CN115215592A

CN115215592A - Refractory concrete and preparation method thereof

Info

Publication number: CN115215592A
Application number: CN202210748777.0A
Authority: CN
Inventors: 邝俊燊; 邝文辉; 张大康; 张玉露; 梁洪滔
Original assignee: Guangdong Zhidao Advanced Civil Engineering Materials Technology Research Co ltd
Current assignee: Guangdong Zhidao Advanced Civil Engineering Materials Technology Research Co ltd
Priority date: 2022-06-29
Filing date: 2022-06-29
Publication date: 2022-10-21
Anticipated expiration: 2042-06-29
Also published as: CN115215592B

Abstract

The invention discloses refractory concrete and a preparation method thereof, and relates to the technical field of concrete. The refractory concrete comprises the following components in parts by weight: 140-180 parts of modified secondary aluminum ash, 80-130 parts of a cementing material, 180-250 parts of an alkali activator, 1600-2000 parts of a refractory aggregate and 6-10 parts of an auxiliary material; the preparation method of the modified secondary aluminum ash and the alkali activator comprises the following steps: (1) Mixing the secondary aluminum ash and water, and reacting at 80-90 ℃ to obtain a reaction solution; (2) Adjusting the pH value of the reaction solution to 12.5-14, and carrying out solid-liquid separation to obtain a liquid phase intermediate and a solid phase intermediate; (3) Adding nano silicon dioxide into the liquid-phase intermediate, reacting to obtain an alkali activator, and drying the solid-phase intermediate to obtain the modified secondary aluminum ash. By implementing the invention, the production cost of the refractory concrete can be reduced, and the resource utilization of the secondary aluminum ash can be realized.

Description

Refractory concrete and preparation method thereof

Technical Field

The invention relates to the technical field of concrete, in particular to refractory concrete and a preparation method thereof.

Background

The refractory concrete material is widely applied to the fields of chemical industry, metallurgy, building materials and the like, and the application amount is extremely large. However, due to the extremely high requirement of the fire (thermal) resistance, the problems of special raw materials, high cost, complex preparation process and the like exist. On the other hand, the aluminum ash is used as solid waste generated in the production process of aluminum products such as electrolytic aluminum, blast furnace aluminum production and the like, and is an important factor for restricting the development of aluminum product enterprises in China gradually due to the problems of difficult safe disposal, low application value, environmental pollution caused by improper disposal and the like.

Disclosure of Invention

The invention aims to provide a refractory concrete which can fully utilize secondary aluminum ash and has low cost. And has better mechanical property and durability.

The technical problem to be solved by the invention is to provide a preparation method of the refractory concrete.

In order to solve the technical problems, the invention provides a refractory concrete which comprises the following components in parts by weight:

140-180 parts of modified secondary aluminum ash, 80-130 parts of cementing material, 180-250 parts of alkali activator, 1600-2000 parts of refractory aggregate and 6-10 parts of auxiliary material;

the preparation method of the modified secondary aluminum ash and alkali excitant comprises the following steps:

(1) Mixing the secondary aluminum ash and water, and reacting at 80-90 ℃ to obtain a reaction solution;

(2) Adjusting the pH value of the reaction solution to 12.5-14, and carrying out solid-liquid separation to obtain a liquid phase intermediate and a solid phase intermediate;

(3) Adding nano silicon dioxide into the liquid-phase intermediate, reacting to obtain an alkali activator, and drying the solid-phase intermediate to obtain the modified secondary aluminum ash.

As an improvement of the technical scheme, in the step (1), the secondary aluminum ash, water and the catalyst are mixed according to the weight ratio of 1: (4-6): (0.05-0.1), uniformly mixing, and reacting at 80-90 ℃ for 4-8h to obtain a reaction solution;

wherein the catalyst is one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate and sodium stannate.

As an improvement of the technical scheme, the catalyst is a mixture of sodium hydroxide and sodium stannate, and the weight ratio of the sodium hydroxide to the sodium stannate is (20-30): 1.

As an improvement of the technical scheme, in the step (3), nano silicon dioxide is added into the liquid-phase intermediate according to the proportion of 10-30g/L, and the mixture is stirred and reacted for 10-15min at the temperature of 60-90 ℃ to obtain the alkali activator.

As an improvement of the above technical scheme, in the step (2), a pH regulator is added into the reaction liquid to regulate the pH of the reaction liquid to 12.5-14;

the pH regulator is one or more of sodium hydroxide, potassium hydroxide and calcium hydroxide.

As an improvement of the technical scheme, the refractory aggregate is one or more of magnesite, dolomite, marble and olivine;

the cementing material is one or more of metakaolin, slag powder and fly ash;

the auxiliary materials are one or more of slump retaining agent, air entraining agent, defoaming agent, water reducing agent and sodium gluconate.

As an improvement of the technical scheme, the auxiliary material is a mixture of slump retaining agent mother liquor, an air entraining agent, a defoaming agent, sodium gluconate and water, and the mass ratio of the auxiliary material is (400-500): (400-500): (0.1-0.2): (0.1-0.2): (0.3-0.5).

As an improvement of the technical scheme, the refractory aggregate comprises refractory coarse aggregate and refractory fine aggregate;

the particle size of the refractory coarse aggregate is 0.075mm-4.75mm, and the particle size of the refractory fine aggregate is 4.755mm-37.5mm; .

As an improvement of the technical scheme, the content of Al element in the secondary aluminum ash is 40-55wt%, and the proportion of particles with the particle diameter larger than 80 mu m is less than or equal to 10wt%.

Correspondingly, the invention also discloses a preparation method of the refractory concrete, which comprises the following steps:

(1) Preparing modified secondary aluminum ash and an alkali activator;

(2) Mixing the modified secondary aluminum ash, the cementing material and the refractory aggregate to obtain a premix;

(3) And uniformly mixing the premix with an alkali activator and auxiliary materials to obtain a finished refractory concrete product.

The implementation of the invention has the following beneficial effects:

1. according to the invention, through a specific treatment process, aluminum nitride, aluminum carbide and the like which are easily decomposed when meeting water in the secondary aluminum ash are decomposed, and the secondary aluminum ash is converted into modified secondary aluminum ash and an alkali activator, and is completely utilized in the refractory concrete, so that the complete resource utilization of the secondary aluminum ash is realized, and no secondary waste residue is generated; and the production cost of the refractory concrete is also reduced.

2. In the modified secondary aluminum ash prepared by the specific treatment process, the chemical components are mainly alumina, so that the fire resistance of the fire-resistant concrete can be effectively improved. The main component of the alkali activator obtained by treatment is sodium silicate, which can effectively activate the activity of a gelling component in the refractory concrete and improve the mechanical property and durability of the refractory concrete. Meanwhile, the invention can adopt low-grade materials such as fly ash, slag and the like without introducing a cement cementing material, thereby further reducing the production cost of the refractory concrete.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to specific embodiments.

The invention discloses a refractory concrete which comprises the following components in parts by weight:

the preparation method of the modified secondary aluminum ash and the alkali activator comprises the following steps:

specifically, substances such as aluminum nitride, aluminum carbide, aluminum fluoride and simple substance aluminum which are easy to react when meeting water exist in the secondary aluminum ash, and if the secondary aluminum ash is directly introduced into the refractory concrete, the secondary aluminum ash is easy to react in the application process of adding water into the refractory concrete. Therefore, the secondary aluminum ash is treated firstly, and the harmful substances are converted firstly.

Preferably, in one embodiment of the present invention, the secondary aluminum ash, water and the catalyst are mixed according to a weight ratio of 1: (4-6): (0.05-0.1), uniformly mixing, and reacting at 80-90 ℃ for 4-8h to obtain a reaction solution; wherein the catalyst can be one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate and sodium stannate. Based on the reaction conditions, the reaction speed can be accelerated, and the full decomposition of harmful substances is ensured. Further preferably, the catalyst is a mixture of sodium hydroxide and sodium stannate, the weight ratio of the sodium hydroxide to the sodium stannate is 20-30, the sodium hydroxide is selected, the reaction speed can be accelerated, and the liquid phase product can be recycled in the later alkali activator preparation process. Sodium stannate is selected, so that the reaction speed is accelerated, the magnesium aluminate spinel phase in the secondary aluminum ash can be effectively reserved, and the fire resistance of the fire-resistant concrete is further improved.

Specifically, the content of the Al simple substance in the secondary aluminum ash is 40-55wt%. The secondary aluminum ash contains more Al simple substances, can form more alkali activators, and is convenient for realizing the complete resource utilization of the secondary aluminum ash. Furthermore, in one embodiment of the present invention, the proportion of the particles with the secondary aluminum ash of more than 70 μm is less than or equal to 10wt%, and more preferably, the D90 of the secondary aluminum ash is less than or equal to 70 μm, and the D50 is 40-50 μm, and the secondary aluminum ash is enriched in Al element and contains more magnesium aluminate spinel, which can effectively improve the fire resistance of the refractory concrete.

specifically, a pH regulator is added into the reaction solution to regulate the pH of the reaction solution to 12.5-14, and a liquid-phase intermediate and a solid-phase intermediate are obtained. The pH regulator may be one or more of sodium hydroxide, potassium hydroxide, and calcium hydroxide, but is not limited thereto. Sodium hydroxide is preferred.

Specifically, nano silicon dioxide is added into the liquid phase intermediate according to the proportion of 10-30g/L, and the mixture is stirred and reacted for 10-15min at the temperature of 60-90 ℃, so that the alkali activator is obtained. The alkali activator mainly comprises sodium silicate. Further, when the pH regulator is sodium hydroxide and the catalyst is sodium hydroxide or a mixture of sodium hydroxide and sodium stannate, the liquid-phase product obtained by the reaction of the liquid-phase intermediate and the nano-silica can also be recycled to the step (1).

Specifically, the drying temperature of the solid phase intermediate is 300-400 ℃, and the modified secondary aluminum ash with the main phase of aluminum oxide can be obtained after drying based on the process.

Based on the preparation method of the alkali activator and the modified secondary aluminum ash, the secondary aluminum ash is converted into the modified secondary aluminum ash and the alkali activator, and the modified secondary aluminum ash and the alkali activator are completely utilized in the refractory concrete, so that the complete resource utilization of the secondary aluminum ash is realized, and no secondary waste residue is generated; and the production cost of the refractory concrete is also reduced.

The amount of the modified secondary aluminum ash in the refractory concrete formulation is 140-180 parts, such as 142 parts, 145 parts, 150 parts, 154 parts, 160 parts, 166 parts, 170 parts or 175 parts, but not limited thereto. The alkali-activator is used in an amount of 180 to 250 parts, illustratively 188 parts, 195 parts, 200 parts, 210 parts, 225 parts, 230 parts, 245 parts, or 248 parts, but is not limited thereto.

Wherein, the cementing material can be one or more of cement, metakaolin, slag powder or fly ash, but is not limited to the above. The preferable slag powder or fly ash has excellent mechanical property and durability under the excitation of an alkali activator, belongs to industrial waste, and can reduce the production cost of the refractory concrete. Specifically, the gelling material is used in an amount of 80 to 130 parts, illustratively 80 parts, 85 parts, 90 parts, 95 parts, 100 parts, 105 parts, 115 parts, 120 parts, or 125 parts, but is not limited thereto.

The refractory aggregate can be one or more of magnesite, dolomite, marble and olivine, has high heat resistance and low thermal expansion coefficient, and is not easy to explode, crack or deform at high temperature. Further, in one embodiment of the present invention, the refractory aggregate includes a refractory coarse aggregate and a refractory fine aggregate; wherein the grain diameter range of the refractory coarse aggregate is 4.755mm-37.5mm, and the grain composition meets the requirement of GB/T14685-2001; the grain size range of the refractory fine aggregate is 0.075mm-4.75mm, and the gradation meets the requirement of the sand (machine-made sand) in the GB/T14684-2022 second region. The dosage of the refractory aggregate is 1600-2000 parts, wherein the dosage of the refractory coarse aggregate is 900-1100 parts, and the dosage of the refractory fine aggregate is 700-900 parts, but not limited to the above.

The auxiliary materials include water reducing agents, defoaming agents and the like which are common in the field of concrete, but are not limited to the above. Preferably, in an embodiment of the present invention, the auxiliary material is a mixture of slump retaining agent mother liquor, an air entraining agent, an antifoaming agent, sodium gluconate and water, and the mass ratio of the auxiliary material is (400-500): (400-500): (0.1-0.2): (0.1-0.2): (0.3-0.5). Wherein, the slump retaining agent mother solution is an aqueous solution of polyacid type slump retaining agent, and the concentration of the slump retaining agent mother solution is 5-15wt%. The auxiliary materials can ensure that the refractory concrete has good early working performance.

The invention will be further illustrated by the following specific examples

Example 1 preparation of modified Secondary aluminum Ash, alkali activator

The embodiment provides a preparation method of modified secondary aluminum ash and alkali activator, which specifically comprises the following steps:

(1) Mixing the secondary aluminum ash and water, and reacting at 85 ℃ for 10 hours to obtain a reaction solution;

wherein, the content of Al element in the secondary aluminum ash is 57.43%, and the grain diameter is as follows: d50 was 45.3 μm and D90 was 78.65. Mu.m. The weight ratio of the secondary aluminum ash to the water is 1:5.

(2) Adjusting the pH value of the reaction solution to 13 by adopting NaOH, and carrying out solid-liquid separation to obtain a liquid-phase intermediate and a solid-phase intermediate;

Specifically, nano silicon dioxide is added into the liquid phase intermediate according to the proportion of 22g/L, and the mixture is stirred and reacts for 15min at the temperature of 80 ℃, so that the alkali activator is obtained.

Specifically, the drying temperature of the solid phase intermediate is 350 ℃, and the drying time is 1h.

Example 2 preparation of modified Secondary aluminum Ash, alkali activator

The embodiment provides a preparation method of modified secondary aluminum ash and an alkali activator, which specifically comprises the following steps:

(1) Mixing the secondary aluminum ash, water and a catalyst, and reacting at 85 ℃ for 5 hours to obtain a reaction solution;

wherein, the content of Al element in the secondary aluminum ash is 57.43%, and the grain diameter is as follows: d50 was 45.3 μm and D90 was 78.65. Mu.m.

The weight ratio of the secondary aluminum ash, water and the catalyst is 1:5:0.07. the catalyst is sodium hydroxide.

Specifically, the drying temperature of the solid-phase intermediate is 350 ℃, and the drying time is 1h.

Example 3 preparation of modified Secondary aluminum Ash, alkali activator

wherein, the content of Al element in the secondary aluminum ash is 57.43%, the grain diameter: d50 was 45.3 μm and D90 was 78.65. Mu.m.

The weight ratio of the secondary aluminum ash, water and the catalyst is 1:5:0.07. the catalyst is sodium hydroxide and sodium stannate, and the weight ratio of the sodium hydroxide to the sodium stannate is 25.

Example 4 preparation of modified Secondary aluminum Ash, alkali activator

wherein, the content of Al element in the secondary aluminum ash is 45.33%, and the grain diameter is as follows: d50 is 42.8 μm, D90 is 65.55 μm.

EXAMPLE 5 fire-resistant concrete

The embodiment provides a refractory concrete, which comprises the following formula:

150 parts of modified secondary aluminum ash, 100 parts of cementing material, 220 parts of alkali activator, 1800 parts of refractory aggregate and 8 parts of auxiliary material;

wherein the cementing material is fly ash, the refractory aggregate is magnesite, and the magnesite comprises 1000 parts of coarse aggregate with the grain diameter of 4.75-37.5 mm and 800 parts of fine aggregate with the grain diameter of 0.3-4.75 mm. The auxiliary material is sodium gluconate.

Wherein the modified secondary aluminum ash and the alkali activator are the products prepared in example 1.

In this embodiment, the preparation method of the refractory concrete comprises:

(1) Preparing modified secondary aluminum ash and an alkali activator;

EXAMPLE 6 fire-resistant concrete

This example provides a refractory concrete which is different from example 5 in that modified secondary aluminum ash and an alkali-activating agent are the products obtained in example 2, and the rest is the same as example 5.

Example 7 refractory concrete

This example provides a refractory concrete which is different from example 5 in that modified secondary aluminum ash and an alkali-activating agent are the same as those prepared in example 3, and the rest is the same as example 5.

EXAMPLE 8 fire-resistant concrete

This example provides a refractory concrete, which is different from example 5 in that the modified secondary aluminum ash and the alkali-activator are the same as those prepared in example 4, and the rest is the same as example 5.

Example 9 fire-resistant concrete

The embodiment provides a refractory concrete, which is different from embodiment 8 in that the auxiliary materials are a mixture of slump retaining agent mother liquor, an air entraining agent, a defoaming agent, sodium gluconate and water, and the mass ratio of the auxiliary materials is 430:420:0.15:0.12:0.4. wherein, the slump retaining agent mother liquor is an aqueous solution of polycarboxylic acid slump retaining agent, and the concentration of the slump retaining agent mother liquor is 10.8wt%.

The refractory concretes obtained in examples 5 to 9 were tested by the following specific test methods:

(1) Compressive strength (3 d, 28 d): the determination is carried out according to GB/T50081-2019 Standard of mechanical property test method of common concrete.

(2) Residual strength after firing: the concrete test block is maintained for 28 days in a standard way, after surface moisture is wiped off, the concrete test block is put into a high-temperature furnace to be calcined (the calcining temperature procedure is that the temperature is increased from 30 ℃ at room temperature to 850 ℃ within 2.5 hours, the constant-temperature calcining is carried out at 850 ℃ for 2.5 hours, and the calcining temperature is naturally cooled to the room temperature along with the furnace), and the compressive strength after the calcining is measured according to GB/T50081-2019 Standard of testing methods of mechanical properties of common concrete.

(3) Fire resistance: the calculation method is as follows: post-calcination strength/pre-calcination strength (28 d).

The specific measurement results are as follows:

performance index	Example 5	Example 6	Example 7	Example 8	Example 9
						3d Strength (MPa)	16.9	17.8	17.8	16.5	18.3
28d Strength (MPa)	37.5	39.6	40.3	39.5	41.2
						Residual Strength after firing (MPa)	26.4	29	30.4	31.3	35.2
Fire resistance	0.70	0.73	0.75	0.79	0.85

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.

Claims

1. The refractory concrete is characterized by comprising the following components in parts by weight:

2. The refractory concrete according to claim 1, wherein in the step (1), the secondary aluminum ash, water and the catalyst are mixed in a weight ratio of 1: (4-6): (0.05-0.1), uniformly mixing, and reacting at 80-90 ℃ for 4-8h to obtain a reaction solution;

3. The refractory concrete according to claim 2, wherein the catalyst is a mixture of sodium hydroxide and sodium stannate, and the weight ratio of sodium hydroxide to sodium stannate is (20-30): 1.

4. The refractory concrete according to claim 1, wherein in the step (3), nanosilicon dioxide is added to the liquid-phase intermediate in a proportion of 10-30g/L, and the mixture is stirred and reacted at 60-90 ℃ for 10-15min to obtain the alkali-activator.

5. The refractory concrete according to claim 1, wherein in the step (2), a pH adjusting agent is added to the reaction liquid to adjust the pH of the reaction liquid to 12.5 to 14;

6. The refractory concrete according to claim 1, wherein the refractory aggregate is one or more of magnesite, dolomite, marble and olivine;

the cementing material is one or more of metakaolin, slag powder and fly ash;

7. The refractory concrete of claim 1, wherein the auxiliary materials are a mixture of slump retaining agent mother liquor, an air entraining agent, an antifoaming agent, sodium gluconate and water, and the mass ratio of the auxiliary materials is (400-500): (400-500): (0.1-0.2): (0.1-0.2): (0.3-0.5).

8. The refractory concrete of claim 1, wherein the refractory aggregate comprises a refractory coarse aggregate and a refractory fine aggregate;

the particle size of the refractory coarse aggregate is 0.075mm-4.75mm;

the particle size of the refractory fine aggregate is 4.755mm-37.5mm.

9. The refractory concrete according to claim 1, wherein the content of Al element in the secondary aluminum ash is 40 to 55wt%, and the proportion of particles having a particle size of more than 70 μm is 10wt% or less.

10. A method of preparing a refractory concrete according to any one of claims 1 to 9, comprising:

(1) Preparing modified secondary aluminum ash and an alkali activator;