Dicalcium silicate and fly ash-based high-strength earthenware brick as well as preparation method and application thereof

Abstract

The invention provides a dicalcium silicate and fly ash based high-strength earthenware brick and a preparation method and application thereof.The method comprises the steps that firstly, dried dicalcium silicate, fly ash powder and water are evenly mixed, and a mixture is obtained; secondly, the mixture is subjected to forming treatment, and a blank is formed; and finally, air-drying the green body, and curing by using CO2 to obtain the dicalcium silicate and fly ash-based high-strength earthenware brick. According to the invention, two bulk wastes, namely CO2 and fly ash, are taken as key substances, so that the CO2 and the fly ash are efficiently utilized, the environmental pressure is reduced, the product strength is higher than that of a CO2-cured pure dicalcium silicate earthenware brick, the reaction rate is higher, and the production efficiency can be improved. In production, waste materials are used frequently, the cost of raw materials is greatly reduced, only mixing, forming, air drying and CO2 curing are needed in the process, complex equipment is not needed, and the production threshold is reduced. Meanwhile, according to the method, no pollutant is discharged, CO2 is consumed, a traditional high-temperature firing link is abandoned, energy consumption is reduced fundamentally, and environment-friendly and energy-saving production is achieved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of fly ash treatment and sinter-free ceramic brick, and particularly relates to a dicalcium silicate and fly ash-based high-strength ceramic brick and a preparation method and application thereof. BACKGROUND

[0002] Ceramics is an important building material, has the characteristics of high strength, corrosion resistance, frost resistance and earthquake resistance due to its small density and high mechanical properties. With good plasticity and formability, ceramic materials can be widely used in building walls, floor paving and other fields. However, the main production raw material of ceramics, clay and shale, belongs to non-renewable resources, which has been prohibited or restricted from mining, and the sintering of ceramics requires high temperature above 1100 DEG C, which has high energy consumption and easily emits a large amount of greenhouse gases.

[0003] The use of solid waste to prepare ceramics can not only realize resource utilization but also reduce the dependence on non-renewable resources. At present, the ceramics prepared from solid waste have the problems of poor overall strength, high processing cost and large production energy consumption.

[0004] Therefore, a scheme for preparing ceramics from solid waste is needed to improve the overall strength of ceramics and reduce the production energy consumption. SUMMARY

[0005] Therefore, the application provides a dicalcium silicate and fly ash-based high-strength ceramic brick and a preparation method and application thereof, which are used to solve the problem of how to prepare high-strength ceramics from solid waste and gas waste.

[0006] To achieve the above technical purposes, the application adopts the following technical scheme: In a first aspect, the application provides a preparation method of a dicalcium silicate and fly ash-based high-strength ceramic brick, which comprises the following steps: S10, the dried dicalcium silicate and fly ash powder are fully mixed and uniformly added with water, and then stirred uniformly to obtain a mixture; S20, the mixture is subjected to forming treatment to form a green body; S30, the green body is dried and cured by using CO2 to obtain the dicalcium silicate and fly ash-based high-strength ceramic brick.

[0007] Preferably, the dicalcium silicate and fly ash-based high-strength ceramic brick is prepared from the following raw materials in mass parts: dicalcium silicate 10-90 parts, fly ash 10-90 parts and water 5 parts.

[0008] Preferably, in the step S10, the mass ratio of the dicalcium silicate to the fly ash is 10: (1-90).

[0009] Preferably, the dicalcium silicate comprises components with mass percentages as follows: Ca2SiO4 85%~90%, CaO 5%~10%, MgO 2%~3%, Al2O3 1%~2%, Fe2O3 >0% and ≤0.10%; the particle size D50 of the dicalcium silicate is 14.1 μm.

[0010] Preferably, the fly ash comprises components with mass percentages as follows: SiO2 43.01%, Al2O3 24.21%, Fe2O3 2.51%, CaO 5.61%; the particle size D50 of the fly ash is 26.3 μm.

[0011] Preferably, in the step S20, the forming method is casting forming, and the size of the green body is 20×20×20 mm.

[0012] Preferably, in the step S30, the curing temperature is 20~60 ℃, and the curing partial pressure is 1~4 kPa.

[0013] Preferably, in the step S30, the curing temperature is 50 ℃, and the curing partial pressure is 4 kPa.

[0014] In a second aspect, the application provides a dicalcium silicate and fly ash based high-strength ceramic brick prepared by the method for preparing a dicalcium silicate and fly ash based high-strength ceramic brick according to any one of the above.

[0015] In a third aspect, the application provides use of the dicalcium silicate and fly ash based high-strength ceramic brick in the field of construction.

[0016] The beneficial effects of the present application are as follows: the present application provides a di-calcium silicate and fly ash based high-strength ceramic brick and a preparation method and application thereof, the preparation method comprises the following steps: firstly, di-calcium silicate and fly ash powder after drying are fully mixed and uniformly mixed, then water is added, and stirring is uniformly carried out to obtain a mixture; secondly, the mixture is subjected to forming treatment to form a green body; finally, the green body is air-dried, and CO2 is used for curing and solidification, and the di-calcium silicate and fly ash based high-strength ceramic brick is obtained; the present application takes CO2 and fly ash, two kinds of large-batch industrial wastes with large quantity and wide range, as key participating substances, and prepares high-strength ceramic bricks by means of CO2 curing di-calcium silicate and fly ash, so that the efficient comprehensive utilization of the two kinds of wastes is realized, the wastes that need to be treated are converted into valuable production raw materials, and the environmental pressure caused by waste stacking or disposal is reduced; at the same time, compared with the ceramic bricks prepared by means of CO2 curing pure di-calcium silicate, the di-calcium silicate and fly ash based high-strength ceramic bricks prepared by the method have obvious improvement in core performance, have higher mechanical strength, can better meet the demand of actual application for the strength of ceramic bricks, have a significantly accelerated reaction rate, can effectively shorten the production cycle of ceramic bricks, and improve the production efficiency; in addition, from the production level, a large amount of wastes are used in the raw materials, the raw material procurement cost is greatly reduced, and the preparation process flow is simple, only needs to go through the steps of uniform mixing of raw materials, forming of the mixture, air-drying of the green body, and CO2 curing and solidification, does not need complex equipment or operation, and reduces the production threshold; finally, the method also has outstanding environmental protection and energy saving advantages, on the one hand, the whole production process is free of pollutant emission, and actively consumes CO2, which conforms to the production concept of environmental friendliness, and on the other hand, it abandons the high-temperature firing link in the traditional ceramic brick production process, and the traditional high-temperature firing is the key to cause the high energy consumption of ceramic brick production, so the method can fundamentally and effectively reduce the high energy consumption problem of traditional ceramic brick production, and realizes energy-saving production. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0018] In view of the deficiencies of the prior art, the present application aims to overcome the technical shortcomings of CO2 and fly ash, two kinds of large-batch wastes, in utilization, and proposes a method for preparing high-strength ceramic bricks by means of CO2 curing di-calcium silicate and fly ash, so as to solve the technical problems of high CO2 and fly ash treatment cost and low economic value in the prior art. At the same time, on the basis of realizing the collaborative treatment of CO2 and fly ash, two kinds of large-batch gas waste and solid waste in power plant flue gas, the method can also significantly improve the compressive strength of ceramic bricks, and ultimately achieve the purpose of preparing low-cost and high-value ceramic products.

[0019] The inventors found that the CO2 curing technology can not only promote the rapid hardening of calcium-containing minerals, but also can utilize the CO2 in industrial waste gas as a resource. Especially, the industrial waste gas rich in CO2 such as power plant flue gas and steel smelting tail gas can be directly applied to the preparation of ceramic bricks to realize the combination of waste gas emission reduction and resource utilization.

[0020] The main component of dicalcium silicate is Ca2SiO4, and it also contains a certain amount of CaO, MgO, Al2O3 and Fe2O3 and other metal oxides. Among them, Ca2SiO4 not only has excellent cementing performance and can generate C-S-H gel in the hydration process, but also can react with CO2 to generate CaCO3, thereby realizing the curing effect. In addition, Ca2SiO4 can be prepared by lime and quartz, and the preparation process is simple and the production cost is low, which has the feasibility of resource preparation of ceramic bricks.

[0021] Fly ash is mainly composed of SiO2 and Al2O3, and also contains Fe2O3, CaO and MgO and other alkaline metal oxides. In the prior art, fly ash is often used as a raw material for ceramic bricks / particles, but it usually needs to be sintered at high temperature, and the sintering temperature is generally above 1100℃, which leads to high energy consumption and large carbon emissions, which is not conducive to green and low-carbon development. In addition, the high content of Al2O3 in fly ash has low reactivity in the conventional sintering system and is difficult to be fully utilized. In the preparation process of the dicalcium silicate and fly ash-based high-strength ceramic brick described in the present application, the free CaO in fly ash and dicalcium silicate reacts with H2O to generate Ca(OH)2, which increases the alkalinity of the system, thereby promoting the dissolution and reactivity of Si and Al components in fly ash; under the alkaline environment, Al2O3 which is difficult to utilize under conventional sintering conditions can react with Ca 2+ , SiO4 4- to generate C-A-S-H gel through polycondensation, effectively accelerating the curing rate and early strength of the material; at the same time, the generated Ca(OH)2 is easy to react with CO2 to generate CaCO3, further accelerating the curing process and improving the structural density; Fe2O3 can fill the skeleton pores, improve the particle size distribution, and improve the material density, thereby significantly enhancing the compressive strength of the ceramic brick. In addition, fly ash is a solid waste that is difficult to dispose of, and if it is used as a raw material for the preparation of CO2 curing ceramic bricks, it not only realizes the resource utilization, but also replaces part of the non-renewable resources, thereby effectively reducing the dependence on traditional resources.

[0022] Therefore, the present application adopts the CO2 curing dicalcium silicate-fly ash process to prepare ceramic bricks, which not only can avoid the high energy consumption and high emission problems caused by traditional high-temperature sintering, but also can significantly improve the activity of difficult-to-utilize components such as Al2O3 in fly ash, further improving the curing rate and mechanical properties of ceramic bricks.

[0023] The application first provides a preparation method of a dicalcium silicate and fly ash based high-strength ceramic brick, comprising the following steps: S10, the dried dicalcium silicate and fly ash powder are fully mixed and uniformly added with water, and then stirred uniformly to obtain a mixture.

[0024] S20, the mixture is subjected to a forming treatment to form a green body; S30, the green body is placed in a natural environment for air drying for 3 hours, and then placed in a curing box for curing and solidification by using CO2, so that the dicalcium silicate and fly ash based high-strength ceramic brick is obtained.

[0025] In the embodiment of the application, the method is used for preparing the dicalcium silicate and fly ash based high-strength ceramic brick by mixing the dried dicalcium silicate, fly ash powder and water uniformly, forming, air drying the green body and curing and solidifying by using CO2, so that the resource utilization of CO2 in the boiler tail gas and fly ash, two types of waste, can be realized, and the waste is turned into treasure; meanwhile, the high-strength ceramic brick product can be prepared, the process does not need the high-temperature sintering link of traditional ceramic production, the energy consumption and carbon emission are effectively reduced, the advantages of low cost and environmental friendliness are combined, and the development of ceramic preparation towards the green and low-carbon direction is promoted.

[0026] In the embodiment of the application, the dicalcium silicate and fly ash based high-strength ceramic brick is prepared from the following raw materials in mass parts: dicalcium silicate 10-90 parts, fly ash 10-90 parts, and water 5 parts, and meanwhile, a certain amount of CO2 is introduced for subsequent curing; preferably, the dicalcium silicate is 80 parts, and the fly ash is 20 parts; more preferably, the dicalcium silicate is 70 parts, and the fly ash is 30 parts.

[0027] Specifically, the raw material ratio of the dicalcium silicate and fly ash based high-strength ceramic brick is flexible and the preferred scheme is reasonable, the industrial waste fly ash can be used in a large amount, the resource recovery is realized, and the raw material cost is reduced; the fixed water consumption is beneficial to controlling the process stability, and the high-strength ceramic brick product can be prepared by cooperating with the related preparation process, and the economic value and environmental benefits are combined.

[0028] In the S10 step, the mass ratio of the dicalcium silicate to the fly ash is 10: (1-90); within the mass ratio range, the dicalcium silicate and fly ash based high-strength ceramic brick obtained has higher compressive strength. Preferably, it is 10: (2-5), more preferably, it is 10: (2-4), and most preferably, it is 10: (2.95-3.05).

[0029] In the S10 step, the dicalcium silicate comprises the following components in mass percentage: Ca2SiO4 85%-90%, CaO 5%-10%, MgO 2%-3%, Al2O3 1%-2%, and Fe2O3 >0% and ≤0.10%, and the water content of the dicalcium silicate after drying is 1%; the particle size D50 of the dicalcium silicate is 14.1 μm.

[0030] In the S10 step, the fly ash is the main solid waste discharged by the coal-fired power plant, and the main components are SiO2, Al2O3 and CaO. Among them, the particle size D50 of the fly ash is 26.3 μm, and the main chemical component mass percentage is: SiO243.01%, Al2O324.21%, Fe2O32.51% and CaO 5.61%, and the water content after drying is 1%.

[0031] In the S20 step, the forming method is the casting method, and the size of the green body is 20*20*20 mm, and no external forming pressure is needed.

[0032] In the S30 step, during the curing process, the curing temperature is 20~60℃, preferably 40~60℃, more preferably 50℃, and the curing partial pressure is 1~4kPa, preferably 4kPa. First, the chemical components Ca2SiO4 and CO2 in the dicalcium silicate can generate a dense calcite CaCO3 skeleton under the conditions of 50℃ and 4kPa gas partial pressure, while inhibiting the generation of the CaCO3 structure of vaterite and aragonite, which is beneficial to improve the macroscopic compressive strength of the ceramic brick.

[0033] The application uses CO2 and fly ash as raw materials to prepare ceramic bricks. In the CO2 curing process, Al2O3 in the fly ash can be dissolved and reacted with Ca 2+ , SiO4 4- to generate C-A-S-H gel through polycondensation, thereby accelerating the curing rate and improving the strength and density of the sample. Fe2O3 can fully fill the gaps of the CaCO3 skeleton and optimize the particle size distribution, further improving the density of the ceramic brick. SiO2 in the fly ash can react with CO2 and H2O to generate H4SiO4, and form silica gel through polymerization. The silica gel can fill and bond each microstructure through capillary action, adsorb harmful substances and heavy metal ions in the mixture, and play a good curing effect. In addition, by controlling the curing temperature, micro pores can be formed in the ceramic brick, so that the prepared ceramic brick has good expansion performance and excellent pore structure. At the same time, H2CO3 generated by the reaction of H2O and CO2 can enter the inside of the green body through the micropores, and react with Ca 2+ to generate CaCO3, forming a compact structure and a complete surface of the calcium carbonate basic skeleton, significantly improving the macroscopic strength of the ceramic brick.

[0034] Under the prior art, the preparation of ceramic bricks often needs to add binders and external additives, and is sintered in multiple stages at a high temperature. The application creatively proposes to cast on the basis of dry or semi-dry green body, and use CO2 to cure the green body. This process enhances the friction and contact force between particles, improves the mechanical interlocking effect, and forms a dense CaCO3 skeleton. The green body after forming has high density, the adhesion of the mixture is strong, and the compressive strength of the final product is also improved.

[0035] The application further provides the dicalcium silicate and fly ash based high-strength ceramic brick prepared by the preparation method.

[0036] The application further provides application of the dicalcium silicate and fly ash based high-strength ceramic brick in the field of building.

[0037] The application is further described below through specific examples.

[0038] Raw materials used in the examples and comparative examples are described below. The particle size D50 of the fly ash is 26.3 μm, and the mass percentage of the main chemical components is: SiO243.01%, Al2O324.21%, Fe2O32.51% and CaO 5.61%, and the water content after drying is 1%.

[0039] The dicalcium silicate comprises the following components in mass percentage: Ca2SiO488.25%, CaO 6.36%, MgO 2.12%, Al2O31.05%, Fe2O30.05%, and the water content of the dicalcium silicate after drying is 1%; the particle size D50 of the dicalcium silicate is 14.1 μm.

[0040] Example 1 Example 1 provides a preparation method of the dicalcium silicate and fly ash based high-strength ceramic brick, comprising the following steps: Step one: the fly ash is placed in an oven and dried for 4 h, and the fly ash with a water content of 1% is obtained after cooling to room temperature.

[0041] Step two: the fly ash 30 parts and the dicalcium silicate 70 parts are fully mixed, water is added and stirred for 10 min to obtain a mixture.

[0042] Step three: the mixture is injected into a mold to form a cube with a size of 20x20x20 mm.

[0043] Step four: the cube is placed in a curing tank and cured at 50℃, the curing pressure is 4 kPa, and the curing time is 28 d.

[0044] The ceramic brick obtained by curing for 28 d by the method of this example 1 has a compressive strength value of 114.2 MPa.

[0045] Example 2 Example 2 provides a method for preparing a high-strength ceramic brick based on dicalcium silicate and fly ash, comprising the following steps: Step one: Place the fly ash in an oven and dry for 4 hours. After cooling to room temperature, obtain fly ash with a water content of 1%.

[0046] Step two: Mix 20 parts of fly ash and 80 parts of dicalcium silicate. After adding water, stir for 10 minutes to obtain a mixture.

[0047] Step three: Pour the mixture into a mold to form a cube with a size of 20x20x20 mm.

[0048] Step four: Place the cube in a curing tank and cure in a 50°C curing oven at a curing pressure of 4 kPa for 28 days.

[0049] The compressive strength value of the ceramic brick obtained by curing for 28 days using the method of Example 2 is 75.4 MPa.

[0050] Example 3: Example 3 provides a method for preparing a high-strength ceramic brick based on dicalcium silicate and fly ash, comprising the following steps: Step one: Place the fly ash in an oven and dry for 4 hours. After cooling to room temperature, obtain fly ash with a water content of 1%.

[0051] Step two: Mix 40 parts of fly ash and 60 parts of dicalcium silicate. After adding water, stir for 10 minutes to obtain a mixture.

[0052] Step three: Pour the mixture into a mold to form a cube with a size of 20x20x20 mm.

[0053] Step four: Place the cube in a curing tank and cure in a 50°C curing oven at a curing pressure of 4 kPa for 28 days.

[0054] The compressive strength value of the ceramic brick obtained by curing for 28 days using the method of Example 3 is 75.6 MPa.

[0055] Comparative Example 1: Comparative Example 1 provides a method for preparing a high-strength ceramic brick based on dicalcium silicate, which is substantially the same as the preparation method provided in Example 1, except that: Step two: Mix 100 parts of dicalcium silicate with water and stir for 10 minutes to obtain a mixture.

[0056] The compressive strength value of the ceramic brick obtained by curing for 28 days using the method of Comparative Example 1 is 79.4 MPa, which is about 34.8 MPa lower than that of Example 1. The reason is that Al2O3 in fly ash dissolves and can react with Ca 2+ , SiO4 4-The calcium alumino-silicate hydrate is formed by polycondensation, thereby accelerating the solidification rate and improving the strength and density of the sample. Fe2O3 can fully fill the gaps of the CaCO3 skeleton, optimize the particle size distribution, and improve the density of the ceramic brick. Meanwhile, SiO2 in the fly ash can react with CO2 and H2O to form H4SiO4, and the H4SiO4 can polymerize to form silica gel. The silica gel can fill and bond the microstructure through capillary action, form a dense skeleton structure, and enhance the overall compressive strength of the ceramic brick.

[0057] Comparative Example 2: Comparative Example 2 provides a preparation method of a fly ash-based high-strength ceramic brick, which has substantially the same preparation method as that provided in Example 1, except that: Step two: 100 parts of fly ash were stirred with water for 10 minutes to obtain a mixture.

[0058] The compressive strength of the ceramic brick obtained by the method of Comparative Example 2 after 28 days of curing was 20.2 MPa, which was about 94 MPa lower than that of Example 1. The reason is that Ca2SiO4 in dicalcium silicate can react with CO2 to form a CaCO3 basic skeleton, and the formed CaCO3 basic skeleton has good compressive capacity, which can provide the overall compressive strength of the ceramic brick. It is further proved that relying on the bonding effect of silica gel and the filling effect of Fe2O3 can provide part of the strength, but the overall strength is much lower than that provided by the CaCO3 basic skeleton.

[0059] Comparative Example 3: Comparative Example 3 provides a preparation method of a dicalcium silicate and fly ash-based high-strength ceramic brick, which has substantially the same preparation method as that provided in Example 1, except that: Step four: the cube was placed in a curing tank and cured at 20℃, with a curing pressure of 4kPa and a curing time of 28d.

[0060] The compressive strength of the ceramic brick obtained by the method of Comparative Example 3 after 28 days of curing was 20.1 MPa, which was about 94.1 MPa lower than that of Example 1. The reason is that at 20℃, Ca2SiO4 in dicalcium silicate can react with CO2 to form CaCO3, but the formed CaCO3 is basically in the structure of vaterite. The vaterite structure of CaCO3 is stacked but does not form a relatively dense skeleton, and is bonded by the action of silica gel, so the overall compressive strength of the ceramic brick is poor.

[0061] Comparative Example 4: Comparative Example 4 provides a preparation method of a dicalcium silicate and fly ash-based high-strength ceramic brick, which has substantially the same preparation method as that provided in Example 1, except that: Step four: the cube was placed in a curing tank and cured at 40℃, with a curing pressure of 4kPa and a curing time of 28d.

[0062] The compressive strength of the ceramic brick obtained by curing for 28 days in the method of Comparative Example 4 was 31.1 MPa, which was decreased by about 83.1 MPa compared with Example 1. The reason was that at 40℃, Ca2SiO4 in dicalcium silicate could react with CO2 to form CaCO3, but the formed CaCO3 had a mixed structure of vaterite and calcite, the skeleton of CaCO3 with calcite structure was relatively broken, and the vaterite structure was embedded therein, the skeleton was incomplete, and the overall compressive strength of the ceramic brick was increased compared with Comparative Example 3 but still insufficient compared with Example 1 under the synergistic effect of CaCO3 and silica gel.

[0063] Comparative Example 5: Comparative Example 5 provides a preparation method of dicalcium silicate and fly ash-based high-strength ceramic brick, which is substantially the same as the preparation method provided in Example 1, and the only difference is that: Step four: put the cube into the curing tank, cure at 60℃, curing pressure is 4kPa, and curing time is 28d.

[0064] The compressive strength of the ceramic brick obtained by curing for 28 days in the method of Comparative Example 5 was 95.1 MPa, which was decreased by about 19.1 MPa compared with Example 1. The reason was that at 60℃, Ca2SiO4 in dicalcium silicate could react with CO2 to form CaCO3, but the formed CaCO3 had a mixed structure of aragonite, the skeleton of CaCO3 with calcite structure was relatively complete but still not dense, and the aragonite structure of CaCO3 was columnar or fibrous, so that the overall compressive strength of the ceramic brick was deviated.

[0065] Comparative Example 6: Comparative Example 6 provides a preparation method of dicalcium silicate and fly ash-based high-strength ceramic brick, which is substantially the same as the preparation method provided in Example 1, and the only difference is that: Step four: put the cube into the curing tank, cure at 50℃, curing pressure is 1kPa, and curing time is 28d.

[0066] The compressive strength of the ceramic brick obtained by curing for 28 days in the method of Comparative Example 6 was 34.4 MPa, which was decreased by about 79.8 MPa compared with Example 1. The reason was that at 1kPa, Ca2SiO4 in dicalcium silicate could react with CO2 to form CaCO3, but due to the low CO2 gas pressure, the penetration rate of CO2 into the ceramic brick body was low, the solidification rate of the ceramic brick was low, and the formed CaCO3 had a mixed structure of calcite and vaterite, the skeleton of CaCO3 was complete but not dense, and the vaterite structure was embedded therein, so that the overall compressive strength of the ceramic brick was poor.

[0067] Comparative Example 7: Comparative Example 7 provides a preparation method of a dicalcium silicate and fly ash based high-strength ceramic brick, which is substantially the same as the preparation method provided in Example 1, except that: Step four: place the cube into a curing tank, and cure at 50℃, with a curing pressure of 3kPa, and a curing time of 28d.

[0068] The compressive strength of the ceramic brick obtained in the method of Comparative Example 7 is 70.3MPa after 28d of curing, which is about 43.9MPa lower than that of Example 1. The reason is that at 3kPa, Ca2SiO4 in dicalcium silicate can react with CO2 to form CaCO3, but due to the slightly lower CO2 gas pressure, the penetration rate of the ceramic brick body is slightly lower, the solidification rate of the ceramic brick is slightly lower, and the overall compressive strength of the ceramic brick is slightly lower.

[0069] Comparative Example 8: Comparative Example 8 provides a preparation method of a dicalcium silicate and fly ash based high-strength ceramic brick, which is substantially the same as the preparation method provided in Example 1, except that: Step four: place the cube into a curing tank, and cure at 50℃, with a curing pressure of 4kPa, and a curing time of 1d.

[0070] The compressive strength of the ceramic brick obtained in the method of Comparative Example 8 is 24.4MPa after 1d of curing, which is about 89.8MPa lower than that of Example 1. The reason is that at 1d, Ca2SiO4 in dicalcium silicate can react with CO2 to form CaCO3, but the formed CaCO3 is a mixed structure of calcite and aragonite, the crystal size of the formed calcite is small and the proportion is small, and due to the short curing time, the ceramic brick is almost not solidified, and the complete CaCO3 skeleton is not formed, so the overall compressive strength of the ceramic brick is poor.

[0071] Comparative Example 9: Comparative Example 9 provides a preparation method of a dicalcium silicate and fly ash based high-strength ceramic brick, which is substantially the same as the preparation method provided in Example 1, except that: Step four: place the cube into a curing tank, and cure at 50℃, with a curing pressure of 4kPa, and a curing time of 14d.

[0072] The compressive strength of the ceramic brick obtained by curing for 14d in the method of Comparative Example 9 is 64.2 MPa, which is about 50 MPa lower than that of Example 1. The reason is that at 14d, Ca2SiO4 in dicalcium silicate can react with CO2 to form CaCO3, and the formed CaCO3 has a mixed structure of calcite and aragonite. The proportion of calcite structure in the formed CaCO3 is large but not completely converted into calcite structure. The inside of the ceramic brick is not completely solidified, and a complete CaCO3 skeleton is formed, but the grain size of calcite does not reach the peak, and the overall compressive strength of the ceramic brick is slightly poor.

[0073] The application discloses a method for preparing high-strength ceramic bricks by solidifying dicalcium silicate and fly ash with CO2, and the preparation steps are as follows: mixing dicalcium silicate and fly ash powder after drying to obtain a mixture, adding an appropriate amount of water to obtain a mixture, injecting the mixture into a mold to form a green body, and then naturally air-drying the green body and curing with CO2 to obtain dicalcium silicate and fly ash-based high-strength ceramic bricks. The application uses dicalcium silicate and fly ash as raw materials to prepare high-strength ceramic bricks by CO2 curing and solidification, effectively solving the high energy consumption problem in the sintering process of traditional ceramic bricks. Compared with ceramic bricks prepared by solidifying pure dicalcium silicate with CO2, the ceramic bricks prepared by the application have higher mechanical strength and compressive strength due to the effective activation of the alkaline environment formed by the hydration of dicalcium silicate to the activity of fly ash and the complementary characteristics of the two elements. At the same time, the application provides a new direction for the comprehensive utilization of CO2 and fly ash, two kinds of bulk industrial waste, and realizes the resource transformation of waste. In summary, the application has the characteristics of simple process, low cost and environmental friendliness.

[0074] In summary, compared with the prior art, the dicalcium silicate and fly ash-based high-strength ceramic bricks and the preparation method thereof provided by the application have the following advantages: (1) The compressive strength of the ceramic brick obtained by curing for 14d in the method of Comparative Example 9 is 64.2 MPa, which is about 50 MPa lower than that of Example 1. The reason is that at 14d, Ca2SiO4 in dicalcium silicate can react with CO2 to form CaCO3, and the formed CaCO3 has a mixed structure of calcite and aragonite. The proportion of calcite structure in the formed CaCO3 is large but not completely converted into calcite structure. The inside of the ceramic brick is not completely solidified, and a complete CaCO3 skeleton is formed, but the grain size of calcite does not reach the peak, and the overall compressive strength of the ceramic brick is slightly poor.

[0075] (2) The products prepared by the application not only maximize the value of gaseous waste and solid waste, but also solve the problems of easy cracking and poor frost resistance of previous ceramic brick products to a certain extent, which has important significance in economy, practicality and environmental protection.

[0076] The above is only a preferred specific embodiment of the application, but the protection scope of the application is not limited thereto, and any changes or replacements within the technical range disclosed by the application can be easily thought of by those skilled in the art, which should be covered within the protection scope of the application.

Claims

1. A method for the production of high strength silicate di-calcium and fly ash based ceramic tiles, characterized by, The method comprises the following steps: S10, mixing the dried dicalcium silicate and fly ash powder uniformly, then adding water and stirring to obtain a mixture; S20, performing a forming treatment on the mixture to form a green body; S30, drying the green body, then curing and solidifying the green body by using CO2 to obtain the dicalcium silicate and fly ash based high-strength ceramic brick.

2. The method of producing dicalcium silicate and fly ash based high strength ceramic tile according to claim 1, characterized in that, The dicalcium silicate and fly ash based high-strength ceramic brick is prepared from the following raw materials in parts by mass: dicalcium silicate 10-90 parts, fly ash 10-90 parts, and water 5 parts.

3. The method of manufacturing dicalcium silicate and fly ash based high strength ceramic tile according to claim 1, characterized in that, In the step S10, the mass ratio of the dicalcium silicate to the fly ash is 10: (1-90).

4. The method of claim 3, wherein the method is characterized by, The dicalcium silicate comprises the following components in percentage by mass: Ca2SiO4 85-90%, CaO 5-10%, MgO 2-3%, Al2O3 1-2%, and Fe2O3 >0% and ≤0.10%; and the particle size D50 of the dicalcium silicate is 14.1 μm.

5. The method of claim 3, wherein the method is characterized by, The fly ash comprises the following components in percentage by mass: SiO2 43.01%, Al2O3 24.21%, Fe2O3 2.51%, and CaO 5.61%; and the particle size D50 of the fly ash is 26.3 μm.

6. The method of producing dicalcium silicate and fly ash based high strength ceramic tile according to claim 1, characterized in that, In the step S20, the forming method is a casting method, and the size of the green body is 20×20×20 mm.

7. The method of producing dicalcium silicate and fly ash based high strength ceramic tile according to claim 1, characterized in that, In the step S30, the curing temperature of the curing and solidifying is 20-60°C, and the curing partial pressure is 1-4 kPa.

8. The method of claim 7, wherein the method is characterized by, In the step S30, the curing temperature is 50°C, and the curing partial pressure is 4 kPa.

9. A high strength silicate based ceramic tile based on dicalcium silicate and fly ash characterized in that, The dicalcium silicate and fly ash based high-strength ceramic brick is prepared by the method according to any one of claims 1-8.

10. The dicalcium silicate and fly ash based high-strength ceramic brick according to claim 9 for use in the field of construction.