Baking-free brick and production process thereof

Abstract

The invention belongs to the technical field of building materials, and provides a baking-free brick and a production process thereof, the baking-free brick comprises the following raw materials: 58-62% of industrial waste residue, 2.5-3.5% of stone nitrate, 8-10% of cement, 2.8-3.5% of quick lime, 0.15-0.25% of ash powder, 0.18-0.22% of JFS activator, and the balance of water; industrial solid waste resources are effectively utilized, energy consumption and production cost are reduced, exciting agent ions are promoted to diffuse to stone powder lattice defect sites through the steam heat effect, a nano water film enhances solid-liquid interface ion exchange, the material reaction activity index is remarkably increased, high-temperature sintering is not needed, and the requirement for green building material development is met; the environmental pollution is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, in particular to a non-fired brick and a production process thereof. Background Art

[0002] Currently, the production of traditional unfired bricks mainly relies on natural resources such as ordinary clay or coal slag or industrial solid waste as raw materials, and the finished products are obtained through high-temperature sintering;

[0003] However, natural clay resources are limited, restricting their development and utilization. Furthermore, the high-temperature sintering process consumes enormous amounts of energy, resulting in significant carbon emissions and making it difficult to meet the requirements of environmental protection and sustainable development. Furthermore, while using industrial solid wastes such as fly ash and slag as raw materials offers the advantages of reducing raw material costs and recycling resources, their relatively low reactivity and poorly controlled reactions can easily lead to unstable finished product strength and uneven dimensional shrinkage. Furthermore, achieving high-quality products is difficult without effective activation measures.

[0004] In addition, traditional processes generally rely on high-temperature sintering, which has high energy consumption, long production cycle and large equipment investment. It is not only expensive, but also limits its promotion and application in some regions and small and medium-sized enterprises.

[0005] To this end, technicians in this field have proposed a fire-free brick and its production process, aiming to effectively utilize industrial solid waste resources, reduce energy consumption and production costs, improve the stability of product performance, meet the requirements of green building materials development, and reduce environmental pollution. Summary of the Invention

[0006] In order to solve the above technical problems, the present invention provides a fire-free brick and a production process thereof to solve the problems raised in the background technology.

[0007] According to a first aspect of the present disclosure, a fired-free brick is proposed, which is composed of the following raw materials: 58-62% industrial waste slag, 2.5-3.5% saltpeter, 8-10% cement, 2.8-3.5% quicklime, 0.15-0.25% ash powder, 0.18-0.22% JFS activator, and the balance is water.

[0008] Preferably, the mixture is composed of the following raw materials: 60% industrial waste residue, 3% saltpeter, 10% cement, 3% quicklime, 0.2% ash powder, 0.2% JFS activator, and the balance is water.

[0009] Preferably, the industrial waste residue is stone powder with a particle size of ≤1mm; the saltpeter is recycled aggregate from construction waste with a gradation of 0.5-3mm continuous gradation; and the ash powder is dust collected from coal-fired power plants with a loss on ignition of ≤8%.

[0010] Preferably, the JFS activator is composed of the following components: sodium sulfate accounts for 35-45wt%, sodium metasilicate accounts for 25-35wt%, triethanolamine accounts for 8-12wt%, and the balance is calcium lignin sulfonate.

[0011] According to a second aspect of the present disclosure, a production process for unfired bricks is proposed, comprising the following steps:

[0012] S1. Dry mix the stone powder, ash powder and JFS activator, spray 20% of the total water volume, and activate in a closed reaction chamber for 12-24 hours;

[0013] S2, add saltpeter, cement and quicklime in proportion;

[0014] S3, using the staged water addition method: first add 50% of the total water and stir for 2 minutes, then add the remaining 30% of water and stir for 3 minutes, so that the final moisture content is controlled at 14±1%;

[0015] S4, sent to the molding machine via a heat preservation conveyor belt with a temperature of 40±5℃;

[0016] S5. Vibration pressing at 30±2MPa, vibration frequency 45-50Hz, holding pressure for 10s;

[0017] S6. Stack the materials in layers using an automatic palletizer, with breathable isolation pads placed between the layers.

[0018] S7. Set up a two-stage curing process; the first stage: steam curing at a temperature of 55±5℃ and a humidity of ≥90% for 36 hours; the second stage: curing in a natural curing shed covered with plastic film for 25-30 days;

[0019] S8. Finished products are shipped when their compressive strength is ≥18MPa and their moisture content is ≤6%.

[0020] Preferably, in step S1, 0.1-0.2 MPa low-pressure steam is introduced during the activation process to maintain the material temperature at 50-60°C.

[0021] Preferably, in step S3, a planetary mixer is used for stirring, with an orbital speed of 25 r / min and an autorotational speed of 45 r / min, and a total stirring time of 8-10 min.

[0022] Preferably, during the second stage of curing in step S7, spray humidification is performed for 5 minutes every 48 hours, and the CO2 concentration in the curing shed is controlled to be ≤500ppm.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The core raw materials of the present invention are stone powder, saltpeter and ash powder, all of which are industrial solid wastes, which greatly reduce the consumption of natural resources, meet the requirements of circular economy and green building materials development, and reduce solid waste stacking pollution and environmental burden.

[0025] 2. The present invention promotes the diffusion of activator ions to the defect sites of the stone powder lattice through the steam thermal effect, and the nano-water film enhances the ion exchange at the solid-liquid interface, significantly improving the reaction activity index of the material and increasing the XRD amorphous phase increment; and adopts segmented water addition and stirring to achieve uniform dispersion of the material, avoid segregation caused by excessive local water, and ensure that the rheological properties meet the molding density requirements.

[0026] 3. The solid waste raw materials used in the present invention have low cost, short production cycle, and no need for high-temperature sintering, which can effectively reduce energy consumption and thus reduce overall costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention is a flow chart of the production process of unburned bricks. DETAILED DESCRIPTION

[0028] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0029] Example 1: The present invention provides an unburned brick composed of the following raw materials: 60% stone powder, 3% saltpeter, 10% cement, 3% quicklime, 0.2% ash powder, 0.2% JFS activator, and the balance water.

[0030] The particle size of the stone powder is ≤1mm; the saltpeter is recycled aggregate from construction waste, with a gradation of 0.5-3mm continuous gradation; and the ash powder is dust collected from coal-fired power plants, with a loss on ignition of ≤8%.

[0031] The JFS activator is composed of the following components: sodium sulfate accounts for 35-45wt%, sodium metasilicate accounts for 25-35wt%, triethanolamine accounts for 8-12wt%, and the balance is calcium lignin sulfonate.

[0032] Stone powder is used as core aggregate and reaction matrix, mainly providing calcium silicate and calcium oxide components. Its micron-sized particles (≤1mm) are used to increase the specific surface area and promote ion exchange; its high CaO content dissociates into Ca in an alkaline environment. 2+ , and generate calcium silicate hydrate (CSH) gel with the activator to form the brick skeleton, making the solid waste utilization rate greater than 95%, reducing the consumption of natural resources;

[0033] Saltpeter is used as a physical filling skeleton to optimize the particle grading curve; its coarse particles form an "arch effect" support structure to improve compressive strength, while fine particles fill the gaps between the stone powder and reduce porosity;

[0034] Cement provides traditional Portland cement hydration products to supplement the CSH gel network, which is used to ensure early strength and solve the demoulding strength problem of unfired bricks;

[0035] Quicklime is used to release highly active Ca(OH)2, creating a strong alkaline environment, thereby stimulating the dissolution of aluminosilicates in the stone powder, increasing the reaction rate, and forming calcium aluminate hydrate (CAH) with Al2O3 in the ash powder, thereby enhancing durability;

[0036] Ash powder induces directional crystallization of CSH gel through nanoparticles, reduces drying shrinkage, and fills 10-100nm capillaries, reducing freeze-thaw mass loss rate;

[0037] JFS activator is a composite chemical activating system. Its sodium sulfate breaks the Si-O covalent bond of stone powder and increases the free [SiO4] 4- Its sodium metasilicate is used to provide active silicon source, so that the polymerization degree of CSH gel is from Q 2 Upgrade to Q 3 Its triethanolamine catalyzes the hydrolysis of quicklime, increasing Ca 2+ dissolution efficiency;

[0038] Water serves as a reaction medium and a carrier for adjusting rheological properties.

[0039] Example 2: As shown in the attached Figure 1 As shown, the present invention provides a production process for unburned bricks, comprising the following steps:

[0040] S1. After dry mixing stone powder, ash powder and JFS activator, 20% of the total water volume is sprayed by atomization and activated in a closed reaction chamber for 12-24 hours; during the activation process, 0.1-0.2MPa low-pressure steam is introduced to maintain the material temperature at 50-60°C; the activator ions diffuse to the defect sites of the stone powder lattice through the steam thermal effect, and the atomized water forms a nano-water film, which promotes ion exchange at the solid-liquid interface, thereby improving the reaction activity index and increasing the amorphous phase increment shown by XRD.

[0041] S2. Add saltpeter, cement and quicklime in the proportions in Example 1.

[0042] S3. Use a staged water addition method: first add 50% of the total water and stir for 2 minutes to wet the agglomerates and destroy the van der Waals forces between the particles, then add the remaining 30% of water and stir for 3 minutes to hydraulically shear and disperse the gelled encapsulated mass, so that the final moisture content is controlled at 14±1%, thereby adjusting the rheology to meet the molding requirements; stir using a planetary mixer with an orbital speed of 25 r / min and a rotation speed of 45 r / min, and a total stirring time of 8-10 minutes.

[0043] S4. The material is sent to the molding machine via an insulated conveyor belt with a temperature of 40±5℃; thereby maintaining the material temperature above the dew point temperature to prevent water from being separated out, making the moisture content fluctuation range ±0.3%, and ensuring the consistency of molding density.

[0044] S5. Vibration pressing at a pressure of 30±2MPa, a vibration frequency of 45-50Hz, and maintaining pressure for 10s; the high-frequency vibration causes the particles to undergo "liquefaction and rearrangement" to expel closed bubbles, and the high pressure promotes the conversion of the van der Waals force between the particles into chemical bonds, thereby reducing the porosity of the brick and improving the compressive strength.

[0045] S6. The bricks are stacked in layers by automatic palletizers, and breathable isolation pads are set between layers; this effectively avoids damage to the bricks caused by manual operation and improves production efficiency.

[0046] S7, set up a two-stage curing process; the first stage: temperature 55 ± 5 ℃, humidity ≥ 90% steam curing for 36 hours; through the high temperature and high humidity of steam curing to accelerate Ca 2+ +[SiO4] 4- →The polycondensation reaction of CSH effectively shortens the curing cycle;

[0047] The second stage: Cover with plastic film in the natural curing shed for 25-30 days, and spray humidification for 5 minutes every 48 hours. The CO2 concentration in the curing shed is controlled at ≤500ppm; by physically blocking the penetration of CO2, CSH is prevented from carbonizing and decomposing into CaCO3+SiO2 gel, and periodic humidification is performed to maintain the internal relative humidity and promote continuous hydration, thereby effectively controlling the carbonization depth and increasing the service life.

[0048] S8. Finished products are shipped when their compressive strength is ≥18MPa and their moisture content is ≤6%.

[0049] Experimental example:

[0050] 1. Compressive strength test

[0051] According to GB / T 2542-2012 “Test methods for masonry bricks”, three standard specimens (100 mm × 100 mm × 100 mm) were taken and pressure was applied on a press at a loading rate of 0.15 MPa / s, and the failure load was recorded.

[0052] 2. Flexural strength test

[0053] The three-point bending method was used, the specimen size was the same as the compressive strength test, the support spacing was 80 mm, the loading rate was 0.05 MPa / s, and the average value of three specimens was taken.

[0054] 3. Freeze resistance test

[0055] According to GB / T 4111-2013 "Test methods for concrete blocks and bricks", the specimens were subjected to 25 freeze-thaw cycles (freezing at -15°C for 4 hours and thawing at 5°C for 4 hours) to test the mass loss rate and strength loss rate.

[0056] 4. Water absorption and moisture content test

[0057] Water absorption rate: After the specimen is dried to constant weight, it is immersed in water for 48 hours and the percentage of water absorption to dry weight is calculated.

[0058] Moisture content: Take the actual moisture content of the finished bricks.

[0059] 5. Density and porosity test

[0060] Density: Measure the volume and mass of the specimen and calculate the apparent density.

[0061] Porosity: The density and theoretical density (take 2.4g / cm 3 ) to calculate the porosity.

[0062] 6. Carbonization coefficient test

[0063] The specimens were placed in an environment with a CO2 concentration of (20±3)%, a humidity of (70±5)% and a temperature of (20±5)°C for 28 days, and the ratio of the compressive strength after carbonization to the original strength was tested.

[0064] The experimental results are shown in the following table:

[0065]

[0066] Results analysis: In terms of mechanical properties, the compressive strength reaches 20.5MPa, exceeding the standard requirement by 13.9%, and the flexural strength is 3.8MPa, indicating that the brick structure is dense and has excellent bearing capacity. In terms of durability, the mass loss and strength loss in the frost resistance test are far below the standard limit, and the water absorption rate is 9.5%, which is lower than that of traditional clay bricks (15-20%), indicating that the brick has strong impermeability and freeze-thaw resistance. In terms of environmental protection and energy saving, the apparent density is 2080kg / m 3 Close to ordinary concrete bricks, the porosity of 14.2% optimizes the thermal insulation performance; the carbonization coefficient of 0.85 meets the requirements of green building materials, and the solid waste utilization rate reaches more than 95%, which is in line with the goals of the circular economy.

[0067] Comparative Example:

[0068] Comparison objects: traditional clay bricks, using commercially available common fired clay bricks; the unfired bricks of the present invention;

[0069] Testing items and methods: Adopt the testing scheme in the experimental example and add the comparison of production energy consumption and solid waste utilization rate;

[0070] The comparison of performance parameters after testing is shown in the following table:

[0071]

[0072]

[0073]

[0074] Conclusion Analysis: In terms of mechanical properties, the compressive strength of the unfired bricks of this invention reaches MU20 (far exceeding the MU10 of traditional clay bricks), and the flexural strength and frost resistance indicators are better than the requirements of superior products in GB / T 2542-2012, making it suitable for high-strength scenarios such as load-bearing walls. In terms of environmental performance, the solid waste utilization rate reaches over 95%. Every 10,000 tons of unfired bricks produced can absorb approximately 5,800 tons of industrial waste slag, reducing the solid waste storage area by approximately 2,000 m 2； The production process does not involve high-temperature sintering, and the unit energy consumption is only 27% of that of traditional clay bricks, reducing carbon emissions by about 60%. In terms of durability and practicality, the low water absorption rate (9.5%) and high carbonization coefficient (0.85) make it more stable in humid environments and during long-term use. The strength loss rate after freeze-thaw cycles is only 40% of that of traditional bricks, and the service life can be extended by 1.5-2 times. In terms of cost, the raw material cost of the present invention is 30% lower than that of traditional clay bricks, and the production cycle is shortened to 30-35 days (traditional bricks require 50-60 days). No large-scale sintering kilns are required, and equipment investment is reduced by 40%, making it suitable for promotion by small and medium-sized enterprises.

[0075] The unfired bricks of the present invention surpass traditional clay bricks in terms of mechanical properties, durability, environmental protection and energy saving through efficient utilization of industrial solid waste, composite stimulant activation technology and segmented maintenance process. In particular, they have significant advantages in the fields of solid waste resource utilization and low-carbon production, providing a feasible solution for the upgrading of green building materials.

[0076] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment (i.e., those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0077] It will be understood that in the development of any actual embodiment, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but for those of ordinary skill having the benefit of this disclosure, the development effort will be a routine task of design, fabrication, and production without undue experimentation.

[0078] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A fired brick, characterized in that: It is composed of the following raw materials: industrial waste residue 58-62%, saltpeter 2.5-3.5%, cement 8-10%, quicklime 2.8-3.5%, ash powder 0.15-0.25%, JFS activator 0.18-0.22%, and the balance is water.

2. The unburned brick according to claim 1, characterized in that: It is composed of the following raw materials: industrial waste slag 60%, saltpeter 3%, cement 10%, quicklime 3%, ash powder 0.2%, JFS activator 0.2%, and the balance is water.

3. The unburned brick according to claim 2, characterized in that: The industrial waste residue is stone powder with a particle size of ≤1mm; the saltpeter is recycled aggregate from construction waste with a gradation of 0.5-3mm continuous gradation; and the ash powder is dust collected from coal-fired power plants with a loss on ignition of ≤8%.

4. The unburned brick according to claim 2, characterized in that: The JFS activator is composed of the following components: sodium sulfate accounts for 35-45wt%, sodium metasilicate accounts for 25-35wt%, triethanolamine accounts for 8-12wt%, and the balance is calcium lignin sulfonate.

5. A production process for unburned bricks, applied to the unburned bricks according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Dry mix the stone powder, ash powder and JFS activator, spray 20% of the total water volume, and activate in a closed reaction chamber for 12-24 hours; S2, add saltpeter, cement and quicklime in proportion; S3, using the staged water addition method: first add 50% of the total water and stir for 2 minutes, then add the remaining 30% of water and stir for 3 minutes, so that the final moisture content is controlled at 14±1%; S4, sent to the molding machine via a heat preservation conveyor belt with a temperature of 40±5℃; S5. Vibration pressing at 30±2MPa, vibration frequency 45-50Hz, holding pressure for 10s; S6. Stack the materials in layers using an automatic palletizer, with breathable isolation pads placed between the layers. S7. Set up a two-stage curing process; the first stage: steam curing at a temperature of 55±5℃ and a humidity of ≥90% for 36 hours; the second stage: curing in a natural curing shed covered with plastic film for 25-30 days; S8. Finished products are shipped when their compressive strength is ≥18MPa and their moisture content is ≤6%.

6. A process for producing unburned bricks according to claim 5, characterized in that: In step S1, 0.1-0.2 MPa low-pressure steam is introduced during the activation process to maintain the material temperature at 50-60°C.

7. The process for producing unburned bricks according to claim 5, wherein: In step S3, a planetary mixer is used for stirring, with an orbital speed of 25 r / min and an autorotational speed of 45 r / min, and a total stirring time of 8-10 min.

8. The process for producing unburned bricks according to claim 5, wherein: During the second stage of curing in step S7, spray humidification is performed for 5 minutes every 48 hours, and the CO2 concentration in the curing shed is controlled to be ≤500ppm.

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