CN108675672B - Concrete applied to alpine and high-altitude areas, air entraining agent and preparation method - Google Patents

Abstract

The invention provides a concrete, an air-entraining agent and a preparation method applied in high cold and high altitude areas, which are prepared from the following raw materials: triterpene saponin solution is 92% to 95%, and modified polybutadiene resin is 1.8% to 95%. 2.8%, modified polyacrylamide is 0.7% to 0.95%, sodium carbonate is 2.5% to 4.25%, and the sum of the parts by weight of the raw materials is 100%. Compared with the conventional triterpene saponin air-entraining agent, the air-entraining agent of the present invention is added with water-soluble resin-modified polybutadiene resin and water-soluble ionic polymer-modified polyacrylamide. Because the sugar chain of triterpenoid saponin itself has strong hydrophilicity, it can be combined with modified polyacrylamide, improve the strength of the bubble wall, stabilize the bubble and reduce the pore size of the bubble, increase the viscosity and strength of the bubble film, ensure The liquid film after bubble formation has sufficient continuity and elasticity.

Description

Concrete, air-entraining agent and preparation method used in high-cold and high-altitude areas

technical field

The invention relates to the field of building materials in the field of concrete air-entraining agents, in particular to a concrete, an air-entraining agent and a preparation method for use in high-cold and high-altitude areas.

Background technique

Air-entraining agent can make concrete generate a large number of uniform, stable and closed micro-bubbles during the mixing process, improve the workability of concrete, and can still retain micro-bubbles after concrete is hardened. Its main function is to improve the impermeability of concrete. properties, frost resistance, salt frost denudation resistance and durability.

Under the alpine and high-altitude climate conditions, the temperature difference between day and night is large and the air pressure is low, and the freeze-thaw damage of concrete is more serious than that in other areas. The introduction of tiny closed air bubbles into concrete by adding air-entraining agent is a common method to improve the frost resistance of concrete. measure. However, under the condition of low air pressure, the air content of the fresh concrete will decrease linearly with the ambient air pressure. When the ambient air pressure drops to 50kPa, the air content of the concrete will decrease by about 40%. At the same time, the pore structure parameters of fresh hardened concrete under low pressure conditions are generally inferior to those under normal pressure conditions, and its bubble stability is also poor. As a result, the air-entraining ability of ordinary air-entraining agents is significantly reduced under high cold and high-altitude conditions, and the air content of fresh concrete cannot meet the requirements for use, and there are many problems such as large bubbles, short defoaming time, and poor bubble stability.

SUMMARY OF THE INVENTION

In view of the deficiencies in the prior art, the purpose of the present invention is to provide a concrete air-entraining agent applied in high-cold and high-altitude areas and a preparation method thereof, so as to solve the problem that the air-entraining agent in the prior art cannot be applied to high-cold and high-altitude areas. technical problem.

In order to solve the above-mentioned technical problems, the application adopts the following technical solutions to realize:

A concrete air-entraining agent used in high-cold and high-altitude areas, comprising the following raw materials: triterpene saponin solution, water-soluble resin, water-soluble ionic polymer and modifier;

Described water-soluble resin is modified polybutadiene resin;

The water-soluble ionic polymer is modified polyacrylamide;

The modifier is sodium carbonate.

The present invention also has the following technical features:

Specifically, in parts by weight, it is prepared from the following raw materials: triterpene saponin solution is 92% to 95%, modified polybutadiene resin is 1.8% to 2.8%, and modified polyacrylamide is 0.7% to 0.95% %, sodium carbonate is 2.5% to 4.25%, and the sum of the parts by weight of the raw materials is 100%.

Preferably, in parts by weight, it is prepared from the following raw materials: 93% of triterpenoid saponin solution, 2.2% of modified polybutadiene resin, 0.85% of modified polyacrylamide, and 3.95% of sodium carbonate.

Specifically, the number-average molecular weight of the modified polybutadiene resin is 1,000-30,000; the number-average molecular weight of the modified polyacrylamide is 10,000-40,000.

The present invention also protects a method for preparing a concrete air-entraining agent applied in high-cold and high-altitude areas, the method adopts the above-mentioned formula of the concrete air-entraining agent applied in high-cold and high-altitude areas, and specifically includes the following steps:

Step 1, prepare the preparation of triterpene saponin solution:

Weigh the acacia, remove the surface dirt with a cleaning solution, expose the washed acacia in the sun for 3 to 5 days, and pulverize the dried acacia with a pulverizer to obtain acacia powder; put the acacia powder in ethanol and acetone. The mixture was extracted at room temperature for 2 to 4 hours, and the residue was filtered to obtain a triterpenoid saponin solution;

The volume ratio of described ethanol and acetone is 1:2;

Described every 1000g acacia correspondingly adds the mixture of 15～25kg ethanol and acetone;

Step 2, prepare modified polybutadiene resin:

First, the butadiene monomer and the acidic catalyst acetic acid are added to the reaction kettle for polyaddition reaction, the heating time is 2 to 3 hours, and the temperature is 200 to 300 ° C to obtain a polybutadiene solution, followed by adding rosin, hydrogen peroxide and Lignin, heated at a temperature of 150 to 200 ° C for 1 to 2 hours to obtain a modified polybutadiene resin;

In parts by weight: 30 parts of butadiene monomer, 3 to 5 parts of acetic acid, 50 to 60 parts of rosin, and 8 to 10 parts of lignin.

Step 3. Preparation of modified polyacrylamide:

Add acrylonitrile, butanediol and water into the polymerization tank, and add the initiator potassium persulfide, and carry out the polymerization reaction by light irradiation. The irradiation temperature is 75-100°C, and the reaction time is 3-4 hours, and the modified polyacrylamide is formed by polymerization;

In parts by weight: acrylonitrile is 10, butanediol is 3-5, and water is 80-100.

Step 4: Mix the triterpenoid saponin solution and the modified polybutadiene resin uniformly, put it into the high pressure reaction kettle, heat it to 1 to 2 hours, keep the temperature at 95 to 100 ° C, and then pump the air in the reaction kettle to a pressure of 1～10Pa, vacuum removes air and low boiling components in the reaction kettle to obtain mixed solution A;

Step 5. Add modified polyacrylamide to mixed solution A, and stir for 20 to 30 min in a constant temperature water bath at 40 to 50°C to obtain mixed solution B;

Step 6: Add sodium carbonate to the mixed solution B under normal temperature and pressure for 15-35 minutes to prepare a concrete air-entraining agent.

The present invention also protects a concrete for use in high-cold and high-altitude areas, which, in parts by weight, includes a concrete main body and an air-entraining agent, and the added amount of the air-entraining agent is 0.01% of the concrete main body;

Specifically, the air-entraining agent is the concrete air-entraining agent used in the high-cold and high-altitude areas as described above.

Specifically, the concrete main body, in parts by weight, is composed of the following raw materials: 360 parts of cement, 160 parts of water, 725 parts of sand, 1135 parts of crushed stone, and 2.16 parts of water reducer.

Compared with the prior art, the present invention has the following beneficial technical effects:

(I) The air-entraining agent of the present invention can reduce the surface tension of the solution, generate closed and independent micro-bubbles, have long foam stabilization time, high foaming multiples, small spacing, and have good working performance under high cold and high altitude conditions.

(II) Compared with the conventional triterpene saponin air-entraining agent, the air-entraining agent of the present invention contains water-soluble resin-modified polybutadiene resin and water-soluble ionic polymer-modified polyacrylamide. Because the sugar chain of triterpenoid saponin itself has strong hydrophilicity, it can be combined with modified polyacrylamide, improve the strength of the bubble wall, stabilize the bubble and reduce the pore size of the bubble, increase the viscosity and strength of the bubble film, ensure The liquid film after bubble formation has sufficient continuity and elasticity. The addition of the modified polybutadiene resin can combine with the aglycones in the triterpene saponins, so that the surface tension of the liquid can be significantly reduced, thereby ensuring that the air-entraining agent can generate a sufficient amount of air bubbles.

(III) The micro-bubbles introduced by the air-entraining agent of the present invention can cut off the capillary passage and reduce the capillary action, thereby improving the impermeability of concrete. These micro-pores can release the ice crystal expansion pressure in the capillary during the freezing process, thereby avoiding the generation of destructive pressure, reducing and preventing the destructive effect of freezing and thawing, and improving the frost resistance and durability of concrete when working in high-cold and high-altitude conditions.

(V) The air-entraining agent of the present invention uses natural plant acacia as the main raw material, the material acquisition cost is lower, and the preparation process is simpler than the traditional preparation method.

The specific content of the present invention will be further explained in detail below in conjunction with the embodiments.

Detailed ways

Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent transformations made on the basis of the technical solutions of the present application fall into the protection scope of the present invention.

Example 1:

The present embodiment provides a concrete air-entraining agent applied in high cold and high altitude areas, which is made of the following raw materials in parts by weight: triterpene saponin solution is 93%, modified polybutadiene resin is 2.2%, Modified polyacrylamide is 0.85% and sodium carbonate is 3.95%.

The number average molecular weight of the modified polybutadiene resin is 1,000-30,000; the number-average molecular weight of the modified polyacrylamide is 10,000-40,000.

The preparation method of the concrete air-entraining agent applied to the high-cold and high-altitude area of the present embodiment comprises the following steps:

Step 1, prepare the preparation of triterpene saponin solution:

Weigh the acacia, remove the surface dirt with a cleaning solution, expose the washed acacia in the sun for 3 to 5 days, and pulverize the dried acacia with a pulverizer to obtain acacia powder; put the acacia powder in ethanol and acetone. The mixture was extracted at room temperature for 2 to 4 hours, and the residue was filtered to obtain a triterpenoid saponin solution;

The volume ratio of described ethanol and acetone is 1:2;

Described every 1000g acacia correspondingly adds the mixture of 15～25kg ethanol and acetone;

Step 2, prepare modified polybutadiene resin:

First, the butadiene monomer and the acidic catalyst acetic acid are added to the reaction kettle for polyaddition reaction, the heating time is 2 to 3 hours, and the temperature is 200 to 300 ° C to obtain a polybutadiene solution, followed by adding rosin, hydrogen peroxide and Lignin, heated at a temperature of 150 to 200 ° C for 1 to 2 hours to obtain a modified polybutadiene resin;

In parts by weight: 30 parts of butadiene monomer, 3 to 5 parts of acetic acid, 50 to 60 parts of rosin, and 8 to 10 parts of lignin.

Step 3. Preparation of modified polyacrylamide:

Add acrylonitrile, butanediol and water into the polymerization tank, and add the initiator potassium persulfide, and carry out the polymerization reaction by light irradiation. The irradiation temperature is 75-100°C, and the reaction time is 3-4 hours, and the modified polyacrylamide is formed by polymerization;

In parts by weight: acrylonitrile is 10, butanediol is 3-5, and water is 80-100.

Step 4: Mix the triterpenoid saponin solution and the modified polybutadiene resin uniformly, put it into the high pressure reaction kettle, heat it to 1 to 2 hours, keep the temperature at 95 to 100 ° C, and then pump the air in the reaction kettle to a pressure of 1～10Pa, vacuum removes air and low boiling components in the reaction kettle to obtain mixed solution A;

Step 5. Add modified polyacrylamide to mixed solution A, and stir for 20 to 30 min in a constant temperature water bath at 40 to 50°C to obtain mixed solution B;

Step 6: Add sodium carbonate to the mixed solution B under normal temperature and pressure for 15-35 minutes to prepare a concrete air-entraining agent.

For the application effect of the concrete air-entraining agent prepared in this example, please refer to the application example.

Example 2:

The present embodiment provides a concrete air-entraining agent for use in high cold and high altitude areas, which is prepared by the following raw materials in parts by weight: the triterpene saponin solution is 92% to 95%, and the modified polybutadiene resin is 1.8% to 2.8%, 0.7% to 0.95% of modified polyacrylamide, 2.5% to 4.5% of sodium carbonate, and the sum of the parts by weight of the raw materials is 100%.

The present embodiment provides a concrete air-entraining agent for use in high cold and high altitude areas, which is made of the following raw materials in parts by weight: triterpene saponin solution is 92%, modified polybutadiene resin is 2.8%, Modified polyacrylamide is 0.95% and sodium carbonate is 4.25%.

The modified polybutadiene resin was the same as in Example 1.

Modified polyacrylamide is the same as Example 1.

The preparation method of this example is basically the same as that of Example 1.

The application effect of the concrete air-entraining agent prepared in this example is basically the same as that in Example 1.

Example 3:

The present embodiment provides a concrete air-entraining agent for use in high cold and high altitude areas, which is made of the following raw materials in parts by weight: triterpene saponin solution is 95%, modified polybutadiene resin is 1.8%, Modified polyacrylamide is 0.7% and sodium carbonate is 2.5%.

The modified polybutadiene resin was the same as in Example 1.

Modified polyacrylamide is the same as Example 1.

The preparation method of this example is basically the same as that of Example 1.

The application effect of the concrete air-entraining agent prepared in this example is basically the same as that in Example 1.

Example 4:

The present embodiment provides a concrete for use in high-cold and high-altitude areas, which, in parts by weight, includes a concrete main body and an air-entraining agent, and the added amount of the air-entraining agent is 0.01% of the concrete main body;

The concrete main body, in parts by weight, is composed of the following raw materials: 360 parts of cement, 160 parts of water, 725 parts of sand, 1135 parts of crushed stone, and 2.16 parts of water reducing agent.

in:

The air-entraining agent used in Example 1 is the concrete air-entraining agent used in high-cold and high-altitude areas.

The water reducing agent is a conventional water reducing agent in the field.

The concrete of this embodiment can be prepared by the preparation method of conventional concrete.

See the application example for the concrete performance test results of this embodiment.

Application example:

The cement selected in this test is P.O 42.5; the sand is medium sand, the fineness modulus is 2.6, and the mud content is 1.1%; the stone is limestone crushed stone with a particle size of 5-20mm, and the mud content is 0.7%; the water is ordinary drinking water. Concrete mixing was completed in a low-pressure simulation box, and the air pressure was set to 50kpa.

In parts by weight, the concrete proportions are shown in Table 1 below.

Table 1 Concrete mix ratio

Control group 1: Concrete without air-entraining agent added in the above mix ratio;

Control group 2: concrete with 0.01% rosin thermopolymer air-entraining agent added in the above mixing ratio;

Control group 3: concrete with 0.01% polyether air-entraining agent added in the above mixing ratio;

Control group 4: concrete with 0.01% conventional triterpene saponin air-entraining agent added in the above mixing ratio;

Application example: the concrete with 0.01% of the high-cold and high-altitude air-entraining agent of Example 1 of the present invention added in the above mixing ratio.

The air content test and 300 freeze-thaw cycle tests were carried out on the fresh concrete in the above experiments, and the specific test methods for measuring the dynamic elastic modulus and mass loss refer to the "Concrete Test Regulations", and the results are shown in Table 2 below.

Table 2 Test results

It can be seen from Table 2 that under the low pressure conditions simulated by the test chamber, the air content of the concrete added with air-entraining agents in high-cold and high-altitude areas in the control group is significantly higher than that with other types of air-entraining agents. The high-cold and high-altitude air-entraining agent has good air-entraining ability under low pressure conditions. The results of the freeze-thaw cycle test showed that the relative dynamic elastic modulus of the first three groups of concrete without adding or adding other air-entraining agents after 300 freeze-thaw cycles dropped to about 60%, and the mass loss was close to 5%, indicating that the internal structure of the concrete has been been destroyed. Although the relative dynamic elastic modulus and mass loss in control 4 are slightly better than those in the first three groups, the dynamic elastic modulus drops to about 80%, and the mass loss is close to 2%, indicating that the concrete structure of control group 4 has also suffered obvious damage. . However, the concrete added with high-altitude and high-altitude air-entraining agent undergoes 300 freeze-thaw cycles, and the loss of dynamic elastic modulus and quality is small, the relative dynamic elastic modulus can be maintained at about 90%, and the mass loss is about 1%. It was not damaged, indicating that the frost resistance of concrete mixed with high-cold and high-altitude air-entraining agent is also significantly better than that of other types of air-entraining agents.

To sum up, the liquid air-entraining agent prepared by the present invention and applied in high-cold and high-altitude areas can generate a large number of uniform and stable air bubbles, improve the internal structure of concrete, thereby improving the durability and service life of concrete, and has significant economic benefits and advantages. strategic significance.

Claims (6)

1. A concrete air entraining agent applied to alpine and high-altitude areas is prepared from the following raw materials in parts by weight: the triterpenoid saponin solution accounts for 92-95 percent, the modified polybutadiene resin accounts for 1.8-2.8 percent, the modified polyacrylamide accounts for 0.7-0.95 percent, the sodium carbonate accounts for 2.5-4.25 percent, and the sum of the weight parts of the raw materials is 100 percent;

the preparation method of the concrete air entraining agent applied to the alpine and high-altitude areas comprises the following steps:

step one, preparing a triterpenoid saponin solution:

weighing the gleditsia sinensis, removing dirt on the surface of the gleditsia sinensis by using cleaning liquid, exposing the cleaned gleditsia sinensis in the sun for 3-5 days, and crushing the dried gleditsia sinensis by using a crusher to obtain gleditsia sinensis powder; extracting the gleditsia sinensis powder in a mixture of ethanol and acetone at normal temperature for 2-4 hours, and filtering residues to obtain a triterpenoid saponin solution;

the volume ratio of the ethanol to the acetone is 1: 2;

adding 15-25 kg of a mixture of ethanol and acetone into each 1000g of the Chinese honeylocust correspondingly;

step two, preparing modified polybutadiene resin:

firstly, adding a butadiene monomer and an acid catalyst acetic acid into a reaction kettle for addition polymerization reaction, heating for 2-3 hours at 200-300 ℃ to obtain a polybutadiene solution, then adding rosin, hydrogen peroxide and lignin, and heating at 150-200 ℃ for 1-2 hours to obtain modified polybutadiene resin;

the weight portion is: 30 parts of butadiene monomer, 3-5 parts of acetic acid, 50-60 parts of rosin and 8-10 parts of lignin;

step three, preparing modified polyacrylamide:

adding acrylonitrile, butanediol and water into a polymerization tank, adding an initiator potassium persulfate, and performing polymerization reaction by light irradiation; irradiating at the temperature of 75-100 ℃ for 3-4 hours, and polymerizing to generate modified polyacrylamide;

the weight portion is: 10 parts of acrylonitrile, 3-5 parts of butanediol and 80-100 parts of water;

step four, mixing the triterpenoid saponin solution and the modified polybutadiene resin uniformly, then putting the mixture into a high-pressure reaction kettle, heating the mixture for 1-2 hours, keeping the temperature at 95-100 ℃, pumping air in the reaction kettle to the pressure of 1-10 Pa, and removing the air and low-boiling components in the reaction kettle in vacuum to obtain a mixed solution A;

step five, adding modified polyacrylamide into the mixed solution A, and stirring for 20-30 min in a constant-temperature water bath at 40-50 ℃ to obtain a mixed solution B;

and step six, adding sodium carbonate into the mixed solution B at normal temperature and normal pressure, and mixing for 15-35 min to obtain the concrete air entraining agent.

2. The concrete air entraining agent applied to the alpine and high-altitude areas as claimed in claim 1, which is prepared from the following raw materials in parts by weight: the triterpenoid saponin solution is 93 percent, the modified polybutadiene resin is 2.2 percent, the modified polyacrylamide is 0.85 percent, and the sodium carbonate is 3.95 percent.

3. The concrete air entraining agent applied to the alpine and high-altitude areas as claimed in claim 1, wherein the number average molecular weight of the modified polybutadiene resin is 1000-30000; the number average molecular weight of the modified polyacrylamide is 10000-40000.

4. A method for preparing a concrete air entraining agent applied to alpine and high-altitude areas, which is characterized by adopting the formula of the concrete air entraining agent applied to the alpine and high-altitude areas as claimed in any one of claims 2 to 3, and specifically comprising the following steps:

step one, preparing a triterpenoid saponin solution:

weighing the gleditsia sinensis, removing dirt on the surface of the gleditsia sinensis by using cleaning liquid, exposing the cleaned gleditsia sinensis in the sun for 3-5 days, and crushing the dried gleditsia sinensis by using a crusher to obtain gleditsia sinensis powder; extracting the gleditsia sinensis powder in a mixture of ethanol and acetone at normal temperature for 2-4 hours, and filtering residues to obtain a triterpenoid saponin solution;

the volume ratio of the ethanol to the acetone is 1: 2;

adding 15-25 kg of a mixture of ethanol and acetone into each 1000g of the Chinese honeylocust correspondingly;

step two, preparing modified polybutadiene resin:

firstly, adding a butadiene monomer and an acid catalyst acetic acid into a reaction kettle for addition polymerization reaction, heating for 2-3 hours at 200-300 ℃ to obtain a polybutadiene solution, then adding rosin, hydrogen peroxide and lignin, and heating at 150-200 ℃ for 1-2 hours to obtain modified polybutadiene resin;

the weight portion is: 30 parts of butadiene monomer, 3-5 parts of acetic acid, 50-60 parts of rosin and 8-10 parts of lignin;

step three, preparing modified polyacrylamide:

adding acrylonitrile, butanediol and water into a polymerization tank, adding an initiator potassium persulfate, and performing polymerization reaction by light irradiation; irradiating at the temperature of 75-100 ℃ for 3-4 hours, and polymerizing to generate modified polyacrylamide;

the weight portion is: 10 parts of acrylonitrile, 3-5 parts of butanediol and 80-100 parts of water;

step four, mixing the triterpenoid saponin solution and the modified polybutadiene resin uniformly, then putting the mixture into a high-pressure reaction kettle, heating the mixture for 1-2 hours, keeping the temperature at 95-100 ℃, pumping air in the reaction kettle to the pressure of 1-10 Pa, and removing the air and low-boiling components in the reaction kettle in vacuum to obtain a mixed solution A;

step five, adding modified polyacrylamide into the mixed solution A, and stirring for 20-30 min in a constant-temperature water bath at 40-50 ℃ to obtain a mixed solution B;

and step six, adding sodium carbonate into the mixed solution B at normal temperature and normal pressure, and mixing for 15-35 min to obtain the concrete air entraining agent.

5. The concrete applied to the alpine and high-altitude areas comprises a concrete main body and an air entraining agent in parts by weight, and is characterized in that the addition amount of the air entraining agent is 0.01 percent of that of the concrete main body;

the air entraining agent is the concrete air entraining agent applied to the alpine and high-altitude area according to any one of claims 1 to 3.

6. The concrete applied to the alpine and high-altitude areas as claimed in claim 5, wherein the concrete body is composed of the following raw materials in parts by weight: 360 parts of cement, 160 parts of water, 725 parts of sand, 1135 parts of broken stone and 2.16 parts of water reducing agent.