Calcium-sodium synergistically excited silicon-aluminum solid waste-based autoclaved aerated concrete block and application thereof

Abstract

The invention discloses a calcium-sodium synergistically excited silicon-aluminum solid waste-based autoclaved aerated concrete block and application, and relates to the technical field of solid waste resource utilization and building materials. According to the calcium-sodium synergistically excited silicon-aluminum solid waste-based autoclaved aerated concrete block, fly ash and blast furnace slag are used as silicon-aluminum raw materials, a Ca < 2 + > and Na < + > synergistically excited system is adopted, and NaOH and CaO are used as alkali activators in the excitation system; the calcium-sodium synergistically excited silicon-aluminum solid waste-based autoclaved aerated concrete block is prepared from the following components in percentage by weight: 25 to 35 parts of fly ash, 60 to 80 parts of blast furnace slag, 5 to 10 parts of lime, 1 to 5 parts of gypsum, 1 to 5 parts of NaOH, 0.1 to 0.3 part of aluminum powder and 0 to 5 parts of foam stabilizer. The autoclaved aerated concrete block with good performance is prepared, and the requirement of the autoclaved aerated concrete block can be met. According to the method, efficient activation and utilization of the silicon-aluminum solid waste are achieved, and the purpose of recycling the silicon-aluminum industrial solid waste is achieved.

Description

Technical Field

[0001] This invention relates to the fields of solid waste resource utilization and building materials technology, and in particular to a calcium-sodium synergistic activated silica-alumina solid waste-based autoclaved aerated concrete block and its application. Background Technology

[0002] Autoclaved aerated concrete (AAC) blocks are generally porous concrete products made from fly ash, lime, cement, gypsum, and slag as the main raw materials, with the addition of foaming agents, regulators, and bubble stabilizers, through processes such as batching and mixing, pouring, static curing, cutting, and high-pressure autoclaving.

[0003] Autoclaved aerated concrete (AAC), as a low-energy and environmentally friendly new building material, possesses significant advantages: it is not only lightweight but also boasts excellent thermal insulation, high strength, earthquake resistance, ease of processing, high-temperature resistance, and sound insulation properties. A single material can meet the insulation requirements of walls. Its production uses siliceous raw materials (such as sand, fly ash, and silica-containing tailings) and calcareous raw materials (such as lime and cement) as core components, supplemented with aluminum powder as a foaming agent. Through multiple processes including batching, mixing, pouring, pre-curing, cutting, autoclaving, and maintenance, a lightweight porous silicate product is ultimately formed. The raw materials for this material are widely available. Especially when fly ash is used as a raw material, it can achieve comprehensive utilization of industrial waste, reduce environmental pollution, avoid farmland destruction, and balance social and economic benefits. Therefore, it has become a preferred wall material to replace traditional solid clay bricks, with broad market application prospects.

[0004] Silicon-aluminate industrial solid waste typically refers to industrial solid waste containing silicon and aluminum, primarily originating from industrial processes such as coal-fired power generation and coal mining. Examples of silicon-aluminate solid waste include coal gangue and fly ash. Currently, utilizing silicon-aluminate solid waste to produce building materials is a key research direction in the field of sustainable development.

[0005] In existing technologies, the application of solid waste largely relies on its aggregate function and pozzolanic effect, used for brick making, block production, or blending into cement and concrete. However, fly ash itself has low reactivity, resulting in insufficient early reaction under conventional curing conditions, slow strength gain, limited water demand and dosage, and difficulty in forming a continuous, dense gel skeleton and stable pore structure. This leads to problems such as insufficient strength, difficulty in demolding, uneven pore structure, and increased shrinkage in the finished product, hindering its efficient utilization. This characteristic severely restricts its efficient utilization in the building materials field. Therefore, developing a technical solution that can fully utilize the application value of siliceous aluminate industrial solid waste has become a key issue that urgently needs to be addressed by those skilled in the art. Summary of the Invention

[0006] To address the technical problems existing in the prior art, embodiments of the present invention provide a calcium-sodium synergistically activated silica-alumina solid waste-based autoclaved aerated concrete block and its application. The technical solution is as follows:

[0007] A calcium-sodium synergistic activated silica-alumina solid waste-based autoclaved aerated concrete block, wherein the calcium-sodium synergistic activated silica-alumina solid waste-based autoclaved aerated concrete block uses fly ash and blast furnace slag as silica-alumina raw materials, and adopts Ca 2+ Na + A synergistic activation system, wherein NaOH and CaO are used as alkaline activators;

[0008] The calcium-sodium synergistic activated silica-alumina solid waste-based autoclaved aerated concrete blocks, by weight, comprise the following components:

[0009] Fly ash: 25-35 parts, blast furnace slag: 60-80 parts, lime: 5-10 parts, gypsum: 1-5 parts, NaOH: 1-5 parts, aluminum powder: 0.1-0.3 parts, foam stabilizer: 0-5 parts.

[0010] Optionally, the calcium-sodium synergistically activated silica-alumina solid waste-based autoclaved aerated concrete block comprises, by weight, the following components:

[0011] Fly ash: 30 parts, blast furnace slag: 70 parts, lime: 8 parts, gypsum: 2 parts, NaOH: 3.5 parts, aluminum powder: 0.150-0.275 parts, foam stabilizer: 0-2.5 parts.

[0012] Optionally, the gypsum is desulfurized gypsum;

[0013] And / or, the NaOH is industrial caustic soda flakes;

[0014] And / or, the amount of aluminum powder added is 0.175~0.225 parts;

[0015] And / or, the foam stabilizer is sodium dodecylbenzenesulfonate, and the amount added is 0~2.5 parts.

[0016] The method for preparing calcium-sodium synergistically activated silica-alumina solid waste-based autoclaved aerated concrete blocks includes the following steps:

[0017] 1) Dry the fly ash, blast furnace slag, lime, and gypsum;

[0018] 2) The dried fly ash, blast furnace slag, lime, gypsum, and NaOH from step 1) are mixed in a specific ratio and then pulverized to obtain composite mineral powder, wherein the specific surface area of ​​the composite mineral powder is ≥510 m². 2 / kg, D50 controlled at 12-15μm;

[0019] 3) Mix the composite mineral powder obtained in step 2) with the foam stabilizer for the first time, then add water for the second time, and then add aluminum powder foaming agent for the third time.

[0020] 4) The slurry obtained in step 3) is injected into the mold, and after static gas generation and curing, the calcium-sodium synergistic activated silica-alumina solid waste-based autoclaved aerated concrete block is obtained.

[0021] Optionally, in step 1), the drying temperature is 105±5℃, and the drying time is adjusted according to the initial moisture content of the material to ensure that the final moisture content is ≤2%.

[0022] Optionally, in step 2), the pulverization is performed by adding the material to a ball mill for ball milling.

[0023] And / or, the D50 of the composite mineral powder is controlled at 13-14 μm;

[0024] And / or, the process parameters for the ball milling process are: ball-to-material ratio of 1:1 to 3:1 or 2:1, rotation speed of 30-50 r / min or 40 r / min, and ball milling time of 20 ± 5 min.

[0025] Optionally, in step 3), the first stirring rate is 140±5 r / min, and the stirring time is 1-3 min or 2 min;

[0026] And / or, the second stirring rate is 285±10 r / min, and the stirring time is 1-5 min or 3 min;

[0027] And / or, the second stirring is done with warm water at 40-50℃ or 45℃;

[0028] And / or, the water-cement ratio of the second mixing is controlled at 0.4-0.5 or 0.44;

[0029] And / or, the third stirring rate is 285±10 r / min, and the stirring time is 10±10 s.

[0030] Optionally, in step 4), the settling temperature is 50-60°C and the gas generation time is 120-140 min;

[0031] And / or, the curing is autoclaving, with curing conditions of 1-1.5 MPa, 150-200℃ or 1.15 MPa, 180℃, and curing time of 8-10 hours.

[0032] The application of the calcium-sodium synergistic activation of silica-alumina solid waste-based autoclaved aerated concrete blocks in the preparation of prefabricated walls.

[0033] A prefabricated wall structure comprising: the aforementioned calcium-sodium synergistically activated silica-alumina solid waste-based autoclaved aerated concrete block.

[0034] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0035] This invention discloses a calcium-sodium synergistically activated silica-alumina solid waste-based autoclaved aerated concrete block and its preparation method, comprehensively utilizing silica-alumina raw materials and Ca... 2+ Na + A synergistic activation mechanism was employed to produce high-performance autoclaved aerated concrete (AAC) blocks that meet the performance testing requirements of AAC blocks (GB / T 11969-2020), achieving resource utilization of siliceous aluminous industrial solid waste. The calcium-sodium synergistic activation mechanism of this invention, applied to siliceous aluminous solid waste-based AAC blocks, after steam curing for 8-10 hours, yields compressive strengths of 4.5 MPa to 6.5 MPa and densities of 510 to 630 kg / m³. 3 .

[0036] This invention utilizes calcium and sodium synergistic activation to produce autoclaved aerated concrete (AAC) blocks based on aluminosilicate solid waste, enabling efficient utilization of aluminosilicate industrial solid waste and providing a new avenue for raw materials needed by the building materials industry. This invention achieves highly efficient activation and utilization of aluminosilicate solid waste. The AAC blocks produced can contain up to 60-80 parts by weight of blast furnace slag, for example, 70 parts, and 25-35 parts by weight of fly ash. Furthermore, the alkali-activated cementitious material completely replaces cement during the preparation of the AAC blocks, eliminating the need for cement addition. This invention achieves high solid waste content and increased strength without introducing cement: the compressive strength can reach up to 5.7-6.5 MPa, while existing technologies, such as comparative examples, only achieve 2.8-3.0 MPa at similar densities. The resulting blocks exhibit excellent performance, meeting the requirements for AAC concrete use and achieving the goal of resource utilization of aluminosilicate industrial solid waste.

[0037] This invention fully utilizes the Ca in NaOH and lime 2+ Na + This invention synergistically stimulates the production of silica-alumina industrial solid waste. Compared to existing technologies, the Ca... 2+ Na + The synergistic stimulation system has the following innovative advantages:

[0038] (1) Synergistic effect mechanism of dual alkalis: A dynamic alkaline environment is constructed through the combined action of NaOH (e.g., industrial caustic soda flakes) and lime (CaO). Among them, the rapid dissociation of NaOH provides OH- - It accelerates the breaking of Si-O and Al-O bonds in the glassy structure of fly ash; at the same time, lime hydration generates Ca(OH)2, continuously releasing Ca. 2+And maintain the liquid phase pH > 12.5. The two work synergistically to promote the deep depolymerization of active aluminosilicates, and the growth of C-(A)-SH gel and NASH gel forms a dense three-dimensional network structure. Experimental results by XPS binding energy analysis show that Ca in the dual-alkali system... 2+ With [SiO4] 4- The degree of association was increased by 37%, and the density of the gel structure was significantly improved.

[0039] (2) Calcium-sulfur synergistic regulation: Gypsum (CaSO4·2H2O) is introduced as a functional regulating phase, and the SO4 released by it... 2- With Ca 2 + Al 3+ The reaction produces ettringite (AFt), which fills microcracks and delays the reaction of OH. - The reduced consumption rate extends the setting time to 120-140 minutes, effectively improving workability.

[0040] (3) Co-activation of solid waste: The complementary properties of fly ash and blast furnace slag are enhanced in a dual-alkali environment. The heat of lime hydration promotes the reaction of fly ash, while MgO in slag generates magnesia phase, which interweaves with CASH to form a composite structure, resulting in a compressive strength of up to 6.5 MPa and a drying shrinkage rate of 0.26 mm / m. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 The XRD diffraction pattern of fly ash indicates that its main crystalline phases are quartz and mullite, with a high amount of glassy phase material, making it a high-quality raw material for preparing alkali-activated cementitious materials.

[0043] Figure 2 The XRD diffraction pattern of blast furnace slag indicates that its main crystalline phases are quartz, calcite and mullite, with a high amount of glassy phase material, making it a high-quality raw material for preparing alkali-activated cementitious materials.

[0044] Figure 3 The XRD diffraction pattern of lime indicates that its main phases are calcium hydroxide and calcium oxide, with a higher proportion of crystalline phases and a lower proportion of glassy phases. This suggests that lime, after hydration, not only provides a favorable alkaline environment but also provides sufficient Ca to initiate the hydration reaction. 2+ ;

[0045] Figure 4 The XRD diffraction pattern of desulfurized gypsum shows that its main phases are calcium sulfate dihydrate, calcium oxide, and quartz, indicating that desulfurized gypsum can release Ca2+ in an alkaline-activated environment. 2+ It provides a calcium source for the hydration reaction, and the desulfurized gypsum reacts with Al in the alkaline solution. 3+ and Si 4+ The reaction produces ettringite, which can act as a retarder, thus solving the problem of excessively fast setting rate of alkali-activated cementitious materials.

[0046] Figure 5 This is a process flow diagram provided in Embodiment 1 of the present invention;

[0047] Figure 6 These are the mechanical properties and dry density diagrams provided in Embodiments 1-6 of the present invention;

[0048] Figure 7 These are the thermal conductivity diagrams provided in Embodiments 1-6 of the present invention;

[0049] Figure 8 This is a SEM-EDS image of the hydration product provided in Example 3 of the present invention. The image shows a three-dimensional network structure showing the intertwined growth of C-(A)-SH gel and ettringite.

[0050] Figure 9 These are the heat release rate curves provided in Embodiments 1-6 of the present invention;

[0051] Figure 10 These are fitting diagrams of the kinetic model of the hydration reaction process provided in Examples 1-6 of this invention, wherein... Figure 10 In Figure (a), the kinetic model fitting diagram of the hydration reaction process provided in Examples 1-2 is shown. Figure 10 (b) is a kinetic model fitting diagram of the hydration reaction process provided in Example 3. Figure 10 (c) is a kinetic model fitting diagram of the hydration reaction process provided in Examples 4-6. Detailed Implementation

[0052] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0053] In this invention, blast furnace slag is an industrial solid waste, referring to the slag discharged during the blast furnace ironmaking process, also known as blast furnace slag. During the blast furnace ironmaking process, it is generally a solid waste formed from gangue in the ore, ash in the fuel, and non-volatile components in the solvent (usually limestone).

[0054] In this invention, desulfurization gypsum, also known as flue gas desulfurization gypsum, sulfur gypsum, or FGD gypsum, has the same main component as natural gypsum: calcium sulfate dihydrate (CaSO4·2H2O), with a content ≥93%. Desulfurization gypsum is a byproduct of the FGD process, a technology that uses lime-limestone to recover sulfur dioxide from flue gas from coal or oil combustion. This technology involves grinding lime-limestone into a slurry, which is then used to remove SO2 from the dust-treated flue gas containing SO2 through a slurry scrubber. The lime slurry reacts with SO2 to produce calcium sulfate and calcium sulfite. Calcium sulfite is oxidized to calcium sulfate, yielding the industrial byproduct gypsum, known as desulfurization gypsum, which is widely used in building materials and other industries.

[0055] In this invention, industrial caustic soda flakes refer to industrial sodium hydroxide.

[0056] The purpose of this invention is to provide a calcium-sodium synergistic-activated aluminosilicate solid waste-based autoclaved aerated concrete block and its preparation method. By synergistically activating and organically combining aluminosilicate industrial solid waste, resource utilization is achieved. This invention enables effective treatment of aluminosilicate industrial solid waste and the preparation of autoclaved aerated concrete blocks for use as prefabricated building materials, thereby achieving the goal of comprehensive resource utilization of solid waste.

[0057] To achieve the above objectives, this invention discloses a calcium-sodium synergistically activated silica-alumina solid waste-based autoclaved aerated concrete block and its preparation method. Specifically, this invention designs a calcium-sodium synergistically activated silica-alumina solid waste-based autoclaved aerated concrete block and its preparation method. 2+ Na + A co-activated aluminosilicate solid waste-based autoclaved aerated concrete (AAC) block is disclosed, along with its preparation method and application in prefabricated walls. The AAC block uses fly ash and blast furnace slag as aluminosilicate raw materials, supplemented with lime, gypsum, and NaOH to form an activation system, aluminum powder as a foaming agent, and mixing water. The preparation method includes the following steps: first, the aluminosilicate raw materials, lime, gypsum, and NaOH are dried and ball-milled into powder; then, they are mixed with a foam stabilizer and stirred for the first time; then, water is added and stirred for the second time; then, the foaming agent is added and stirred for the third time; finally, the slurry is poured into a mold, allowed to stand for gas generation, and then autoclaved to obtain the finished product.

[0058] In a preferred embodiment, the present invention provides the following solution: a calcium-sodium synergistically activated silica-alumina solid waste-based autoclaved aerated concrete block, comprising the following raw materials in parts by weight: fly ash: 30 parts, blast furnace slag: 70 parts, lime: 8 parts, desulfurized gypsum: 2 parts, industrial caustic soda flakes: 3.5 parts, and aluminum powder: 0.150~0.275 parts.

[0059] In a preferred embodiment, the preparation method of the present invention includes:

[0060] 1) Proportion fly ash, blast furnace slag, desulfurized gypsum, and lime according to their chemical composition, weigh them, mechanically mix them, and then put them into an oven to dry at a temperature of 105±5℃, ensuring that the final moisture content is ≤2%;

[0061] 2) The dried fly ash, blast furnace slag, lime, and desulfurized gypsum are fed into a ball mill in sequence according to their particle size requirements and ball milled to obtain composite mineral powder;

[0062] 3) Add the appropriate proportion of industrial caustic soda flakes to the obtained composite mineral powder, and continue to ball mill it in a ball mill to mix it evenly;

[0063] 4) Mix the obtained composite mineral powder with the foam stabilizer evenly and stir once. Then add 45℃ warm water, using deionized water as the mixing water, with a water-cement ratio of 0.44, and stir a second time. Then add aluminum powder and stir a third time.

[0064] 5) The obtained slurry is injected into the mold, and after static gas generation and curing, the autoclaved aerated concrete block is obtained.

[0065] Preferably, the ball milling process parameters in step 2) are: ball-to-material ratio 2:1, rotation speed 40 r / min, ball milling time 20 ± 5 min, and the resulting composite mineral powder has a specific surface area ≥ 510 m². 2 / kg, D50 controlled at 12-15μm.

[0066] This invention utilizes Ca 2+ Na + The synergistic activation mechanism can significantly increase the pH value of the slurry, which is beneficial to the decomposition of Si-O and Al-O bonds in the silica-alumina raw materials, and significantly improves the hydration reaction activity, thereby generating more CSH and CAH; the alkaline activator provides the necessary Ca for the main hydration product CSH gel. 2+ .

[0067] Furthermore, the aluminosilicate solid waste in this invention already contains a large amount of aluminosilicate glass, possessing potential hydration activity without calcination. Under a strongly alkaline environment, a large amount of active aluminosilicate dissolves, reacting with an alkaline activator and calcium raw materials to form hydrated calcium silicate gel, providing strength to the material.

[0068] In this invention, the aluminosilicate raw material is ground in a ball mill, which disrupts its glassy structure, causing the coarse, bonded glassy structures to disintegrate and releasing the active glass microspheres within. The grinding process also converts some mechanical energy into the surface or internal energy of the aluminosilicate raw material particles, reducing the bonding energy of the mineral crystals, increasing the contact area between the particles and the alkaline activator, and accelerating the hydration reaction process of the aluminosilicate raw material. However, excessively long grinding times can lead to a decrease in the specific surface area of ​​the aluminosilicate raw material particles because the mechanical heat during grinding causes the fine particles to agglomerate, increasing the specific surface area. The greatest increase in the activity of the aluminosilicate raw material is observed after grinding for 20 ± 5 minutes.

[0069] The first stirring rate is 140±5 r / min, and the stirring time is 1-3 min, preferably 2 min;

[0070] The secondary stirring rate is 285±10 r / min, and the stirring time is 1-5 min, preferably 3 min;

[0071] The third stirring rate is 285±10 r / min, and the stirring time is 10±10 s, preferably 10 s.

[0072] This invention first involves slow stirring for 2 minutes to ensure the powder is fully mixed; then water is added and stirred quickly for 3 minutes to ensure the powder and water are in full contact, thus preparing a uniform slurry with suitable consistency; finally, aluminum powder is added and stirred quickly for 10 seconds. This ensures that the aluminum powder is evenly distributed in the slurry, shortens the stirring time, prevents bubbles from overflowing or breaking due to stirring, and allows the slurry to be injected into the mold before it expands significantly.

[0073] The static gas generation temperature is 50-60℃, and the time is 120-140 min;

[0074] The curing process involves steam curing at 1.15 MPa and 180°C for 8-10 hours.

[0075] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0076] Unless otherwise specified, the experimental methods described in the following embodiments are conventional methods, performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions.

[0077] Unless otherwise specified, all materials and reagents described in the following examples are commercially available.

[0078] In the following embodiments, the experimental methods such as XRD diffraction detection, dry density, compressive strength, and scanning electron microscope-X-ray energy dispersive spectroscopy (SEM-EDS) detection methods are all conventional experimental methods well known to those skilled in the art. Where no specific conditions are specified in the experimental methods, they are usually operated according to conventional conditions.

[0079] In the following embodiments, fly ash can be purchased from Datang Tuoketuo Power Plant, blast furnace slag can be purchased from the solid waste treatment center of Jinshan Power Plant in Hohhot, Inner Mongolia, and lime and desulfurization gypsum can be purchased from Datang Tuoketuo Power Plant.

[0080] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0081] The main chemical compositions of the fly ash, slag, lime, and desulfurization gypsum used in the following examples are shown in Table 1:

[0082] Table 1: Chemical Composition of Each Raw Material (%)

[0083]

[0084] The following examples investigate the effect of the foaming agent on the compressive strength, dry density, and thermal conductivity of autoclaved aerated concrete (AAC) blocks by adjusting the content of aluminum powder in the foaming agent. However, the present invention is not limited thereto. Those skilled in the art will understand that the silica-alumina solid waste-based AAC blocks prepared by the present invention, as long as they include the following components by weight: fly ash: 25-35 parts, blast furnace slag: 60-80 parts, lime: 5-10 parts, gypsum: 1-5 parts, NaOH: 1-5 parts, aluminum powder: 0.1-0.3 parts, and foam stabilizer: 0-5 parts, can all meet the performance test requirements of AAC blocks (GB / T 11969-2020) and achieve the same or similar technical effects as the following examples. Therefore, they will not be described in detail here.

[0085] Example 1

[0086] A calcium-sodium synergistically activated silica-alumina solid waste-based autoclaved aerated concrete block comprises the following raw materials in parts by weight:

[0087] Fly ash: 30 parts, blast furnace slag: 70 parts, lime: 8 parts, desulfurized gypsum: 2 parts, industrial caustic soda flakes: 3.5 parts, aluminum powder: 0.150 parts, foam stabilizer: sodium dodecylbenzene sulfonate, 2.5 parts.

[0088] A method for preparing autoclaved aerated concrete blocks, such as... Figure 1 As shown, it includes the following steps:

[0089] After mixing the above-mentioned aluminosilicate raw materials with sodium hydroxide, lime, desulfurized gypsum, and foam stabilizer evenly, pour the mixture into a mixing pot. First, stir at a stirring rate of 140±5 r / min for 2 minutes. Then, add deionized water at a water-cement ratio of 0.44 and stir at a stirring rate of 285±10 r / min for 3 minutes. Next, add aluminum powder and continue stirring at a stirring rate of 285±10 r / min for 10 seconds. Pour the well-mixed slurry into a mold and let it stand at 50-60℃ for 120-140 minutes to generate gas. Then, cut off the excess part of the upper part of the green body. Finally, after steam curing at 180℃ for 8-10 hours, demold to obtain autoclaved aerated concrete blocks.

[0090] The dry density of the obtained autoclaved aerated concrete blocks was 590 kg / m³. 3 The compressive strength is 5.7 MPa, which meets the performance test requirements of autoclaved aerated concrete blocks (GB / T 11969-2020).

[0091] Example 2

[0092] A calcium-sodium synergistically activated silica-alumina solid waste-based autoclaved aerated concrete block comprises the following raw materials in parts by weight:

[0093] Fly ash: 30 parts, blast furnace slag: 70 parts, lime: 8 parts, desulfurized gypsum: 2 parts, industrial caustic soda flakes: 3.5 parts, aluminum powder: 0.175 parts, foam stabilizer: sodium dodecylbenzene sulfonate, 2.5 parts.

[0094] The preparation method of the autoclaved aerated concrete (AAC) blocks is the same as in Example 1. The resulting AAC blocks have a dry density of 510 kg / m³. 3 The compressive strength is 5.9 MPa, which meets the performance test requirements of autoclaved aerated concrete blocks (GB / T 11969-2020).

[0095] Example 3

[0096] A calcium-sodium synergistically activated silica-alumina solid waste-based autoclaved aerated concrete block comprises the following raw materials in parts by weight:

[0097] Fly ash: 30 parts, blast furnace slag: 70 parts, lime: 8 parts, desulfurized gypsum: 2 parts, industrial caustic soda flakes: 3.5 parts, aluminum powder: 0.200 parts, foam stabilizer: sodium dodecylbenzene sulfonate, 2.5 parts.

[0098] The preparation method of the autoclaved aerated concrete (AAC) blocks is the same as in Example 1. The resulting AAC blocks have a dry density of 630 kg / m³.3 The compressive strength is 6.5 MPa, which meets the performance test requirements of autoclaved aerated concrete blocks (GB / T 11969-2020).

[0099] In the steam curing step of the preparation method, the hydration products of the product of Example 3 were detected by scanning electron microscopy-X-ray energy dispersive spectroscopy (SEM-EDS).

[0100] Figure 8 The image shows the SEM-EDS diagram of the hydration product provided in Example 3. The diagram illustrates the three-dimensional network structure showing the interwoven growth of C-(A)-SH gel and ettringite. The interwoven growth effect is evident. Higher density of interwoven growth indicates a stronger hydration reaction mechanism, which translates to higher strength at the macroscopic level. The SEM-EDS diagrams of the hydration products in other examples are similar to those in Example 3 and will not be described in detail here.

[0101] Example 4

[0102] A calcium-sodium synergistically activated silica-alumina solid waste-based autoclaved aerated concrete block comprises the following raw materials in parts by weight:

[0103] Fly ash: 30 parts, blast furnace slag: 70 parts, lime: 8 parts, desulfurized gypsum: 2 parts, industrial caustic soda flakes: 3.5 parts, aluminum powder: 0.225 parts, foam stabilizer: sodium dodecylbenzene sulfonate, 2.5 parts.

[0104] The preparation method of the autoclaved aerated concrete (AAC) blocks is the same as in Example 1. The resulting AAC blocks have a dry density of 543 kg / m³. 3 The compressive strength is 4.5 MPa, which meets the performance test requirements of autoclaved aerated concrete blocks (GB / T 11969-2020).

[0105] Example 5

[0106] A calcium-sodium synergistically activated silica-alumina solid waste-based autoclaved aerated concrete block comprises the following raw materials in parts by weight:

[0107] Fly ash: 30 parts, blast furnace slag: 70 parts, lime: 8 parts, desulfurized gypsum: 2 parts, industrial caustic soda flakes: 3.5 parts, aluminum powder: 0.250 parts, foam stabilizer: sodium dodecylbenzene sulfonate, 2.5 parts.

[0108] The preparation method of the autoclaved aerated concrete (AAC) blocks is the same as in Example 1. The resulting AAC blocks have a dry density of 480 kg / m³. 3 The compressive strength is 3.7 MPa, which meets the performance test requirements of autoclaved aerated concrete blocks (GB / T 11969-2020).

[0109] Example 6

[0110] A calcium-sodium synergistically activated silica-alumina solid waste-based autoclaved aerated concrete block comprises the following raw materials in parts by weight:

[0111] Fly ash: 30 parts, blast furnace slag: 70 parts, lime: 8 parts, desulfurized gypsum: 2 parts, industrial caustic soda flakes: 3.5 parts, aluminum powder: 0.275 parts, foam stabilizer: sodium dodecylbenzene sulfonate, 2.5 parts.

[0112] The preparation method of the autoclaved aerated concrete blocks is the same as in Example 1. The resulting autoclaved aerated concrete blocks have a dry density of 451 kg / m³. 3 The compressive strength is 1.7 MPa, which meets the performance test requirements of autoclaved aerated concrete blocks (GB / T 11969-2020).

[0113] The thermal conductivity of Examples 1-6 can be found in [reference]. Figure 7 . Figure 7 These are thermal conductivity diagrams provided in Embodiments 1-6 of the present invention. From... Figure 7 It can be seen that as the amount of aluminum powder increases, the thermal conductivity of the embodiment shows a significant decreasing trend, indicating that the porosity gradually increases, the bubble distribution becomes more uniform, and the thermal insulation performance of the material is significantly improved.

[0114] The method for determining the heat release rate can be found in GB / T 12959-2008 Test Method for Heat of Hydration of Cement (Heat of Solution Method) and GB / T 50080-2016 Standard for Test Method of Performance of Ordinary Concrete Mixtures. In this embodiment, a micro calorimeter (TAM Air isothermal calorimeter) was used to test the heat release rate under constant temperature (25 ± 1℃), and the changes in the heat release rate and cumulative heat release of the sample in the first 72 hours were recorded to analyze the hydration reaction kinetics of the calcium-sodium synergistic excitation system.

[0115] Figure 9 These are the heat release rate curves provided in Embodiments 1-6 of the present invention. From... Figure 9 It can be seen that as the aluminum powder content increases, the peak time of the exothermic rate curves in each embodiment gradually delays, indicating that the hydration reaction rate of the system slows down and the reaction process becomes more stable. This is because the present invention uses... The synergistic activation system, working in conjunction with desulfurized gypsum, facilitates rapid alkalization by NaOH, promoting the dissolution of active silicon and aluminum components from fly ash and slag. Simultaneously, the addition of Ca(OH)₂ and CaSO₄·2H₂O initially generates AFt crystals, delaying the alkalization process. -The consumption of heat makes the exothermic curve of the system more stable, avoiding structural defects caused by early violent exothermic reactions. Compared with the comparative example, the total heat of exothermic reaction of the system of the present invention is significantly increased and the peak time is extended by about 20-40 min, indicating that the hydration reaction is more complete and the product structure is more compact, which is conducive to the formation of a continuous C–(A)–S–H gel network, thereby giving the building blocks higher mechanical strength and stability.

[0116] The kinetic model fitting method for the hydration reaction process is as follows: This embodiment adopts a hydration kinetic model fitting method based on isothermal calorimetry. First, the exothermic rate curve q(t) and cumulative heat release Q(t) of the sample under isothermal conditions are tested using a microcalorimeter, and the degree of hydration α = Q(t) / Q∞ is calculated. Second, based on... The model divides the hydration process into three stages: crystallization nucleation (NG), phase boundary reaction (I), and diffusion control (D). The following equations are used for fitting analysis of each stage:

[0117] NG stage: ;

[0118] Phase I:

[0119] Phase D: .

[0120] The corresponding rate constant K is obtained by fitting the curves of each stage using linear regression or nonlinear least squares method. i And the geometric growth index n, and calculate the activation energy E based on it. α and reaction rate constant The specific principles and steps of this method can be found in the following literature:

[0121] ① Li, Kang, et al. "Hydration heat and kinetics of ternary cementcontaining ultrafine steel slag and blast-furnace slag at elevatedtemperatures." Construction and Building Materials 471 (2025): 140712.

[0122] ② Cui Wenwen, et al. "Study on the hydration kinetics and hydration mechanism of red mud-based cementitious materials." Rock and Soil Mechanics 46.3.

[0123] Figure 10 These are fitting diagrams of the kinetic model of the hydration reaction process provided in Examples 1-6 of this invention, wherein... Figure 10In Figure (a), the kinetic model fitting diagram of the hydration reaction process provided in Examples 1-2 is shown. Figure 10 (b) is a kinetic model fitting diagram of the hydration reaction process provided in Example 3. Figure 10 Figure (c) is a kinetic model fitting diagram of the hydration reaction process provided in Examples 4-6. The hydration reaction processes of Examples 1-6 of the present invention all conform well to the kinetic model fitting diagram. The kinetic fitting law of the model indicates that the calcium-sodium synergistic excitation system has a good regulatory effect on the hydration process of siliceous aluminous solid waste. Among them, Figure 10 The hydration reaction kinetics of Example 3 shown in (b) exhibited the best fitting effect, with smooth curves and high consistency with the theoretical model, and the coefficient of determination R² was greater than 0.99. The reaction rate constants K1 and K3 of this system were significantly higher than those of other examples, indicating that the hydration process was more complete in both the nucleation and diffusion stages. The transition between hydration stages was clear, with rapid reaction in the NG stage, a smooth transition in the I stage, and a moderate duration in the D stage, reflecting a good balance between the hydration product formation rate and the ion diffusion process.

[0124] Comparative Example 1

[0125] An autoclaved aerated concrete block comprises the following raw materials in parts by weight:

[0126] Fly ash: 69 parts, cement: 9.2 parts, lime: 18.35 parts, desulfurized gypsum: 3.2 parts, aluminum powder: 0.175 parts, foam stabilizer: sodium dodecylbenzene sulfonate, 2.5 parts.

[0127] The preparation method of the autoclaved aerated concrete blocks is the same as that in Example 1, with deionized water used for mixing and a water-cement ratio of 0.72.

[0128] The dry density of the obtained autoclaved aerated concrete blocks was 439 kg / m³. 3 The compressive strength is 2.8 MPa.

[0129] Comparative Example 2

[0130] An autoclaved aerated concrete block comprises the following raw materials in parts by weight:

[0131] Fly ash: 66.25 parts, cement: 11 parts, lime: 19 parts, desulfurized gypsum: 3.5 parts, aluminum powder: 0.140 parts, foam stabilizer: sodium dodecylbenzene sulfonate, 2.5 parts.

[0132] The preparation method of the autoclaved aerated concrete blocks is the same as that in Example 1, with deionized water used for mixing and a water-cement ratio of 0.71.

[0133] The dry density of the obtained autoclaved aerated concrete blocks was 439 kg / m³. 3The compressive strength is 2.8 MPa.

[0134] Single-factor experiment:

[0135] In this invention, the dry density, strength and other properties of autoclaved aerated concrete blocks are determined with reference to the standard "Test Methods for Performance of Autoclaved Aerated Concrete" (GB / T 11969-2020).

[0136] Table 2 Aluminum powder dosage ratio in the examples

[0137]

[0138] Table 3 shows the compressive strength, dry density, and thermal conductivity of the examples with different aluminum powder contents.

[0139]

[0140] As can be seen from the table above, aluminum powder has a significant impact on the compressive strength, dry density, and thermal conductivity of autoclaved aerated concrete blocks. The highest compressive strength in Example 3 reached 6.5 MPa, and the oven-dry density was 630 kg / m³. 3 It almost reaches the highest strength of B06 grade, but its oven-dry density is 630 kg / m³. 3 Unable to meet the lightweight requirement, the formula was adjusted to Example 2, which achieved a compressive strength of 5.9 MPa and an oven-dry density of 590 kg / m³. 3 It meets the lightweight requirements of autoclaved aerated concrete and has a thermal conductivity of 0.194 W / (m²). 2 •K), to achieve self-insulating effect.

[0141] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A calcium-sodium synergistically activated silico-aluminate solid waste-based autoclaved aerated concrete block, characterized by, The calcium-sodium synergistically activated silico-aluminous solid waste-based autoclaved aerated concrete block uses fly ash and blast furnace slag as silico-aluminous raw materials, adopts Ca 2+ , Na + synergistically activated system, and uses NaOH and CaO as alkali activators in the activation system. The calcium-sodium synergistic activated silica-alumina solid waste-based autoclaved aerated concrete blocks, by weight, comprise the following components: Fly ash: 25-35 parts, blast furnace slag: 60-80 parts, lime: 5-10 parts, gypsum: 1-5 parts, NaOH: 1-5 parts, aluminum powder: 0.1-0.3 parts, foam stabilizer: 0-5 parts.

2. The calcium-soda synergistically-activated silico-aluminate solid-waste-based autoclaved aerated concrete block according to claim 1, characterized in that, The calcium-sodium synergistic activated silica-alumina solid waste-based autoclaved aerated concrete blocks comprise the following components by weight: Fly ash: 30 parts, blast furnace slag: 70 parts, lime: 8 parts, gypsum: 2 parts, NaOH: 3.5 parts, aluminum powder: 0.150-0.275 parts, foam stabilizer: 0-2.5 parts.

3. The calcium-soda synergistically-activated silico-aluminate solid-waste-based autoclaved aerated concrete block according to claim 1, characterized in that, The gypsum used is desulfurized gypsum; And / or, the NaOH is industrial caustic soda flakes; And / or, the amount of aluminum powder added is 0.175~0.225 parts; And / or, the foam stabilizer is sodium dodecylbenzenesulfonate, and the amount added is 0~2.5 parts.

4. The method of producing a calcium-soda synergistically-activated silico-aluminous solid-waste-based autoclaved aerated concrete block according to any one of claims 1 to 3, characterized in that, The preparation method includes: 1) Dry the fly ash, blast furnace slag, lime, and gypsum; 2) the fly ash, blast furnace slag, lime and gypsum after drying in step 1) and NaOH are mixed according to the ratio and then crushed to obtain a composite mineral powder, wherein the specific surface area of the composite mineral powder is ≥510 m 2 / kg, and D50 is controlled at 12-15 μm; 3) Mix the composite mineral powder obtained in step 2) with the foam stabilizer for the first time, then add water for the second time, and then add aluminum powder foaming agent for the third time. 4) The slurry obtained in step 3) is injected into the mold, and after static gas generation and curing, the calcium-sodium synergistic activated silica-alumina solid waste-based autoclaved aerated concrete block is obtained.

5. The preparation method according to claim 4, characterized in that, In step 1), the drying temperature is 105±5℃, and the drying time is adjusted according to the initial moisture content of the material to ensure that the final moisture content is ≤2%.

6. The preparation method according to claim 4, characterized in that, In step 2), the crushing is performed by adding the material to a ball mill for ball milling. And / or, the D50 of the composite mineral powder is controlled at 13-14 μm; And / or, the process parameters for the ball milling treatment are: ball-to-material ratio of 1:1 to 3:1 or 2:1, rotation speed of 30-50 r / min or 40 r / min, and ball milling time of 20 ± 5 min.

7. The preparation method according to claim 4, characterized in that, In step 3), the first stirring rate is 140±5 r / min, and the stirring time is 1-3 min or 2 min; And / or, the second stirring rate is 285±10 r / min, and the stirring time is 1-5 min or 3 min; And / or, the second stirring is done with warm water at 40-50℃ or 45℃; And / or, the water-cement ratio of the second mixing is controlled at 0.4-0.5 or 0.44; And / or, the third stirring rate is 285±10 r / min, and the stirring time is 10±10 s.

8. The preparation method according to claim 4, characterized in that, In step 4), the settling temperature is 50-60℃, and the gas generation time is 120-140 min; And / or, the curing is autoclaving, with curing conditions of 1-1.5 MPa, 150-200℃ or 1.15 MPa, 180℃, and curing time of 8-10 hours.

9. The application of calcium-sodium synergistically activated silica-alumina solid waste-based autoclaved aerated concrete blocks according to any one of claims 1-3 in the preparation of prefabricated walls.

10. A prefabricated wall system, characterized in that, It includes: The calcium-sodium synergistic activated silica-alumina solid waste-based autoclaved aerated concrete block according to any one of claims 1-3.

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