CN108821634B

CN108821634B - High-efficiency concrete water reducing agent and preparation method thereof

Info

Publication number: CN108821634B
Application number: CN201810942700.0A
Authority: CN
Inventors: 刘菊花; 路芸; 庞成荣
Original assignee: Yangquan Gaoxing Building Material Additive Co ltd
Current assignee: YANGQUAN GAOXING BUILDING MATERIAL ADDITIVE Co.,Ltd.
Priority date: 2018-08-17
Filing date: 2018-08-17
Publication date: 2020-10-23
Anticipated expiration: 2038-08-17
Also published as: CN108821634A

Abstract

The invention discloses a high-efficiency concrete water reducing agent and a preparation method thereof, belonging to the technical field of concrete additives. According to the invention, acrylic acid is taken as a raw material, polyethylene glycol monomethyl ether is added, a macromonomer is obtained through esterification, citric acid is added for modification, and the formation of calcium silicate hydrate gel is reduced, so that a higher water reducing rate is obtained; the invention takes the L-aspartic acid as the raw material to form carboxyl negative ions, so that the water reducing agent can still be well dispersed under the condition of hard water to perform the water reducing function; according to the invention, triethanolamine is introduced, so that the solubility of the surface of concrete particles is improved, and the water reducing efficiency is improved. The invention solves the problems of poor hard water resistance and low water reducing efficiency of the existing water reducing agent.

Description

High-efficiency concrete water reducing agent and preparation method thereof

Technical Field

The invention belongs to the technical field of concrete additives, and particularly relates to a high-efficiency concrete water reducing agent and a preparation method thereof.

Background

Concrete is a general term for engineering composite materials in which aggregate is cemented into a whole by a cementing material. The term concrete generally refers to cement as a cementing material and sand and stone as aggregate; the cement concrete, also called as common concrete, is obtained by mixing with water (which may contain additives and admixtures) according to a certain proportion and stirring, and is widely applied to civil engineering. When the cement mixture is operated, in order to save labor and effectively operate, early demolding shortens the construction period, the cement mixture is required to have high fluidity, meanwhile, the cement mixture can effectively inhibit the loss of slump, and the early hardening stage has sufficient early strength, so that a high-performance concrete water reducing agent is needed. The concrete water reducing agent is an additive which can reduce the mixing water consumption and improve the concrete under the condition of unchanged concrete workability and cement consumption, and can obstruct or destroy the flocculation structure of particles through surface activity, complexation, electrostatic repulsion force or three-dimensional repulsion force and the like, so that the workability and the strength of the concrete can be ensured while the cement consumption is saved. With the development of concrete science, the theory of polymer chemistry and material molecule design continuously makes new progress, and higher requirements are put forward on the concrete water reducing agent.

At present, water reducing agents can be mainly classified into four major categories according to their water reducing and strengthening abilities: firstly, the ordinary water reducing agent who uses lignin system as the owner, this type of water reducing agent mostly is the likepowder low bleed air nature retarder, has little bleed air nature, can improve the impervious freeze-thaw performance of concrete. However, the molecular structure of the water reducing agent mainly comprises aromatic rings, and the flexibility is poor. And the high-efficiency water reducing agent represented by a naphthalene water reducing agent is environmentally friendly and has high plasticity and high tolerance. However, the naphthalene water reducer is restricted by the molecular structure, and the problems of slump retaining performance and excessive mixing amount of concrete cannot be fundamentally improved. And thirdly, the polycarboxylic acid high-performance water reducing agent has high dispersibility, becomes a hotspot of current research, and develops rapidly. But it is not hard water resistant and affects the dosage. Fourthly, the aliphatic sulfonate water reducing agent has excellent water reducing characteristic, wherein the sulfonic group has strong hydrophilicity, can provide strong electric charge and can resist hard water. The aliphatic sulfonate water reducing agent is one of the main non-naphthalene water reducing agents developed in recent years, and is prepared by using acetone, formaldehyde, sodium sulfite, sodium pyrosulfite and the like as main raw materials, and the production process is simple and the production period is short. However, most of the monosulfonic acid groups and disulfonic acid groups are used as main materials, the water reducing performance of the monosulfonic acid groups and the disulfonic acid groups is poor, and meanwhile, the raw materials are polluted, have pungent odor and do not meet the requirements of green production. Therefore, a high-efficiency concrete water reducing agent with strong water reducing performance needs to be developed.

Disclosure of Invention

The technical problems to be solved by the invention are as follows: aiming at the problems of poor hard water resistance and low water reducing efficiency of the existing water reducing agent, the high-efficiency concrete water reducing agent and the preparation method thereof are provided.

In order to solve the technical problems, the invention adopts the following technical scheme:

a high-efficiency concrete water reducing agent comprises a water reducing active agent matrix, a hard water resisting chelating additive and an early strength additive;

the preparation method of the water-reducing active agent matrix comprises the following steps:

s1, taking acrylic acid according to a mass ratio of 2-5: 1-3, adding polyethylene glycol monomethyl ether, adding hydroquinone with the mass of 2-4% of that of acrylic acid to obtain a mixture, and mixing the mixture according to the mass ratio of 3-5: 8-10, adding toluene, introducing nitrogen for protection, adding p-toluenesulfonic acid with the mass of 1-3% of the mixture, stirring and mixing, and performing rotary evaporation to obtain a rotary evaporant;

s2, taking acrylic acid according to a mass ratio of 3-5: 7-9, adding N, N' -dicyclohexylcarbodiimide, stirring and mixing, adding citric acid with the mass 1-3 times that of acrylic acid, stirring and mixing at 40-50 ℃, adding p-dimethylaminopyridine with the mass 3-7% of the acrylic acid, heating to 60-70 ℃, stirring and mixing, carrying out reduced pressure distillation to obtain a reduced pressure distillate, and taking a rotary evaporant according to the mass ratio of 3-6: 4-7, adding the reduced pressure distillate and mixing to obtain the water-reducing active agent matrix.

The stirring and mixing conditions of the rotary evaporant obtained in the step S1 are as follows: heating to 110-120 ℃, stirring and mixing for 4-6 h, and performing rotary evaporation to obtain the product.

The preparation method of the anti-hard water chelating additive comprises the following steps:

(1) taking L-aspartic acid according to a mass ratio of 10-15: 3-5: 4-7, adding hydrochloric acid and phosphoric acid to obtain a mixture a, and mixing the mixture a with the mass ratio of 3-7: 10-15, adding deionized water, stirring and mixing, preserving heat, cooling to room temperature, freeze-drying, grinding, crushing, sieving with a 100-mesh sieve, collecting sieved particles, and washing with deionized water for 3-6 times to obtain a washed object;

(2) taking sodium hydroxide according to a mass ratio of 2-5: 7-10, adding deionized water, adding taurine with the mass 1-3 times that of sodium hydroxide, stirring and mixing to obtain a stirring mixture, and taking the washing materials according to the mass ratio of 1-5: 8-10, adding deionized water, heating to 35-45 ℃, adding a stirring mixture with the mass of 30-50% of the detergent, adjusting the pH to 7-7.2, and stirring and mixing to obtain the anti-hard water chelating additive.

The heat preservation conditions in the step (1) are as follows: heating to 150-160 ℃ and preserving the heat for 2-5 h.

The early strength additive is: taking triethanolamine according to a mass ratio of 2-4: and 3-6, adding sodium sulfate and mixing to obtain the early strength additive.

A preparation method of a high-efficiency concrete water reducing agent comprises the following steps:

A. taking 6-9 parts of a water-reducing active agent matrix, 4-7 parts of acrylic acid, 2-5 parts of sodium methallyl sulfonate and 80-90 parts of water by mass to obtain a matrix, heating to 50-60 ℃, dropwise adding ammonium persulfate accounting for 1-3% of the matrix mass, controlling the dropwise adding time to be 40-50 min, stirring and mixing, adjusting the pH to 6-7, and cooling to room temperature to obtain a cooling material;

B. according to the mass parts, 20-30 parts of a cooling material, 3-8 parts of a hard water-resistant chelating additive, 0.03-0.05 part of an early strength additive and 8-15 parts of montmorillonite are mixed, dried, crushed and sieved by a 200-mesh sieve, and sieved particles a are collected to obtain the high-efficiency concrete water reducer.

The stirring and mixing conditions in the step A are as follows: heating to 60-70 ℃, stirring and mixing for 3-5 h.

Compared with other methods, the method has the beneficial technical effects that:

(1) the invention takes acrylic acid as raw material, adds polyethylene glycol monomethyl ether, obtains macromonomer through esterification reaction, simultaneously introduces acrylic acid as raw material, adds N, N' -dicyclohexyl carbodiimide, carries out amidation reaction on dimethylaminopyridine, then adds citric acid for modification, obtains active main components of water reducing agent, compounds the rest macromonomer to form a water reducing active agent matrix, adds acrylic acid, sodium methyl propylene sulfonate and the like for initiating polymerization in later period, grafts the water reducing active agent matrix on the water reducing agent of polycarboxylic acid, obtains high-efficiency water reducing active agent, wherein a large amount of polar groups such as hydroxyl, carboxyl and the like have stronger hydroscopicity, the water reducing active agent is adsorbed on the surface of cement particles, the hydrophily can form a layer of solvation water film on the surface of the cement particles, and can destroy the flocculation structure of the cement particles, the partial mixing water wrapped in the cement grains is released, so that the cement grains are prevented from directly contacting, the cement grains are fully dispersed, the wettability of the surfaces of the water grains is improved, the flowability of the concrete is increased, the workability is good, and simultaneously the-COO in the matrix of the water reducing active agent is reduced^-The calcium hydroxide complex can form a complex with calcium ions in a cement hydration product, so that the crystallization of calcium hydroxide is delayed, the formation of hydrated calcium silicate gel is reduced, the dispersion and maintenance effects are achieved, the slump loss of concrete is reduced, the setting time is prolonged, carboxyl is further introduced into a molecular side chain of the water reducing agent by utilizing the modification of citric acid, the steric hindrance effect of the water reducing agent is improved, and the higher water reducing rate is obtained;

(2) the invention takes L-aspartic acid as a raw material, hydrochloric acid and phosphoric acid are added to form polyaspartic acid, taurine is added to modify the polyaspartic acid, and the anti-hard water chelating additive is obtained, is polyamino acid with carboxyl side chains, has chelating and dispersing effects, contains a large number of active groups such as peptide bonds, carboxyl and the like, has good hydrophilicity and water solubility, can be easily ionized in water solution by-COOH on the side chains to form carboxyl negative ions, can carry out complex reaction with calcium bicarbonate, magnesium bicarbonate and the like in hard water to form soluble ions, so that the water reducing agent can still be well dispersed under the condition of hard water to have the water reducing effect;

(3) the invention introduces triethanolamine, N atom in the molecular structure of the triethanolamine has lone pair electrons and can react with calcium, iron ions and the like to generate a complex, the solubility of the surface of concrete particles is improved, the hydration of tricalcium aluminate and the generation of ettringite are promoted, the triethanolamine is compounded with sodium sulfate, sulfate radical ions can react with calcium hydroxide generated when cement is hydrated to generate calcium sulfate with extremely fine particle size, and therefore, the calcium sulfate can react with tricalcium aluminate to generate ettringite more easily, the hydration speed is accelerated, the early strength of cement hardening is improved, the compactness of concrete is improved, simultaneously, the montmorillonite is added, the water reducing agent adsorbs the montmorillonite with negative charges among layers through ion exchange and ion exchange, meanwhile, carbon-hydrogen bonds contained in the water reducing agent can also generate Van der Waals attraction with non-polar mass points among the montmorillonite layers to be adsorbed, the density of negative charges among the montmorillonite layers is increased due to the adsorption of negative ions, the repulsion force between the layers is correspondingly increased, so that the interlayer distance is enlarged, the water reducing agent can be uniformly dispersed in the cement, and the water reducing efficiency is improved.

Detailed Description

Water-reduced active agent matrix: s1, taking acrylic acid according to a mass ratio of 2-5: 1-3, adding polyethylene glycol monomethyl ether, adding hydroquinone with the mass of 2-4% of that of acrylic acid to obtain a mixture, and mixing the mixture according to the mass ratio of 3-5: 8-10, adding toluene, introducing nitrogen for protection, adding p-toluenesulfonic acid with the mass of 1-3% of the mixture, heating to 110-120 ℃, stirring and mixing for 4-6 hours, and performing rotary evaporation to obtain a rotary evaporant;

s2, taking acrylic acid according to a mass ratio of 3-5: adding N, N' -dicyclohexylcarbodiimide (N-dicyclohexylcarbodiimide) 7-9, stirring and mixing for 20-30 min, adding citric acid 1-3 times of the mass of acrylic acid, stirring and mixing for 30-50 min at 40-50 ℃, adding p-dimethylaminopyridine 3-7% of the mass of acrylic acid, heating to 60-70 ℃, stirring and mixing for 10-12 h, carrying out reduced pressure distillation to obtain a reduced pressure distillate, and taking a rotary evaporant according to the mass ratio of 3-6: 4-7, adding the reduced pressure distillate and mixing to obtain the water-reducing active agent matrix.

Hard water sequestering additives: (1) taking L-aspartic acid according to a mass ratio of 10-15: 3-5: 4-7, adding hydrochloric acid with the mass fraction of 36% and phosphoric acid with the mass fraction of 85% to obtain a mixture a, and taking the mixture a according to the mass ratio of 3-7: 10-15 adding deionized water, stirring and mixing for 30-50 min, heating to 150-160 ℃, preserving heat for 2-5 h, cooling to room temperature, freeze-drying, grinding, crushing, sieving with a 100-mesh sieve, collecting sieved particles, and washing with deionized water for 3-6 times to obtain a washed object;

(2) taking sodium hydroxide according to a mass ratio of 2-5: 7-10, adding deionized water, adding taurine with the mass 1-3 times that of sodium hydroxide, stirring and mixing for 10-20 min to obtain a stirring mixture, and taking washings according to the mass ratio of 1-5: 8-10, adding deionized water, heating to 35-45 ℃, adding a stirring mixture with the mass of 30-50% of the detergent, adjusting the pH to 7-7.2, and stirring and mixing for 1-3 hours to obtain the anti-hard water chelating additive.

Early strength additive: taking triethanolamine according to a mass ratio of 2-4: and 3-6, adding sodium sulfate and mixing to obtain the early strength additive.

A. taking 6-9 parts of a water-reducing active agent matrix, 4-7 parts of acrylic acid, 2-5 parts of sodium methallyl sulfonate and 80-90 parts of water by mass to obtain a matrix, heating to 50-60 ℃, dropwise adding ammonium persulfate accounting for 1-3% of the matrix mass, controlling the dropwise adding time to be 40-50 min, heating to 60-70 ℃, stirring and mixing for 3-5 h, adjusting the pH to 6-7, and cooling to room temperature to obtain a cooling substance;

Water-reduced active agent matrix: s1, taking acrylic acid according to a mass ratio of 2: 1, adding polyethylene glycol monomethyl ether, adding hydroquinone with the mass of 2% of acrylic acid to obtain a mixture, and mixing the mixture according to the mass ratio of 3: 8, adding toluene, introducing nitrogen for protection, adding p-toluenesulfonic acid with the mass of 1% of the mixture, heating to 110 ℃, stirring and mixing for 4 hours, and performing rotary evaporation to obtain a rotary evaporant;

s2, taking acrylic acid according to a mass ratio of 3: 7, adding N, N' -dicyclohexylcarbodiimide, stirring and mixing for 20min, adding citric acid with the mass 1 time that of acrylic acid, stirring and mixing for 30min at 40 ℃, adding p-dimethylaminopyridine with the mass 3% of the acrylic acid, heating to 60 ℃, stirring and mixing for 10h, carrying out reduced pressure distillation to obtain a reduced pressure distillate, and taking a rotary evaporant according to the mass ratio of 3: 4 adding the reduced pressure distillate and mixing to obtain the water-reducing active agent matrix.

Hard water sequestering additives: (1) taking the L-aspartic acid according to the mass ratio of 10: 3: 4, adding hydrochloric acid with the mass fraction of 36% and phosphoric acid with the mass fraction of 85% to obtain a mixture a, and taking the mixture a according to the mass ratio of 3: 10 adding deionized water, stirring and mixing for 30min, heating to 150 ℃, keeping the temperature for 2h, cooling to room temperature, freeze-drying, grinding, sieving with a 100-mesh sieve, collecting sieved particles, and washing with deionized water for 3 times to obtain a washed object;

(2) taking sodium hydroxide according to a mass ratio of 2: 7, adding deionized water, adding taurine with the mass 1 time that of the sodium hydroxide, stirring and mixing for 10min to obtain a stirring mixture, and taking washings according to the mass ratio of 1: and 8, adding deionized water, heating to 35 ℃, adding a stirring mixture with the mass of 30% of the washing substance, adjusting the pH to 7, and stirring and mixing for 1h to obtain the anti-hard water chelating additive.

Early strength additive: taking triethanolamine according to a mass ratio of 2: 3, adding sodium sulfate and mixing to obtain the early strength additive.

A. taking 6 parts of a water-reducing active agent matrix, 4 parts of acrylic acid, 2 parts of sodium methallyl sulfonate and 80 parts of water according to the mass parts to obtain a matrix, heating to 50 ℃, dropwise adding ammonium persulfate accounting for 1% of the mass of the matrix, controlling the dropwise adding time to be 40min, heating to 60 ℃, stirring and mixing for 3h, adjusting the pH value to 6, and cooling to room temperature to obtain a cooling material;

B. and (2) mixing 20 parts of a cooling material, 3 parts of a hard water-resistant chelating additive, 0.03 part of an early strength additive and 8 parts of montmorillonite, drying, crushing, sieving with a 200-mesh sieve, and collecting sieved particles a to obtain the high-efficiency concrete water reducer.

Water-reduced active agent matrix: s1, taking acrylic acid according to a mass ratio of 4: 2, adding polyethylene glycol monomethyl ether, adding hydroquinone with the mass of 3% of acrylic acid to obtain a mixture, and mixing the mixture according to a mass ratio of 4: 9, adding toluene, introducing nitrogen for protection, adding p-toluenesulfonic acid with the mass of 2% of the mixture, heating to 115 ℃, stirring and mixing for 5 hours, and performing rotary evaporation to obtain a rotary evaporant;

s2, taking acrylic acid according to a mass ratio of 4: 8, adding N, N' -dicyclohexylcarbodiimide, stirring and mixing for 25min, adding citric acid 2 times the mass of acrylic acid, stirring and mixing for 40min at 45 ℃, adding p-dimethylaminopyridine 5% of the mass of acrylic acid, heating to 65 ℃, stirring and mixing for 11h, carrying out reduced pressure distillation to obtain a reduced pressure distillate, and taking a rotary evaporant according to the mass ratio of 5: 5 adding the reduced pressure distillate and mixing to obtain the water-reducing active agent matrix.

Hard water sequestering additives:

(1) taking L-aspartic acid according to a mass ratio of 13: 4: 5, adding hydrochloric acid with the mass fraction of 36% and phosphoric acid with the mass fraction of 85% to obtain a mixture a, and taking the mixture a according to the mass ratio of 5: 13 adding deionized water, stirring and mixing for 40min, heating to 155 ℃, keeping the temperature for 4h, cooling to room temperature, freeze-drying, grinding, sieving with a 100-mesh sieve, collecting the sieved particles, and washing with deionized water for 5 times to obtain a washed object;

(2) taking sodium hydroxide according to a mass ratio of 4: 8, adding deionized water, adding taurine 2 times of the mass of the sodium hydroxide, stirring and mixing for 15min to obtain a stirring mixture, and taking washings according to the mass ratio of 4: 9 adding deionized water, heating to 40 ℃, adding a stirring mixture with the mass of 40% of the detergent, adjusting the pH to 7.1, and stirring and mixing for 2 hours to obtain the anti-hard water chelating additive.

Early strength additive: taking triethanolamine according to a mass ratio of 3: 5, adding sodium sulfate and mixing to obtain the early strength additive.

A. according to the mass parts, taking 8 parts of a water-reducing active agent matrix, 5 parts of acrylic acid, 3 parts of sodium methallyl sulfonate and 85 parts of water to obtain a matrix, heating to 55 ℃, dropwise adding ammonium persulfate accounting for 2% of the mass of the matrix, controlling the dropwise adding time to be 45min, heating to 65 ℃, stirring and mixing for 4h, adjusting the pH to 6.5, and cooling to room temperature to obtain a cooled substance;

B. according to the mass parts, 25 parts of a cooling material, 6 parts of a hard water resistant chelating additive, 0.04 part of an early strength additive and 13 parts of montmorillonite are mixed, dried, crushed and sieved by a 200-mesh sieve, and sieved particles a are collected to obtain the high-efficiency concrete water reducer.

Water-reduced active agent matrix: s1, taking acrylic acid according to a mass ratio of 5: 3, adding polyethylene glycol monomethyl ether, adding hydroquinone with the mass of 4% of that of the acrylic acid to obtain a mixture, and mixing the mixture according to a mass ratio of 5: 10, adding toluene, introducing nitrogen for protection, adding p-toluenesulfonic acid with the mass of 3% of that of the mixture, heating to 120 ℃, stirring and mixing for 6 hours, and performing rotary evaporation to obtain a rotary evaporant;

s2, taking acrylic acid according to a mass ratio of 5: 9 adding N, N' -dicyclohexylcarbodiimide, stirring and mixing for 30min, adding citric acid with the mass 3 times of that of acrylic acid, stirring and mixing for 50min at 50 ℃, adding p-dimethylaminopyridine with the mass 7% of that of the acrylic acid, heating to 70 ℃, stirring and mixing for 12h, carrying out reduced pressure distillation to obtain a reduced pressure distillate, and taking a rotary evaporant according to the mass ratio of 6: 7 adding the reduced pressure distillate and mixing to obtain the water-reducing active agent matrix.

Hard water sequestering additives:

(1) taking L-aspartic acid according to a mass ratio of 15: 5: 7, adding hydrochloric acid with the mass fraction of 36% and phosphoric acid with the mass fraction of 85% to obtain a mixture a, and taking the mixture a according to the mass ratio of 7: 15 adding deionized water, stirring and mixing for 50min, heating to 160 ℃, keeping the temperature for 5h, cooling to room temperature, freeze-drying, grinding, sieving with a 100-mesh sieve, collecting the sieved particles, and washing with deionized water for 6 times to obtain a washed object;

(2) taking sodium hydroxide according to a mass ratio of 5: 10, adding deionized water, adding taurine with the mass 3 times that of sodium hydroxide, stirring and mixing for 20min to obtain a stirring mixture, and taking washings according to the mass ratio of 5: 10, adding deionized water, heating to 45 ℃, adding a stirring mixture with 50% of the mass of the washing substance, adjusting the pH to 7.2, and stirring and mixing for 1-3 hours to obtain the anti-hard water chelating additive.

Early strength additive: taking triethanolamine according to a mass ratio of 4: 6, adding sodium sulfate and mixing to obtain the early strength additive.

A. taking 9 parts of a water-reducing active agent matrix, 7 parts of acrylic acid, 5 parts of sodium methallyl sulfonate and 90 parts of water according to the mass parts to obtain a matrix, heating to 60 ℃, dropwise adding ammonium persulfate accounting for 3% of the mass of the matrix, controlling the dropwise adding time to be 50min, heating to 70 ℃, stirring and mixing for 5h, adjusting the pH value to 7, and cooling to room temperature to obtain a cooled substance;

B. and (2) mixing 30 parts of a cooling material, 8 parts of a hard water-resistant chelating additive, 0.05 part of an early strength additive and 15 parts of montmorillonite, drying, crushing, sieving with a 200-mesh sieve, and collecting sieved particles a to obtain the high-efficiency concrete water reducer.

Comparative example 1: essentially the same procedure as in example 1, except that the reduced water active agent matrix is absent.

Comparative example 2: essentially the same procedure as in example 1, except that the hard water sequestering additive was absent.

Comparative example 3: essentially the same procedure as in example 1 was followed except that the early strength additive was absent.

Comparative example 4: a concrete water reducing agent produced by a certain company in Dazhou city.

The concrete water reducing agents obtained in the examples and the comparative examples are tested according to the GB/T50081-2002 standard, and the test results are shown in the following table 1:

table 1:

test items	Example 1	Example 2	Example 3	Comparative example 1	Comparative example 2	Comparative example 3	Comparative example 4
								Water loss (%)	33	31	30	27	29	29	14.5
Bleeding Rate (%)	18	20	19	19	21	22	41
								Gas content (%)	1.5	1.6	1.7	1.9	2.0	1.8	3.2

Sample 3g was weighed into a 200mL beaker, 97g water was added, heated to 60-65 ℃ and stirred with a glass rod for 5min before being allowed to cool to room temperature. Taking 25mL of supernatant liquid, pouring into a test tube, adding 25mL of artificial hard water, shaking uniformly, and placing in water with the temperature of 65 ℃ and the temperature of 2 ℃ for 1 h. The test tube was taken out after 1 hour, immediately subjected to appearance inspection, and then cooled to room temperature to perform hard water resistance test. The test results are shown in table 2:

table 2:

test items

Example 1

Example 2

Example 3

Comparative example 1

Comparative example 2

Comparative example 3

Comparative example 4

Whether there is any precipitate

Whether or not

Is slightly provided with

Whether or not

Is provided with

In conclusion, compared with the commercially available product, the high-efficiency concrete water reducing agent disclosed by the invention has a better effect and is worthy of great popularization.

Claims

1. The high-efficiency concrete water reducing agent is characterized by comprising a water reducing active agent matrix, a hard water resistance chelating additive and an early strength additive;

s1, taking acrylic acid according to a mass ratio of 2-5: 1-3, adding polyethylene glycol monomethyl ether, adding hydroquinone with the mass of 2-4% of that of acrylic acid to obtain a mixture, and mixing the mixture according to the mass ratio of 3-5: 8-10, adding toluene, introducing nitrogen for protection, adding p-toluenesulfonic acid with the mass of 1-3% of the mixture, heating to 110-120 ℃, stirring and mixing for 4-6 hours, and performing rotary evaporation to obtain a rotary evaporant;

s2, taking acrylic acid according to a mass ratio of 3-5: adding N, N' -dicyclohexylcarbodiimide (N-dicyclohexylcarbodiimide) 7-9, stirring and mixing for 20-30 min, adding citric acid 1-3 times of the mass of acrylic acid, stirring and mixing for 30-50 min at 40-50 ℃, adding p-dimethylaminopyridine 3-7% of the mass of acrylic acid, heating to 60-70 ℃, stirring and mixing for 10-12 h, carrying out reduced pressure distillation to obtain a reduced pressure distillate, and taking a rotary evaporant according to the mass ratio of 3-6: 4-7, adding the reduced pressure distillate and mixing to obtain a water-reducing active agent matrix;

(1) taking L-aspartic acid according to a mass ratio of 10-15: 3-5: 4-7, adding hydrochloric acid with the mass fraction of 36% and phosphoric acid with the mass fraction of 85% to obtain a mixture a, and taking the mixture a according to the mass ratio of 3-7: 10-15 adding deionized water, stirring and mixing for 30-50 min, heating to 150-160 ℃, preserving heat for 2-5 h, cooling to room temperature, freeze-drying, grinding, crushing, sieving with a 100-mesh sieve, collecting sieved particles, and washing with deionized water for 3-6 times to obtain a washed object;

(2) taking sodium hydroxide according to a mass ratio of 2-5: 7-10, adding deionized water, adding taurine with the mass 1-3 times that of sodium hydroxide, stirring and mixing for 10-20 min to obtain a stirring mixture, and taking washings according to the mass ratio of 1-5: 8-10, adding deionized water, heating to 35-45 ℃, adding a stirred mixture with the mass of 30-50% of the detergent, adjusting the pH to 7-7.2, and stirring and mixing for 1-3 hours to obtain the hard water-resistant chelating additive;

the early strength additive is: taking triethanolamine according to a mass ratio of 2-4: 3-6, adding sodium sulfate and mixing to obtain the early strength additive;