CN111961166A - Modified concrete admixture and preparation method and application thereof - Google Patents
Modified concrete admixture and preparation method and application thereof Download PDFInfo
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- CN111961166A CN111961166A CN202010868372.1A CN202010868372A CN111961166A CN 111961166 A CN111961166 A CN 111961166A CN 202010868372 A CN202010868372 A CN 202010868372A CN 111961166 A CN111961166 A CN 111961166A
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F283/00—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G
- C08F283/06—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G on to polyethers, polyoxymethylenes or polyacetals
- C08F283/065—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G on to polyethers, polyoxymethylenes or polyacetals on to unsaturated polyethers, polyoxymethylenes or polyacetals
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
- C04B24/24—Macromolecular compounds
- C04B24/26—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- C04B24/2688—Copolymers containing at least three different monomers
- C04B24/2694—Copolymers containing at least three different monomers containing polyether side chains
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
- C04B2103/30—Water reducers, plasticisers, air-entrainers, flow improvers
- C04B2103/302—Water reducers
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Abstract
The invention provides a modified concrete admixture and a preparation method and application thereof, wherein the modified concrete admixture comprises a modified polycarboxylic acid water reducing agent, and the polycarboxylic acid water reducing agent is formed by polymerizing an unsaturated carboxylic acid monomer, a polyether macromonomer and a hydrophobic monomer in a molar ratio of 4-6: 1: 0.2-0.3; wherein the unsaturated carboxylic acid monomer is acrylic acid and/or methacrylic acid; the structural formula of the polyether macromonomer is shown as formula I, wherein R in the formula I1、R2、R3And R4Each independently is H or CH3B is an integer of 20 to 120; the hydrophobic monomer has the structural formulaFormula II, wherein R is5Is H or CH3，R6Is alkyl with carbon chain length of C8-C12. The polycarboxylate superplasticizer disclosed by the invention has the advantages of improved water reducing rate and good workability.
Description
Technical Field
The invention belongs to the technical field of additives for mortar and concrete, and particularly relates to modification of a polycarboxylate superplasticizer, and a preparation method and application thereof.
Background
In the preparation process of the concrete, a small amount of additive is added, so that the performance of the concrete can be improved, and the water consumption of the concrete can be reduced. Saving cement, reducing cost and improving construction performance. The concrete admixture comprises a water reducing agent, an air entraining agent, a pumping aid, a retarder, an early strength agent, an accelerator and the like, in particular to the water reducing agent.
The polycarboxylate superplasticizer has the advantages of low consumption, high water reducing rate, good slump retention, adjustable molecular structure and the like, provides powerful guarantee for the quality of large-scale engineering, and is an important product in the current concrete admixture market.
The superior performance of the polycarboxylate superplasticizer is derived from the unique molecular structure. The polycarboxylate water reducing agent is a water-soluble comb-shaped polymer, and consists of a main chain rich in carboxylic acid groups and polyoxyethylene ether (hereinafter referred to as polyether) side chains, the carboxylic acid groups on the main chain can be directionally adsorbed on the surface of positively charged cement or cement hydrate, and the polyether side chains extend in a solution to form a water film layer, so that a spatial repulsive force can be provided, and further, the cement agglomeration is prevented. The magnitude of the spatial repulsive force provided by the water film layer is a key factor influencing the water reducing capacity of the local carboxylic acid water reducing agent.
Chinese patent application CN108249807A discloses a novel polycarboxylate water reducing agent, which changes the polyether side chain from traditional linear structure to comb structure to increase the thickness of water film layer, improves the spatial repulsion force, and further improves the water reducing capability of polycarboxylate water reducing agent. However, such polyether side chains have a complex structure, are difficult to synthesize by a one-step method, and have a complex production process and high cost.
Disclosure of Invention
In view of the above, the present invention aims to provide a modified concrete admixture, a preparation method and applications thereof, wherein the concrete admixture comprises a modified polycarboxylic acid water reducing agent, and the modified concrete admixture has improved water reducing rate and good workability.
The purpose of the invention is realized by the following technical scheme.
On one hand, the invention provides a concrete admixture which comprises a modified polycarboxylic acid water reducing agent, wherein the polycarboxylic acid water reducing agent is formed by polymerizing an unsaturated carboxylic acid monomer, a polyether macromonomer and a hydrophobic monomer in a molar ratio of 4-6: 1: 0.2-0.3;
wherein the unsaturated carboxylic acid monomer is acrylic acid and/or methacrylic acid;
the structural formula of the polyether macromonomer is shown as formula I:
in the formula I, R1、R2、R3And R4Each independently is H or CH3B is an integer of 20 to 120;
the structural formula of the hydrophobic monomer is shown as formula II:
in the formula II, R5Is H or CH3，R6Is C8-C12 alkyl.
After the polycarboxylate superplasticizer is anchored on cement particles, a hydrophilic polyether side chain extends in a liquid phase to form a water film layer, and the steric effect of the water film layer is an important factor influencing the water reducing capacity of the polycarboxylate superplasticizer. The inventor of the application finds that the water reducing rate of the polycarboxylic acid water reducing agent can be effectively improved and the workability (slump) is good by introducing the hydrophobic monomer with the C8-C12 alkyl into the main chain.
Without wishing to be limited by theory, it is believed that the comb-shaped molecular structure with the polyether side chain is formed by free radical polymerization of the unsaturated carboxylic acid monomer, the polyether macromonomer and the hydrophobic monomer, and the flexible hydrophobic alkyl structure of the hydrophobic monomer is beneficial to extension of the polyether side chain due to hydrophobicity and steric hindrance effect, so that the thickness of the water film layer is increased, and the water reducing capacity is further improved.
The polycarboxylate superplasticizer provided by the invention has a weight-average molecular weight of 20000-100000 g/mol, preferably 40000-60000 g/mol.
The polycarboxylate superplasticizer provided by the invention comprises the following components in percentage by weight, wherein the components are as follows: allyl polyoxyethylene ether, methyl allyl polyoxyethylene ether and prenol polyoxyethylene ether.
According to the polycarboxylate superplasticizer provided by the invention, in the polyether macromonomer shown in the formula I, b is an integer of 20-120. When the molecular weight of the polyether macromonomer is too small, a sufficient steric hindrance effect cannot be provided, and on the contrary, when the molecular weight is too large, the polyether monomer is low in activity.
In some preferred embodiments, in the polyether macromonomer of formula I, b is an integer of 40 to 100, and in some preferred embodiments, 40 to 70.
According to the polycarboxylate superplasticizer provided by the invention, in the hydrophobic monomer shown in the formula II, R6 can be a straight-chain alkyl group or a branched-chain alkyl group. It is believed that straight chain alkyl groups are more favorable for the polyether side chains to form a water film layer.
Specific examples of hydrophobic monomers suitable for use in the present invention include, but are not limited to: first hydrophobic monomers such as n-octyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, and lauryl (meth) acrylate; and a second hydrophobic monomer such as 4-t-butylcyclohexyl (meth) acrylate, 1-ethylcyclohexyl (meth) acrylate, and isobornyl (meth) acrylate.
In a preferred embodiment of the present invention, the hydrophobic monomers include a first hydrophobic monomer and a second hydrophobic monomer, and the molar ratio of the first hydrophobic monomer to the second hydrophobic monomer is 1:0.2 to 0.5. The inventors have found that the use of such hydrophobic monomers is advantageous for further improving the net paste flow and slump.
On the other hand, the invention also provides a preparation method of the polycarboxylate superplasticizer, wherein the preparation method comprises the following steps:
(1) adding a polyether macromonomer, a hydrophobic monomer and water into a reaction container, and stirring and mixing to obtain a reaction solution;
(2) and (2) dropwise adding an unsaturated carboxylic acid monomer into the step (1) at the temperature of 60-90 ℃ in the presence of an initiator, and continuing to react after the dropwise adding is finished to obtain the polycarboxylic acid water reducing agent.
In the invention, because the polyether macromonomer has higher molecular weight, low double bond content, relatively lower polymerization activity and poor water solubility of the hydrophobic monomer, the polyether macromonomer and the hydrophobic monomer are added into a reaction vessel at one time before polymerization and are fully stirred and mixed, which is beneficial to uniform dispersion of materials and improvement of conversion rate in the polymerization process.
According to the preparation method provided by the invention, the amount of water used in the step (1) can be adjusted according to the polymerization concentration. In some embodiments, the amount of water used in step (1) is 3 to 9 times, and in some embodiments 4 to 6 times, the total mass of the unsaturated carboxylic acid monomer, polyether macromonomer and hydrophobic monomer.
The preparation method provided by the invention, wherein examples of the initiator suitable for the invention include but are not limited to: ammonium persulfate, sodium persulfate, and potassium persulfate.
The preparation method provided by the invention is characterized in that the amount of the initiator in the step (2) is 0.1-1% of the total mass of the unsaturated carboxylic acid monomer, the polyether macromonomer and the hydrophobic monomer.
According to the preparation method provided by the invention, the initiator in the step (2) can be added into the unsaturated carboxylic acid monomer, or can be prepared into an initiator aqueous solution, and the initiator aqueous solution and the unsaturated carboxylic acid monomer are respectively added into the reaction liquid obtained in the step (1) dropwise.
According to the preparation method provided by the invention, the unsaturated carboxylic acid monomer in the step (2) is added for 2-3 hours, and the reaction is continued for 1-5 hours after the dropwise addition is finished.
When the initiator is added dropwise in the form of an aqueous solution in the step (2), the addition time of the initiator can be the same as that of the unsaturated carboxylic acid monomer, and can also be prolonged by 15-30 minutes.
According to the preparation method provided by the invention, the step (2) is carried out under an inert atmosphere. The inert atmosphere is nitrogen atmosphere, helium atmosphere or argon atmosphere.
In still another aspect, the invention provides the use of the modified concrete admixture in concrete.
The application of the modified concrete admixture in concrete provided by the invention is characterized in that the mixing amount of the polycarboxylic acid water reducing agent is 0.1-0.5% of the total gelled material weight in the concrete. In addition, air entraining agents, pumping aids, retarders, early strength agents, thickeners, defoamers, accelerators and the like known in the art may also be included in the concrete admixture.
The polycarboxylic acid water reducing agent of the present invention may be used alone, or may be used in combination with other water reducing agents commercially available, such as lignosulfonate water reducing agents, naphthalene sulfonate water reducing agents, polycarboxylic acid water reducing agents, and the like.
The invention has the following advantages:
(1) the polycarboxylate superplasticizer disclosed by the invention is high in water reducing rate and good in workability, and can be widely applied to the field of concrete.
(2) The polycarboxylic acid water reducing agent disclosed by the invention is simple and convenient in preparation process, low in production cost and beneficial to popularization and application.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
Polycarboxylic acid water reducer weight average molecular weight
The determination was carried out by miniDAWN Tristar aqueous gel permeation chromatograph (GPC, Huanya stunt Co., Ltd.) equipped with TSK-GELSW (Tosoh Biotech Co., Ltd.) column, and the mobile phase was 0.1M NaNO3The flow rate of the aqueous solution is 1.0ml/min, and the mass percent concentration of the sample is 0.5%.
The raw materials and parameters used in the examples of the present invention are shown in table 1.
TABLE 1 raw materials and their parameters
Example 1
(1) 10g (0.01mol) of polyether macromonomer B1 and 0.4g (0.002mol) of hydrophobic monomer C11 were charged into a reaction vessel, 53g of water was added thereto, and the reaction solution was stirred to be purged with nitrogen.
(2) 0.08g of potassium persulfate was dissolved in 2.88g (0.04mol) of the unsaturated carboxylic acid monomer A1, and the solution was added dropwise to the reaction solution obtained in step (1) under nitrogen atmosphere at 80 ℃ under stirring over 3 hours, and the reaction was continued for 3 hours after completion of the addition.
The weight average molecular weight of the prepared polycarboxylate superplasticizer is 42500 g/mol.
Example 2
(1) 20g (0.01mol) of polyether macromonomer B2 and 0.42g (0.002mol) of hydrophobic monomer C12 were charged into a reaction vessel, 93.2g of water was added thereto, and stirred to form a reaction solution, and nitrogen gas was introduced to expel air.
(2) 0.14g of potassium persulfate was dissolved in 2.88g (0.04mol) of the unsaturated carboxylic acid monomer A1, and the solution was added dropwise to the reaction solution obtained in step (1) under nitrogen atmosphere at 80 ℃ under stirring over 3 hours, and the reaction was continued for 3 hours after the completion of the addition.
The weight average molecular weight of the prepared polycarboxylate superplasticizer is 48750 g/mol.
Example 3
(1) 30g (0.01mol) of polyether macromonomer B3 and 0.48g (0.002mol) of hydrophobic monomer C13 were charged into a reaction vessel, 133.4g of water was added thereto, and stirred to form a reaction solution, and nitrogen gas was introduced to discharge air.
(2) 0.2g of potassium persulfate was dissolved in 2.88g (0.04mol) of the unsaturated carboxylic acid monomer A1, and the solution was added dropwise to the reaction solution obtained in step (1) under nitrogen atmosphere at 80 ℃ under stirring over 3 hours, and the reaction was continued for 3 hours after the completion of the addition.
The weight average molecular weight of the prepared polycarboxylate superplasticizer is 52600 g/mol.
Example 4
(1) 40g (0.01mol) of polyether macromonomer B4 and 0.48g (0.002mol) of hydrophobic monomer C13 were charged into a reaction vessel, 173.4g of water was added thereto, and the reaction solution was stirred to be purged with nitrogen.
(2) 0.26g of potassium persulfate was dissolved in 2.88g (0.04mol) of the unsaturated carboxylic acid monomer A1, and the solution was added dropwise to the reaction solution obtained in step (1) under nitrogen atmosphere at 80 ℃ under stirring over 3 hours, and the reaction was continued for 3 hours after the completion of the addition.
The weight average molecular weight of the prepared polycarboxylate superplasticizer is 54200 g/mol.
Example 5
(1) 10g (0.01mol) of polyether macromonomer B1 and 0.60g (0.003mol) of hydrophobic monomer C11 were charged into a reaction vessel, 89.5g of water was added thereto, and stirred to form a reaction solution, and nitrogen gas was introduced to expel air.
(2) 0.09g of potassium persulfate was dissolved in 4.32g (0.06mol) of the unsaturated carboxylic acid monomer A1, and the solution was added dropwise to the reaction solution obtained in step (1) under nitrogen atmosphere at 60 ℃ under stirring over 1 hour, and the reaction was continued for 5 hours after completion of the addition.
The weight average molecular weight of the prepared polycarboxylate superplasticizer is 58700 g/mol.
Example 6
(1) 20g (0.01mol) of polyether macromonomer B2 and 0.60g (0.003mol) of hydrophobic monomer C11 were charged into a reaction vessel, 103g of water was added thereto, and the reaction solution was stirred to expel the air by introducing nitrogen.
(2) 0.15g of potassium persulfate was dissolved in 5.17g (0.06mol) of the unsaturated carboxylic acid monomer A2, and the solution was added dropwise to the reaction solution obtained in step (1) under nitrogen atmosphere at 80 ℃ under stirring over 3 hours, and the reaction was continued for 3 hours after the completion of the addition.
The weight average molecular weight of the prepared polycarboxylate superplasticizer is 46500 g/mol.
Example 7
(1) 24g (0.01mol) of polyether macromonomer B5 and 0.4g (0.002mol) of hydrophobic monomer C11 were charged into a reaction vessel, 109g of water was added thereto, and the reaction solution was stirred to expel air by introducing nitrogen.
(2) 0.16g of potassium persulfate was dissolved in 2.88g (0.04mol) of the unsaturated carboxylic acid monomer A1, and the solution was added dropwise to the reaction solution obtained in step (1) under nitrogen atmosphere at 80 ℃ under stirring over 3 hours, and the reaction was continued for 3 hours after the completion of the addition.
The weight average molecular weight of the prepared polycarboxylate superplasticizer is 51300 g/mol.
Example 8
The operation and other conditions were the same as in example 1 except that: the hydrophobic monomer in the step (1) is C21.
The weight average molecular weight of the prepared polycarboxylate superplasticizer is 43400 g/mol.
Example 9
The operation and other conditions were the same as in example 1 except that: the hydrophobic monomers in the step (1) are C11 and C21 in a molar ratio of 1: 0.5.
The weight average molecular weight of the prepared polycarboxylate superplasticizer is 43100 g/mol.
Example 10
The operation and other conditions were the same as in example 2 except that: the hydrophobic monomer in the step (1) is C22.
The weight average molecular weight of the prepared polycarboxylate superplasticizer is 48900 g/mol.
Example 11
The operation and other conditions were the same as in example 2 except that: the hydrophobic monomer in the step (1) is C23.
The weight average molecular weight of the prepared polycarboxylate superplasticizer is 50200 g/mol.
Example 12
The operation and other conditions were the same as in example 2 except that: the hydrophobic monomers in the step (1) are C12 and C22 in a molar ratio of 1: 0.2.
The weight average molecular weight of the prepared polycarboxylate superplasticizer is 49200 g/mol.
Example 13
The operation and other conditions were the same as in example 2 except that: the hydrophobic monomers in the step (1) are C12 and C23 in a molar ratio of 1: 0.2.
The weight average molecular weight of the prepared polycarboxylate superplasticizer is 49800 g/mol.
Example 14
The operation and other conditions were the same as in example 6 except that: the hydrophobic monomers in the step (1) are C11 and C22 in a molar ratio of 1: 0.2.
The weight average molecular weight of the prepared polycarboxylic acid water reducing agent is 47700 g/mol.
Comparative example 1
(1) 10g (0.01mol) of polyether macromonomer B1 and 0.28g (0.002mol) of hydrophobic monomer C4 were charged into a reaction vessel, 52.6g of water was added thereto, and stirred to form a reaction solution, and nitrogen gas was introduced to discharge air.
(2) 0.08g of potassium persulfate was dissolved in 2.88g (0.04mol) of the unsaturated carboxylic acid monomer A1, and the solution was added dropwise to the reaction solution obtained in step (1) under nitrogen atmosphere at 80 ℃ under stirring over 3 hours, and the reaction was continued for 3 hours after completion of the addition.
The weight average molecular weight of the prepared polycarboxylate superplasticizer is 39800 g/mol.
Comparative example 2
(1) 10g (0.01mol) of polyether macromonomer B1 and 0.65g (0.002mol) of hydrophobic monomer C5 were charged into a reaction vessel, 81g of water was added thereto, and the reaction solution was stirred to be purged with nitrogen.
(2) 0.08g of potassium persulfate was dissolved in 2.88g (0.04mol) of the unsaturated carboxylic acid monomer A1, and the solution was added dropwise to the reaction solution obtained in step (1) under nitrogen atmosphere at 80 ℃ under stirring over 3 hours, and the reaction was continued for 3 hours after completion of the addition.
The weight average molecular weight of the prepared polycarboxylate superplasticizer is 38500 g/mol.
Comparative example 3
(1) 20g (0.01mol) of polyether macromonomer B2 and 1.06g (0.005mol) of hydrophobic monomer C12 were charged into a reaction vessel, 143.6g of water was added thereto, and the reaction solution was stirred to remove air by introducing nitrogen.
(2) 0.14g of potassium persulfate was dissolved in 2.88g (0.04mol) of the unsaturated carboxylic acid monomer A1, and the solution was added dropwise to the reaction solution obtained in step (1) under nitrogen atmosphere at 80 ℃ under stirring over 3 hours, and the reaction was continued for 3 hours after the completion of the addition.
The weight average molecular weight of the prepared polycarboxylate superplasticizer is 51400 g/mol.
Comparative example 4
(1) 20g (0.01mol) of polyether macromonomer B2 was charged into a reaction vessel, 91.5g of water was added, and the reaction solution was stirred to expel air by introducing nitrogen.
(2) 0.14g of potassium persulfate was dissolved in 2.88g (0.04mol) of the unsaturated carboxylic acid monomer A1, and the solution was added dropwise to the reaction solution obtained in step (1) under nitrogen atmosphere at 80 ℃ under stirring over 3 hours, and the reaction was continued for 3 hours after the completion of the addition.
The weight average molecular weight of the prepared polycarboxylate superplasticizer is 31400 g/mol.
Fluidity of cement paste
The fluidity of the cement paste was measured by using the GB8077-2016 standard, wherein 300g of 52.5R.P.II cement was used in a small field, and the amount of water added was 87g, and the fluidity of the cement paste was measured on a plate glass after completion of the stirring, and the results are shown in Table 2.
TABLE 2 Cement paste fluidity
As can be seen from Table 2, the polycarboxylic acid water reducing agent prepared by the present invention has good dispersing ability for cement at low blending amount and shows good dispersion retaining ability.
Concrete Properties
Carrying out gas content and water reducing rate tests with reference to GB8076-2016 concrete admixture; a slump test and a slump loss test with time are carried out according to GB50080-2016 standard on performance test methods of common concrete mixtures, wherein the mixing amount of the polycarboxylic acid water reducing agent is 0.15 wt%, and test results are shown in Table 3.
TABLE 3 concrete Properties
As can be seen from Table 3, the addition of the modified concrete admixture of the present invention, specifically the polycarboxylic acid water reducing agent of the present invention, can provide a strong water reducing ability at a low blending amount and shows a significant advantage in slump-retaining ability.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The modified concrete admixture comprises a modified polycarboxylic acid water reducing agent, wherein the polycarboxylic acid water reducing agent is formed by polymerizing an unsaturated carboxylic acid monomer, a polyether macromonomer and a hydrophobic monomer in a molar ratio of 4-6: 1: 0.2-0.3;
wherein the unsaturated carboxylic acid monomer is acrylic acid and/or methacrylic acid;
the structural formula of the polyether macromonomer is shown as formula I:
in the formula I, R1、R2、R3And R4Each independently is H or CH3B is an integer of 20 to 120;
the structural formula of the hydrophobic monomer is shown as formula II:
in the formula II, R5Is H or CH3，R6Is C8-C12 alkyl.
2. The modified concrete admixture according to claim 1, wherein the weight average molecular weight of the polycarboxylic acid water reducing agent is 20000 to 100000g/mol, preferably 40000 to 60000 g/mol.
3. The modified concrete admixture according to claim 1 or 2, wherein the polyether macromonomer is allyl polyoxyethylene ether, methallyl polyoxyethylene ether or prenyl polyoxyethylene ether;
preferably, in the polyether macromonomer shown in the formula I, b is an integer of 40-100, preferably an integer of 40-70.
4. The modified concrete admixture according to any one of claims 1 to 3, wherein the hydrophobic monomer is one or more selected from the group consisting of n-octyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, 4-t-butylcyclohexyl (meth) acrylate, 1-ethylcyclohexyl (meth) acrylate and isobornyl (meth) acrylate;
preferably, the hydrophobic monomers include a first hydrophobic monomer and a second hydrophobic monomer, the first hydrophobic monomer is one or more selected from the group consisting of n-octyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate and lauryl (meth) acrylate, the second hydrophobic monomer is one or more selected from the group consisting of 4-tert-butylcyclohexyl (meth) acrylate, 1-ethylcyclohexyl (meth) acrylate and isobornyl (meth) acrylate, and the molar ratio of the first hydrophobic monomer to the second hydrophobic monomer is 1: 0.2-0.5.
5. The method for producing a modified concrete admixture according to any one of claims 1 to 4, wherein the method for producing a polycarboxylic acid water-reducing agent comprises the steps of:
(1) adding a polyether macromonomer, a hydrophobic monomer and water into a reaction container, and stirring and mixing to obtain a reaction solution;
(2) and (2) dropwise adding an unsaturated carboxylic acid monomer into the reaction liquid obtained in the step (1) at the temperature of 60-90 ℃ in the presence of an initiator, and continuing to react after dropwise adding is finished to obtain the polycarboxylic acid water reducing agent.
6. The preparation method according to claim 5, wherein the amount of water used in the step (1) is 3 to 9 times, preferably 4 to 6 times, the total mass of the unsaturated carboxylic acid monomer, the polyether macromonomer and the hydrophobic monomer.
7. The production method according to claim 5 or 6, wherein the initiator is ammonium persulfate, sodium persulfate, or potassium persulfate;
preferably, the amount of the initiator used in the step (2) is 0.1-1% by mass based on the total mass of the unsaturated carboxylic acid monomer, the polyether macromonomer and the hydrophobic monomer.
8. The production method according to any one of claims 5 to 7, wherein the step (2) is performed under an inert atmosphere, preferably a nitrogen atmosphere, a helium atmosphere, or an argon atmosphere.
9. Use of the modified concrete admixture of any one of claims 1 to 4 in concrete.
10. The use of claim 9, wherein the amount of the polycarboxylic acid water reducer added in the modified concrete admixture is 0.1-0.5% of the total gelled material in the concrete.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2018154711A (en) * | 2017-03-16 | 2018-10-04 | 株式会社日本触媒 | Polycarboxylic acid-based copolymer, cement dispersion agent, concrete admixture, and concrete composition |
| CN111777724A (en) * | 2020-08-03 | 2020-10-16 | 辛集市旭远新材料科技有限公司 | Polycarboxylate superplasticizer and preparation method and application thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2018154711A (en) * | 2017-03-16 | 2018-10-04 | 株式会社日本触媒 | Polycarboxylic acid-based copolymer, cement dispersion agent, concrete admixture, and concrete composition |
| CN111777724A (en) * | 2020-08-03 | 2020-10-16 | 辛集市旭远新材料科技有限公司 | Polycarboxylate superplasticizer and preparation method and application thereof |
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Application publication date: 20201120 |