Calcium supplement material for autoclaved aerated concrete and application
By using lightly calcined dolomitic limestone waste soil and expansive materials as calcium supplements, the problem of insufficient calcium in autoclaved aerated concrete was solved, improving the strength and stability of the product, achieving efficient utilization of low-quality resources, and reducing costs.
Patent Information
- Application Number
- CN202511068307.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-31
- Publication Date
- 2025-11-18
AI Technical Summary
In existing technologies, insufficient calcium in autoclaved aerated concrete (AAC) batches leads to shrinkage and sinking of the green body, large differences in density between the upper and lower parts, uneven product quality, poor stability, and a tight supply of high-quality limestone, which affects the stability of the production process and product quality.
Lightly calcined dolomitic limestone waste soil and expanding materials are used as calcium supplement materials to adjust the calcium-silicon ratio and promote the formation of tobermorite. The heat and expansion are provided by the hydration reaction of lightly calcined CaO and lightly calcined MgO to compensate for the shrinkage of the green body and improve the structural strength.
It effectively replenishes the calcium content of autoclaved aerated concrete, increases the expansion and structural density of the green body, enhances the strength and stability of the product, reduces raw material costs, and achieves efficient utilization of low-quality resources.
Smart Images
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Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of materials, and particularly relates to a calcareous supplementary material for autoclaved aerated concrete and application. BACKGROUND
[0002] The autoclaved aerated concrete is a green building material, which is made of calcareous materials (such as cement and quicklime), siliceous materials (such as quartz sand), adjusting materials (such as gypsum) and gas-forming materials (such as aluminum powder) through a series of processes. The production process of the autoclaved aerated concrete includes batching, pouring, static setting, cutting, autoclaving and packaging. The silicon-calcium ratio (CaO / SiO2 molar ratio) is a key parameter for the performance design of the autoclaved aerated concrete, which directly affects the strength, pore structure, durability of the material and each link of the production process. As an important component of the calcareous material, the hydration process of silicate minerals and effective calcium also affects the static setting process, and the quality of the static setting process directly determines the final performance of the autoclaved aerated concrete product.
[0003] The calcareous material of the autoclaved aerated concrete usually adopts cement and quicklime, and the quality of the calcareous material directly affects the quality of the final product. At present, the ordinary portland cement generally contains a large amount of admixtures, in which active components (such as slag and fly ash) and non-active components (such as limestone and sandstone) coexist. This ratio will reduce the content of effective components of the cement, especially the inert materials such as limestone do not react with the siliceous components in the autoclaving process, which seriously affects the product quality, and this phenomenon is particularly prominent in the autoclaved aerated concrete of the cement-slag-sand system.
[0004] In terms of the current situation of the industry, there are few enterprises specializing in producing quicklime for the autoclaved aerated concrete, and the quality of the commercially available quicklime fluctuates greatly. Some products have a low effective calcium content, which can easily lead to a decrease in the stability of the green body in the pouring process. In addition, although the autoclaved aerated concrete can absorb solid waste such as slag, these materials often have problems such as excessively fine fineness or unstable chemical composition, which can easily cause the sinking and shrinkage of the green body in the static setting stage, and affect the formation of tobermorite in the autoclaving process.
[0005] In view of the above problems, it is of great practical significance to develop a low-cost and high-efficiency calcareous supplementary material, which can effectively improve the stability of the production process of the autoclaved aerated concrete and improve the product quality. SUMMARY
[0006] The purpose of the present application is to provide a calcareous supplementary material for autoclaved aerated concrete, so as to solve the problems of "less calcium" in the batching of the autoclaved aerated concrete, large difference between the upper and lower bulk densities caused by the shrinkage and sinking of the green body, uneven product quality and poor stability in the prior art.
[0007] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:
[0008] The calcium supplement material for autoclaved aerated concrete comprises the following components by mass percentage: 5-25% of an expanding material; and 75%-95% of a light-burned dolomitic limestone waste soil.
[0009] In some embodiments of the present application, the calcium supplement material for autoclaved aerated concrete comprises the following components by mass percentage: 15-25% of an expanding material; and 75%-85% of a light-burned dolomitic limestone waste soil.
[0010] In one embodiment of the present application, the calcium supplement material for autoclaved aerated concrete comprises the following components by mass percentage: 20% of an expanding material; and 80% of a light-burned dolomitic limestone waste soil.
[0011] In some embodiments of the present application, the expanding material contains 40-60wt% of f-CaO, 5-18wt% of f-CaSO4, ≤12wt% of anhydrous calcium sulphoaluminate, and ≤3.5wt% of periclase.
[0012] In one embodiment of the present application, the expanding material contains 53.60wt% of f-CaO, 14.0wt% of f-CaSO4, 8.2wt% of anhydrous calcium sulphoaluminate, and 2.2wt% of periclase.
[0013] The expanding material comprises at least one of a calcium oxide-based expanding agent, a calcium sulphoaluminate-based expanding agent, and a magnesium oxide-based expanding agent.
[0014] The light-burned dolomitic limestone waste soil is a residue of dolomitic limestone after light-burning (low-temperature calcination) treatment, and contains light-burned CaO and light-burned MgO. The dolomite content of the dolomitic limestone is ≥50wt%.
[0015] In some embodiments of the present application, the calcination temperature is 850-950℃, preferably 900℃.
[0016] In some embodiments of the present application, the light-burned dolomitic limestone waste soil contains ≤4wt% of un-decomposed dolomitic limestone, and ≤18% of 80μm residue.
[0017] The second aspect of the present application discloses a preparation method of the calcium supplement material for autoclaved aerated concrete. Raw materials are prepared according to the ratio, and mixed uniformly to obtain the calcium supplement material for autoclaved aerated concrete.
[0018] The third aspect of the present application discloses an application of the calcium supplement material for autoclaved aerated concrete, which is used as a calcium material in the preparation of autoclaved aerated concrete.
[0019] In some embodiments of the present application, the ratio of the calcareous supplement material to the dry weight of the autoclaved aerated concrete is greater than 1.0% and less than or equal to 10%.
[0020] Compared with the prior art, the present application has the following beneficial effects:
[0021] The calcareous supplement material of the present application contains a high content of calcium, which can supplement the Ca content of the autoclaved aerated concrete, adjust the calcium-silicon ratio, and ensure the generation of tobermorite.
[0022] The calcareous supplement material of the present application contains light-burned CaO, which can supplement heat in the early stage to rapidly heat the slurry. After the ambient temperature rises, the anhydrous calcium sulphoaluminate and f-CaSO4 rapidly react to adjust the thickening process of the slurry; the partial hydration of f-CaO and light-burned MgO in the expansion material accelerates, causing the body to expand by itself and supplement the expansion amount, so that the expansion degree of the body meets the requirements of the autoclaved aerated concrete. With the static setting, the body will slightly shrink and sink, and the partial hydration of f-CaO and light-burned MgO continues to expand to compensate for the shrinkage and sinking. When the static setting is completed and the body enters the autoclave for curing, the remaining f-CaO and light-burned MgO promote the generation of hydrated calcium silicate such as tobermorite, and the unhydrated MgO fills between the particles, making the structure more compact and improving the structural strength.
[0023] When the calcareous supplement material of the present application is added to the cement-slag-sand autoclaved aerated concrete ingredients, the effect is more significant. The light-burned CaO provides partial heat, alkalinity, and is beneficial to the slurry gas evolution, and the stable activity of CaO and light-burned MgO can supplement the expansion amount of the body.
[0024] The present application can utilize the mine waste soil containing dolomite type at high value, effectively utilize low-quality resources, alleviate the supply crisis of high-quality limestone, promote the development of the industry in a green direction, and also reduce the cost of raw materials. DETAILED DESCRIPTION
[0025] The detailed description of the various exemplary embodiments of the present application should not be considered to limit the present application, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present application.
[0026] It should be understood that the terms described in the present application are only for describing the specific embodiments, and are not intended to limit the present application. In addition, for the numerical range in the present application, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or stated range and any other stated value or intermediate value within the stated range is also included in the present application. The upper limit and the lower limit of these smaller ranges can be independently included or excluded from the range.
[0027] Example 1
[0028] The calcium supplement material of the present application comprises: expanded material 20wt%; and calcined dolomitic limestone waste 80wt%.
[0029] The expanded material of the present example comprises f-CaO 53.60wt%, f-CaSO4 14.0wt%, calcium sulphoaluminate 8.2wt%, and periclase 2.2wt%.
[0030] The calcined dolomitic limestone waste of the present example is obtained by calcining dolomitic limestone at 900℃, and has a 80μm residue of 17%. The dolomite content of the dolomitic limestone is 86wt%. The un-decomposed dolomitic limestone content of the calcined dolomitic limestone waste is 3.5wt%.
[0031] The preparation method of the calcium supplement material of the present example is as follows: mix the expanded material and the calcined dolomitic limestone waste uniformly, and the calcium supplement material is obtained.
[0032] Example 2
[0033] The calcium supplement material of the present application comprises: expanded material 5wt%; and calcined dolomitic limestone waste 95wt%.
[0034] The expanded material of the present example comprises f-CaO 41.50wt%, f-CaSO4 18.2wt%, calcium sulphoaluminate 7.5wt%, and periclase 3.1wt%.
[0035] The calcined dolomitic limestone waste of the present example is obtained by calcining dolomitic limestone at 900℃, and has a 80μm residue of 17.5%. The dolomite content of the dolomitic limestone is 82wt%. The un-decomposed dolomitic limestone content of the calcined dolomitic limestone waste is 2.9wt%.
[0036] The preparation method of the calcium supplement material of the present example is as follows: mix the expanded material and the calcined dolomitic limestone waste uniformly, and the calcium supplement material is obtained.
[0037] Example 3
[0038] The calcium supplement material of the present application comprises: expanded material 25wt%; and calcined dolomitic limestone waste 75wt%.
[0039] The expanded material of the present example comprises f-CaO 59.4wt%, f-CaSO4 5.7wt%, calcium sulphoaluminate 12wt%, and periclase 2.9wt%.
[0040] The calcareous supplementary material of the present application is prepared by mixing the expanded material and the calcined dolomitic limestone waste soil.
[0041] The preparation method of the calcareous supplementary material of the present application is as follows: the expanded material and the calcined dolomitic limestone waste soil are mixed uniformly.
[0042] Example 4
[0043] The composition of the calcareous supplementary material of the present application is as follows: the expanded material 15wt%, the calcined dolomitic limestone waste soil 85wt%.
[0044] The expanded material contains f-CaO 48.4wt%, f-CaSO417.1wt%, anhydrous calcium sulphoaluminate 10.8wt%, and periclase 2.4wt%.
[0045] The calcined dolomitic limestone waste soil is obtained by calcining dolomitic limestone at 900℃, and the 80μm sieve residue is 17%. The dolomite content of the dolomitic limestone is 75wt%. The undecomposed dolomitic limestone content in the calcined dolomitic limestone waste soil is 2.6wt%.
[0046] The preparation method of the calcareous supplementary material of the present application is as follows: the expanded material and the calcined dolomitic limestone waste soil are mixed uniformly.
[0047] Test Example 1
[0048] The effect of adding the calcareous supplementary material on the performance of the cement-lime-sand autoclaved aerated concrete is investigated. The formula of the autoclaved aerated concrete with and without the addition of the calcareous supplementary material is shown in Table 1. The calcareous supplementary material used in the present test example is prepared according to the method of Example 1.
[0049] The preparation method of the cement-lime-sand autoclaved aerated concrete is as follows:
[0050] S1. Dissolve the aluminum powder in water; add the remaining materials in the formula to a blender, add water according to the water-material ratio in the formula, and continuously stir while heating the slurry to 45-50℃ using steam, stir for 2-3 minutes to mix uniformly, add warm water (containing dissolved aluminum powder), and stir for 40-60 seconds to form a uniform slurry;
[0051] S2. Pour the slurry into a mold, and use a steam tamping rod to comb once after pouring is completed.
[0052] S3. Push the poured mold into a static curing room with an ambient temperature of 50-60℃, and statically cure for 2.5 hours.
[0053] S4. The green body after static stop is cut into different specifications according to actual production needs.
[0054] S5. After cutting, it is sent into a steam pressure curing kettle for curing for 8 hours in a steam pressure curing kettle with a steam pressure of 1.2 MPa and a temperature of 185°C.
[0055] The obtained autoclaved aerated concrete block is detected according to GB / T11969-2020 "Performance Test Method of Autoclaved Aerated Concrete", and the results are shown in Table 1.
[0056] Table 1: Cement-lime-sand autoclaved aerated concrete formula and performance
[0057]
[0058] As can be seen from Table 1, after adding calcium supplementary material, the dry density of cement-lime-sand autoclaved aerated concrete decreases, and the strength increases significantly, and the performance meets the technical requirements of A3.5B06 grade in GB / T11968-2020 "Autoclaved Aerated Concrete Block".
[0059] Test Example 2
[0060] This test example investigates the influence of adding calcium supplementary material on the performance of cement-lime-fly ash autoclaved aerated concrete. The formula of autoclaved aerated concrete with and without calcium supplementary material is shown in Table 2. The calcium supplementary material used in this test example is prepared according to the method of Example 1.
[0061] The preparation method of cement-lime-fly ash autoclaved aerated concrete is as follows:
[0062] S1. Dissolve aluminum powder in water; add the remaining materials in the formula to a blender, add water according to the water material ratio in the ingredients, and continuously stir while heating the slurry to 45-50°C using steam, stir for 2-3 minutes to mix evenly, add warm water (containing dissolved aluminum powder), and stir for 40-60 seconds to form a uniform slurry;
[0063] S2. Pour the slurry into a mold, and after pouring is completed, use a steam rammer to comb once.
[0064] S3. Push the poured mold into a static curing room with an ambient temperature of 50-60°C, and static curing for 2.5 hours.
[0065] S4. The green body after static stop is cut into different specifications according to actual production needs.
[0066] S5. After cutting, it is sent into a steam pressure curing kettle for curing for 8 hours in a steam pressure curing kettle with a steam pressure of 1.2 MPa and a temperature of 185°C.
[0067] The obtained autoclaved aerated concrete blocks were detected according to GB / T11969-2020 "Method for testing the performance of autoclaved aerated concrete", and the results are shown in Table 2.
[0068] Table 2: Cement-lime-fly ash autoclaved aerated concrete formula and performance
[0069]
[0070] As can be seen from Table 2, after adding calcium supplementary material, the dry density of cement-lime-fly ash autoclaved aerated concrete decreases, and the strength significantly increases, and the performance meets the technical requirements of A3.5 B06 grade in GB / T11968-2020 "Autoclaved aerated concrete block".
[0071] Test Example 3
[0072] This test example investigates the effect of adding calcium supplementary material on the performance of cement-slag-sand autoclaved aerated concrete. The formula of autoclaved aerated concrete with and without calcium supplementary material is shown in Table 2. The calcium supplementary material used in this test example is prepared according to the method of Example 1.
[0073] The preparation method of cement-slag-sand autoclaved aerated concrete is as follows:
[0074] S1. Dissolve aluminum powder in water; add the remaining materials in the formula to the blender, add water according to the water material ratio in the ingredients, and continuously stir while heating the slurry to 45-50°C using steam, stir for 2-3 minutes to mix evenly, add warm water (containing dissolved aluminum powder), stir for 40-60 seconds to form a uniform slurry;
[0075] S2. Pour the slurry into the mold, and after pouring is complete, use a steam tamping rod to comb once.
[0076] S3. Push the poured mold into a static curing room with an ambient temperature of 50-60°C, and static curing for 2.5 hours.
[0077] S4. Cut the green body into different specifications of blocks according to actual production needs after static curing.
[0078] S5. After cutting, send it to an autoclave for curing at a steam pressure of 1.2 MPa and a temperature of 185°C for 8 hours.
[0079] The obtained autoclaved aerated concrete blocks were detected according to GB / T11969-2020 "Method for testing the performance of autoclaved aerated concrete", and the results are shown in Table 3.
[0080] Table 3 Cement-slag-sand autoclaved aerated concrete formula and performance
[0081]
[0082] As can be seen from Table 3, after adding calcium supplement material, the dry density of cement-slag-sand autoclaved aerated concrete decreases, and the strength significantly improves, and the performance meets the A3.5 B06 level technical requirements in GB / T11968-2020 "Autoclaved Aerated Concrete Block".
[0083] It should be pointed out that the above examples are only used to illustrate the technical ideas and characteristics of the present application, and the purpose is to enable others to understand the content of the present application and to implement it, and it cannot limit the protection scope of the present application. Any equivalent changes or improvements made according to the spirit of the present application should be covered within the protection scope of the present application.
Claims
1. A calcium supplement material for autoclaved aerated concrete, characterized in that, It consists of the following materials by weight percentage: 5-25% expanded material; 75%-95% lightly calcined dolomitic limestone waste soil.
2. The calcium supplement material for autoclaved aerated concrete according to claim 1, characterized in that, It consists of the following materials by weight percentage: 15-25% expanded material; 75%-85% lightly calcined dolomitic limestone waste soil.
3. The calcium supplement material for autoclaved aerated concrete according to claim 1, characterized in that, It consists of the following materials by weight percentage: 20% expanded material; 80% lightly calcined dolomitic limestone waste soil.
4. The calcium supplement material for autoclaved aerated concrete according to any one of claims 1-3, characterized in that, The expanded material contains 40-60 wt% f-CaO, 5-18 wt% f-CaSO4, ≤12 wt% anhydrous calcium sulfoaluminate, and ≤3.5 wt% periclase.
5. The calcium supplement material for autoclaved aerated concrete according to claim 4, characterized in that, The expanded material contains 53.60 wt% f-CaO, 14.0 wt% f-CaSO4, 8.2 wt% anhydrous calcium sulfoaluminate, and 2.2 wt% periclase.
6. The calcium supplement material for autoclaved aerated concrete according to any one of claims 1-3, characterized in that, The lightly burned dolomitic limestone waste soil is the residue of dolomitic limestone after light burning treatment; the dolomite content of the dolomitic limestone is ≥50wt%.
7. The calcium supplement material for autoclaved aerated concrete according to claim 6, characterized in that, The calcination temperature of lightly burned dolomitic limestone waste soil is 850-950℃, preferably 900℃; Preferably, the content of undecomposed dolomitic limestone in the lightly burned dolomitic limestone waste soil is ≤4wt%, and the residue on an 80μm sieve is ≤18%.
8. The application of the calcium supplement material for autoclaved aerated concrete according to any one of claims 1-7, characterized in that, The application is as a calcareous material in the preparation of autoclaved aerated concrete.
9. The application of the calcium supplement material for autoclaved aerated concrete according to claim 8, characterized in that, The proportion of calcium supplements in the dry mass of autoclaved aerated concrete is greater than 1.0% and less than or equal to 10%.