High-temperature-resistant baking-free brick based on all-solid-waste cementing material and preparation method of high-temperature-resistant baking-free brick

Abstract

The invention relates to a high-temperature-resistant baking-free brick based on an all-solid-waste cementing material and a preparation method of the high-temperature-resistant baking-free brick, and relates to the technical field of building materials. Comprising the following components in parts by weight: 25 parts of an all-solid waste cementing material, 50 parts of recycled concrete aggregate, 20 parts of recycled concrete micro powder, 5-15 parts of rice hull ash, 5-15 parts of waste glass powder and 0.5-3 parts of basalt fiber. Through combination and matching of three systems of rice hull ash, waste glass powder and basalt fiber, all the components form a mullite crystal framework-glass phase filling-fiber bridging multi-stage reinforced structure at high temperature, so that the baking-free brick can keep high normal-temperature strength under the high-temperature condition, and experimental data shows that the baking-free brick has the advantages that the baking-free brick has good application prospects. The compressive strength loss rate of the three-component co-doping system after heat treatment at 1000 DEG C is far lower than that of a single-component system.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to a high-temperature resistant, non-fired brick based on all-solid waste cementitious materials and its preparation method. Background Technology

[0002] With the increasing demands on material performance in high-temperature applications such as industrial kilns and firewalls, traditional cement blocks have revealed significant limitations. Their hydration products primarily rely on low-energy ionic and hydrogen bonds, making them prone to dehydration and volume shrinkage at temperatures above 400℃. This leads to a significant decrease in compressive strength and even safety hazards such as cracking and pulverization. In contrast, geopolymer materials exhibit significant high-temperature resistance advantages. Geopolymer blocks, primarily made from industrial solid wastes such as fly ash and steel slag, have a structure dominated by Si-O-Al and Si-O-Si covalent bonds, forming a stable three-dimensional network structure with bond energies as high as 800-1000 kJ / mol. This unique structure prevents catastrophic damage at high temperatures; instead, it achieves densification through a ceramic transformation process, even exhibiting increased strength in the 800-1000℃ range. Furthermore, geopolymer blocks possess excellent volume stability and crack resistance at high temperatures, providing reliable protection for high-temperature industrial applications.

[0003] In recent years, various modification methods have been explored to further improve the high-temperature performance of geopolymers. For example, adding glass powder can fill the pores of the matrix by utilizing its high-temperature melting characteristics, thus promoting the ceramization process; incorporating ceramic fibers can effectively inhibit crack propagation through bridging; and using aluminum-rich silicon materials can help form the reinforcing phase mullite at high temperatures.

[0004] In related technologies, please refer to Chinese invention patent CN120622940B, which discloses a non-fired refractory brick and its preparation method, including iron tailings, cement, fly ash, functional additives, fine aggregates, quartz sand, chromium aluminum phosphate binder, water-reducing agent, and water. The functional additive is made by using aluminum chloride hexahydrate and alkaline silica sol as raw materials, ammonium molybdate tetrahydrate as catalyst, and growing mullite whiskers on the surface of silicon carbide fibers by vacuum impregnation and heat treatment. The prepared composite silicon carbide fibers are modified with 3-(methacryloyloxy)propyltrimethoxysilane and then copolymerized with acrylic acid and 4-hydroxybutyl vinyl ether. The chromium aluminum phosphate binder is made by using aluminum hydroxide, phosphoric acid, and chromium trioxide as raw materials, and calcium hydroxide as curing agent. The preparation method is relatively complex, and the utilization efficiency of single solid waste is low. The product has good high-temperature resistance but slightly reduced strength. Summary of the Invention

[0005] The purpose of this invention is to address the above-mentioned problems by providing a high-temperature resistant, non-fired brick based on all-solid waste cementitious materials and its preparation method.

[0006] The first aspect of this invention provides a high-temperature resistant, non-fired brick based on all-solid waste cementitious materials, employing the following technical solution:

[0007] A high-temperature resistant, non-fired brick based on all-solid waste cementitious material comprises the following components by weight: 25 parts of all-solid waste cementitious material, 50 parts of recycled concrete aggregate, 20 parts of recycled concrete powder, 5-15 parts of rice husk ash, 5-15 parts of waste glass powder, and 0.5-3 parts of basalt fiber.

[0008] By adopting the above technical solution, rice husk ash, as a highly active siliceous material, has an amorphous SiO2 content of over 90% and a specific surface area exceeding 600 m² / kg. Under high-temperature conditions, the highly active SiO2 can undergo a solid-phase reaction with Al2O3 (mainly derived from solid waste cementitious materials) in the system to generate mullite crystals (3Al2O3·2SiO2) with a needle-like structure. The formation temperature of the mullite phase begins at around 900℃, and its content increases with increasing temperature. These interwoven needle-like crystals form a stable three-dimensional network framework in the matrix, significantly improving the high-temperature stability of the material. However, using it alone reduces the compressive strength. The main components of waste glass powder, SiO2, Na2O, and CaO, begin to melt and form a liquid phase in the temperature range of 800–850℃. This liquid phase has a low viscosity and can effectively wet the surface of solid particles, allowing it to pass through capillary action. The basalt fiber fills the internal pores of the material, promotes the mass transfer process, and accelerates sintering and densification. However, when used alone, it causes volume shrinkage at high temperatures, affecting product stability. Basalt fiber itself has high-temperature resistance. The fiber forms an effective physical overlap through mechanical anchoring and surface friction. When microcracks extend to the vicinity of the fiber, the fiber bears tensile stress through bridging, inhibiting further crack propagation. By combining rice husk ash, waste glass powder, and basalt fiber in a three-system combination, the non-fired bricks can maintain high strength at room temperature under high-temperature conditions. Compared with existing technologies that partially use virgin raw materials, this application achieves 100% utilization of solid waste raw materials, and through the synergistic effect of functional components, it achieves high-value-added utilization of solid waste.

[0009] Preferably, the all-solid waste cementitious material includes slag, fly ash, steel slag, desulfurized gypsum and red mud, and the mass ratio of slag, fly ash, steel slag, desulfurized gypsum and red mud is 12:4:2:1:1.

[0010] Preferably, the particle size of the recycled concrete aggregate is 4.75 to 9 mm.

[0011] Preferably, the specific surface area of ​​the recycled concrete powder is not less than 400 m². 2 / kg.

[0012] Preferably, the specific surface area of ​​the rice husk ash is not less than 600 m². 2 / kg, and the content of amorphous SiO2 is not less than 85%.

[0013] Preferably, the waste glass powder has a particle size D90 ≤ 45 μm and a softening point of 700~800℃.

[0014] Preferably, the basalt fiber has a length of 6-8 mm and a diameter of 13-15 μm.

[0015] By adopting the above technical solution, the specifications and parameters of each component are optimized to improve the overall performance of the non-fired bricks.

[0016] A second aspect of the present invention provides a method for preparing high-temperature resistant, non-fired bricks based on all-solid waste cementitious materials, comprising the following steps:

[0017] S1. Raw material pretreatment: Mix all components of solid waste cementitious material and grind them together. Then grind rice husk ash and recycled concrete powder separately, and screen recycled concrete aggregate, waste glass powder and basalt fiber that meet the particle size requirements.

[0018] S2, Dry Mixing: Dry mix the pretreated solid waste cementitious material, recycled concrete aggregate, recycled concrete powder, rice husk ash and waste glass powder together for 8-12 minutes.

[0019] S3, Fiber dispersion: Add basalt fiber to the dry mix of S2 and continue to dry mix for 3-5 minutes;

[0020] S4. Molding and curing: Add water to the dry mix of S3, wet mix for 8-15 minutes, press and mold, cover and cure for 24 hours after molding, and then naturally cure for 28 days after demolding.

[0021] Preferably, in the above preparation method, in step S1, all components of the solid waste cementitious material are ground together to a specific surface area ≥ 450 m². 2 / kg, rice husk ash is decarbonized by calcination at 650℃ and then ground to a specific surface area greater than or equal to 600 m². 2 / kg, grind recycled concrete powder to a specific surface area ≥400 m² 2 / kg, screen recycled concrete aggregate with a particle size of 4.75-9mm for later use, sieve waste glass powder, collect waste glass powder with D90≤45μm for later use, screen basalt fibers with a length of 5-8mm and a diameter of 13-15μm for later use.

[0022] Preferably, in the above preparation method, the specific step of S4 is as follows:

[0023] S4. Molding and curing: Add water to the dry mix of S3, control the water-to-solid ratio to 0.2, wet mix for 8-15 minutes, then press and mold under 20MPa pressure. After molding, cover with film and cure for 24 hours, and then naturally cure for 28 days after demolding.

[0024] By adopting the above technical solution, after screening the raw materials, the other components except basalt fiber are first dry-mixed and then mixed evenly. After mixing, basalt fiber is added and mixed again to improve the dispersibility of basalt fiber. Finally, water is added for wet mixing, and the water-solid ratio is controlled to improve the quality of the final product. The operation is simple, requires no new equipment, and is easy to promote.

[0025] In summary, this application includes at least one of the following beneficial technical effects:

[0026] 1. By combining rice husk ash, waste glass powder, and basalt fiber into a three-system combination, each component forms a multi-level reinforced structure of mullite crystal skeleton, glass phase filling, and fiber bridging at high temperature. This enables the non-fired bricks to maintain high strength at room temperature under high temperature conditions. Experimental data show that the compressive strength loss rate of the three-component compound system after heat treatment at 1000℃ is much lower than that of the single-component system.

[0027] 2. Compared with existing technologies that partially use virgin raw materials, this application achieves 100% utilization of solid waste raw materials, and through the synergistic combination of functional components, it achieves high-value-added utilization of solid waste. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Modifications or equivalent substitutions made by those skilled in the art based on their understanding of the technical solutions of this invention, without departing from the spirit and scope of the invention, should be covered within the protection scope of this invention.

[0029] The raw materials, reagents and equipment used in the following examples are all commercially available products. Other specific conditions not specified are in accordance with conventional conditions or the manufacturer's recommendations.

[0030] The raw materials used in the embodiments of this application are from the following sources:

[0031] 1. Solid waste cementitious materials: including slag, fly ash, steel slag, desulfurized gypsum and red mud.

[0032] Slag: Originates from steel plants, with a specific surface area of ​​500–600 m². 2 / kg.

[0033] Fly ash: sourced from a power plant, using Grade I or above fly ash, with a silica (SiO2) content of 50-60%, an alumina (Al2O3) content of 25-35%, a loss on ignition of ≤8%, and a particle size mainly distributed in the range of 1-50μm.

[0034] Steel slag: It comes from a steel plant. The converter steel slag is treated by magnetic separation to remove iron. The free calcium oxide (f-CaO) content is ≤3%. The main mineral composition is dicalcium silicate (C2S), tricalcium silicate (C3S), dicalcium ferrite (C2F), etc.

[0035] Desulfurized gypsum: sourced from a power plant, its main component is calcium sulfate dihydrate.

[0036] Red mud: Sourced from Bayer process red mud of an aluminum company, dried using conventional methods, rich in Al2O3 (20-30%), Fe2O3 (25-35%) and Na2O (2-5%).

[0037] 2. Recycled concrete aggregate: derived from construction waste demolished by an environmental protection company.

[0038] 3. Recycled concrete powder: It comes from construction waste demolished by an environmental protection company. The construction waste is crushed, screened and ground by conventional methods. Its main components are hydrated calcium silicate, unhydrated cement particles and fine aggregate.

[0039] 4. Rice husk ash: It is made from rice husks from a rice company. The rice husks are prepared by controlled-temperature combustion (650℃, 2h). The SiO2 content is ≥90%, of which the amorphous SiO2 content is ≥85%. It has a specific surface area (≥600 m² / kg) and abundant mesoporous structure (pore size 2-50nm).

[0040] 5. Waste glass powder: It comes from waste glass bottles and jars recycled by an environmental protection company. The waste glass bottles and jars are cleaned, crushed and ground. The chemical composition is mainly SiO2 (70-75%), Na2O (12-15%) and CaO (8-12%). The softening point is about 700-800℃, the melting temperature range is 800-850℃, and the particle size D90≤45μm.

[0041] 6. Basalt fiber: Purchased commercially.

[0042] The basic chemical composition of the raw materials used in all embodiments of this application is shown in Table 1:

[0043] Table 1. Chemical composition of raw materials (wt%)

[0044] raw material <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> CaO MgO <![CDATA[SO3]]> Loss on ignition slag 35.2 13.5 0.8 41.3 5.2 2.1 1.2 fly ash 52.6 28.3 6.8 3.5 1.2 0.5 3.8 steel slag 18.5 5.2 25.3 40.1 4.8 0.5 2.1 Desulfurized gypsum 3.2 1.1 0.8 38.5 1.2 45.3 8.2 Red mud 11.2 22.5 32.1 15.3 1.5 0.3 12.5 Recycled concrete powder 28.6 8.3 3.2 35.8 2.1 2.8 18.2 Rice husk ash 92.5 1.8 0.6 1.2 0.5 0.2 2.5 Waste glass powder 72.3 1.5 0.5 10.2 3.5 0.2 0.8

[0045] All chemical abbreviations in this application are based on industry-standard usage.

[0046] I. Implementation Examples

[0047] Example 1

[0048] A high-temperature resistant, non-fired brick based on all-solid waste cementitious material comprises the following components by weight: 25 parts of all-solid waste cementitious material, 50 parts of recycled concrete aggregate, 20 parts of recycled concrete powder, 5 parts of rice husk ash, 5 parts of waste glass powder, and 0.5 parts of basalt fiber.

[0049] The solid waste cementitious materials include slag, fly ash, steel slag, desulfurized gypsum, and red mud, with a mass ratio of 12:4:2:1:1. The particle size of the recycled concrete aggregate is 4.75–9 mm. The specific surface area of ​​the recycled concrete powder is ≥400 m² / kg, and the particle size distribution ranges from 1 to 100 μm. The specific surface area of ​​the rice husk ash is ≥600 m² / kg. 2 / kg, and the amorphous SiO2 content is ≥85%; the particle size D90 of the waste glass powder is ≤45μm, and the melting temperature range is 800~850℃; the length of the basalt fiber is 6~8mm, and the diameter is 13~15μm.

[0050] A method for preparing high-temperature resistant, non-fired bricks based on all-solid waste cementitious materials includes the following steps:

[0051] S1. Raw material pretreatment: Mix all components of solid waste cementitious material and grind them together. Then grind rice husk ash and recycled concrete powder separately, and screen recycled concrete aggregate, waste glass powder and basalt fiber that meet the particle size requirements.

[0052] Specifically, slag, fly ash, steel slag, desulfurization gypsum, and red mud are mixed and ground together until the specific surface area is ≥450m². 2 / kg, rice husk ash is calcined at 650℃ for 1 hour to remove carbon, and then ground until the specific surface area is greater than or equal to 600 m². 2 / kg, grind recycled concrete powder to a specific surface area ≥400 m² 2 / kg, screen recycled concrete aggregate with a particle size of 4.75-9mm for later use, sieve waste glass powder, collect waste glass powder with D90≤45μm for later use, screen basalt fibers with a length of 5-8mm and a diameter of 13-15μm for later use.

[0053] S2, Dry Mixing: Add the pretreated solid waste cementitious material, recycled concrete aggregate, recycled concrete powder, rice husk ash and waste glass powder to the mixer and dry mix for 8 minutes.

[0054] S3, Fiber dispersion: Add basalt fiber to the dry mix of S2 and continue to dry mix for 3 minutes;

[0055] S4. Molding and Curing: Add water to the dry mix in S3, and control the water-to-solid ratio to be 0.2. Here, the water-to-solid ratio refers to the ratio between the amount of water added and the total amount of solids. After wet mixing for 8 minutes, a slurry is formed. The slurry is injected into a mold and pressed into shape under a pressure of 20 MPa. The molded blocks are covered with a film and cured at room temperature for 24 hours before demolding. After demolding, the blocks are placed in a natural environment for natural curing for 28 days to obtain high-temperature resistant non-fired bricks based on all-solid waste cementitious materials.

[0056] Example 2

[0057] A high-temperature resistant, non-fired brick based on all-solid waste cementitious material comprises the following components by weight: 25 parts of all-solid waste cementitious material, 50 parts of recycled concrete aggregate, 20 parts of recycled concrete powder, 5 parts of rice husk ash, 15 parts of waste glass powder, and 3 parts of basalt fiber, wherein the specifications of each component are the same as in Example 1.

[0058] The preparation method of the high-temperature resistant non-fired bricks based on all-solid waste cementitious materials is the same as that in Example 1.

[0059] Example 3

[0060] A high-temperature resistant, non-fired brick based on all-solid waste cementitious material comprises the following components by weight: 25 parts of all-solid waste cementitious material, 50 parts of recycled concrete aggregate, 20 parts of recycled concrete powder, 15 parts of rice husk ash, 5 parts of waste glass powder, and 3 parts of basalt fiber, wherein the specifications of each component are the same as in Example 1.

[0061] The preparation method of the high-temperature resistant non-fired bricks based on all-solid waste cementitious materials is the same as that in Example 1.

[0062] Example 4

[0063] A high-temperature resistant, non-fired brick based on all-solid waste cementitious material comprises the following components by weight: 25 parts of all-solid waste cementitious material, 50 parts of recycled concrete aggregate, 20 parts of recycled concrete powder, 15 parts of rice husk ash, 15 parts of waste glass powder, and 0.5 parts of basalt fiber, wherein the specifications of each component are the same as in Example 1.

[0064] The preparation method of the high-temperature resistant non-fired bricks based on all-solid waste cementitious materials is the same as that in Example 1.

[0065] Example 5

[0066] A high-temperature resistant, non-fired brick based on all-solid waste cementitious material comprises the following components by weight: 25 parts of all-solid waste cementitious material, 50 parts of recycled concrete aggregate, 20 parts of recycled concrete powder, 10 parts of rice husk ash, 10 parts of waste glass powder, and 1.5 parts of basalt fiber, wherein the specifications of each component are the same as in Example 1.

[0067] The preparation method of the high-temperature resistant non-fired bricks based on all-solid waste cementitious materials is the same as that in Example 1.

[0068] Example 6

[0069] A high-temperature resistant, non-fired brick based on all-solid waste cementitious material comprises the following components by weight: 25 parts of all-solid waste cementitious material, 50 parts of recycled concrete aggregate, 20 parts of recycled concrete powder, 10 parts of rice husk ash, 15 parts of waste glass powder, and 1.5 parts of basalt fiber, wherein the specifications of each component are the same as in Example 1.

[0070] The preparation method of the high-temperature resistant non-fired bricks based on all-solid waste cementitious materials is the same as that in Example 1.

[0071] Example 7

[0072] A high-temperature resistant, non-fired brick based on all-solid waste cementitious material comprises the following components by weight: 25 parts of all-solid waste cementitious material, 50 parts of recycled concrete aggregate, 20 parts of recycled concrete powder, 10 parts of rice husk ash, 10 parts of waste glass powder, and 3 parts of basalt fiber, wherein the specifications of each component are the same as in Example 1.

[0073] The preparation method of the high-temperature resistant non-fired bricks based on all-solid waste cementitious materials is the same as that in Example 1.

[0074] Example 8

[0075] A high-temperature resistant, non-fired brick based on all-solid waste cementitious material comprises the following components by weight: 25 parts of all-solid waste cementitious material, 50 parts of recycled concrete aggregate, 20 parts of recycled concrete powder, 15 parts of rice husk ash, 10 parts of waste glass powder, and 1.5 parts of basalt fiber, wherein the specifications of each component are the same as in Example 1.

[0076] The preparation method of the high-temperature resistant non-fired bricks based on all-solid waste cementitious materials is the same as that in Example 1.

[0077] II. Comparative Example

[0078] Comparative Example 1

[0079] A non-fired brick, which differs from Example 1 in that it does not contain rice husk ash, waste glass powder and basalt fiber, and comprises the following components by weight: 25 parts of all-solid waste cementitious material, 50 parts of recycled concrete aggregate, and 20 parts of recycled concrete powder.

[0080] The preparation method is the same as in Example 1, except that the treatment of rice husk ash, waste glass powder and basalt fiber is removed, which will not be described in detail here.

[0081] Comparative Example 2

[0082] A non-fired brick, which differs from Example 5 in that it does not contain basalt fiber, comprises the following components by weight: 25 parts of solid waste cementitious material, 50 parts of recycled concrete aggregate, 20 parts of recycled concrete powder, 10 parts of rice husk ash, and 10 parts of waste glass powder.

[0083] The preparation method is basically the same as in Example 5, except that the step of treating basalt fibers is removed, which will not be described in detail here.

[0084] Comparative Example 3

[0085] A non-fired brick, which differs from Example 5 in that it does not contain rice husk ash and waste glass powder, and comprises the following components by weight: 25 parts of solid waste cementitious material, 50 parts of recycled concrete aggregate, 20 parts of recycled concrete powder, and 1.5 parts of basalt fiber.

[0086] The preparation method is basically the same as in Example 5, except that the treatment steps for rice husk ash and waste glass powder are removed, which will not be described in detail here.

[0087] Comparative Example 4

[0088] A non-fired brick, which differs from Example 5 in that it does not contain waste glass powder, and comprises the following components by weight: 25 parts of solid waste cementitious material, 50 parts of recycled concrete aggregate, 20 parts of recycled concrete powder, 10 parts of rice husk ash, and 1.5 parts of basalt fiber.

[0089] The preparation method is basically the same as in Example 5, except that the step of treating waste glass powder is removed, which will not be described in detail here.

[0090] III. Performance Test Experiments and Results

[0091] The performance of the non-fired bricks prepared in Examples 1-8 and Comparative Examples 1-4 were tested respectively.

[0092] Test method: Prepare and cure the specimens in accordance with the provisions of GB / T 2542-2012 "Test Methods for Masonry Bricks" regarding specimen preparation, curing, dimensional measurement and compressive strength test.

[0093] For each embodiment and comparative example, no less than 6 unfired bricks were sampled, with dimensions of 240 mm × 115 mm × 53 mm. After demolding for 24 hours, they were cured at (20±2) ℃ and (60±5) % relative humidity for 28 days. Before the test, they were dried in a forced-air drying oven at (105±5) ℃ until the mass was constant and cooled to room temperature for use.

[0094] According to the method for determining the dry mass in GB / T 2542-2012, the initial mass of the sample was weighed and recorded as m0 (accurate value 0.01g). The sample was placed in an electric resistance furnace and heated to 25 ℃ (room temperature control), 400 ℃, 800 ℃ and 1000 ℃ respectively, with a heating rate of about 5 ℃ / min. It was held at the target temperature for 2 h, and then cooled to room temperature with the furnace. After brushing off the surface dust, the mass m1 after high temperature treatment was weighed.

[0095] The mass loss rate of the sample at different temperatures is calculated using the following formula:

[0096]

[0097] Where m0 is the mass of the sample before high-temperature treatment, and m1 is the mass of the sample after high-temperature treatment at the corresponding temperature. At least 3 samples are tested for each formulation, and the arithmetic mean is taken as the mass loss rate of that formulation at the corresponding temperature, with the result rounded to one decimal place.

[0098] The test results are shown in Table 2:

[0099] Table 2. Mass loss rate (%) of various non-fired bricks at different temperatures

[0100] temperature 25℃ 400℃ 800℃ 1000℃ Example 1 0 2.1 5.8 8.9 Example 2 0 1.8 4.9 7.2 Example 3 0 2 5.2 7.8 Example 4 0 1.9 5 7.5 Example 5 0 1.2 3.5 5.1 Example 6 0 1.3 3.8 5.8 Example 7 0 1.4 3.7 5.3 Example 8 0 1.5 4.1 5.9 Comparative Example 1 0 3.2 8.1 12.5 Comparative Example 2 0 1.5 4.2 6.2 Comparative Example 3 0 1.7 4.5 6.8 Comparative Example 4 0 1.8 5.5 8.2

[0101] The compressive strength test before and after high temperature treatment was conducted according to the specifications for compressive strength test in GB / T 4111-2013. The untreated samples were subjected to compressive strength tests at 25 ℃ to obtain the compressive strength f of each proportion of the non-fired bricks. 25 As a reference strength, at least 6 specimens should be prepared for each mix proportion, and the compressive strength of a single specimen should be calculated using the following formula:

[0102]

[0103] in, The failure load of the specimen is (N). The area under pressure (mm²) is the compressive strength. The arithmetic mean of the strengths of each specimen is taken as the compressive strength of this mix at 25 °C.

[0104] The samples were treated at different temperatures (400 ℃, 800 ℃, and 1000 ℃) and then cooled to room temperature in the furnace. Compressive strength tests were then conducted using the same method to obtain the compressive strength at the corresponding temperatures. (T represents the corresponding temperature). For each mix proportion and at each temperature, no fewer than 3 samples should be taken, and the arithmetic mean should be used as the compressive strength at that temperature.

[0105] The compressive strength f at 25℃ 25As a benchmark, the compressive strength loss rate after high temperature is calculated using the following formula:

[0106]

[0107] The test results are shown in Table 3:

[0108] Table 3. Compressive strength loss rate (%) of various non-fired bricks at different temperatures

[0109] temperature 25℃ 400℃ 800℃ 1000℃ Example 1 0 12.3 35.6 58.4 Example 2 0 10.5 28.3 45.6 Example 3 0 11.8 31.5 49.2 Example 4 0 11.2 29.8 46.3 Example 5 0 7.2 18.5 26.3 Example 6 0 7.8 20.1 29.5 Example 7 0 8.9 21.3 28.1 Example 8 0 9.2 22.8 30.2 Comparative Example 1 0 18.5 52.3 78.2 Comparative Example 2 0 8.5 23.6 35.8 Comparative Example 3 0 11 32.5 48.5 Comparative Example 4 0 10.2 30.8 42.1

[0110] The appearance inspection of the samples shall be carried out in accordance with the relevant provisions of GB / T 2542-2012 and GB / T 4111-2013 on appearance quality inspection. After the holding time at each temperature is completed and the samples are cooled to room temperature with the furnace, the samples shall be taken out and observed visually under natural diffused light. The observation shall include: whether the sample is intact, whether there are any missing corners or edges; whether there are any cracks and their number, width and penetration; and whether there are any phenomena such as surface powdering, sintering, softening, bulging, or peeling.

[0111] Based on the above phenomena, the surface condition of the samples is qualitatively described and classified. At least three samples of each formulation are examined at the same temperature, and a typical surface condition description for that formulation at that temperature is given based on the observations of all samples.

[0112] The test results are shown in Table 4:

[0113] Table 4 Surface state of various unfired bricks at different temperatures

[0114] temperature 25℃ 400℃ 800℃ 1000℃ Example 1 whole intact Slight powdering Local damage Example 2 whole intact Surface sintering Partial glazing Example 3 whole intact Good sintering Localized glazing Example 4 whole intact Dense sintering Uniform glazing Example 5 Dense and uniform intact Dense sintering Uniform glazing Example 6 Dense and uniform intact Dense sintering slight deformation Example 7 Fiber aggregation intact Dense sintering Uniform glazing Example 8 Slightly loose intact Good sintering Uniform glazing Comparative Example 1 whole microcracks Severe pulverization Structural damage Comparative Example 2 Dense and uniform intact Dense sintering Localized glazing, micro-cracks Comparative Example 3 whole intact Surface sintering Uneven glazing with cracks Comparative Example 4 whole intact Sintered Porous Unglazed, with micro-cracks

[0115] As shown in Tables 2-4, below 400℃, the main phenomenon is the removal of physical water and bound water, with a mass loss rate between 1.2% and 3.2%. The strength loss mainly stems from the initial decomposition of hydration products. Among them, Example 5 performed best, with a mass loss rate of 1.2% and a strength loss rate of 7.2%. At 800℃, the material undergoes a significant phase transformation. Comparative Example 1 suffers a strength loss of over 50% due to the lack of functional components, while Example 5, through the mullite formation reaction promoted by rice husk ash and the liquid-phase sintering of glass powder to form a stable ceramic structure, controls the strength loss rate at 18.5%. At a high temperature of 1000℃, the synergistic effect is particularly significant. Example 5 forms a uniform glaze layer on the surface, with a mass loss rate of only 5.1% and a strength loss rate of 26.3%, which is far superior to other examples.

[0116] The analysis of the synergistic effect of the components showed that the three-component compound system had a significant synergistic enhancement effect: compared with Example 1 and Example 5, the strength loss rate at 1000℃ decreased from 58.4% to 26.3%; the results of Example 2 showed that the performance deteriorated significantly when the amount of rice husk ash was insufficient (strength loss rate of 45.6%), confirming that the active SiO2 provided by it is the basis for the formation of mullite; the comparison between Comparative Example 2 (without fiber) and Example 5 further proved that the fiber plays a key role in inhibiting the propagation of microcracks.

[0117] Ultimately, Example 5 (10 parts rice husk ash, 10 parts glass powder, and 1.5 parts fiber) was determined to be the optimal ratio, which exhibits excellent comprehensive performance across the entire temperature range: room temperature strength of 36.8 MPa, strength retention rate of 73.7% after heat treatment at 1000℃, mass loss rate of 5.1%, and a complete glaze protective layer is formed on the surface, making it the optimal embodiment of this application.

[0118] In summary, compared with existing technologies that partially utilize virgin raw materials, this application achieves 100% utilization of solid waste raw materials and realizes high-value utilization of solid waste through the synergistic combination of functional components. The rice husk ash-waste glass powder-basalt fiber three-system combination provided by this application fully utilizes the active silicon source characteristics of rice husk ash, the high-temperature melting characteristics of glass powder, and the toughening characteristics of fiber, achieving a breakthrough in material performance. Experimental data shows that the compressive strength loss rate of the three-component compound system after heat treatment at 1000℃ is much lower than that of the single-component system. While maintaining high room temperature strength, it achieves excellent high-temperature performance and is suitable for high-temperature environments such as industrial kiln linings, firewalls, chimneys, and other structures.

Claims

1. A high-temperature resistant, non-fired brick based on all-solid waste cementitious material, characterized in that: It includes the following components by weight: 25 parts of solid waste cementitious material, 50 parts of recycled concrete aggregate, 20 parts of recycled concrete powder, 5-15 parts of rice husk ash, 5-15 parts of waste glass powder, and 0.5-3 parts of basalt fiber.

2. The high-temperature resistant, non-fired brick based on all-solid waste cementitious material according to claim 1, characterized in that: The solid waste cementitious material includes slag, fly ash, steel slag, desulfurized gypsum, and red mud, and the mass ratio of the slag, fly ash, steel slag, desulfurized gypsum, and red mud is 12:4:2:1:

1.

3. The high-temperature resistant, non-fired brick based on all-solid waste cementitious material according to claim 1, characterized in that: The particle size of the recycled concrete aggregate is 4.75–9 mm.

4. The high-temperature resistant, non-fired brick based on all-solid waste cementitious material according to claim 1, characterized in that: The specific surface area of ​​the recycled concrete powder is not less than 400 m². 2 / kg.

5. The high-temperature resistant, non-fired brick based on all-solid waste cementitious material according to claim 1, characterized in that: The specific surface area of ​​the rice husk ash is not less than 600 m². 2 / kg, and the content of amorphous SiO2 is not less than 85%.

6. The high-temperature resistant, non-fired brick based on all-solid waste cementitious material according to claim 1, characterized in that: The waste glass powder has a particle size D90≤45μm and a softening point of 700~800℃.

7. The high-temperature resistant, non-fired brick based on all-solid waste cementitious material according to claim 1, characterized in that: The basalt fibers are 6–8 mm in length and 13–15 μm in diameter.

8. A method for preparing high-temperature resistant, non-fired bricks based on all-solid waste cementitious materials according to any one of claims 1-7, characterized in that: Includes the following steps: S1. Raw material pretreatment: Mix all components of solid waste cementitious material and grind them together. Then grind rice husk ash and recycled concrete powder separately, and screen recycled concrete aggregate, waste glass powder and basalt fiber that meet the particle size requirements. S2, Dry Mixing: Dry mix the pretreated solid waste cementitious material, recycled concrete aggregate, recycled concrete powder, rice husk ash and waste glass powder together for 8-12 minutes. S3, Fiber dispersion: Add basalt fiber to the dry mix of S2 and continue to dry mix for 3-5 minutes; S4. Molding and curing: Add water to the dry mix of S3, wet mix for 8-15 minutes, press and mold, cover and cure for 24 hours after molding, and then naturally cure for 28 days after demolding.

9. The preparation method according to claim 8, characterized in that: In S1, all components of the solid waste cementitious material are ground together to a specific surface area ≥ 450 m². 2 / kg, rice husk ash is decarbonized by calcination at 650℃ and then ground to a specific surface area greater than or equal to 600 m². 2 / kg, grind recycled concrete powder to a specific surface area ≥400 m² 2 / kg, screen recycled concrete aggregate with a particle size of 4.75-9mm for later use, sieve waste glass powder, collect waste glass powder with D90≤45μm for later use, screen basalt fibers with a length of 5-8mm and a diameter of 13-15μm for later use.

10. The preparation method according to claim 8, characterized in that: S4. Molding and curing: Add water to the dry mix of S3, control the water-to-solid ratio to 0.2, wet mix for 8-15 minutes, then press and mold under 20MPa pressure. After molding, cover with film and cure for 24 hours, and then naturally cure for 28 days after demolding.

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