CN112194762B - Preparation method of non-crosslinked reticular polycarboxylic acid water reducing agent - Google Patents
Preparation method of non-crosslinked reticular polycarboxylic acid water reducing agent Download PDFInfo
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- CN112194762B CN112194762B CN202011069960.5A CN202011069960A CN112194762B CN 112194762 B CN112194762 B CN 112194762B CN 202011069960 A CN202011069960 A CN 202011069960A CN 112194762 B CN112194762 B CN 112194762B
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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
- 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
- C08F2/00—Processes of polymerisation
- C08F2/38—Polymerisation using regulators, e.g. chain terminating agents, e.g. telomerisation
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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
- C08F4/00—Polymerisation catalysts
- C08F4/40—Redox systems
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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
Abstract
The invention discloses a preparation method of a non-crosslinked reticular polycarboxylic acid water reducing agent, which comprises the following steps: and (3) adopting peroxide-polymerizable tertiary amine to construct an oxidation-reduction initiation system to initiate an unsaturated polyether macromonomer and an unsaturated acid small monomer to carry out free radical polymerization reaction to obtain the non-crosslinked net-shaped polycarboxylic acid water reducer. The raw materials used in the reaction production are few in variety and simple in process, and the reticular polycarboxylic acid structure greatly reduces the adsorption condition of the polyether side chain in the intercalation of soil, so that the polyether side chain has excellent mud resistance and powder resistance; in addition, the product improves the adaptability of the polycarboxylic acid water reducing agent and a concrete material, improves the dispersibility of cement, and enhances the plasticity retention capacity and the bleeding inhibition capacity of the concrete on the premise of high water reduction.
Description
Technical Field
The invention belongs to the technical field of polycarboxylic acid water reducing agents for building materials, namely cement concrete, and particularly relates to a non-crosslinked net-shaped polycarboxylic acid water reducing agent prepared by carrying out free radical polymerization on a double-active center formed by a redox initiation system constructed by peroxide-polymerizable tertiary amine.
Background
The polycarboxylate superplasticizer has the advantages of low mixing amount, high water reducing rate, adjustable function, strong molecular designability, environmental protection and the like, and is widely applied to the concrete construction engineering industry. However, a large number of engineering examples and researches show that compared with the traditional second-generation water reducing agents such as naphthalene-based, sulfamate-based and melamine-based water reducing agents, the polycarboxylic acid water reducing agent is more sensitive to the mud content of the aggregate, the mud in the aggregate can adsorb the polycarboxylic acid water reducing agent, the mixing amount of the polycarboxylic acid water reducing agent is increased along with the increase of the mud content, the water reducing and dispersing capacity is reduced, the slump retaining effect is reduced, and the workability of fresh concrete is greatly reduced. However, when the mud content in the aggregate is low, the polycarboxylic acid water reducing agent shows a large water reducing rate in concrete, and the phenomena of large mixing amount fluctuation, insufficient water retention, bottom scraping, bleeding, overlong condensation time, large strength deviation and the like can occur in the actual mixing process. With the continuous development of the concrete industry and the gradual depletion of raw material resources, more and more concrete mixing plants are forced to bear the pressure of raw materials, deteriorated sandstone resources have to be used, and particularly in large and medium-sized cities, a plurality of mixing plants use high-content silt sand, tailing sand and mixed sand of the silt sand and the tailing sand. The aggregates with high mud content have super-strong adsorption capacity on the polycarboxylic acid water reducing agent, and can generate very adverse effects on the dosage of the polycarboxylic acid water reducing agent, the working performance, the mechanical strength, the durability and the like of concrete.
Generally speaking, the adaptability of the existing common polycarboxylic acid water reducing agent with a comb-type structure to soil is poor, and a polycarboxylic acid water reducing agent with strong adaptability to soil needs to be developed by changing the comb-type structure of the traditional polycarboxylic acid water reducing agent from the molecular structure of the polycarboxylic acid water reducing agent, so that the national applicability of the polycarboxylic acid water reducing agent can be greatly improved, and the polycarboxylic acid water reducing agent has important significance for the development of the building industry.
The development of a non-crosslinked net-shaped polycarboxylic acid water reducing agent is a breakthrough of the traditional water reducing agent technology, and the net-shaped polycarboxylic acid water reducing agents described in most patents realize excellent performance mainly by adopting the crosslinking condition between polycarboxylic acid molecules, for example, patent CN106046274A discloses a net-shaped polycarboxylic acid water reducing agent which is formed by connecting two isolated polycarboxylic acid molecules through diene amines, so that the steric hindrance of the polycarboxylic acid molecules is increased, and the change of a polycarboxylic acid structure from a comb type to a net-shaped structure is realized. The production process is relatively complex, and the molded polycarboxylic acid molecules are crosslinked into a net structure through diene amines, so that the polycarboxylic acid molecules with the net structure have the phenomena of large molecular weight, reduced mother liquor thickening and water reducing rate and the like; in patent CN106519143A, a star polycarboxylic acid water reducing agent is disclosed, which is prepared by polymerization reaction of monomers with double bonds, pentaerythritol tris (3-mercaptopropionate), triethanolamine tris (3-mercaptopropionate), glucose tetrakis (3-mercaptopropionate), ethylene diamine tetra (acetic acid-2-mercaptoethyl ester) nucleating agent, initiator, and terminal double bond polyoxyethylene ether as raw materials. The nucleating agent used in the invention has poor compatibility with water, and unreacted nucleating agent can float in the water reducing agent in the finished product. In addition, the temperature required by the reaction is high, the industrial conditions are harsh, and the chain transfer efficiency by the nucleating agent is not high.
Disclosure of Invention
The invention aims to provide a preparation method of a non-crosslinked net-shaped polycarboxylic acid water reducing agent with simple production process in order to enrich and improve the defects of the prior art. Unsaturated polyether macromonomer and unsaturated acid small monomer are subjected to free radical polymerization reaction under the combined action of an initiator and a reducing agent with chain transfer effect to obtain the non-crosslinked net-shaped polycarboxylic acid water reducing agent. The reaction production raw materials and the process are simple, the condition that polyether side chains in the polycarboxylic acid water reducing agent are adsorbed in the interlayer of the soil is greatly reduced due to the net structure, the adaptability of the polycarboxylic acid water reducing agent and a concrete material is improved, the dispersibility of cement is improved, and the plasticity retention capacity and the bleeding inhibition capacity of the concrete are enhanced on the premise of high water reduction.
The technical scheme of the invention is as follows: a preparation method of a non-crosslinked reticular polycarboxylic acid water reducing agent comprises the following specific steps:
under the combined action of a peroxide initiator and a reducing agent with a chain transfer effect, maintaining an unsaturated polyether macromonomer and an unsaturated acid small monomer at 5-35 ℃ to perform free radical polymerization for 1.0-3.0 h to obtain a copolymerization product, adding alkali to adjust the pH value to 5-7, and adding deionized water to obtain a non-crosslinked reticular polycarboxylic acid water reducer with the mass concentration of 20-50%; wherein the molar ratio of the unsaturated polyether macromonomer to the unsaturated acid small monomer to the initiator to the reducing agent is 1: (3.0-7.0): (0.005-0.01): (0.1-0.25);
preferably, the unsaturated polyether macromonomer is one or a combination of more than two of allyl vinyl ether, methyl allyl vinyl ether, isopentenyl vinyl ether or 4-hydroxybutyl vinyl ether, and the molecular weight of the unsaturated polyether macromonomer is Mw:1100g/mol to 6000g/mol.
Preferably, the unsaturated acid small monomer is one or a combination of more than two of acrylic acid, methacrylic acid, sodium methallylsulfonate, glutaconic acid, maleic acid or fumaric acid and 3-methylpentenedioic acid.
Preferably, the initiator is one or a combination of more than two of dibenzoyl peroxide, ammonium persulfate, sodium persulfate and potassium persulfate.
Preferably, the reducing agent having a chain transfer effect is one of N- (N, N-dimethylaminomethyl) acrylamide, N- (N, N-dimethylaminomethyl) methacrylamide, N- (3-dimethylaminopropyl) acrylamide or N- (3-dimethylaminopropyl) methacrylamide.
The reducing agent can participate in both chain initiation and chain propagation, such as the process of chain initiation to form branched polymer under the action of an initiator according to the following schematic formula:
wherein R is 1 Is independently a H atom or a methyl group; r 2 Is alkyl of 1 to 3 carbon atoms; m represents a monomer.
Preferably, the alkali is one or the combination of more than two of potassium hydroxide, sodium gluconate or sodium thiosulfate.
The molecular weight of the non-crosslinked net-shaped polycarboxylic acid water reducing agent prepared by the method is preferably 30000g/mol to 50000gmol.
The molecular structural formula of the prepared non-crosslinked reticular polycarboxylic acid water reducing agent is as follows:
wherein R is 1 Is independently a H atom or a methyl group; r 2 Is alkyl of 1 to 3 carbon atoms; r 3 Is unsaturated polyether macromonomer; r 4 Is unsaturated acid small monomer; a is (x＝1,2,3,4,5……≤10) The polymerization degree of the unsaturated macromonomer is between 1 and 5; b is a mixture of (y＝1,2,3,4,5……≤10) The polymerization degree of the unsaturated acid small monomer is between 1 and 10.
The invention adopts peroxide-polymerizable tertiary amine to construct an oxidation-reduction initiation system, initiates the free radical copolymerization reaction of an unsaturated polyether macromonomer and an unsaturated acid small monomer, and generates the polycarboxylic acid water reducer with a net structure.
Has the advantages that:
1. the invention relates to a non-crosslinked net-shaped polycarboxylic acid water reducing agent synthesized by constructing an oxidation-reduction initiation system by peroxide-polymerizable tertiary amine, and the reducing agent adopted is polymerizable tertiary amine, so that the reducing agent not only can participate in chain initiation, but also can participate in chain growth as a polymerization monomer, and therefore, a highly branched polymer can be simply and efficiently prepared. The tertiary amine also has a chain transfer effect, and more amine free radicals with initiating activity can be generated due to the fact that the chain transfer rate of the peroxide to the tertiary amine is high, and the more free radicals, the more chains are generated, so that the molecular weight is reduced, and the occurrence of a cross-linking phenomenon is effectively avoided.
2. The non-crosslinked reticular polycarboxylic acid water reducing agent synthesized by the invention is prepared by one step of free radical polymerization reaction, and has the characteristics of simple process flow, mild reaction conditions, controllable molecular weight, good product solubility, stable generated product, high finished product yield and the like.
3. Compared with the common comb-type polycarboxylate superplasticizer, the non-crosslinked net-type polycarboxylate superplasticizer prepared by the invention can weaken the intercalation adsorption phenomenon of long side chains of the polycarboxylate superplasticizer on soil to the greatest extent due to the unique structural advantages, has very small influence degree on the water reducing rate in the concrete with poor materials, and shows extremely high water reducing capacity and strong material adaptability.
4. On the premise of reducing water and retaining slump, the non-crosslinked reticular polycarboxylic acid water reducing agent product prepared by the invention has a hydrophilic reticular structure, so that the non-crosslinked reticular polycarboxylic acid water reducing agent product has a certain water retaining effect, and can inhibit the phenomena of bleeding and bottom scraping of concrete.
5. The non-crosslinked reticular polycarboxylate superplasticizer product prepared by the method can be prepared into an aqueous solution with other carboxylate superplasticizers, has stable performance, does not delaminate or precipitate during storage, and is convenient to transport.
Detailed Description
The present invention will be described in detail with reference to the following examples, which are only a part of the examples of the present invention and are only for illustrating the present invention and not for limiting the present invention.
Example 1
1.0mol of molecular weight Mw:2400g/mol of allyl vinyl ether, 3.0mol of methacrylic acid, 0.005mol of dibenzoyl peroxide and 0.1mol of N- (N, N-dimethylaminomethyl) acrylamide are kept at 30 ℃ for free radical polymerization for 3.0h, potassium hydroxide is added to adjust the pH value to 5, and deionized water is added to obtain the non-crosslinked reticular polycarboxylic acid water reducer with the molecular weight Mw of 50000g/mol and the mass concentration of 20%.
Wherein R is 1 Is a hydrogen atom; r 2 Is alkyl of 1 carbon atom; r is 3 Is allyl vinyl ether; r 4 Is methacrylic acid; a is (x＝1,2,3……≤6) The polymerization degree of the unsaturated macromonomer is between 1 and 5; b (y＝1,2,3……≤6) The polymerization degree of the unsaturated acid small monomer is between 1 and 10.
Example 2
1.0mol of molecular weight Mw:1100g/mol of 4-hydroxybutyl vinyl ether, 4.0mol of acrylic acid, 0.01mol of potassium persulfate and 0.25mol of N- (3-dimethylaminopropyl) methacrylamide are kept at 5 ℃ for free radical polymerization reaction for 1.5h, sodium gluconate and sodium hydroxide are added to adjust the pH value to 7, and deionized water is added to obtain the non-crosslinked reticular polycarboxylic acid water reducer with the molecular weight Mw of 32300g/mol and the mass concentration of 50%.
Wherein R is 1 Is methyl; r 2 Is alkyl of 3 carbon atoms; r 3 Is 4-hydroxybutyl vinyl ether; r 4 Is acrylic acid; a is (x＝1,2,3,4,5……≤10) The polymerization degree of the unsaturated macromonomer is between 1 and 5; b is a mixture of (y＝1,2,3,4,5……≤10) The polymerization degree of the unsaturated acid small monomer is between 1 and 10.
Example 3
1.0mol of molecular weight Mw:6000g/mol of 4-hydroxybutyl vinyl ether, 3.0mol of acrylic acid, 4mol of sodium methallyl sulfonate, 0.008mol of ammonium persulfate and 0.20mol of N- (3-dimethylaminopropyl) acrylamide are kept at 10 ℃ for free radical polymerization reaction for 1.0h, sodium gluconate and potassium hydroxide are added to adjust the pH value to 7, and deionized water is added to obtain the non-crosslinked reticular polycarboxylic acid water reducer with the molecular weight Mw of 40100g/mol and the mass concentration of 40%.
Wherein R is 1 Is a hydrogen atom; r is 2 Is alkyl of 3 carbon atoms; r 3 Is 4-hydroxybutyl vinyl ether; r 4 Is one or two of acrylic acid or methallyl sulfonic acid; a is a (x＝1,2,3,4……≤8) The polymerization degree of the unsaturated macromonomer is between 1 and 5; b is a mixture of (y＝1,2,3,4……≤8) The polymerization degree of the unsaturated acid small monomer is between 1 and 10.
Example 4
1.0mol of molecular weight Mw:4000g/mol of methyl allyl vinyl ether, 4.0mol of acrylic acid, 1mol of sodium methallyl sulfonate, 0.005mol of sodium persulfate, 0.005mol of potassium persulfate and 0.25mol of N- (N, N-dimethyl aminomethyl) methacrylamide, the mixture is kept at 20 ℃ for free radical polymerization reaction for 2.0h, sodium thiosulfate is added to adjust the pH value to 6, deionized water is added to obtain the non-crosslinked reticular polycarboxylic acid water reducer with the molecular weight Mw of 38200g/mol and the mass concentration of 35%.
Wherein R is 1 Is methyl; r is 2 Is alkyl of 1 carbon atom; r 3 Is methyl allyl vinyl ether; r 4 Is one or two of acrylic acid or methallyl sulfonic acid; a is a (x＝1,2,3,4,5……≤10) Is unsaturated macromonomer with polymerization degree of 1 to5 or more; b (y＝1,2,3,4,5……≤10) The polymerization degree of the unsaturated acid small monomer is between 1 and 10.
Example 5
1.0mol of molecular weight Mw:2900g/mol of isopentenyl vinyl ether, 2.0mol of acrylic acid, 2mol of maleic acid, 3mol of fumaric acid, 0.005mol of sodium persulfate, 0.005mol of ammonium persulfate and 0.25mol of N- (N, N-dimethylaminomethyl) methacrylamide are kept at 35 ℃ for free radical polymerization reaction for 3.0h, sodium thiosulfate and sodium hydroxide are added to adjust the pH value to 6, and deionized water is added to obtain the non-crosslinked reticular polycarboxylic acid water reducer with the molecular weight Mw of 30000g/mol and the mass concentration of 40%.
Wherein R is 1 Is methyl; r 2 Is alkyl of 1 carbon atom; r 3 Is isopentenyl vinyl ether; r 4 Is one or more of acrylic acid, maleic acid or fumaric acid; a is (x＝1,2,3,4,5……≤10) The polymerization degree of the unsaturated macromonomer is between 1 and 5; b (y＝1,2,3,4,5……≤10) The polymerization degree of the unsaturated acid small monomer is between 1 and 10.
Example 6
0.6mol of molecular weight Mw:2900g/mol of isopentenyl vinyl ether, 0.4mol of molecular weight Mw:2400g/mol of methyl allyl vinyl ether, 2.0mol of acrylic acid, 3mol of 3-methylpentenedioic acid, 0.005mol of sodium persulfate, 0.005mol of ammonium persulfate and 0.18mol of N- (N, N-dimethylaminomethyl) acrylamide are kept at 10 ℃ for free radical polymerization reaction for 3.0h, sodium thiosulfate and sodium gluconate are added to adjust the pH value to 6, and deionized water is added to obtain the non-crosslinked reticular polycarboxylic acid water reducer with the molecular weight Mw of 40400g/mol and the mass concentration of 20%.
Wherein R is 1 Is a hydrogen atom; r 2 Is alkyl of 1 carbon atom; r is 3 Is one or two of isopentenyl vinyl ether or methyl allyl vinyl ether; r 4 Is one or two of acrylic acid or 3-methylpentenedioic acid; a a (x＝1,2,3,4……≤7) The polymerization degree of the unsaturated macromonomer is between 1 and 5; b is a mixture of (y＝1,2,3,4……≤7) The polymerization degree of the unsaturated acid small monomer is between 1 and 10.
Example 7
0.7mol of molecular weight Mw:2400g/mol of isopentenyl vinyl ether, 0.3mol of molecular weight Mw:2900g/mol of allyl vinyl ether, 2.0mol of methacrylic acid, 2mol of maleic acid, 2mol of glutaconic acid, 0.005mol of sodium persulfate, 0.005mol of ammonium persulfate and 0.18mol of N- (N, N-dimethylaminomethyl) acrylamide are kept at 25 ℃ for free radical polymerization reaction for 3.0h, sodium hydroxide and sodium gluconate are added to adjust the pH value to 6, and deionized water is added to obtain the non-crosslinked reticular polycarboxylic acid water reducer with the molecular weight Mw of 43100g/mol and the mass concentration of 25%.
Wherein R is 1 Is a hydrogen atom; r 2 Is alkyl of 1 carbon atom; r 3 Is one or two of isopentenyl vinyl ether or allyl vinyl ether; r 4 Is one or two of methacrylic acid, maleic acid or glutaconic acid; a is (x＝1,2,3,4……≤7) The polymerization degree of the unsaturated macromonomer is between 1 and 5; b (y＝1,2,3,4……≤7) The polymerization degree of the unsaturated acid small monomer is between 1 and 10.
Example 8
0.3mol of molecular weight Mw:2400g/mol of isopentenyl vinyl ether, 0.3mol of molecular weight Mw:2900g/mol of allyl vinyl ether, 0.4mol of molecular weight Mw:6000g/mol of 4-hydroxybutyl vinyl ether, 2.0mol of methacrylic acid, 3mol of sodium methallylsulfonate, 2mol of fumaric acid, 0.005mol of sodium persulfate, 0.005mol of ammonium persulfate and 0.25mol of N- (N, N-dimethyl aminomethyl) acrylamide are kept at 15 ℃ for free radical polymerization reaction for 3.0h, sodium hydroxide is added to adjust the pH value to 7, and deionized water is added to obtain the non-crosslinked reticular polycarboxylic acid water reducer with the molecular weight Mw of 47300g/mol and the mass concentration of 45%.
Wherein R is 1 Is a hydrogen atom; r is 2 Is alkyl of 1 carbon atom; r is 3 Is one or more of isopentenyl vinyl ether, allyl vinyl ether or 4-hydroxybutyl vinyl ether; r is 4 Is one or more of methacrylic acid, sodium methallyl sulfonate or fumaric acid; a is a (x＝1,2,3,4,5……≤10) The polymerization degree of the unsaturated macromonomer is between 1 and 5; b (y＝1,2,3,4,5……≤10) The polymerization degree of the unsaturated acid small monomer is between 1 and 10.
Comparative example 1
0.3mol of molecular weight Mw:2400g/mol of isopentenyl vinyl ether, 0.3mol of molecular weight Mw:2900g/mol of allyl vinyl ether, 0.4mol of molecular weight Mw:6000g/mol of 4-hydroxybutyl vinyl ether, 2.0mol of methacrylic acid, 3mol of sodium methallylsulfonate, 2mol of fumaric acid, 0.005mol of sodium persulfate, 0.005mol of ammonium persulfate, 0.2mol of 2-mercaptopropionic acid and 0.0025mol of L-ascorbic acid are subjected to free radical polymerization reaction for 3.0h at 15 ℃, sodium hydroxide is added to adjust the pH value to 7, and deionized water is added to obtain the common polycarboxylic acid water reducer with the comb-type structure, wherein the molecular weight Mw of the common polycarboxylic acid water reducer is 29300g/mol, and the mass concentration of the common polycarboxylic acid water reducer is 45%.
Testing the fluidity of the cement paste: the samples obtained in examples 1 to 8 and comparative example 1 and a commercial high-quality carboxylic acid water reducing agent were subjected to a net slurry fluidity test with reference to GB8077-2012, test method for homogeneity of concrete admixtures. The W/C is 0.29, and the flexural strength of the water reducing agent is 0.06 percent of the dosage of the reference cement;
TABLE 1 Net slurry fluidity and loss data for different samples
Testing the fluidity of the bentonite-containing cement paste: the samples obtained in examples 1 to 8 and comparative example 1 were subjected to a comparison test of net slurry fluidity with a commercially available high-quality carboxylic acid water reducing agent by referring to GB8077-2012, test method for homogeneity of concrete admixture. The W/C is 0.29, the bending solid of the water reducing agent is 0.09 percent of the dosage of the standard cement, and the bentonite is 3.0 percent of the dosage of the standard cement. As can be seen from the following table, the net slurry fluidity and the 60min holding capacity of the samples obtained in examples 1 to 8 are both significantly better than those of the comparative example 1 and the commercial high-quality carboxylic water reducing agent, which indicates that the mud resistance and the holding capacity of the synthesized non-crosslinked reticular polycarboxylic water reducing agent are both significantly better than those of the carboxylic water reducing agent with a comb-shaped structure.
TABLE 2 Net slurry fluidity and loss data for different samples
Testing the performance of the concrete: the slump loss and concrete strength contrast tests of the machine-made sand concrete and the comparative examples 1 and the commercial high-quality carboxylic acid water reducing agent are carried out according to GB8076-2008 concrete admixture and GB8077-2012 concrete admixture homogeneity test method. The specific machine-made sand data, concrete mix ratios and test results are shown in tables 3, 4 and 5. From the test results, the synthesized non-crosslinked reticular polycarboxylic acid water reducing agent has outstanding mud resistance, water retention and retention capability in poor materials.
TABLE 3 Nanjing-oriented machine sand making data parameters
Table 4 machine-made sand concrete mix proportion unit: kg/m 3
Remarking: the folding and fixing dosage of the additive is 0.16 percent of that of the rubber material
TABLE 5 concrete slump retaining and mechanical Properties of different samples
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, so that any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention will still fall within the scope of the technical solution of the present invention without departing from the content of the technical solution of the present invention.
Claims (5)
1. A preparation method of a non-crosslinked reticular polycarboxylic acid water reducing agent comprises the following specific steps:
under the combined action of a peroxide initiator and a reducing agent with a chain transfer effect, maintaining an unsaturated polyether macromonomer and an unsaturated acid small monomer at 5-25 ℃ to perform free radical polymerization for 1.0-3.0 h to obtain a copolymerization product, adding alkali to adjust the pH value to 5-7, and adding deionized water to obtain a non-crosslinked reticular polycarboxylic acid water reducer with the mass concentration of 20-50%; wherein the molar ratio of the unsaturated polyether macromonomer to the unsaturated acid small monomer to the initiator to the reducing agent is 1: (3.0-7.0): (0.005-0.01): (0.1 to 0.25); the unsaturated polyether macromonomer is one or the combination of more than two of allyl vinyl ether, methyl allyl vinyl ether, isopentenyl vinyl ether or 4-hydroxybutyl vinyl ether, and the molecular weight of the unsaturated polyether macromonomer is Mw:1100 g/mol-6000 g/mol; the reducing agent is one of N- (N, N-dimethylaminomethyl) acrylamide, N- (N, N-dimethylaminomethyl) methacrylamide, N- (3-dimethylaminopropyl) acrylamide or N- (3-dimethylaminopropyl) methacrylamide.
2. The method according to claim 1, wherein the unsaturated acid small monomer is one or a combination of two or more of acrylic acid, methacrylic acid, sodium methallylsulfonate, glutaconic acid, maleic acid, or fumaric acid, and 3-methylpentenedioic acid.
3. The method according to claim 1, wherein the initiator is one or more of dibenzoyl peroxide, ammonium persulfate, sodium persulfate and potassium persulfate.
4. The method according to claim 1, wherein the base is one or a combination of two or more of potassium hydroxide, sodium gluconate, and sodium thiosulfate.
5. The preparation method according to claim 1, wherein the molecular weight Mw of the prepared non-crosslinked reticular polycarboxylic acid water reducer is 30000g/mol to 50000g/mol.
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| CN110396159B (en) * | 2019-09-11 | 2022-04-19 | 江苏博思通新材料有限公司 | Preparation method of polycarboxylic acid water reducer containing claw-type short side chains |
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