阅读说明：本技术 一种无碱液体速凝剂及其制备方法和应用 (Alkali-free liquid accelerator and preparation method and application thereof ) 是由 马雪英 侯博智 王宏维 于 2021-01-05 设计创作，主要内容包括：本发明公开了一种无碱液体速凝剂及其制备方法和应用,按质量份,所述无碱液体速凝剂的原料组分包括：醇铝12-18份；硝酸铝7-13份；硫酸铝25-35份；醇胺4-8份；含氟无机酸12-18份；组分A 10-20份；水6-12份；其中,所述组分A为二甲基亚砜和/或二甲基甲酰胺。本发明可使产品的低温稳定性大幅增加,能够在-20℃环境中长期储存。(The invention discloses an alkali-free liquid accelerator and a preparation method and application thereof, and the alkali-free liquid accelerator comprises the following raw material components in parts by mass: 12-18 parts of aluminum alkoxide; 7-13 parts of aluminum nitrate; 25-35 parts of aluminum sulfate; 4-8 parts of alcohol amine; 12-18 parts of fluorine-containing inorganic acid; 10-20 parts of a component A; 6-12 parts of water; wherein the component A is dimethyl sulfoxide and/or dimethylformamide. The invention can greatly increase the low-temperature stability of the product and can be stored for a long time in the environment of 20 ℃ below zero.)

1. The alkali-free liquid accelerator is characterized by comprising the following raw material components in parts by mass:

wherein the component A is dimethyl sulfoxide and/or dimethylformamide.

2. The alkali-free liquid accelerator according to claim 1, wherein the component a is 12 to 18 parts.

3. The alkali-free liquid accelerator according to claim 1 or 2, wherein the alcohol amine is one or more of diethanolamine, triethanolamine, diethanol monoisopropanolamine and triisopropanolamine, and/or the fluorine-containing inorganic acid is hydrofluoric acid and/or fluosilicic acid.

4. The alkali-free liquid accelerator according to any one of claims 1 to 3, wherein the aluminum sulfate is aluminum sulfate octadecahydrate, and/or the aluminum nitrate is technical-grade powdery aluminum nitrate.

5. The alkali-free liquid accelerator according to any one of claims 1 to 4, wherein the aluminum alkoxide is one or a combination of aluminum ethoxide, aluminum isopropoxide and aluminum tert-butoxide.

6. A method for preparing the alkali-free liquid accelerator as claimed in any one of claims 1 to 5, wherein the raw material components of the alkali-free liquid accelerator are metered and mixed to obtain the alkali-free liquid accelerator.

7. The method of claim 6, comprising the steps of:

metering the components and parts by mass of the alkali-free liquid accelerator; and sequentially adding the component A, aluminum alcohol, water, aluminum sulfate, alcohol amine, aluminum nitrate and fluorine-containing inorganic acid, and stirring to obtain the alkali-free liquid accelerator.

8. The method of claim 7, comprising the steps of:

(1) weighing the raw material components and the mixture ratio of the alkali-free liquid accelerator, and dividing the weighed aluminum sulfate into first aluminum sulfate and second aluminum sulfate;

(2) mixing the component A with aluminum alkoxide;

(3) adding water and then adding first aluminum sulfate;

(4) adding alcohol amine;

(5) adding aluminum nitrate and second aluminum sulfate;

(6) and adding a fluorine-containing inorganic acid to obtain the alkali-free liquid accelerator.

9. The process according to any one of claims 6 to 8, wherein the first aluminum sulfate is 65 to 85 mass% and the second aluminum sulfate is 15 to 35 mass%, based on the total weight of the aluminum sulfates; and/or the presence of a gas in the gas,

mixing the raw material components in a container, and keeping the temperature in the container to be 50-65 ℃ during the mixing process.

10. Use of the alkali-free liquid accelerator according to any one of claims 1 to 5 or the alkali-free liquid accelerator obtained by the production method according to any one of claims 6 to 9 in concrete.

Technical Field

The invention relates to an alkali-free liquid accelerator as well as a preparation method and application thereof, in particular to an alkali-free liquid accelerator for construction in a cold environment, and belongs to the technical field of concrete admixtures.

Background

At present, with the increase of the speed of domestic infrastructure, the concrete spraying technology is being widely popularized and applied in China. The sprayed concrete has many advantages compared with molded concrete because no plate making is needed in the construction process and a plurality of processes can be combined into one, and is widely applied to projects such as tunnels, mines, revetments, culverts and the like. The current concrete spraying construction technology is mainly divided into a dry spraying method and a wet spraying method. The dry-spraying method is currently being replaced by wet-sprayed concrete due to the defects of high rebound rate, severe construction environment, poor quality stability and the like.

The accelerator is an additive necessary for sprayed concrete, and the main action mechanism of the accelerator is to quickly hydrate and coagulate cement in mortar or concrete so as to achieve the effect of accelerating setting. The powdery accelerator is mainly applied to dry-spraying concrete, and the accelerator for the wet spraying method is almost all liquid accelerator. The liquid accelerator can be still subdivided into an alkali-free accelerator and an alkali accelerator according to the alkali content, wherein the alkali-free accelerator has good later strength, but the doping amount is generally larger and the cost is higher; the alkali accelerator has low mixing amount and high early strength, but the later strength of the alkali accelerator is usually lost more due to the reaction of alkali aggregates.

The breadth of our country is broad, the latitude span is extremely large, and the heat band composition is complex. If the conditions and special conditions of national infrastructure are comprehensively considered, the construction problem in cold seasons in high-latitude areas is also urgently considered. At present, in the northeast region of China, the annual construction time is less than 60% of the annual time, and how to solve the problem of construction in cold seasons becomes an important task for accelerating the infrastructure of high latitude regions in China. The existing liquid accelerator can be frozen and crystallized in the processes of low-temperature storage, transportation and construction; the liquid accelerator loses or even loses accelerating effect after being thawed.

Disclosure of Invention

The invention aims to solve the technical problems that the existing liquid accelerator has poor freezing resistance, can be frozen and crystallized during low-temperature storage, transportation and construction, and has poor accelerating effect after being thawed.

In order to solve the technical problem, the invention provides an alkali-free liquid accelerator which comprises the following raw material components in percentage by mass:

the alkali-free liquid accelerator comprises the following raw materials in parts by mass:

wherein the component A is dimethyl sulfoxide and/or dimethylformamide.

According to experiments, the inventor finds that the effect of adding dimethyl sulfoxide is better than that of dimethylformamide, and the component A of the invention is most preferably dimethyl sulfoxide. The amount of component A is preferably from 12 to 18 parts.

Preferably, the aluminum alkoxide is one or a combination of aluminum ethoxide, aluminum isopropoxide and aluminum tert-butoxide.

Preferably, the aluminum sulfate is aluminum sulfate octadecahydrate.

Preferably, the aluminum nitrate is technical grade powdered aluminum nitrate.

Preferably, the alcohol amine is one or a combination of more of diethanolamine, triethanolamine, diethanol monoisopropanolamine and triisopropanolamine.

Preferably, the fluorine-containing inorganic acid is hydrofluoric acid and/or fluorosilicic acid.

Preferably, the invention also provides a raw material of the alkali-free liquid accelerator, which consists of the raw material components.

The concentration of the fluosilicic acid is 25 to 35 percent (mass fraction); more preferably, the concentration of the fluosilicic acid is 30 to 32 percent (mass fraction).

The concentration of the hydrofluoric acid is 35-45% (mass fraction); more preferably, the concentration of hydrofluoric acid is 39 to 41% (mass fraction).

The invention also provides a preparation method of the alkali-free liquid accelerator, which comprises the steps of metering and mixing the raw material components of the alkali-free liquid accelerator to obtain the alkali-free liquid accelerator.

Preferably, the preparation method of the invention specifically comprises the following steps:

metering the components and parts by mass of the alkali-free liquid accelerator; and sequentially adding the component A, aluminum alcohol, water, aluminum sulfate, alcohol amine, aluminum nitrate and fluorine-containing inorganic acid, and stirring to obtain the alkali-free liquid accelerator.

Specifically, the preparation method comprises the following steps:

(1) weighing the raw material components and the mixture ratio of the alkali-free liquid accelerator, and dividing the weighed aluminum sulfate into first aluminum sulfate and second aluminum sulfate;

(2) mixing the component A with aluminum alkoxide;

(3) adding water and then adding first aluminum sulfate;

(4) adding alcohol amine;

(5) adding aluminum nitrate and second aluminum sulfate;

(6) and adding a fluorine-containing inorganic acid to obtain the alkali-free liquid accelerator.

Preferably, the first aluminum sulfate is 65 to 85 mass% and the second aluminum sulfate is 15 to 35 mass% based on the total weight of aluminum sulfate.

Preferably, the temperature in the reaction vessel is maintained between 50 and 65 ℃. The reaction vessel may be heated and incubated by a water bath. The raw material dissolution can be accelerated by slightly heating, the reaction rate is improved, and the preparation time is shortened.

Preferably, the aluminium sulphate in step (1) is split into two parts, one part being added in step (3) (aluminium sulphate is added after the addition of water is complete); the other part is added in the step (5) (added together with the aluminum nitrate or added after the aluminum nitrate is added). Since the solubility of aluminum sulfate is low, if all the required aluminum sulfate is added in step (3), the rate of addition of aluminum sulfate needs to be controlled very slowly. The aluminum sulfate is divided into two parts and is respectively added in the step (3) and the step (5), so that the adding speed of the aluminum sulfate can be better controlled, and the suspension system of the liquid accelerator is also formed. Generally, 60-85% (mass fraction) of the desired aluminum sulfate is added in step (3) and the remaining aluminum sulfate is added in step (5) in terms of mass percentage. Preferably, the rest of aluminum sulfate is added after the addition of aluminum nitrate in the step (5) is finished.

In order to prevent the raw material components of the accelerator from reacting too fast during the addition process, the addition speed of each component is generally controlled and preferably added while stirring. After one raw material component is added, stirring can be continued for about 20 minutes to ensure complete dissolution and reaction.

The invention also provides the application of the alkali-free liquid accelerator and the alkali-free liquid accelerator obtained by the preparation method in concrete.

Compared with the traditional alkali-free liquid accelerator, the invention adopts soluble aluminum salt or aluminum alkoxide, and the alkali-free liquid accelerator contains a large amount of complex aluminum ions, so that the low-temperature stability of the product is greatly improved; the component A can improve the solubility of aluminum alkoxide, can obviously reduce the freezing point of the whole product after being mutually dissolved with water, can be used as an anti-freezing component of the whole accelerator together with micromolecular alcohol (such as ethanol, isopropanol or tert-butyl alcohol) after the aluminum alkoxide is hydrolyzed, and simultaneously nitrate ions after the aluminum nitrate is hydrolyzed can also play a certain anti-freezing role. The product of the invention can be stored for a long time in the environment of minus 20 ℃, and can meet the construction requirement of the environment below minus 15 ℃ after being mixed with the concrete antifreezing agent for use.

Detailed Description

The present invention will be further described with reference to examples and comparative examples. Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.

Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.

Example 1

This example provides an alkali-free liquid accelerator, which is prepared as follows:

(1) 1kg of the alkali-free liquid accelerator is prepared, and the required raw material components are as follows:

(2) placing a 1000ml four-neck flask in a water bath kettle, and setting the temperature to be 50 ℃; weighing 150g of dimethyl sulfoxide, pouring the dimethyl sulfoxide into a four-neck flask, and starting stirring, wherein the stirring speed is set to 300 rpm; weighing 150g of aluminum isopropoxide, slowly pouring into a four-neck flask, and controlling pouring time for 20 min; stirring was then continued for 30 min.

(3) 90g of deionized water is weighed and added into a four-neck flask, and a water bath kettle is heated to 65 ℃. 240g of aluminum sulfate is weighed and slowly poured into a four-mouth flask, and the pouring time is controlled to be about 20 min. After all the materials are poured, the stirring is continued for 30min by maintaining the rotating speed of the stirrer at 300 rpm.

(4) 60g of triethanolamine is weighed and poured into a four-neck flask, and stirred for 20 min.

(5) 100g of aluminum nitrate is weighed and poured into a four-neck flask, 60g of aluminum sulfate is weighed and slowly poured into the four-neck flask, and the mixture is stirred for 20 min.

(6) 150g of fluosilicic acid with the concentration of 32 percent (mass fraction) is weighed and slowly dripped into a four-neck flask, and the dripping time is controlled for 10 min. And maintaining the rotating speed of the stirrer to be 300rpm, and stirring for 1.5h to obtain the anti-freezing alkali-free liquid accelerator.

Example 2

This example provides an alkali-free liquid quick-setting admixture, which is prepared in the same manner as in example 1, except that: the dosage of the dimethyl sulfoxide is increased from 150g to 180g, and other components, the dosage and the preparation method are not changed.

Example 3

This example provides an alkali-free liquid quick-setting admixture, which is prepared in the same manner as in example 1, except that: the dosage of the dimethyl sulfoxide is reduced from 150g to 120g, and other components, the dosage and the preparation method are not changed.

Example 4

This example provides an alkali-free liquid quick-setting admixture, which is prepared in the same manner as in example 1, except that: dimethyl sulfoxide is replaced by dimethyl formamide, and other components, the using amount and the preparation method are unchanged.

Example 5

This example provides an alkali-free liquid quick-setting admixture, which is prepared by the same method as in example 1 except that: 300g of aluminum sulfate was added in the whole in the step (3).

Comparative example 1

JW-18A type low-alkali accelerator produced by Shanxi Jiawei New materials GmbH.

Comparative example 2

This example provides an alkali-free liquid quick-setting admixture, which is prepared in the same manner as in example 1, except that: ethylene glycol is used for replacing dimethyl sulfoxide, and other components, the using amount and the preparation method are not changed.

Comparative example 3

This example provides an alkali-free liquid quick-setting admixture, which is prepared in the same manner as in example 1, except that: dimethyl sulfoxide is not added, and other components, the use amount and the preparation method are not changed.

The performance data for the above examples and comparative examples are shown in table 1. The method for testing the solid content is executed according to GB/T8077-. The method for testing the freezing resistance at the temperature of minus 20 ℃ is self-simulation, and comprises the following specific steps: and (3) standing the accelerator in an environment of-20 ℃, and observing the coagulation, layering, crystallization and other conditions of the accelerator every day for 30 days continuously.

Table 1 results of performance test of examples and comparative examples

As can be seen from the data in Table 1, the alkali-free quick-setting admixture for antifreeze liquid can be stably stored for 30 days at-20 ℃ without performance change, and the performance of the alkali-free quick-setting admixture completely meets the requirement of the alkali-free quick-setting admixture.

And (4) analyzing results:

according to comparative examples 1-3 and examples 1-3, the addition of dimethyl sulfoxide can obviously improve the freezing resistance of the alkali-free setting accelerator, and the excessive content of dimethyl sulfoxide (DMSO) has no obvious influence on the performance of the freezing-resistant alkali-free setting accelerator, but can obviously improve the cost of the setting accelerator; and a small DMSO content deteriorates the fluidity of the antifreeze type alkali-free accelerator in a low temperature state. According to example 4, it can be seen that dimethylformamide and DMSO have no significant effect on the performance of the antifreeze alkali-free accelerator. As can be seen from example 5, adding too much aluminum sulfate at a time makes part of the aluminum sulfate unreacted, and decreases its stability in a low temperature state.

Compared with the traditional low-alkali accelerating agent sold in the market, the low-alkali accelerating agent can be kept at the temperature of 20 ℃ below zero without layering and crystallization, has better fluidity, can be directly sprayed without freezing after being transported to a construction site in a low-temperature environment, and can ensure the stability of the accelerating agent. The traditional antifreeze component glycol can correspondingly improve the early strength of cement mortar when the addition amount is less, but the antifreeze alkali-free quick setting agent meeting the antifreeze property of minus 20 ℃ needs higher glycol content, so that the strength of the mortar is extremely low, and the rebound rate and the construction efficiency during site construction are difficult to ensure. If no DMSO is added, the whole system has less anti-freezing components, and for aluminum isopropoxide, aluminum hydroxide precipitates can be quickly hydrolyzed after being dissolved in water, so that the system stability becomes extremely poor.