Anti-dispersing agent for underwater non-dispersible concrete and preparation method of anti-dispersing agent

Abstract

The invention discloses an anti-dispersing agent for underwater non-dispersible concrete and a preparation method thereof, and belongs to the technical field of concrete admixtures, the preparation method comprises the following steps: mixing acrylic acid, 2-acrylamido-2-sodium methylpropanesulfonate, a cross-linking agent, sodium hydroxide and a modified isopentenyl polyoxyethylene ether solution, and heating to raise the temperature; adding ammonium persulfate and ascorbic acid, stirring, adding hydroquinone, and continuously stirring, so as to obtain the anti-dispersing agent for underwater non-dispersible concrete. When the anti-dispersing agent provided by the invention is used in underwater non-dispersible concrete, the concrete has the effects of dispersion resistance and flowability, good flowing water scouring resistance, high water-land strength ratio and greatly shortened setting time compared with a conventional anti-dispersing agent.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete admixtures, and in particular relates to an anti-dispersant for underwater non-dispersible concrete and a preparation method thereof. Background Art

[0002] Underwater concrete is widely used in the construction of underwater structures such as dams, marine engineering projects, bridge foundations, and docks. Its key features are its ability to resist erosion and harden underwater, maintaining excellent strength and durability. The addition of admixtures such as anti-dispersants can effectively prevent problems such as loss of concrete strength and structural unevenness caused by water dispersion, thereby ensuring construction quality and structural safety. Underwater concrete anti-dispersants are crucial admixtures for improving the construction performance of underwater concrete. Their development aims to reduce the dispersion of concrete in water and improve its stability and durability.

[0003] In the prior art, patent CN114316131A proposes a polyacrylamide for underwater non-dispersible concrete, its preparation method, and concrete. The terpolymer is prepared by copolymerizing acrylamide, acrylic acid, and allyl-AD galactopyranoside. Wang Ying et al. (CN110054434 A) formulated a flocculant for underwater non-dispersible concrete by mixing grafted modified konjac flour, polyethylene glycol dilaurate, a dispersant, sodium nitrilotriacetic acid, lithium polystyrene sulfonate, and wollastonite in a proportional manner. The freshly mixed concrete with the flocculant exhibits good viscosity and fluidity, and exhibits self-leveling and self-compacting properties after being poured underwater. Lin Xian et al. (CN1191287C) produced acrylamide-polyvinyl alcohol copolymers by bubbling nitrogen through acrylamide monomer and polyvinyl alcohol, followed by the addition of hydrogen peroxide, ferrous sulfate, or ceric ammonium nitrate. Alternatively, a modified polyacrylamide flocculant was prepared by mixing naphthalenesulfonic acid formaldehyde condensate with the copolymer. Zhao Yan et al., in patent CN108203256A, disclosed a flocculant for high-strength underwater, non-dispersible concrete. Compared to concrete without this flocculant, the concrete produced by mixing and adding this flocculant in a suitable proportion exhibits a shorter setting time, no water segregation, no underwater dispersion, and higher strength. The above-mentioned prior art anti-dispersants / flocculants are primarily prepared by modifying acrylamide. The resulting product has reduced fluidity after increasing cohesiveness, and the impact of dynamic water erosion on underwater, non-dispersible concrete under actual working conditions has not been studied.

[0004] Therefore, how to provide an anti-dispersant for underwater non-dispersible concrete with good comprehensive performance is a technical problem that those skilled in the art urgently need to solve. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides an anti-dispersant for underwater non-dispersible concrete and a preparation method thereof.

[0006] To achieve the above objectives, the present invention provides the following technical solutions:

[0007] An anti-dispersant for underwater non-dispersible concrete, the structural formula of which is shown in formula (I):

[0008]

[0009] (I);

[0010] Wherein, R1 is independently selected from 、 、 、 ;

[0011] R2 is independently selected from 、 ;

[0012] m=200~500;

[0013] n=15~70.

[0014] Beneficial Effects: The anti-dispersant provided by the present invention is a polymer with a micro-crosslinked structure (i.e., a polymeric structure containing R2 in Formula I), which enhances its coating effect on cement slurry. The benzene ring groups increase the rigidity of the structure itself, enhancing the cohesiveness of the concrete while also improving its anti-scouring effect under dynamic water impact. The long side chain isopentenyl polyoxyethylene ether can form hydrogen bonds with water molecules, playing a certain role in water retention and wetting, reducing the yield stress of concrete, improving concrete thixotropy, and enhancing fluidity. Furthermore, the sulfonic acid groups contained in the sodium 2-acrylamido-2-methylpropanesulfonate in the structure have strong polarization ability towards water molecules, improving the overall salt tolerance of the structure and enhancing the adaptability of the anti-dispersant in different water environments. Underwater non-dispersible concrete doped with this anti-dispersant can achieve both anti-dispersibility and fluidity, with excellent resistance to dynamic water scouring, a high water-to-land strength ratio, and a significantly shorter setting time than conventional anti-dispersants.

[0015] A method for preparing an anti-dispersant for underwater non-dispersible concrete comprises the following steps:

[0016] Acrylic acid, sodium 2-acrylamido-2-methylpropanesulfonate, a cross-linking agent, sodium hydroxide and a modified isopentenyl polyoxyethylene ether solution are mixed and heated to a high temperature, and then ammonium persulfate and ascorbic acid are added. After stirring, hydroquinone is added and stirring is continued to obtain the anti-dispersant for underwater non-dispersible concrete.

[0017] Preferably, the cross-linking agent is one of dimethyldiallylammonium chloride and diethyl diallylmalonate.

[0018] Preferably, the preparation method of the modified isopentenyl polyoxyethylene ether solution comprises the following steps:

[0019] After the isopentenyl polyoxyethylene ether is melted, monoisocyanate is added, the mixture is heated for reaction, cooled, and then water is added and mixed evenly to obtain the modified isopentenyl polyoxyethylene ether solution.

[0020] Preferably, the molecular weight of the isopentenyl polyoxyethylene ether is 800 g / mol, 1200 g / mol, 2400 g / mol or 3000 g / mol.

[0021] More preferably, the molecular weight of the isopentenyl polyoxyethylene ether is 2400 g / mol.

[0022] Preferably, the monoisocyanate includes one of phenyl isocyanate, benzyl isocyanate, p-methylphenyl isocyanate, and p-nitrophenyl isocyanate.

[0023] Preferably, the heating temperature is 60°C.

[0024] Preferably, the stirring treatment is: stirring continuously for 0.5 h, then standing for 5 min, and then stirring for 20 min.

[0025] Preferably, the stirring time is 5 minutes.

[0026] The above-mentioned anti-dispersant for underwater non-dispersible concrete is used as the anti-dispersant; the amount of the anti-dispersant in the concrete raw material is 1.5~3.5kg / m 3 .

[0027] Compared with the prior art, the present invention has the following advantages and technical effects:

[0028] The anti-dispersant provided by the present invention has many advantages: first, the micro-crosslinking structure is introduced into the structure, which enhances its coating effect on cement slurry, and the benzene ring group increases the rigidity of the structure itself, thereby enhancing the cohesiveness of the concrete and improving its anti-scouring effect under dynamic water impact; the long side chain isopentenyl polyoxyethylene ether can form hydrogen bonds with water molecules, play a certain water-retaining and wetting role, reduce the yield stress of concrete, improve the thixotropy of concrete, and enhance fluidity. In addition, the sulfonic acid group contained in the 2-acrylamido-2-methylpropanesulfonic acid sodium in the structure has a strong polarization ability for water molecules, improves the overall tolerance of the structure to salt, and enhances the adaptability of the anti-dispersant in different water environments. In addition, the raw materials used in the anti-dispersant are simple and easy to obtain, there is no volatile solvent in the preparation process, the main reaction is carried out in an aqueous solution, no waste liquid and waste gas are discharged, and no purification and separation are required. The production process meets the requirements of green environmental protection, and compared with traditional polyacrylamide-cellulose ether and polysaccharide anti-dispersants, the product has a shorter setting time and higher early strength. DETAILED DESCRIPTION

[0029] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with specific embodiments.

[0031] Unless otherwise specified, the raw materials in the examples of the present invention were purchased from commercial sources.

[0032] Unless otherwise specified, room temperature or normal temperature in the embodiments of the present invention refers to 25±3°C.

[0033] Example 1

[0034] A method for preparing an anti-dispersant for underwater non-dispersible concrete comprises the following steps:

[0035] (1) Take 0.1 mol of isopentyl polyoxyethylene ether with a molecular weight of 1200 g / mol, heat it at 80°C until it is molten, then add 0.1 mol of phenyl isocyanate, keep stirring at 80°C for 3 hours, cool it to 25°C, and add 4000 g of deionized water to obtain modified isopentyl polyoxyethylene ether solution W1. The structural formula of modified isopentyl polyoxyethylene ether is as follows:

[0036] ;

[0037] (2) To the W1 obtained in step (1), 0.05 mol of acrylic acid, 0.4 mol of sodium 2-acrylamido-2-methylpropanesulfonate, 0.1 g of a 60% mass fraction dimethyldiallyl ammonium chloride solution, and 0.04 mol of sodium hydroxide were added in sequence, stirred evenly, and then heated to 60°C. 0.1 g of ammonium persulfate and 0.02 g of ascorbic acid were then added in sequence. The mixture was stirred for 0.5 h and allowed to stand for 5 min. After stirring for 20 min, 0.01 g of hydroquinone was added and the mixture was stirred for 5 min to obtain an anti-dispersant. The structure is shown below:

[0038]

[0039] Example 2

[0040] A method for preparing an anti-dispersant for underwater non-dispersible concrete comprises the following steps:

[0041] (1) Take 0.1 mol of isopentyl polyoxyethylene ether with a molecular weight of 2400 g / mol, heat it at 80°C until it is molten, then add 0.1 mol of benzyl isocyanate, keep stirring at 80°C for 3 hours, cool it to 25°C, and add 4000 g of deionized water to obtain modified isopentyl polyoxyethylene ether solution W2. The structural formula of the modified isopentyl polyoxyethylene ether is as follows:

[0042] ;

[0043] (2) To the W2 obtained in step (1), 0.05 mol of acrylic acid, 0.4 mol of sodium 2-acrylamido-2-methylpropanesulfonate, 0.1 g of a 60% mass fraction dimethyldiallyl ammonium chloride solution, and 0.04 mol of sodium hydroxide were added in sequence, stirred evenly, and then heated to 60°C. 0.1 g of ammonium persulfate and 0.02 g of ascorbic acid were then added in sequence. The mixture was stirred for 0.5 h and allowed to stand for 5 min. After stirring for 20 min, 0.01 g of hydroquinone was added and the mixture was stirred for 5 min to obtain an anti-dispersant. The structure is shown below:

[0044]

[0045] Example 3

[0046] A method for preparing an anti-dispersant for underwater non-dispersible concrete comprises the following steps:

[0047] (1) 0.1 mol of isopentyl polyoxyethylene ether with a molecular weight of 2400 g / mol was heated at 80°C until it melted, and then 0.1 mol of p-methylphenyl isocyanate was added. The temperature was maintained at 80°C and stirred for 3 hours, then cooled to 25°C and 4000 g of deionized water was added to obtain a modified isopentyl polyoxyethylene ether solution W3. The structural formula of the modified isopentyl polyoxyethylene ether is shown below:

[0048] ;

[0049] (2) To the W3 obtained in step (1), 0.05 mol of acrylic acid, 0.4 mol of sodium 2-acrylamido-2-methylpropanesulfonate, 0.1 g of a 60% mass fraction dimethyldiallyl ammonium chloride solution, and 0.04 mol of sodium hydroxide were added in sequence, stirred evenly, and then heated to 60°C. 0.1 g of ammonium persulfate and 0.02 g of ascorbic acid were then added in sequence. The mixture was stirred for 0.5 h and allowed to stand for 5 min. After stirring for 20 min, 0.01 g of hydroquinone was added and the mixture was stirred for 5 min to obtain an anti-dispersant. The structure is shown below:

[0050]

[0051] Example 4

[0052] A method for preparing an anti-dispersant for underwater non-dispersible concrete comprises the following steps:

[0053] (1) Take 0.1 mol of isopentyl polyoxyethylene ether with a molecular weight of 2400 g / mol, heat it at 80°C until it is molten, then add 0.1 mol of p-nitrophenyl isocyanate, keep stirring at 80°C for 3 hours, cool it to 25°C, and add 4000 g of deionized water to obtain modified isopentyl polyoxyethylene ether solution W4. The structural formula of the modified isopentyl polyoxyethylene ether is as follows:

[0054] ;

[0055] (2) To the W4 obtained in step (1), 0.05 mol of acrylic acid, 0.4 mol of sodium 2-acrylamido-2-methylpropanesulfonate, 0.1 g of a 60% mass fraction dimethyldiallylammonium chloride solution, and 0.04 mol of sodium hydroxide were added in sequence, stirred evenly, and then heated to 60°C. 0.1 g of ammonium persulfate and 0.02 g of ascorbic acid were then added in sequence. The mixture was stirred for 0.5 h and allowed to stand for 5 min. After stirring for 20 min, 0.01 g of hydroquinone was added and the mixture was stirred for 5 min to obtain an anti-dispersant. The structure is shown below:

[0056]

[0057] Comparative Example 1

[0058] A method for preparing an anti-dispersant comprises the following steps:

[0059] (1) 0.1 mol of isopentyl polyoxyethylene ether having a molecular weight of 1200 g / mol was added to 4000 g of deionized water to obtain isopentyl polyoxyethylene ether solution A1;

[0060] (2) To A1, 0.05 mol of acrylic acid, 0.4 mol of sodium 2-acrylamido-2-methylpropanesulfonate, 0.1 g of 60% dimethyldiallylammonium chloride solution, and 0.04 mol of sodium hydroxide were added in sequence. After stirring evenly, the temperature was raised to 60°C. 0.1 g of ammonium persulfate and 0.02 g of ascorbic acid were then added in sequence. The mixture was stirred for 0.5 h and allowed to stand for 5 min. After stirring for 20 min, 0.01 g of hydroquinone was added. The mixture was stirred for 5 min to obtain an anti-dispersant. The structure is shown below:

[0061]

[0062] Comparative Example 2

[0063] A method for preparing an anti-dispersant for underwater non-dispersible concrete comprises the following steps:

[0064] (1) Take 0.1 mol of isopentyl polyoxyethylene ether with a molecular weight of 2400 g / mol, heat it at 80°C until it is molten, then add 0.1 mol of benzyl isocyanate, keep stirring at 80°C for 3 hours, cool it to 25°C, and add 4000 g of deionized water to obtain modified isopentyl polyoxyethylene ether solution A2. The structural formula of the modified isopentyl polyoxyethylene ether is as follows:

[0065] ;

[0066] (2) To A2 obtained in step (1), 0.05 mol of acrylic acid, 0.1 g of a 60% mass fraction dimethyldiallyl ammonium chloride solution, and 0.04 mol of sodium hydroxide were added in sequence, stirred evenly, and then heated to 60°C. 0.1 g of ammonium persulfate and 0.02 g of ascorbic acid were then added in sequence. The mixture was stirred for 0.5 h and allowed to stand for 5 min. After stirring for 20 min, 0.01 g of hydroquinone was added and the mixture was stirred for 5 min to obtain an anti-dispersant. The structure of the anti-dispersant is shown below:

[0067]

[0068] Comparative Example 3

[0069] A method for preparing an anti-dispersant for underwater non-dispersible concrete comprises the following steps:

[0070] (1) 0.1 mol of isopentyl polyoxyethylene ether with a molecular weight of 2400 g / mol was heated at 80°C until it melted, and then 0.1 mol of p-methylphenyl isocyanate was added. The temperature was maintained at 80°C and stirred for 3 hours, then cooled to 25°C and 4000 g of deionized water was added to obtain a modified isopentyl polyoxyethylene ether solution A3. The structural formula of the modified isopentyl polyoxyethylene ether is shown below:

[0071] ;

[0072] (2) To A3 obtained in step (1), 0.05 mol of acrylic acid, 0.4 mol of acrylamide, 0.1 g of a 60% by mass dimethyldiallyl ammonium chloride solution, and 0.04 mol of sodium hydroxide were added in sequence, stirred evenly, and then heated to 60°C. 0.1 g of ammonium persulfate and 0.02 g of ascorbic acid were then added in sequence. The mixture was stirred for 0.5 h and allowed to stand for 5 min. After stirring for 20 min, 0.01 g of hydroquinone was added and the mixture was stirred for 5 min to obtain an anti-dispersant. The structure of the anti-dispersant is shown below:

[0073]

[0074] Comparative Example 4

[0075] A method for preparing an anti-dispersant for underwater non-dispersible concrete comprises the following steps:

[0076] (1) 0.1 mol of isopentyl polyoxyethylene ether with a molecular weight of 2400 g / mol was heated at 80°C until it melted, and then 0.1 mol of p-nitrophenyl isocyanate was added. The mixture was stirred at 80°C for 3 hours, then cooled to 25°C and 4000 g of deionized water was added to obtain a modified isopentyl polyoxyethylene ether solution A4. The structural formula of the modified isopentyl polyoxyethylene ether is shown below:

[0077] ;

[0078] (2) To A4 obtained in step (1), 0.05 mol of acrylic acid, 0.4 mol of sodium 2-acrylamido-2-methylpropanesulfonate and 0.02 mol of sodium hydroxide were added in sequence, stirred evenly and then heated to 60°C. 0.1 g of ammonium persulfate and 0.02 g of ascorbic acid were then added in sequence. The mixture was stirred for 0.5 h and allowed to stand for 5 min. After stirring for 20 min, 0.01 g of hydroquinone was added and the mixture was stirred for 5 min to obtain an anti-dispersant. The structure of the anti-dispersant is shown below:

[0079]

[0080] Technical effect:

[0081] The underwater non-dispersible concrete anti-dispersant prepared in the examples and comparative examples was added to the C40 concrete in a solid content of 0.05% of the cementitious mass. The mix ratio of the C40 concrete (kg / m 3 )for:

[0082] Water-cement ratio 0.38, cement 306kg / m 3 、FA97kg / m 3 , sand 802kg / m 3 , G 5-10 631kg / m 3 , G 10-20 431kg / m 3 、Water 153kg / m 3 , polycarboxylate water reducer 1wt%, anti-dispersant 2.6kg / m 3 .

[0083] A blank group (no anti-dispersant added) and a control group (the anti-dispersant was replaced with the mainstream polysaccharide UWB-Π anti-dispersant on the market, with the dosage being 10% of the gelling material) were also set up.

[0084] The test methods refer to GBT37990-2019 "Technical Requirements for Underwater Non-Dispersible Concrete Flocculants" and DL / T5117-2021 "Test Procedures for Underwater Non-Dispersible Concrete." The test indicators are suspended matter content, setting time, and water-to-land strength ratio. The anti-scour performance of underwater non-dispersible concrete was also tested with reference to the CRD-C61-89A (1989) standard test method. The results are shown in Table 1:

[0085] Table 1 Test data of underwater non-dispersible concrete

[0086]

[0087] Note: The test of a was carried out in 20% sodium chloride solution

[0088] As shown in Table 1, the use of the anti-dispersant obtained in Examples 1-4 to prepare concrete significantly reduces the suspended matter content compared to the blank group, indicating that it has good anti-dispersibility under static water conditions, while the scouring weight loss is less than that of the control group, and the 1h expansion is higher than that of the concrete mixed with UWB-II, indicating that it has better anti-dispersibility under dynamic water action, and maintains good workability while increasing cohesion. Among them, the technical effect of preparing concrete using the anti-dispersant prepared in Example 3 is the best. Compared with Example 1, Comparative Example 1 does not introduce a benzene ring group, and its rigidity is slightly poor, so its anti-dynamic water performance is poor; Comparative Example 2 lacks 2-acrylamido-2-methylpropanesulfonic acid sodium, and the overall cohesion decreases, and the anti-dispersibility weakens; Compared with Example 3, 2-acrylamido-2-methylpropanesulfonic acid sodium is replaced by acrylamide in Comparative Example 3, and there is no significant change in performance in aqueous solution, and the difference is reflected in the test in high salt concentration water; Compared with Example 4, Comparative Example 4 does not add a cross-linking agent, and basically loses the anti-dispersibility effect.

[0089] The above are merely preferred embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. An anti-dispersion agent for underwater non-dispersible concrete, characterized in that: The structural formula is shown in formula (I): （I）； Wherein, R1 is independently selected from 、 、 、 ; R2 is independently selected from 、 ; m=200~500； n=15~70。 2. The method for preparing an anti-dispersant for underwater non-dispersible concrete according to claim 1, wherein: The following steps are involved: Acrylic acid, sodium 2-acrylamido-2-methylpropanesulfonate, a cross-linking agent, sodium hydroxide and a modified isopentenyl polyoxyethylene ether solution are mixed and heated to a high temperature, and then ammonium persulfate and ascorbic acid are added. After stirring, hydroquinone is added and stirring is continued to obtain the anti-dispersant for underwater non-dispersible concrete.

3. The method for preparing an anti-dispersant for underwater non-dispersible concrete according to claim 2, characterized in that: The cross-linking agent is selected from one of dimethyldiallylammonium chloride and diethyl diallylmalonate.

4. The method for preparing an anti-dispersant for underwater non-dispersible concrete according to claim 2, characterized in that: The preparation method of the modified isopentenyl polyoxyethylene ether solution comprises the following steps: After the isopentenyl polyoxyethylene ether is melted, monoisocyanate is added, the mixture is heated for reaction, cooled, and then water is added and mixed evenly to obtain the modified isopentenyl polyoxyethylene ether solution.

5. The method for preparing an anti-dispersant for underwater non-dispersible concrete according to claim 4, characterized in that: The molecular weight of the isopentenyl polyoxyethylene ether is 800 g / mol, 1200 g / mol, 2400 g / mol or 3000 g / mol.

6. The method for preparing an anti-dispersion agent for underwater non-dispersible concrete according to claim 4, characterized in that: The monoisocyanate is selected from one of phenyl isocyanate, benzyl isocyanate, p-methylphenyl isocyanate and p-nitrophenyl isocyanate.

7. The method for preparing an anti-dispersant for underwater non-dispersible concrete according to claim 2, characterized in that: The heating temperature is 60°C.

8. The method for preparing an anti-dispersion agent for underwater non-dispersible concrete according to claim 2, characterized in that: The stirring treatment is as follows: stirring continuously for 0.5 h, then standing for 5 min, and then stirring for 20 min.

9. The method for preparing an anti-dispersant for underwater non-dispersible concrete according to claim 2, characterized in that: The stirring time is continued for 5 minutes.

10. An underwater non-dispersible concrete, characterized in that: The anti-dispersant for underwater non-dispersible concrete according to claim 1 is used as the anti-dispersant; the amount of the anti-dispersant in the concrete raw material is 1.5-3.5 kg / m 3 .

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