Alpha hemihydrate gypsum reinforced ultra-lightweight autoclaved aerated concrete and method for preparing the same

Abstract

The application provides alpha hemihydrate gypsum reinforced super-light autoclaved aerated concrete and a preparation method thereof, and relates to the technical field of concrete preparation.The alpha hemihydrate gypsum reinforced super-light autoclaved aerated concrete comprises the following raw materials in parts by weight: 10-50 parts of solid waste gypsum, 10-30 parts of cement, 10-30 parts of carbide slag, 30-60 parts of subway sand, 0.2-1 part of viscosity reducing agent, 0.2-1 part of aluminum powder paste and 0.2-1 part of foam stabilizer.The autoclaved aerated concrete prepared by the application has a density less than 250 kg / m 3 , and the lowest thermal conductivity can reach 0.046 W / (m.k), and shows excellent heat preservation and insulation performance.In addition, the material shows good bonding performance with the finishing mortar, and ensures construction quality and long-term stability.

Description

Technical Field

[0001] This invention relates to the field of concrete preparation technology, and in particular to an α-hemihydrate gypsum-reinforced ultralight autoclaved aerated concrete and its preparation method. Background Technology

[0002] With the rapid development of industries such as phosphorus chemical, coal power, and metallurgy, the discharge of solid waste gypsum has been increasing year by year. The main component of this type of solid waste is calcium sulfate dihydrate (CaSO4·2H2O). Long-term stockpiling not only occupies a large amount of land but also risks leaching heavy metals and other harmful impurities into surface and groundwater systems through rainwater, causing ecological pollution and threatening human health. Furthermore, solid waste gypsum contains renewable calcium sulfate resources, and its improper disposal results in a significant waste of these resources. Therefore, how to achieve efficient resource utilization of solid waste gypsum has become one of the most pressing issues to be addressed in the field of industrial solid waste treatment.

[0003] Autoclaved aerated concrete (AAC) is a lightweight, porous building material made primarily from cement, lime, fly ash, or quartz sand. It boasts advantages such as high strength, thermal insulation, and good fire resistance, and is widely used in building wall structures. However, in traditional processes, the addition of large amounts of gypsum as a modifier often inhibits the foaming process of the slurry, affecting the normal expansion and structural formation of the concrete. This results in coarse, unevenly distributed pores and limited strength development, restricting the efficient utilization of gypsum in AAC. Existing technologies generally improve foaming performance and refine pore structure by adjusting the alkalinity and consistency of the slurry. However, these methods often rely on complex process control or the addition of functional additives, increasing production costs and operational complexity, hindering large-scale application. Furthermore, while these methods can mitigate the adverse effects of gypsum on the foaming process to some extent, they still fall short of achieving uniform and refined pore structures and a significant improvement in product strength.

[0004] Therefore, there is an urgent need to develop an α-hemihydrate gypsum-reinforced ultra-lightweight autoclaved aerated concrete and its preparation method to improve the mechanical properties of ultra-lightweight autoclaved aerated concrete, reduce the environmental burden of solid waste gypsum, promote the transformation of the construction industry towards green and environmentally friendly directions, and provide a new way for the resource utilization and high-value utilization of solid waste gypsum. Summary of the Invention

[0005] In view of this, the present invention proposes an α-hemihydrate gypsum-reinforced ultralight autoclaved aerated concrete and its preparation method, which can not only make efficient use of solid waste gypsum, but also effectively improve the foaming performance and microstructure of autoclaved aerated concrete, thereby achieving the dual goals of solid waste resource utilization and material performance optimization.

[0006] The technical solution of this invention is implemented as follows:

[0007] In a first aspect, the present invention provides an α-hemihydrate gypsum-reinforced ultralight autoclaved aerated concrete, comprising the following raw materials in parts by weight: 10-50 parts solid waste gypsum, 10-30 parts cement, 10-30 parts carbide slag, 30-60 parts iron sand, 0.2-1 parts viscosity reducer, 0.2-1 parts aluminum powder paste, and 0.2-1 parts foam stabilizer.

[0008] Furthermore, the autoclaved aerated concrete also includes water, wherein the water-to-material ratio is 1.0 to 2.0.

[0009] Furthermore, the solid waste gypsum is selected from one or more of phosphogypsum, desulfurization gypsum, and fluorogypsum with a CaSO4·2H2O mass content greater than 90%.

[0010] Furthermore, the cement is selected from one or more of PO 32.5 silicate cement, PO 42.5 silicate cement, and PO 52.5 silicate cement.

[0011] Furthermore, the mass content of SiO2 in the subway sand exceeds 70%.

[0012] Furthermore, the viscosity reducer is a polycarboxylate-based viscosity-reducing water-reducing agent; the foam stabilizer is a mixture of triethanolamine, oleic acid, and water in a mass ratio of 1:3:6.

[0013] Secondly, the present invention relates to a method for preparing the above-mentioned α-hemihydrate gypsum-reinforced ultralight autoclaved aerated concrete, comprising the following steps:

[0014] S1. Prepare the mortar by ball milling solid waste gypsum, subway sand, and carbide slag according to the weight proportions. At the same time, prepare the aluminum powder paste dispersion for later use.

[0015] S2. Mix mortar, cement and viscosity reducer in sequence, stir, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring to obtain slurry;

[0016] S3. Place the slurry into the mold, pre-cur and aerate, then autoclave to obtain autoclaved aerated concrete.

[0017] Firstly, in terms of density control, this invention effectively improves the leaching characteristics of calcium hydroxide (Ca(OH)2) in carbide slag by grinding and homogenizing solid raw materials, forming a uniformly distributed saturated Ca(OH)2 solution in the slurry system. Simultaneously, by controlling the temperature of hot water and steam during the stirring process, a stable temperature field is formed in the slurry. Combined with the synergistic effect of foam stabilizers and viscosity reducers, the gas generation efficiency of aluminum powder and the uniformity of bubble distribution are significantly improved. This achieves refined control of the pore structure and significantly reduces the density and thermal conductivity of autoclaved aerated concrete.

[0018] Secondly, during the pre-curing stage, in addition to the calcium silicate hydrate (CSH) gel produced by cement hydration, some CaSO4·2H2O rapidly reacts with tricalcium aluminate (C3A) in the cement to form ettringite, effectively improving the mechanical properties of autoclaved aerated concrete (AAC). Simultaneously, during the autoclaving stage, calcareous and siliceous raw materials undergo a hydrothermal reaction to generate stable mineral phases such as tobermorite. Furthermore, a large amount of unreacted CaSO4·2H2O dehydrates to form α-type hemihydrate gypsum (α-CaSO4·1 / 2H2O). During subsequent curing, α-CaSO4·1 / 2H2O can further hydrate to generate CaSO4·2H2O, filling the microporous structure of the petal-like tobermorite in the pore walls. This interweaving of the two significantly improves the compressive strength of AAC and reduces the connectivity of the macroscopic pore structure, thereby further reducing the thermal conductivity and improving insulation performance.

[0019] Finally, since the concrete material prepared in this application has a certain amount of CaSO4·2H2O on its surface, when it comes into contact with the plastering mortar, it can react with the aluminum components in the mortar to generate needle-shaped ettringite crystals, which play an interfacial overlapping and anchoring role, thereby significantly improving the bonding performance between aerated concrete and the plastering layer, and improving the durability and construction adaptability of the overall wall system.

[0020] Furthermore, in step S1, the particle size of the mortar is less than 0.075 mm.

[0021] Furthermore, in step S2, after mixing the mortar, cement, and viscosity reducer, the stirring time needs to exceed 3 minutes. Then, add the aluminum powder paste dispersion and foam stabilizer, and continue stirring for 30-40 seconds. Throughout step S2, the temperature needs to be controlled at 40-50℃.

[0022] Furthermore, in step S3, the temperature for pre-curing and gas generation is 40~50℃, and the time is 4~6h.

[0023] Furthermore, after pre-curing and gasification, the gasified embryo can be cut into the required size according to actual application needs.

[0024] Furthermore, the autoclaving temperature is 160~190℃, the pressure is 0.6~1.2 MPa, and the curing time is 6~10h.

[0025] The present invention provides an α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete and its preparation method, which have the following advantages over the prior art:

[0026] (1) The density of the autoclaved aerated concrete prepared by this invention is less than 250 kg / m³. 3With a thermal conductivity as low as 0.046 W / (m·K), this material exhibits excellent thermal insulation performance. Furthermore, it demonstrates good adhesion to plastering mortar, ensuring construction quality and long-term stability.

[0027] (2) The present invention uses a high proportion of solid waste gypsum as one of the raw materials, which not only significantly improves the resource recycling rate and reduces the demand for natural gypsum, but also effectively reduces the production cost and achieves the purpose of green environmental protection, energy conservation and emission reduction. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 The figures show the pore size distribution and sphericity test results of concrete samples prepared in Example 1 and Comparative Example 1 of this invention. In the figures, a is the pore size distribution and sphericity test result of the concrete sample prepared in Example 1, and b is the pore size distribution and sphericity test result of the concrete sample prepared in Comparative Example 1.

[0030] Figure 2 The images show SEM images of concrete samples prepared in Comparative Example 2 and Example 5 of this invention. In the images, a is the SEM image of the concrete sample prepared in Comparative Example 2, and b is the SEM image of the concrete sample prepared in Example 5. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] The present invention will be further described below with reference to specific embodiments. The scope of protection of the present invention is not limited to the following embodiments. The main sources of materials involved in the following examples are shown in Table 1. Unless otherwise specified, they are all conventional commercially available products or raw materials that can be prepared by existing known chemical methods.

[0033] Table 1 Material Source Description

[0034]

[0035] The following are specific embodiments of the present invention.

[0036] Example 1

[0037] This embodiment provides an α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete, comprising 25 parts solid waste gypsum, 17 parts cement, 15 parts carbide slag, 43 parts iron sand, 0.6 parts viscosity reducer, 0.5 parts aluminum powder paste, 0.8 parts foam stabilizer, and a water-to-material ratio of 1.58. This concrete is prepared by the following steps:

[0038] S1. Prepare the mortar by mixing solid waste gypsum, subway sand, and carbide slag according to the stated mass percentage, wet grinding them until the particle size is less than 0.075 mm, and stirring to homogenize them; at the same time, prepare an aluminum powder paste dispersion for later use.

[0039] S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 4 minutes, adjust the temperature to 40℃ by hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 35 seconds to obtain slurry;

[0040] S3. Place the slurry into the mold, pre-cur it at 40℃ for 8 hours to generate gas, and then autoclave it at 190℃ and 1.2MPa for 6 hours to obtain autoclaved aerated concrete.

[0041] The autoclaved aerated concrete prepared in Example 1 was tested using high-resolution three-dimensional X-ray microscopy, such as... Figure 1 As shown in 'a'.

[0042] Comparative Example 1

[0043] This comparative example provides an α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete, comprising 25 parts solid waste gypsum, 17 parts cement, 15 parts carbide slag, 43 parts iron sand, 0.6 parts viscosity reducer, 0.5 parts aluminum powder paste, 0.8 parts foam stabilizer, and a water-to-material ratio of 1.58. This concrete is prepared by the following steps:

[0044] S1. Mix solid waste gypsum, subway sand, and carbide slag according to the stated mass percentage to obtain mortar; at the same time, prepare aluminum powder paste dispersion for later use;

[0045] S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 4 minutes, adjust the temperature to 40℃ by hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 35 seconds to obtain slurry;

[0046] S3. Place the slurry into the mold, pre-cur it at 40℃ for 8 hours to generate gas, and then autoclave it at 190℃ and 1.2MPa for 6 hours to obtain autoclaved aerated concrete.

[0047] The autoclaved aerated concrete prepared in Example 1 was tested using high-resolution three-dimensional X-ray microscopy, such as... Figure 1 As shown in b in the figure.

[0048] Example 2

[0049] This embodiment provides an α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete, comprising 10 parts solid waste gypsum, 20 parts cement, 15 parts carbide slag, 52 parts iron sand, 0.6 parts viscosity reducer, 0.5 parts aluminum powder paste, 0.8 parts foam stabilizer, and a water-to-material ratio of 1.58. This concrete is prepared by the following steps:

[0050] S1. Prepare the mortar by mixing solid waste gypsum, subway sand, and carbide slag according to the stated mass percentage, wet grinding them until the particle size is less than 0.075 mm, and stirring to homogenize them; at the same time, prepare an aluminum powder paste dispersion for later use.

[0051] S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 40℃ by hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 30 seconds to obtain slurry;

[0052] S3. Place the slurry into the mold, pre-cur it at 50℃ for 6 hours to generate gas, and then autoclave it at 160℃ and 0.6MPa for 10 hours to obtain autoclaved aerated concrete.

[0053] Example 3

[0054] This embodiment provides an α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete, comprising 15 parts solid waste gypsum, 19 parts cement, 15 parts carbide slag, 51 parts iron sand, 0.6 parts viscosity reducer, 0.5 parts aluminum powder paste, 0.8 parts foam stabilizer, and a water-to-material ratio of 1.58. This concrete is prepared by the following steps:

[0055] S1. Prepare the mortar by mixing solid waste gypsum, subway sand, and carbide slag according to the stated mass percentage, wet grinding them until the particle size is less than 0.075 mm, and stirring to homogenize them; at the same time, prepare an aluminum powder paste dispersion for later use.

[0056] S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 40℃ by hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 30 seconds to obtain slurry;

[0057] S3. Place the slurry into the mold, pre-cur it at 50℃ for 6 hours to generate gas, and then autoclave it at 160℃ and 0.6MPa for 10 hours to obtain autoclaved aerated concrete.

[0058] Example 4

[0059] This embodiment provides an α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete, comprising 20 parts solid waste gypsum, 18 parts cement, 15 parts carbide slag, 47 parts iron sand, 0.6 parts viscosity reducer, 0.5 parts aluminum powder paste, 0.8 parts foam stabilizer, and a water-to-material ratio of 1.58. This concrete is prepared by the following steps:

[0060] S1. Prepare the mortar by mixing solid waste gypsum, subway sand, and carbide slag according to the stated mass percentage, wet grinding them until the particle size is less than 0.075 mm, and stirring to homogenize them; at the same time, prepare an aluminum powder paste dispersion for later use.

[0061] S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 40℃ by hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 30 seconds to obtain slurry;

[0062] S3. Place the slurry into the mold, pre-cur it at 50℃ for 6 hours to generate gas, and then autoclave it at 160℃ and 0.6MPa for 10 hours to obtain autoclaved aerated concrete.

[0063] Example 5

[0064] This embodiment provides an α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete, comprising 25 parts solid waste gypsum, 17 parts cement, 15 parts carbide slag, 43 parts iron sand, 0.6 parts viscosity reducer, 0.5 parts aluminum powder paste, 0.8 parts foam stabilizer, and a water-to-material ratio of 1.58. This concrete is prepared by the following steps:

[0065] S1. Prepare the mortar by mixing solid waste gypsum, subway sand, and carbide slag according to the stated mass percentage, wet grinding them until the particle size is less than 0.075 mm, and stirring to homogenize them; at the same time, prepare an aluminum powder paste dispersion for later use.

[0066] S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 40℃ by hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 30 seconds to obtain slurry;

[0067] S3. Place the slurry into the mold, pre-cur it at 50℃ for 6 hours to generate gas, and then autoclave it at 160℃ and 0.6MPa for 10 hours to obtain autoclaved aerated concrete.

[0068] Scanning electron microscopy was performed on the autoclaved aerated concrete prepared in Example 5, and the results are as follows: Figure 2 As shown in b in the figure.

[0069] Example 6

[0070] This embodiment provides an α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete, comprising 50 parts solid waste gypsum, 11 parts cement, 9 parts carbide slag, 30 parts iron sand, 0.6 parts viscosity reducer, 0.5 parts aluminum powder paste, 0.8 parts foam stabilizer, and a water-to-material ratio of 1.58. This concrete is prepared by the following steps:

[0071] S1. Prepare the mortar by mixing solid waste gypsum, subway sand, and carbide slag according to the stated mass percentage, wet grinding them until the particle size is less than 0.075 mm, and stirring to homogenize them; at the same time, prepare an aluminum powder paste dispersion for later use.

[0072] S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 40℃ by hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 30 seconds to obtain slurry;

[0073] S3. Place the slurry into the mold, pre-cur it at 50℃ for 6 hours to generate gas, and then autoclave it at 160℃ and 0.6MPa for 10 hours to obtain autoclaved aerated concrete.

[0074] Comparative Example 2

[0075] This embodiment provides an α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete, comprising 5 parts solid waste gypsum, 21 parts cement, 16 parts carbide slag, 58 parts iron sand, 0.6 parts viscosity reducer, 0.5 parts aluminum powder paste, 0.8 parts foam stabilizer, and a water-to-material ratio of 1.58. This concrete is prepared by the following steps:

[0076] S1. Prepare the mortar by mixing solid waste gypsum, subway sand, and carbide slag according to the stated mass percentage, wet grinding them until the particle size is less than 0.075 mm, and stirring to homogenize them; at the same time, prepare an aluminum powder paste dispersion for later use.

[0077] S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 40℃ by hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 30 seconds to obtain slurry;

[0078] S3. Place the slurry into the mold, pre-cur it at 50℃ for 6 hours to generate gas, and then autoclave it at 160℃ and 0.6MPa for 10 hours to obtain autoclaved aerated concrete.

[0079] Scanning electron microscopy was performed on the autoclaved aerated concrete prepared in Comparative Example 2, and the results are as follows: Figure 2 As shown in 'a'.

[0080] Comparative Example 3

[0081] This embodiment provides an α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete, comprising 55 parts solid waste gypsum, 10 parts cement, 8 parts carbide slag, 27 parts iron sand, 0.6 parts viscosity reducer, 0.5 parts aluminum powder paste, 0.8 parts foam stabilizer, and a water-to-material ratio of 1.58. This concrete is prepared by the following steps:

[0082] S1. Prepare the mortar by mixing solid waste gypsum, subway sand, and carbide slag according to the stated mass percentage, wet grinding them until the particle size is less than 0.075 mm, and stirring to homogenize them; at the same time, prepare an aluminum powder paste dispersion for later use.

[0083] S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 40℃ by hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 30 seconds to obtain slurry;

[0084] S3. Place the slurry into the mold, pre-cur it at 50℃ for 6 hours to generate gas, and then autoclave it at 160℃ and 0.6MPa for 10 hours to obtain autoclaved aerated concrete.

[0085] Example 7

[0086] This embodiment provides an α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete, comprising 25 parts solid waste gypsum, 17 parts cement, 15 parts carbide slag, 43 parts iron sand, 0.2 parts viscosity reducer, 0.5 parts aluminum powder paste, 0.8 parts foam stabilizer, and a water-to-material ratio of 1.58. This concrete is prepared by the following steps:

[0087] S1. Prepare the mortar by mixing solid waste gypsum, subway sand, and carbide slag according to the stated mass percentage, wet grinding them until the particle size is less than 0.075 mm, and stirring to homogenize them; at the same time, prepare an aluminum powder paste dispersion for later use.

[0088] S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 50℃ by hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 40 seconds to obtain slurry;

[0089] S3. Place the slurry into the mold, pre-cur it at 50℃ for 4 hours to generate gas, and then autoclave it at 170℃ and 0.8MPa for 9 hours to obtain autoclaved aerated concrete.

[0090] Example 8

[0091] This embodiment provides an α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete, comprising 25 parts solid waste gypsum, 17 parts cement, 15 parts carbide slag, 43 parts iron sand, 0.4 parts viscosity reducer, 0.5 parts aluminum powder paste, 0.8 parts foam stabilizer, and a water-to-material ratio of 1.58. This concrete is prepared by the following steps:

[0092] S1. Prepare the mortar by mixing solid waste gypsum, subway sand, and carbide slag according to the stated mass percentage, wet grinding them until the particle size is less than 0.075 mm, and stirring to homogenize them; at the same time, prepare an aluminum powder paste dispersion for later use.

[0093] S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 50℃ by hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 40 seconds to obtain slurry;

[0094] S3. Place the slurry into the mold, pre-cur it at 50℃ for 4 hours to generate gas, and then autoclave it at 170℃ and 0.8MPa for 9 hours to obtain autoclaved aerated concrete.

[0095] Example 9

[0096] This embodiment provides an α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete, comprising 25 parts solid waste gypsum, 17 parts cement, 15 parts carbide slag, 43 parts iron sand, 0.6 parts viscosity reducer, 0.5 parts aluminum powder paste, 0.8 parts foam stabilizer, and a water-to-material ratio of 1.58. This concrete is prepared by the following steps:

[0097] S1. Prepare the mortar by mixing solid waste gypsum, subway sand, and carbide slag according to the stated mass percentage, wet grinding them until the particle size is less than 0.075 mm, and stirring to homogenize them; at the same time, prepare an aluminum powder paste dispersion for later use.

[0098] S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 50℃ by hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 40 seconds to obtain slurry;

[0099] S3. Place the slurry into the mold, pre-cur it at 50℃ for 4 hours to generate gas, and then autoclave it at 170℃ and 0.8MPa for 9 hours to obtain autoclaved aerated concrete.

[0100] Example 10

[0101] This embodiment provides an α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete, comprising 25 parts solid waste gypsum, 17 parts cement, 15 parts carbide slag, 43 parts iron sand, 0.8 parts viscosity reducer, 0.5 parts aluminum powder paste, 0.8 parts foam stabilizer, and a water-to-material ratio of 1.58. This concrete is prepared by the following steps:

[0102] S1. Prepare the mortar by mixing solid waste gypsum, subway sand, and carbide slag according to the stated mass percentage, wet grinding them until the particle size is less than 0.075 mm, and stirring to homogenize them; at the same time, prepare an aluminum powder paste dispersion for later use.

[0103] S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 50℃ by hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 40 seconds to obtain slurry;

[0104] S3. Place the slurry into the mold, pre-cur it at 50℃ for 4 hours to generate gas, and then autoclave it at 170℃ and 0.8MPa for 9 hours to obtain autoclaved aerated concrete.

[0105] Example 11

[0106] This embodiment provides an α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete, comprising 25 parts solid waste gypsum, 17 parts cement, 15 parts carbide slag, 43 parts iron sand, 1 part viscosity reducer, 0.5 parts aluminum powder paste, 0.8 parts foam stabilizer, and a water-to-material ratio of 1.58. This concrete is prepared by the following steps:

[0107] S1. Prepare the mortar by mixing solid waste gypsum, subway sand, and carbide slag according to the stated mass percentage, wet grinding them until the particle size is less than 0.075 mm, and stirring to homogenize them; at the same time, prepare an aluminum powder paste dispersion for later use.

[0108] S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 50℃ by hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 40 seconds to obtain slurry;

[0109] S3. Place the slurry into the mold, pre-cur it at 50℃ for 4 hours to generate gas, and then autoclave it at 170℃ and 0.8MPa for 9 hours to obtain autoclaved aerated concrete.

[0110] Example 12

[0111] This embodiment provides an α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete, comprising 25 parts solid waste gypsum, 17 parts cement, 15 parts carbide slag, 43 parts iron sand, 0.6 parts viscosity reducer, 0.5 parts aluminum powder paste, 0.2 parts foam stabilizer, and a water-to-material ratio of 1.58. This concrete is prepared by the following steps:

[0112] S1. Prepare the mortar by mixing solid waste gypsum, subway sand, and carbide slag according to the stated mass percentage, wet grinding them until the particle size is less than 0.075 mm, and stirring to homogenize them; at the same time, prepare an aluminum powder paste dispersion for later use.

[0113] S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 50℃ by hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 40 seconds to obtain slurry;

[0114] S3. Place the slurry into the mold, pre-cur it at 50℃ for 4 hours to generate gas, and then autoclave it at 180℃ and 0.9MPa for 8 hours to obtain autoclaved aerated concrete.

[0115] Example 13

[0116] This embodiment provides an α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete, comprising 25 parts solid waste gypsum, 17 parts cement, 15 parts carbide slag, 43 parts iron sand, 0.6 parts viscosity reducer, 0.5 parts aluminum powder paste, 0.4 parts foam stabilizer, and a water-to-material ratio of 1.58. This concrete is prepared by the following steps:

[0117] S1. Prepare the mortar by mixing solid waste gypsum, subway sand, and carbide slag according to the stated mass percentage, wet grinding them until the particle size is less than 0.075 mm, and stirring to homogenize them; at the same time, prepare an aluminum powder paste dispersion for later use.

[0118] S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 50℃ by hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 40 seconds to obtain slurry;

[0119] S3. Place the slurry into the mold, pre-cur it at 50℃ for 4 hours to generate gas, and then autoclave it at 180℃ and 0.9MPa for 8 hours to obtain autoclaved aerated concrete.

[0120] Example 14

[0121] This embodiment provides an α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete, comprising 25 parts solid waste gypsum, 17 parts cement, 15 parts carbide slag, 43 parts iron sand, 0.6 parts viscosity reducer, 0.5 parts aluminum powder paste, 0.6 parts foam stabilizer, and a water-to-material ratio of 1.58. This concrete is prepared by the following steps:

[0122] S1. Prepare the mortar by mixing solid waste gypsum, subway sand, and carbide slag according to the stated mass percentage, wet grinding them until the particle size is less than 0.075 mm, and stirring to homogenize them; at the same time, prepare an aluminum powder paste dispersion for later use.

[0123] S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 50℃ by hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 40 seconds to obtain slurry;

[0124] S3. Place the slurry into the mold, pre-cur it at 50℃ for 4 hours to generate gas, and then autoclave it at 180℃ and 0.9MPa for 8 hours to obtain autoclaved aerated concrete.

[0125] Example 15

[0126] This embodiment provides an α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete, comprising 25 parts solid waste gypsum, 17 parts cement, 15 parts carbide slag, 43 parts iron sand, 0.6 parts viscosity reducer, 0.5 parts aluminum powder paste, 0.8 parts foam stabilizer, and a water-to-material ratio of 1.58. This concrete is prepared by the following steps:

[0127] S1. Prepare the mortar by mixing solid waste gypsum, subway sand, and carbide slag according to the stated mass percentage, wet grinding them until the particle size is less than 0.075 mm, and stirring to homogenize them; at the same time, prepare an aluminum powder paste dispersion for later use.

[0128] S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 50℃ by hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 40 seconds to obtain slurry;

[0129] S3. Place the slurry into the mold, pre-cur it at 50℃ for 4 hours to generate gas, and then autoclave it at 180℃ and 0.9MPa for 8 hours to obtain autoclaved aerated concrete.

[0130] Example 16

[0131] This embodiment provides an α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete, comprising 25 parts solid waste gypsum, 17 parts cement, 15 parts carbide slag, 43 parts iron sand, 0.6 parts viscosity reducer, 0.5 parts aluminum powder paste, 1 part foam stabilizer, and a water-to-material ratio of 1.58. This concrete is prepared by the following steps:

[0132] S1. Prepare the mortar by mixing solid waste gypsum, subway sand, and carbide slag according to the stated mass percentage, wet grinding them until the particle size is less than 0.075 mm, and stirring to homogenize them; at the same time, prepare an aluminum powder paste dispersion for later use.

[0133] S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 50℃ by hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 40 seconds to obtain slurry;

[0134] S3. Place the slurry into the mold, pre-cur it at 50℃ for 4 hours to generate gas, and then autoclave it at 180℃ and 0.9MPa for 8 hours to obtain autoclaved aerated concrete.

[0135] The performance tests of Examples 1-16 and the comparative example were performed as follows. All performance tests were conducted in accordance with the relevant descriptions in GB / T 11969-2020, "Test Methods for Performance of Autoclaved Aerated Concrete". The test results are shown in Table 2. Figure 1 and Figure 2 As shown.

[0136] Table 2 Performance Test Results

[0137]

[0138] In conjunction with Example 1, Comparative Example 1, and Figure 1 As shown in Table 2, the experimental results indicate that when carbide slag, iron sand, and solid waste gypsum were not subjected to wet grinding and homogenization pretreatment, the fluidity of the slurry and the gas generation rate of aluminum powder decreased significantly, while the dry density increased accordingly. Furthermore, the compressive strength of the final product was only 25.58% of that of the pretreated sample. This suggests that untreated raw materials are not conducive to forming a uniform slurry system, thus affecting the foaming process and the development of the green body structure. In addition, from... Figure 1 The comparison of pore structures shown reveals that after wet grinding and homogenization, the sphericity of the pores inside the aerated concrete is significantly improved, and the pore size distribution is more uniform. Statistical analysis of equivalent pore size shows that the most probable equivalent pore size of the untreated sample is 1.6 mm, while the most probable equivalent pore size of the pretreated sample is reduced to 1.2 mm. This indicates that the pretreatment process helps improve the gas generation performance of aluminum powder and achieves refined control of the pore structure, thereby reducing the thermal conductivity and improving the overall material performance.

[0139] In conjunction with Examples 2-6 and Comparative Examples 2-3, Figure 2 As shown in Table 2, the experimental results indicate that when phosphogypsum is added internally, the amount of cement and ground sand needs to be reduced accordingly to maintain a constant calcium-silicon ratio. Theoretically, this would lead to a decrease in the formation of tobermorite, thus negatively impacting the strength of ultra-lightweight autoclaved aerated concrete. However, actual experimental results show that as the gypsum content increased from 5% to 25%, the compressive strength of the samples significantly increased by 133.96%. Meanwhile, Figure 2 Figure 'a' shows the large pores present in the pore walls of the concrete sample prepared in Comparative Example 2, while Figure 2 Figure b shows that in the concrete sample prepared in Example 5, a large amount of gypsum forms α-CaSO4·1 / 2H2O hydration product CaSO4·2H2O during the autoclaving stage. This product fills the microporous structure of petal-like tobermorite on the pore walls and is interspersed with it, thereby significantly improving the compressive strength of the material. After improvement with a viscosity reducer, even with the addition of up to 25% gypsum, the slurry can still maintain a fluidity of over 300 mm, showing good workability. At the same time, the dry density of the ultra-lightweight autoclaved aerated concrete prepared under these conditions does not exceed 250 kg / m³, and the thermal conductivity reaches 0.054 W / (m·K), indicating that it has excellent thermal insulation performance. This shows that the introduction of solid waste gypsum in this invention can not only overcome the negative impact of reduced tobermorite formation, but also effectively improve the mechanical and thermal properties of concrete materials.

[0140] Combining the experimental results of Examples 7-11 and Table 2, it can be seen that with the increase of viscosity reducer dosage, the fluidity and gas evolution rate of the slurry both increase, the dry density gradually decreases, and the compressive strength increases and then decreases. When the viscosity reducer dosage is 0.6% (corresponding to Example 9), compared with Example 7, the fluidity increases by 13.06%, the compressive strength increases by 20.83%, and the thermal conductivity decreases by 5.66%. This indicates that the viscosity reducer lowers the viscosity of the ultra-lightweight autoclaved aerated concrete slurry, making the thickening rate and gas evolution rate of the slurry more matched, improving the gas evolution rate and the uniformity of pore distribution, and reducing the thermal conductivity.

[0141] Combining the experimental results of Examples 12-16 and Table 2, it can be seen that as the dosage of the foam stabilizer increases, the gas evolution rate gradually increases and the dry density gradually decreases. When the dosage of the foam stabilizer is 0.8% (corresponding to Example 15), compared with Example 12, the gas evolution rate increases by 29.48%, the dry density decreases by 17.95%, the compressive strength increases by 21.05%, and the thermal conductivity decreases by 12.28%. This indicates that the foam stabilizer improves the stability of bubbles in the slurry, inhibits the coalescence and escape of bubbles, improves the pore structure of ultra-lightweight autoclaved aerated concrete, thereby increasing its compressive strength and reducing its thermal conductivity.

[0142] 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 principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A type of α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete, characterized in that, The raw materials include the following parts by weight: 15-50 parts solid waste gypsum, 10-30 parts cement, 10-30 parts carbide slag, 30-60 parts iron sand, 0.2-0.8 parts viscosity reducer, 0.2-1 part aluminum powder paste, and 0.2-1 part foam stabilizer. The viscosity reducer is a polycarboxylate-based viscosity-reducing water-reducing agent; Before use, the solid waste gypsum, the subway sand, and the carbide slag need to be blended and wet-milled until the particle size is less than 0.075 mm and then stirred to homogenize.

2. The α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete as described in claim 1, characterized in that, The autoclaved aerated concrete also includes water, wherein... The water-to-material ratio is 1.0-2.

0.

3. The α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete as described in claim 1, characterized in that, The solid waste gypsum is selected from one or more of phosphogypsum, desulfurization gypsum, and fluorogypsum with a CaSO4·H2O mass content greater than 90%.

4. The α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete as described in claim 1, characterized in that, The cement is one or more of PO 32.5 silicate cement, PO 42.5 silicate cement, and PO 52.5 silicate cement.

5. The α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete as described in claim 1, characterized in that, The mass content of SiO2 in the subway sand exceeds 70%.

6. The α-hemihydrate gypsum-reinforced ultralightweight autoclaved aerated concrete as described in claim 1, characterized in that, The viscosity reducer is a polycarboxylate-based viscosity-reducing water-reducing agent; the foam stabilizer is a mixture of triethanolamine, oleic acid and water in a mass ratio of 1:3:

6.

7. A method for preparing α-hemihydrate gypsum-reinforced ultralight autoclaved aerated concrete as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Prepare the mortar by ball milling solid waste gypsum, subway sand, and carbide slag according to the weight proportions. At the same time, prepare the aluminum powder paste dispersion for later use. S2. Mix mortar, cement and viscosity reducer in sequence, stir, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring to obtain slurry; S3. Place the slurry into the mold, pre-cur and aerate, then autoclave to obtain autoclaved aerated concrete.

8. The method for preparing α-hemihydrate gypsum-reinforced ultralight autoclaved aerated concrete as described in claim 7, characterized in that, In step S1, the particle size of the mortar is less than 0.075 mm.

9. The method for preparing α-hemihydrate gypsum-reinforced ultralight autoclaved aerated concrete as described in claim 7, characterized in that, In step S3, the temperature for pre-curing the gas is 40~50℃, and the time is 4~6h.

10. The method for preparing α-hemihydrate gypsum-reinforced ultralight autoclaved aerated concrete as described in claim 9, characterized in that, The autoclaving temperature is 160~190℃, the pressure is 0.6~1.2MPa, and the curing time is 6~10h.

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