Soundproof fireproof aerated block concrete block and preparation method thereof

Abstract

The present application belongs to the technical field of concrete building materials, and particularly relates to a soundproof fireproof aerated block concrete block and a preparation method thereof. The block is prepared from the following raw materials in parts by weight: 36-44 parts of quartz sand, 12-17 parts of fly ash, 15-19 parts of ordinary Portland cement, 9-13 parts of quicklime, 2.5-3.8 parts of desulfurization gypsum, 4-7 parts of barite powder, 2.5-4.5 parts of expanded vermiculite powder, 1.2-2.5 parts of sepiolite powder, 1-1.8 parts of silica fume, 0.25-0.5 parts of basalt short fiber, 0.7-1.2 parts of sodium silicate solution, 0.08-0.13 parts of aluminum paste and 58-64 parts of mixing water. The present application adjusts the raw material composition and the gas evolution and pore forming process on the basis of the original light weight, heat preservation and non-combustible characteristics of the aerated concrete block, and adds a proper amount of soundproof fireproof functional material, so that the block has good soundproof effect and high temperature stability.

Description

Technical Field

[0001] This invention belongs to the field of concrete building materials technology, specifically relating to a sound-insulating and fire-resistant aerated concrete block and its preparation method. Background Technology

[0002] Autoclaved aerated concrete (AAC) blocks are a commonly used building wall material. They are typically made from siliceous and calcareous materials as the main raw materials, combined with foaming agents and modifiers, and manufactured through processes such as batching and mixing, pouring for foaming, static curing, cutting and shaping, and autoclaving. Due to their highly porous internal structure, AAC blocks offer advantages such as light weight, good thermal insulation, easy construction, uniform dimensions, and good non-combustibility, and are widely used in interior partitions, exterior walls, and infill walls. With increasing demands for building performance, wall materials, in addition to meeting basic strength and construction requirements, also need to consider sound insulation, fire resistance, thermal insulation, and long-term stability. While AAC blocks offer significant advantages in terms of lightweight and thermal insulation, their relatively low density and high porosity result in a relatively small mass per unit area, leading to some shortcomings in airborne sound insulation. Especially when the internal pore size distribution of the blocks is uneven, the proportion of interconnected pores is high, or the mortar joints, grooves, and wall connections are not dense enough, sound waves can easily propagate through the pore structure, microcracks, or interface defects, thus affecting the overall sound insulation effect of the wall.

[0003] In existing technologies, methods to improve the sound insulation performance of aerated concrete blocks typically include increasing block density, adding mineral fillers, composite sound insulation layers, or incorporating damping materials. However, simply increasing block density, while beneficial for improving wall surface density, can easily diminish the advantages of aerated concrete blocks in terms of lightweight, thermal insulation, and ease of construction. Adding an external sound insulation layer increases the complexity of the wall structure and construction costs. Furthermore, adding excessive amounts of organic damping materials or polymer-modified materials may adversely affect the non-combustible properties, high-temperature stability, and smoke safety of the blocks, failing to meet fire safety requirements for building wall materials. In addition, the pore structure of aerated concrete blocks significantly impacts their sound insulation, fire resistance, and operational stability. If the pore structure is too large or has strong connectivity, it will not only reduce the sound insulation effect of the material, but may also lead to increased water absorption, increased shrinkage deformation and decreased local strength. If the pore wall strength is insufficient or there are many micro-cracks inside the block, problems such as edge and corner damage, wall cracking or plaster layer hollowing are likely to occur during handling, construction and long-term service, which will affect the continuous performance of the wall's sound insulation and fireproofing effects. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a sound-insulating and fire-resistant aerated concrete block and its preparation method. This addresses the problems of insufficient sound insulation performance in existing aerated concrete blocks due to their low density and high porosity, and the tendency to weaken the block's lightweight, thermal insulation, and fire resistance when improving sound insulation by increasing density or adding organic modifiers. The present invention, based on the original lightweight, thermal insulation, and non-combustible characteristics of aerated concrete blocks, adjusts the raw material composition and the gasification and pore-forming process, and adds an appropriate amount of sound-insulating and fire-resistant functional materials. This results in blocks with better sound insulation and high-temperature stability, while maintaining necessary strength, dimensional stability, and construction applicability.

[0005] The technical effect described in this invention is achieved through the following technical solution: a soundproof and fireproof aerated concrete block, which, by weight, comprises the following raw materials: 36-44 parts quartz sand powder, 12-17 parts fly ash, 15-19 parts ordinary silicate cement, 9-13 parts quicklime, 2.5-3.8 parts desulfurized gypsum, 4-7 parts barite powder, 2.5-4.5 parts expanded vermiculite powder, 1.2-2.5 parts sepiolite powder, 1-1.8 parts silica fume, 0.25-0.5 parts basalt short chopped fiber, 0.7-1.2 parts sodium silicate aqueous solution, 0.08-0.13 parts aluminum powder paste, and 58-64 parts mixing water.

[0006] Preferably, the quartz sand powder has a fineness of passing through a 200-mesh sieve; Preferably, the barite powder has a fineness of 400-800 mesh; Preferably, the particle size of the expanded vermiculite powder is 100-200 mesh; if the particle size is too large, it is easy to form local weak areas, and if the particle size is too fine, the water absorption is large, which can easily affect the fluidity of the slurry. Preferably, the fineness of the sepiolite powder is 200-400 mesh; Preferably, the basalt short-cut fibers have a length of 3-6 mm and a diameter of 10-20 μm; Preferably, the sodium silicate aqueous solution has a modulus of 2 to 3.3 and a solid content of 35 to 45%. Preferably, the effective aluminum powder content in the aluminum powder paste is 65-75% by mass; Another aspect of the present invention is to provide a method for preparing sound-insulating and fire-resistant aerated concrete blocks, comprising the following steps: S1: The expanded vermiculite powder is pre-wetted with mixing water for 10-20 minutes to obtain pre-wetted expanded vermiculite powder; S2: Take the mixing water, add sodium silicate aqueous solution and sepiolite powder, stir for 3-5 minutes, then slowly add basalt short-cut fibers, continue stirring for 3-6 minutes to obtain fiber dispersion; S3: Add water for mixing the basic slurry into the mixing equipment, control the water temperature to 35-45℃, add quartz sand powder, fly ash, barite powder and silica fume in sequence, stir for 4-6 minutes to fully disperse the barite powder and siliceous fine powder to obtain the first slurry; then add the pre-wetted expanded vermiculite powder obtained in step S1, and continue stirring for 2-3 minutes to obtain the basic slurry; S4: Add ordinary silicate cement and desulfurized gypsum to the basic slurry obtained in step S3 and stir for 2-3 minutes; then add quicklime in 2-3 batches, stirring for 30-60 seconds after each addition, and continue stirring for 2-4 minutes after all the quicklime has been added; then add the fiber dispersion obtained in step S2 and continue stirring for 2-4 minutes to obtain the mixed slurry. S5: Take the mixing water as the water for the aluminum powder paste suspension, and heat this part of the mixing water to 35-45°C; mix the aluminum powder paste with the aluminum powder paste suspension to obtain the aluminum powder paste suspension; add the aluminum powder paste suspension to the mixed slurry obtained in step S4, stir quickly for 30-45 seconds, and immediately pour it into the mold; S6: Place the mold after pouring in step S5 in a static curing chamber for gas generation and pre-curing. After the green body has completed gas generation and expansion and reached a cuttable state, demold it. Cut the demolded green body to obtain the block green body. S7: The block blank is placed in an autoclave for autoclaving. After autoclaving, it is cooled to obtain sound-insulating and fireproof aerated concrete blocks.

[0007] Preferably, the mixing water is added in batches for pre-wetting of expanded vermiculite powder, preparation of fiber dispersion, preparation of aluminum powder paste suspension, and mixing of basic slurry, and the water used in each step is included in the total mixing water; Preferably, in step S1, the amount of mixing water used for pre-wetting is 8-12% of the total amount of mixing water; Preferably, in step S2, the amount of mixing water is 15-18% of the total amount of mixing water; In step S3, the water used for mixing the basic slurry is the remaining amount after deducting the water used for pre-wetting in step S1, the water used for fiber dispersion in step S2, and the water used for aluminum powder paste suspension in step S5 from the total amount of mixing water. Preferably, in step S4, the temperature of the mixed slurry is 38–45°C and the fluidity is 170–200 mm. Preferably, in step S5, the water used in the aluminum powder paste suspension accounts for 0.6% to 1.8% of the total mixing water. Preferably, in step S6, the static temperature is 45-55°C, the relative humidity is not less than 60%, and the static time is 1.5-2.5 hours. Preferably, in step S6, when the billet reaches a cuttable state, the compressive strength of the green billet is 0.25 to 0.35 MPa; Preferably, in step S7, the autoclaving temperature is 180-195℃, the autoclaving pressure is 1-1.3MPa, the constant pressure curing time is 6-8h, the heating and pressurization time is 1.5-2.5h, and the depressurization time is 1.5-2.5h.

[0008] The beneficial effects of this invention are as follows: This invention utilizes the high density and chemical stability of barite powder to construct a relatively uniformly distributed sound-blocking zone within the aerated concrete block. When sound waves pass through the block, they must traverse material regions with varying densities and impedances, weakening the direct sound transmission path and improving sound insulation. This invention controls the amount of barite powder within an appropriate range and, during preparation, disperses it together with quartz sand powder, fly ash, and silica fume. This aims to reduce barite powder settling and localized enrichment, avoiding the weakening of the lightweight and thermal insulation properties of aerated concrete blocks by simply increasing weight to improve sound insulation.

[0009] Furthermore, utilizing the layered porous structure and refractory insulation properties of expanded vermiculite powder, a lightweight refractory zone with sound wave reflection, deflection, and dissipation effects is formed inside the block. During sound wave propagation, the porous layered structure impedes the propagation path, lengthening it and increasing energy attenuation. Under high-temperature conditions, expanded vermiculite powder also helps maintain the thermal insulation stability of the block. Due to the strong water absorption of expanded vermiculite powder, this invention uses partial mixing water for pre-wetting during preparation to reduce local water-cement ratio changes caused by instantaneous water absorption in the main slurry, thus facilitating the stable gas generation process of aluminum powder. Sepiolite powder and sodium silicate aqueous solution mainly play a role in dispersion, suspension, and foam stabilization in the system. Sepiolite powder has a fibrous or chain-like structure, which helps improve the suspension stability of the slurry and slows down the sedimentation of barite powder; sodium silicate aqueous solution can improve the wetting and dispersion state of inorganic particles and basalt short-cut fibers, and also avoids local alkalinity fluctuations caused by insufficient dissolution of solid sodium silicate in a short time. When the two are combined, the distribution of barite powder, expanded vermiculite powder and basalt short-cut fibers in the slurry is more uniform, and problems such as coarsening of pore structure, local enrichment and fiber agglomeration are alleviated.

[0010] Basalt chopped fibers, belonging to inorganic high-temperature resistant fibers, are added to the slurry after pre-dispersion in sepiolite powder and sodium silicate aqueous solution, allowing for relatively uniform distribution within the pore walls and cementitious skeleton. This fiber structure helps limit the propagation of microcracks under drying shrinkage, cutting, and high-temperature conditions, improving the structural integrity of the blocks during handling, construction, and heating. Microcracks easily become weak channels for the propagation of sound waves, heat, and smoke; the suppression of microcracks by basalt chopped fibers helps maintain the sound insulation and fire resistance of the blocks. Silica fume, with its fine particle size and high activity, can fill the micro-voids in the pore walls and cementitious skeleton, and participates in the calcium silicate reaction during autoclaving. The combination of silica fume with quartz sand powder, fly ash, quicklime, cement, and desulfurized gypsum enables the blocks to form a relatively stable hydrated calcium silicate cementitious skeleton after autoclaving, improving pore wall strength and dimensional stability. This structure helps reduce the problems of loose pore walls and decreased strength that may occur after the addition of functional fillers, so that sound insulation and fireproofing modification does not come at the cost of significantly sacrificing the basic mechanical properties of the blocks.

[0011] In the preparation method of this invention, pre-wetting of expanded vermiculite powder reduces water absorption disturbance; pre-dispersion of basalt chopped fibers reduces fiber agglomeration; barite powder is first dispersed together with fine silica powder to reduce sedimentation and local enrichment; quicklime is added in batches to control the rate of heat release during digestion; and aluminum powder paste is added last and briefly stirred to ensure that the main gas generation process occurs within the mold. These steps work together to obtain a more uniform pore structure, reduce coarse pores, interconnected pores, mold collapse, and local cracks, thus maintaining a good balance between lightweight structure, sound insulation, and fire resistance in the building blocks. Attached Figure Description

[0012] Figure 1 The diagram shows the sound insulation test results of the blocks obtained in Example 1 and Comparative Examples 1-5; Figure 1 a represents the airborne sound insulation-frequency curve of the wall specimens obtained in Example 1, Comparative Example 1, and Comparative Example 2; Figure 1 b is the airborne sound insulation-frequency curve of the wall specimens obtained in Example 1, Comparative Example 3, Comparative Example 4 and Comparative Example 5; Figure 2 The graph shows the fire resistance and high-temperature structural stability test results of the blocks obtained in Example 1 and Comparative Examples 1-5. Figure 2 'a' represents the compressive strength retention rate after high temperature. Figure 2 b represents the mass loss rate after high temperature. Figure 2 c represents the linear shrinkage rate after high temperature; Figure 3 The graph shows the dry density test results of the blocks obtained in Example 1 and Comparative Examples 3-5; Figure 3 a represents the dry density test results at different heights. Figure 3 b represents the test results of the upper and lower dry density deviation and the coefficient of variation of dry density. Detailed Implementation

[0013] The technical solution 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 some embodiments of the present invention, and not all embodiments. Unless otherwise specified, the raw materials involved in the present invention are all purchased through conventional commercial channels. Experimental methods without specific conditions are conventional methods and conditions well known in the art, or according to the conditions recommended by the instrument manufacturer.

[0014] Example 1: A soundproof and fireproof aerated concrete block, by weight, comprises the following raw materials: 40 parts quartz sand powder, 15 parts fly ash, 17 parts ordinary silicate cement, 11 parts quicklime, 3 parts desulfurized gypsum, 5.5 parts barite powder, 3.5 parts expanded vermiculite powder, 2 parts sepiolite powder, 1.5 parts silica fume, 0.35 parts basalt short chopped fiber, 1 part sodium silicate aqueous solution, 0.1 parts aluminum powder paste, and 62 parts mixing water.

[0015] The quartz sand powder has a fineness that passes through a 200-mesh sieve; The fineness of the barite powder is 600 mesh; The expanded vermiculite powder has a particle size of 150 mesh; The fineness of the sepiolite powder is 300 mesh; The basalt short-cut fibers are 4 mm in length and 15 μm in diameter; The sodium silicate aqueous solution has a modulus of 2.5 and a solid content of 40%. The effective aluminum powder content in the aluminum powder paste is 70% by mass. The preparation of the sound-insulating and fire-resistant aerated concrete blocks includes the following steps: S1: The expanded vermiculite powder is pre-wetted with 10% of the total mixing water for 15 minutes to obtain pre-wetted expanded vermiculite powder; The mixing water is added in batches and used for pre-wetting of expanded vermiculite powder, preparation of fiber dispersion, preparation of aluminum powder paste suspension and mixing of basic slurry. The water used in each step is included in the total mixing water. S2: Take 16% of the total mixing water, add sodium silicate aqueous solution and sepiolite powder, stir for 4 minutes, then slowly add basalt short-cut fibers, continue stirring for 5 minutes to obtain fiber dispersion. S3: Add water for mixing the basic slurry into the mixing equipment, control the water temperature to 40℃, add quartz sand powder, fly ash, barite powder and silica fume in sequence, stir for 5 minutes to fully disperse the barite powder and silica fine powder to obtain the first slurry; then add the pre-wetted expanded vermiculite powder obtained in step S1, and continue stirring for 2.5 minutes to obtain the basic slurry; The water used for mixing the basic slurry is the remaining amount after deducting the water used for pre-wetting in step S1, the water used for fiber dispersion in step S2, and the water used for aluminum powder paste suspension in step S5 from the total amount of mixing water. S4: Add ordinary silicate cement and desulfurized gypsum to the basic slurry obtained in step S3 and stir for 2.5 min; then add quicklime in two batches, stirring for 60 s after each addition, and continue stirring for 3 min after all the quicklime has been added; then add the fiber dispersion obtained in step S2 and continue stirring for 3 min to obtain a mixed slurry with a temperature of 42℃ and a flowability of 190 mm. S5: Take 1.2% of the total mixing water as the water for the aluminum powder paste suspension, and heat this part of the mixing water to 40°C; mix the aluminum powder paste with the aluminum powder paste suspension to obtain the aluminum powder paste suspension; add the aluminum powder paste suspension to the mixed slurry obtained in step S4, stir quickly for 40 seconds, and immediately pour it into the mold; S6: Place the mold after pouring in step S5 in a static curing chamber for gas generation and pre-curing. The static curing temperature is 50℃, the relative humidity is not less than 60%, and the static curing time is 2 hours. After the green body has completed gas generation and expansion and reached a cuttable state, demold it. Cut the green body with a green compressive strength of 0.3MPa after demolding to obtain a 600mm×200mm×150mm block green body. S7: The block blank is placed in an autoclave for autoclaving. The autoclaving temperature is 185℃, the autoclaving pressure is 1.2MPa, the constant pressure curing time is 7h, the heating and pressurization time is 2h, the depressurization time is 2h, and the block is cooled after autoclaving to obtain soundproof and fireproof aerated concrete blocks.

[0016] Example 2: A soundproof and fireproof aerated concrete block, by weight, comprises the following raw materials: 36 parts quartz sand powder, 12 parts fly ash, 15 parts ordinary silicate cement, 9 parts quicklime, 2.5 parts desulfurized gypsum, 4 parts barite powder, 2.5 parts expanded vermiculite powder, 1.2 parts sepiolite powder, 1 part silica fume, 0.25 parts basalt short chopped fiber, 0.7 parts sodium silicate aqueous solution, 0.08 parts aluminum powder paste, and 58 parts mixing water.

[0017] The quartz sand powder has a fineness that passes through a 200-mesh sieve; The barite powder has a fineness of 400 mesh; The expanded vermiculite powder has a particle size of 100 mesh; The fineness of the sepiolite powder is 200 mesh; The basalt short-cut fibers are 3 mm in length and 20 μm in diameter; The sodium silicate aqueous solution has a modulus of 2 and a solid content of 35%. The effective aluminum powder content in the aluminum powder paste is 65% by mass. The preparation of the sound-insulating and fire-resistant aerated concrete blocks includes the following steps: S1: The expanded vermiculite powder is pre-wetted with 8% of the total mixing water for 10 minutes to obtain pre-wetted expanded vermiculite powder; The mixing water is added in batches and used for pre-wetting of expanded vermiculite powder, preparation of fiber dispersion, preparation of aluminum powder paste suspension and mixing of basic slurry. The water used in each step is included in the total mixing water. S2: Take 15% of the total mixing water, add sodium silicate aqueous solution and sepiolite powder, stir for 3 minutes, then slowly add basalt short-cut fibers, continue stirring for 3 minutes to obtain fiber dispersion. S3: Add water for mixing the basic slurry into the mixing equipment, control the water temperature to 35℃, add quartz sand powder, fly ash, barite powder and silica fume in sequence, stir for 6 minutes to fully disperse the barite powder and silica fine powder to obtain the first slurry; then add the pre-wetted expanded vermiculite powder obtained in step S1, and continue stirring for 3 minutes to obtain the basic slurry; The water used for mixing the basic slurry is the remaining amount after deducting the water used for pre-wetting in step S1, the water used for fiber dispersion in step S2, and the water used for aluminum powder paste suspension in step S5 from the total amount of mixing water. S4: Add ordinary silicate cement and desulfurized gypsum to the basic slurry obtained in step S3 and stir for 2 minutes; then add quicklime in two batches, stirring for 50 seconds after each addition, and continue stirring for 2 minutes after all the quicklime has been added; then add the fiber dispersion obtained in step S2 and continue stirring for 2 minutes to obtain a mixed slurry with a temperature of 38℃ and a flowability of 170 mm. S5: Take 0.6% of the total mixing water as the water for the aluminum powder paste suspension, and heat this part of the mixing water to 35°C; mix the aluminum powder paste with the aluminum powder paste suspension to obtain the aluminum powder paste suspension; add the aluminum powder paste suspension to the mixed slurry obtained in step S4, stir quickly for 45 seconds, and immediately pour it into the mold; S6: Place the mold after pouring in step S5 in a static curing chamber for gas generation and pre-curing. The static curing temperature is 45℃, the relative humidity is not less than 60%, and the static curing time is 1.5h. After the green body has completed gas generation and expansion and reached a cuttable state, demold it. Cut the green body with a compressive strength of 0.25MPa after demolding to obtain a 600mm×200mm×150mm block green body. S7: The block blank is placed in an autoclave for autoclaving. The autoclaving temperature is 180℃, the autoclaving pressure is 1MPa, the constant pressure curing time is 8h, the heating and pressurization time is 1.5h, the depressurization time is 1.5h, and the block is cooled after autoclaving to obtain soundproof and fireproof aerated concrete blocks.

[0018] Example 3: A soundproof and fireproof aerated concrete block, by weight, comprises the following raw materials: 44 parts quartz sand powder, 17 parts fly ash, 19 parts ordinary silicate cement, 13 parts quicklime, 3.8 parts desulfurized gypsum, 7 parts barite powder, 4.5 parts expanded vermiculite powder, 2.5 parts sepiolite powder, 1.8 parts silica fume, 0.5 parts basalt short chopped fiber, 1.2 parts sodium silicate aqueous solution, 0.13 parts aluminum powder paste, and 64 parts mixing water.

[0019] The quartz sand powder has a fineness that passes through a 200-mesh sieve; The fineness of the barite powder is 800 mesh; The expanded vermiculite powder has a particle size of 200 mesh; The fineness of the sepiolite powder is 400 mesh; The basalt short-cut fibers are 6 mm in length and 10 μm in diameter; The sodium silicate aqueous solution has a modulus of 3.3 and a solid content of 45%. The effective aluminum powder content in the aluminum powder paste is 75% by mass. The preparation of the sound-insulating and fire-resistant aerated concrete blocks includes the following steps: S1: The expanded vermiculite powder is pre-wetted with 12% of the total mixing water for 20 minutes to obtain pre-wetted expanded vermiculite powder; The mixing water is added in batches and used for pre-wetting of expanded vermiculite powder, preparation of fiber dispersion, preparation of aluminum powder paste suspension and mixing of basic slurry. The water used in each step is included in the total mixing water. S2: Take 18% of the total mixing water, add sodium silicate aqueous solution and sepiolite powder, stir for 5 minutes, then slowly add basalt short-cut fibers, continue stirring for 6 minutes to obtain fiber dispersion. S3: Add water for mixing the basic slurry into the mixing equipment, control the water temperature to 45℃, add quartz sand powder, fly ash, barite powder and silica fume in sequence, stir for 4 minutes to fully disperse the barite powder and silica fine powder to obtain the first slurry; then add the pre-wetted expanded vermiculite powder obtained in step S1, and continue stirring for 2 minutes to obtain the basic slurry; The water used for mixing the basic slurry is the remaining amount after deducting the water used for pre-wetting in step S1, the water used for fiber dispersion in step S2, and the water used for aluminum powder paste suspension in step S5 from the total amount of mixing water. S4: Add ordinary silicate cement and desulfurized gypsum to the basic slurry obtained in step S3 and stir for 3 minutes; then add quicklime in 3 portions, stirring for 30 seconds after each addition, and continue stirring for 4 minutes after all the quicklime has been added; then add the fiber dispersion obtained in step S2 and continue stirring for 4 minutes to obtain a mixed slurry with a temperature of 45℃ and a flowability of 200 mm. S5: Take 1.8% of the total mixing water as the water for the aluminum powder paste suspension, and heat this part of the mixing water to 45°C; mix the aluminum powder paste with the aluminum powder paste suspension to obtain the aluminum powder paste suspension; add the aluminum powder paste suspension to the mixed slurry obtained in step S4, stir quickly for 30 seconds, and immediately pour it into the mold; S6: Place the mold after pouring in step S5 in a static curing chamber for gas generation and pre-curing. The static curing temperature is 55℃, the relative humidity is not less than 60%, and the static curing time is 2.5h. After the green body has completed gas generation and expansion and reached a cuttable state, demold it. Cut the green body with a compressive strength of 0.35MPa after demolding to obtain a 600mm×200mm×150mm block green body. S7: The block blank is placed in an autoclave for autoclaving. The autoclaving temperature is 195℃, the autoclaving pressure is 1.3MPa, the constant pressure curing time is 6h, the heating and pressurization time is 2.5h, the depressurization time is 2.5h, and the block is cooled after autoclaving to obtain soundproof and fireproof aerated concrete blocks.

[0020] Comparative Example 1: Barite powder was not added, but an equal amount of quartz sand powder was replaced with barite powder. All other raw materials and steps were the same as in Example 1. This was used to verify the contribution of barite powder to sound insulation performance.

[0021] Comparative Example 2: No expanded vermiculite powder was added; instead, an equal amount of expanded vermiculite powder was replaced with fly ash. The mixing water used for pre-wetting the expanded vermiculite powder in the original step S1 was incorporated into the basic slurry mixing water in step S3. The remaining raw materials and steps were consistent with those in Example 1. This was used to verify the effects of expanded vermiculite powder on fire resistance, heat insulation, sound wave dissipation, and lightweight balance.

[0022] Comparative Example 3: In step S1, the expanded vermiculite powder is not pre-wetted. Instead, the expanded vermiculite powder is directly added to the first slurry in step S3. The pre-wetting mixing water used in step S1 is incorporated into the basic slurry mixing water in step S3. The remaining raw materials and steps are consistent with those in Example 1. This is used to verify the role of the expanded vermiculite powder pre-wetting step in maintaining the stability of the local water-cement ratio of the slurry and protecting the integrity of the aerated pore structure.

[0023] Comparative Example 4: The fiber dispersion preparation in step S2 was not performed; sodium silicate aqueous solution, sepiolite powder and basalt short-cut fibers were directly added to the base slurry in step S4; the mixing water used in step S2 was incorporated into the mixing water of the base slurry in step S3, and the remaining raw materials and steps were consistent with those in Example 1; this was used to verify the effect of the pre-dispersion process on the uniform distribution of fibers and the inhibition of the propagation of microcracks in the blocks.

[0024] Comparative Example 5: In step S4, quicklime was added all at once instead of in batches, while the remaining raw materials and steps were consistent with those in Example 1; this was used to verify the effect of adding quicklime in batches on the slurry temperature and gas generation stability.

[0025] Performance Testing: The flowability of the mixed slurry obtained in step S4 of Examples 1-3 and Comparative Examples 1-5, the temperature of the mixed slurry before adding aluminum powder paste, the static expansion rate, the static settling rate, and the compressive strength of the green billet in a cuttable state were measured to evaluate the castability, suspension stability, and gas generation and molding stability of the slurry after the addition of functional fillers. The static expansion rate was calculated as the increase in billet height relative to the casting height after static settling, and the static settling rate was calculated as the ratio of the difference between the maximum expansion height of the billet and the final static settling height. This section focuses on illustrating whether barite powder settling, water absorption of expanded vermiculite powder, fiber agglomeration, and concentrated heat release from quicklime adversely affect the gas generation and molding stability of the billet. The test results are shown in Table 1.

[0026] The dry density, compressive strength, water absorption rate, and drying shrinkage of the aerated concrete blocks obtained in Examples 1-3 and Comparative Examples 1-5 were measured according to GB / T 11969-2020. The thermal conductivity was measured according to GB / T 10294-2008 to evaluate whether the present invention, after introducing sound-insulating and fire-resistant functional components, still maintains the lightweight, thermal insulation, and basic mechanical properties of aerated concrete blocks. This data serves as basic performance support, mainly illustrating that the examples improved sound insulation and fire-resistant performance without significantly sacrificing dry density, compressive strength, and thermal conductivity. The test results are shown in Table 2.

[0027] To evaluate sound insulation performance, wall specimens were constructed using the same thickness, mortar, and construction method, with the blocks obtained in Example 1 and Comparative Examples 1-5 respectively. Airborne sound insulation performance was then tested. The airborne sound insulation of the walls was tested according to GB / T 45305.2-2025, and the single-value sound insulation evaluation quantity was calculated using the building sound insulation evaluation method. Sound insulation results are expressed as an airborne sound insulation quantity-frequency curve. Figure 1 a represents the airborne sound insulation frequency curve of the wall specimens obtained in Example 1, Comparative Example 1, and Comparative Example 2, used to illustrate the influence of barite powder and expanded vermiculite powder on sound insulation performance. Figure 1 b shows the airborne sound insulation-frequency curves of the wall specimens obtained in Examples 1, 3, 4 and 5, which are used to illustrate the effects of pre-wetting of expanded vermiculite powder, pre-dispersion of fibers and batch addition of quicklime on the stability of gas generation and sound insulation effect.

[0028] To evaluate fire resistance and high-temperature structural stability, the blocks obtained in Example 1 and Comparative Examples 1-5 were subjected to non-combustibility evaluation and performance tests after high-temperature treatment. The non-combustibility evaluation was conducted according to GB / T 5464-2010, recording furnace temperature rise, continuous combustion time, sample mass loss rate, and non-combustibility determination results. High-temperature treatment was performed at two temperature levels: 600℃ and 800℃. After holding at these temperatures for 2 hours, the blocks were allowed to cool naturally to room temperature. The compressive strength retention rate, mass loss rate, and linear shrinkage rate after high-temperature treatment were measured to evaluate the structural retention capacity and volume stability of the blocks after high-temperature treatment. Performance results after high-temperature treatment are presented in [data missing]. Figure 2 It means that, among them Figure 2 'a' represents the compressive strength retention rate after high temperature. Figure 2 b represents the mass loss rate after high temperature. Figure 2 c represents the linear shrinkage rate after reaching high temperature.

[0029] To further evaluate the uniformity of slurry settling and gas generation during molding, dry density tests were conducted on blocks obtained in Examples 1 and Comparative Examples 3-5 at different heights. Each block was divided into three regions along its height: upper, middle, and lower. Samples were taken from each region to measure their dry density, and the upper / lower dry density deviation and coefficient of variation were calculated. The upper / lower dry density deviation was used to evaluate the settling of barite powder or slurry stratification, while the coefficient of variation was used to evaluate the overall molding uniformity of the block. The results in this section are presented in... Figure 3 It means that, among them Figure 3 a represents the dry density test results at different heights. Figure 3 b represents the test results of the upper and lower dry density deviation and the coefficient of variation of dry density.

[0030] Table 1. Quantitative test results of the molding process of the mixed slurry in the examples and comparative examples.

[0031] Table 2. Test results of physical and mechanical properties of aerated concrete block foundations in the examples and comparative examples.

[0032] As can be seen from Tables 1 and 2, Examples 1 to 3 maintain a good overall level in terms of molding stability, lightweight, compressive strength, thermal insulation performance and dimensional stability. Within the range of raw material ratios and process parameters defined in this application, the blocks can maintain the molding stability, lightweight, mechanical properties and thermal insulation performance required for aerated concrete, which proves the applicability and technical reliability of the technical solution of this invention within the entire protection scope.

[0033] From Table 1 and Figure 3It is evident that Comparative Examples 3-5 exhibit significantly lower molding stability and height-direction uniformity compared to Example 1. In Comparative Example 3, after eliminating the pre-wetting of expanded vermiculite powder, local water absorption disturbance in the slurry increased, static settling rate rose, green blank strength decreased, and the dry density deviation and coefficient of variation of the finished product significantly increased. This indicates that the pre-wetting treatment with expanded vermiculite powder plays a crucial role in maintaining the moisture distribution and stable gas-generating pore structure of the slurry. In Comparative Example 4, after eliminating the fiber dispersion preparation, although the raw material composition remained unchanged, molding stability and dry density uniformity still deteriorated. This suggests that directly adding sodium silicate aqueous solution, sepiolite powder, and basalt chopped fibers is unlikely to achieve the same distribution effect as the pre-dispersion process, easily affecting slurry uniformity and pore wall structure integrity. In Comparative Example 5, after adding quicklime all at once, the slurry temperature significantly increased before the addition of aluminum powder paste, static expansion and settling fluctuations increased, green blank strength decreased, and the dry density difference in the height direction was also large. This indicates that adding quicklime in batches helps control the rate of heat release during digestion, resulting in better matching between slurry thickening and aluminum powder gas generation processes.

[0034] From Table 2 and Figure 1 It is evident that Example 1 achieved a good balance between basic performance and sound insulation performance. In Comparative Example 1, after removing barite powder, the dry density decreased, while the compressive strength and thermal conductivity remained relatively unchanged. However, the airborne sound insulation decreased significantly, indicating that barite powder directly contributes to the improvement of the block's sound insulation performance. In Comparative Example 2, after removing expanded vermiculite powder, the thermal conductivity increased, and the sound insulation performance also decreased, indicating that expanded vermiculite powder not only helps maintain lightweight thermal insulation performance but also plays an auxiliary role in the dissipation of sound waves during propagation. Although Comparative Examples 3, 4, and 5 did not remove the main sound insulation filler, the sound insulation curves were all lower than those of Example 1 due to the disruption of the pre-wetting, pre-dispersion, or controlled feeding processes. This indicates that the sound insulation effect of the block does not only depend on the presence of barite powder and expanded vermiculite powder but is also closely related to the uniformity of the pore structure, the fiber dispersion state, and the stability of the green body forming.

[0035] Depend on Figure 2It is evident that Example 1 outperforms all comparative examples in terms of compressive strength retention, mass loss rate, and linear shrinkage rate after high-temperature treatment, indicating that a complete formulation and controlled process are beneficial for improving the structural retention capacity of the blocks after high-temperature treatment. Comparative Example 1, after omitting barite powder, showed relatively small differences in performance compared to Example 1 after high-temperature treatment, suggesting that barite powder mainly contributes to sound insulation and its impact on fire resistance stability is not the dominant factor. Comparative Example 2, after omitting expanded vermiculite powder, showed a decrease in strength retention and an increase in mass loss rate and linear shrinkage rate after high-temperature treatment, indicating that expanded vermiculite powder is an important component for maintaining high-temperature insulation and volume stability. Comparative Example 4, due to the lack of pre-dispersion of fibers, showed a significant decrease in strength retention after high-temperature treatment, indicating that the fiber dispersion state affects microcrack constraint and structural integrity during heating. Comparative Example 5 showed the most significant performance degradation after high-temperature treatment. Combined with the slurry temperature and static settling results in Table 1, it can be seen that the unstable gas generation caused by the one-time addition of quicklime further weakens the structural retention capacity after high-temperature treatment.

[0036] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A sound-insulating and fire-resistant aerated concrete block, characterized in that, By weight, its composition includes the following raw materials: 36-44 parts quartz sand powder, 12-17 parts fly ash, 15-19 parts ordinary silicate cement, 9-13 parts quicklime, 2.5-3.8 parts desulfurized gypsum, 4-7 parts barite powder, 2.5-4.5 parts expanded vermiculite powder, 1.2-2.5 parts sepiolite powder, 1-1.8 parts silica fume, 0.25-0.5 parts basalt short chopped fiber, 0.7-1.2 parts sodium silicate aqueous solution, 0.08-0.13 parts aluminum powder paste, and 58-64 parts mixing water.

2. The sound-insulating and fire-resistant aerated concrete block according to claim 1, characterized in that, The quartz sand powder has a fineness of passing through a 200-mesh sieve; the barite powder has a fineness of 400-800 mesh; the expanded vermiculite powder has a particle size of 100-200 mesh; and the sepiolite powder has a fineness of 200-400 mesh.

3. The sound-insulating and fire-resistant aerated concrete block according to claim 1, characterized in that, The basalt short-cut fibers have a length of 3–6 mm and a diameter of 10–20 μm.

4. The sound-insulating and fire-resistant aerated concrete block according to claim 1, characterized in that, The sodium silicate aqueous solution has a modulus of 2 to 3.3 and a solid content of 35 to 45%.

5. The sound-insulating and fire-resistant aerated concrete block according to claim 1, characterized in that, The effective aluminum powder content in the aluminum powder paste is 65-75% by mass.

6. A method for preparing sound-insulating and fire-resistant aerated concrete blocks according to any one of claims 1-5, characterized in that, Includes the following steps: S1: The expanded vermiculite powder is pre-wetted with mixing water to obtain pre-wetted expanded vermiculite powder; S2: Take the mixing water, add sodium silicate aqueous solution and sepiolite powder, stir and then slowly add basalt short-cut fibers, continue stirring to obtain fiber dispersion; S3: Add water for mixing the basic slurry into the mixing equipment, control the water temperature, and add quartz sand powder, fly ash, barite powder and silica fume in sequence. Stir to fully disperse the barite powder and siliceous fine powder to obtain the first slurry; then add the pre-wetted expanded vermiculite powder obtained in step S1, and continue stirring to obtain the basic slurry; S4: Add ordinary silicate cement and desulfurized gypsum to the basic slurry obtained in step S3 and stir; then add quicklime in batches, stirring evenly after each addition, and continue stirring after all the quicklime has been added; then add the fiber dispersion obtained in step S2 and continue stirring to obtain a mixed slurry; S5: Take the mixing water as the water for the aluminum powder paste suspension and heat this part of the mixing water; mix the aluminum powder paste with the aluminum powder paste suspension to obtain the aluminum powder paste suspension; add the aluminum powder paste suspension to the mixed slurry obtained in step S4, stir quickly and immediately pour it into the mold; S6: Place the mold after pouring in step S5 in a static curing chamber for gas generation and pre-curing. After the green body has completed gas generation and expansion and reached a cuttable state, demold it. Cut the demolded green body to obtain the block green body. S7: The block blank is placed in an autoclave for autoclaving. After autoclaving, it is cooled to obtain sound-insulating and fireproof aerated concrete blocks.

7. A method for preparing sound-insulating and fire-resistant aerated concrete blocks according to claim 6, characterized in that, In step S1, the amount of mixing water used for pre-wetting is 8-12% of the total mixing water; in step S2, the amount of mixing water used is 15-18% of the total mixing water; in step S3, the amount of water used for mixing the base slurry is the remainder after deducting the water used for pre-wetting in step S1, the water used for fiber dispersion in step S2, and the water used for aluminum powder paste suspension in step S5 from the total mixing water; in step S5, the water used for aluminum powder paste suspension accounts for 0.6-1.8% of the total mixing water.

8. A method for preparing sound-insulating and fire-resistant aerated concrete blocks according to claim 6, characterized in that, In step S4, the temperature of the mixed slurry is 38-45°C and the fluidity is 170-200 mm.

9. A method for preparing sound-insulating and fire-resistant aerated concrete blocks according to claim 6, characterized in that, In step S6, the static stopping temperature is 45-55℃, the relative humidity is not less than 60%, and the static stopping time is 1.5-2.5h; when the billet reaches the cuttable state, the compressive strength of the green billet is 0.25-0.35MPa.

10. A method for preparing sound-insulating and fire-resistant aerated concrete blocks according to claim 6, characterized in that, In step S7, the autoclaving temperature is 180-195℃, the autoclaving pressure is 1-1.3MPa, the constant pressure curing time is 6-8h, the heating and pressurization time is 1.5-2.5h, and the depressurization time is 1.5-2.5h.

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