Alpha-semi-hydrated gypsum reinforced ultra-light autoclaved aerated concrete and preparation method thereof

Abstract

The invention provides alpha-semi-hydrated gypsum reinforced ultra-light autoclaved aerated concrete and a preparation method thereof, and relates to the technical field of concrete preparation. The alpha-semi-hydrated gypsum reinforced ultra-light autoclaved aerated concrete is prepared from the following raw materials in parts by weight: 10 to 50 parts of solid waste gypsum, 10 to 30 parts of cement, 10 to 30 parts of carbide slag, 30 to 60 parts of subway sand, 0.2 to 1 part of viscosity reducer, 0.2 to 1 part of aluminum powder paste and 0.2 to 1 part of foam stabilizer. The density of the autoclaved aerated concrete prepared by the invention is less than 250 kg / m < 3 >, the minimum heat conductivity coefficient can reach 0.046 W / (m.k), and the autoclaved aerated concrete shows excellent heat insulation performance. In addition, good bonding performance is shown between the material and plastering mortar, and construction quality and long-term stability are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete preparation, and in particular to an alpha hemihydrate gypsum reinforced ultra-lightweight autoclaved aerated concrete and a preparation method thereof. Background Art

[0002] With the rapid development of industries such as phosphorus chemical industry, coal-fired power generation, and metallurgy, the discharge of solid waste gypsum has increased annually. This solid waste, primarily composed of calcium sulfate dihydrate (CaSO4·2H2O), is a waste that, if stored for a long time, not only occupies significant land but also potentially introduces heavy metals and other harmful impurities into surface and groundwater systems through rainwater leaching, polluting the environment and threatening human health. Furthermore, solid waste gypsum contains renewable calcium sulfate, and its inappropriate disposal results in significant waste. Therefore, achieving efficient resource utilization of solid waste gypsum has become a critical and pressing issue in the field of industrial solid waste treatment.

[0003] Autoclaved aerated concrete is a lightweight porous building material made from cement, lime, fly ash or quartz sand as the main raw materials. It has the advantages of light weight, high strength, thermal insulation, and good fire resistance, and is widely used in building wall structures. However, in traditional processes, when gypsum is added in large quantities as a regulator, it often inhibits the gasification process of the slurry, affecting the normal expansion and structure formation of the green body, thereby resulting in a coarse and uneven pore structure of the product, limited strength development, and limiting the efficient use of gypsum in aerated concrete. The existing technology generally improves its foaming performance and refines its pore structure by adjusting the alkalinity and consistency of the slurry. However, the above methods often rely on complex process control or the additional addition of functional additives, which not only increases production costs, but also increases the difficulty of process operation, which is not conducive to large-scale promotion and application. In addition, although these methods can alleviate the adverse effects of gypsum on the foaming process to a certain extent, it is still difficult to achieve uniform refinement of the pore structure and a significant improvement in the strength of the product.

[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, while reducing the burden of solid waste gypsum on the environment, promoting the transformation of the construction industry towards a green and environmentally friendly direction, and providing a new way for the resource 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 ultra-lightweight autoclaved aerated concrete and a preparation method thereof, which can not only efficiently utilize 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 the present invention is achieved as follows: In a first aspect, the present invention provides an α-hemihydrate gypsum reinforced ultra-lightweight autoclaved aerated concrete, comprising 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 reducer, 0.2-1 part of aluminum powder paste, and 0.2-1 part of foam stabilizer.

[0007] Furthermore, the autoclaved aerated concrete also includes water, wherein the water-to-material ratio is 1.0-2.0.

[0008] Furthermore, the solid waste gypsum is selected from one or more of phosphogypsum, desulfurized gypsum, and fluorinated gypsum with a CaSO4·2H2O mass content greater than 90%.

[0009] Furthermore, the cement is selected from one or more of PO 32.5 Portland cement, PO 42.5 Portland cement, and PO 52.5 Portland cement.

[0010] Furthermore, the mass content of SiO2 in the subway sand exceeds 70%.

[0011] Furthermore, the viscosity reducer is a polycarboxylate viscosity reducing water reducer; and the foam stabilizer is a mixture of triethanolamine, oleic acid and water in a mass ratio of 1:3:6.

[0012] In a second aspect, the present invention relates to a method for preparing the above-mentioned α-hemihydrate gypsum reinforced ultra-lightweight autoclaved aerated concrete, comprising the following steps: S1. Mix the solid waste gypsum, subway sand, and carbide slag by ball milling according to the weight ratio to prepare a mortar, and simultaneously prepare an aluminum powder paste dispersion for standby use; S2. Mix mortar, cement and viscosity reducer in sequence, stir, then add aluminum powder paste dispersion and foam stabilizer, continue stirring to obtain slurry; S3. Put the slurry into a mold, pre-curing it to generate gas, and then autoclaving it to obtain autoclaved aerated concrete.

[0013] First, in terms of density control, the present invention effectively improves the dissolution characteristics of calcium hydroxide (Ca(OH)2) in carbide slag by grinding and homogenizing the solid raw materials, forming a uniformly distributed saturated Ca(OH)2 solution in the slurry system; at the same time, by controlling the temperature of hot water and steam during the stirring process, a stable temperature field is formed in the slurry, and combined with the synergistic effect of the foam stabilizer and the viscosity reducer, the gasification efficiency of the aluminum powder and the uniformity of the bubble distribution are significantly improved, thereby realizing the fine control of the pore structure and significantly reducing the density and thermal conductivity of the autoclaved aerated concrete.

[0014] Secondly, during the pre-curing stage, in addition to cement hydration to produce calcium silicate hydrate (CSH) gel, some CaSO4·2H2O rapidly reacts with tricalcium aluminate (CA) in the cement to form ettringite, effectively improving the mechanical properties of autoclaved aerated concrete. Furthermore, during the autoclaving stage, the calcareous and siliceous raw materials undergo a hydrothermal reaction to form stable mineral phases such as tobermorite. Furthermore, a large amount of unreacted CaSO4·2H2O dehydrates to form α-hemihydrate gypsum (α-CaSO4·1 / 2H2O). During subsequent curing, this α-CaSO4·1 / 2H2O further hydrates to form CaSO4·2H2O, filling the micropores of the petal-shaped tobermorite on the pore walls. The intertwining of the two significantly enhances the compressive strength of the autoclaved aerated concrete and reduces the connectivity of the macropore structure, further lowering thermal conductivity and improving thermal insulation performance.

[0015] Finally, since a certain amount of CaSO4·2H2O exists on the surface of the concrete material prepared in this application, when it comes into contact with the plaster mortar, it can react with the aluminum component in the mortar to form needle-shaped ettringite crystals, which play an interface overlapping and anchoring role, thereby significantly improving the bonding performance between the aerated concrete and the plaster layer, and improving the durability and construction adaptability of the overall wall system.

[0016] Furthermore, in step S1, the particle size of the mortar is less than 0.075 mm.

[0017] Furthermore, in step S2, after mixing the mortar, cement, and viscosity reducer, the stirring time should be more than 3 minutes, and then the aluminum powder paste dispersion and foam stabilizer are added, and stirring is continued for 30-40 seconds. During the entire step S2 process, the temperature should be controlled at 40-50°C.

[0018] Furthermore, in step S3, the temperature of the pre-curing gasification is 40-50° C. and the time is 4-6 hours.

[0019] Furthermore, after pre-curing and gasification, the gasified embryo body can be cut into required sizes according to actual application needs.

[0020] Furthermore, the temperature of the autoclave curing is 160-190° C., the pressure is 0.6-1.2 MPa, and the curing time is 6-10 hours.

[0021] The α-hemihydrate gypsum reinforced ultra-lightweight autoclaved aerated concrete and its preparation method of the present invention have the following beneficial effects compared with the prior art: (1) The density of the autoclaved aerated concrete prepared by the present invention is less than 250 kg / m 3The thermal conductivity can reach as low as 0.046W / (m·k), demonstrating excellent thermal insulation performance. In addition, the material exhibits good bonding properties with the plaster mortar, ensuring construction quality and long-term stability.

[0022] (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 production costs, achieving the goals of green environmental protection, energy conservation and emission reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 The figures are the pore size distribution and sphericity test graphs of the concrete samples prepared in Example 1 and Comparative Example 1 of the present invention. In the figure, a is the pore size distribution and sphericity test graph of the concrete sample prepared in Example 1, and b is the pore size distribution and sphericity test graph of the concrete sample prepared in Comparative Example 1; Figure 2 These are SEM images of concrete samples prepared in Comparative Example 2 and Example 5 of the present invention. In the figure, 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 DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] The present invention will be further described below with reference to specific examples, but the scope of protection of the present invention is not limited by the following examples. The sources of the materials mainly involved in the following examples are shown in Table 1. Unless otherwise specified, they are all conventional commercial products or raw materials that can be prepared by existing known chemical methods.

[0027] Table 1 Material source description

[0028] The following are specific embodiments of the present invention.

[0029] Example 1 This embodiment provides an α-hemihydrate gypsum-reinforced ultra-lightweight autoclaved aerated concrete comprising 25 parts of solid waste gypsum, 17 parts of cement, 15 parts of carbide slag, 43 parts of subway sand, 0.6 parts of a viscosity reducer, 0.5 parts of aluminum paste, 0.8 parts of a foam stabilizer, and a water-to-cement ratio of 1.58. The concrete is prepared by the following steps: S1. Mix solid waste gypsum, subway sand, and carbide slag according to the mass percentage, wet-grind them until the particle size is less than 0.075 mm, and stir and homogenize them to obtain a mortar; at the same time, prepare an aluminum powder paste dispersion for standby use; S2. Mix mortar, PO 52.5 ordinary Portland cement, and viscosity reducer in sequence, stir for 4 minutes, adjust the temperature to 40°C with hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 35 seconds to obtain a slurry; S3. Place the slurry into a mold, pre-curing it at 40°C for 8 hours to generate gas, and then autoclave curing it at 190°C and 1.2 MPa for 6 hours to obtain autoclaved aerated concrete.

[0030] The autoclaved aerated concrete prepared in Example 1 was tested using high-resolution three-dimensional X-ray microscopy. Figure 1 As shown in a.

[0031] Comparative Example 1 This comparative example provides an α-hemihydrate gypsum-reinforced ultra-lightweight autoclaved aerated concrete comprising 25 parts of solid waste gypsum, 17 parts of cement, 15 parts of carbide slag, 43 parts of subway sand, 0.6 parts of a viscosity reducer, 0.5 parts of aluminum paste, 0.8 parts of a foam stabilizer, and a water-to-material ratio of 1.58. The concrete is prepared by the following steps: S1, mixing solid waste gypsum, subway sand, and calcium carbide slag according to the mass percentage to obtain mortar; and simultaneously preparing an aluminum powder paste dispersion for standby use; S2. Mix mortar, PO 52.5 ordinary Portland cement, and viscosity reducer in sequence, stir for 4 minutes, adjust the temperature to 40°C with hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 35 seconds to obtain a slurry; S3. Place the slurry into a mold, pre-curing it at 40°C for 8 hours to generate gas, and then autoclave curing it at 190°C and 1.2 MPa for 6 hours to obtain autoclaved aerated concrete.

[0032] The autoclaved aerated concrete prepared in Example 1 was tested using high-resolution three-dimensional X-ray microscopy. Figure 1 As shown in b.

[0033] Example 2 This embodiment provides an α-hemihydrate gypsum-reinforced ultra-lightweight autoclaved aerated concrete comprising 10 parts of solid waste gypsum, 20 parts of cement, 15 parts of carbide slag, 52 parts of subway sand, 0.6 parts of a viscosity reducer, 0.5 parts of aluminum paste, 0.8 parts of a foam stabilizer, and a water-to-cement ratio of 1.58. The concrete is prepared by the following steps: S1. Mix solid waste gypsum, subway sand, and carbide slag according to the mass percentage, wet-grind them until the particle size is less than 0.075 mm, and stir and homogenize them to obtain a mortar; at the same time, prepare an aluminum powder paste dispersion for standby use; S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 40°C with hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 30 seconds to obtain slurry; S3. Place the slurry into a mold, pre-curing it at 50°C for 6 hours to generate gas, and then autoclave curing it at 160°C and 0.6 MPa for 10 hours to obtain autoclaved aerated concrete.

[0034] Example 3 This embodiment provides an α-hemihydrate gypsum-reinforced ultra-lightweight autoclaved aerated concrete comprising 15 parts of solid waste gypsum, 19 parts of cement, 15 parts of carbide slag, 51 parts of subway sand, 0.6 parts of a viscosity reducer, 0.5 parts of aluminum paste, 0.8 parts of a foam stabilizer, and a water-to-cement ratio of 1.58. The concrete is prepared by the following steps: S1. Mix solid waste gypsum, subway sand, and carbide slag according to the mass percentage, wet-grind them until the particle size is less than 0.075 mm, and stir and homogenize them to obtain a mortar; at the same time, prepare an aluminum powder paste dispersion for standby use; S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 40°C with hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 30 seconds to obtain slurry; S3. Place the slurry into a mold, pre-curing it at 50°C for 6 hours to generate gas, and then autoclave curing it at 160°C and 0.6 MPa for 10 hours to obtain autoclaved aerated concrete.

[0035] Example 4 This embodiment provides an α-hemihydrate gypsum-reinforced ultra-lightweight autoclaved aerated concrete comprising 20 parts of solid waste gypsum, 18 parts of cement, 15 parts of carbide slag, 47 parts of subway sand, 0.6 parts of a viscosity reducer, 0.5 parts of aluminum paste, 0.8 parts of a foam stabilizer, and a water-to-cement ratio of 1.58. The concrete is prepared by the following steps: S1. Mix solid waste gypsum, subway sand, and carbide slag according to the mass percentage, wet-grind them until the particle size is less than 0.075 mm, and stir and homogenize them to obtain a mortar; at the same time, prepare an aluminum powder paste dispersion for standby use; S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 40°C with hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 30 seconds to obtain slurry; S3. Place the slurry into a mold, pre-curing it at 50°C for 6 hours to generate gas, and then autoclave curing it at 160°C and 0.6 MPa for 10 hours to obtain autoclaved aerated concrete.

[0036] Example 5 This embodiment provides an α-hemihydrate gypsum-reinforced ultra-lightweight autoclaved aerated concrete comprising 25 parts of solid waste gypsum, 17 parts of cement, 15 parts of carbide slag, 43 parts of subway sand, 0.6 parts of a viscosity reducer, 0.5 parts of aluminum paste, 0.8 parts of a foam stabilizer, and a water-to-cement ratio of 1.58. The concrete is prepared by the following steps: S1. Mix solid waste gypsum, subway sand, and carbide slag according to the mass percentage, wet-grind them until the particle size is less than 0.075 mm, and stir and homogenize them to obtain a mortar; at the same time, prepare an aluminum powder paste dispersion for standby use; S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 40°C with hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 30 seconds to obtain slurry; S3. Place the slurry into a mold, pre-curing it at 50°C for 6 hours to generate gas, and then autoclave curing it at 160°C and 0.6 MPa for 10 hours to obtain autoclaved aerated concrete.

[0037] The autoclaved aerated concrete prepared in Example 5 was subjected to scanning electron microscopy, and the results were as follows: Figure 2 As shown in b.

[0038] Example 6 This embodiment provides an α-hemihydrate gypsum-reinforced ultra-lightweight autoclaved aerated concrete comprising 50 parts of solid waste gypsum, 11 parts of cement, 9 parts of carbide slag, 30 parts of subway sand, 0.6 parts of a viscosity reducer, 0.5 parts of aluminum paste, 0.8 parts of a foam stabilizer, and a water-to-cement ratio of 1.58. The concrete is prepared by the following steps: S1. Mix solid waste gypsum, subway sand, and carbide slag according to the mass percentage, wet-grind them until the particle size is less than 0.075 mm, and stir and homogenize them to obtain a mortar; at the same time, prepare an aluminum powder paste dispersion for standby use; S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 40°C with hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 30 seconds to obtain slurry; S3. Place the slurry into a mold, pre-curing it at 50°C for 6 hours to generate gas, and then autoclave curing it at 160°C and 0.6 MPa for 10 hours to obtain autoclaved aerated concrete.

[0039] Comparative Example 2 This embodiment provides an α-hemihydrate gypsum-reinforced ultra-lightweight autoclaved aerated concrete comprising 5 parts of solid waste gypsum, 21 parts of cement, 16 parts of carbide slag, 58 parts of subway sand, 0.6 parts of a viscosity reducer, 0.5 parts of aluminum paste, 0.8 parts of a foam stabilizer, and a water-to-cement ratio of 1.58. The concrete is prepared by the following steps: S1. Mix solid waste gypsum, subway sand, and carbide slag according to the mass percentage, wet-grind them until the particle size is less than 0.075 mm, and stir and homogenize them to obtain a mortar; at the same time, prepare an aluminum powder paste dispersion for standby use; S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 40°C with hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 30 seconds to obtain slurry; S3. Place the slurry into a mold, pre-curing it at 50°C for 6 hours to generate gas, and then autoclave curing it at 160°C and 0.6 MPa for 10 hours to obtain autoclaved aerated concrete.

[0040] The autoclaved aerated concrete prepared in Comparative Example 2 was subjected to scanning electron microscopy, and the results were as follows: Figure 2 As shown in a.

[0041] Comparative Example 3 This embodiment provides an α-hemihydrate gypsum-reinforced ultra-lightweight autoclaved aerated concrete comprising 55 parts of solid waste gypsum, 10 parts of cement, 8 parts of carbide slag, 27 parts of subway sand, 0.6 parts of a viscosity reducer, 0.5 parts of aluminum paste, 0.8 parts of a foam stabilizer, and a water-to-cement ratio of 1.58. The concrete is prepared by the following steps: S1. Mix solid waste gypsum, subway sand, and carbide slag according to the mass percentage, wet-grind them until the particle size is less than 0.075 mm, and stir and homogenize them to obtain a mortar; at the same time, prepare an aluminum powder paste dispersion for standby use; S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 40°C with hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 30 seconds to obtain slurry; S3. Place the slurry into a mold, pre-curing it at 50°C for 6 hours to generate gas, and then autoclave curing it at 160°C and 0.6 MPa for 10 hours to obtain autoclaved aerated concrete.

[0042] Example 7 This embodiment provides an α-hemihydrate gypsum-reinforced ultra-lightweight autoclaved aerated concrete comprising 25 parts of solid waste gypsum, 17 parts of cement, 15 parts of carbide slag, 43 parts of subway sand, 0.2 parts of a viscosity reducer, 0.5 parts of aluminum paste, 0.8 parts of a foam stabilizer, and a water-to-cement ratio of 1.58. The concrete is prepared by the following steps: S1. Mix solid waste gypsum, subway sand, and carbide slag according to the mass percentage, wet-grind them until the particle size is less than 0.075 mm, and stir and homogenize them to obtain a mortar; at the same time, prepare an aluminum powder paste dispersion for standby use; S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 50°C with hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 40 seconds to obtain slurry; S3. Place the slurry into a mold, pre-curing it at 50°C for 4 hours to generate gas, and then autoclave curing it at 170°C and 0.8 MPa for 9 hours to obtain autoclaved aerated concrete.

[0043] Example 8 This embodiment provides an α-hemihydrate gypsum-reinforced ultra-lightweight autoclaved aerated concrete comprising 25 parts of solid waste gypsum, 17 parts of cement, 15 parts of carbide slag, 43 parts of subway sand, 0.4 parts of a viscosity reducer, 0.5 parts of aluminum paste, 0.8 parts of a foam stabilizer, and a water-to-cement ratio of 1.58. The concrete is prepared by the following steps: S1. Mix solid waste gypsum, subway sand, and carbide slag according to the mass percentage, wet-grind them until the particle size is less than 0.075 mm, and stir and homogenize them to obtain a mortar; at the same time, prepare an aluminum powder paste dispersion for standby use; S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 50°C with hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 40 seconds to obtain slurry; S3. Place the slurry into a mold, pre-curing it at 50°C for 4 hours to generate gas, and then autoclave curing it at 170°C and 0.8 MPa for 9 hours to obtain autoclaved aerated concrete.

[0044] Example 9 This embodiment provides an α-hemihydrate gypsum-reinforced ultra-lightweight autoclaved aerated concrete comprising 25 parts of solid waste gypsum, 17 parts of cement, 15 parts of carbide slag, 43 parts of subway sand, 0.6 parts of a viscosity reducer, 0.5 parts of aluminum paste, 0.8 parts of a foam stabilizer, and a water-to-cement ratio of 1.58. The concrete is prepared by the following steps: S1. Mix solid waste gypsum, subway sand, and carbide slag according to the mass percentage, wet-grind them until the particle size is less than 0.075 mm, and stir and homogenize them to obtain a mortar; at the same time, prepare an aluminum powder paste dispersion for standby use; S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 50°C with hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 40 seconds to obtain slurry; S3. Place the slurry into a mold, pre-curing it at 50°C for 4 hours to generate gas, and then autoclave curing it at 170°C and 0.8 MPa for 9 hours to obtain autoclaved aerated concrete.

[0045] Example 10 This embodiment provides an α-hemihydrate gypsum-reinforced ultra-lightweight autoclaved aerated concrete comprising 25 parts of solid waste gypsum, 17 parts of cement, 15 parts of carbide slag, 43 parts of subway sand, 0.8 parts of a viscosity reducer, 0.5 parts of aluminum paste, 0.8 parts of a foam stabilizer, and a water-to-cement ratio of 1.58. The concrete is prepared by the following steps: S1. Mix solid waste gypsum, subway sand, and carbide slag according to the mass percentage, wet-grind them until the particle size is less than 0.075 mm, and stir and homogenize them to obtain a mortar; at the same time, prepare an aluminum powder paste dispersion for standby use; S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 50°C with hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 40 seconds to obtain slurry; S3. Place the slurry into a mold, pre-curing it at 50°C for 4 hours to generate gas, and then autoclave curing it at 170°C and 0.8 MPa for 9 hours to obtain autoclaved aerated concrete.

[0046] Example 11 This embodiment provides an α-hemihydrate gypsum-reinforced ultra-lightweight autoclaved aerated concrete comprising 25 parts of solid waste gypsum, 17 parts of cement, 15 parts of carbide slag, 43 parts of subway sand, 1 part of a viscosity reducer, 0.5 parts of aluminum paste, 0.8 parts of a foam stabilizer, and a water-to-cement ratio of 1.58. The concrete is prepared by the following steps: S1. Mix solid waste gypsum, subway sand, and carbide slag according to the mass percentage, wet-grind them until the particle size is less than 0.075 mm, and stir and homogenize them to obtain a mortar; at the same time, prepare an aluminum powder paste dispersion for standby use; S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 50°C with hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 40 seconds to obtain slurry; S3. Place the slurry into a mold, pre-curing it at 50°C for 4 hours to generate gas, and then autoclave curing it at 170°C and 0.8 MPa for 9 hours to obtain autoclaved aerated concrete.

[0047] Example 12 This embodiment provides an α-hemihydrate gypsum-reinforced ultra-lightweight autoclaved aerated concrete comprising 25 parts of solid waste gypsum, 17 parts of cement, 15 parts of carbide slag, 43 parts of subway sand, 0.6 parts of a viscosity reducer, 0.5 parts of aluminum paste, 0.2 parts of a foam stabilizer, and a water-to-cement ratio of 1.58. The concrete is prepared by the following steps: S1. Mix solid waste gypsum, subway sand, and carbide slag according to the mass percentage, wet-grind them until the particle size is less than 0.075 mm, and stir and homogenize them to obtain a mortar; at the same time, prepare an aluminum powder paste dispersion for standby use; S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 50°C with hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 40 seconds to obtain slurry; S3. Place the slurry into a mold, pre-curing it at 50°C for 4 hours to generate gas, and then autoclave curing it at 180°C and 0.9 MPa for 8 hours to obtain autoclaved aerated concrete.

[0048] Example 13 This embodiment provides an α-hemihydrate gypsum-reinforced ultra-lightweight autoclaved aerated concrete comprising 25 parts of solid waste gypsum, 17 parts of cement, 15 parts of carbide slag, 43 parts of subway sand, 0.6 parts of a viscosity reducer, 0.5 parts of aluminum paste, 0.4 parts of a foam stabilizer, and a water-to-cement ratio of 1.58. The concrete is prepared by the following steps: S1. Mix solid waste gypsum, subway sand, and carbide slag according to the mass percentage, wet-grind them until the particle size is less than 0.075 mm, and stir and homogenize them to obtain a mortar; at the same time, prepare an aluminum powder paste dispersion for standby use; S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 50°C with hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 40 seconds to obtain slurry; S3. Place the slurry into a mold, pre-curing it at 50°C for 4 hours to generate gas, and then autoclave curing it at 180°C and 0.9 MPa for 8 hours to obtain autoclaved aerated concrete.

[0049] Example 14 This embodiment provides an α-hemihydrate gypsum-reinforced ultra-lightweight autoclaved aerated concrete comprising 25 parts of solid waste gypsum, 17 parts of cement, 15 parts of carbide slag, 43 parts of subway sand, 0.6 parts of a viscosity reducer, 0.5 parts of aluminum paste, 0.6 parts of a foam stabilizer, and a water-to-cement ratio of 1.58. The concrete is prepared by the following steps: S1. Mix solid waste gypsum, subway sand, and carbide slag according to the mass percentage, wet-grind them until the particle size is less than 0.075 mm, and stir and homogenize them to obtain a mortar; at the same time, prepare an aluminum powder paste dispersion for standby use; S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 50°C with hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 40 seconds to obtain slurry; S3. Place the slurry into a mold, pre-curing it at 50°C for 4 hours to generate gas, and then autoclave curing it at 180°C and 0.9 MPa for 8 hours to obtain autoclaved aerated concrete.

[0050] Example 15 This embodiment provides an α-hemihydrate gypsum-reinforced ultra-lightweight autoclaved aerated concrete comprising 25 parts of solid waste gypsum, 17 parts of cement, 15 parts of carbide slag, 43 parts of subway sand, 0.6 parts of a viscosity reducer, 0.5 parts of aluminum paste, 0.8 parts of a foam stabilizer, and a water-to-cement ratio of 1.58. The concrete is prepared by the following steps: S1. Mix solid waste gypsum, subway sand, and carbide slag according to the mass percentage, wet-grind them until the particle size is less than 0.075 mm, and stir and homogenize them to obtain a mortar; at the same time, prepare an aluminum powder paste dispersion for standby use; S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 50°C with hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 40 seconds to obtain slurry; S3. Place the slurry into a mold, pre-curing it at 50°C for 4 hours to generate gas, and then autoclave curing it at 180°C and 0.9 MPa for 8 hours to obtain autoclaved aerated concrete.

[0051] Example 16 This embodiment provides an α-hemihydrate gypsum-reinforced ultra-lightweight autoclaved aerated concrete comprising 25 parts of solid waste gypsum, 17 parts of cement, 15 parts of carbide slag, 43 parts of subway sand, 0.6 parts of a viscosity reducer, 0.5 parts of aluminum paste, 1 part of a foam stabilizer, and a water-to-cement ratio of 1.58. The concrete is prepared by the following steps: S1. Mix solid waste gypsum, subway sand, and carbide slag according to the mass percentage, wet-grind them until the particle size is less than 0.075 mm, and stir and homogenize them to obtain a mortar; at the same time, prepare an aluminum powder paste dispersion for standby use; S2. Mix mortar, PO 52.5 ordinary Portland cement and viscosity reducer in sequence, stir for 5 minutes, adjust the temperature to 50°C with hot water and steam, then add aluminum powder paste dispersion and foam stabilizer, and continue stirring for 40 seconds to obtain slurry; S3. Place the slurry into a mold, pre-curing it at 50°C for 4 hours to generate gas, and then autoclave curing it at 180°C and 0.9 MPa for 8 hours to obtain autoclaved aerated concrete.

[0052] The following performance tests were performed on the above Examples 1 to 16 and the comparative example. All performance tests were conducted with reference to the relevant records in the "Test Methods for Performance of Autoclaved Aerated Concrete" GB / T 11969-2020. The test results are shown in Table 2. Figure 1 and Figure 2 shown.

[0053] Table 2 Performance test results

[0054] Combined with Example 1, Comparative Example 1 and Figure 1 The experimental results shown in Table 2 show that when carbide slag, subway sand and solid waste gypsum are not pre-treated by wet grinding and homogenization, the fluidity of the slurry and the gas evolution rate of aluminum powder are significantly reduced, the dry density is correspondingly increased, and the compressive strength of the final product is only 25.58% of that of the pre-treated sample. This shows that the raw materials without pre-treatment are not conducive to the formation of a uniform slurry system, which in turn affects the foaming process and the development of the green body structure. In addition, Figure 1 A comparison of the pore structures shown in the figure shows that after wet grinding and homogenization, the sphericity of the pores within the aerated concrete is significantly improved, and the pore size distribution is more uniform. Statistical analysis of equivalent pore diameters reveals that the most probable equivalent pore diameter of the untreated sample is 1.6 mm, while that of the pretreated sample is reduced to 1.2 mm. This indicates that the pretreatment process helps improve the gassing properties of aluminum powder and achieves refined control of the pore structure, thereby reducing thermal conductivity and improving the overall performance of the material.

[0055] Combined with Examples 2 to 6, Comparative Examples 2 to 3, Figure 2 The experimental results shown in Table 2 show that when phosphogypsum is added as an internal admixture, in order to maintain the same calcium-silicon ratio, the amount of cement and subway sand needs to be reduced accordingly. This theoretically leads to a decrease in the amount of tobermorite generated, which in turn has an adverse effect on the strength of ultra-lightweight autoclaved aerated concrete. However, the actual experimental results show that as the gypsum content increases from 5% to 25%, the compressive strength of the sample increases significantly by 133.96%. At the same time, Figure 2 a in FIG shows the larger pores in the pore wall of the concrete sample prepared in Comparative Example 2, while Figure 2Figure b shows that in the concrete sample prepared in Example 5, a large amount of gypsum is added to form the α-CaSO4·1 / 2H2O hydration product CaSO4·2H2O during the autoclaving stage. This product fills the microporous structure of the petal-shaped tobermorite on the pore wall and is staggered with it, thereby greatly improving the compressive strength of the material. After the application of the viscosity reducer, even with the addition of up to 25% gypsum, the slurry can still maintain a fluidity of more than 300mm, showing good working performance. 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 coefficient reaches 0.054 W / (m·K), indicating that it has excellent thermal insulation properties. This shows that after the introduction of solid waste gypsum in the present invention, it can not only overcome the negative impact caused by the reduction in the amount of tobermorite generated, but also effectively improve the mechanical properties and thermal properties of the concrete material.

[0056] Combining the experimental results of Examples 7-11 and Table 2, it can be seen that as the viscosity reducer dosage increases, the fluidity and gas evolution rate of the slurry increase, the dry density gradually decreases, and the compressive strength increases with the addition of the additive. At a viscosity reducer dosage of 0.6% (corresponding to Example 9), compared to Example 7, the fluidity increased by 13.06%, the compressive strength increased by 20.83%, and the thermal conductivity decreased by 5.66%. This demonstrates that the viscosity reducer reduces the viscosity of the ultra-lightweight autoclaved aerated concrete slurry, resulting in a better match between the thickening rate and gas evolution rate of the slurry, improving the gas evolution rate and pore distribution uniformity, and reducing the thermal conductivity.

[0057] Combining the experimental results of Examples 12-16 and Table 2, we can see that as the foam stabilizer dosage increases, the gas evolution rate gradually increases and the dry density gradually decreases. At a foam stabilizer dosage of 0.8% (corresponding to Example 15), compared to Example 12, the gas evolution rate increased by 29.48%, the dry density decreased by 17.95%, the compressive strength increased by 21.05%, and the thermal conductivity decreased by 12.28%. This demonstrates that the foam stabilizer enhances the stability of bubbles in the slurry, inhibits bubble coalescence, growth, and escape, and improves the pore structure of the ultra-lightweight autoclaved aerated concrete, thereby increasing its compressive strength and reducing its thermal conductivity.

[0058] 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 in the scope of protection of the present invention.

Claims

1. An α-hemihydrate gypsum reinforced ultra-light autoclaved aerated concrete, characterized in that: The method 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 reducer, 0.2-1 part of aluminum powder paste, and 0.2-1 part of foam stabilizer.

2. The α-hemihydrate gypsum reinforced ultra-lightweight autoclaved aerated concrete according to 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 ultra-lightweight autoclaved aerated concrete according to claim 1, characterized in that: The solid waste gypsum is selected from one or more of phosphogypsum, desulfurized gypsum, and fluorinated gypsum with a CaSO4·2H2O mass content greater than 90%.

4. The α-hemihydrate gypsum reinforced ultra-light autoclaved aerated concrete according to claim 1, characterized in that: The cement is selected from one or more of PO 32.5 Portland cement, PO 42.5 Portland cement, and PO 52.5 Portland cement.

5. The α-hemihydrate gypsum reinforced ultra-lightweight autoclaved aerated concrete according to claim 1, wherein: The mass content of SiO2 in the subway sand exceeds 70%.

6. The α-hemihydrate gypsum reinforced ultra-lightweight autoclaved aerated concrete according to claim 1, characterized in that: The viscosity reducer is a polycarboxylate viscosity reducing water reducer; and 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 the α-hemihydrate gypsum reinforced ultra-light autoclaved aerated concrete according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Mix the solid waste gypsum, subway sand, and carbide slag by ball milling according to the weight ratio to prepare a mortar, and simultaneously prepare an aluminum powder paste dispersion for standby use; S2. Mix mortar, cement and viscosity reducer in sequence, stir, then add aluminum powder paste dispersion and foam stabilizer, continue stirring to obtain slurry; S3. Put the slurry into a mold, pre-curing it to generate gas, and then autoclaving it to obtain autoclaved aerated concrete.

8. The method for preparing α-hemihydrate gypsum reinforced ultra-light autoclaved aerated concrete according to claim 7, wherein: In step S1, the particle size of the mortar is less than 0.075 mm.

9. The method for preparing α-hemihydrate gypsum reinforced ultra-light autoclaved aerated concrete according to claim 7, wherein: In step S3, the temperature of the pre-curing gas is 40-50° C. and the time is 4-6 hours.

10. The method for preparing α-hemihydrate gypsum reinforced ultra-light autoclaved aerated concrete according to claim 9, wherein: The temperature of the autoclave curing is 160-190° C., the pressure is 0.6-1.2 MPa, and the curing time is 6-10 hours.

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