WO2023226892A1

WO2023226892A1 - Concrete composite admixture containing tuff powder and preparation method therefor

Info

Publication number: WO2023226892A1
Application number: PCT/CN2023/095275
Authority: WO
Inventors: 李明霞; 李家正; 石妍; 周世华; 董芸; 李杨; 闫小虎; 李响; 张亮; 蒋文广
Original assignee: 长江水利委员会长江科学院
Priority date: 2022-05-23
Filing date: 2023-05-19
Publication date: 2023-11-30
Also published as: CN115259730A; CN115259730B

Abstract

The present invention belongs to the technical field of building materials. Disclosed are a concrete composite admixture containing tuff powder and a preparation method therefor. The concrete composite admixture comprises the following components in percentage by mass: 50-70% of tuff powder and 30-50% of ultrafine powder. A preparation method for the tuff powder is as follows: mixing tuff ore with sodium hexametaphosphate, melamine and an activator, and then carrying out ball milling for 1-2 h to obtain the tuff powder. In the present invention, the tuff is mixed and milled with the melamine and the activator; the melamine can improve the milling efficiency while achieving a water reducing effect, so that the fluidity ratio of the composite admixture is improved; in addition, the activator is added during the milling, so that under the combined action of mechanical force chemical action and chemical excitation, the activity index of the composite admixture is improved, thereby ensuring the strength of concrete in all ages.

Description

A kind of concrete composite admixture containing tuff powder and its preparation method

Technical field

The invention belongs to the technical field of building materials, and specifically relates to a concrete composite admixture containing tuff powder and a preparation method thereof.

Background technique

As an important component of concrete for the main structure of civil engineering, mineral admixtures can significantly improve the workability of concrete, increase the strength and durability of concrete, and effectively reduce the cost of concrete. They have become an indispensable component of concrete cementitious materials. Traditionally commonly used mineral admixtures include industrial by-products such as fly ash, slag powder, silica fume, etc. With the rapid advancement of my country's infrastructure construction, high-quality mineral admixtures such as ore powder and fly ash are facing resource shortages and uneven regional distribution. The problem. For example, in the entire western Sichuan and Tibet regions, due to environmental protection requirements and low industrial development, traditional mineral admixtures are in very short supply in these areas. In order to meet the needs of project construction, materials such as fly ash need to be purchased and transported from other provinces, which greatly increases the time required for project construction. cost.

Research shows that igneous rock minerals have a chemical composition similar to that of fly ash. After grinding and processing it to a certain fineness, it has a certain potential hydration activity. Its chemical activity is similar to that of volcanic ash materials, fly ash, etc. , activated silica, activated alumina and calcium hydroxide react to form hydrated calcium aluminosilicate with gel properties, which can be used to produce concrete instead of fly ash. However, some igneous rock minerals contain more than 50% pores by volume. Using them as concrete admixtures will greatly increase the water demand and have a low fluidity ratio, which is not conducive to the working performance of concrete. In addition, its reactivity is low and it is not suitable for concrete work. It is conducive to the later strength development of concrete, causing problems such as slow strength growth in the later period and poor concrete density. Therefore, when igneous rock materials are used as concrete mineral admixtures, they need to be modified to effectively solve the above problems. For example, Chinese patent CN106242333A discloses a preparation method of tuff rock powder admixture, in which 1,000 parts by weight of tuff are mixed with 0.13-1.3 parts by weight of a modifier. The modifier consists of a grinding aid component and an air-entraining component. and thickening components. However, the 7d and 28d activity index of this tuff stone powder admixture is low, and its ability to improve the later strength of concrete is limited.

Therefore, in order to meet the needs of actual engineering, it is urgent to prepare a mineral admixture that can replace traditional fly ash and slag powder with low cost, simple preparation method and excellent performance.

Contents of the invention

In view of the above deficiencies in the prior art, the purpose of the present invention is to provide a concrete composite admixture containing tuff powder. The composite admixture has a high activity index and a high fluidity ratio, and can effectively improve the fluidity of fresh concrete. , improve the compressive strength of concrete.

In order to achieve the above objects, the specific technical solutions of the present invention are as follows:

A concrete composite admixture containing tuff powder, including each component in the following mass percentages: 50% to 70% tuff powder, 30% to 50% ultrafine powder;

The preparation method of the tuff powder is as follows: mix the tuff ore with sodium hexametaphosphate, melamine, and active activator, and then perform ball milling for 1 to 2 hours to obtain the tuff powder.

Grinding can exert physical activity on tuff and improve the activity index of tuff. However, after grinding tuff, the particle size decreases and the specific surface area increases. While ensuring that the thickness of the water film on the surface of the particles remains unchanged, the slurry When the same fluidity is reached, the amount of free mixing water in the slurry decreases, which causes the overall fluidity to decrease and the water demand to increase. In order to solve the above technical problems, the present invention mixes and grinds tuff with melamine and active activator. On the one hand, melamine can improve the grinding efficiency, and on the other hand, it can reduce water, thereby improving the fluidity ratio of the composite admixture. ; At the same time, active activators are added during grinding. Under the combined action of mechanical chemical action and chemical excitation, the activity index of the composite admixture is improved to ensure the strength of concrete at all ages.

At the same time, the inventor found that after grinding a single tuff, more debris is adsorbed on the surface of the large tuff particles, and as the grinding time increases, the adsorption phenomenon on the surface of the tuff particles becomes more obvious; indicating that the tuff powder has an agglomeration effect. (As shown in Figures 1-2), this will affect the grinding effect and the reactivity of the tuff powder; in the present invention, sodium hexametaphosphate is added during the tuff grinding process, and the sodium hexametaphosphate has good dispersion It can disperse the tuff powder and avoid the agglomeration effect of the tuff powder. On the one hand, it can improve the grinding efficiency, and on the other hand, it can also improve the activity index of the composite admixture.

The present invention can effectively improve the grinding efficiency by adding sodium hexametaphosphate, melamine and active activator during grinding, and at the same time effectively improve the fluidity ratio and activity index of the composite admixture.

Preferably, the ball milling conditions are: the ball-to-material ratio is 1:(1.5-2), and the rotation speed is 100-140 rpm.

Preferably, in the tuff, the content of SiO ₂ is greater than 65 wt%, the content of Al ₂ O ₃ is greater than 15 wt%, and the content of Fe ₂ O ₃ is greater than 2.5 wt%.

Preferably, the mass ratio of the tuff ore, melamine and active activator is 100: (1-2): (3-5): (0.2-0.5).

Preferably, the activity activating agent includes at least one of dihydrate gypsum, alunite or quicklime.

Preferably, the ultrafine powder is prepared by mixing and grinding fly ash, slag powder and grinding aid in a mass ratio of (40-50): (45-55): (0.1-0.5).

Preferably, the grinding aid is obtained by mixing triethanolamine, diethanol monoisopropanolamine, sodium dodecyl sulfonate and water in a weight ratio of 20:19:6:55. Triethanolamine has grinding aid and strengthening effect. Sodium dodecyl sulfonate acts as a surfactant to disperse, emulsify and solubilize, which can make triethanolamine and diethanol monoisopropanolamine better dispersed in water. ; Mixing triethanolamine, diethanol monoisopropanolamine and sodium dodecyl sulfonate can achieve better grinding aid effect.

Preferably, the specific surface area of the ultrafine powder is 600-700 m ² /kg.

Preferably, the fineness of the fly ash is less than 30%, the total mass fraction of SiO ₂ , Al ₂ O ₃ and Fe ₂ O ₃ is greater than 70%, and the 28d activity index is greater than 70%.

Another object of the present invention is to provide a method for preparing the concrete composite admixture. The steps are as follows: mix tuff powder and ultrafine powder according to the mass ratio, and stir evenly to obtain the concrete composite admixture.

Compared with the prior art, the benefits of the present invention are:

(1) In the present invention, tuff is mixed and ground with melamine and active activator. On the one hand, melamine can improve the grinding efficiency, and on the other hand, it can have a water-reducing effect, thereby improving the fluidity ratio of the composite admixture; at the same time, Active activators are added during grinding, and under the combined action of mechanical chemical action and chemical excitation, the activity index of the composite admixture is increased to ensure the strength of concrete at all ages.

(2) The present invention adds sodium hexametaphosphate during the tuff grinding process. Sodium hexametaphosphate has good dispersibility and can disperse the tuff powder to avoid the agglomeration effect of the tuff powder. On the one hand, it can improve the grinding efficiency. , on the other hand, it can also improve the activity index of the composite admixture.

(3) Triethanolamine has a grinding aid and strengthening effect. Sodium dodecyl sulfonate serves as a surfactant and plays the role of dispersion, emulsification and solubilization. It can disperse triethanolamine and diethanol monoisopropanolamine in water. The effect is better; mixing triethanolamine, diethanol monoisopropanolamine and sodium dodecyl sulfonate can achieve better grinding aid effect.

Description of the drawings

Figure 1 shows the SEM image of a single tuff ore after grinding for 1 hour;

Figure 2 shows the SEM image of a single tuff ore after grinding for 2 hours.

Detailed ways

The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

In the following examples and comparative examples, the chemical composition of tuff is as follows: the content of SiO ₂ is 68.71wt%, the content of Al ₂ O ₃ is 15.16wt%, the content of Fe ₂ O ₃ is 2.79wt%, and the content of CaO is 2.23 wt%, the content of MgO is 1.34wt%, the content of _SO3 is 0.2wt%, and the loss on ignition is 3.2%. The fineness of fly ash is less than 30%, the total mass fraction of SiO ₂ , Al ₂ O ₃ and Fe ₂ O ₃ is greater than 70%, and the 28d activity index is greater than 70%. The slag powder is S95 slag powder.

Example 1

This embodiment provides a method for preparing a concrete composite admixture containing tuff powder, which includes the following steps:

S1. Mix tuff ore, sodium hexametaphosphate, melamine and dihydrate gypsum in a mass ratio of 100:1.5:4:0.3. Then it was transferred to a ball mill and milled for 1 hour at a ball-to-material ratio of 1:1.8 and a rotation speed of 120 rpm to obtain tuff powder; the fineness of the obtained tuff was 9.25%.

S2. Put the fly ash, slag powder and grinding aid into the grinding equipment according to the mass ratio of 45:55:0.3 for mixing and grinding to obtain ultrafine powder with a specific surface area greater than 600m ² /kg; the grinding aid is composed of Triethanolamine, diethanol monoisopropanolamine, sodium dodecyl sulfonate and water are mixed according to the weight ratio of 20:19:6:55;

S3. Mix 60wt% of the tuff powder obtained in step S1 and 40wt% of the ultrafine powder obtained in step S2 evenly to obtain a concrete composite admixture.

In this embodiment, tuff powder and ultrafine powder are first prepared in steps, and then the two are mixed, and sodium hexametaphosphate, melamine and dihydrate gypsum are added during the grinding process of tuff ore, and then the fly ash and slag are grinded. Adding grinding aids during the grinding process can improve the grinding efficiency, reduce the energy consumption of the grinding process, and obtain a composite admixture with high activity index and high fluidity ratio.

Example 2

S1. Mix tuff ore, sodium hexametaphosphate, melamine and dihydrate gypsum in a mass ratio of 100:1:5:0.5, then transfer to a ball mill, and ball mill for 1 hour at a ball-to-material ratio of 1:1 and a rotation speed of 140 rpm. , to obtain tuff powder; the fineness of the obtained tuff is 11.23%.

S2. Put the fly ash, slag powder and grinding aid into the grinding equipment according to the mass ratio of 50:50:0.5 for mixing and grinding to obtain ultra-fine powder with a specific surface area greater than 600m ² /kg; the grinding aid is composed of Triethanolamine, diethanol monoisopropanolamine, sodium dodecyl sulfonate and water are mixed according to the weight ratio of 20:19:6:55;

S3. Mix 50wt% of the tuff powder obtained in step S1 and 50wt% of the ultrafine powder obtained in step S2 evenly to obtain a concrete composite admixture.

Example 3

S1. Mix tuff ore, sodium hexametaphosphate, melamine and dihydrate gypsum at a mass ratio of 100:2:3:0.2, then transfer to a ball mill, and ball mill for 1 hour at a ball-to-material ratio of 1:2 and a rotation speed of 100 rpm. , to obtain tuff powder; the fineness of the obtained tuff is 12.81%.

S2. Put the fly ash, slag powder and grinding aid into the grinding equipment according to the mass ratio of 40:55:0.1 for mixing and grinding to obtain ultra-fine powder with a specific surface area greater than 600m ² /kg; the grinding aid is composed of Triethanolamine, diethanol monoisopropanolamine, sodium dodecyl sulfonate and water are mixed according to the weight ratio of 20:19:6:55;

S3. Stir 70wt% of the tuff powder obtained in step S1 and 30wt% of the ultrafine powder obtained in step S2 evenly to obtain to concrete composite admixtures.

Example 4

Example 4 is basically the same as Example 1, except that in step S1, the ball milling time is 2 hours. The resulting tuff had a fineness of 8.05%.

Comparative example 1

This comparative example is basically the same as Example 1, except that in step S1, the ball milling time is 0.5h. The fineness of the resulting tuff was 22.20%.

Comparative example 2

The preparation method of this comparative example is basically the same as that of Example 1, except that step S1 is as follows:

S1. Mix tuff ore, sodium hexametaphosphate and dihydrate gypsum at a mass ratio of 104:1.5:0.3, then transfer to a ball mill, and grind for 1 hour at a ball-to-material ratio of 1:1.8 and a rotation speed of 120 rpm to obtain tuff powder. ;

Steps S2 and S3 are the same as Example 1, that is, compared with Example 1, the composite admixture of this comparative example lacks melamine.

Comparative example 3

S1. Mix tuff ore, melamine and dihydrate gypsum at a mass ratio of 101.5:4:0.3, then transfer to a ball mill, and grind for 1 hour at a ball-to-material ratio of 1:1.8 and a rotation speed of 120 rpm to obtain tuff powder;

Steps S2 and S3 are the same as Example 1, that is, compared with Example 1, the composite admixture of this comparative example lacks sodium hexametaphosphate.

Comparative example 4

The preparation method of this comparative example is basically the same as that of Example 1, except that step S2 is as follows:

S2. Put the fly ash, slag powder and grinding aid into the grinding equipment according to the mass ratio of 45:55:0.3 for mixing and grinding to obtain ultrafine powder with a specific surface area greater than 600m ² /kg; the grinding aid is composed of Triethanolamine, diethanol monoisopropanolamine and water are mixed according to the weight ratio of 20:19:61;

Steps S1 and S3 are the same as Example 1, that is, compared with Example 1, the grinding aid of this comparative example lacks sodium dodecyl sulfonate.

Test example

In accordance with the relevant provisions of JG/T315-2011 "Natural Pozzolanic Materials for Cement Mortar and Concrete", the fluidity ratio and activity index of the composite admixtures of the Examples and Comparative Examples were tested. Huaxin P·O 42.5 cement and ISO standard sand were used to form mortar specimens with dimensions of 40mm×40mm×160mm. The water-cement ratio of the mortar was controlled to be 0.5, and the dosage of the composite admixture was 30%, the mass ratio of cementitious material to standard sand is 1:3. The specimens were formed in an environment of 20°C and cured with the mold for 24 hours, and then the mold was removed and moved into a standard curing room. After curing to each age, the fluidity ratio and activity index were tested. The test results are shown in Table 1.

Table 1 Mobility ratio and activity index

It can be seen from the data in Table 1 that compared with Comparative Examples 1 to 4, the composite admixtures of Examples 1 to 4 of the present invention have high fluidity ratio and activity index; the grinding time of the tuff ore in Comparative Example 1 is too long. Short, resulting in an increase in the fineness of the tuff powder and a decrease in the activity index of the composite admixture. Comparative Example 2 lacks melamine. On the one hand, the grinding efficiency of the tuff ore is reduced and the activity index is reduced. On the other hand, due to the lack of water reducing effect, its fluidity ratio is reduced. Comparative Example 3 lacks sodium hexametaphosphate, the dispersibility of tuff powder is reduced, and the activity index of the composite admixture is reduced. The grinding aid of Comparative Example 4 lacks sodium dodecyl sulfonate, resulting in a weakened grinding aid effect, and the grinding time becomes longer while ensuring that the specific surface area of the ultrafine powder meets the requirements.

Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art will understand that various changes, modifications, and substitutions can be made to these embodiments without departing from the principles and spirit of the invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims

A concrete composite admixture containing tuff powder, which is characterized in that it includes the following mass percentages of each component: 50-70% tuff powder, 30-50% ultrafine powder;

The preparation method of the tuff powder is as follows: mix the tuff ore with sodium hexametaphosphate, melamine, and active activator, and then perform ball milling for 1 to 2 hours to obtain the tuff powder.
A concrete composite admixture containing tuff powder according to claim 1, characterized in that the ball milling conditions are: the ball-to-material ratio is 1: (1.5-2), and the rotation speed is 100-140 rpm.
A concrete composite admixture containing tuff powder according to claim 1, characterized in that, in the tuff, the content of SiO2 is greater than 65wt%, the content of Al2O3 is greater than 15wt%, and the content of Fe2O3 The content is greater than 2.5wt%.
A concrete composite admixture containing tuff powder according to claim 1, characterized in that the mass ratio of the tuff mineral, sodium hexametaphosphate, melamine and active activator is 100: (1-2): (3～5):(0.2～0.5).
A concrete composite admixture containing tuff powder according to claim 1, characterized in that the active activator includes at least one of dihydrate gypsum, alunite or quicklime.
A kind of concrete composite admixture containing tuff powder according to claim 1, characterized in that the ultrafine powder is composed of fly ash, slag powder and grinding aid according to the mass ratio (40-50): ( 45～55): (0.1～0.5) prepared by mixing and grinding.
A kind of concrete composite admixture containing tuff powder according to claim 6, characterized in that the grinding aid is composed of triethanolamine, diethanol monoisopropanolamine, sodium dodecyl sulfonate and water according to the following formula: Obtained by mixing with a weight ratio of 20:19:6:55.
A concrete composite admixture containing tuff powder according to claim 6, characterized in that the specific surface area of the ultrafine powder is 600-700 m 2 /kg.
A concrete composite admixture containing tuff powder according to claim 6, characterized in that the fineness of the fly ash is less than 30%, and the total mass fraction of SiO 2 , Al 2 O 3 and Fe 2 O 3 Greater than 70%, 28d activity index greater than 70%.
The preparation method of concrete composite admixture according to any one of claims 1 to 9, the steps are as follows: mix tuff powder and ultrafine powder according to the mass ratio, stir evenly to obtain the concrete composite admixture.