water-reducing agent. The aqueous solution of bleaching powder is 0.7 g of bleaching powder dissolved in 30 g of water, the aqueous solution of mercaptopropionic acid is 0.6 g of mercaptopropionic acid dissolved in 30 g of water, and the aqueous solution of acrylic acid is 17 g of acrylic acid dissolved in 30 g of water.
[0025] 8 g of urea and 15 g of potassium dihydrogen phosphate were added to 80 g of rhamnose, mixed with 60 g of water, and then 8 g of Pseudomonas aeruginosa was added. The mixture was fermented at 30° C. for 5 days to obtain a compacting agent.
[0026] 95 g of shrinkage-reducing water-reducing agent and 20 g of densifying agent were mixed to obtain a cement-based material shrinkage-reducing and anti-cracking admixture.
[0027] Example 3 Add 5g of tetramethoxysilane, 60g of methyl allyl polyethylene glycol ether (molecular weight 1000), 0.08g of p-toluenesulfonic acid, 5g of methanol and 0.9g of water to the flask in the vacuum distillation apparatus, heat to 60°C, react for 5h, continue to heat to 115°C, react for 5h, remove methanol by vacuum distillation, and obtain a functional monomer.
[0028] 40g of functional monomer, 100g of ethylene glycol monovinyl polyglycol ether, 2g of hydrogen peroxide and 100g of water were added to a reaction kettle, the temperature was controlled at 20°C, and then vitamin C aqueous solution, acrylic acid aqueous solution and thioglycolic acid aqueous solution were added dropwise at a uniform speed for 3h. After the addition was completed, the temperature was kept for 1h, and a suitable amount of water was added to adjust the concentration of the reaction product to 50%. The pH of the reaction product was adjusted to 6.0-7.0 with sodium hydroxide to obtain a shrinkage-reducing water-reducing agent. The vitamin C aqueous solution is 0.9 g of vitamin C dissolved in 30 g of water, the thioglycolic acid aqueous solution is 1.0 g of thioglycolic acid dissolved in 30 g of water, and the acrylic acid aqueous solution is 20 g of acrylic acid dissolved in 30 g of water. The molecular weight of ethylene glycol monovinyl polyethylene glycol ether is 6,000.
[0029] 10 g of urea and 20 g of potassium dihydrogen phosphate were added to 85 g of rhamnose, and the mixture was mixed with 100 g of water. 10 g of Pseudomonas aeruginosa was added thereto, and the mixture was fermented at 40° C. for 10 days to obtain a compacting agent.
[0030] 100 g of shrinkage-reducing water-reducing agent and 30 g of densifying agent were mixed to obtain a cement-based material shrinkage-reducing and anti-cracking admixture.
[0031] Comparative Example 1 Compared with Example 1, in Comparative Example 1, no functional monomer was introduced in the preparation of the shrinkage-reducing water-reducing agent, and the other conditions were the same as those in Example 1.
[0032] 100 g of shrinkage-reducing water reducer and 10 g of densifier were mixed to obtain cement-based material admixture.
[0033] Comparative Example 2 Compared with Example 1, in Comparative Example 2, no densifier was added, and only the shrinkage-reducing water-reducing agent in Example 1 was used as a cement-based material admixture.
[0034] Comparative Example 3 (Ordinary water reducing agent) Kezhijie New Materials Group Co., Ltd. produces PS polycarboxylate water reducer.
[0035] The cement-based material admixtures prepared in the above examples and comparative examples were subjected to concrete mixture performance tests in accordance with GB / T 50080-2016 "Standard for Test Methods for Performance of Ordinary Concrete Mixtures" and JC / T 2361-2016 "Mortar and Concrete Shrinkage Reducing Agents".
[0036] Concrete mix ratio: cement 360kg / m 3 、Mechanical sand 790kg / m 3 、Stone 1060kg / m 3 , water 162kg / m 3 .
[0037] The performance test results are shown in the following table: Table 1 sample Dosage / % Initial slump / mm 7d reduction rate / % Example 1 0.15 195 38 Example 2 0.15 200 37 Example 3 0.15 205 35 Comparative Example 1 0.15 190 15 Comparative Example 2 0.15 195 22 Comparative Example 3 0.15 190 7 Through the above experimental tests and comparisons, we can know that: Compared with Comparative Example 1, the admixtures prepared in Examples 1 to 3 and applied to concrete can significantly reduce the shrinkage of concrete, mainly because in Examples 1 to 3, the polyether compound of tetraalkoxysilane is introduced into the shrinkage-reducing water-reducing agent by using functional monomers, combined with the compacting agent and other technical features, the capillary negative pressure can be reduced by reducing the surface tension of the concrete pore solution, thereby reducing the autogenous shrinkage and drying shrinkage of the concrete, and by delaying cement hydration and thereby relieving the decrease in internal relative humidity, changing the ion concentration of the pore solution and thereby increasing the supersaturation and crystallization pressure of calcium hydroxide and ettringite, etc., which plays a role in reducing the shrinkage of concrete. Comparative Example 1 uses a water-reducing agent without functional monomers mixed with a compacting agent as an additive for concrete, and the shrinkage reduction performance of the concrete is much lower than that of the admixtures obtained in Examples 1 to 3.
[0038] Compared with Comparative Example 2, the admixtures prepared in Examples 1 to 3 can reduce the shrinkage of concrete when applied to concrete, mainly because the densifiers prepared in Examples 1 to 3 can effectively improve and optimize the rheological properties of fresh concrete paste, thereby improving the pore structure of concrete, making the concrete more compact and reducing concrete shrinkage. Comparative Example 2 does not add a densifier, and the shrinkage reduction performance of concrete is lower than that of the admixtures obtained in Examples 1 to 3.
[0039] Comparative Example 3 is a common water reducing agent, and compared with the example, no functional monomer and compacting agent are added. Compared with Comparative Example 3, the admixtures prepared in Examples 1 to 3 can significantly reduce the shrinkage of concrete when applied to concrete, mainly because the shrinkage-reducing water reducing agent and the compacting agent in the admixtures of Examples 1 to 3 form a good synergistic effect, effectively reducing the shrinkage of concrete.
[0040] The invention successfully prepares a shrinkage-reducing and anti-cracking admixture by blending a shrinkage-reducing water-reducing agent with a functional monomer and a densifier in a specific mass ratio. This innovative combination gives full play to the shrinkage-reducing performance advantages of both, and achieves the superposition and amplification of performance. Compared with the prior art, the admixture of the invention shows more excellent performance in controlling concrete shrinkage, effectively solves the concrete shrinkage cracking problem that has long plagued the engineering community, provides strong technical support for the durability and safety of concrete engineering, and has significant progress and creativity in the field of concrete admixture technology.
[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A functional monomer, characterized in that: The structural formula is as follows: ； Wherein, R1 is a hydrocarbon group of 1 to 20 carbon atoms, a is an integer of 1 to 4, b is an integer of 5 to 30, and m is an integer of 0 to 3.
2. A method for preparing a functional monomer according to claim 1, characterized in that: The method comprises the following steps: adding 3 to 5 parts of tetraalkoxysilane, 30 to 60 parts of unsaturated polyether, 0.03 to 0.08 parts of p-toluenesulfonic acid or acetic acid, 1 to 5 parts of methanol and 0.3 to 0.9 parts of water into a container by weight, heating to 50 to 60° C., reacting for 2 to 5 hours, continuing to heat to 105 to 120° C., reacting for 2 to 5 hours, and removing methanol by reduced pressure distillation to obtain the functional monomer.
3. The method for preparing a functional monomer according to claim 2, characterized in that: The molecular weight of the unsaturated polyether is 500-1000.
4. A shrinkage-reducing water-reducing agent, characterized in that: It is prepared by polymerization reaction of vinyl polyether macromonomer, unsaturated carboxylic acid and functional monomer in the mass ratio of (60-100): (10-20): (10-40) in the presence of water, initiator and chain transfer agent. The structural formula of the functional monomer is as follows: ； Wherein, R1 is a hydrocarbon group of 1 to 20 carbon atoms, a is an integer of 1 to 4, b is an integer of 5 to 30, and m is an integer of 0 to 3.
5. A method for preparing the shrinkage-reducing water-reducing agent according to claim 4, characterized in that: The initiator is a hydrogen peroxide-reducing agent system; The reducing agent is at least one of bisulfite, sulfite, bleaching agent and vitamin C.
6. A method for preparing the shrinkage-reducing water-reducing agent according to claim 5, characterized in that: The following steps are involved: 10-40 parts of functional monomers, 60-100 parts of vinyl polyether macromonomers, 1-2 parts of hydrogen peroxide, and 50-100 parts of water are added to a reaction kettle by weight, the temperature is controlled at 20-25°C, and a reducing agent aqueous solution, an unsaturated carboxylic acid aqueous solution, and a chain transfer agent aqueous solution are added dropwise for 3-4 hours. After the addition is completed, the temperature is kept for 1-2 hours, and water is added to adjust the concentration to obtain a reaction product of 50%; The pH of the reaction product is adjusted to 6.0-7.0 with sodium hydroxide to obtain a shrinkage-reducing water-reducing agent.
7. A method for preparing the shrinkage-reducing water-reducing agent according to claim 6, characterized in that: The molecular weight of the vinyl polyether macromonomer is 3000 to 6000; The reducing agent aqueous solution is prepared by dissolving 0.4 to 0.9 parts of reducing agent in 30 parts of water; The chain transfer agent aqueous solution is prepared by dissolving 0.3 to 1.0 parts of chain transfer agent in 30 parts of water; The unsaturated carboxylic acid aqueous solution is prepared by dissolving 10 to 20 parts of acrylic acid in 30 parts of water.
8. A method for preparing the shrinkage-reducing water-reducing agent according to claim 4, characterized in that: The chain transfer agent is at least one of mercaptoethanol, thioglycolic acid, mercaptopropionic acid, n-dodecyl mercaptan or tert-dodecyl mercaptan.
9. A shrinkage-reducing and anti-cracking admixture for cement-based materials prepared by using the shrinkage-reducing water-reducing agent according to any one of claims 4 to 8, characterized in that: The shrinkage-reducing water-reducing agent is mixed with a densifier, wherein the mass ratio of the shrinkage-reducing water-reducing agent to the densifier is (80-100): (10-30).
10. The shrinkage-reducing and anti-cracking admixture for cement-based materials according to claim 9, characterized in that: The densifying agent is prepared by adding 5 to 10 parts of urea, 10 to 20 parts of potassium dihydrogen phosphate and 50 to 100 parts of water to 10 to 100 parts of rhamnose, and then adding 5 to 10 parts of Pseudomonas aeruginosa, and fermenting at 25 to 40° C. for 3 to 10 days.