Polycarboxylate water reducer containing nanomaterials and preparation method thereof

Abstract

The present invention relates to the technical field of concrete admixtures and discloses a polycarboxylate water-reducing agent containing nanomaterials and a preparation method thereof. The present invention comprises adding solution A, alkenyl-modified silane chitosan, water, ammonium chloride, and ferrous sulfate to a reactor, and then adding a sodium persulfate initiator solution E, a mercaptoethanol reducing agent solution C, and a thioglycolic acid chain transfer agent solution D under stirring to initiate a polymerization reaction. Solution B is then added dropwise to the reaction mixture. After the addition is complete, the reaction is carried out, the product is cooled to room temperature, and the pH value is adjusted to neutral with an alkaline solution to obtain the polycarboxylate water-reducing agent containing nanomaterials. The chitosan in the alkenyl-modified silane chitosan can reduce the diffusion coefficient of chloride ions, improve the impermeability and density of concrete, and also improve the durability of concrete. The siloxane groups therein also improve the durability of concrete.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete admixtures, in particular to a polycarboxylate water reducer containing nanomaterials and a preparation method thereof. Background Art

[0002] Concrete is an artificial stone made of gel material, aggregate, water and admixtures in a certain proportion. It has the characteristics of abundant raw materials, low price and simple production process. However, during use, some admixtures need to be added to meet performance requirements.

[0003] For example, patent CN107189021A discloses a polycarboxylic acid water reducer and its preparation method. This invention can avoid the problem of low efficiency caused by using a reducing agent at lower temperatures. At the same time, it can shorten the addition time, shorten the production cycle, reduce energy consumption, and reduce production costs; however, its performance needs to be improved. Summary of the Invention

[0004] (1) Technical problems solved

[0005] In view of the shortcomings of the prior art, the present invention provides a polycarboxylate water-reducing agent containing nanomaterials and a preparation method thereof, which improves the durability and compressive strength of concrete.

[0006] (2) Technical solution

[0007] To achieve the above object, the present invention provides the following technical solution: a polycarboxylate water-reducing agent containing nanomaterials, comprising the following components by weight: 5-9 parts by weight of alkenyl-modified silane chitosan, 150-220 parts by weight of isopentenol polyoxyethylene ether, 35-60 parts by weight of methyl acrylate, 40-70 parts by weight of diethylene glycol monoacrylate, 5-8 parts by weight of ammonium chloride, 3-4 parts by weight of ferrous sulfate, 1-2 parts by weight of mercaptoethanol reducing agent, 0.8-1.3 parts by weight of thioglycolic acid chain transfer agent, 2-3 parts by weight of sodium persulfate initiator, and 80-100 parts by weight of water.

[0008] Preferably, the preparation method of the alkenyl-modified silane chitosan is:

[0009] (1) Allyl glycidyl ether, tetrahydrofuran solvent and chloroplatinic acid are added to the reactor, activated at 45-60°C for 30-50 minutes, and then 1,1,3,3-tetramethyldisiloxane is added dropwise for 50-65 minutes. The reaction is continued at 55-65°C for 4-7 hours. After the reaction is completed, it is cooled to room temperature, activated carbon adsorbent is added, ultrasonically shaken for 30-40 minutes, the catalyst chloroplatinic acid is removed, filtered, and rotary evaporated to obtain epoxy-modified siloxane;

[0010] (2) Add 6-10 parts by weight of chitosan to dimethyl sulfoxide solvent to dissolve it, stir it evenly, add 5-8 parts by weight of 2,3-epoxypropyltrimethylammonium chloride at constant pressure, react at 70-90°C, wash with anhydrous ethanol after the reaction, dry, dialyze, and concentrate to obtain quaternized chitosan;

[0011] (3) adding 6-10 parts by weight of quaternized chitosan to an acetic acid solution, stirring evenly, and then adding 10-16 parts by weight of epoxy-modified siloxane thereto, ultrasonically shaking at 50-60°C, cooling to room temperature, adding hydrochloric acid dropwise until neutral, washing, and drying to obtain modified chitosan;

[0012] (4) Add 4-7 parts by weight of modified chitosan and 6-15 parts by weight of acrylic acid to N,N-dimethylformamide solvent, stir evenly, then add 0.2-0.3 parts by weight of p-toluenesulfonic acid catalyst, react for 10-13 hours, and then distill under reduced pressure, filter and dry to obtain alkenyl-modified silane chitosan.

[0013] Preferably, the mass ratio of allyl glycidyl ether, chloroplatinic acid, and 1,1,3,3-tetramethyldisiloxane in (1) is 1:0.01-0.03:1.1-1.2.

[0014] Preferably, the reaction time in (2) is 6-8 hours.

[0015] Preferably, the ultrasonic oscillation time in (3) is 30-40 minutes.

[0016] Preferably, the reaction temperature in (4) is 85-110°C.

[0017] Preferably, the preparation method of the polycarboxylate water-reducing agent containing nanomaterials is:

[0018] S1. Dissolve isopentanol polyoxyethylene ether in deionized water and stir to obtain solution A;

[0019] S2. Methyl acrylate and diethylene glycol monoacrylate were dissolved in deionized water and stirred to obtain a solution B;

[0020] S3. The mercaptoethanol reducing agent, thioglycolic acid chain transfer agent and sodium persulfate initiator were dissolved in deionized water and stirred to obtain solutions C, D, and E, respectively;

[0021] S4. Add solution A, alkenyl-modified silane chitosan, water, ammonium chloride, and ferrous sulfate to a reactor, and add sodium persulfate initiator solution E, mercaptoethanol reducing agent solution C, and thioglycolic acid chain transfer agent solution D under stirring to initiate a polymerization reaction, and then add solution B dropwise thereto; after the dropwise addition is completed, react at 40-60°C for 2-6 hours, cool the product to room temperature, and then adjust the pH value to neutral with alkaline solution to obtain a polycarboxylic acid water reducer containing nanomaterials.

[0022] (3) Beneficial technical effects

[0023] The invention comprises the following steps: adding solution A, alkenyl-modified silane chitosan, water, ammonium chloride and ferrous sulfate into a reactor, and adding a sodium persulfate initiator solution E, a mercaptoethanol reducing agent solution C and a thioglycolic acid chain transfer agent solution D under stirring conditions to initiate a polymerization reaction, and then dropwise adding solution B thereto; after the dropwise addition is completed, reacting, cooling the product to room temperature, and then adjusting the pH value to neutral with an alkali solution to obtain a polycarboxylate water reducer containing nanomaterials.

[0024] The chitosan in alkenyl-modified silane chitosan can reduce the diffusion coefficient of chloride ions, improve the impermeability and density of concrete, and also improve the durability of concrete; the siloxane groups therein also improve the durability of concrete; the quaternary ammonium salt groups can react with the negative charges in the clay to form a protective film that prevents water molecules and water-reducing agent molecules from entering the clay. This effect can effectively reduce the clay's adsorption of polycarboxylic acid water-reducing agent, thereby reducing the dosage of polycarboxylic acid admixture and ensuring good performance of concrete. DETAILED DESCRIPTION

[0025] Example 1

[0026] A polycarboxylate water-reducing agent containing nanomaterials comprises the following components by weight: 5 parts by weight of alkenyl-modified silane chitosan, 150 parts by weight of isopentanol polyoxyethylene ether, 35 parts by weight of methyl acrylate, 40 parts by weight of diethylene glycol monoacrylate, 5 parts by weight of ammonium chloride, 3 parts by weight of ferrous sulfate, 1 part by weight of mercaptoethanol reducing agent, 0.8 parts by weight of thioglycolic acid chain transfer agent, 2 parts by weight of sodium persulfate initiator, and 80 parts by weight of water.

[0027] The preparation method of the alkenyl-modified silane chitosan is as follows:

[0028] (1) Allyl glycidyl ether, tetrahydrofuran solvent and chloroplatinic acid were added to the reactor, activated at 45 ° C for 30 minutes, and then 1,1,3,3-tetramethyldisiloxane was added dropwise, wherein the mass ratio of allyl glycidyl ether, chloroplatinic acid and 1,1,3,3-tetramethyldisiloxane was 1:0.01:1.1, and the addition time was 50 minutes. The reaction was continued at 55 ° C for 4 hours. After the reaction was completed, it was cooled to room temperature, activated carbon adsorbent was added, ultrasonic vibration was carried out for 30 minutes, the catalyst chloroplatinic acid was removed, and the reaction was filtered and rotary evaporated to obtain epoxy-modified siloxane;

[0029] (2) 6 parts by weight of chitosan was added to dimethyl sulfoxide solvent to dissolve the chitosan, and after stirring evenly, 5 parts by weight of 2,3-epoxypropyltrimethylammonium chloride was added at a constant pressure, and the mixture was reacted at 70°C for 6 hours. After the reaction, the mixture was washed with anhydrous ethanol, dried, dialyzed, and concentrated to obtain quaternized chitosan;

[0030] (3) 6 parts by weight of quaternized chitosan was added to the acetic acid solution, stirred evenly, and then 10 parts by weight of epoxy-modified siloxane was added thereto. The mixture was ultrasonically shaken at 50°C for 30 minutes, cooled to room temperature, and hydrochloric acid was added dropwise to neutralize the mixture. The mixture was washed and dried to obtain modified chitosan.

[0031] (4) 4 parts by weight of modified chitosan and 6 parts by weight of acrylic acid were added to N,N-dimethylformamide solvent and stirred evenly. Then, 0.2 parts by weight of p-toluenesulfonic acid catalyst was added thereto. The reaction was carried out at 85°C for 10 hours. After the reaction, the mixture was distilled under reduced pressure, filtered and dried to obtain alkenyl-modified silane chitosan.

[0032] The preparation method of the polycarboxylate water-reducing agent containing nanomaterials is as follows:

[0033] S1. Dissolve isopentanol polyoxyethylene ether in deionized water and stir to obtain solution A;

[0034] S2. Methyl acrylate and diethylene glycol monoacrylate were dissolved in deionized water and stirred to obtain a solution B;

[0035] S3. The mercaptoethanol reducing agent, thioglycolic acid chain transfer agent and sodium persulfate initiator were dissolved in deionized water and stirred to obtain solutions C, D, and E, respectively;

[0036] S4. Solution A, alkenyl-modified silane chitosan, water, ammonium chloride, and ferrous sulfate are added to a reactor, and sodium persulfate initiator solution E, mercaptoethanol reducing agent solution C, and thioglycolic acid chain transfer agent solution D are added under stirring to initiate a polymerization reaction, and then solution B is added dropwise thereto; after the dropwise addition is completed, the reaction is carried out at 40°C for 2 hours, the product is cooled to room temperature, and then the pH value is adjusted to neutral with alkaline solution to obtain a polycarboxylic acid water reducer containing nanomaterials.

[0037] Example 2

[0038] A polycarboxylate water-reducing agent containing nanomaterials comprises the following components by weight: 9 parts by weight of alkenyl-modified silane chitosan, 220 parts by weight of isopentanol polyoxyethylene ether, 60 parts by weight of methyl acrylate, 70 parts by weight of diethylene glycol monoacrylate, 8 parts by weight of ammonium chloride, 4 parts by weight of ferrous sulfate, 2 parts by weight of mercaptoethanol reducing agent, 1.3 parts by weight of thioglycolic acid chain transfer agent, 3 parts by weight of sodium persulfate initiator, and 100 parts by weight of water.

[0039] The preparation method of the alkenyl-modified silane chitosan is as follows:

[0040] (1) Allyl glycidyl ether, tetrahydrofuran solvent and chloroplatinic acid were added to the reactor, activated at 60 ° C for 50 minutes, and then 1,1,3,3-tetramethyldisiloxane was added dropwise, wherein the mass ratio of allyl glycidyl ether, chloroplatinic acid and 1,1,3,3-tetramethyldisiloxane was 1:0.03:1.2, and the addition time was 65 minutes. The reaction was continued at 65 ° C for 7 hours. After the reaction was completed, it was cooled to room temperature, activated carbon adsorbent was added, ultrasonic vibration was carried out for 40 minutes, the catalyst chloroplatinic acid was removed, and the reaction was filtered and rotary evaporated to obtain epoxy-modified siloxane;

[0041] (2) 10 parts by weight of chitosan was added to dimethyl sulfoxide solvent to dissolve the chitosan, and after stirring evenly, 8 parts by weight of 2,3-epoxypropyltrimethylammonium chloride was added at a constant pressure, and the mixture was reacted at 90°C for 8 hours. After the reaction, the mixture was washed with anhydrous ethanol, dried, dialyzed, and concentrated to obtain quaternized chitosan;

[0042] (3) Add 10 parts by weight of quaternized chitosan to the acetic acid solution, stir evenly, and then add 16 parts by weight of epoxy-modified siloxane. Ultrasonicate at 60°C for 40 minutes, cool to room temperature, add hydrochloric acid dropwise until neutral, wash and dry to obtain modified chitosan.

[0043] (4) 7 parts by weight of modified chitosan and 15 parts by weight of acrylic acid were added to N,N-dimethylformamide solvent and stirred evenly. Then, 0.3 parts by weight of p-toluenesulfonic acid catalyst was added thereto. The reaction was carried out at 110°C for 13 hours. After the reaction, the mixture was distilled under reduced pressure, filtered and dried to obtain alkenyl-modified silane chitosan.

[0044] The preparation method of the polycarboxylate water-reducing agent containing nanomaterials is as follows:

[0045] S1. Dissolve isopentanol polyoxyethylene ether in deionized water and stir to obtain solution A;

[0046] S2. Methyl acrylate and diethylene glycol monoacrylate were dissolved in deionized water and stirred to obtain a solution B;

[0047] S3. The mercaptoethanol reducing agent, thioglycolic acid chain transfer agent and sodium persulfate initiator were dissolved in deionized water and stirred to obtain solutions C, D, and E, respectively;

[0048] S4. Solution A, alkenyl-modified silane chitosan, water, ammonium chloride, and ferrous sulfate are added to a reactor, and sodium persulfate initiator solution E, mercaptoethanol reducing agent solution C, and thioglycolic acid chain transfer agent solution D are added under stirring to initiate a polymerization reaction, and then solution B is added dropwise thereto; after the dropwise addition is completed, the reaction is carried out at 60°C for 6 hours, the product is cooled to room temperature, and then the pH value is adjusted to neutral with alkaline solution to obtain a polycarboxylic acid water reducer containing nanomaterials.

[0049] Example 3

[0050] A polycarboxylate water-reducing agent containing nanomaterials comprises the following components by weight: 8 parts by weight of alkenyl-modified silane chitosan, 200 parts by weight of isopentanol polyoxyethylene ether, 55 parts by weight of methyl acrylate, 60 parts by weight of diethylene glycol monoacrylate, 7 parts by weight of ammonium chloride, 3 parts by weight of ferrous sulfate, 1 part by weight of mercaptoethanol reducing agent, 0.9 parts by weight of thioglycolic acid chain transfer agent, 2 parts by weight of sodium persulfate initiator, and 90 parts by weight of water.

[0051] The preparation method of the alkenyl-modified silane chitosan is as follows:

[0052] (1) Allyl glycidyl ether, tetrahydrofuran solvent and chloroplatinic acid were added to the reactor, activated at 55 ° C for 40 minutes, and then 1,1,3,3-tetramethyldisiloxane was added dropwise, wherein the mass ratio of allyl glycidyl ether, chloroplatinic acid and 1,1,3,3-tetramethyldisiloxane was 1:0.02:1.1, and the addition time was 55 minutes. The reaction was continued at 60 ° C for 6 hours. After the reaction was completed, it was cooled to room temperature, activated carbon adsorbent was added, ultrasonic vibration was carried out for 35 minutes, the catalyst chloroplatinic acid was removed, and the reaction was filtered and rotary evaporated to obtain epoxy-modified siloxane;

[0053] (2) 8 parts by weight of chitosan was added to dimethyl sulfoxide solvent to dissolve the chitosan, and after stirring evenly, 6 parts by weight of 2,3-epoxypropyltrimethylammonium chloride was added at a constant pressure, and the mixture was reacted at 80°C for 7 hours. After the reaction, the mixture was washed with anhydrous ethanol, dried, dialyzed, and concentrated to obtain quaternized chitosan;

[0054] (3) 8 parts by weight of quaternized chitosan was added to the acetic acid solution, stirred evenly, and then 13 parts by weight of epoxy-modified siloxane was added thereto. The mixture was ultrasonically shaken at 55°C for 35 minutes, cooled to room temperature, and hydrochloric acid was added dropwise to neutralize the mixture. The mixture was washed and dried to obtain modified chitosan.

[0055] (4) 6 parts by weight of modified chitosan and 8 parts by weight of acrylic acid were added to N,N-dimethylformamide solvent and stirred evenly. Then, 0.2 parts by weight of p-toluenesulfonic acid catalyst was added thereto. The mixture was reacted at 100°C for 12 hours. After the reaction, the mixture was distilled under reduced pressure, filtered and dried to obtain alkenyl-modified silane chitosan.

[0056] The preparation method of the polycarboxylate water-reducing agent containing nanomaterials is as follows:

[0057] S1. Dissolve isopentanol polyoxyethylene ether in deionized water and stir to obtain solution A;

[0058] S2. Methyl acrylate and diethylene glycol monoacrylate were dissolved in deionized water and stirred to obtain a solution B;

[0059] S3. The mercaptoethanol reducing agent, thioglycolic acid chain transfer agent and sodium persulfate initiator were dissolved in deionized water and stirred to obtain solutions C, D, and E, respectively;

[0060] S4. Solution A, alkenyl-modified silane chitosan, water, ammonium chloride, and ferrous sulfate are added to a reactor, and sodium persulfate initiator solution E, mercaptoethanol reducing agent solution C, and thioglycolic acid chain transfer agent solution D are added under stirring to initiate a polymerization reaction, and then solution B is added dropwise thereto; after the dropwise addition is completed, the reaction is carried out at 50°C for 4 hours, the product is cooled to room temperature, and then the pH value is adjusted to neutral with alkaline solution to obtain a polycarboxylic acid water reducer containing nanomaterials.

[0061] Comparative Example 1

[0062] Compared with Example 3, this comparative example differs in that no alkenyl-modified silane chitosan is added.

[0063] Performance Testing

[0064] At 20-35° C., medium sand and gravel are poured into a mixer and stirred for 1-2 minutes. Fly ash and cement are then added thereto and stirred continuously for 5-8 minutes. A polycarboxylate water-reducer containing nanomaterials is poured into water and stirred evenly. Water is then slowly added to the stirred mixture and stirred for 3-5 minutes. After the mixture is stirred, it is cast into a mold and cured at room temperature for 20-24 hours. The mold is removed after forming and then cured in a standard curing room for 30-35 days to obtain a 150 mm*150 mm*150 mm concrete specimen; wherein the mass ratio of medium sand, gravel, fly ash, cement, water, and polycarboxylate water-reducer containing nanomaterials is 1.2-1.4:2.3-2.8:0.5-0.6:1:0.4-0.6:0.04-0.06.

[0065] The concrete specimens prepared in Example 13 and Comparative Example 1 were tested for compressive strength, flexural strength, and chloride ion diffusion coefficient. The compressive strength and flexural strength tests were conducted in accordance with GB / T 50081 (2002) "Standard for Test Methods for Mechanical Properties of Ordinary Concrete," and the chloride ion diffusion coefficient test was conducted in accordance with GB / T 50082 (2009) "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete." Specific test results are shown in Table 1. Furthermore, according to GB / T 50476 (2008) "Code for Durability Design of Concrete Structures," the chloride ion diffusion coefficient of a Class E structure with a design life of 100 years should be less than 4×10 12 m 2 / s.

[0066] Table 1: Performance tests.

[0067]

[0068] As can be seen from Table 1, Examples 1-3 of the present invention have better compressive strength and flexural strength than Comparative Example 1, and also have better resistance to chloride ion corrosion.

[0069] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A polycarboxylate water-reducing agent containing nanomaterials, characterized in that: The invention comprises the following components by weight: 5-9 parts by weight of alkenyl-modified silane chitosan, 150-220 parts by weight of isopentenol polyoxyethylene ether, 35-60 parts by weight of methyl acrylate, 40-70 parts by weight of diethylene glycol monoacrylate, 5-8 parts by weight of ammonium chloride, 3-4 parts by weight of ferrous sulfate, 1-2 parts by weight of mercaptoethanol reducing agent, 0.8-1.3 parts by weight of thioglycolic acid chain transfer agent, 2-3 parts by weight of sodium persulfate initiator, and 80-100 parts by weight of water; The preparation method of the alkenyl-modified silane chitosan is as follows: (1) Allyl glycidyl ether, tetrahydrofuran solvent and chloroplatinic acid are added to a reactor, activated at 45-60°C for 30-50 minutes, and then 1,1,3,3-tetramethyldisiloxane is added dropwise for 50-65 minutes. The reaction is continued at 55-65°C for 4-7 hours. After the reaction is completed, the reaction is cooled to room temperature, activated carbon adsorbent is added, ultrasonic vibration is carried out for 30-40 minutes, the catalyst chloroplatinic acid is removed, and the reaction is filtered and rotary evaporated to obtain epoxy-modified siloxane; (2) adding 6-10 parts by weight of chitosan to dimethyl sulfoxide solvent to dissolve the chitosan, stirring evenly, adding 5-8 parts by weight of 2,3-epoxypropyltrimethylammonium chloride at a constant pressure, reacting at 70-90° C., washing with anhydrous ethanol after the reaction, drying, dialyzing, and concentrating to obtain quaternized chitosan; (3) adding 6-10 parts by weight of quaternized chitosan to an acetic acid solution, stirring uniformly, and then adding 10-16 parts by weight of epoxy-modified siloxane thereto, ultrasonically shaking at 50-60° C., cooling to room temperature, adding hydrochloric acid dropwise until neutral, washing, and drying to obtain modified chitosan; (4) adding 4-7 parts by weight of modified chitosan and 6-15 parts by weight of acrylic acid to N,N-dimethylformamide solvent, stirring evenly, then adding 0.2-0.3 parts by weight of p-toluenesulfonic acid catalyst thereto, reacting for 10-13 hours, and then distilling under reduced pressure, filtering and drying to obtain alkenyl-modified silane chitosan; The mass ratio of allyl glycidyl ether, chloroplatinic acid, and 1,1,3,3-tetramethyldisiloxane in (1) is 1:0.01-0.03:1.1-1.2; The reaction time in (2) is 6-8h; The ultrasonic oscillation time in (3) is 30-40 minutes; The reaction temperature in (4) is 85-110°C.

2. A method for preparing a polycarboxylate water-reducing agent containing nanomaterials according to claim 1, characterized in that: The preparation method of the polycarboxylate water-reducing agent containing nanomaterials is as follows: S1. Dissolve isopentanol polyoxyethylene ether in deionized water and stir to obtain solution A; S2. Methyl acrylate and diethylene glycol monoacrylate were dissolved in deionized water and stirred to obtain a solution B; S3. The mercaptoethanol reducing agent, thioglycolic acid chain transfer agent and sodium persulfate initiator were dissolved in deionized water and stirred to obtain solutions C, D, and E, respectively; S4. Add solution A, alkenyl-modified silane chitosan, water, ammonium chloride, and ferrous sulfate to a reactor, and add sodium persulfate initiator solution E, mercaptoethanol reducing agent solution C, and thioglycolic acid chain transfer agent solution D under stirring to initiate a polymerization reaction, and then add solution B dropwise thereto; after the dropwise addition is completed, react at 40-60°C for 2-6 hours, cool the product to room temperature, and then adjust the pH value to neutral with alkaline solution to obtain a polycarboxylic acid water reducer containing nanomaterials.

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