CN103819114B - The sprayed concrete preparation method of low alkali polymer high efficiency liquid accelerating agent - Google Patents

Abstract

The invention discloses a preparation method of a low-alkali polymer high-efficiency liquid accelerator for shotcrete, which is realized through the following steps: 1) preparation of aluminate mother liquor; 2) preparation of modifier; 3) low Preparation of alkali polymer high-efficiency liquid quick-setting agent; the beneficial effects of the invention are: the low-alkali polymer high-efficiency liquid quick-setting agent disclosed by the invention is uniform and stable, has strong adaptability, and the dosage is 2% to 4% of the cement mass , the initial setting time is within 2 minutes, the final setting time is within 5 minutes, and the strength loss of concrete in the later stage is within 10%. Using this liquid accelerator can effectively reduce the amount of dust and rebound in shotcrete construction and improve the strength of shotcrete .

Description

Preparation method of low-alkali polymer high-efficiency liquid quick-setting agent for shotcrete

technical field

The invention relates to the field of building materials, in particular to a preparation method of a low-alkali polymer high-efficiency liquid quick-setting agent for shotcrete.

Background technique

Shotcrete technology is widely used in surrounding rock support in geotechnical engineering and underground engineering. Accelerator is an indispensable admixture in shotcrete. It can make cement harden quickly, reduce rebound loss, and prevent shotcrete from The shedding caused by gravity improves its adaptability to use in wet or water-bearing rock formations, and produces higher early strength, increasing the thickness of a shot, and its performance has a greater impact on shotcrete.

Accelerators are mainly divided into powder accelerators and liquid accelerators. Powder accelerators are mostly used in dry shotcrete, and liquid accelerators are mainly used in wet shotcrete. Traditional accelerators are mostly powder accelerators with high alkalinity, which have a great impact on the strength loss of shotcrete in the later stage, and at the same time pose a certain threat to the health of construction workers. At present, the accelerator is developing towards a low-alkali (no-alkali) and liquid state. The earliest abroad is the Sika (Sika) quick-setting agent developed by Switzerland and Austria. The main component of this quick-setting agent is sodium silicate, which is a tasteless liquid that has a strong corrosive effect on the skin of the human body. In the 1970s, accelerators with aluminates and carbonates as the main components appeared successively, which were called traditional alkaline accelerators. Nowadays, some alkali-free accelerators have been developed abroad, but they are expensive.

At present, most of the projects in our country are still using the tidal spraying process, which uses powdered accelerator. During the spraying process, there are defects such as a large amount of dust, slumping and rebounding, which have a great impact on the construction. . When the powdery accelerator is added, it is dispersed unevenly, causing a lot of waste and serious loss of concrete strength in the later stage. Domestically produced liquid accelerators are unstable in quality, poor in adaptability, high in dosage, generally 6% to 10%, and strong in alkalinity, causing great harm to the health of construction workers. Moreover, the liquid accelerators currently produced in my country have single performance and cannot meet the requirements of shotcrete in various aspects, such as the strength of concrete, adhesion with surrounding rock, rebound and dust. The effect of accelerators is closely related to the mineral components and content in cement. However, the production of cement is affected by many factors such as raw materials and production processes, and the mineral composition varies significantly. In my country, ordinary Portland cement can contain no more than 20% inactive admixtures, and there are many kinds of admixtures. Therefore, the adaptability of liquid accelerators to cement is very prominent, which seriously affects its use in shotcrete. in the application.

Contents of the invention

In view of the above-mentioned prior art, the present invention provides a method for preparing a low-alkali polymer high-efficiency liquid quick-setting agent for shotcrete. The prepared liquid quick-setting agent has strong adaptability to cement and can effectively reduce the amount of time spent in shotcrete construction. At the same time, the addition of low alkalinity and organic water reducer can improve the workability and later strength of shotcrete, and the liquid accelerator prepared by the invention has low dosage but high efficiency.

The present invention is achieved through the following technical solutions:

The preparation method of the low-alkali polymer high-efficiency liquid quick-setting agent for shotcrete is realized through the following steps:

1) Preparation of aluminate mother liquor

Dissolve sodium hydroxide or potassium hydroxide in water, heat to 120°C, add aluminum hydroxide, stir and react for 2-3 hours to obtain aluminate mother liquor; when the raw materials are potassium hydroxide and aluminum hydroxide, the hydroxide The mass ratio of potassium to the whole mother liquor is 30% to 40%, the mass ratio of aluminum hydroxide is 35% to 45%, the balance is water, and the molar ratio of potassium to aluminum is 1.1:1 to 1.5:1; When the raw materials are sodium hydroxide and aluminum hydroxide, the mass ratio of sodium hydroxide to the whole mother liquor is 26%-35%, the mass ratio of aluminum hydroxide is 40%-48%, the balance is water, and the sodium and aluminum elements The molar ratio is 1.1:1 to 1.5:1; when the raw materials are potassium hydroxide, sodium hydroxide and aluminum hydroxide, the mass ratio of potassium hydroxide is 10% to 25%, and that of sodium hydroxide is 10% to 25%. Aluminum hydroxide is 35% to 50%, the balance is water, and the molar ratio of the sum of the moles of potassium and sodium to the aluminum element is 1.1:1 to 1.5:1;

2) Preparation of modifier

Dissolve sodium carbonate in water, heat to 70°C-80°C, then add sodium silicate, react for 0.5h, and form a transparent solution to obtain the modifier, wherein the mass ratio of sodium carbonate to the entire modifier is 13% ～25%, the mass proportion of sodium silicate is 20%～40%, and the balance is water;

3) Preparation of low-alkali polymer high-efficiency liquid accelerator

Add the aluminate mother liquor obtained in step 1) into a three-necked flask, perform high-speed shear stirring at 500rpm/min, and simultaneously add the modifier prepared in step 2) to obtain a mixed solution. The modifier and aluminate The mass ratio of the mother liquor is 1:1 to 1:3. When the mixed liquor appears colloid, add 3% to 6% of the mass of the mixed liquor and a 2% to 5% stabilizer to continue the reaction for 1 ~2h, when the mixed liquid turns into a transparent solution, the low-alkali polymer high-efficiency liquid quick-setting agent is obtained.

The organic polymer is a mixture of a thickener, an organic water reducer and a swellable polymer with a mass ratio of 1:1:1, in order to meet the performance requirements of shotcrete in various aspects, such as reducing the The amount of rebound and dust can improve the strength of concrete in the later stage.

The thickener is polyacrylamide.

Preferably, the organic water reducer is sulfonated melamine formaldehyde resin with a concentration of 40%.

The swellable polymer is methylcellulose, hydroxyethylcellulose or hydroxypropylcellulose.

The stabilizer is gluconic acid and glycolic acid with a mass ratio of 1:1 to 2:1. The function of gluconic acid is to prevent aluminum hydroxide from precipitating out of the solution, and the glycolic acid plays a stabilizing role.

The purity of the potassium hydroxide, sodium hydroxide and aluminum hydroxide is greater than 98%.

The temperature of modifier titration in step 3) is controlled at 40-60°C.

The preparation of the modifying agent is to reduce the pH value of the aluminate mother liquor, avoid concrete alkali-aggregate reaction, and reduce the strength loss of sprayed concrete in the later stage.

The present invention has following positive effect to shotcrete:

1. In accordance with the standard requirements of JC477-2005 "Accelerators for Shotcrete", conduct a slurry test on the cement. The initial setting time of the liquid accelerator is lower at a lower dosage (2% to 4% of the cement mass). Within 2 minutes, the final setting time is within 5 minutes; the cement mortar test was carried out using this liquid accelerator, and the strength of 1 day was determined to be 12.8MPa, and the strength ratio of 28 days was above 90%;

2. The use of aluminate modifier can effectively control the setting time of the liquid accelerator, and at the same time reduce the alkalinity of the aluminate mother liquor to meet the requirement of low alkalinity, and the pH value is 9-11;

3. The addition of organic high molecular polymers can improve the adaptability of the quick-setting agent and cement, improve the performance of shotcrete in all aspects, and reduce the amount of rebound and dust in spraying construction;

4. The liquid quick-setting agent has good quick-setting effect, strong stability, no precipitation and crystallization, non-toxic, no irritating smell, and will not cause harm to the construction personnel. It is mainly used in shotcrete technology and is widely used It is used in tunnel engineering, mining construction engineering, slope engineering and building reinforcement.

detailed description

The present invention will be further described below in conjunction with embodiment.

Example 1

The preparation method of low-alkali polymer high-efficiency liquid accelerator for shotcrete is realized through the following steps: 1) Preparation of aluminate mother liquor

Add 35% potassium hydroxide and 45% aluminum hydroxide to 20% water by mass, and stir with an electric stirring bar for 3 hours at a temperature of 120°C to prepare an aluminate mother liquor;

2) Preparation of modifier

Dissolve 20% sodium carbonate in water, heat to 70°C, then add 40% sodium silicate, react for 0.5h, and form a transparent solution, which is the modifier;

3) Preparation of low-alkali polymer high-efficiency liquid accelerator

Add the aluminate mother liquor obtained in step 1) into a three-necked flask, perform high-speed shear stirring at 500rpm/min, and simultaneously add the modifier prepared in step 2) to obtain a mixed solution. The modifier and aluminate The mass ratio of the mother liquor is 1:2, and the temperature is 60°C. When colloid appears in the mixed liquor, 3% high molecular weight polymer, 1% glycolic acid and 2% gluconic acid are added to the mixed liquor, among which organic The high-molecular polymer is polyacrylamide with a mass ratio of 1:1:1, sulfonated melamine-formaldehyde resin and methylcellulose with a concentration of 40%, and the reaction is continued for 1 hour. When the mixed solution becomes a transparent solution, that is, The low-alkali polymer high-efficiency liquid accelerator can be obtained. Example 2

The preparation method of the low-alkali polymer high-efficiency liquid quick-setting agent for shotcrete is realized through the following steps:

1) Preparation of aluminate mother liquor

Add 35% potassium hydroxide and 45% aluminum hydroxide to 20% water by mass, and stir with an electric stirring bar for 3 hours at a temperature of 120°C to prepare an aluminate mother liquor;

2) Preparation of modifier

Dissolve 16% sodium carbonate in water, heat to 70°C, then add 30% sodium silicate, react for 0.5h, and form a transparent solution, which is the modifier;

3) Preparation of low-alkali polymer high-efficiency liquid accelerator

Add the aluminate mother liquor obtained in step 1) into a three-necked flask, perform high-speed shear stirring at 500rpm/min, and simultaneously add the modifier prepared in step 2) to obtain a mixed solution. The modifier and aluminate The mass ratio of the mother liquor is 1:1, and the temperature is 50°C. When colloid appears in the mixed liquor, 3% high molecular weight polymer, 1% glycolic acid and 2% gluconic acid are added to the mixed liquor, wherein the organic The high-molecular polymer is polyacrylamide with a mass ratio of 1:1:1, sulfonated melamine-formaldehyde resin and methylcellulose with a concentration of 40%, and the reaction is continued for 1 hour. When the mixed solution becomes a transparent solution, that is, The low-alkali polymer high-efficiency liquid accelerator can be obtained.

Example 3

The preparation method of the low-alkali polymer high-efficiency liquid quick-setting agent for shotcrete is realized through the following steps:

1) Preparation of aluminate mother liquor

Add 30% sodium hydroxide and 45% aluminum hydroxide by mass to 25% water, and stir with an electric stirring bar for 3 hours at a temperature of 120°C to prepare an aluminate mother liquor;

2) Preparation of modifier

Dissolve 16% sodium carbonate in water, heat to 70°C, then add 30% sodium silicate, react for 0.5h, and form a transparent solution, which is the modifier;

3) Preparation of low-alkali polymer high-efficiency liquid accelerator

Add the aluminate mother liquor obtained in step 1) into a three-necked flask, perform high-speed shear stirring at 500rpm/min, and simultaneously add the modifier prepared in step 2) to obtain a mixed solution. The modifier and aluminate The mass ratio of the mother liquor is 1:1, and the temperature is 40°C. When colloid appears in the mixed liquor, 4.5% high molecular weight polymer, 1% glycolic acid and 2% gluconic acid are added to the mixed liquor. The high-molecular polymer is polyacrylamide with a mass ratio of 1:1:1, sulfonated melamine-formaldehyde resin and methylcellulose with a concentration of 40%, and the reaction is continued for 1 hour. When the mixed solution becomes a transparent solution, that is, The low-alkali polymer high-efficiency liquid accelerator can be obtained.

Example 4

The preparation method of the low-alkali polymer high-efficiency liquid quick-setting agent for shotcrete is realized through the following steps:

1) Preparation of aluminate mother liquor

Add 20% potassium hydroxide, 15% sodium hydroxide and 45% aluminum hydroxide to 20% water by mass, and stir with an electric stirring rod for 3 hours at a temperature of 120°C to prepare aluminate mother liquor ;

2) Preparation of modifier

Dissolve 25% sodium carbonate in water, heat to 70°C, then add 40% sodium silicate, react for 0.5h, and form a transparent solution, which is the modifier;

3) Preparation of low-alkali polymer high-efficiency liquid accelerator

Add the aluminate mother liquor obtained in step 1) into a three-necked flask, perform high-speed shear stirring at 500rpm/min, and simultaneously add the modifier prepared in step 2) to obtain a mixed solution. The modifier and aluminate The mass ratio of the mother liquor is 1:2, and the temperature is 60°C. When colloid appears in the mixed liquor, 4.5% high molecular weight polymer, 1% glycolic acid and 2% gluconic acid are added to the mixed liquor. The high-molecular polymer is polyacrylamide with a mass ratio of 1:1:1, sulfonated melamine-formaldehyde resin and methylcellulose with a concentration of 40%, and the reaction is continued for 1 hour. When the mixed solution becomes a transparent solution, that is, The low-alkali polymer high-efficiency liquid accelerator can be obtained.

The present invention has all obtained satisfactory technical effect through test and probation, and effective test data is as follows:

According to the requirements of JC477-2005 "Accelerators for Shotcrete", test the setting time of cement paste and the compressive strength of cement mortar. Wherein, the dosage of the liquid quick-setting agent is calculated according to the percentage of cement weight, and the liquid quick-setting agent used is the product prepared in Examples 1-4, and the numbers are L-1, L-2, L-3, L-4 respectively.

Determination of setting time of cement slurry:

Cement 400g

155g of water

Determination of compressive strength of cement mortar:

Cement 900g

Standard sand 1350g

450g of water

The test results are shown in Table 1:

Table 1 The application effect of the liquid accelerator

It can be seen from the table that the liquid accelerator can meet the requirements of first-class products in JC477-2005 "Accelerators for Shotcrete", and it also has excellent quality in field applications, which can effectively improve the performance of shotcrete in all aspects. performance.

Claims (5)

1. a preparation method of low-alkali polymer high-efficiency liquid quick-setting agent for shotcrete, is characterized in that, is realized through the following steps: 1) Preparation of aluminate mother liquor Dissolve sodium hydroxide or potassium hydroxide in water, heat to 120°C, add aluminum hydroxide, stir and react for 2-3 hours to obtain aluminate mother liquor; when the raw materials are potassium hydroxide and aluminum hydroxide, the hydroxide The mass ratio of potassium to the whole mother liquor is 30%-40%, the mass ratio of aluminum hydroxide is 35%-45%, the balance is water, and the molar ratio of potassium to aluminum is 1.1:1-1.5:1; When the raw materials are sodium hydroxide and aluminum hydroxide, the mass ratio of sodium hydroxide to the whole mother liquor is 26% to 35%, the mass ratio of aluminum hydroxide is 40% to 48%, the balance is water, and the sodium and aluminum elements The molar ratio is 1.1:1～1.5:1; when raw materials are potassium hydroxide, sodium hydroxide and aluminum hydroxide, the mass ratio of potassium hydroxide is 10%～25%, and sodium hydroxide is 10%～25%, Aluminum hydroxide is 35% to 50%, the balance is water, and the molar ratio of the sum of the moles of potassium and sodium to the aluminum element is 1.1:1 to 1.5:1; 2) Preparation of modifier Dissolve sodium carbonate in water, heat to 70°C-80°C, then add sodium silicate and react for 0.5h to form a transparent solution to obtain the modifier, wherein the mass ratio of sodium carbonate to the entire modifier is 13%. ～25%, the mass proportion of sodium silicate is 20%～40%, and the balance is water; 3) Preparation of low-alkali polymer high-efficiency liquid accelerator The aluminate mother liquor obtained in step 1) is subjected to high-shear stirring at 500rpm/min, and simultaneously the modifier obtained in step 2) is titrated to obtain a mixed liquor, and the mass ratio of the modifier to the aluminate mother liquor is 1:1～1:3, when the mixed solution appears colloid, add 3%～6% high molecular polymer and 2%～5% stabilizer of the mixed solution, continue to react for 1～2h, wait for When the mixed solution becomes a transparent solution, the low-alkali polymer high-efficiency liquid quick-setting agent is obtained; The high molecular polymer is a mixture of a thickener, an organic water reducer and a swellable polymer with a mass ratio of 1:1:1; The stabilizer is gluconic acid and glycolic acid with a mass ratio of 1:1 to 2:1; The purity of the potassium hydroxide, sodium hydroxide and aluminum hydroxide is greater than 98%; The temperature of modifier titration in the step 3) is controlled at 40-60°C. 2. the preparation method of sprayed concrete as claimed in claim 1 is characterized in that, described thickener is polyacrylamide. 3. the preparation method of sprayed concrete as claimed in claim 1 is characterized in that, organic water reducer is the sulfonated melamine formaldehyde resin that concentration is 40%. 4. the preparation method of low-alkali polymer high-efficiency liquid accelerator for shotcrete as claimed in claim 1, is characterized in that, described swellable polymer is methyl cellulose, hydroxyethyl cellulose or hydroxypropyl cellulose. 5. A low-alkali polymer high-efficiency liquid quick-setting agent for shotcrete prepared by the method according to any one of claims 1 to 4.