Autoclaved aerated concrete component based on bentonite as well as preparation method and application of autoclaved aerated concrete component

Abstract

The present invention discloses a bentonite-based autoclaved aerated concrete component, and relates to the technical field of buildings, the bentonite-based autoclaved aerated concrete component comprises a base material and water, the base material comprises 65-70% of bentonite slurry, 3-4.5% of fly ash, 6.8-8.8% of quicklime powder, 2.45-3% of gypsum and 16.7-20% of cement, the water-to-material ratio of the water to the base material is 0.68-0.72, and the bentonite-based autoclaved aerated concrete component further comprises a foaming agent, the weight of the foaming agent is 0.33%-0.34% of the dry weight of the base material. The autoclaved aerated concrete is prepared by matching the high-proportion bentonite slurry, fly ash, quicklime powder, gypsum and cement, so that the strength of a finished product can be improved, the expansive force is inhibited, the characteristics of bentonite are fully utilized, and the production cost is reduced. Compared with a traditional autoclaved aerated concrete produced by taking sandy soil as a main raw material and bentonite as an additive, the autoclaved aerated concrete has the characteristics of light weight and higher strength, and resource utilization of the bentonite is utilized.

Description

Technical Field

[0001] The present invention relates to the field of building technology, and in particular to a bentonite-based autoclaved aerated concrete component, a preparation method and application thereof. Background Art

[0002] Autoclaved aerated concrete (AAC) is a cement-based porous material formed by uniformly mixing cement slurry with prefabricated foam from a blowing agent, followed by hardening. It boasts multifunctional properties such as lightweight, self-insulating, flame-retardant, earthquake-resistant, and sound-insulating. Therefore, it is widely used in self-insulating finished products, cast-in-place insulated walls, and exterior wall insulation panels. In existing technologies, bentonite is added to AAC to address issues with pore distribution and structure. In the application of AAC, bentonite is typically used as an additive in combination with sand. However, bentonite-based AAC has not yet been documented. Summary of the Invention

[0003] In view of the existing technology, a bentonite-based autoclaved aerated concrete component is proposed. The autoclaved aerated concrete produced with bentonite as the main raw material can have the characteristics of light weight and high strength of traditional autoclaved aerated concrete products produced with sand as the main raw material.

[0004] The present invention provides a bentonite-based autoclaved aerated concrete component. Bentonite is added to cement slurry to improve the strength and thermal insulation properties of the autoclaved aerated concrete. The specific technical solution is as follows: a base material and water. The base material comprises 65% to 70% bentonite slurry, 3% to 4.5% fly ash, 6.8% to 8.8% quicklime powder, 2.45% to 3% gypsum, and 16.7% to 20% cement. The water-to-base material ratio is 0.68 to 0.72. A foaming agent is also included, with the foaming agent comprising 0.33% to 0.34% of the base material's dry weight.

[0005] Preferably, the fineness of the bentonite is less than or equal to 42%;

[0006] Preferably, the foaming agent includes aluminum powder or aluminum powder paste.

[0007] Preferably, the silicon-calcium ratio of the bentonite-based autoclaved aerated concrete component is between 0.7 and 0.8.

[0008] A second aspect of the present invention provides a method for preparing bentonite-based autoclaved aerated concrete, comprising the following steps:

[0009] S1: Add bentonite slurry, quicklime powder, cement, fly ash, gypsum and water into a container and mix them, then add a foaming agent to obtain a mixed slurry;

[0010] S2: Pour the mixed slurry into the mold frame to foam into a blank and then maintain it at a constant temperature and allow it to gasify and stop;

[0011] S3: cutting and demoulding;

[0012] S4: sending the concrete into the autoclave for autoclaving and curing with high-temperature saturated steam to obtain the finished autoclaved aerated concrete product.

[0013] Preferably, before step S1, the process further comprises preparing bentonite slurry, wherein the preparation step of the bentonite slurry is as follows: taking the bentonite, adding water, grinding the slurry, and sieving the slurry through an 80 mm sieve to obtain the bentonite slurry.

[0014] Preferably, the constant temperature range is 45°C to 55°C.

[0015] Preferably, the gas generation static time is 2h to 3.5h.

[0016] A third aspect of the present invention provides an application of bentonite-based autoclaved aerated concrete, and an application of the autoclaved aerated concrete obtained by the above-mentioned preparation method of autoclaved aerated concrete in building materials.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The combination of high-proportion bentonite slurry, fly ash, quicklime powder, gypsum and cement to produce autoclaved aerated concrete can increase the strength of the finished product, inhibit expansion force, and fully utilize the characteristics of bentonite. Compared with traditional autoclaved aerated concrete produced with sand as the main raw material and bentonite as an additive, the product has the characteristics of lighter weight and higher strength. The resource utilization of bentonite is in line with the national industrial policy of comprehensive resource utilization and circular economy, and has significant economic, social and environmental benefits. DETAILED DESCRIPTION

[0019] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0020] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0021] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0022] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0023] Although the addition of bentonite can make the pore distribution of autoclaved aerated concrete uniform, a high amount of bentonite will increase the slurry consistency of the autoclaved aerated concrete, thereby reducing the quality of the finished autoclaved aerated concrete. In the prior art, measures are taken to add more bentonite, such as modifying the bentonite, but the maximum amount of bentonite added does not exceed 50%.

[0024] In view of this, the present invention provides a bentonite-based autoclaved aerated concrete component, comprising: a base material and water, wherein the base material comprises 65% to 70% bentonite slurry, 3% to 4.5% fly ash, 6.8% to 8.8% quicklime powder, 2.45% to 3% gypsum and 16.7% to 20% cement, and the water-to-material ratio of the water to the base material is 0.68 to 0.72. The present invention also includes a foaming agent, and the foaming agent is 0.33% to 0.34% of the dry weight of the base material.

[0025] Bentonite, also known as bentonite, is a clay-type mineral primarily belonging to the montmorillonite family. Its primary component is aluminosilicate. Its calcined product contains approximately 50% to 75% SiO2 and 15% to 25% Al2O3, followed by iron, magnesium, calcium, sodium, potassium, and titanium. It also contains certain trace elements essential for animal life, such as zinc, copper, manganese, and cobalt. Bentonite has a relative density of 2.4 to 2.8 and possesses greater water absorption and adsorption capacity than typical clays. Upon absorbing water, its volume expands by 10 to 15 times its dry mass. It also exhibits a strong base-cation exchange capacity.

[0026] Specifically, fly ash increases the air permeability and water absorption of the green body, effectively solves the adhesion problem, and is conducive to autoclaving and curing. The quality requirements of quicklime powder are: effective calcium > 70%, magnesium oxide < 3%, and digestion time 8 to 15 minutes. The addition of quicklime powder can adjust the thickening speed of the mixed slurry, provide the temperature required in the pre-curing stage, and allow the autoclaved aerated concrete green body to slowly gasify at a steadily rising temperature, reducing the impact of green body shrinkage and sinking, adjusting the pH of the green body, and providing calcium elements for cement hydration reaction. Gypsum can adjust the thickening and gasification speed of the mixed slurry, provide sulfate for the hydration reaction in the later steam curing process, and provide a certain strength for the finished autoclaved aerated concrete product. In the pre-curing stage of the green body, cement gives the green body a certain strength, which is convenient for demoulding and cutting, and participates in the hydration synthesis reaction to form strength during the autoclaving and curing process.

[0027] Furthermore, the chemical composition of quicklime powder is mainly CaO. When added to bentonite, corresponding physical changes and chemical reactions will occur, resulting in the continuous increase in the stiffness, strength and water stability of the lime soil. Its mechanism of action is generally the following four: ① Cation exchange: After quicklime powder is mixed with bentonite, excessive CaO will be generated in the bentonite. 2+ , it can replace other low-valent ions in bentonite; ② Flocculation or agglomeration: mainly turns small particles in bentonite into large agglomerates; ③ Carbonization: the quicklime powder in bentonite reacts with carbon dioxide in the air to form CaCO3 crystals; ④ Cementation: an appropriate amount of quicklime powder and water can react with a large amount of silicon, aluminum or both in bentonite to produce a strong adhesive substance. In this highly alkaline environment, calcium aluminum hydroxide is mainly produced. Under the combined effect of the above factors, the structure of bentonite has also undergone major changes.

[0028] Eliminating the destructive expansion of bentonite is a key link in bentonite construction. After quicklime powder is added to bentonite, the two undergo physical and chemical reactions, including ion exchange, Ca(OH)2 crystallization, carbonation and volcanic ash reaction; the Ca ions after Ca(OH)2 dissociation exchange with the K ions and Na ions on the clay colloid antiparticle layer, the colloid adsorption layer becomes thinner, and the colloid particles agglomerate; the water-containing crystals formed by the reaction of Ca(OH)2 with water cement the clay particles into a whole, and the carbonation reaction in the process of forming CaCO3 and the volcanic ash reaction in the process of forming calcium silicate and calcium aluminate both change the mechanical properties of bentonite, greatly improving its strength and water stability, and controlling its swelling and shrinkage.

[0029] In an optional embodiment, the fineness of the bentonite is less than or equal to 42%. If the bentonite is too coarse, it will sink in the slurry, resulting in uneven material distribution in the green body and cracks. Therefore, controlling the fineness of the bentonite can improve the product strength, bulk density and product quality.

[0030] In an optional embodiment, the foaming agent includes aluminum powder or aluminum powder paste.

[0031] In an optional embodiment, the silicon-calcium ratio of the bentonite-based autoclaved aerated concrete component is between 0.7 and 0.8, including but not limited to 0.7, 0.74, 0.76, 0.79 and 0.8.

[0032] The present invention also provides a bentonite-based autoclaved aerated concrete product, which has the characteristics of high strength, low expansion force and light weight, and fully utilizes the properties of bentonite.

[0033] In addition, the present invention also provides a method for preparing the bentonite-based autoclaved aerated concrete as described above. In this embodiment, the preparation method includes the following steps:

[0034] S1: Add bentonite slurry, quicklime powder, cement, fly ash, gypsum and water into a container and mix them, then add a foaming agent to obtain a mixed slurry;

[0035] S2: Pour the mixed slurry into the mold frame to foam into a blank and then maintain it at a constant temperature and allow it to gasify and stop;

[0036] S3: cutting and demoulding;

[0037] S4: sending the concrete into the autoclave for autoclaving and curing with high-temperature saturated steam to obtain the finished autoclaved aerated concrete product.

[0038] In an optional embodiment, before step S1, the process further includes preparing bentonite slurry. The preparation steps of the bentonite slurry are as follows: taking the bentonite, adding water, grinding and slurrying, and sieving through an 80 mm sieve to obtain the bentonite slurry.

[0039] In an optional embodiment, the constant temperature range is 45° C. to 55° C., including but not limited to 45° C., 48° C., 50° C., 53° C. and 55° C., at which the autoclaved aerated concrete is foamed to make the bubbles uniform.

[0040] In an optional embodiment, the gas generation static time is 2h to 3.5h.

[0041] The technical solutions of the present invention are further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0042] Example 1

[0043] 65% bentonite slurry, 3% fly ash, 6.8% quicklime powder, 2.45% gypsum and 16.7% cement are mixed with a water-to-base material ratio of 0.68 and a foaming agent of 0.33% of the dry weight of the base material to obtain a mixed slurry. The mixed slurry is poured into a mold frame for foaming into a blank for curing, and is cured at a constant temperature of 45°C and allowed to stand for 2 hours to generate gas. The blank is then cut, demolded and sent into an autoclave for curing with high-temperature saturated steam to obtain a finished autoclaved aerated concrete product.

[0044] Example 2

[0045] 70% bentonite slurry, 3% fly ash, 6.8% quicklime powder, 2.45% gypsum and 16.7% cement are mixed with a water-to-base material ratio of 0.68 and a foaming agent of 0.33% of the dry weight of the base material to obtain a mixed slurry. The mixed slurry is poured into a mold frame for foaming into a blank for curing, and is cured at a constant temperature of 45°C and allowed to stand for 2 hours to generate gas. Then, the blank is cut, demolded and sent into an autoclave for curing with high-temperature saturated steam to obtain a finished autoclaved aerated concrete product.

[0046] Example 3

[0047] 65% bentonite slurry, 3% fly ash, 6.8% quicklime powder, 2.45% gypsum and 20% cement are mixed with a water-to-base material ratio of 0.68 and a foaming agent of 0.33% of the dry weight of the base material to obtain a mixed slurry. The mixed slurry is poured into a mold frame for foaming into a blank for curing, and is cured at a constant temperature of 50°C and allowed to stand for 2.5 hours to generate gas. The blank is then cut and demolded and sent into an autoclave for curing with high-temperature saturated steam to obtain a finished autoclaved aerated concrete product.

[0048] Example 4

[0049] 68% bentonite slurry, 3% fly ash, 6.8% quicklime powder, 2.45% gypsum and 16.7% cement are mixed with a water-to-base material ratio of 0.68 and a foaming agent of 0.33% of the dry weight of the base material to obtain a mixed slurry. The mixed slurry is poured into a mold frame for foaming into a blank for curing, and is cured at a constant temperature of 55°C and allowed to stand for 3 hours to generate gas. The blank is then cut, demolded and sent into an autoclave for curing with high-temperature saturated steam to obtain a finished autoclaved aerated concrete product.

[0050] Example 5

[0051] 68% bentonite slurry, 4.5% fly ash, 8.8% quicklime powder, 3% gypsum and 20% cement are mixed with a water-to-base material ratio of 0.72 and a foaming agent of 0.34% of the dry weight of the base material to obtain a mixed slurry. The mixed slurry is poured into a mold frame for foaming into a blank for curing, and is cured at a constant temperature of 45°C and allowed to stand for 3.5 hours to generate gas. The blank is then cut and demolded and sent into an autoclave for curing with high-temperature saturated steam to obtain a finished autoclaved aerated concrete product.

[0052] Comparative Example 1

[0053] 65% sand, 3% fly ash, 6.8% quicklime powder, 2.45% gypsum and 16.7% cement are mixed with a water-to-base material ratio of 0.68 and a foaming agent of 0.33% of the dry weight of the base material to obtain a mixed slurry. The mixed slurry is poured into a mold frame for foaming into a blank for curing, and is cured at a constant temperature of 45°C and allowed to stand for 2 hours to generate gas. Then, the blank is cut, demolded and sent into an autoclave for curing with high-temperature saturated steam to obtain a finished autoclaved aerated concrete product.

[0054] Comparative Example 2

[0055] 70% sand, 3% fly ash, 6.8% quicklime powder, 2.45% gypsum and 16.7% cement are mixed with a water-to-base material ratio of 0.68 and a foaming agent of 0.33% of the dry weight of the base material to obtain a mixed slurry. The mixed slurry is poured into a mold frame for foaming into a blank for curing, and is cured at a constant temperature of 45°C and allowed to stand for 2 hours to generate gas. Then, the blank is cut, demolded and sent into an autoclave for curing with high-temperature saturated steam to obtain a finished autoclaved aerated concrete product.

[0056] The bentonite-based autoclaved aerated concrete products prepared in Examples 1 to 5 and the autoclaved aerated concrete boards prepared in Comparative Examples 1 to 2 were subjected to performance tests, and the results are shown in Table 1 below.

[0057] Table 1 Performance test structure

[0058]

[0059] As can be seen from Table 1, the compressive strength of the autoclaved aerated concrete products prepared in the embodiments of the present invention is above 5.2 MPa, which is a high compressive strength. At the same time, the thermal conductivity coefficients of Comparative Examples 1 and 2 are generally higher than that of the embodiments, indicating that the combination of high proportions of bentonite slurry, fly ash, quicklime powder, gypsum and cement improves the thermal insulation properties of the autoclaved aerated concrete products.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of the patent application of the present invention. Any equivalent changes, equivalent replacements or modified changes within the technical spirit and principles suggested by the present invention should be included in the scope of patent protection covered by the present invention.

Claims

1. An autoclaved aerated concrete component based on bentonite, characterized in that include: The base material and water include 65% to 70% bentonite slurry, 3% to 4.5% fly ash, 6.8% to 8.8% quicklime powder, 2.45% to 3% gypsum and 16.7% to 20% cement, the water-to-base material ratio is 0.68 to 0.72, and the base material also includes a foaming agent, and the foaming agent is 0.33% to 0.34% of the dry weight of the base material.

2. The bentonite-based autoclaved aerated concrete component according to claim 1, characterized in that The fineness of the bentonite is less than or equal to 42%.

3. The bentonite-based autoclaved aerated concrete component according to claim 1, characterized in that The foaming agent includes aluminum powder or aluminum powder paste.

4. The bentonite-based autoclaved aerated concrete component according to claim 1, characterized in that The silicon-calcium ratio of the bentonite-based autoclaved aerated concrete component is 0.7-0.

8.

5. A method for preparing bentonite-based autoclaved aerated concrete according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1: Add bentonite slurry, quicklime powder, cement, fly ash, gypsum and water into a container and mix them, then add a foaming agent to obtain a mixed slurry; S2: Pour the mixed slurry into the mold frame to foam into a blank and then maintain it at a constant temperature and allow it to gasify and stop; S3: cutting and demoulding; S4: sending the concrete into the autoclave for autoclaving and curing with high-temperature saturated steam to obtain the finished autoclaved aerated concrete product.

6. The method for preparing bentonite-based autoclaved aerated concrete according to claim 5, characterized in that: Before step S1, the process also includes preparing bentonite slurry. The preparation steps of the bentonite slurry are as follows: taking the bentonite, adding water, grinding and slurrying, and sieving through an 80 mm sieve to obtain the bentonite slurry.

7. The method for preparing bentonite-based autoclaved aerated concrete according to claim 5, characterized in that: The constant temperature range is 45°C to 55°C.

8. The method for preparing bentonite-based autoclaved aerated concrete according to claim 5, wherein: The gas generation static stop time is 2h to 3.5h.

9. An application of bentonite-based autoclaved aerated concrete, characterized in that: Application of the autoclaved aerated concrete obtained by the preparation method of autoclaved aerated concrete as claimed in claim 5 in building materials.

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