River channel sediment combined with multi-source industrial waste slag non-fired brick and preparation method and application

Abstract

The application discloses a kind of river channel sediment combined multi-source industrial waste slag's non-burned brick and preparation method and application.The present application takes river channel sediment as core, combines more than five kinds of industrial waste slag such as steel slag, red mud, desulfurization gypsum, blast furnace slag, fly ash, each component is formed by scientific proportioning, and the synergic system of "mud matrix-calcium excitation-sulfate excitation-cementing enhancement" is formed, the complementary advantages of multi-source solid waste are fully exerted.The bulk of various solid wastes is realized, and high-value utilization, and the total amount of solid waste can reach more than 80%.

Description

Technical Field

[0001] This invention relates to the fields of solid waste resource utilization and green building materials technology, and in particular to a non-fired brick made from riverbed sediment combined with multi-source industrial waste residue, its preparation method and application. Background Technology

[0002] With the continuous advancement of urbanization and the increasing efforts in water environment management in my country, river dredging projects have been widely carried out nationwide, generating massive amounts of river sediment. This sediment typically consists of clay minerals, organic matter, nitrogen and phosphorus nutrients, and potentially heavy metal pollutants. Traditional methods of sediment disposal mainly involve stockpiling or landfilling, which not only occupies a large amount of land resources but also easily causes secondary pollution of groundwater and surrounding soil through leachate. Furthermore, pollutants in the sediment may re-enter water bodies with rainwater runoff, leading to the re-emergence of black and foul-smelling water. Therefore, the reduction, harmless treatment, and resource recovery of river sediment have become urgent environmental issues that need to be addressed.

[0003] Meanwhile, as a major industrial country, my country generates a large amount of industrial solid waste every year. Steel slag, a waste product generated during steelmaking, accounts for approximately 15-20% of crude steel production, and its current stockpiles are enormous. Steel slag contains free calcium oxide, which expands in volume upon hydration, limiting its large-scale application in building materials. Red mud, a highly alkaline waste product generated during alumina production, produces approximately 1.0-1.8 tons of red mud per ton of alumina produced; its high alkalinity and fine particle characteristics pose a serious threat to the ecological environment. Desulfurization gypsum, a byproduct of flue gas desulfurization in coal-fired power plants, is mainly composed of calcium sulfate dihydrate, but often contains impurities such as calcium sulfite, affecting its resource utilization. Blast furnace slag, a waste product generated during ironmaking, possesses potential hydraulic properties, but requires activation to fully realize its cementing properties. Fly ash, a fine ash emitted from coal-fired power plants, has a slow activation rate. The large-scale stockpiling of these industrial wastes not only occupies land but also poses environmental risks.

[0004] Non-fired bricks, as a type of green building material, use industrial waste, construction waste, tailings, etc. as the main raw materials. They are formed through physical and chemical processes without high-temperature sintering. They have the advantages of low energy consumption, low pollution, and high waste utilization rate, and are an important way to realize the resource utilization of solid waste.

[0005] Existing technologies have reported several methods for preparing non-fired bricks using bottom sediment or industrial waste. For example, patent CN115286332A discloses a method for preparing non-fired bricks using steel slag and blast furnace slag. By controlling the particle size, moisture content, and mixing process of the steel slag, non-fired bricks with a certain strength are obtained. However, the raw material system is relatively simple and does not involve the utilization of bottom sediment. Patent CN114772883A discloses a method for treating bottom sediment from black and odorous water bodies and its application in the preparation of non-fired bricks. It uses a combination of methods such as ultrasonic cracking, hydrated calcium silicate stabilization, and microbial degradation to treat the bottom sediment. The process is complex and costly. Patent CN117550839A discloses a method for preparing non-fired bricks using semi-dry desulfurization ash. This method involves activating red mud slurry and reacting it with desulfurization ash, followed by oxygen steam curing to promote the conversion of calcium sulfite. However, this method requires a large amount of red mud and mainly targets desulfurization ash. Patent CN118063188A discloses a whole solid waste carbonization curing non-fired brick, which uses steel slag, coal gangue and fly ash to prepare non-fired bricks through pre-curing and carbonization curing, demonstrating the advantages of carbonization curing, but does not involve bottom mud.

[0006] In summary, the existing technologies have the following shortcomings: 1) There is a lack of systematic technical solutions that combine riverbed sediment with various industrial wastes for synergistic utilization; 2) There is a lack of effective means to stabilize potential heavy metals in the sediment in the long term; 3) The physicochemical synergistic effect among various solid wastes has not been fully utilized; 4) The early strength, freeze-thaw resistance and other durability properties of the non-fired bricks need to be further improved; 5) The preparation process is complex or costly, which is not conducive to large-scale promotion. Summary of the Invention

[0007] The purpose of this invention is to address the technical deficiencies in the existing technology by providing a method for preparing non-fired bricks made from riverbed sediment combined with multi-source industrial waste.

[0008] Another object of the present invention is to provide non-fired bricks obtained by the above preparation method.

[0009] Another object of the present invention is to provide the application of the above-mentioned non-fired bricks in walls, roads, slope protection and non-load-bearing walls of buildings.

[0010] The technical solution adopted to achieve the purpose of this invention is: A method for preparing non-fired bricks using riverbed sediment combined with multi-source industrial waste includes the following steps: Step 1: Riverbed sediment with a moisture content ≤60% is dewatered, screened to remove impurities, and then activated to obtain activated sediment. Riverbed sediment is used as the main substrate and is rich in SiO₂. And Al O This forms the basis for the formation of gel products. Activation treatment disrupts the mineral lattice in the sediment, releasing active silica and aluminum, thus creating conditions for subsequent reactions. Step 2: The steel slag is cooled, selected for iron, screened and ground to obtain steel slag powder with a particle size ≤0.08mm; Step 3: Dry and grind the red mud, desulfurized gypsum, blast furnace slag and fly ash respectively to obtain red mud powder, desulfurized gypsum powder, blast furnace slag powder and fly ash with a particle size ≤0.08mm respectively. Step 4: By weight, take 100 parts of activated bottom mud obtained in Step 1, 10-30 parts of steel slag powder obtained in Step 2, 5-20 parts of red mud powder obtained in Step 3, 3-10 parts of desulfurized gypsum powder, 10-25 parts of blast furnace slag powder, 5-15 parts of fly ash, 2-10 parts of composite activator, and 10-25 parts of water, mix them evenly to obtain a mixture. Step 5: Place the mixture obtained in Step 4 into a mold, press it under a pressure of 15-25 MPa, hold the pressure for 10-30 seconds, and obtain a brick blank; Step 6: Cur the brick blanks obtained in Step 5 at a temperature of 20-30℃ and a humidity of ≥90% for 7-28 days to obtain non-fired bricks.

[0011] In the above technical solution, in step 1, the activation treatment is a mechanical-chemical coupling activation; the dewatered and screened riverbed sediment is mixed with an activator at a mass ratio of 1:(0.1-0.3), and ball-milled for 1-3 hours until the particle size of the mixture is ≤0.08mm; the activator is one or more of shell powder, quicklime, or carbide slag. Mechanical activation through ball milling can refine the particles and disrupt the crystal lattice; the CaO introduced by the activator can react with the active SiO in the sediment. And Al O The reaction produces a small amount of hydration products, while simultaneously increasing the alkalinity of the system.

[0012] In the above technical solution, in step 2, the cooling time of the steel slag is ≥24h, the total iron content of the steel slag after iron selection is 0.5-1.0 wt%, and the moisture content of the steel slag undersize is ≤0.2 wt%. Strictly controlling the free iron oxide and moisture in the steel slag is beneficial to improving its stability and activity.

[0013] In the above technical solution, in step 3, the red mud contains 2-5 wt% sodium oxide, 20-30 wt% alumina, and 20-30 wt% iron oxide; the desulfurized gypsum contains ≥85 wt% calcium sulfate dihydrate; the blast furnace slag contains 13-15 wt% titanium dioxide; and the fly ash is Grade I or Grade II fly ash. The key components of each industrial waste residue are defined to ensure their synergistic effect.

[0014] In the above technical solution, in step 4, the composite activator is a mixture of an alkali activator and a salt activator, with a mass ratio of (2-4):1; the alkali activator is one or more of water glass, sodium hydroxide, and potassium hydroxide; the salt activator is one or more of sodium sulfate, sodium carbonate, and sodium aluminate.

[0015] In the above technical solution, in step 4, the mixing adopts a step-by-step mixing method: first, the activated bottom mud, steel slag powder, red mud powder, desulfurized gypsum powder, blast furnace slag powder and fly ash are dry mixed for 2-5 minutes, and then the composite activator and water are added for wet mixing for 5-10 minutes to ensure that the materials are mixed evenly.

[0016] In the above technical solution, step 6 involves curing in a standard curing room with daily water spraying for moisture retention; or pre-curing for 12-48 hours at a temperature of 20-30℃ and a relative humidity of 40%-70%, followed by standard curing. Pre-curing helps drain excess moisture, preventing cracking of the brick, while subsequent standard curing promotes full hydration.

[0017] Another aspect of the present invention includes that the unfired bricks obtained by the preparation method have a 28-day compressive strength ≥20MPa, a flexural strength ≥4.5MPa, a water absorption rate ≤12%, and a strength loss rate ≤15% after 25 freeze-thaw cycles.

[0018] On the other hand, it also includes the application of the unfired bricks in walls, roads, slope protection and non-load-bearing walls of buildings.

[0019] Compared with the prior art, the beneficial effects of the present invention are: (1) Large solid waste disposal capacity and significant synergistic effect: This invention takes riverbed sediment as the core and combines more than five kinds of industrial waste residues such as steel slag, red mud, desulfurization gypsum, blast furnace slag, and fly ash. The steel slag powder contains C S, C S and f-CaO serve as both gelling components and alkali activators, providing the system with alkalinity and calcium source. During curing, f-CaO hydrates to form Ca(OH)₂. It can further participate in volcanic ash reactions or carbonization reactions. The strong alkalinity of red mud powder can provide OH- to the system. This promotes the activation of slag and sediment; simultaneously, the active Al in the red mud... O and Fe O Can be used with Ca² The reaction produces cementitious products such as hydrated calcium aluminate and calcium aluminoferrite, which improve the strength of the bricks. Desulfurized gypsum powder provides SO₂. ² It can react with hydrated calcium aluminate to form ettringite (AFt), and the formation of ettringite can significantly improve the early strength and impermeability of bricks. Meanwhile, the CaSO₄ in desulfurized gypsum... It can also be used as a sulfate activator. Blast furnace slag powder has potential hydraulic properties and can rapidly hydrate to form CSH gel under alkaline conditions, which is a major contributor to later-stage strength. Its high Al content... O The content also facilitates the synergistic formation of AFt with gypsum. The pozzolanic activity of fly ash continues to exert its effect in the later stages, improving the long-term strength and durability of the brick, as well as its workability and crack resistance. The addition of the composite activator further enhances the activating effect on siliceous aluminosilicate materials such as slag, sediment, and fly ash, accelerating the hydration reaction process. The alkali activator provides OH... Disruption of the vitreous structure; salt activator provides SO ² These components participate in the formation of AFt or accelerate hydration. Through scientific formulation, a synergistic system of "sediment matrix - calcium activation - sulfate activation - cementation enhancement" is formed, fully leveraging the complementary advantages of multi-source solid waste. This enables the large-scale and high-value utilization of various solid wastes, with the total solid waste content reaching over 80%.

[0020] (2) Multiple activation and stimulation, and full hydration reaction: Through multiple means such as mechanical-chemical coupling to activate the bottom sediment, alkalinity provided by alkaline solid waste, and sulfate activation, the potential activity of various silicon-aluminum raw materials is released to the maximum extent, which promotes the generation of hydration products such as CSH gel and AFt, laying the foundation for high-intensity development.

[0021] (3) Excellent product performance and broad application prospects: The non-fired bricks prepared by this invention have a compressive strength of more than 20MPa after 28 days, and some formulas can reach 30MPa. The flexural strength is more than 4.5MPa. The water absorption rate is low and the frost resistance is good. All performance indicators far exceed the requirements of the national standard MU15. They can be widely used in the fields of walls, roads, slope protection, and non-load-bearing walls of buildings.

[0022] (4) The process is simple and easy to promote: The preparation method of the present invention has a clear process, strong adaptability to existing brick making equipment, wide range of raw material sources, low cost, and is easy to carry out large-scale industrial production and promotion in the building materials industry, with significant economic and social benefits. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0024] In the following examples, unless otherwise specified, all raw materials used are commercially available products or processed using conventional methods. The chemical composition of each main raw material is shown in Tables 1 and 2.

[0025] Table 1 Chemical composition (wt%) of riverbed sediment and activator (shell powder)

[0026] Table 2 Chemical composition (wt%) of industrial waste residue

[0027] Note: The "Other" category of desulfurized gypsum in Table 2 mainly consists of water of crystallization and a small amount of calcium sulfite; the "Other" category of fly ash mainly consists of unburned carbon.

[0028] Example 1 A method for preparing non-fired bricks using riverbed sediment combined with multi-source industrial waste includes the following steps: Step 1, Pretreatment of riverbed sediment: Dewater the riverbed sediment to a moisture content of 55%, pass it through a 5mm sieve to remove debris such as branches and plastics, take 100kg of the dry sediment from the sieve, mix it with 20kg of shell powder, place it in a planetary ball mill, and ball mill it at 500r / min for 2h until the particle size of the mixture is ≤0.08mm, thus obtaining activated sediment.

[0029] Step 2, steel slag pretreatment: Take steel slag from a steel plant converter, and after open-air stacking and cooling for ≥24 hours, perform multi-stage magnetic separation until the total iron content is 0.7%, then crush and screen, take the sieve material with a particle size ≤1.5mm, grind it with a ball mill until the particle size is ≤0.08mm and the moisture content is 0.15%, to obtain steel slag powder.

[0030] Step 3, Pretreatment of other industrial waste residues: Red mud, desulfurized gypsum, blast furnace slag and fly ash are dried and ground respectively to obtain red mud powder, desulfurized gypsum powder, blast furnace slag powder and fly ash with a particle size ≤0.08mm.

[0031] Step 4, Mixing and Molding: By weight: 100 parts activated bottom mud, 20 parts steel slag powder, 12 parts red mud powder, 6 parts desulfurized gypsum powder, 15 parts blast furnace slag powder and 10 parts fly ash are added to a forced mixer and dry-mixed for 3 minutes. Then, 6 parts of composite activator are dissolved in 18 parts of water and added to the mixer. Wet mixing is continued for 5 minutes to obtain the mixture. The composite activator is water glass (modulus 1.5, solid content 35%) and industrial grade sodium sulfate are mixed at a mass ratio of 3:1.

[0032] Step 5, pressing and molding: The mixture is loaded into a 240mm×115mm×53mm mold in two batches, placed on a press, and pressed and molded at 20MPa pressure for 15s. The mold is then demolded to obtain the brick blank.

[0033] Step 6, Curing: Cur the brick blanks in a standard curing room at 20℃ and 95% humidity for 28 days, spraying water daily to maintain moisture. The resulting unfired brick is designated S1.

[0034] Example 2 A method for preparing non-fired bricks using riverbed sediment combined with multi-source industrial waste includes the following steps: This embodiment is basically the same as Embodiment 1, except that the proportions of some raw materials are adjusted in step 4: 100 parts activated bottom mud, 25 parts steel slag powder, 8 parts red mud powder, 5 parts desulfurized gypsum powder, 18 parts blast furnace slag powder, 8 parts fly ash, 5 parts composite activator, and 16 parts water. The remaining steps are the same as in Embodiment 1, resulting in non-fired bricks, denoted as S2.

[0035] Example 3 A method for preparing non-fired bricks using riverbed sediment combined with multi-source industrial waste includes the following steps: This embodiment is basically the same as Embodiment 1, except that in step 1, no shell powder is added during the pretreatment of the riverbed sediment; instead, the sediment is ball-milled separately to the same fineness. The remaining steps are the same as in Embodiment 1, resulting in non-fired bricks, denoted as S2.

[0036] Example 4 This embodiment is basically the same as Embodiment 1, except that the curing method in step 6 is changed to: first, pre-curing at 25℃ and 60% relative humidity for 24 hours, and then standard curing for 28 days. The remaining steps are the same as in Embodiment 1, resulting in non-fired bricks, denoted as S2.

[0037] Comparative Example 1 A method for preparing non-fired bricks includes the following steps: The method used in this comparative example is basically the same as that in Example 1, except that no red mud is added in step 3 and no red mud powder is added in step 4; the missing parts are made up by an equal amount of blast furnace slag powder. The remaining steps are the same as in Example 1, and the resulting sample is denoted as D1.

[0038] Comparative Example 2 A method for preparing non-fired bricks includes the following steps: The method used in this comparative example is basically the same as that in Example 1, except that no desulfurized gypsum is added in step 3 and no desulfurized gypsum powder is added in step 4; the missing parts are filled with an equal amount of fly ash. The remaining steps are the same as in Example 1, and the resulting sample is denoted as D2.

[0039] Comparative Example 3 A method for preparing non-fired bricks includes the following steps: This comparative example is basically the same as Example 1, except that no composite activator is added in step 4, and only water is used for mixing. The remaining steps are the same as in Example 1, and the resulting sample is denoted as D3.

[0040] Comparative Example 4 This comparative example refers to the method of Example 1 in patent CN115286332A to prepare a steel slag-blast furnace slag non-fired brick as a comparison. The specific steps are as follows: (1) The steel slag is cooled for 28 hours, iron is selected, and sieved to obtain steel slag undersize with a particle size ≤1.5mm; (2) Blast furnace slag, water and steel slag undersize are mixed at a mass ratio of 2:1, and the moisture content is controlled at 33%. First, it is mixed at 15r / min for 8 minutes (water is added in batches), and then mixed at 25r / min for 4 minutes to obtain a slurry; (3) The slurry is vibrated and molded, and cured at 28℃ for 4.5 hours to obtain non-fired bricks. The obtained sample is recorded as D4.

[0041] Application examples The performance of the non-fired bricks S1-S4 and D1-D4 prepared in the above embodiments and comparative examples was tested. The test method was in accordance with GB / T2542-2012 "Test Methods for Masonry Bricks". The test results are shown in Table 3.

[0042] Table 3. Performance test results of the non-fired bricks in each embodiment and comparative example.

[0043] Note: Sample D4 had too low strength and was not tested for frost resistance.

[0044] The following conclusions can be drawn from the test results in Table 3: 1. Comprehensive advantages of the non-fired bricks of the present invention: The non-fired bricks prepared in Example 1 (S1) have a compressive strength of 24.8 MPa, a flexural strength of 5.2 MPa, a water absorption rate of 9.2%, and excellent frost resistance. All indicators far exceed the requirements of the national standard MU15. This fully demonstrates the advanced nature and synergistic effect of the technical route of this invention, which uses riverbed sediment as the core and combines it with multi-source industrial waste residue.

[0045] 2. Importance of Sediment Activation Treatment: Comparing S1 and S3, it can be seen that the 28-day strength of the sediment (S3) that was not activated by co-milling with shell powder decreased from 24.8 MPa to 19.3 MPa, while the water absorption rate and freeze-thaw loss rate increased. This indicates that co-milling with shell powder not only activated the sediment but also introduced an active calcium source, promoting the gelation reaction.

[0046] 3. Synergistic effect of red mud and desulfurized gypsum: Comparing S1 with D1 and D2, it can be seen that without the addition of red mud (D1) or desulfurized gypsum (D2), the 28-day strength of the unfired bricks decreased to 21.2 MPa and 20.5 MPa, respectively, showing a significant reduction. This indicates that the alkaline environment and active aluminum-iron provided by the red mud, as well as the sulfate provided by the desulfurized gypsum, reacted synergistically with other components in the system, generating more cementing products (such as AFt, hydrated calcium aluminate, etc.), thus improving the strength.

[0047] 4. The crucial role of the composite activator: Comparing S1 and D3, it can be seen that without the addition of the composite activator (D3), the strength drops significantly to 12.6 MPa, while the water absorption and freeze-thaw loss rates increase significantly. This indicates that the composite activator is crucial for fully activating the activity of siliceous aluminosilicate materials such as slag and sediment, and is key to obtaining high strength and high stability.

[0048] 5. Positive effects of pre-curing: Comparing S1 and S4, it can be seen that adding the pre-curing step (S4) slightly increases the strength and decreases the water absorption rate. This indicates that pre-curing helps to remove excess water, allowing for a more complete subsequent hydration reaction and a denser brick body.

[0049] 6. Comparison with existing technologies: Comparative Example 4 (D4) uses existing patented technology to prepare non-fired bricks with extremely low strength, which is in stark contrast to the S1-S4 samples of this invention.

[0050] In summary, this invention successfully provides a method for preparing high-performance, green, high-strength, non-fired bricks using riverbed sediment as the core, combined with various industrial wastes such as steel slag, red mud, desulfurized gypsum, blast furnace slag, and fly ash, through scientific proportioning and innovative activation and excitation processes. This method not only achieves large-scale, high-value utilization of riverbed sediment and various industrial wastes, but also produces high-quality building materials with performance far exceeding national standards, possessing extremely high economic, environmental, and social benefits, and has a very broad prospect for promotion and application.

[0051] The above description is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing non-fired bricks using riverbed sediment combined with multi-source industrial waste, characterized in that, Includes the following steps: Step 1: After dewatering and screening to remove impurities, the riverbed sediment with a moisture content of ≤60% is activated to obtain activated sediment. Step 2: The steel slag is cooled, selected for iron, screened and ground to obtain steel slag powder with a particle size ≤0.08mm; Step 3: Dry and grind the red mud, desulfurized gypsum, blast furnace slag and fly ash respectively to obtain red mud powder, desulfurized gypsum powder, blast furnace slag powder and fly ash with a particle size ≤0.08mm respectively. Step 4: By weight, take 100 parts of activated bottom mud obtained in Step 1, 10-30 parts of steel slag powder obtained in Step 2, 5-20 parts of red mud powder obtained in Step 3, 3-10 parts of desulfurized gypsum powder, 10-25 parts of blast furnace slag powder, 5-15 parts of fly ash, 2-10 parts of composite activator, and 10-25 parts of water, mix them evenly to obtain a mixture. Step 5: Place the mixture obtained in Step 4 into a mold, press it under a pressure of 15-25 MPa, hold the pressure for 10-30 seconds, and obtain a brick blank; Step 6: Cur the brick blanks obtained in Step 5 at a temperature of 20-30℃ and a humidity of ≥90% for 7-28 days to obtain non-fired bricks.

2. The preparation method according to claim 1, characterized in that, In step 1, the activation treatment is a mechanical-chemical coupling activation; the dewatered and screened riverbed sediment is mixed with the activator at a mass ratio of 1:(0.1-0.3), and ball-milled for 1-3 hours until the particle size of the mixture is ≤0.08mm; the activator is one or more of shell powder, quicklime or carbide slag.

3. The preparation method according to claim 1, characterized in that, In step 2, the cooling time of the steel slag is ≥24h, the total iron content of the steel slag after iron selection is 0.5-1.0 wt%, and the moisture content of the steel slag undersize is ≤0.2wt%.

4. The preparation method according to claim 1, characterized in that, In step 3, the red mud has a sodium oxide content of 2-5 wt%, an aluminum oxide content of 20-30 wt%, and an iron oxide content of 20-30 wt%; the desulfurized gypsum has a calcium sulfate dihydrate content of ≥85 wt%; the blast furnace slag has a titanium dioxide content of 13-15 wt%; and the fly ash is Grade I or Grade II fly ash.

5. The preparation method according to claim 1, characterized in that, In step 4, the composite activator is a mixture of an alkaline activator and a salt activator in a mass ratio of (2-4):1; the alkaline activator is one or more of water glass, sodium hydroxide, and potassium hydroxide; and the salt activator is one or more of sodium sulfate, sodium carbonate, and sodium aluminate.

6. The preparation method according to claim 1, characterized in that, In step 4, the mixing is carried out in a stepwise mixing manner: first, the activated bottom mud, steel slag powder, red mud powder, desulfurized gypsum powder, blast furnace slag powder and fly ash are dry mixed for 2-5 minutes, and then the composite activator and water are added for wet mixing for 5-10 minutes to ensure that the materials are mixed evenly.

7. The preparation method according to claim 1, characterized in that, In step 6, the maintenance is carried out in a standard maintenance room with daily water spraying for humidification; or pre-maintained for 12-48 hours in an environment with a temperature of 20-30℃ and a relative humidity of 40%-70%, and then standard maintenance is carried out.

8. The non-fired brick obtained by the preparation method according to any one of claims 1 to 7, characterized in that, The unfired bricks have a 28-day compressive strength ≥20MPa, a flexural strength ≥4.5MPa, a water absorption rate ≤12%, and a strength loss rate ≤15% after 25 freeze-thaw cycles.

9. The application of the non-fired bricks as described in claim 8 in walls, roads, slope protection and non-load-bearing walls of buildings.

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