CN114316289A

CN114316289A - Seed crystal type polycarboxylate superplasticizer for prefabricated parts and preparation method thereof

Info

Publication number: CN114316289A
Application number: CN202111615964.3A
Authority: CN
Inventors: 朱少宏; 林艳梅; 蒋卓君; 官梦芹; 林晓琛
Original assignee: Kezhijie New Material Group Co Ltd
Current assignee: Kezhijie New Material Group Co Ltd
Priority date: 2021-12-27
Filing date: 2021-12-27
Publication date: 2022-04-12

Abstract

The invention relates to the technical field of building chemical materials, in particular to a seed crystal type polycarboxylate water reducer for prefabricated parts and a preparation method thereof. And simultaneously, more nucleation sites are provided through the sulfonic acid groups and the siloxane groups with the early strength function and the nano C-S-H crystal nucleus, the nucleation potential barrier is reduced, the hydration of mineral components in the cement is further promoted, the ettringite can be generated more quickly, the bleeding of fresh concrete is inhibited, the setting time is shortened, the early strength effect of the concrete is further enhanced, and the concrete early strength agent is particularly suitable for the precast member concrete with the early strength requirement.

Description

Seed crystal type polycarboxylate superplasticizer for prefabricated parts and preparation method thereof

Technical Field

The invention relates to the technical field of construction chemical materials, in particular to a seed crystal type polycarboxylate superplasticizer for prefabricated parts and a preparation method thereof.

Background

With the rapid development of the modern generation of China, the construction strength and scale of infrastructures, industries and civil buildings are continuously increased, and the concrete prefabricated part is changed into the demand and development direction of modern engineering. The traditional method for improving the early strength of concrete mainly comprises the steps of optimizing the mixing proportion, reducing the water-cement ratio, improving the cement mixing amount, adding an early strength agent and the like.

The types of the common early strength agents mainly comprise chloride salts, such as sodium chloride and calcium chloride; sulfates, such as sodium sulfate and sodium thiosulfate: organic early strength agents, such as triethanolamine and calcium formate. The chloride inorganic salt early strength agent is most obvious only from the early strength effect, but chloride ions are the main factors causing the corrosion of reinforced concrete, seriously affect the durability of the reinforced concrete and severely limit the application of the reinforced concrete.

CN109650398A discloses a calcium silicate hydrate early strength agent and a preparation method thereof, wherein the publication date is 04/19/2019, and the preparation method of the calcium silicate hydrate early strength agent comprises the following preparation steps: 1) preparing calcium liquid; 2) preparing silicon liquid by taking silicate ester as a silicon source; 3) and (3) synthesizing hydrated calcium silicate. After the calcium silicate hydrate early strength agent prepared by the preparation method is doped into cement, the cement hydration can be promoted, the cement setting time can be obviously shortened, the early strength of the cement can be improved, and the calcium silicate hydrate early strength agent has important practical application value in the field of buildings. Meanwhile, the problem of utilization of industrial waste is solved, and the production cost of the calcium silicate hydrate can be further reduced. However, in this embodiment, the calcium silicate hydrate crystal nuclei as the nano-sized particles are likely to agglomerate due to their large specific surface area, and the crystal nucleus action tends to be significantly reduced with time when the size is increased.

Under the condition of ensuring the final performance of concrete, the technology for improving the early strength of concrete is more and more important, however, the existing admixtures all have the problems of unobvious early strength effect and poor adaptability to cement.

Disclosure of Invention

In order to solve the problems of unobvious early strength effect, unobvious early strength effect and poor adaptability to cement of the existing concrete water reducing agent in the background art, the embodiment of the invention provides a preparation method of a seed crystal type polycarboxylate water reducing agent for prefabricated parts, which comprises the following steps: at the temperature of 25-55 ℃, mixing a polycarboxylic acid dispersant and water according to the ratio of 4-6: adjusting the pH value of the solution to 11-12 in a synthesis device according to the proportion of 25-30; and then mixing the silicon liquid and the calcium liquid according to the ratio of 5-6: 4-5, dropwise adding the mixture into a synthesis device, stirring and reacting to obtain a seed crystal type polycarboxylate superplasticizer for the prefabricated part;

preferably, the dropping speed is 8-12 mL/min, and the stirring speed is 1000-1500 rpm;

the polycarboxylic acid dispersant is prepared from the following raw materials: polyether macromonomer with high molecular weight, sulfonic acid group functional monomer, siloxane group functional monomer, unsaturated carboxylic acid comonomer, initiator, reducing agent, neutralizer and water:

wherein the mass ratio of the high molecular weight polyether macromonomer, the sulfonic acid group functional monomer, the siloxane group functional monomer and the unsaturated carboxylic acid comonomer is as follows: 180-200: 12-15: 8-10: 20 to 28.

On the basis of the technical scheme, in a preferred embodiment, the polycarboxylic acid dispersant comprises the following raw materials in parts by weight:

high molecular weight polyether macromonomer: 180-200 parts of a solvent;

sulfonic acid group functional monomer: 12-15 parts;

siloxane group functional monomer: 8-10 parts;

unsaturated carboxylic acid comonomer: 20-28 parts of a solvent;

initiator: 0.8-1.4 parts;

reducing agent: 2.5-3.0 parts;

neutralizing agent: 20-25 parts;

water: 150-200 parts.

On the basis of the above technical solution, in a preferred embodiment, the preparation method of the polycarboxylic acid dispersant comprises:

step one, adding a polyether macromonomer with high molecular weight, a siloxane group functional monomer, a reducing agent and water into a container, adding into a reaction device after ultrasonic treatment, controlling the temperature to be 55-65 ℃, and stirring to form a monomer mixed solution;

step two, mixing a sulfonic acid group functional monomer, an initiator and water, and adding the mixture into a first dripping device;

step three, mixing unsaturated carboxylic acid comonomer and water and adding the mixture into a second dripping device;

respectively dripping the solution in the first dripping device and the solution in the second dripping device into a reaction device, and reacting at the constant temperature of 55-65 ℃ for a period of time;

and step five, cooling the reaction temperature to room temperature, adding a neutralizer solution into the reaction device, and adjusting the pH value of the mixed solution to 7-8 to obtain the polycarboxylic acid dispersant.

On the basis of the above technical solution, in a preferred embodiment, the calcium solution is prepared by the following steps: dissolving 100-120 parts of calcium source in 60-80 parts of water, and heating to 60 ℃ for dissolution;

the preparation steps of the silicon liquid are as follows: dissolving 80-110 parts of silicon source in 100-120 parts of water, and heating to 60 ℃ for dissolving;

the calcium-silicon ratio of the calcium liquid to the silicon liquid is 1.0-1.5: 1.

based on the above technical solution, in a preferred embodiment, the silicon source is at least one of tetraethyl orthosilicate, tetrabutyl orthosilicate, tetrapropyl orthosilicate, sodium metasilicate pentahydrate, or sodium metasilicate nonahydrate, and the calcium source is at least one of calcium nitrate, calcium acetate, calcium nitrite, calcium gluconate, calcium hydrogen phosphate, or calcium dihydrogen phosphate.

On the basis of the technical scheme, in a preferred embodiment, the high molecular weight polyether macromonomer is one of isopentene polyoxyethylene ether with molecular weights of 4000, 5000 and 6000. The pentenyl polyoxyethylene ether adopted in the optimized scheme has the enhancement effect on the polymerization degree, the side chain density and the conversion rate of the prepared PCE, so that the improvement effect on the early strength performance is larger, and the cement hydration effect is more obvious.

On the basis of the technical scheme, in a preferred embodiment, the sulfonic acid group functional monomer is a solution formed by mixing one or more of 2-acrylamide-2-methylpropanesulfonic acid, sodium allylsulfonate or sodium vinylsulfonate.

On the basis of the technical scheme, in a preferred embodiment, the siloxane group functional monomer is a solution formed by mixing one or more of vinyl triacetoxysilane, gamma-aminopropyltriethoxysilane, vinyl tri (2-methoxyethoxy) silane, 3-methacryloxypropyl triisopropoxysilane and allyl triethoxysilane.

On the basis of the above technical solution, in a preferred embodiment, the unsaturated carboxylic acid comonomer is a mixed solution of one or more of acrylic acid, methacrylic acid, hydroxypropyl acrylate, maleic anhydride or itaconic anhydride;

the initiator is a solution formed by mixing one or more of ammonium persulfate, sodium persulfate, tert-butyl peroxypivalate or dicyclohexyl peroxydicarbonate; the reducing agent is a solution formed by mixing one or more of 2-hydroxy-2-sulfinic acid sodium acetate, sodium bisulfite, ascorbic acid or sodium hypophosphite; the neutralizer is a solution formed by mixing one or more of sodium hydroxide, calcium hydroxide, sodium methoxide, ammonia water or ethanolamine.

The invention also provides the seed crystal type polycarboxylate superplasticizer for the prefabricated part, which is prepared by the preparation method of the seed crystal type polycarboxylate superplasticizer for the prefabricated part.

According to the seed crystal type polycarboxylate water reducer for the prefabricated part, the sulfonic acid group and the siloxane group in a specific ratio, and the reasonable calcium-silicon ratio and the reasonable pH value are introduced into the structure of the polycarboxylate water reducer, so that the water reducer has a better early strength characteristic. And the polycarboxylic acid dispersing agent is directly used as the dispersing liquid, so that the long side chain steric hindrance effect of the polycarboxylic acid water reducing agent (PCE for short) molecules can be utilized, the polycarboxylic acid water reducing agent has a strong particle dispersing effect, the released water molecules are contacted with cement particles, and the normal hydration of the cement is ensured. Meanwhile, more nucleation sites can be provided through sulfonic acid groups and siloxane groups with early strength function and nano calcium silicate hydrate (C-S-H for short) crystal nuclei, the nucleation potential barrier is reduced, the hydration of mineral components in the cement is further promoted, the ettringite can be generated more quickly, the bleeding of fresh concrete is inhibited, the setting time is shortened, the early strength effect of the concrete is further enhanced, and the concrete early strength agent is particularly suitable for precast member concrete with early strength requirement.

Preferably, the calcium silicate hydrate seed crystal, namely C-S-H, prepared by the method has the characteristics of small particle size and high dispersibility, has a remarkable nucleating effect, can also obviously shorten the induction period of cement hydration, and enables the exothermic peak to be advanced, and simultaneously C-S-H also improves the exothermic rate during induction, the total exothermic quantity before the acceleration period begins, and the total exothermic quantity during the acceleration period.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The present invention provides the following examples:

example 1

A seed crystal type early-strength polycarboxylate superplasticizer for prefabricated parts comprises the following preparation steps:

at 45 ℃, 55 parts of polycarboxylic acid dispersant and 270 parts of water are put into a water bath synthesis device, the pH value of the solution is adjusted to be 11.5, the stirring speed is controlled to be 1200rpm, 100 parts of silicon solution and 83 parts of calcium solution which are prepared in advance are respectively dripped into the reaction device, and the dripping speed is controlled to be 10mL/mi n. Then, maintaining the reaction temperature, and continuously stirring at high speed for 8 hours to obtain the crystal-type early-strength polycarboxylate superplasticizer.

Wherein, the preparation steps of the calcium liquid are as follows: dissolving 105 parts of calcium nitrate in 65 parts of water, and heating to 60 ℃ for dissolution; the preparation steps of the silicon liquid are as follows: 85 parts of sodium metasilicate nonahydrate are dissolved in 110 parts of water, and the solution is heated to 60 ℃ for dissolution. And the ratio of calcium to silicon in the calcium liquid and the silicon liquid is 1.2: 1.

the polycarboxylic acid dispersant comprises the following preparation steps:

1) adding 180 parts of 6000 macromolecular weight isopentenyl polyoxyethylene ether macromonomer, 10 parts of vinyl triacetoxysilane functional monomer, 2.5 parts of sodium hypophosphite and 150 parts of water into a three-neck flask, performing ultrasonic treatment, adding into a reaction device, controlling the water bath temperature at 65 ℃, and stirring to form a monomer mixed solution;

2) mixing 12 parts of 2-acrylamide-2-methylpropanesulfonic acid functional monomer, 1.0 part of ammonium persulfate and 20 parts of water, and adding the mixture into a first dripping device;

3) mixing 24 parts of acrylic acid and 10 parts of water and adding the mixture to a second dripping device;

4) respectively dripping the solution in the first dripping device and the solution in the second dripping device into a reaction device, and reacting for 1h at the constant temperature of 65 ℃;

5) and cooling the reaction temperature to room temperature, adding 20 parts of calcium hydroxide solution into the reaction device, and adjusting the pH value of the mixed solution to 7 to obtain the polycarboxylic acid water reducing agent serving as the dispersing agent.

Example 2

at 40 ℃, 50 parts of polycarboxylic acid dispersant and 290 parts of water are placed in a water bath synthesis device, the pH value of the solution is adjusted to be 11.8, the stirring speed is controlled to be 1500rpm, 90 parts of silicon solution and 90 parts of calcium solution which are prepared in advance are respectively dripped into the reaction device, and the dripping speed is controlled to be 10 mL/min. Then, maintaining the reaction temperature, and continuously stirring at high speed for 8 hours to obtain a seed crystal type early-strength polycarboxylate superplasticizer for the prefabricated part;

wherein, the preparation steps of the calcium liquid are as follows: dissolving 105 parts of monocalcium phosphate in 65 parts of water, and heating to 60 ℃ for dissolution; the preparation steps of the silicon liquid are as follows: 85 parts of tetraethyl orthosilicate is dissolved in 110 parts of water and heated to 60 ℃ to be dissolved. Wherein the calcium-silicon ratio in the calcium liquid and the silicon liquid is 1: 1.

the polycarboxylic acid dispersant comprises the following preparation steps:

1) adding 190 parts of 5000 macromolecular weight isopentenyl polyoxyethylene ether macromonomer, 8 parts of gamma-aminopropyl triethoxysilane functional monomer, 2.8 parts of sodium hypophosphite and 150 parts of water into a three-neck flask, performing ultrasonic treatment, adding into a reaction device, controlling the temperature of a water bath at 65 ℃, and stirring to form a monomer mixed solution;

2) mixing 15 parts of sodium allylsulfonate functional monomer, 1.2 parts of sodium persulfate and 20 parts of water, and adding the mixture into a first dripping device;

3) 26 parts of methacrylic acid and 10 parts of water are mixed and then added to a second dropping device;

Example 3

at 50 ℃, 58 parts of polycarboxylic acid dispersant and 250 parts of water are placed in a water bath synthesis device, the pH value of the solution is adjusted to be 11.1, the stirring speed is controlled to be 1000rpm, 120 parts of silicon solution and 80 parts of calcium solution which are prepared in advance are respectively dripped into the reaction device, and the dripping speed is controlled to be 10 mL/min. Then, maintaining the reaction temperature, and continuously stirring at high speed for 8 hours to obtain a seed crystal type early-strength polycarboxylate superplasticizer for the prefabricated part;

wherein, the preparation steps of the calcium liquid are as follows: dissolving 105 parts of monocalcium phosphate in 65 parts of water, and heating to 60 ℃ for dissolution; the preparation steps of the silicon liquid are as follows: 85 parts of sodium metasilicate pentahydrate are dissolved in 110 parts of water, and the solution is heated to 60 ℃ for dissolution. Wherein the calcium-silicon ratio in the calcium liquid and the silicon liquid is 1.5: 1.

the polycarboxylic acid dispersant comprises the following preparation steps:

1) adding 200 parts of 4000 high molecular weight isopentenyl polyoxyethylene ether macromonomer, 9 parts of 3-methacryloxypropyl triisopropoxysilane functional monomer, 3.0 parts of sodium bisulfite and 150 parts of water into a three-neck flask, performing ultrasonic treatment, adding into a reaction device, controlling the temperature of a water bath at 65 ℃, and stirring to form a monomer mixed solution;

2) mixing 12 parts of sodium vinylsulfonate functional monomer, 1.4 parts of tert-butyl peroxypivalate and 20 parts of water, and adding the mixture into a first dripping device;

3) mixing 28 parts of hydroxypropyl acrylate and 10 parts of water, and adding the mixture into a second dripping device;

The invention also provides the following comparative examples:

comparative example 1

Comparative example 1 differs from example 1 in that: replacing sulfonic acid group functional monomers into water in the same proportion; all others were kept consistent.

Comparative example 2

Comparative example 1 differs from example 1 in that: replacing the siloxane group functional monomer into water in the same proportion; all others were kept consistent.

Comparative example 3

Comparative example 1 differs from example 1 in that: replacing the isopentenyl polyoxyethylene ether macromonomer with high molecular weight into isopentenyl polyoxyethylene ether macromonomer with low molecular weight (molecular weight of 2400) in the same proportion; all others were kept consistent.

The above examples and comparative examples were tested by the following methods: the above examples and comparative examples were subjected to a cement paste fluidity test according to the standard of GB 8077 "test method for homogeneity of concrete admixture", wherein the blending amount of the high-dispersing early-strength type polycarboxylic acid water reducing agent was 0.2% (folding and fixing blending amount), and the test results are shown in Table 1:

TABLE 1 Cement paste test

Sample (I)	Cement/g	Water/g	Water reducing agent mixing amount/%	Neat paste fluidity/mm
					Example 1	300	87	0.2	206
Example 2	300	87	0.2	201
					Example 3	300	87	0.2	198
Comparative example 1	300	87	0.2	186
					Comparative example 2	300	87	0.2	168
Comparative example 3	300	87	0.2	182

Experiments prove that the fluidity of the embodiment is superior to that of a comparative example, wherein the initial fluidity of the comparative example 2 is the worst, which shows that the dispersion performance is the worst, and the comparative examples 1-3 show that under the interaction of a sulfonic acid group functional monomer, a siloxane group functional monomer and a large molecular weight isopentenyl polyoxyethylene ether macromonomer, the adsorption capacity of cement particles can be improved, the formation of a neat and regular microstructure of cement hydration products in cement stone is promoted, and the adsorption of the cement hydration products on the cement particles is more uniform and dispersed.

According to the GB 8076-:

table 2 concrete mix proportion units: kg/m³

Cement	Sand	Crushing stone	Water (W)
				360	830	1000	175

TABLE 3 concrete workability test

The experimental results show that the initial extension of the concrete of the examples is superior to that of the comparative examples. Wherein, the flow dispersion performance and the early compressive strength performance of the comparative example 2 (no siloxane group functional monomer) are the worst, and the early compressive strength of the comparative example 1 (no sulfonic acid group functional monomer) and the comparative example 3 (low molecular weight prenylpolyoxyethylene ether macromonomer) are lower than those of the examples, so that the concrete dispersion performance can be improved and the early hydration of the concrete can be promoted only under the mutual promotion action of the sulfonic acid group functional monomer, the siloxane group functional monomer and the prenylpolyoxyethylene ether macromonomer with high molecular weight, thereby improving the 1d compressive strength and the 3d compressive strength performance of the concrete, and enabling the product to be better applied to precast member concrete.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. The preparation method of the seed crystal type polycarboxylate superplasticizer for the prefabricated part is characterized by comprising the following steps of: at the temperature of 25-55 ℃, mixing a polycarboxylic acid dispersant and water according to the ratio of 4-6: adjusting the pH value of the solution to 11-12 in a synthesis device according to the proportion of 25-30; and then mixing the silicon liquid and the calcium liquid according to the ratio of 5-6: 4-5, dropwise adding the mixture into a synthesis device, stirring and reacting to obtain a seed crystal type polycarboxylate superplasticizer for the prefabricated part;

2. The preparation method of the seed crystal type polycarboxylate superplasticizer for the prefabricated part according to claim 1, wherein the polycarboxylate dispersant comprises the following raw materials in parts by weight:

high molecular weight polyether macromonomer: 180-200 parts of a solvent;

sulfonic acid group functional monomer: 12-15 parts;

siloxane group functional monomer: 8-10 parts;

unsaturated carboxylic acid comonomer: 20-28 parts of a solvent;

initiator: 0.8-1.4 parts;

reducing agent: 2.5-3.0 parts;

neutralizing agent: 20-25 parts;

water: 150-200 parts.

3. The preparation method of the seed crystal type polycarboxylate superplasticizer for the prefabricated part according to claim 1, wherein the preparation method of the polycarboxylate dispersant is as follows:

4. The preparation method of the seed crystal type polycarboxylate superplasticizer for the prefabricated part according to claim 1, wherein the calcium solution is prepared by the following steps: dissolving 100-120 parts of calcium source in 60-80 parts of water, and heating to 60 ℃ for dissolution;

5. the preparation method of the seed crystal type polycarboxylate superplasticizer for prefabricated parts according to claim 4, characterized by comprising the following steps: the silicon source is at least one of tetraethyl orthosilicate, tetrabutyl orthosilicate, tetrapropyl orthosilicate, sodium metasilicate pentahydrate or sodium metasilicate nonahydrate, and the calcium source is at least one of calcium nitrate, calcium acetate, calcium nitrite, calcium gluconate, calcium hydrogen phosphate or calcium dihydrogen phosphate.

6. The preparation method of the seed crystal type polycarboxylate superplasticizer for prefabricated parts according to claim 4, characterized by comprising the following steps: the high molecular weight polyether macromonomer is one of isopentene polyoxyethylene ether with the molecular weight of 4000, 5000 and 6000.

7. The preparation method of the seed crystal type polycarboxylate superplasticizer for prefabricated parts according to claim 1, characterized by comprising the following steps: the sulfonic acid group functional monomer is a solution formed by mixing one or more of 2-acrylamide-2-methylpropanesulfonic acid, sodium allylsulfonate or sodium vinylsulfonate.

8. The preparation method of the seed crystal type polycarboxylate superplasticizer for prefabricated parts according to claim 1, characterized by comprising the following steps: the siloxane group functional monomer is a solution formed by mixing one or more of vinyl triacetoxysilane, gamma-aminopropyl triethoxysilane, vinyl tri (2-methoxyethoxy) silane, 3-methacryloxypropyl triisopropoxysilane or allyl triethoxysilane.

9. The preparation method of the seed crystal type polycarboxylate superplasticizer for prefabricated parts according to claim 1, characterized by comprising the following steps: the unsaturated carboxylic acid comonomer is a solution formed by mixing one or more of acrylic acid, methacrylic acid, hydroxypropyl acrylate, maleic anhydride or itaconic anhydride;

10. The seed crystal type polycarboxylate water reducer for the prefabricated parts, which is prepared by the preparation method of the seed crystal type polycarboxylate water reducer for the prefabricated parts according to any one of claims 1 to 9.