Special modified cementing material for carbon negative red mud-based soft soil and preparation method of special modified cementing material

Abstract

The invention discloses a special modified cementing material for carbon negative red mud-based soft soil and a preparation method thereof, and relates to the technical field of cementing materials, the modified cementing material comprises the following raw materials: red mud, modified cement, slag powder, desulfurized gypsum powder, fly ash, nano-silica, a composite modifier, cellulose, a water reducer, an activator and water; according to the preparation method, the red mud, the modified cement and the slag powder are taken as main materials, the desulfurized gypsum powder, the fly ash, the nano silicon dioxide and the cellulose are taken as auxiliary materials, and the additives including the composite modifier, the water reducing agent and the exciting agent are taken as auxiliary materials, so that the special modified cementing material for the carbon-negative red mud-based soft soil is prepared, industrial wastes can be effectively utilized, and the cost is reduced. The preparation method is simple, the production cost is reduced, the economic benefit is improved, the prepared modified gel material has good fluidity, flexibility, compressive strength and breaking strength, the comprehensive performance is effectively improved, and the modified gel material can be widely applied to the field of buildings.

Description

Technical Field

[0001] The invention relates to the technical field of cementitious materials, and in particular to a modified cementitious material specially used for carbon-negative red mud-based soft soil and a preparation method thereof. Background Art

[0002] Carbon-negative red mud-based soft soil refers to a carbon-negative building material that is prepared through a specific process using red mud as the main raw material. It is a new type of building material with environmental protection and energy-saving properties. The characteristic of this material is that it can achieve negative carbon emissions during its production and use, that is, the amount of carbon dioxide absorbed is greater than the amount of carbon dioxide emitted during its life cycle. It has broad application prospects in the fields of construction, infrastructure construction, and environmental protection.

[0003] Cementitious materials refer to materials that can bond granular or block materials into a whole through a series of physical and chemical reactions in construction projects. They play a vital role in modern construction projects. They are not only related to the safety and durability of the structure, but also affect the beauty and economic benefits of the building. With the development of science and technology, the types and properties of cementitious materials are also constantly improving. For example, new materials such as high-performance concrete and polymer-modified cement have emerged. These materials are playing an increasingly important role in improving the quality of construction projects, extending service life, and saving resources.

[0004] Most of the existing cementitious materials have fixed materials, single ingredients, high raw material costs, and cannot bring good economic benefits. The prepared gel materials do not have good flexibility, compressive strength and flexural strength, which limits the scope of application. The flowability needs to be improved, resulting in poor filling properties and cannot bring convenience to construction. Therefore, the present invention proposes a modified cementitious material specially used for carbon-negative red mud-based soft soil and a preparation method thereof to solve the problems existing in the prior art. Summary of the invention

[0005] In view of the above problems, the purpose of the present invention is to propose a modified cementitious material specially used for carbon-negative red mud-based soft soil and a preparation method thereof, so as to solve the problems that the raw material costs of existing cementitious materials are high and cannot bring good economic benefits, and the prepared gel material does not have good flexibility, compressive strength and flexural strength, and the flowability needs to be improved, resulting in poor filling properties.

[0006] In order to achieve the purpose of the present invention, the present invention is implemented through the following technical scheme: a modified cementitious material specially used for carbon-negative red mud-based soft soil, comprising the following raw materials in parts by weight: 20 to 25 parts of red mud, 10 to 13 parts of modified cement, 16 to 20 parts of slag powder, 5 to 10 parts of desulfurized gypsum powder, 17 to 22 parts of fly ash, 4 to 7 parts of nano silicon dioxide, 5 to 10 parts of composite modifier, 0.5 to 1 part of cellulose, 1 to 3 parts of water reducer, 2 to 4 parts of activator and 20 to 30 parts of water.

[0007] A further improvement is that the red mud is selected from one of Bayer process red mud and sintering process red mud. The Bayer process red mud is red mud produced by Bayer process aluminum smelting, and the sintering process red mud is red mud produced by sintering process aluminum smelting.

[0008] A further improvement is that the specific preparation method of the modified cement is: first, cement clinker, mica powder, limestone powder and siliceous stone powder are mixed in a mass ratio of 10:1:1:1 and sent into a ball mill for fine grinding to obtain a mixed powder, then a cement modifier is added to the ball mill and continued to be finely ground, and after mixing evenly, the mixture is dried to obtain a modified cement powder.

[0009] A further improvement is that the mass ratio of the mixed powder to the cement modifier is 10:1, and the cement modifier is prepared by mixing polypropylene fiber and zeolite powder in a mass ratio of 1:1.

[0010] A further improvement is that the slag powder is composed of calcium oxide, calcium sulfide, iron oxide, calcium silicate and calcium aluminate, and the mass ratio of calcium oxide, calcium sulfide, iron oxide, calcium silicate and calcium aluminate is 15:5:15:10:2.

[0011] A further improvement is that the composite modifier is formed by mixing a cross-linking agent, a plasticizer, an antioxidant and a surfactant in a mass ratio of 3:2:1:1, the cross-linking agent is glutaraldehyde, the plasticizer is selected from one of glycerol or polyethylene glycol, the antioxidant is selected from one of vitamin E or butylated hydroxyanisole, and the surfactant is selected from one of Tween or sodium dodecyl sulfate.

[0012] A further improvement is that the cellulose is selected from one of cellulose nanocrystals or cellulose nanofibers, the water reducer is selected from one of polyvinyl alcohol or polyacrylamide, and the activator is selected from one of calcium chloride or sodium sulfate.

[0013] A method for preparing a modified cementitious material specially used for carbon-negative red mud-based soft soil comprises the following steps:

[0014] Step 1: weigh 20-25 parts of red mud, 10-13 parts of modified cement, 16-20 parts of slag powder, 5-10 parts of desulfurized gypsum powder, 17-22 parts of fly ash, 4-7 parts of nano silicon dioxide, 5-10 parts of composite modifier, 0.5-1 part of cellulose, 1-3 parts of water reducer, 2-4 parts of activator and 20-30 parts of water for later use;

[0015] Step 2: firstly pulverize the red mud for pretreatment, then use a tablet press to press the red mud powder into flakes, then heat and calcine the obtained red mud flakes to 700°C to 900°C at a heating rate of 5 to 8°C / s, and then keep the temperature after calcination, keep the temperature for 40 to 60 minutes, then naturally cool to room temperature, and then use a grinder to grind into powder to obtain modified red mud powder;

[0016] Step 3: first, mix the modified red mud powder obtained in step 2 with the modified cement, slag powder and water weighed in step 1, then add the composite modifier, cellulose, water reducer and activator to the mixture in sequence and continue to mix evenly, then add desulfurized gypsum powder, fly ash and nano-silicon dioxide to the mixture, stir evenly and let it stand for 1 to 2 hours to obtain a modified cementitious material specially used for carbon-negative red mud-based soft soil.

[0017] A further improvement is that in step 2, the specific steps of crushing the red mud for pretreatment are: first, the impurities in the red mud are screened out, then the red mud is washed, then the washed red mud is dried, and finally the dried red mud is ground into powder using a grinder to obtain red mud powder.

[0018] The beneficial effects of the present invention are as follows: the present invention uses red mud, modified cement and slag powder as main materials, and uses desulfurized gypsum powder, fly ash, nano-silicon dioxide and cellulose as auxiliary materials, and is supplemented with additives including composite modifiers, water reducers and activators, thereby preparing a modified gelling material specially used for carbon-negative red mud-based soft soil, which can not only effectively utilize industrial waste, reduce production costs and improve economic benefits, but also the prepared modified gel material has good fluidity, flexibility, compressive strength and flexural strength, and the comprehensive performance is effectively improved, and can be widely used in the field of construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1The present invention is a schematic flow chart of a method for preparing a modified cementitious material specially used for carbon-negative red mud-based soft soil. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Embodiment 1

[0023] The present embodiment provides a modified cementitious material for carbon-negative red mud-based soft soil, comprising the following raw materials in parts by weight: 20 parts of red mud, 10 parts of modified cement, 16 parts of slag powder, 5 parts of desulfurized gypsum powder, 17 parts of fly ash, 4 parts of nano-silicon dioxide, 5 parts of composite modifier, 0.5 parts of cellulose, 1 part of water reducer, 2 parts of activator and 20 parts of water, wherein the desulfurized gypsum and fly ash are both industrial wastes from coal-fired power plants, and using them for cementitious materials can effectively utilize this industrial waste, reduce production costs, improve economic benefits, and can improve the compressive strength and flexural strength of the gel material to a certain extent, and the nano-silicon dioxide has an extremely high specific surface area, which helps to improve the adsorption capacity and chemical reaction activity of the gel material;

[0024] The red mud used in this embodiment is Bayer red mud, which is red mud produced by Bayer aluminum smelting. Using red mud as the main material to prepare the gel material can not only improve the durability and mechanical properties of the gel material such as compressive strength, but also achieve resource recycling, reduce solid waste accumulation, and save energy and protect the environment.

[0025] The modified cement used in the present embodiment is prepared by using cement clinker, mica powder, limestone powder and siliceous stone powder as raw materials and modified by a physical method. The specific preparation method is: first, cement clinker, mica powder, limestone powder and siliceous stone powder are mixed in a mass ratio of 10:1:1:1 and sent to a ball mill for fine grinding to obtain a mixed powder, then a cement modifier is added to the ball mill in a mass ratio of 10:1 to the mixed powder and the cement modifier, and the mixture is further finely ground. After uniform mixing, the mixture is dried to obtain a modified cement powder. By using the modified cement as the main material and preparing a gel material, it is helpful to improve the toughness and overall bearing capacity of the gel material, wherein the cement modifier is prepared by mixing polypropylene fiber and zeolite powder in a mass ratio of 1:1;

[0026] The slag powder used in this embodiment is industrial waste, which contains calcium oxide, calcium sulfide, iron oxide, calcium silicate and calcium aluminate in a mass ratio of 15:5:15:10:2. The slag powder is used as the main material to prepare the gel material, which can further improve the compressive strength and flexural strength of the gel material, and can realize the resource utilization of process waste and improve economic benefits.

[0027] The composite modifier used in this embodiment is a mixture of a cross-linking agent, a plasticizer, an antioxidant and a surfactant in a mass ratio of 3:2:1:1. The cross-linking agent is glutaraldehyde, which is used to improve the mechanical strength and thermal stability of the gel material. The plasticizer is glycerol, which is used to improve the flexibility and ductility of the gel material. The antioxidant is vitamin E, which is used to improve the antioxidant performance of the gel material. The surfactant is Tween, which is used to improve the performance of the gel material. The composite modifier is used to modify the gel material to improve the performance of the gel material.

[0028] The cellulose used in this embodiment is cellulose nanocrystals, which improve the mechanical strength of the gel magnetic material to a certain extent and adjust the rheological properties of the gel material. The water reducer is polyvinyl alcohol, which can improve the fluidity of the gel material and increase the strength and durability of the gel material. The activator is calcium chloride, which can promote the chemical reaction in the gel material.

[0029] See also Figure 1 This embodiment provides a method for preparing a modified cementitious material specially used for carbon-negative red mud-based soft soil, comprising the following steps:

[0030] Step 1: firstly, using a weighing device to weigh red mud, modified cement, slag powder, desulfurized gypsum powder, fly ash, nano silicon dioxide, composite modifier, cellulose, water reducer, activator and water according to the above raw material mass ratio, and store them separately for standby;

[0031] Step 2: first, remove the impurities in the red mud, then wash the red mud, then dry the washed red mud, and finally grind the dried red mud into powder using a grinder to obtain red mud powder, which is beneficial to subsequent processing. Then, a tablet press is used to press the red mud powder into thin sheets, and then the obtained red mud thin sheets are heated and calcined to 700°C at a heating rate of 5°C / s. After calcination, they are kept warm for 40 minutes and then naturally cooled to room temperature. Then, they are ground into powder using a grinder to obtain modified red mud powder. By modifying the red mud, the physical properties of the red mud, such as the particle size and pore structure, can be changed so that it can be fully blended with other raw materials, which is beneficial to subsequent processing;

[0032] Step three: first mix the modified red mud powder obtained in step two with the modified cement, slag powder and water weighed in step one, then add the composite modifier, cellulose, water reducer and activator to the mixture in sequence and continue to mix evenly, then add desulfurized gypsum powder, fly ash and nano-silica to the mixture, stir evenly and let it stand for 1 hour to achieve a modified cementitious material prepared based on the blending modification method, that is, a modified cementitious material specifically for carbon-negative red mud-based soft soil.

[0033] Embodiment 2

[0034] The present embodiment provides a modified cementitious material for carbon-negative red mud-based soft soil, comprising the following raw materials in parts by weight: 25 parts of red mud, 13 parts of modified cement, 20 parts of slag powder, 10 parts of desulfurized gypsum powder, 22 parts of fly ash, 7 parts of nano-silicon dioxide, 10 parts of composite modifier, 1 part of cellulose, 3 parts of water reducer, 4 parts of activator and 30 parts of water, wherein the desulfurized gypsum and fly ash are both industrial wastes from coal-fired power plants, and using them for cementitious materials can effectively utilize this industrial waste, reduce production costs, improve economic benefits, and can improve the compressive strength and flexural strength of the gel material to a certain extent, and the nano-silicon dioxide has an extremely high specific surface area, which helps to improve the adsorption capacity and chemical reaction activity of the gel material;

[0035] The red mud used in this embodiment is sintered red mud, which is red mud produced by aluminum smelting using the sintering method. Using red mud as the main material to prepare the gel material can not only improve the durability and mechanical properties of the gel material such as compressive strength, but also achieve resource recycling, reduce solid waste accumulation, and save energy and protect the environment;

[0036] The modified cement used in the present embodiment is prepared by using cement clinker, mica powder, limestone powder and siliceous stone powder as raw materials and modified by a physical method. The specific preparation method is: first, cement clinker, mica powder, limestone powder and siliceous stone powder are mixed in a mass ratio of 10:1:1:1 and sent to a ball mill for fine grinding to obtain a mixed powder, then a cement modifier is added to the ball mill in a mass ratio of 10:1 to the mixed powder and the cement modifier, and the mixture is further finely ground. After uniform mixing, the mixture is dried to obtain a modified cement powder. By using the modified cement as the main material and preparing a gel material, it is helpful to improve the toughness and overall bearing capacity of the gel material, wherein the cement modifier is prepared by mixing polypropylene fiber and zeolite powder in a mass ratio of 1:1;

[0037] The slag powder used in this embodiment is industrial waste, which contains calcium oxide, calcium sulfide, iron oxide, calcium silicate and calcium aluminate in a mass ratio of 15:5:15:10:2. The slag powder is used as the main material to prepare the gel material, which can further improve the compressive strength and flexural strength of the gel material, and can realize the resource utilization of process waste and improve economic benefits.

[0038] The composite modifier used in this embodiment is a mixture of a cross-linking agent, a plasticizer, an antioxidant and a surfactant in a mass ratio of 3:2:1:1. The cross-linking agent is glutaraldehyde, which improves the mechanical strength and thermal stability of the gel material. The plasticizer is polyethylene glycol, which is used to improve the flexibility and ductility of the gel material. The antioxidant is butylated hydroxyanisole, which is used to improve the antioxidant performance of the gel material. The surfactant is sodium dodecyl sulfate, which is used to improve the performance of the gel material. The composite modifier is used to modify the gel material to improve the performance of the gel material.

[0039] The cellulose used in this embodiment is cellulose nanofiber, which improves the mechanical strength of the gel magnetic material to a certain extent and adjusts the rheological properties of the gel material. The water reducer is polyacrylamide, which can improve the fluidity of the gel material and increase the strength and durability of the gel material. The stimulator is sodium sulfate, which can promote the chemical reaction in the gel material.

[0040] See also Figure 1 This embodiment provides a method for preparing a modified cementitious material specially used for carbon-negative red mud-based soft soil, comprising the following steps:

[0041] Step 1: firstly, using a weighing device to weigh red mud, modified cement, slag powder, desulfurized gypsum powder, fly ash, nano silicon dioxide, composite modifier, cellulose, water reducer, activator and water according to the above raw material mass ratio, and store them separately for standby;

[0042] Step 2: first, remove the impurities in the red mud, then wash the red mud, then dry the washed red mud, and finally grind the dried red mud into powder using a grinder to obtain red mud powder, which is beneficial to subsequent processing. Then, a tablet press is used to press the red mud powder into thin sheets, and then the obtained red mud thin sheets are heated and calcined to 900°C at a heating rate of 8°C / s. After calcination, they are kept warm for 60 minutes and then naturally cooled to room temperature. Then, they are ground into powder using a grinder to obtain modified red mud powder. By modifying the red mud, the physical properties of the red mud, such as the particle size and pore structure, can be changed so that it can be fully blended with other raw materials, which is beneficial to subsequent processing;

[0043] Step three: first mix the modified red mud powder obtained in step two with the modified cement, slag powder and water weighed in step one, then add the composite modifier, cellulose, water reducer and activator to the mixture in sequence and continue to mix evenly, then add desulfurized gypsum powder, fly ash and nano-silica to the mixture, stir evenly and let it stand for 2 hours to achieve a modified cementitious material based on the blending modification method, that is, a modified cementitious material specially used for carbon-negative red mud-based soft soil.

[0044] The carbon-negative red mud-based soft soil modified gelling material and cement-based aerogel thermal insulation and sound insulation material prepared in Example 1 and Example 2 of the present invention (purchased from Guangdong Huolun Building Materials Technology Development Co., Ltd.) were first tested for fluidity, and the fluidity test standard was referenced to the standard ASTM D2196. Then, each gel material was cast in a mold, and after curing for 28 days, the flexibility, compressive strength and flexural strength were tested respectively, wherein the flexibility test standard was referenced to the standard JC / T547-2005, and the compressive strength and flexural strength tests were referenced to the standard GB175-2007. The test results are shown in Table 1 below:

[0045] Table 1 Test results

[0046]

[0047] It can be seen from Table 1 above that the modified gel materials prepared in Example 1 and Example 2 of the present invention have better fluidity, flexibility, compressive strength and flexural strength than traditional gel materials.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A modified cementitious material specially used for carbon-negative red mud-based soft soil, characterized in that: The invention comprises the following raw materials in parts by weight: 20-25 parts of red mud, 10-13 parts of modified cement, 16-20 parts of slag powder, 5-10 parts of desulfurized gypsum powder, 17-22 parts of fly ash, 4-7 parts of nano silicon dioxide, 5-10 parts of composite modifier, 0.5-1 part of cellulose, 1-3 parts of water reducer, 2-4 parts of activator and 20-30 parts of water.

2. The modified cementitious material for carbon-negative red mud-based soft soil according to claim 1, characterized in that: The red mud is selected from one of Bayer process red mud and sintering process red mud. The Bayer process red mud is red mud produced by Bayer process aluminum smelting, and the sintering process red mud is red mud produced by sintering process aluminum smelting.

3. The modified cementitious material for carbon-negative red mud-based soft soil according to claim 1, characterized in that: The specific preparation method of the modified cement is: firstly, cement clinker, mica powder, limestone powder and siliceous stone powder are mixed in a mass ratio of 10:1:1:1 and sent into a ball mill for fine grinding to obtain a mixed powder, then cement modifier is added into the ball mill for further fine grinding, mixed evenly and then dried to obtain modified cement powder.

4. The modified cementitious material for carbon-negative red mud-based soft soil according to claim 3, characterized in that: The mass ratio of the mixed powder to the cement modifier is 10:1, and the cement modifier is prepared by mixing polypropylene fiber and zeolite powder in a mass ratio of 1:

1.

5. The modified cementitious material for carbon-negative red mud-based soft soil according to claim 1, characterized in that: The slag powder consists of calcium oxide, calcium sulfide, iron oxide, calcium silicate and calcium aluminate, and the mass ratio of the calcium oxide, calcium sulfide, iron oxide, calcium silicate and calcium aluminate is 15:5:15:10:

2.

6. The modified cementitious material for carbon-negative red mud-based soft soil according to claim 1, characterized in that: The composite modifier is prepared by mixing a crosslinking agent, a plasticizer, an antioxidant and a surfactant in a mass ratio of 3:2:1:1, wherein the crosslinking agent is glutaraldehyde, the plasticizer is selected from one of glycerol or polyethylene glycol, the antioxidant is selected from one of vitamin E or butylated hydroxyanisole, and the surfactant is selected from one of Tween or sodium dodecyl sulfate.

7. The modified cementitious material for carbon-negative red mud-based soft soil according to claim 1, characterized in that: The cellulose is selected from one of cellulose nanocrystals and cellulose nanofibers, the water reducer is selected from one of polyvinyl alcohol and polyacrylamide, and the activator is selected from one of calcium chloride and sodium sulfate.

8. A method for preparing a modified cementitious material specially used for carbon-negative red mud-based soft soil as claimed in claim 1, characterized in that: The following steps are involved: Step 1: weigh 20-25 parts of red mud, 10-13 parts of modified cement, 16-20 parts of slag powder, 5-10 parts of desulfurized gypsum powder, 17-22 parts of fly ash, 4-7 parts of nano silicon dioxide, 5-10 parts of composite modifier, 0.5-1 part of cellulose, 1-3 parts of water reducer, 2-4 parts of activator and 20-30 parts of water for later use; Step 2: firstly pulverize the red mud for pretreatment, then use a tablet press to press the red mud powder into flakes, then heat and calcine the obtained red mud flakes to 700°C to 900°C at a heating rate of 5 to 8°C / s, and then keep the temperature after calcination, keep the temperature for 40 to 60 minutes, then naturally cool to room temperature, and then use a grinder to grind into powder to obtain modified red mud powder; Step 3: first, mix the modified red mud powder obtained in step 2 with the modified cement, slag powder and water weighed in step 1, then add the composite modifier, cellulose, water reducer and activator to the mixture in sequence and continue to mix evenly, then add desulfurized gypsum powder, fly ash and nano-silicon dioxide to the mixture, stir evenly and let it stand for 1 to 2 hours to obtain a modified cementitious material specially used for carbon-negative red mud-based soft soil.

9. The method for preparing a modified cementitious material specially used for carbon-negative red mud-based soft soil according to claim 8, characterized in that: In the step 2, the specific steps of crushing the red mud for pretreatment are: firstly, the impurities in the red mud are screened out, then the red mud is washed, then the washed red mud is dried, and finally the dried red mud is ground into powder by a grinder to obtain red mud powder.

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