High-porosity and high-strength porous brick and preparation method thereof

Abstract

The invention discloses a porous brick with high porosity and high strength. The porous brick is obtained by carbonating, curing and curing porous brick slurry, the porous brick slurry is prepared from the following raw materials in parts by mass: 80 to 90 parts of steel slag, 70 to 120 parts of calcium magnesia, 0.01 to 0.08 part of alkali activator, 0.001 to 0.005 part of ethylenediamine tetraacetic acid, 2 to 5 parts of zeolite powder, 4 to 7 parts of fiber and 8 to 10 parts of water. The chemical components of the steel slag comprise silicon dioxide, aluminum oxide, magnesium oxide and calcium oxide; the calcium magnesite comprises the following components in percentage by mass: 45-65% of 26-40-mesh first-class sand, 5-15% of 40-70-mesh second-class sand and 20-40% of 70-120-mesh third-class sand. According to the high-porosity and high-strength perforated brick provided by the invention, on the premise that cement is not used and the production cost is greatly reduced, the perforated brick has high porosity and high strength at the same time, and the actual use requirements are met.

Description

Technical Field

[0001] The present invention relates to the technical field of porous bricks, in particular to a porous brick with high porosity and high strength and a preparation method thereof. Background Art

[0002] In the field of building materials, porous bricks, as an environmentally friendly material that combines decorative and functional properties, have demonstrated significant advantages in improving indoor air quality, regulating the environment, and controlling noise due to their excellent air permeability, sound absorption, and thermal insulation properties. They are widely used in various fields, including construction, industry, and decoration. However, the production of traditional porous bricks generally relies on cement as the primary binder, which not only drives up production costs but also increases dependence on cement resources.

[0003] At the same time, the steel slag generated in industrial production, as a solid waste, its large accumulation not only occupies precious land resources, but also may cause environmental pollution and other problems. In order to promote resource recycling, reduce production costs and alleviate environmental pressure, researchers have begun to explore new ways to use steel slag to prepare porous bricks. Among them, the chemical composition of steel slag includes silicon dioxide, aluminum oxide, magnesium oxide and calcium oxide, etc.; and magnesium oxide mainly exists in the form of free calcium oxide, and magnesium oxide mainly exists in the form of free magnesium oxide; at the same time, the chemical component of steel slag, calcium oxide, can also form tricalcium silicate (C3S), β-type dicalcium silicate (β-C2S), and γ-type dicalcium silicate (γ-C2S) with its component silicon dioxide. The chemical components of steel slag, calcium oxide, silicon dioxide and aluminum oxide, generate chalcedony (CaO·Al2O3·2SiO2). In addition, In addition, the chemical components of calcium oxide and magnesium oxide in steel slag can also form FeO-CaO-MgO-MnO (RO phase) with other chemical components, so that the mineral components in steel slag are mainly tricalcium silicate, β-type dicalcium silicate, γ-type dicalcium silicate, free calcium oxide, free magnesium oxide, FeO-CaO-MgO-MnO solid solution, etc. Since tricalcium silicate, β-type dicalcium silicate, γ-type dicalcium silicate, free calcium oxide and free magnesium oxide in steel slag have certain hydration activity and carbonation activity, it is beneficial to promote the use of steel slag in the preparation of porous bricks.

[0004] However, the existing technology of using steel slag carbonation to prepare porous bricks has the following defects: (1) Carbonation is difficult to convert tricalcium silicate, β-type dicalcium silicate, γ-type dicalcium silicate, and free calcium oxide into calcium carbonate. 2+ and Mg in free magnesium oxide 2+ Fully participate in the carbonation reaction (i.e. Ca in steel slag 2+ and Mg 2+The dissolution degree of CO2 is limited), resulting in insufficient carbonation of steel slag, which in turn affects the strength of porous bricks; (2) the reaction timing characteristics of carbonation from the outside to the inside make the surface of porous bricks prone to premature densification, hindering the deep penetration of CO2, affecting the full progress of the internal carbonation reaction, and thus weakening the mechanical properties of porous bricks; (3) the utilization degree of the chemical components of silicon dioxide and aluminum oxide in steel slag is limited, and it is difficult to be effectively utilized, which also limits the improvement of the overall strength of porous bricks. That is, the strength of porous bricks obtained by using steel slag in the existing technology is poor and it is difficult to meet the actual use requirements.

[0005] Furthermore, the air permeability and other properties of porous bricks are primarily dependent on their internal pore structure. The higher the porosity, the larger the pores, and the higher the air permeability and filtration function. However, excessively high porosity will reduce the density of the porous brick, affecting its strength. This further makes it difficult for porous bricks produced by carbonation of steel slag to achieve both high porosity and high strength. Summary of the Invention

[0006] The purpose of the present invention is to provide a porous brick with high porosity and high strength, which can achieve both high porosity and high strength without using cement, greatly reducing production costs, and meet actual usage requirements.

[0007] Another object of the present invention is to propose a method for preparing porous bricks with high porosity and high strength. The preparation method is simple and easy to operate, ensuring that the obtained porous bricks have a compressive strength of ≥60MPa, a flexural strength of ≥10MPa, and a porosity of 20-25%, so as to take into account both high porosity and high strength.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] A porous brick with high porosity and high strength is obtained by carbonating, curing and solidifying a porous brick slurry; the porous brick slurry comprises the following raw materials, calculated by weight: 80-90 parts of steel slag, 70-120 parts of calcium magnesium sand, 0.01-0.08 parts of an alkali activator, 0.001-0.005 parts of ethylenediaminetetraacetic acid, 2-5 parts of zeolite powder, 4-7 parts of fiber and 8-10 parts of water;

[0010] The chemical components of the steel slag include silicon dioxide, aluminum oxide, magnesium oxide and calcium oxide; the mineral components of the steel slag include tricalcium silicate, beta-type dicalcium silicate, gamma-type dicalcium silicate, free calcium oxide, free magnesium oxide and calcite;

[0011] Calculated by mass percentage, the calcium-magnesia sand includes 45-65% of a first-class sand material of 26-40 meshes, 5-15% of a second-class sand material of 40-70 meshes, and 20-40% of a third-class sand material of 70-120 meshes.

[0012] Furthermore, the chemical composition of the steel slag, calculated by mass percentage, includes 12-14% silicon dioxide, 40-45% calcium oxide, 3-5% magnesium oxide, 3-5% aluminum oxide, 20-25% iron oxide, 4-6% manganese oxide, 1-2% titanium dioxide, 0-1% potassium oxide, and 2-4% phosphorus pentoxide;

[0013] The particle size of the steel slag is less than 75 μm.

[0014] Furthermore, the alkaline activator includes any one or more combinations of sodium phosphate, sodium aluminate, sodium acetate and sodium carbonate.

[0015] Furthermore, the fibers include polypropylene fibers, polyoxymethylene fibers and natural bamboo fibers, and calculated by mass ratio, the mixing ratio of the polypropylene fibers, the polyoxymethylene fibers and the natural bamboo fibers is (2-3):1:1.

[0016] Furthermore, the raw materials of the porous brick slurry also include mineral powder;

[0017] Calculated by mass, the porous brick slurry includes the following raw materials: 80-90 parts of steel slag, 5-20 parts of mineral powder, 70-120 parts of calcium magnesium sand, 0.01-0.08 parts of alkali activator, 0.001-0.005 parts of ethylenediaminetetraacetic acid, 2-5 parts of zeolite powder, 4-7 parts of fiber and 8-10 parts of water.

[0018] Furthermore, the raw materials of the porous brick slurry also include diatomaceous earth;

[0019] Calculated by mass, the porous brick slurry includes the following raw materials: 80-90 parts of steel slag, 5-20 parts of mineral powder, 70-120 parts of calcium magnesium sand, 0.01-0.08 parts of alkali activator, 0.001-0.005 parts of ethylenediaminetetraacetic acid, 2-5 parts of zeolite powder, 4-7 parts of fiber, 8-10 parts of water and 3-10 parts of diatomaceous earth.

[0020] Furthermore, the raw materials of the porous brick slurry also include a water reducer, an air entraining agent and a foam stabilizer;

[0021] Calculated by mass, the porous brick slurry includes the following raw materials: 80-90 parts of steel slag, 5-20 parts of mineral powder, 70-120 parts of calcium magnesium sand, 0.01-0.08 parts of alkali activator, 0.001-0.005 parts of ethylenediaminetetraacetic acid, 2-5 parts of zeolite powder, 4-7 parts of fiber, 8-10 parts of water, 3-10 parts of diatomaceous earth, 0.5-2 parts of water reducer, 0.005-0.01 parts of air entraining agent and 0.005-0.01 parts of foam stabilizer.

[0022] A method for preparing a porous brick with high porosity and high strength, for preparing the above-mentioned porous brick with high porosity and high strength, comprises the following steps:

[0023] A. dissolving the formulated amount of ethylenediaminetetraacetic acid and the alkaline activator in a portion of the formulated amount of water, and then adding the formulated amount of zeolite powder and stirring evenly to obtain a first mixture;

[0024] B. Evenly mix the formulated amount of mineral powder and diatomaceous earth, then add the formulated amount of water reducer, air entraining agent, foam stabilizer and the remaining formulated amount of water and stir evenly to obtain a second mixture;

[0025] C. After uniformly mixing the first mixture, the second mixture, the formulated amount of steel slag and calcium magnesia sand, adding the formulated amount of fiber, and stirring evenly to obtain a porous brick slurry;

[0026] D. Pour the porous brick slurry into the mold and press it into a brick;

[0027] E. The bricks are cured by carbonation and then solidified to obtain porous bricks with high porosity and high strength, wherein the porous bricks have a thickness of 10 to 30 mm, a compressive strength of ≥60 MPa, a flexural strength of ≥10 MPa, and a porosity of 20 to 25%.

[0028] Furthermore, in step E, the carbonation curing temperature is 40-80° C., the curing time is 2-24 h, the curing pressure is 0.1-0.4 MPa, and the purity of CO 2 is 50-90%.

[0029] Furthermore, in step D, the pressure of the compression molding is 8 to 25 MPa.

[0030] The technical solution provided by the present invention can have the following beneficial effects:

[0031] During carbonation curing, gaseous CO2 rapidly dissolves in the slurry to form carbonic acid, which then dissociates into bicarbonate and carbonate ions. Free calcium oxide, in an aqueous environment, generates calcium hydroxide, which reacts with bicarbonate / carbonate ions to form calcium carbonate crystals. Free magnesium oxide, in an aqueous environment, generates magnesium hydroxide, which reacts with bicarbonate / carbonate ions to form magnesium carbonate crystals. This rapidly and extensively eliminates the free calcium oxide and free magnesium oxide in the slag. This not only eliminates the potential for delayed expansion and cracking caused by the slow hydration of free calcium oxide and free magnesium oxide, but also enhances the strength of the porous brick by filling pores and compacting the matrix. Furthermore, in an aqueous environment, the mineral components of the slag—tricalcium silicate, β-type dicalcium silicate, and γ-type dicalcium silicate—react with bicarbonate / carbonate ions to form silica gel. This silica gel effectively encapsulates and bonds the calcium-magnesia aggregate in the porous brick slurry, enhancing its strength.

[0032] 2. In order to make the Ca in the steel slag 2+ and Mg2+ As far as possible, the technical solution is to add ethylenediaminetetraacetic acid in the porous brick slurry formula, and ethylenediaminetetraacetic acid is used as a chelating agent, which can react with Ca 2+ and Mg 2+ Chelation weakens the Ca-O and Mg-O bonds in the slag mineral components and promotes the 2+ and Mg 2+ The dissolution in the slurry makes the Ca in the slag 2+ and Mg 2+ Participate in the carbonation reaction as much as possible, improve its carbonation degree, and thus increase the strength of the porous bricks, while also further eliminating the problems of delayed expansion and cracking caused by the slow hydration of free calcium oxide and free magnesium oxide.

[0033] 3. This technical solution utilizes the adsorption and release effect of zeolite powder on EDTA, which is not only beneficial to increase the amount of EDTA added in the porous brick slurry so that it can fully exert its chelating effect, but also helps to allow CO2 to fully penetrate into the interior of the porous brick, increase the degree of carbonation reaction, and enhance the strength of the porous brick.

[0034] 4. Zeolite powder can also adsorb CO2 during the carbonation reaction, so that the CO2 that has not yet participated in the reaction first penetrates deeply into the interior of the porous brick. Then, during the reaction, due to the instability of zeolite powder adsorption, the adsorbed CO2 is gradually desorbed and released, realizing the release of CO2 inside the porous brick, causing the steel slag to undergo a carbonation reaction from the inside to the outside. Combined with the original carbonation reaction of the steel slag from the outside to the inside, a double carbonation reaction is achieved, which further improves the degree of carbonation and enhances the mechanical properties of the porous brick. DETAILED DESCRIPTION

[0035] The present technical solution provides a porous brick with high porosity and high strength, which is obtained by carbonation curing and solidification of a porous brick slurry; the porous brick slurry comprises the following raw materials, calculated by weight: 80-90 parts of steel slag, 70-120 parts of calcium magnesium sand, 0.01-0.08 parts of an alkali activator, 0.001-0.005 parts of ethylenediaminetetraacetic acid, 2-5 parts of zeolite powder, 4-7 parts of fiber, and 8-10 parts of water;

[0036] The chemical components of the steel slag include silicon dioxide, aluminum oxide, magnesium oxide and calcium oxide; the mineral components of the steel slag include tricalcium silicate, beta-type dicalcium silicate, gamma-type dicalcium silicate, free calcium oxide, free magnesium oxide and calcite;

[0037] Calculated by mass percentage, the calcium-magnesia sand includes 45-65% of a first-class sand material of 26-40 meshes, 5-15% of a second-class sand material of 40-70 meshes, and 20-40% of a third-class sand material of 70-120 meshes.

[0038] In response to the technical problem that porous bricks obtained by using steel slag in the existing technology are difficult to achieve both high porosity and high strength, this technical solution proposes a porous brick with high porosity and high strength. By designing the proportion of porous brick slurry and optimizing raw materials, the porous brick can achieve both high porosity and high strength without using cement, greatly reducing production costs, and meeting actual usage needs.

[0039] Specifically, the raw materials of the porous brick slurry in this technical solution include steel slag, calcium magnesium sand, an alkali activator, ethylenediaminetetraacetic acid, zeolite powder, fiber and water, and the chemical composition of the steel slag includes silicon dioxide, aluminum oxide, magnesium oxide and calcium oxide. First, since the calcium oxide in the steel slag mainly exists in the form of free calcium oxide and the magnesium oxide mainly exists in the form of free magnesium oxide, the free calcium oxide reacts in an aqueous environment to form calcium hydroxide, and the free magnesium oxide reacts in an aqueous environment to form magnesium hydroxide, which increases the alkalinity of the slurry. During carbonation curing, gaseous CO2 rapidly dissolves in the slurry to form carbonic acid, which then dissociates into bicarbonate and carbonate ions. Free calcium oxide, in an aqueous environment, generates calcium hydroxide, which reacts with bicarbonate / carbonate ions to form calcium carbonate crystals. Free magnesium oxide, in an aqueous environment, generates magnesium hydroxide, which reacts with bicarbonate / carbonate ions to form magnesium carbonate crystals. This rapidly and extensively eliminates the free calcium oxide and free magnesium oxide in the slag. This not only eliminates the potential for delayed expansion and cracking caused by the slow hydration of free calcium oxide and free magnesium oxide, but also enhances the strength of the porous brick by filling pores and compacting the matrix. Furthermore, in an aqueous environment, the mineral components of the slag—tricalcium silicate, β-type dicalcium silicate, and γ-type dicalcium silicate—react with bicarbonate / carbonate ions to form silica gel. This silica gel effectively encapsulates and bonds the calcium-magnesia sand aggregate in the porous brick slurry, enhancing the strength of the brick.

[0040] In addition, although carbonation can make the Ca in tricalcium silicate, β-type dicalcium silicate, γ-type dicalcium silicate, free calcium oxide 2+ and Mg in free oxide 2+ A large amount of Ca in the slag participates in the reaction, but 2+ and Mg 2+ The dissolution degree is limited, and it is still difficult to fully participate in the carbonation reaction, resulting in insufficient carbonation of the steel slag. The strength of the porous bricks obtained is limited and it is difficult to meet the actual use requirements. 2+ and Mg 2+ As far as possible, the technical solution is to add ethylenediaminetetraacetic acid in the porous brick slurry formula, and ethylenediaminetetraacetic acid is used as a chelating agent, which can react with Ca 2+ and Mg 2+ Chelation weakens the Ca-O and Mg-O bonds in the slag mineral components and promotes the2+ and Mg 2+ The dissolution in the slurry makes the Ca in the slag 2+ and Mg 2+ Participate in the carbonation reaction as much as possible, improve its carbonation degree, and thus increase the strength of the porous bricks, while also further eliminating the problems of delayed expansion and cracking caused by the slow hydration of free calcium oxide and free magnesium oxide.

[0041] Furthermore, due to the limited solubility of EDTA in porous brick slurry, it can only be added to the formula in small amounts under normal circumstances. When the amount of EDTA added is too small, its role is limited and the expected effect cannot be achieved. Therefore, in order to increase the amount of EDTA added in the formula, the present technical solution also introduces zeolite powder into the slurry formula. The interior of the zeolite powder is composed of a three-dimensional grid connected by silicon (aluminum) oxygen tetrahedrons, so that there are many regularly shaped cavities and pores connecting the cavities inside the zeolite powder. The above-mentioned cavities and pores provide a large number of adsorption sites, so that the zeolite powder can effectively adsorb EDTA, thereby increasing the amount of EDTA added to the porous brick slurry and ensuring that it can fully exert its chelating effect. At the same time, due to the instability of zeolite powder adsorption, the zeolite powder gradually desorbs and releases the adsorbed EDTA during the reaction. The release of EDTA causes Ca in the steel slag to 2+ and Mg 2+ Gradually dissolving and precipitating to participate in the carbonation reaction can effectively avoid the rapid densification of the porous brick surface due to the excessively fast carbonation reaction rate, which would hinder the further penetration of CO2, allowing CO2 to fully penetrate into the interior of the porous brick, increasing the degree of carbonation reaction, and thus enhancing the strength of the porous brick. That is, the present technical solution utilizes the adsorption and release effect of zeolite powder on EDTA, which is not only conducive to increasing the amount of EDTA added to the porous brick slurry so that it can fully exert its chelating effect, but also helps CO2 to fully penetrate into the interior of the porous brick, increasing the degree of carbonation reaction and enhancing the strength of the porous brick.

[0042] Furthermore, zeolite powder can also adsorb CO2 during the carbonation reaction, so that the CO2 that has not yet participated in the reaction first penetrates deeply into the interior of the porous brick. Then, during the reaction, due to the instability of zeolite powder adsorption, the adsorbed CO2 is gradually desorbed and released, realizing the release of CO2 inside the porous brick, causing the steel slag to undergo a carbonation reaction from the inside to the outside, and then combined with the original carbonation reaction of the steel slag from the outside to the inside, a double carbonation reaction is achieved, further improving the degree of carbonation and enhancing the mechanical properties of the porous brick.

[0043] In addition, due to the limited utilization of the chemical components silicon dioxide and aluminum oxide in steel slag, it is difficult to be effectively utilized, which limits the improvement of the overall strength of the porous bricks. As a result, even if ethylenediaminetetraacetic acid and zeolite powder are added to the porous slurry formula, it is difficult to meet the actual needs. In order to make full use of the chemical components silicon dioxide and aluminum oxide in steel slag, this technical solution also specifically adds an alkaline activator to the slurry formula of the porous bricks, and uses the alkaline activator to react with water to generate hydroxide ions to greatly increase the alkalinity of the slurry system; at the same time, the calcium oxide in the steel slag, which mainly exists in the form of free calcium oxide, and the magnesium oxide, which mainly exists in the form of free magnesium oxide, the calcium hydroxide and magnesium hydroxide generated by the above two components are also conducive to increasing the alkalinity of the system, making the system a strong alkaline system.

[0044] Furthermore, generally, the chemical component silica in steel slag exists as a silica-oxygen network structure, while the chemical component alumina in steel slag exists as an alumina-oxygen network structure. Under the action of strong alkali, the silica chains in the silica-oxygen network and the alumina chains in the alumina-oxygen network depolymerize, generating a large number of depolymerized monomer ions, which fully release the chemical components silica and alumina in the steel slag. This activates the activity of the chemical components silica and alumina in the steel slag. Simultaneously, these monomer ions undergo further polycondensation in the strong alkaline environment to form aluminates and silicates, respectively. These aluminates and silicates react with calcium hydroxide, generated in an aqueous environment by free calcium oxide, tricalcium silicate, β-type dicalcium silicate, and γ-type dicalcium silicate in the steel slag, to form calcium aluminate gel and calcium silicate gel. Furthermore, the aluminates and silicates react with magnesium hydroxide, generated by the reaction of free magnesium oxide in the steel slag, to form magnesium aluminate gel and magnesium silicate gel. The aforementioned gel component can also replace cement as a gelling material to effectively encapsulate and bond the calcium-magnesia sand in the porous brick slurry formula, ensuring the strength of the porous brick slurry after curing and imparting higher strength to the porous bricks. Specifically, by adding an alkali activator to the formula, the alkali activator not only further utilizes the chemical components calcium oxide and magnesium oxide in the steel slag, but also the chemical components aluminum oxide and silicon dioxide in the steel slag, thereby enhancing the hydration activity of the steel slag and contributing to increased strength of the porous bricks.

[0045] It should be noted that the addition of an alkaline activator in this technical solution greatly improves the alkaline environment of the porous brick slurry, which is also beneficial to promote the dissolution and carbonation reaction of gaseous CO2 in the slurry, and is also beneficial to improving the strength of the porous bricks.

[0046] Secondly, although using the carbonation and alkali excitation of steel slag to increase hydration activity is beneficial to improving its strength, when the strength is too high and the toughness is insufficient, it is easy to cause it to break under the action of external forces. Therefore, this technical solution also adds fibers to the raw material formula of the porous brick slurry. The fibers themselves have excellent flexibility and can form a network structure inside the porous bricks, effectively dispersing and transmitting stress, reducing the concentrated stress points caused by external forces, thereby enhancing the flexibility and crack resistance of the porous bricks and ensuring the overall strength of the porous bricks.

[0047] Again, the porous brick slurry in this technical solution also includes calcium-magnesia sand, wherein the calcium-magnesia sand includes 45-65% of Class I sand of 26-40 mesh, 5-15% of Class II sand of 40-70 mesh and 20-40% of Class III sand of 70-120 mesh. The combination of sands of different mesh sizes not only constructs the skeleton structure of the porous brick, but also helps to improve the porosity of the porous brick through reasonable proportioning. The increase in porosity not only facilitates the penetration of external CO2 into the interior of the porous brick, but also increases the surface area of ​​the steel slag carbonation reaction, thereby increasing the degree of the steel slag carbonation reaction, so that the porous brick has both high porosity and high strength.

[0048] Finally, the porous brick slurry includes the following raw materials, calculated by weight: 80-90 parts steel slag, 70-120 parts calcium magnesia sand, 0.01-0.08 parts alkali activator, 0.001-0.005 parts EDTA, 2-5 parts zeolite powder, 4-7 parts fiber, and 8-10 parts water. Steel slag is the primary raw material, and its carbonation and alkali activation enhance its hydration activity, which helps improve the strength of the porous brick. Therefore, its addition is relatively large. Calcium magnesia sand is used as an aggregate. The combination of sands of different mesh sizes not only builds the skeleton structure of the porous brick, but also forms voids through a reasonable ratio. Therefore, its addition is also relatively large to ensure high porosity. A small amount of alkali activator and EDTA additives can achieve the desired effect. Fiber enhances the flexibility and crack resistance of the porous brick, and its addition is limited to ensure the effect.

[0049] Therefore, this technical solution uses the coordinated action of steel slag, calcium magnesium sand, alkali activator, ethylenediaminetetraacetic acid, zeolite powder, fiber and water to alkali activate and carbonate the steel slag, which not only turns waste into treasure and improves the utilization rate of steel slag, but also makes full and effective use of the components in the steel slag, so that the porous bricks can have both high porosity and high strength without using cement, greatly reducing production costs, and meeting actual use needs.

[0050] It is further explained that, calculated by mass percentage, the chemical composition of the steel slag includes 12-14% silicon dioxide, 40-45% calcium oxide, 3-5% magnesium oxide, 3-5% aluminum oxide, 20-25% iron oxide, 4-6% manganese oxide, 1-2% titanium dioxide, 0-1% potassium oxide and 2-4% phosphorus pentoxide;

[0051] The particle size of the steel slag is less than 75 μm.

[0052] The present technical solution preferably adds steel slag having a silica content of 12-14%, an alumina content of 3-5%, a calcium oxide content of 40-45% and a magnesium oxide content of 3-5% calculated by mass to the porous brick slurry formula, so that the total content of silica, alumina, calcium oxide and magnesium oxide in the porous brick slurry formula reaches 58-69%, which is beneficial to improving the carbonation and hydration degree of the steel slag and improving the strength of the porous bricks.

[0053] Preferably, calculated by mass percentage, the chemical composition of the steel slag includes 13.8% silicon dioxide, 43.6% calcium oxide, 4.8% magnesium oxide, 4.1% aluminum oxide, 24.6% iron oxide, 5.2% manganese oxide, 1.1% titanium dioxide, 0.5% potassium oxide and 2.3% phosphorus pentoxide.

[0054] Furthermore, in this technical solution, the particle size of steel slag is limited to <75μm, which is beneficial to improving its utilization rate, stimulating its activity, and improving the strength of porous bricks; on the other hand, it is beneficial to ensure the fineness of the formed porous bricks, avoid the surface of the porous bricks being too rough, and ensure the appearance of the product.

[0055] It is further described that the alkaline activator includes any one or more combinations of sodium phosphate, sodium aluminate, sodium acetate and sodium carbonate.

[0056] Sodium phosphate, sodium aluminate, sodium acetate, and sodium carbonate all hydrolyze in an aqueous environment to produce hydroxide ions, significantly increasing the alkalinity of the porous brick slurry. Therefore, in this technical solution, the preferred alkali activator includes a combination of one or more of sodium phosphate, sodium aluminate, sodium acetate, and sodium carbonate, which helps enhance the hydration activity of steel slag in a strong alkaline environment.

[0057] In addition, when sodium phosphate is used as an activator, the phosphate ions can also promote the dissolution and polymerization of aluminosilicates in the steel slag, forming a compound with gelling properties, calcium magnesium sand, which is better for wrapping and bonding. When sodium aluminate is used as an activator, it can also hydrolyze to form sodium metaaluminate, which can react with calcium, silicon and other components in the steel slag to form gelling substances such as calcium aluminum silicate, calcium magnesium sand, which is better for wrapping and bonding. At the same time, when sodium carbonate is used as an activator, carbonate ions can react with calcium and magnesium ions to form carbonate precipitates. The above precipitates play a filling and strengthening role in the slurry.

[0058] It is further explained that the fibers include polypropylene fibers, polyoxymethylene fibers and natural bamboo fibers, and calculated by mass ratio, the mixing ratio of the polypropylene fibers, the polyoxymethylene fibers and the natural bamboo fibers is (2-3):1:1.

[0059] Polypropylene fiber has excellent tensile strength and weather resistance. It can be effectively dispersed in the slurry to form a three-dimensional network structure, thereby improving the overall strength and toughness of the porous brick. In addition, polypropylene fiber also has good acid and alkali resistance and corrosion resistance, and can be used in various environments. Polyformaldehyde fiber has high strength and high modulus, which can significantly enhance the rigidity and deformation resistance of porous bricks; natural bamboo fiber not only has good tensile strength and toughness, but also has certain antibacterial and mildew resistance. Therefore, the present technical solution preferably includes polypropylene fiber, polyformaldehyde fiber and natural bamboo fiber, and limits the mixing ratio of polypropylene fiber, polyformaldehyde fiber and natural bamboo fiber, so that the fiber obtained by using the above mixing ratio can not only improve the strength and toughness of the porous brick, but also help to improve the antibacterial, mildew resistance and durability of the porous brick.

[0060] It is further explained that the raw materials of the porous brick slurry also include mineral powder;

[0061] Calculated by mass, the porous brick slurry includes the following raw materials: 80-90 parts of steel slag, 5-20 parts of mineral powder, 70-120 parts of calcium magnesium sand, 0.01-0.08 parts of alkali activator, 0.001-0.005 parts of ethylenediaminetetraacetic acid, 2-5 parts of zeolite powder, 4-7 parts of fiber and 8-10 parts of water.

[0062] The raw materials of the porous slurry preferably include mineral powder. The chemical components such as silica, alumina and calcium oxide contained in the mineral powder can react with calcium hydroxide generated by alkali excitation and carbonation reaction of steel slag to generate calcium aluminate gel and calcium silicate gel; in addition, the chemical components such as silica, alumina and calcium oxide contained in the mineral powder can also react with magnesium hydroxide generated by alkali excitation and carbonation reaction of steel slag to generate magnesium aluminate gel and magnesium silicate gel. Calcium aluminate gel, calcium silicate gel, magnesium aluminate gel and magnesium silicate gel can replace cement as a cementitious material to better wrap and bond the calcium-magnesium sand in the porous brick slurry formula, thereby improving the compressive strength and flexural strength of the porous bricks.

[0063] It should be noted that, in the present technical solution, the chemical composition of the mineral powder, calculated by mass percentage, includes 39.40% silicon dioxide, 20.11% aluminum oxide, 3.57% iron oxide, 25.77% calcium oxide, 5.56% magnesium oxide, 1.40% titanium dioxide, 1.5% sulfur trioxide, 0.78% potassium oxide, and 0.69% sodium oxide.

[0064] It is further explained that the raw materials of the porous brick slurry also include diatomaceous earth;

[0065] Calculated by mass, the porous brick slurry includes the following raw materials: 80-90 parts of steel slag, 5-20 parts of mineral powder, 70-120 parts of calcium magnesium sand, 0.01-0.08 parts of alkali activator, 0.001-0.005 parts of ethylenediaminetetraacetic acid, 2-5 parts of zeolite powder, 4-7 parts of fiber, 8-10 parts of water and 3-10 parts of diatomaceous earth.

[0066] Diatomaceous earth has high porosity and low bulk density, and has excellent thermal insulation and heat preservation properties. Therefore, this technical solution preferably adds diatomaceous earth to the porous brick slurry formula, thereby reducing the bulk density of the porous brick while increasing the porosity of the porous brick, ensuring the porous brick's air permeability, moisture absorption and thermal insulation properties.

[0067] It is further explained that the raw materials of the porous brick slurry also include a water reducer, an air entraining agent and a foam stabilizer;

[0068] Calculated by mass, the porous brick slurry includes the following raw materials: 80-90 parts of steel slag, 5-20 parts of mineral powder, 70-120 parts of calcium magnesium sand, 0.01-0.08 parts of alkali activator, 0.001-0.005 parts of ethylenediaminetetraacetic acid, 2-5 parts of zeolite powder, 4-7 parts of fiber, 8-10 parts of water, 3-10 parts of diatomaceous earth, 0.5-2 parts of water reducer, 0.005-0.01 parts of air entraining agent and 0.005-0.01 parts of foam stabilizer.

[0069] Under the premise of ensuring the fluidity of porous brick slurry and improving the strength of porous bricks, water reducers can reduce the use of water in the porous brick slurry formula, thereby reducing negative effects such as shrinkage cracks of porous bricks and improving the durability of the base layer; the tiny bubbles produced by air entraining agents are not only beneficial to increasing the porosity of porous bricks, but also beneficial to reducing the shrinkage and swelling stress of porous brick slurry, improving its durability and crack resistance; foam stabilizers are beneficial to reducing the surface tension of porous brick slurry, stabilizing bubbles, ensuring the formation of a small and uniform porous structure as a whole, improving the porosity, pore distribution uniformity and overall strength of porous bricks, and meeting different usage requirements. Therefore, in this technical solution, water reducers, air entraining agents and foam stabilizers are preferably added to the porous brick slurry formula to increase the porosity while ensuring strength, and further to achieve both high strength and high porosity.

[0070] Preferably, the water reducer is a polycarboxylate water reducer; the air entraining agent is calcium lignin sulfonate; and the foam stabilizer is sodium dodecylbenzene sulfonate.

[0071] A method for preparing a porous brick with high porosity and high strength, for preparing the above-mentioned porous brick with high porosity and high strength, comprises the following steps:

[0072] A. dissolving the formulated amount of ethylenediaminetetraacetic acid and the alkaline activator in a portion of the formulated amount of water, and then adding the formulated amount of zeolite powder and stirring evenly to obtain a first mixture;

[0073] B. Evenly mix the formulated amount of mineral powder and diatomaceous earth, then add the formulated amount of water reducer, air entraining agent, foam stabilizer and the remaining formulated amount of water and stir evenly to obtain a second mixture;

[0074] C. After uniformly mixing the first mixture, the second mixture, the formulated amount of steel slag and calcium magnesia sand, adding the formulated amount of fiber, and stirring evenly to obtain a porous brick slurry;

[0075] D. Pour the porous brick slurry into the mold and press it into a brick;

[0076] E. The bricks are cured by carbonation and then solidified to obtain porous bricks with high porosity and high strength, wherein the porous bricks have a thickness of 10 to 30 mm, a compressive strength of ≥60 MPa, a flexural strength of ≥10 MPa, and a porosity of 20 to 25%.

[0077] This technical solution also proposes a method for preparing porous bricks with high porosity and high strength, which has simple steps and strong operability, and is conducive to ensuring the relevant properties of the porous bricks during the preparation process.

[0078] Specifically, traditional porous bricks must be at least 90 mm thick to ensure the excellent performance of the porous bricks. However, if the porous brick slurry of this technical solution is used to prepare porous bricks, the thickness only needs to reach 10 to 30 mm to achieve compressive strength ≥ 60 MPa, flexural strength ≥ 10 MPa, and a porosity of 20 to 25%, which greatly saves costs.

[0079] Further, in step E, the carbonation curing temperature is 40-80°C, the curing time is 2-24 hours, the curing pressure is 0.1-0.4 MPa, and the purity of CO2 is 50-90%.

[0080] When the curing temperature, curing pressure and CO2 purity are too high, the carbonation rate will be too fast, the surface of the porous brick will be densified too early, and thus the deep penetration of CO2 will be hindered. When the curing temperature, curing pressure and CO2 purity are too low, the reaction rate will be too slow, affecting production efficiency. In order to improve the degree of carbonation reaction, the present technical solution specifically limits the curing temperature of carbonation curing to 40-80°C, the curing pressure to 0.1-0.4MPa, and the CO2 purity to 50-90%. This ensures that CO2 can fully penetrate into the interior of the porous brick, improves the degree of carbonation reaction, and ensures production efficiency and reduces production costs while ensuring the strength of the porous brick.

[0081] Furthermore, if the curing time is insufficient, the carbonation level will decrease; if the curing time is too long, the carbonation level will not increase significantly. Therefore, this technical solution limits the curing time to 2 to 24 hours, thereby improving production efficiency while increasing the carbonation level and the strength of the porous bricks.

[0082] Further description, in step D, the pressure of the pressing molding is 8 to 25 MPa.

[0083] When the pressure during the press molding process is too low, the porous brick slurry cannot be fully compacted, resulting in a large number of voids and loosely bonded areas inside the brick body, which not only affects the smoothness of the brick body but also reduces its overall strength. When the press molding pressure is too high, the excessive pressure will force the raw materials in the porous brick slurry to be arranged more tightly, thereby reducing the porosity of the brick body. However, if the porosity is too low, the surface area for the carbonation reaction will be reduced, affecting the degree of carbonation. Therefore, the present technical solution ensures that it has both high porosity and high strength by limiting the press molding pressure.

[0084] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0085] Example 1

[0086] In this embodiment, the porous brick slurry includes the following raw materials calculated by mass: 80 parts of 60μm steel slag, 80 parts of calcium magnesium sand, 0.05 parts of sodium carbonate, 0.003 parts of ethylenediaminetetraacetic acid, 3 parts of zeolite powder, 5 parts of fiber and 8 parts of water; calculated by mass percentage, the chemical composition of the steel slag includes 13.8% silicon dioxide, 43.6% calcium oxide, 4.8% magnesium oxide, 4.1% aluminum oxide, 24.6% iron oxide, 5.2% manganese oxide, 1.1% titanium dioxide, 0.5% potassium oxide and 2.3% phosphorus pentoxide; the mineral components of the steel slag include tricalcium silicate, β-type dicalcium silicate, γ-type dicalcium silicate, free calcium oxide, free magnesium oxide and yttrium feldspar; calculated by mass percentage, the calcium-magnesium sand includes 50% Class I sand of 26-40 mesh, 10% Class II sand of 40-70 mesh and 40% Class III sand of 70-120 mesh; calculated by mass ratio, the mixing ratio of polypropylene fiber, polyoxymethylene fiber and natural bamboo fiber in the fiber is 2:1:1.

[0087] The method for preparing the porous brick with high porosity and high strength in this embodiment comprises the following steps:

[0088] A. dissolving the formulated amount of ethylenediaminetetraacetic acid and sodium carbonate in 50% of the formulated amount of water, then adding the formulated amount of zeolite powder and stirring evenly to obtain a first mixed material;

[0089] B. mixing the formulated amount of diatomaceous earth and 50% of the formulated amount of water to obtain a second mixture;

[0090] C. After uniformly mixing the first mixed material, the second mixed material, the formulated amount of 60 μm steel slag, 26-40 mesh first-class sand material, 40-70 mesh second-class sand material and 70-120 mesh third-class sand material, the formulated amount of polypropylene fiber, polyoxymethylene fiber and natural bamboo fiber are added, and the porous brick slurry is obtained after uniform mixing;

[0091] D. Pour the porous brick slurry into a mold and press it under 15 MPa to obtain a brick;

[0092] E. The bricks are carbonated and cured under the conditions of a curing temperature of 50° C., a curing time of 12 h, a curing pressure of 0.2 MPa, and a CO2 purity of 70%, and then cured to obtain porous bricks with high porosity and high strength.

[0093] Example 2

[0094] The porous brick slurry includes the following raw materials calculated by weight: 90 parts of 50μm steel slag, 15 parts of mineral powder, 100 parts of calcium magnesium sand, 0.05 parts of sodium aluminate, 0.003 parts of ethylenediaminetetraacetic acid, 5 parts of zeolite powder, 5 parts of fiber, 8 parts of water, 7 parts of diatomaceous earth, 1.5 parts of polycarboxylic acid water reducer, 0.008 parts of calcium lignin sulfonate and 0.008 parts of sodium dodecylbenzene sulfonate; the chemical composition of the steel slag includes 13.8% of silicon dioxide, 43.6% of calcium oxide, 4.8% of magnesium oxide, 4.1% of aluminum oxide and 0.02% of iron sesquioxide. 24.6%, manganese oxide 5.2%, titanium dioxide 1.1%, potassium oxide 0.5% and phosphorus pentoxide 2.3%; the mineral components of the steel slag include tricalcium silicate, β-type dicalcium silicate, γ-type dicalcium silicate, free calcium oxide, free magnesium oxide and yttrium feldspar; calculated by mass percentage, the calcium-magnesia sand includes 65% of Class I sand with 26-40 mesh, 10% of Class II sand with 40-70 mesh and 25% of Class III sand with 70-120 mesh; calculated by mass ratio, the mixing ratio of polypropylene fiber, polyoxymethylene fiber and natural bamboo fiber in the fiber is 2.5:1:1.

[0095] The method for preparing the porous brick with high porosity and high strength in this embodiment comprises the following steps:

[0096] A. dissolving the formulated amount of ethylenediaminetetraacetic acid and sodium aluminate in 30% of the formulated amount of water, and then adding the formulated amount of zeolite powder and stirring evenly to obtain a first mixture;

[0097] B. mixing the formulated amount of mineral powder and diatomaceous earth, and then adding the formulated amount of polycarboxylate water reducer, calcium lignin sulfonate, sodium dodecylbenzene sulfonate and 70% of the formulated amount of water and stirring evenly to obtain a second mixture;

[0098] C. After uniformly mixing the first mixed material, the second mixed material, the formulated amount of 50 μm steel slag, 26-40 mesh first-class sand material, 40-70 mesh second-class sand material and 70-120 mesh third-class sand material, the formulated amount of polypropylene fiber, polyoxymethylene fiber and natural bamboo fiber are added, and the porous brick slurry is obtained after uniform mixing;

[0099] D. Pour the porous brick slurry into a mold and press it under 10 MPa to obtain a brick;

[0100] E. The bricks are carbonated and cured under the conditions of a curing temperature of 60° C., a curing time of 15 h, a curing pressure of 0.2 MPa, and a CO2 purity of 60%, and then cured to obtain porous bricks with high porosity and high strength.

[0101] Example 3

[0102] The porous brick slurry includes the following raw materials calculated by weight: 85 parts of 35μm steel slag, 20 parts of mineral powder, 90 parts of calcium magnesium sand, 0.03 parts of sodium phosphate, 0.005 parts of ethylenediaminetetraacetic acid, 3 parts of zeolite powder, 7 parts of fiber, 10 parts of water, 10 parts of diatomaceous earth, 2 parts of polycarboxylic acid water reducer, 0.01 parts of calcium lignin sulfonate and 0.005 parts of sodium dodecylbenzene sulfonate; the chemical composition of the steel slag includes 13.8% of silicon dioxide, 43.6% of calcium oxide, 4.8% of magnesium oxide, 4.1% of aluminum oxide and 0.02% of iron oxide. 24.6%, manganese oxide 5.2%, titanium dioxide 1.1%, potassium oxide 0.5% and phosphorus pentoxide 2.3%; the mineral components of the steel slag include tricalcium silicate, β-type dicalcium silicate, γ-type dicalcium silicate, free calcium oxide, free magnesium oxide and yttrium feldspar; calculated by mass percentage, the calcium-magnesia sand includes 45% of Class I sand of 26-40 mesh, 15% of Class II sand of 40-70 mesh and 40% of Class III sand of 70-120 mesh; calculated by mass ratio, the mixing ratio of polypropylene fiber, polyoxymethylene fiber and natural bamboo fiber in the fiber is 3:1:1.

[0103] The method for preparing the porous brick with high porosity and high strength in this embodiment comprises the following steps:

[0104] A. dissolving the formulated amount of ethylenediaminetetraacetic acid and sodium phosphate in 40% of the formulated amount of water, and then adding the formulated amount of zeolite powder and stirring evenly to obtain a first mixture;

[0105] B. mixing the formulated amount of mineral powder and diatomaceous earth uniformly, then adding the formulated amount of polycarboxylate water reducer, calcium lignin sulfonate, sodium dodecylbenzene sulfonate and 60% of the formulated amount of water and stirring uniformly to obtain a second mixture;

[0106] C. After uniformly mixing the first mixed material, the second mixed material, the formulated amount of 35 μm steel slag, 26-40 mesh first-class sand material, 40-70 mesh second-class sand material and 70-120 mesh third-class sand material, the formulated amount of polypropylene fiber, polyoxymethylene fiber and natural bamboo fiber are added, and the porous brick slurry is obtained after uniform mixing;

[0107] D. Pour the porous brick slurry into a mold and press it at 20 MPa to obtain a brick;

[0108] E. The bricks are carbonated and cured under the conditions of a curing temperature of 40° C., a curing time of 20 h, a curing pressure of 0.2 MPa, and a CO2 purity of 80%, and then cured to obtain porous bricks with high porosity and high strength.

[0109] Comparative Example 1

[0110] The preparation method and raw materials of Comparative Example 1 are the same as those of Example 2, except that no steel slag is added to the porous brick slurry formula in Comparative Example 1.

[0111] Comparative Example 2

[0112] The preparation method and raw materials of Comparative Example 2 are the same as those of Example 2, except that the alkali activator sodium aluminate is not added to the porous brick slurry formula in Comparative Example 2.

[0113] Comparative Example 3

[0114] The preparation method and raw materials of Comparative Example 3 are the same as those of Example 2, except that EDTA is not added to the porous brick slurry formula in Comparative Example 3.

[0115] Comparative Example 4

[0116] The preparation method and raw materials of Comparative Example 4 are the same as those of Example 2, except that no zeolite powder is added to the porous brick slurry formula in Comparative Example 4.

[0117] The porous bricks were prepared by the preparation methods in the above embodiment and comparative example respectively. The thickness of the porous bricks was measured using a vernier caliper. The flexural strength and compressive strength of the porous bricks were tested using the test standard of "GB / T 35160 Test Methods for Synthetic Stone". The porosity of the porous bricks was measured using the immersion method. The results are shown in Table 1 below.

[0118] Table 1 Test results of relevant properties of porous bricks

[0119] Experiment number Thickness (mm) Compressive strength (MPa) Flexural strength (MPa) Porosity (%) Example 1 18.14 61.72 10.83 21.17 Example 2 20.78 63.58 11.54 22.45 Example 3 25.35 62.30 10.11 23.21 Comparative Example 1 20.72 37.74 6.26 21.66 Comparative Example 2 20.69 38.15 7.13 22.07 Comparative Example 3 20.74 52.58 9.35 22.37 Comparative Example 4 20.73 49.22 9.03 22.40

[0120] From the performance test results in Table 1, it can be seen that the porous bricks prepared by the method for preparing porous bricks with high porosity and high strength in this technical solution have a compressive strength ≥60MPa, a flexural strength ≥10MPa, and a porosity of 20-25%. It can take into account both high porosity and high strength at the same time and meet the use requirements.

[0121] In Comparative Example 1, since no steel slag was added, the strength of the porous brick slurry deteriorated, thereby affecting the strength of the porous bricks.

[0122] In Comparative Example 2, since the alkaline activator sodium aluminate was not added, the hydration activity of the steel slag was not activated, thereby affecting the strength of the porous bricks.

[0123] Comparative Example 3 did not add EDTA, resulting in Ca in the steel slag. 2+ and Mg 2+ The degree of precipitation is limited, and the degree of carbonation is limited, which affects the strength of the porous bricks.

[0124] In Comparative Example 4, since no zeolite powder was added, the adsorption and release effects of the zeolite powder could not be utilized, which also affected the strength of the porous brick.

[0125] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are intended solely to illustrate the principles of the present invention and are not to be construed in any way as limiting the scope of protection of the present invention. Based on the explanations herein, those skilled in the art will readily conceive of other specific embodiments of the present invention without inventive effort, and such embodiments will fall within the scope of protection of the present invention.

Claims

1. A porous brick with high porosity and high strength, characterized in that: The porous brick slurry is obtained by carbonation curing and solidification; the porous brick slurry includes the following raw materials calculated by weight: 80-90 parts of steel slag, 70-120 parts of calcium magnesium sand, 0.01-0.08 parts of alkali activator, 0.001-0.005 parts of ethylenediaminetetraacetic acid, 2-5 parts of zeolite powder, 4-7 parts of fiber and 8-10 parts of water; The chemical components of the steel slag include silicon dioxide, aluminum oxide, magnesium oxide and calcium oxide; the mineral components of the steel slag include tricalcium silicate, beta-type dicalcium silicate, gamma-type dicalcium silicate, free calcium oxide, free magnesium oxide and pyrite; Calculated by mass percentage, the calcium-magnesium sand includes 45-65% of first-class sand material of 26-40 meshes, 5-15% of second-class sand material of 40-70 meshes and 20-40% of third-class sand material of 70-120 meshes.

2. A porous brick with high porosity and high strength according to claim 1, characterized in that: Calculated by mass percentage, the chemical composition of the steel slag includes 12-14% silicon dioxide, 40-45% calcium oxide, 3-5% magnesium oxide, 3-5% aluminum oxide, 20-25% iron oxide, 4-6% manganese oxide, 1-2% titanium dioxide, 0-1% potassium oxide and 2-4% phosphorus pentoxide; The particle size of the steel slag is less than 75 μm.

3. A porous brick with high porosity and high strength according to claim 1, characterized in that: The alkaline activator includes any one or more combinations of sodium phosphate, sodium aluminate, sodium acetate and sodium carbonate.

4. The porous brick with high porosity and high strength according to claim 1, characterized in that: The fibers include polypropylene fibers, polyoxymethylene fibers and natural bamboo fibers, and calculated by mass ratio, the mixing ratio of the polypropylene fibers, the polyoxymethylene fibers and the natural bamboo fibers is (2-3):1:

1.

5. The porous brick with high porosity and high strength according to claim 1, characterized in that: The raw materials of the porous brick slurry also include mineral powder; Calculated by weight, the porous brick slurry includes the following raw materials: 80-90 parts of steel slag, 5-20 parts of mineral powder, 70-120 parts of calcium magnesium sand, 0.01-0.08 parts of alkali activator, 0.001-0.005 parts of ethylenediaminetetraacetic acid, 2-5 parts of zeolite powder, 4-7 parts of fiber and 8-10 parts of water.

6. The porous brick with high porosity and high strength according to claim 5, characterized in that: The raw materials of the porous brick slurry also include diatomaceous earth; Calculated by weight, the porous brick slurry includes the following raw materials: 80-90 parts of steel slag, 5-20 parts of mineral powder, 70-120 parts of calcium magnesium sand, 0.01-0.08 parts of alkali activator, 0.001-0.005 parts of ethylenediaminetetraacetic acid, 2-5 parts of zeolite powder, 4-7 parts of fiber, 8-10 parts of water and 3-10 parts of diatomaceous earth.

7. The porous brick with high porosity and high strength according to claim 6, characterized in that: The raw materials of the porous brick slurry also include a water reducing agent, an air entraining agent and a foam stabilizer; Calculated by mass, the porous brick slurry includes the following raw materials: 80-90 parts of steel slag, 5-20 parts of mineral powder, 70-120 parts of calcium magnesium sand, 0.01-0.08 parts of alkali activator, 0.001-0.005 parts of ethylenediaminetetraacetic acid, 2-5 parts of zeolite powder, 4-7 parts of fiber, 8-10 parts of water, 3-10 parts of diatomaceous earth, 0.5-2 parts of water reducer, 0.005-0.01 parts of air entraining agent and 0.005-0.01 parts of foam stabilizer.

8. A method for preparing porous bricks with high porosity and high strength, characterized in that: The method for preparing the porous brick with high porosity and high strength as claimed in claim 7 comprises the following steps: A. dissolving a formulated amount of ethylenediaminetetraacetic acid and an alkaline activator in a portion of the formulated amount of water, and then adding a formulated amount of zeolite powder and stirring evenly to obtain a first mixed material; B. Evenly mix the formulated amount of mineral powder and diatomaceous earth, then add the formulated amount of water reducer, air entraining agent, foam stabilizer and the remaining formulated amount of water and stir evenly to obtain a second mixture; C. After the first mixture, the second mixture, the formula amount of steel slag and calcium magnesium sand are mixed evenly, the formula amount of fiber is added, and the porous brick slurry is obtained after stirring evenly; D. Pour the porous brick slurry into the mold and press it into a brick blank; E. The brick blank is cured by carbonation and then solidified to obtain a porous brick with high porosity and high strength, wherein the porous brick has a thickness of 10 to 30 mm, a compressive strength of ≥60 MPa, a flexural strength of ≥10 MPa, and a porosity of 20 to 25%.

9. The method for preparing a porous brick with high porosity and high strength according to claim 8, characterized in that: In step E, the carbonation curing temperature is 40-80° C., the curing time is 2-24 h, the curing pressure is 0.1-0.4 MPa, and the purity of CO2 is 50-90%.

10. The method for preparing a porous brick with high porosity and high strength according to claim 8, characterized in that: In step D, the pressure of the compression molding is 8 to 25 MPa.