Preparation method of sulphoaluminate cement-carbide slurry autoclaved aerated concrete

Abstract

The invention discloses a preparation method of sulphoaluminate cement-calcium carbide slurry autoclaved aerated concrete, which comprises the following steps: (1) adding weighed fly ash, waste aerated concrete material, calcium carbide slurry, desulfurized gypsum and foam stabilizer into water, and mixing and stirring to obtain slurry A; (2) adding sulphoaluminate cement into the slurry A, and quickly stirring to obtain slurry B; (3) adding the aluminum powder paste into the slurry B, and quickly stirring to obtain slurry C; (4) pouring the slurry C into a mold, and standing in a hot chamber to obtain a green body; and (5) cutting the green body, and performing autoclaved curing to obtain the autoclaved aerated concrete. According to the invention, the fly ash-calcium carbide slurry system is enabled to be fast in setting and hardening and fast in early strength increase in a manner of adding the sulphoaluminate cement, an alkali activator does not need to be added additionally, the problem of poor primary curing strength after calcium carbide slurry replaces quick lime in an aerated concrete process is solved, and the calcium carbide slurry completely replaces the lime, so that the cost is reduced. The emission of carbon dioxide is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and particularly relates to a method for preparing sulphoaluminate cement-carbide mud autoclaved aerated concrete. Background Art

[0002] Calcium carbide mud, a solid waste from the polyvinyl chloride (PVC) manufacturing industry, produces a massive amount of waste each year, resulting in a stockpile of tens of millions of tons. Calcium carbide mud solutions are highly alkaline. Large accumulations of this waste not only alter the soil's acid-base balance and damage the soil quality, but also accumulate over time, accumulating numerous toxic and hazardous substances. These substances gradually seep into the groundwater during rainwater erosion, posing a serious threat to the health and living environment of surrounding residents. Currently, the utilization rate of calcium carbide mud is also very low, hindering the development of the PVC manufacturing industry. Therefore, its comprehensive resource utilization is urgent. China has abundant coal resources, and thermal power generation will continue. The discharge of solid wastes such as fly ash and calcium carbide mud is significant, placing significant pressure on the environment and land. Therefore, the comprehensive utilization and green treatment of solid wastes such as fly ash and calcium carbide mud are urgent. Using large amounts of coal-based solid waste to replace cement in the production of composite cementitious materials holds great practical significance. Research has shown that fly ash has potential activity, capable of generating cementitious materials under the influence of activators. When mixed with alkaline substances such as alkali and calcium carbide mud, fly ash undergoes hydration in an alkaline environment, generating hydrated gelling products that reduce the porosity of the composite cementitious material and make the structure denser. Components such as hydrated calcium silicate gel, hydrated calcium aluminate gel, and ettringite, which have structures and properties similar to cement paste, continuously enhance the strength of the composite cementitious material.

[0003] Because calcium carbide mud is primarily composed of calcium hydroxide, it can be used to replace lime in the production of aerated concrete, thereby reducing carbon dioxide emissions, achieving low-cost, green production, and addressing the environmental pollution caused by calcium carbide mud residue emissions. However, replacing quicklime with calcium carbide mud directly affects the gasification effect of aluminum powder and the initial curing strength of concrete blocks.

[0004] When using calcium carbide mud to produce aerated blocks, it basically partially replaces quicklime, or calcium carbide mud is calcined with quicklime to prepare aerated blocks. It can be seen that the shortcomings of using calcium carbide mud to completely replace quicklime to prepare autoclaved aerated concrete blocks mainly include the following: First, there is no hydration heat when calcium carbide mud dissolves in water, resulting in a low temperature of the aerated block slurry; second, the hydration rate of calcium carbide mud is slow, resulting in low alkalinity in the system, which is not conducive to stimulating the pozzolanic activity of fly ash; third, it is usually necessary to add an excessive amount of alkali activator, resulting in high alkali dissolution in the system; fourth, it is usually impossible to completely replace quicklime with calcium carbide mud to produce high-performance autoclaved aerated concrete. Therefore, studying a method for preparing autoclaved aerated concrete by completely replacing quicklime with calcium carbide mud is a technical problem that is currently in urgent need of solution. Summary of the Invention

[0005] In order to overcome the deficiencies in the prior art, the present invention aims to provide a method for preparing sulphoaluminate cement-carbide mud autoclaved aerated concrete. By adding sulphoaluminate cement, the fly ash-carbide mud system achieves rapid setting and hardening, and rapid early strength growth, without the need for the addition of an alkali activator. This method solves the problem of poor initial strength after carbide mud replaces quicklime in the aerated concrete process, and achieves complete replacement of lime with carbide mud, thereby reducing carbon dioxide emissions.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for preparing sulphoaluminate cement-carbide mud autoclaved aerated concrete, the preparation method comprising the following steps:

[0008] (1) Weigh fly ash, waste aerated concrete material, calcium carbide mud, desulfurized gypsum, sulfoaluminate cement, foam stabilizer, and aluminum paste according to mass percentage;

[0009] (2) adding the fly ash, waste aerated concrete material, calcium carbide mud, desulfurized gypsum and foam stabilizer weighed in step (1) into water, and mixing and stirring in a blender for 60 seconds to obtain slurry A;

[0010] (3) adding the sulphoaluminate cement weighed in step (1) to the slurry A obtained in step (2), and rapidly and thoroughly mixing and stirring for 60 seconds to obtain slurry B;

[0011] (4) adding the aluminum powder paste weighed in step (1) to slurry B obtained in step (3) and rapidly stirring for 40 seconds to obtain slurry C;

[0012] (5) pouring the slurry C obtained in step (4) into a mold, placing it in a hot chamber and allowing it to stand for a while, and forming a green body that can be processed as it expands, thickens, and hardens with gas;

[0013] (6) Cutting and processing the green body obtained in step (5), and autoclaving and curing to prepare sulphoaluminate cement-carbide mud autoclaved aerated concrete.

[0014] Furthermore, the percentages of the raw materials in step (1) are: fly ash 75-79%, waste aerated concrete material 3.2-5%, calcium carbide mud 10-12%, desulfurization gypsum 2-2.5%, sulfoaluminate cement 5.2-5.5%, foam stabilizer 0.015-0.020%, and aluminum powder paste 0.08-0.10%.

[0015] Furthermore, the foam stabilizer in step (1) is sodium dodecylbenzenesulfonate.

[0016] Furthermore, the stirring time in step (2) is 40-80s.

[0017] Furthermore, the stirring time in step (3) is 40-80s.

[0018] Furthermore, the stirring time in step (4) is 20-40s.

[0019] Furthermore, in step (5), the static temperature of the hot chamber is 40-60° C., the humidity is 70-95% rh, and the static time is 90-110 min.

[0020] Furthermore, the specific steps of autoclave curing in step (6) are as follows: evacuating the autoclave filled with building blocks to a pressure of -0.05 MPa, raising the temperature to 1.2-1.3 MPa, maintaining constant pressure for 7-9 hours after stabilizing the pressure, and then reducing the pressure to normal pressure within 2-3 hours.

[0021] Compared with the prior art, the present invention has the following positive and beneficial effects:

[0022] The present invention adopts the method of adding sulphoaluminate cement to make the fly ash-calcium carbide mud system achieve fast coagulation and hardening and rapid early strength growth, without the need for additional alkali activator, thereby solving the problem of poor initial curing strength of autoclaved aerated concrete after calcium carbide mud replaces quicklime in the process of preparing autoclaved aerated concrete; the present invention also achieves the complete replacement of lime by calcium carbide mud, reduces carbon dioxide emissions, and on this basis, regulates the composition of various raw materials for preparing autoclaved aerated concrete, optimizes the material ratio and the static curing system, and obtains a high-performance (bulk density ≤650Kg / m 3 , autoclaved aerated concrete blocks with three-day strength ≥3.5MPa) not only solve the problem of difficult treatment of solid waste from bulk industries (polyvinyl chloride manufacturing industry), reduce production costs, save energy, reduce carbon emissions, and make full use of resources. DETAILED DESCRIPTION

[0023] The technical solution of the present invention will be further described below in conjunction with specific embodiments. However, it should be understood by those skilled in the art that the following examples are only intended to illustrate the present invention and should not be construed as limiting the present invention. Specific conditions not specified in the examples are to be followed according to conventional conditions or the conditions recommended by the manufacturer. All reagents or instruments used, unless otherwise specified, are conventional products obtained from commercial channels.

[0024] Example 1

[0025] (1) Weigh 79% fly ash, 3.2% waste aerated concrete material, 10% calcium carbide mud, 2.3% desulfurized gypsum, 5.38% sulfoaluminate cement, 0.02% sodium dodecylbenzene sulfonate, and 0.1% aluminum powder paste according to mass percentage;

[0026] (2) The fly ash, waste aerated concrete material, calcium carbide mud, desulfurized gypsum, and foam stabilizer weighed in step (1) were added to water and mixed in a blender for 60 seconds to obtain slurry A.

[0027] (3) adding the sulphoaluminate cement weighed in step (1) to the slurry A prepared in step (2), and rapidly and thoroughly mixing and stirring for 60 seconds to obtain slurry B;

[0028] (4) Add the aluminum powder paste weighed in step (1) to the slurry B obtained in step (3), and stir rapidly for 40 seconds to obtain slurry C;

[0029] (5) pouring the slurry C prepared in step (4) into a mold and placing it in a hot chamber for 95 minutes. The temperature of the hot chamber is 50° C. and the humidity is 82% r. As the gas is generated, the slurry expands and hardens, forming a green body that can be processed;

[0030] (6) Cutting the green body prepared in step (5) to obtain blocks, evacuating the autoclave filled with blocks to a pressure of -0.05 MPa, raising the temperature to 1.25 MPa, and maintaining the pressure at a constant pressure for 8 hours after stabilization, and then reducing the pressure to normal pressure within 2-3 hours to prepare sulphoaluminate cement-carbide mud autoclaved aerated concrete.

[0031] Example 2

[0032] (1) Weigh 78% fly ash, 4% waste aerated concrete material, 10.49% calcium carbide mud, 2.2% desulfurized gypsum, 5.2% sulfoaluminate cement, 0.02% sodium dodecylbenzene sulfonate, and 0.09% aluminum powder paste according to mass percentage;

[0033] (2) The fly ash, waste aerated concrete material, calcium carbide mud, desulfurized gypsum, and foam stabilizer weighed in step (1) were added to water and mixed in a blender for 50 seconds to obtain slurry A.

[0034] (3) adding the sulphoaluminate cement weighed in step (1) to the slurry A prepared in step (2), and rapidly and thoroughly mixing and stirring for 45 seconds to obtain slurry B;

[0035] (4) Add the aluminum powder paste weighed in step (1) to the slurry B obtained in step (3), and stir rapidly for 35 seconds to obtain slurry C;

[0036] (5) pouring the slurry C prepared in step (4) into a mold and placing it in a hot chamber for 100 minutes. The temperature of the hot chamber is 55° C. and the humidity is 87% r. As the gas is generated, the slurry expands and hardens, forming a green body that can be processed;

[0037] (6) Cutting the green body prepared in step (5) to obtain blocks, evacuating the autoclave containing the blocks to a pressure of -0.05 MPa, raising the temperature to 1.3 MPa, maintaining a constant pressure for 8 hours, and then reducing the pressure to normal pressure within 2-3 hours. Thus, sulphoaluminate cement-carbide mud autoclaved aerated concrete is prepared.

[0038] Example 3

[0039] (1) Weigh 78% fly ash, 3.5% waste aerated concrete material, 11% calcium carbide mud, 2.18% desulfurized gypsum, 5.2% sulfoaluminate cement, 0.02% sodium dodecylbenzene sulfonate, and 0.1% aluminum powder paste according to mass percentage;

[0040] (2) The fly ash, waste aerated concrete material, calcium carbide mud, desulfurized gypsum, and foam stabilizer weighed in step (1) were added to water and mixed in a blender for 55 seconds to obtain slurry A.

[0041] (3) adding the weighed sulphoaluminate cement from step (1) to the slurry A prepared from step (2), and rapidly and thoroughly mixing and stirring for 55 seconds to obtain slurry B;

[0042] (4) Add the aluminum powder paste weighed in step (1) to the slurry B obtained in step (3), and stir rapidly for 30 seconds to obtain slurry C;

[0043] (5) pouring the slurry C prepared in step (4) into a mold and placing it in a hot chamber for 105 minutes. The temperature of the hot chamber is 48° C. and the humidity is 76% r. As the gas is generated, the slurry expands and hardens, forming a green body that can be processed;

[0044] (6) Cutting the green body prepared in step (5) to obtain blocks, evacuating the autoclave containing the blocks to a pressure of -0.05 MPa, raising the temperature to 1.2 MPa, maintaining a constant pressure for 8 hours, and then reducing the pressure to normal pressure within 2-3 hours to prepare sulphoaluminate cement-carbide mud autoclaved aerated concrete.

[0045] Comparative Example 1

[0046] (1) Weigh 78% fly ash, 4% waste aerated concrete material, 10.49% quicklime, 2.2% desulfurized gypsum, 5.2% sulfoaluminate cement, 0.02% sodium dodecylbenzene sulfonate, and 0.09% aluminum paste by mass;

[0047] (2) The fly ash, waste aerated concrete material, quicklime, desulfurized gypsum, and foam stabilizer weighed in step (1) were added to water and mixed in a blender for 60 seconds to obtain slurry A.

[0048] (3) adding the sulphoaluminate cement weighed in step (1) to the slurry A prepared in step (2), and rapidly and thoroughly mixing and stirring for 60 seconds to obtain slurry B;

[0049] (4) Add the aluminum powder paste weighed in step (1) to the slurry B obtained in step (3), and stir rapidly for 40 seconds to obtain slurry C;

[0050] (5) pouring the slurry C prepared in step (4) into a mold and placing it in a hot chamber for 95 minutes. The temperature of the hot chamber is 50° C. and the humidity is 82% r. As the gas is generated, the slurry expands and hardens, forming a green body that can be processed;

[0051] (6) Cutting the green body prepared in step (5) to obtain blocks, evacuating the autoclave filled with blocks to a pressure of -0.05 MPa, raising the temperature to 1.25 MPa, and maintaining the pressure at a constant pressure for 8 hours after stabilization, and then reducing the pressure to normal pressure within 2-3 hours to prepare sulphoaluminate cement-carbide mud autoclaved aerated concrete.

[0052] Comparative Example 2

[0053] (1) Weigh 78% fly ash, 4% waste aerated concrete material, 10.49% quicklime, 2.2% desulfurized gypsum, 5.2% sulfoaluminate cement, 0.02% sodium dodecylbenzene sulfonate, and 0.09% aluminum paste by mass;

[0054] (2) The fly ash, waste aerated concrete material, calcium carbide mud, desulfurized gypsum, and foam stabilizer weighed in step (1) were added to water and mixed in a blender for 60 seconds to obtain slurry A.

[0055] (3) adding the sulphoaluminate cement weighed in step (1) to the slurry A prepared in step (2), and rapidly and thoroughly mixing and stirring for 60 seconds to obtain slurry B;

[0056] (4) Add the aluminum powder paste weighed in step (1) to the slurry B obtained in step (3), and stir rapidly for 40 seconds to obtain slurry C;

[0057] (5) pouring the slurry C prepared in step (4) into a mold and placing it in a hot chamber for 95 minutes. The temperature of the hot chamber is 50° C. and the humidity is 82% r. As the gas is generated, the slurry expands and hardens, forming a green body that can be processed;

[0058] (6) Cutting the green body prepared in step (5) to obtain blocks, evacuating the autoclave filled with blocks to a pressure of -0.05 MPa, raising the temperature to 1.25 MPa, and maintaining the pressure at a constant pressure for 8 hours after stabilization, and then reducing the pressure to normal pressure within 2-3 hours to prepare sulphoaluminate cement-carbide mud autoclaved aerated concrete.

[0059] Test example

[0060] The concrete obtained from Examples 1-3 and Comparative Examples 1-2 of the present invention were subjected to performance tests in accordance with the requirements of "Test Methods for Performance of Autoclaved Aerated Concrete" GB / T11698. The specific test results are shown in Table 1.

[0061] Table 1 Performance test data of autoclaved aerated concrete obtained from Examples 1-3 and Comparative Examples 1-2

[0062]

[0063]

[0064] As can be seen from the data in Table 1, the present invention adopts the method of adding sulphoaluminate cement to make the fly ash-calcium carbide mud system achieve fast coagulation and hardening and rapid early strength growth, without the need for additional alkali activator, thereby solving the problem of poor initial curing strength of autoclaved aerated concrete after calcium carbide mud replaces quicklime in the process of preparing autoclaved aerated concrete; and the present invention achieves the complete replacement of quicklime by calcium carbide mud, reduces carbon dioxide emissions, and on this basis, regulates the composition of each raw material in the preparation of autoclaved aerated concrete, optimizes the material ratio and the static curing system, and obtains a high performance (bulk density ≤ 650Kg / m 3 , autoclaved aerated concrete blocks with three-day strength ≥3.5MPa)

[0065] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing sulphoaluminate cement-carbide mud autoclaved aerated concrete, characterized in that: The preparation method comprises the following steps: (1) Weigh fly ash, waste aerated concrete material, calcium carbide mud, desulfurized gypsum, sulfoaluminate cement, foam stabilizer, and aluminum powder paste according to mass percentage; (2) adding the fly ash, waste aerated concrete material, calcium carbide mud, desulfurized gypsum and foam stabilizer weighed in step (1) into water, and mixing and stirring in a blender to obtain slurry A; (3) adding the sulphoaluminate cement weighed in step (1) to the slurry A obtained in step (2), and quickly and thoroughly mixing and stirring to obtain slurry B; (4) adding the aluminum powder paste weighed in step (1) to the slurry B obtained in step (3) and stirring rapidly to obtain slurry C; (5) pouring the slurry C obtained in step (4) into a mold, placing it in a hot chamber and allowing it to stand for a while, and forming a green body that can be processed as it expands, thickens, and hardens with gas; (6) Cutting and processing the green body obtained in step (5), and autoclaving and curing to prepare sulphoaluminate cement-carbide mud autoclaved aerated concrete.

2. The method for preparing a sulphoaluminate cement-carbide mud autoclaved aerated concrete according to claim 1, wherein: The mass percentages of the components in step (1) are: fly ash 75-79%, waste aerated concrete material 3.2-5%, calcium carbide mud 10-12%, desulfurization gypsum 2-2.5%, sulphoaluminate cement 5.2-5.5%, foam stabilizer 0.015-0.020%, and aluminum powder paste 0.08-0.10%.

3. The method for preparing a sulphoaluminate cement-carbide mud autoclaved aerated concrete according to claim 1, wherein: The foam stabilizer in step (1) is sodium dodecylbenzenesulfonate.

4. The method for preparing a sulphoaluminate cement-carbide mud autoclaved aerated concrete according to claim 1, wherein: The stirring time in step (2) is 40-80s.

5. The method for preparing a sulphoaluminate cement-carbide mud autoclaved aerated concrete according to claim 1, wherein: The stirring time in step (3) is 40-80s.

6. The method for preparing a sulphoaluminate cement-carbide mud autoclaved aerated concrete according to claim 1, wherein: The stirring time in step (4) is 20-40s.

7. The method for preparing a sulphoaluminate cement-carbide mud autoclaved aerated concrete according to claim 1, wherein: In the step (5), the static temperature of the hot chamber is 40-60° C., the humidity is 70-95% rh, and the static time is 90-110 min.

8. The method for preparing a sulphoaluminate cement-carbide mud autoclaved aerated concrete according to claim 1, wherein: The specific steps of autoclave curing in step (6) are as follows: evacuating the autoclave filled with building blocks to a pressure of -0.05 MPa, raising the temperature to 1.2-1.3 MPa, curing at a constant pressure for 7-9 hours after stabilizing the pressure, and then reducing the pressure to normal pressure within 2-3 hours.

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