A non-autoclaved aerated concrete and a method for producing the same

Abstract

The present application relates to the technical field of building materials, and particularly relates to a steam-curing-free aerated concrete and a preparation method thereof, which comprises the following components in percentage by mass: fly ash 30-47%, coal gangue 18-35%, carbide slag 12-27%, and quicklime 15-22%; further comprising an activator and a gas-producing material, the addition amount of the activator is 2-4% of the mass of the fly ash, and the addition amount of the gas-producing material is 0.08-0.1% of the sum of the mass of the fly ash, the coal gangue, the carbide slag and the quicklime. The steam-curing-free aerated concrete of the present application uses a large amount of industrial solid waste, and the mixing amount is as high as more than 80%, which not only realizes the resource utilization of the industrial solid waste and reduces the cost of raw materials of enterprises, but also reduces the pollution to the environment and saves the use of cement; and the present application replaces the high-temperature and high-pressure steam curing mode with the normal-temperature and normal-pressure curing mode, greatly reduces the energy consumption of curing, reduces carbon emissions, and has a simple preparation process, a small dry density, high strength and considerable economic benefits.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a non-autoclaved aerated concrete and its preparation method. Background Technology

[0002] Autoclaved aerated concrete (AAC) is a lightweight, porous silicate product made primarily from siliceous materials (sand, fly ash, and silica-containing tailings) and calcareous materials (lime and cement), with the addition of a foaming agent (aluminum powder). It is produced through processes including batching, mixing, pouring, pre-curing, cutting, autoclaving, and curing. It is named AAC because it contains a large number of uniform and fine pores after aeration. AAC is characterized by its low density, high thermal insulation, fire resistance, good sound absorption, and certain strength and workability. It is one of the earliest and most widely used lightweight wall materials introduced in my country.

[0003] Most existing aerated concrete products use cement as the main binder, which leads to the depletion of mining resources and damage to the ecological environment. In addition, they generally require high-temperature and high-pressure steam curing in an autoclave to achieve the design strength requirements, resulting in high production costs and significant safety hazards in the production process. 。 Summary of the Invention

[0004] In order to overcome the shortcomings of the existing technology, the purpose of this invention is to provide a non-autoclaved aerated concrete and its preparation method, which can not only consume a large amount of industrial solid waste, but also reduce the energy consumption required for curing by adopting a non-autoclaved method.

[0005] To achieve the above objectives, the technical solution of the present invention is a non-autoclaved aerated concrete, comprising the following components by mass percentage: 30-47% fly ash, 18-35% coal gangue, 12-27% carbide slag, and 15-22% quicklime; it also includes an activator and a gas-generating material, wherein the amount of the activator added is 2-4% of the mass of the fly ash, and the amount of the gas-generating material added is 0.08-0.1% of the sum of the mass of the fly ash, the coal gangue, the carbide slag, and the quicklime.

[0006] Furthermore, the effective calcium oxide content of the quicklime should be ≥80%.

[0007] Furthermore, the gas-generating material includes any one of aluminum powder and aluminum powder paste.

[0008] Furthermore, the activator includes at least one of calcium chloride, aluminum sulfate, sodium sulfate, and sodium hydroxide.

[0009] Furthermore, the fineness of the carbide slag, the fly ash, the quicklime, and the coal gangue is ≤10% residue on a 200-mesh sieve; the fly ash is secondary or primary fly ash.

[0010] The present invention also provides a method for preparing autoclaved aerated concrete as described in any of the above claims, comprising the following steps:

[0011] S1. Weigh all the required raw materials according to the mixing ratio requirements;

[0012] S2. Pour the weighed fly ash, coal gangue, carbide slag, quicklime, and activator into the required amount of water and stir thoroughly until a uniform slurry is formed.

[0013] S3. Add the gas-generating material solution to the slurry obtained in step S2 and stir again until homogeneous;

[0014] S4. Pour the slurry obtained in step S3 into the mold and shake it slightly. Then place it in the pre-curing chamber for gas generation and pre-curing. After the dough reaches a certain size, cut off the bread head.

[0015] S5. Place the cut embryo into a curing box and cure it at 80-90℃ for 18-24 hours to obtain aerated concrete.

[0016] Furthermore, in step S2, the water temperature is controlled at 50±5℃, and the stirring time is 2-4 minutes.

[0017] Furthermore, the stirring time in step S2 shall not exceed 50 seconds.

[0018] Furthermore, in step S4, the temperature of the pre-curing room is controlled at 45-55℃, and the pre-curing time is 3-5 hours.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The autoclaved aerated concrete of the present invention makes extensive use of industrial solid waste, with a dosage of up to 80% or more. This not only enables the resource utilization of industrial solid waste and reduces the cost of raw materials for enterprises, but also reduces environmental pollution.

[0021] (2) By utilizing industrial solid waste, this invention eliminates the need for cement compared to conventional aerated concrete, thereby effectively reducing the consumption of mineral resources and carbon emissions.

[0022] (3) This invention replaces the high temperature and high pressure steam curing method with the normal temperature and pressure curing method, which greatly reduces the energy consumed in curing and reduces carbon emissions. Moreover, the preparation process is simple, and the resulting aerated concrete has low dry density and high strength, resulting in considerable economic benefits. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Although representative embodiments of the present invention have been described in detail, those skilled in the art will understand that various modifications and changes can be made to the present invention without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the embodiments, but should be defined by the appended claims and their equivalents.

[0024] This invention provides a non-autoclaved aerated concrete, comprising the following components by mass percentage: 30-47% fly ash, 18-35% coal gangue, 12-27% carbide slag, and 15-22% quicklime; it also includes an activator and a gas-generating material, wherein the amount of the activator added is 2-4% of the mass of the fly ash, and the amount of the gas-generating material added is 0.08-0.1% of the sum of the mass of the fly ash, the coal gangue, the carbide slag, and the quicklime.

[0025] The effective calcium oxide content of quicklime should be ≥80%. This invention utilizes the hydration reaction of silica and aluminum in coal gangue and fly ash (after activation by an activator) with calcium hydroxide from carbide slag and quicklime digestion. The calcium hydroxide generated during quicklime digestion can also act as an activator to further activate the fly ash, and the large amount of heat released during quicklime digestion is beneficial to the reaction. Therefore, a temperature of 80-90℃ is sufficient for the entire system to react completely, resulting in a product that meets the required performance standards.

[0026] The gas-generating material includes any one of aluminum powder or aluminum powder paste; the activator includes at least one of calcium chloride, aluminum sulfate, sodium sulfate, or sodium hydroxide; the fineness of carbide slag, fly ash, quicklime, and coal gangue is ≤10% residue on a 200-mesh sieve; the fly ash is grade II or grade I fly ash.

[0027] The present invention also provides a method for preparing the above-mentioned autoclaved aerated concrete, comprising the following steps:

[0028] S1. Weigh all the required raw materials according to the mixing ratio requirements;

[0029] S2. Pour the weighed fly ash, coal gangue, carbide slag, quicklime, and activator into the required water, control the water temperature at 50±5℃, stir thoroughly for 2-4 minutes until a uniform slurry is formed.

[0030] S3. Add the gas-generating material solution to the slurry obtained in step S2, and stir again until uniform. The stirring time should not exceed 50 seconds.

[0031] S4. Pour the slurry obtained in step S3 into the mold and shake it slightly. Then place it in the pre-curing chamber. The temperature of the pre-curing chamber is controlled at 45-55℃. Propagate and pre-cur for 3-5 hours. After the dough reaches a certain size, cut off the bread head.

[0032] S5. Place the cut embryo into a curing box and cure it at 80-90℃ for 18-24 hours to obtain aerated concrete.

[0033] The performance of the autoclaved aerated concrete of the present invention will be described in detail below through specific embodiments.

[0034] Example 1

[0035] This embodiment provides a non-autoclaved aerated concrete, comprising the following components by mass percentage: 30% fly ash, 28% coal gangue, 27% carbide slag, and 15% quicklime; it also includes calcium chloride and aluminum powder, wherein the amount of calcium chloride added is 2% of the mass of fly ash, and the amount of aluminum powder added is 0.1% of the sum of the mass of fly ash, coal gangue, carbide slag, and quicklime.

[0036] Among them, the fineness of carbide slag, fly ash, quicklime, and coal gangue is ≤10% residue on a 200-mesh sieve; the fly ash is grade II or grade I fly ash.

[0037] The above-mentioned method for preparing autoclaved aerated concrete includes the following steps:

[0038] S1. Weigh all the required raw materials according to the mixing ratio requirements;

[0039] S2. Pour the weighed fly ash, coal gangue, carbide slag, quicklime, and activator into the required water, control the water temperature at 50℃, stir thoroughly for 3 minutes until a uniform slurry is formed.

[0040] S3. Add aluminum powder solution to the slurry obtained in step S2, stir again until uniform, and stir for 40 seconds. The water-to-material ratio of the resulting slurry is 0.6.

[0041] S4. Pour the slurry obtained in step S3 into the mold and shake it slightly. Then place it in the pre-curing chamber. The temperature of the pre-curing chamber is controlled at 50℃. Perform gas generation and pre-curing for 4 hours. After the dough reaches a certain size, cut off the bread head.

[0042] S5. Place the cut embryo into a curing box and cure it at 90℃ for 18 hours to obtain aerated concrete.

[0043] Example 2

[0044] This embodiment provides a non-autoclaved aerated concrete, comprising the following components by mass percentage: 47% fly ash, 18% coal gangue, 17% carbide slag, and 18% quicklime; it also includes sodium hydroxide and aluminum powder, wherein the amount of sodium hydroxide added is 4% of the mass of fly ash, and the amount of aluminum powder added is 0.08% of the sum of the mass of fly ash, coal gangue, carbide slag, and quicklime.

[0045] Among them, the fineness of carbide slag, fly ash, quicklime, and coal gangue is ≤10% residue on a 200-mesh sieve; the fly ash is grade II or grade I fly ash.

[0046] The above-mentioned method for preparing autoclaved aerated concrete includes the following steps:

[0047] S1. Weigh all the required raw materials according to the mixing ratio requirements;

[0048] S2. Pour the weighed fly ash, coal gangue, carbide slag, quicklime, and sodium hydroxide into the required water, control the water temperature at 50℃, stir thoroughly for 3 minutes until a uniform slurry is formed.

[0049] S3. Add aluminum powder solution to the slurry obtained in step S2, stir again until uniform, and stir for 45 seconds. The water-to-material ratio of the resulting slurry is 0.62.

[0050] S4. Pour the slurry obtained in step S3 into the mold and shake it slightly. Then place it in the pre-curing chamber. The temperature of the pre-curing chamber is controlled at 50℃. Perform gas generation and pre-curing for 4 hours. After the dough reaches a certain size, cut off the bread head.

[0051] S5. Place the cut embryo into a curing box and cure it at 80℃ for 24 hours to obtain aerated concrete.

[0052] Example 3

[0053] This embodiment provides a non-autoclaved aerated concrete, comprising the following components by mass percentage: 31% fly ash, 35% coal gangue, 12% carbide slag, and 22% quicklime; it also includes calcium chloride and aluminum powder, wherein the amount of calcium chloride added is 2% of the mass of fly ash, and the amount of aluminum powder added is 0.1% of the sum of the mass of fly ash, coal gangue, carbide slag, and quicklime.

[0054] Among them, the fineness of carbide slag, fly ash, quicklime, and coal gangue is ≤10% residue on a 200-mesh sieve; the fly ash is grade II or grade I fly ash.

[0055] The above-mentioned method for preparing autoclaved aerated concrete includes the following steps:

[0056] S1. Weigh all the required raw materials according to the mixing ratio requirements;

[0057] S2. Pour the weighed fly ash, coal gangue, carbide slag, quicklime, and calcium chloride into the required water, control the water temperature at 45℃, stir thoroughly for 4 minutes until a uniform slurry is formed.

[0058] S3. Add aluminum powder solution to the slurry obtained in step S2, stir again until uniform, and stir for 45 seconds. The water-to-material ratio of the resulting slurry is 0.64.

[0059] S4. Pour the slurry obtained in step S3 into the mold and shake it slightly. Then place it in the pre-curing chamber. The temperature of the pre-curing chamber is controlled at 45℃. Perform gas generation and pre-curing for 5 hours. After the dough reaches a certain size, cut off the bread head.

[0060] S5. Place the cut embryo into a curing box and cure it at 80℃ for 24 hours to obtain aerated concrete.

[0061] Comparative Example 1

[0062] The aerated concrete provided in Comparative Example 1 comprises the following components by mass percentage: 15% cement, 67% quartz sand, 15% quicklime, and 3% gypsum; it also includes aluminum powder, which is 0.08% of the sum of the mass of cement, quartz sand, quicklime, and gypsum.

[0063] The above-mentioned method for preparing aerated concrete includes the following steps:

[0064] S1. Weigh all the required raw materials according to the mixing ratio requirements;

[0065] S2. Pour the weighed cement, quartz sand, quicklime, and gypsum into the required water, control the water temperature at 50℃, and stir thoroughly for 3 minutes until a uniform slurry is formed.

[0066] S3. Add aluminum powder solution to the slurry obtained in step S2, stir again until uniform, and stir for 45 seconds. The water-to-material ratio of the resulting slurry is 0.62.

[0067] S4. Pour the slurry obtained in step S3 into the mold and shake it slightly. Then place it in the pre-curing chamber. The temperature of the pre-curing chamber is controlled at 50℃. Perform gas generation and pre-curing for 4 hours. After the dough reaches a certain size, cut off the bread head.

[0068] S5. Place the cut embryo into an autoclave and autoclave at 180℃ for 8 hours to obtain aerated concrete.

[0069] Comparative Example 2

[0070] The aerated concrete provided in Comparative Example 2 comprises the following components by mass percentage: 74% fly ash, 14% quicklime, 8% cement, and 4% gypsum; it also includes aluminum powder, which is 0.1% of the sum of the mass of fly ash, quicklime, cement, and gypsum.

[0071] The above-mentioned method for preparing aerated concrete includes the following steps:

[0072] S1. Weigh all the required raw materials according to the mixing ratio requirements;

[0073] S2. Pour the weighed fly ash, cement, quicklime, and gypsum into the required water, control the water temperature at 50℃, and stir thoroughly for 3 minutes until a uniform slurry is formed.

[0074] S3. Add aluminum powder solution to the slurry obtained in step S2, stir again until uniform, and stir for 45 seconds. The water-to-material ratio of the resulting slurry is 0.62.

[0075] S4. Pour the slurry obtained in step S3 into the mold and shake it slightly. Then place it in the pre-curing chamber. The temperature of the pre-curing chamber is controlled at 50℃. Perform gas generation and pre-curing for 4 hours. After the dough reaches a certain size, cut off the bread head.

[0076] S5. Place the cut embryo into an autoclave and autoclave at 180℃ for 9 hours to obtain aerated concrete.

[0077] The aerated concrete of Examples 1-3 and Comparative Examples 1-2 after curing were dried at 105±5℃ to constant weight, and then their dry density, compressive strength and other properties were measured. The results are shown in Table 1.

[0078] Table 1. Performance of aerated concrete blocks prepared in Examples 1-3 and Comparative Examples 1-2

[0079]

[0080] As can be seen from Table 1, compared with Comparative Examples 1-2, the aerated concrete prepared in Examples 1-3 has a lower dry density and meets the strength grade requirements of standard A3.5. Therefore, this invention, which uses industrial solid waste as the main component to prepare aerated concrete, can save production resources, turn waste into treasure, reduce enterprise production costs, improve enterprise efficiency, and avoid pollution to the environment and land caused by factory waste discharge—achieving multiple benefits in one fell swoop.

[0081] Furthermore, Examples 1-3 can achieve the required strength under curing conditions of 80-90℃, while Comparative Examples 1-2 can only achieve higher strength under autoclaving conditions of 180℃. Therefore, the present invention can greatly reduce the energy consumption in the curing process of aerated concrete and play an effective role in energy conservation and emission reduction.

[0082] Compared to Comparative Example 1, Example 2 has the same strength grade A5.0, but while Comparative Example 1 has a dry density grade of B07, Example 2 has a dry density grade of only B05, resulting in a lower product density. Compared to Comparative Example 2, Examples 1-3, which also use industrial solid waste to prepare aerated concrete, have a higher solid waste content, lower dry density, and higher compressive strength. Therefore, the aerated concrete of this invention has superior performance, a wider range of applications, and effectively increases the competitiveness of enterprises.

[0083] The above examples are merely illustrative of the present invention and do not constitute a limitation on the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A type of autoclaved aerated concrete, characterized in that, The raw materials consist of fly ash, coal gangue, carbide slag, quicklime, activator, and gas-generating material; based on the total mass of fly ash, coal gangue, carbide slag, and quicklime as 100%, the proportions of each component are: fly ash 30-47%, coal gangue 18-35%, carbide slag 12-27%, and quicklime 15-22%; the amount of activator added is 2-4% of the mass of fly ash, and the amount of gas-generating material added is 0.08-0.1% of the sum of the masses of fly ash, coal gangue, carbide slag, and quicklime; the effective calcium oxide content of the quicklime should be ≥80%; the silica and aluminum in the coal gangue and fly ash undergo a hydration reaction with the calcium hydroxide from the carbide slag and quicklime digestion after activation by the activator; the preparation method of the autoclaved aerated concrete includes the following steps: S1. Weigh all the required raw materials according to the mixing ratio requirements; S2. Pour the weighed fly ash, coal gangue, carbide slag, quicklime, and activator into the required amount of water and stir thoroughly until a uniform slurry is formed. S3. Add the gas-generating material solution to the slurry obtained in step S2 and stir again until homogeneous; S4. Pour the slurry obtained in step S3 into the mold and shake it slightly. Then place it in the pre-curing chamber for gas generation and pre-curing. After the dough reaches a certain size, cut off the bread head. S5. Place the cut embryo into a curing box and cure it at 80-90℃ for 18-24 hours to obtain aerated concrete.

2. The autoclaved aerated concrete as described in claim 1, characterized in that: The gas-generating material includes any one of aluminum powder or aluminum powder paste.

3. The autoclaved aerated concrete as described in claim 1, characterized in that: The activator includes at least one of calcium chloride, aluminum sulfate, sodium sulfate, and sodium hydroxide.

4. The autoclaved aerated concrete as described in claim 1, characterized in that: The fineness of the carbide slag, the fly ash, the quicklime, and the coal gangue is ≤10% on a 200-mesh sieve; the fly ash is grade II or grade I fly ash.

5. The autoclaved aerated concrete as described in claim 1, characterized in that: In step S2, the water temperature is controlled at 50±5℃ and the stirring time is 2-4 minutes.

6. The autoclaved aerated concrete as described in claim 1, characterized in that: The stirring time in step S2 shall not exceed 50 seconds.

7. The autoclaved aerated concrete as described in claim 1, characterized in that: In step S4, the temperature of the pre-curing room is controlled at 45-55℃, and the pre-curing time is 3-5 hours.

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