CN113429149A

CN113429149A - High early strength alkali-free liquid accelerator and preparation method thereof

Info

Publication number: CN113429149A
Application number: CN202110747753.9A
Authority: CN
Inventors: 刘建均; 杨杨
Original assignee: Chengdu Jiaxin Technology Group Co ltd
Current assignee: Chengdu Jiaxin Technology Group Co ltd
Priority date: 2021-07-02
Filing date: 2021-07-02
Publication date: 2021-09-24

Abstract

The invention discloses a high early strength alkali-free liquid accelerator and a preparation method thereof, belongs to the technical field of building materials, and solves the problem that sprayed concrete using the liquid accelerator in the prior art generally has low early strength. The high early strength alkali-free liquid accelerator provided by the invention comprises the following raw materials in percentage by mass: aluminum sulfate: 50-70%; a stabilizer: 3 to 7 percent; early strength components: 0.5-3%; inorganic acid: 0 to 6 percent; the balance being water. After 6-9% of the early strength alkali-free liquid accelerator prepared by the invention is added into sprayed concrete, the initial setting time of the sprayed concrete is less than 5 minutes, the final setting time is less than 10 minutes, the 1-day compressive strength is more than 9MPa, the 28-day compressive strength is not lost, and compared with other accelerators, the early strength is greatly increased on the premise of meeting other indexes of the GB35159 standard. The invention is suitable for improving the early strength of the sprayed concrete.

Description

High early strength alkali-free liquid accelerator and preparation method thereof

Technical Field

The invention belongs to the technical field of building materials, and particularly relates to a high early strength alkali-free liquid accelerator and a preparation method thereof.

Background

With the increasing tunnel construction projects in the construction process of high-speed railways and highways in China, higher and higher requirements are put forward on the performance of sprayed concrete. The accelerator is used as an indispensable additive for sprayed concrete, and has the functions of accelerating the setting and hardening of the sprayed concrete, reducing the rebound loss, preventing the sprayed concrete from falling off due to gravity and improving the early strength of the concrete.

The sprayed concrete is mainly divided into dry spraying and wet spraying according to the spraying technology, and the dry spraying and the wet spraying correspond to the powder accelerating agent and the liquid accelerating agent respectively. Most of the powder accelerator contains strong alkaline substances, so that the powder accelerator is extremely strong in corrosivity, easily harms constructors, and easily causes alkali-aggregate reaction of concrete, so that the strength of the concrete is reduced, the surface of the concrete is cracked, peeled or even collapsed, and further safety accidents are caused. Meanwhile, the dry spraying process has high dust concentration during construction, and seriously pollutes the surrounding atmospheric environment. The liquid accelerator can basically overcome the defects, is widely applied at home and abroad, has better uniformity and durability in wet spraying concrete, can effectively reduce the rebound quantity, and becomes the development trend of concrete spraying technology in various countries in the world.

At present, the problem of low early strength and low later strength of sprayed concrete using a liquid accelerator generally exist, and therefore, a preparation method of a high early strength alkali-free liquid accelerator is provided for solving the problem of low early strength of the sprayed concrete.

Disclosure of Invention

Aiming at the problem that sprayed concrete using a liquid accelerator in the prior art generally has low early strength, the invention provides a high early strength alkali-free liquid accelerator and a preparation method thereof, and the purpose is as follows: the early strength and the later strength of the sprayed concrete are improved.

The technical scheme adopted by the invention is as follows:

a high early strength alkali-free liquid accelerator comprises the following raw materials in percentage by mass:

aluminum sulfate: 50-70%;

a stabilizer: 3 to 7 percent;

early strength components: 0.5-3%;

inorganic acid: 0 to 6 percent;

water: the balance, make up to 100%.

Preferably, the aluminum sulfate is industrial-grade aluminum sulfate, and the content of aluminum oxide is more than or equal to 15.8%.

Preferably, the stabilizer is one or a mixture of triethanolamine and diethanolamine.

Preferably, the early strength component is one or a mixture of several of nano-crystal seed, lithium carbonate, calcium formate and urea.

Preferably, the inorganic acid is phosphoric acid.

A preparation method of a high early strength alkali-free liquid accelerator comprises the following steps:

step 1: weighing aluminum sulfate, a stabilizer, an early strength component, inorganic acid and water according to a proportion.

Step 2: adding water into a reaction kettle, heating to 60 ℃, and starting stirring at a stirring speed of not less than 100 rpm;

and step 3: adding aluminum sulfate into a reaction kettle, keeping the temperature at 60 ℃, stirring for 10-20 minutes to ensure that the aluminum sulfate is completely dissolved, wherein the stirring speed is not lower than 100rpm

And 4, step 4: adding the early strength component into a reaction kettle, keeping the temperature at 60 ℃, and stirring for 5-10 minutes to completely dissolve the early strength component, wherein the stirring speed is not lower than 100 rpm;

and 5: adding a stabilizer into a reaction kettle, keeping the temperature at 60 ℃, and stirring for 5-10 minutes to uniformly mix the stabilizer and the solution in the reaction kettle, wherein the stirring speed is not lower than 100 rpm;

step 6: adding inorganic acid into a reaction kettle, keeping the temperature at 60 ℃, and stirring for 3-5 minutes to uniformly mix the inorganic acid and the solution in the reaction kettle, wherein the stirring speed is not lower than 100 rpm;

and 7, continuing stirring for 5-10 minutes at a stirring speed of not less than 100rpm, stopping heating, and filtering the material when the temperature is reduced to 40 ℃ to obtain a finished product of the high early strength alkali-free liquid accelerator.

In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:

after 6-9% of the early strength alkali-free liquid accelerator prepared by the invention is added into sprayed concrete, the initial setting time is less than 5 minutes, the final setting time is less than 10 minutes, the 1-day compressive strength is more than 9MPa, and the 28-day compressive strength is not lost.

Detailed Description

All of the features disclosed in this specification, or all of the steps in any method or process so disclosed, may be combined in any combination, except combinations of features and/or steps that are mutually exclusive.

Example 1

The high early strength alkali-free liquid accelerator comprises the following raw materials in parts by weight:

aluminum sulfate: 55 percent of

Triethanolamine: 4 percent of

Lithium carbonate: 0.6 percent

Phosphoric acid: 5.0 percent

Water: 35.4 percent

The high early strength alkali-free setting accelerator prepared according to the mixture ratio is numbered as follows: HSC-1.

The preparation steps are as follows:

step 1: weighing aluminum sulfate, triethanolamine, lithium carbonate, phosphoric acid and water according to the proportion.

And 4, step 4: adding lithium carbonate into a reaction kettle, keeping the temperature at 60 ℃, and stirring for 5-10 minutes to completely dissolve the lithium carbonate, wherein the stirring speed is not lower than 100 rpm;

and 5: adding triethanolamine into a reaction kettle, keeping the temperature at 60 ℃, and stirring for 5-10 minutes to uniformly mix the triethanolamine with the solution in the reaction kettle, wherein the stirring speed is not lower than 100 rpm;

step 6: adding phosphoric acid into a reaction kettle, keeping the temperature at 60 ℃, and stirring for 3-5 minutes to uniformly mix the phosphoric acid and the solution in the reaction kettle, wherein the stirring speed is not lower than 100 rpm;

Example 2

aluminum sulfate: 58 percent of

Diethanolamine: 4.2 percent of

Lithium carbonate: 0.6 percent

Nano seed crystal: 0.5 percent

Phosphoric acid: 5.2 percent of

Water: 31.8 percent

The high early strength alkali-free setting accelerator prepared according to the mixture ratio is numbered as follows: HSC-2 was prepared in the same manner as in example 1.

Example 3

aluminum sulfate: 56 percent

Triethanolamine: 2 percent of

Urea: 1.5 percent

Nano seed crystal: 0.8 percent

Phosphoric acid: 1 percent of

Water: 34.4 percent

The high early strength alkali-free setting accelerator prepared according to the mixture ratio is numbered as follows: HSC-3 was prepared in the same manner as in example 1.

Example 4

aluminum sulfate: 60 percent of

Urea: 2.5 percent

Triethanolamine: 1.4 percent

Lithium carbonate: 0.4 percent

Phosphoric acid: 0.2 percent of

Water: 30.2 percent

The high early strength alkali-free setting accelerator prepared according to the mixture ratio is numbered as follows: HSC-5 was prepared in the same manner as in example 1.

Commercial accelerator comparative example 1:

the main components are as follows: aluminum sulfate: 45 percent; lithium sulfate: 1 percent; nano materials: 5 percent; organic alcohol amine: 5 percent; inorganic acid: 3.5 percent; water: 40.5 percent.

Commercial accelerator comparative example 2:

the main components are as follows: aluminum sulfate: 50 percent; magnesium sulfate: 5 percent; 1.8% of calcium formate: organic alcohol amine: 5 percent; inorganic acid: 3 percent; water: 35.5 percent.

The following table shows experimental data of the sprayed concrete when the blending amount of the high early strength alkali-free accelerator prepared by the invention is 7% and the blending amount of the accelerator sold in the market is 7%:

as can be seen from the above table, the high early strength alkali-free liquid accelerator prepared by the invention can meet the requirement of GB35159 at the doping amount of 7%, and has shorter initial setting time and final setting time, higher 1d compressive strength and 28d compressive strength compared with the commercial accelerator. The addition of the urea as the early strength agent in the embodiment examples 3 and 4 not only greatly reduces the addition of the inorganic acid, but also increases the full-term strength of the mortar test piece.

The above-mentioned embodiments only express the specific embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present application. It should be noted that, for those skilled in the art, without departing from the technical idea of the present application, several changes and modifications can be made, which are all within the protection scope of the present application.

Claims

1. The high early strength alkali-free liquid accelerator is characterized by comprising the following raw materials in percentage by mass:

aluminum sulfate: 50-70%;

a stabilizer: 3 to 7 percent;

early strength components: 0.5-3%;

inorganic acid: 0 to 6 percent;

the balance being water.

2. The high early strength alkali-free liquid accelerator as claimed in claim 1, wherein the aluminum sulfate is industrial grade aluminum sulfate, and the content of aluminum oxide is not less than 15.8%.

3. The high early strength alkali-free liquid accelerator according to claim 1, wherein the stabilizer is one or a mixture of triethanolamine and diethanolamine.

4. The high early strength alkali-free liquid accelerator as claimed in claim 1, wherein the early strength component is one or a mixture of several of nano-crystal seed, lithium carbonate, calcium formate and urea.

5. The high early strength alkali-free liquid accelerator as claimed in claim 1, wherein the inorganic acid is phosphoric acid.

6. The method for preparing the high early strength alkali-free liquid accelerator as claimed in any one of claims 1 to 5, characterized by comprising the following steps:

and step 3: adding aluminum sulfate into a reaction kettle, keeping the temperature at 60 ℃, and stirring for 10-20 minutes to ensure that the aluminum sulfate is completely dissolved, wherein the stirring speed is not lower than 100 rpm;