CN114478946B - Polycarboxylic acid concrete water reducer and preparation method thereof - Google Patents
Polycarboxylic acid concrete water reducer and preparation method thereof Download PDFInfo
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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
- C08F287/00—Macromolecular compounds obtained by polymerising monomers on to block polymers
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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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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Abstract
The invention discloses a polycarboxylic acid concrete water reducer and a preparation method thereof. The polycarboxylic acid concrete water reducer is prepared by taking EPEG, acrylic acid and itaconic acid modified inorganic materials as raw materials and carrying out free radical polymerization under the normal temperature condition. According to the invention, the itaconic acid modified inorganic material is introduced into the polycarboxylic acid type concrete water reducer, the nano titanium dioxide and the carbon nano tube have good nano size effect, play a role in connection and filling in concrete, refine the pore structure of concrete pairs, form an effective interface transition structure, and meanwhile, the nano titanium dioxide generates needle-shaped products in the concrete, so that the toughening effect of the concrete is improved, and the freezing resistance and chloride ion permeation resistance of the concrete are further improved.
Description
Technical Field
The invention relates to the technical field of additives for concrete, in particular to a polycarboxylic acid concrete water reducer and a preparation method thereof.
Background
Concrete is one of the most widely used building materials in the current building industry. The concrete is widely applied to various projects such as buildings, traffic, water conservancy, national defense and the like. A concrete admixture is a material added prior to or during the mixing of concrete to improve or harden the properties of the concrete. The concrete admixture is functionally divided into an admixture for improving fluidity of a concrete admixture, an admixture for adjusting setting and hardening properties of a concrete, an admixture for improving durability of a concrete, and an admixture for improving other properties of a concrete.
The water reducing agent is one of concrete additives, and can greatly reduce the water consumption of cement in the construction process, so that the prepared concrete still keeps good fluidity under the condition of reducing the water-cement ratio, the working performance of the concrete is improved, and the service life of the concrete is prolonged. The development of the concrete water reducer goes through three stages: firstly, the common water reducer represented by lignosulfonate has certain air entraining and retarding effects, but the cement has poor adaptability, abnormal coagulation is easy to occur in the stirring process, and the strength is low; second, contain naphthalene, melamine, anthracene, fatty acid, etc. second generation water reducing agent, but the mobility is bad, difficult to store, the shelf life is short, the application range is limited; and thirdly, the polycarboxylic acid water reducer has the characteristics of small mixing amount, high water reducing rate, good environmental protection performance, low manufacturing cost and the like, so that the polycarboxylic acid concrete water reducer is widely applied.
The polycarboxylic acid concrete water reducer is prepared by polymerizing unsaturated small monomers and a large monomer containing polyoxyethylene ether under the action of an initiator. The hydrophobic group of the polycarboxylic acid type concrete water reducer can be firmly bound on the surface of cement particles, and the side face of the hydrophilic group is deep into the aqueous solution, so that the cement particles can be dispersed due to large space volume.
However, although the traditional polycarboxylic acid concrete water reducer has excellent performance, certain reaction temperature is high and reaction time is long in polymerization reaction in the synthesis process, and grafting of functional monomers is low. When the temperature is low, the moisture in the concrete causes frost heaving when the temperature rises, and the concrete is broken, so that the structure of the concrete is seriously affected.
CN107902939a discloses an antifreeze polycarboxylate superplasticizer and a synthesis process thereof, wherein the antifreeze polycarboxylate superplasticizer comprises the following raw materials: antifreeze agent, acrylic acid, hydrogen peroxide, beta-carboxyethyl acrylate, maleic anhydride monomer, initiator, molecular weight regulator, fatty alcohol polyoxyethylene ether, monobasic unsaturated carboxylic acid and its derivative, vinyl ether polyoxyethylene, catalyst, gamma-polyglutamic acid, sand sagebrush gum, microcrystalline cellulose and feather protein; the antifreeze agent comprises the following raw materials: sodium 3-allyloxy-2-hydroxy propane sulfonate, allyl polyethylene glycol, calcium chloride, ammonium sulfate, silica fume and micro short fiber. The invention not only has the water-reducing property and slump retaining property, but also obviously improves the workability of the concrete, greatly reduces the sensitivity of the water reducer to water consumption, and the prepared water reducer has good compatibility to cement, small mixing amount, high water-reducing rate and good freezing-resisting effect, can obviously improve the freezing-thawing resistance durability of the concrete, is suitable for engineering use in cold areas, and has higher practical value. However, the invention adopts various raw materials and has harsh reaction conditions, the freezing resistance and the compression resistance are not obviously improved, and the chloride ion permeation resistance is not improved.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, the technical problem to be solved by the present invention is to provide a polycarboxylic acid type concrete water reducer which has the advantages of effectively improving the frost resistance and chloride ion permeation resistance of concrete and improving the compression resistance.
In order to achieve the aim, the invention provides a polycarboxylic acid concrete water reducer and a preparation method thereof.
The preparation method of the polycarboxylic acid concrete water reducer comprises the following steps:
(1) Adding 80-100 parts by weight of EPEG into 300-400 parts by weight of water, and uniformly mixing to prepare an EPEG aqueous solution; adding 0.05-0.2 weight part of sodium methacrylate sulfonate and 0.1-0.2 weight part of ascorbic acid into 20-30 weight parts of water, and uniformly mixing to obtain a mixed solution I; adding 1-3 parts by weight of acrylic acid, 0.5-1.6 parts by weight of hydrogen peroxide and 0.05-0.15 part by weight of hydrophobic acetic acid into 50-65 parts by weight of water, and uniformly mixing to obtain a mixed solution II;
(2) And (3) reacting the mixture in the EPEG water solution at 20-25 ℃ for 10-20min, then adding the mixed solution I and the mixed solution II, keeping the temperature of 20-25 ℃ for 3-5h, and then adding 25-30wt% of sodium hydroxide water solution to adjust the pH value to 6-8, thus obtaining the polycarboxylic acid concrete water reducer.
Although the traditional large monomer has excellent performance, certain high reaction temperature and long reaction time exist in the polymerization reaction in the synthesis process, and the grafting ratio of the functionalized monomer is lower. Therefore, the invention discloses a method for preparing a polycarboxylic acid concrete water reducer by adopting a redox system under normal temperature conditions. On the basis, itaconic acid modified 4-hydroxybutyl vinyl polyoxyethylene ether is further introduced, and is crosslinked with EPEG and acrylic acid at normal temperature to prepare a polycarboxylic acid concrete water reducing agent with a reticular structure, the existence of the reticular structure improves the adsorption force of the polycarboxylic acid concrete water reducing agent and concrete, the strength and compactness of the concrete are further improved, the penetration erosion of chloride ions is greatly reduced by the concrete with compact structure, the frost resistance, chloride ion penetration resistance and mechanical property of the concrete are further improved, meanwhile, the itaconic acid modified 4-hydroxybutyl vinyl polyoxyethylene ether provides larger steric hindrance, the dispersion property of cement slurry is improved, and the introduction of the itaconic acid modified 4-hydroxybutyl vinyl polyoxyethylene ether contains a large amount of ester groups, so that the polycarboxylic acid concrete water reducing agent can hydrolyze in the alkaline environment of cement and release a large amount of carboxyl groups, and the carboxyl groups anchor the surfaces of cement particles, thereby playing the role of water reducing and dispersing.
Further, the preparation method of the polycarboxylic acid concrete water reducer comprises the following steps:
(1) Adding 2-5 parts by weight of itaconic acid, 5-8 parts by weight of 4-hydroxybutyl vinyl polyoxyethylene ether and 0.01-0.02 part by weight of phenothiazine into 300-500 parts by weight of toluene, uniformly mixing, then adding 0.1-0.3 part by weight of 95-98wt% of concentrated sulfuric acid, heating to 90-110 ℃ for reacting for 4-6 hours, removing toluene by rotary evaporation, washing and drying to obtain an intermediate product;
(2) Adding 80-100 parts by weight of EPEG into 300-400 parts by weight of water, and uniformly mixing to obtain an EPEG aqueous solution; adding 0.05-0.2 weight part of sodium methacrylate sulfonate and 0.1-0.2 weight part of ascorbic acid into 20-30 weight parts of water, and uniformly mixing to obtain a mixed solution I; adding 1-3 parts by weight of acrylic acid, 0.5-1.6 parts by weight of hydrogen peroxide and 0.05-0.15 part by weight of hydrophobic acetic acid into 50-65 parts by weight of water, and uniformly mixing to obtain a mixed solution II;
(3) And adding the intermediate product into an EPEG water solution, reacting for 10-20min at 20-25 ℃, then adding the mixed solution I and the mixed solution II, keeping the temperature of 20-25 ℃ for reacting for 3-5h, and then adding a 25-30wt% sodium hydroxide water solution to adjust the pH value to 6-8, thus obtaining the polycarboxylic acid concrete water reducer.
Based on the above, the freezing resistance and the chloride ion permeation resistance of the mixed concrete are further improved, itaconic acid is adopted to treat nano titanium dioxide and carbon nanotubes to prepare itaconic acid grafted nano titanium dioxide and carbon nanotubes, and the itaconic acid grafted nano titanium dioxide and carbon nanotubes are mixed with EPEG and acrylic acid to prepare the polycarboxylic acid concrete water reducer through free radical polymerization under the normal temperature condition. Therefore, in order to improve the freezing resistance of the mixed concrete, the inventor adopts itaconic acid to perform the reaction on nano titanium dioxide and carbonThe nano tube is treated to prepare itaconic acid grafted nano titanium dioxide and carbon nano tube, and the itaconic acid grafted nano titanium dioxide and carbon nano tube are mixed with EPEG and acrylic acid to perform free radical polymerization under normal temperature condition to prepare the polycarboxylic acid concrete water reducer. The polycarboxylic acid concrete water reducer improves the frost resistance and chloride ion permeation resistance of concrete in the use process. The possible reasons for this are: (1) The nano titanium dioxide and the carbon nano tube have good nano size effect, play a role in connection and filling in concrete, refine the pore structure of concrete pairs, form an effective interface transition structure, and simultaneously generate needle-shaped products in the concrete, thereby improving the toughening effect of the concrete, further improving the frost resistance and chloride ion permeation resistance of the concrete and improving the mechanical property; (2) The charge density and the adsorption groups are increased by introducing itaconic acid grafted nano titanium dioxide and carbon nano tubes, the polycarboxylic acid concrete water reducer contains a large amount of carboxyl groups, and the carboxyl groups and positively charged C3A are electrostatically adsorbed or pass through Ca 2+ The bridging adsorption on the mineral surface plays a role in dispersing cement, improving the water reducing rate and simultaneously improving the phenomenon of the nano material caused by agglomeration. (3) The synergistic effect of the nano titanium dioxide, the carbon nano tube and the fly ash and mineral powder effectively improves the pore structure of the concrete, reduces the porosity, and simultaneously grafts Ca (OH) generated by the hydration of the itaconic acid grafted nano titanium dioxide, the carbon nano tube and the water in the concrete 2 The combination further improves the frost resistance and chloride ion permeation resistance of the concrete and improves the mechanical property.
Further, the preparation method of the polycarboxylic acid concrete water reducer comprises the following steps:
(1) Adding 2-5 parts by weight of itaconic acid, 5-8 parts by weight of 4-hydroxybutyl vinyl polyoxyethylene ether and 0.01-0.02 part by weight of phenothiazine into 300-500 parts by weight of toluene, uniformly mixing, then adding 0.1-0.3 part by weight of 95-98wt% of concentrated sulfuric acid, heating to 90-110 ℃ for reacting for 4-6 hours, removing toluene by rotary evaporation, washing and drying to obtain an intermediate product;
(2) Adding 80-100 parts by weight of EPEG into 300-400 parts by weight of water, and uniformly mixing to obtain an EPEG aqueous solution; adding 0.05-0.2 weight part of sodium methacrylate sulfonate and 0.1-0.2 weight part of ascorbic acid into 20-30 weight parts of water, and uniformly mixing to obtain a mixed solution I; adding 3-5 parts by weight of itaconic acid modified inorganic material, 1-3 parts by weight of acrylic acid, 0.5-1.6 parts by weight of hydrogen peroxide and 0.05-0.15 part by weight of hydrophobic acetic acid into 50-65 parts by weight of water, and uniformly mixing to obtain a mixed solution II;
(3) And adding the intermediate product into an EPEG water solution, reacting for 10-20min at 20-25 ℃, then adding the mixed solution I and the mixed solution II, keeping the temperature of 20-25 ℃ for reacting for 3-5h, and then adding a 25-30wt% sodium hydroxide water solution to adjust the pH value to 6-8, thus obtaining the polycarboxylic acid concrete water reducer.
The preparation method of the itaconic acid modified inorganic material comprises the following steps: adding 3-5 parts by weight of inorganic material into 50-100 parts by weight of 8wt% sodium hydroxide aqueous solution, uniformly mixing, heating to 150-250 ℃ for reaction for 2-3 hours, centrifuging, taking precipitate, washing and drying to obtain pretreated inorganic material; adding 150-200 parts by weight of DMF (dimethyl formamide) into the pretreated inorganic material, performing ultrasonic dispersion for 20-30min, then adding 10-15 parts by weight of itaconic acid, heating to 70-80 ℃ for reaction for 2-3h, centrifuging, taking precipitate, washing and drying to obtain the itaconic acid modified inorganic material.
The inorganic material is one or two of nano titanium dioxide and carbon nano tube. Preferably, the inorganic material is formed by mixing nano titanium dioxide and carbon nano tubes according to the mass ratio of (1-3).
The invention has the beneficial effects that:
1. the invention discloses a polycarboxylic acid concrete water reducer, which is prepared by taking EPEG, acrylic acid and itaconic acid modified inorganic materials as raw materials and carrying out free radical polymerization under the normal temperature condition.
2. Compared with the prior art, the polycarboxylic acid type concrete water reducer is prepared by adopting the itaconic acid modified inorganic material as the raw material, the nano titanium dioxide and the carbon nano tube have good nano size effect, play a role in connection and filling in concrete, refine the pore structure of concrete pairs, form an effective interface transition structure, and meanwhile, the nano titanium dioxide generates needle-shaped products in the concrete, thereby improving the toughening effect of the concrete and further improving the freezing resistance and chloride ion permeation resistance of the concrete.
3. The invention discloses a polycarboxylic acid concrete water reducer, which is prepared by crosslinking itaconic acid modified 4-hydroxybutyl vinyl polyoxyethylene ether, EPEG and acrylic acid at normal temperature and free radical polymerization, wherein the polycarboxylic acid concrete water reducer with a reticular structure is prepared, the existence of the reticular structure improves the adsorption force of the polycarboxylic acid concrete water reducer and concrete, the strength and compactness of concrete are further improved, and the water reducing and dispersing effects of cement slurry are improved.
Detailed Description
Raw material sources in examples:
4-hydroxybutyl vinyl polyoxyethylene ether, VPEG-2400, jiangsu Oak chemical Co.
EPEG is ethylene glycol monovinyl polyethylene glycol ether with a molecular weight of 3000, shanghai Dong chemical Co., ltd.
The average grain diameter of the nano titanium dioxide is 20-50nm, and Jiangsu Xianfeng nano materials and technologies Co.
Carbon nanotubes, short single-walled carbon nanotubes, ID:0.8-1.6nm, OD:1-2nm, length:1-3 μm, product number: c835658, shanghai microphone Biochemical technologies Co., ltd.
Example 1
The preparation method of the polycarboxylic acid concrete water reducer comprises the following steps:
(1) Adding 100 parts by weight of EPEG into 400 parts by weight of water, and uniformly mixing to obtain an EPEG aqueous solution; adding 0.1 part by weight of sodium methacrylate sulfonate and 0.2 part by weight of ascorbic acid into 30 parts by weight of water, and uniformly mixing to obtain a mixed solution I; adding 3 parts by weight of acrylic acid, 1.6 parts by weight of 25wt% hydrogen peroxide and 0.1 part by weight of hydrophobic acetic acid into 65 parts by weight of water, and uniformly mixing to obtain a mixed solution II;
(2) Adding 5 parts by weight of 4-hydroxybutyl vinyl polyoxyethylene ether into an EPEG aqueous solution, reacting for 20min at 25 ℃, then adding the mixed solution I and the mixed solution II, keeping the temperature of 25 ℃ for reacting for 5h, and then adding a 30wt% sodium hydroxide aqueous solution to adjust the pH value to 7, thus obtaining the polycarboxylic acid concrete water reducer.
Example 2
The preparation method of the polycarboxylic acid concrete water reducer comprises the following steps:
(1) Adding 2 parts by weight of itaconic acid, 5 parts by weight of 4-hydroxybutyl vinyl polyoxyethylene ether and 0.01 part by weight of phenothiazine into 300 parts by weight of toluene, uniformly mixing, then adding 0.21 part by weight of 98wt% concentrated sulfuric acid, heating to 100 ℃ for reaction for 6 hours, removing toluene by rotary evaporation, washing and drying to obtain an intermediate product;
(2) Adding 100 parts by weight of EPEG into 400 parts by weight of water, and uniformly mixing to obtain an EPEG aqueous solution; adding 0.1 part by weight of sodium methacrylate sulfonate and 0.2 part by weight of ascorbic acid into 30 parts by weight of water, and uniformly mixing to obtain a mixed solution I; adding 3 parts by weight of acrylic acid, 1.6 parts by weight of 25wt% hydrogen peroxide and 0.1 part by weight of hydrophobic acetic acid into 65 parts by weight of water, and uniformly mixing to obtain a mixed solution II;
(3) And adding the intermediate product into an EPEG water solution, reacting for 20min at 25 ℃, then adding the mixed solution I and the mixed solution II, keeping the temperature of 25 ℃ for reacting for 5h, and then adding a 30wt% sodium hydroxide water solution to adjust the pH to 7, thus obtaining the polycarboxylic acid concrete water reducer.
Example 3
The preparation method of the polycarboxylic acid concrete water reducer comprises the following steps:
(1) Adding 2 parts by weight of itaconic acid, 5 parts by weight of 4-hydroxybutyl vinyl polyoxyethylene ether and 0.01 part by weight of phenothiazine into 300 parts by weight of toluene, uniformly mixing, then adding 0.21 part by weight of 98wt% concentrated sulfuric acid, heating to 100 ℃ for reaction for 6 hours, removing toluene by rotary evaporation, washing and drying to obtain an intermediate product;
(2) Adding 100 parts by weight of EPEG into 400 parts by weight of water, and uniformly mixing to obtain an EPEG aqueous solution; adding 0.1 part by weight of sodium methacrylate sulfonate and 0.2 part by weight of ascorbic acid into 30 parts by weight of water, and uniformly mixing to obtain a mixed solution I; adding 3 parts by weight of itaconic acid modified inorganic material, 3 parts by weight of acrylic acid, 1.6 parts by weight of 25wt% hydrogen peroxide and 0.1 part by weight of hydrophobic acetic acid into 65 parts by weight of water, and uniformly mixing to obtain a mixed solution II;
(3) And adding the intermediate product into an EPEG water solution, reacting for 20min at 25 ℃, then adding the mixed solution I and the mixed solution II, keeping the temperature of 25 ℃ for reacting for 5h, and then adding a 30wt% sodium hydroxide water solution to adjust the pH to 7, thus obtaining the polycarboxylic acid concrete water reducer.
The preparation method of the itaconic acid modified inorganic material comprises the following steps: adding 3 parts by weight of inorganic material into 50 parts by weight of 8wt% sodium hydroxide aqueous solution, uniformly mixing, heating to 150 ℃ for reaction for 3 hours, centrifuging, taking precipitate, washing and drying to obtain pretreated inorganic material; adding 150 parts by weight of DMF (dimethyl formamide) into the pretreated inorganic material, performing ultrasonic dispersion for 30min, then adding 10 parts by weight of itaconic acid, heating to 80 ℃ for reaction for 3h, centrifuging, taking precipitate, washing and drying to obtain the itaconic acid modified inorganic material.
The inorganic material is prepared by mixing nano titanium dioxide and carbon nano tubes according to a mass ratio of 1:1.
Example 4
The preparation method of the polycarboxylic acid concrete water reducer comprises the following steps:
(1) Adding 2 parts by weight of itaconic acid, 5 parts by weight of 4-hydroxybutyl vinyl polyoxyethylene ether and 0.01 part by weight of phenothiazine into 300 parts by weight of toluene, uniformly mixing, then adding 0.21 part by weight of 98wt% concentrated sulfuric acid, heating to 100 ℃ for reaction for 6 hours, removing toluene by rotary evaporation, washing and drying to obtain an intermediate product;
(2) Adding 100 parts by weight of EPEG into 400 parts by weight of water, and uniformly mixing to obtain an EPEG aqueous solution; adding 0.1 part by weight of sodium methacrylate sulfonate and 0.2 part by weight of ascorbic acid into 30 parts by weight of water, and uniformly mixing to obtain a mixed solution I; adding 3 parts by weight of itaconic acid modified inorganic material, 3 parts by weight of acrylic acid, 1.6 parts by weight of 25wt% hydrogen peroxide and 0.1 part by weight of hydrophobic acetic acid into 65 parts by weight of water, and uniformly mixing to obtain a mixed solution II;
(3) And adding the intermediate product into an EPEG water solution, reacting for 20min at 25 ℃, then adding the mixed solution I and the mixed solution II, keeping the temperature of 25 ℃ for reacting for 5h, and then adding a 30wt% sodium hydroxide water solution to adjust the pH to 7, thus obtaining the polycarboxylic acid concrete water reducer.
The preparation method of the itaconic acid modified inorganic material comprises the following steps: adding 3 parts by weight of inorganic material into 50 parts by weight of 8wt% sodium hydroxide aqueous solution, uniformly mixing, heating to 150 ℃ for reaction for 3 hours, centrifuging, taking precipitate, washing and drying to obtain pretreated inorganic material; adding 150 parts by weight of DMF (dimethyl formamide) into the pretreated inorganic material, performing ultrasonic dispersion for 30min, then adding 10 parts by weight of itaconic acid, heating to 80 ℃ for reaction for 3h, centrifuging, taking precipitate, washing and drying to obtain the itaconic acid modified inorganic material.
The inorganic material is nano titanium dioxide.
Example 5
The preparation method of the polycarboxylic acid concrete water reducer comprises the following steps:
(1) Adding 2 parts by weight of itaconic acid, 5 parts by weight of 4-hydroxybutyl vinyl polyoxyethylene ether and 0.01 part by weight of phenothiazine into 300 parts by weight of toluene, uniformly mixing, then adding 0.21 part by weight of 98wt% concentrated sulfuric acid, heating to 100 ℃ for reaction for 6 hours, removing toluene by rotary evaporation, washing and drying to obtain an intermediate product;
(2) Adding 100 parts by weight of EPEG into 400 parts by weight of water, and uniformly mixing to obtain an EPEG aqueous solution; adding 0.1 part by weight of sodium methacrylate sulfonate and 0.2 part by weight of ascorbic acid into 30 parts by weight of water, and uniformly mixing to obtain a mixed solution I; adding 3 parts by weight of itaconic acid modified inorganic material, 3 parts by weight of acrylic acid, 1.6 parts by weight of 25wt% hydrogen peroxide and 0.1 part by weight of hydrophobic acetic acid into 65 parts by weight of water, and uniformly mixing to obtain a mixed solution II;
(3) And adding the intermediate product into an EPEG water solution, reacting for 20min at 25 ℃, then adding the mixed solution I and the mixed solution II, keeping the temperature of 25 ℃ for reacting for 5h, and then adding a 30wt% sodium hydroxide water solution to adjust the pH to 7, thus obtaining the polycarboxylic acid concrete water reducer.
The preparation method of the itaconic acid modified inorganic material comprises the following steps: adding 3 parts by weight of inorganic material into 50 parts by weight of 8wt% sodium hydroxide aqueous solution, uniformly mixing, heating to 150 ℃ for reaction for 3 hours, centrifuging, taking precipitate, washing and drying to obtain pretreated inorganic material; adding 150 parts by weight of DMF (dimethyl formamide) into the pretreated inorganic material, performing ultrasonic dispersion for 30min, then adding 10 parts by weight of itaconic acid, heating to 80 ℃ for reaction for 3h, centrifuging, taking precipitate, washing and drying to obtain the itaconic acid modified inorganic material.
The inorganic material is carbon nano tube.
Example 6
The preparation method of the polycarboxylic acid concrete water reducer comprises the following steps:
(1) Adding 2 parts by weight of itaconic acid, 5 parts by weight of 4-hydroxybutyl vinyl polyoxyethylene ether and 0.01 part by weight of phenothiazine into 300 parts by weight of toluene, uniformly mixing, then adding 0.21 part by weight of 98wt% concentrated sulfuric acid, heating to 100 ℃ for reaction for 6 hours, removing toluene by rotary evaporation, washing and drying to obtain an intermediate product;
(2) Adding 100 parts by weight of EPEG into 400 parts by weight of water, and uniformly mixing to obtain an EPEG aqueous solution; adding 0.1 part by weight of sodium methacrylate sulfonate and 0.2 part by weight of ascorbic acid into 30 parts by weight of water, and uniformly mixing to obtain a mixed solution I; adding 3 parts by weight of inorganic material, 3 parts by weight of acrylic acid, 1.6 parts by weight of 25wt% hydrogen peroxide and 0.1 part by weight of hydrophobic acetic acid into 65 parts by weight of water, and uniformly mixing to obtain a mixed solution II;
(3) And adding the intermediate product into an EPEG water solution, reacting for 20min at 25 ℃, then adding the mixed solution I and the mixed solution II, keeping the temperature of 25 ℃ for reacting for 5h, and then adding a 30wt% sodium hydroxide water solution to adjust the pH to 7, thus obtaining the polycarboxylic acid concrete water reducer.
The inorganic material is prepared by mixing nano titanium dioxide and carbon nano tubes according to a mass ratio of 1:1.
Test example 1
The polycarboxylic acid type concrete water reducing agent prepared in examples 1 to 6 was tested.
The concrete mixture ratio is as follows: 370kg of P.O42.5R cement, 60kg of fly ash, 60kg of mineral powder, 30kg of silica fume, 610kg of sand (fineness modulus is 2.5), 1000kg of stone (5-25 mm continuous graded broken stone), 110kg of water and 14.8kg of water reducer (accounting for 4 percent of the cement).
And (3) carrying out a freeze-thawing cycle comparison test on the concrete after standard curing for 28d and with the dimensions of 100mm multiplied by 100mm, and detecting the mass loss rate and the relative dynamic elastic modulus of the concrete after 180 times of freeze-thawing cycles by referring to a quick freezing method in GB/T50082-2009 Standard for test method of the long-term performance and durability of common concrete.
Table 1 results of test for anti-freeze properties of concrete
By comparing example 2 with example 3, it was found that the concrete containing the polycarboxylic acid type concrete water reducing agent prepared in example 3 was thrown away to have good antifreeze performance after 180 times of freeze thawing cycles, which is probably because: (1) The nano titanium dioxide and the carbon nano tube have good nano size effect, play a role in connection and filling in concrete, refine the pore structure of concrete pairs, form an effective interface transition structure, simultaneously generate needle-shaped products in the concrete by the nano titanium dioxide, improve the toughening effect of the concrete, simultaneously generate crystal nucleus and high activity effect, accelerate the agglomeration compact growth of induced gel and consume minerals of hydration reaction, improve the gel structure, further improve the frost resistance and chloride ion permeation resistance of the concrete and improve the mechanical property; (2) The charge density and the adsorption groups are increased by introducing itaconic acid grafted nano titanium dioxide and carbon nano tubes, the polycarboxylic acid concrete water reducer contains a large amount of carboxyl groups, and the carboxyl groups and positively charged C3A are electrostatically adsorbed or pass through Ca 2+ The bridging adsorption on the mineral surface plays a role in dispersing cement, improving the water reducing rate and simultaneously improving the phenomenon of the nano material caused by agglomeration. (3) The synergistic effect of the nano titanium dioxide, the carbon nano tube and the fly ash and mineral powder effectively improves the pore structure of the concrete, reduces the porosity, and simultaneously grafts Ca (OH) generated by the hydration of the itaconic acid grafted nano titanium dioxide, the carbon nano tube and the water in the concrete 2 The combination further improves the frost resistance and chloride ion permeation resistance of the concrete and improves the mechanical property.
Test example 2
Chlorine ion erosion resistance test: the polycarboxylic acid type concrete water reducing agent prepared in examples 1 to 6 was tested.
The concrete mixture ratio is as follows: 370kg of P.O42.5R cement, 60kg of fly ash, 60kg of mineral powder, 30kg of silica fume, 610kg of sand (fineness modulus is 2.5), 1000kg of stone (5-25 mm continuous graded broken stone), 110kg of water and 14.8kg of water reducer (accounting for 4 percent of the cement).
The test method for testing each test item of the anti-chloride ion permeation grade is carried out by referring to the quick chloride ion migration coefficient method in GB/T50082-2009 Standard for test methods for common concrete long-term Performance and durability.
The specific test method comprises the following steps: first, the standard curing is dimensioned asThe method comprises the steps of wiping and measuring the diameter and the height of a test block, then vacuum-preserving water in saturated calcium hydroxide solution for 4 hours and soaking for l8 hours at normal pressure, then wiping and installing the test block in a rubber sleeve, smearing vaseline on the side surface to ensure sealing and impermeability, installing test equipment, pouring prepared cathode and anode solutions into a specified position, turning on a power supply, debugging the equipment, recording initial voltage, current, anode solution temperature and the like, recording final current and temperature again after the test is finished, disassembling the device, cutting the test block, measuring the penetration depth by a chromogenic method, and calculating chloride ion diffusion coefficient.
TABLE 2 results of chlorine ion erosion resistance test of concrete
| Diffusion coefficient of chloride ion (10) -12 m -2 /s) | |
| Example 1 | 4.86 |
| Example 2 | 3.42 |
| Example 3 | 2.03 |
| Example 4 | 2.61 |
| Example 5 | 2.48 |
| Example 6 | 3.10 |
By comparing example 1 with example 2, it was found that the concrete containing the polycarboxylic acid type concrete water reducing agent prepared in example 2 was thrown away to have good antifreeze performance after 180 times of freeze thawing cycles, which is probably because: the itaconic acid modified 4-hydroxybutyl vinyl polyoxyethylene ether is introduced, and is crosslinked with EPEG and acrylic acid at normal temperature, and free radical polymerization is carried out to prepare the polycarboxylic acid concrete water reducer with a reticular structure, the existence of the reticular structure improves the adsorption force of the polycarboxylic acid concrete water reducer and concrete, the strength and compactness of the concrete are further improved, and the penetration erosion of chloride ions is greatly reduced by the concrete with compact structure.
Claims (6)
1. The preparation method of the polycarboxylic acid concrete water reducer is characterized by comprising the following steps of: the method comprises the following steps:
(1) Adding itaconic acid, 4-hydroxybutyl vinyl polyoxyethylene ether and phenothiazine into toluene, uniformly mixing, adding concentrated sulfuric acid for mixing reaction, removing toluene by rotary evaporation, washing and drying to obtain an intermediate product;
(2) Adding EPEG into water, and uniformly mixing to obtain an EPEG aqueous solution; adding sodium methacrylate and ascorbic acid into water, and uniformly mixing to obtain a mixed solution I; adding acrylic acid, hydrogen peroxide and thioglycollic acid into water, and uniformly mixing to obtain a mixed solution II;
(3) And adding the intermediate product into an EPEG water solution for reaction, then adding the mixed solution I and the mixed solution II for reaction, and then adding a sodium hydroxide water solution for regulating the pH value to obtain the polycarboxylic acid concrete water reducer.
2. The method for preparing the polycarboxylic acid type concrete water reducing agent according to claim 1, which is characterized in that: the method comprises the following steps:
(1) Adding 2-5 parts by weight of itaconic acid, 5-8 parts by weight of 4-hydroxybutyl vinyl polyoxyethylene ether and 0.01-0.02 part by weight of phenothiazine into 300-500 parts by weight of toluene, uniformly mixing, then adding 0.1-0.3 part by weight of 95-98wt% of concentrated sulfuric acid, heating to 90-110 ℃ for reacting for 4-6 hours, removing toluene by rotary evaporation, washing and drying to obtain an intermediate product;
(2) Adding 80-100 parts by weight of EPEG into 300-400 parts by weight of water, and uniformly mixing to obtain an EPEG aqueous solution; adding 0.05-0.2 weight part of sodium methacrylate sulfonate and 0.1-0.2 weight part of ascorbic acid into 20-30 weight parts of water, and uniformly mixing to obtain a mixed solution I; adding 1-3 parts by weight of acrylic acid, 0.5-1.6 parts by weight of hydrogen peroxide and 0.05-0.15 part by weight of hydrophobic acetic acid into 50-65 parts by weight of water, and uniformly mixing to obtain a mixed solution II;
(3) And adding the intermediate product into an EPEG water solution, reacting for 10-20min at 20-25 ℃, then adding the mixed solution I and the mixed solution II, keeping the temperature of 20-25 ℃ for reacting for 3-5h, and then adding a 25-30wt% sodium hydroxide water solution to adjust the pH value to 6-8, thus obtaining the polycarboxylic acid concrete water reducer.
3. The method for preparing the polycarboxylic acid type concrete water reducing agent according to claim 2, characterized in that: the method comprises the following steps:
(1) Adding 2-5 parts by weight of itaconic acid, 5-8 parts by weight of 4-hydroxybutyl vinyl polyoxyethylene ether and 0.01-0.02 part by weight of phenothiazine into 300-500 parts by weight of toluene, uniformly mixing, then adding 0.1-0.3 part by weight of 95-98wt% of concentrated sulfuric acid, heating to 90-110 ℃ for reacting for 4-6 hours, removing toluene by rotary evaporation, washing and drying to obtain an intermediate product;
(2) Adding 80-100 parts by weight of EPEG into 300-400 parts by weight of water, and uniformly mixing to obtain an EPEG aqueous solution; adding 0.05-0.2 weight part of sodium methacrylate sulfonate and 0.1-0.2 weight part of ascorbic acid into 20-30 weight parts of water, and uniformly mixing to obtain a mixed solution I; adding 3-5 parts by weight of itaconic acid modified inorganic material, 1-3 parts by weight of acrylic acid, 0.5-1.6 parts by weight of hydrogen peroxide and 0.05-0.15 part by weight of hydrophobic acetic acid into 50-65 parts by weight of water, and uniformly mixing to obtain a mixed solution II;
(3) And adding the intermediate product into an EPEG water solution, reacting for 10-20min at 20-25 ℃, then adding the mixed solution I and the mixed solution II, keeping the temperature of 20-25 ℃ for reacting for 3-5h, and then adding a 25-30wt% sodium hydroxide water solution to adjust the pH value to 6-8, thus obtaining the polycarboxylic acid concrete water reducer.
4. The method for preparing the polycarboxylic acid type concrete water reducing agent according to claim 3, wherein: the preparation method of the itaconic acid modified inorganic material comprises the following steps: adding inorganic materials into a sodium hydroxide aqueous solution, uniformly mixing, heating to react, centrifuging to obtain precipitate, washing and drying to obtain pretreated inorganic materials; adding the pretreated inorganic material into DMF for ultrasonic dispersion, then adding itaconic acid, reacting, centrifuging to obtain precipitate, washing and drying to obtain the itaconic acid modified inorganic material.
5. The method for preparing the polycarboxylic acid type concrete water reducing agent according to claim 4, which is characterized in that: the inorganic material is one or two of nano titanium dioxide and carbon nano tube.
6. The polycarboxylic acid concrete water reducer is characterized in that: the method for preparing the polycarboxylic acid concrete water reducer is characterized by comprising the steps of 1-5.
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