A preparation process for high-strength cement-based unburned pavement bricks

Abstract

The present invention relates to the technical field of pavement brick preparation, and specifically discloses a preparation process for high-strength cement-based unfired pavement bricks, comprising the following steps: (1) mixing glass powder, shell powder, basalt fiber, sodium silicate and water to form a coating slurry. (2) adding the coating slurry to steel slag coarse aggregate, mixing the obtained coarse aggregate, placing it in shell powder for re-coating, and then sintering it to obtain pre-modified steel slag coarse aggregate. (3) soaking the pre-modified steel slag coarse aggregate in an acid solution, separating the coarse aggregate after completion, washing it, adding it to an alkaline suspension of graphene oxide, heating and keeping it warm, to obtain modified steel slag coarse aggregate. (4) preparing cement-based unfired pavement bricks using silicate cement, modified steel slag coarse aggregate, river sand fine aggregate, etc. as raw materials. The steel slag aggregate prepared by the process of the present invention has better bonding strength with the unfired pavement brick matrix, eliminates the problem of poor volume stability of the steel slag aggregate, and improves the strength and service life of the unfired pavement bricks.

Description

Technical Field

[0001] The present invention relates to the technical field of pavement brick preparation, and in particular to a preparation process of high-strength cement-based unfired pavement bricks. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] Cement-based unfired bricks are made by mixing raw materials such as industrial waste and construction debris with cement binders and then subjecting them to molding and curing processes. Unlike traditional fired bricks, they do not require high-temperature kiln firing, hence the name "unfired" bricks. The production of unfired bricks not only helps recycle industrial solid waste but also reduces energy consumption and carbon emissions, making them a more environmentally friendly and low-carbon product than fired bricks. Currently, cement-based unfired bricks are widely used in paving various roads, such as sidewalks, driveways, plazas, and parking lots.

[0004] Steel slag is a type of waste residue produced during the steelmaking process. It is not only strong but also wear-resistant. my country's steel production ranks among the highest in the world, which has also brought in a large amount of steel slag. Using steel slag as aggregate and using it in the preparation of cement-based unfired bricks is a feasible way to utilize solid waste. However, since steel slag contains free calcium oxide and magnesium oxide, it reacts with water to produce volume expansion, which easily forms internal stress in the unfired bricks. When this internal stress exceeds the strength of the unfired bricks, cracks will occur, leading to the deterioration of the strength of the unfired bricks. In addition, due to the low reactivity of steel slag, its bonding strength with the unfired brick matrix is insufficient. During service, the steel slag particles on the surface of the unfired bricks are prone to gradual peeling and falling off under the action of external forces such as friction, resulting in a decrease in the service life of the unfired bricks. Summary of the Invention

[0005] To address these issues, the present invention discloses a process for preparing high-strength cement-based, unfired paving bricks. The steel slag aggregate produced in this process exhibits improved bonding strength with the brick matrix, while also eliminating the inherent problem of poor volume stability, thereby increasing the strength and service life of the unfired paving bricks. Specifically, the technical solution of the present invention is as follows.

[0006] A preparation process for high-strength cement-based unburned paving bricks comprises the following steps:

[0007] (1) Mix glass powder, shell powder, chopped basalt fiber, sodium silicate and water and stir evenly to form a coating slurry for later use.

[0008] (2) Adding the coating slurry to the steel slag coarse aggregate, mixing them evenly, placing the obtained coarse aggregate in shell powder for coating again, and then sintering the obtained coated steel slag coarse aggregate at a temperature higher than the softening temperature of the glass powder. After completion, cooling is performed to obtain pre-modified steel slag coarse aggregate for standby use.

[0009] (3) Soaking the pre-modified steel slag coarse aggregate in an acid solution, separating the coarse aggregate after completion, washing it, adding it to an alkaline suspension of graphene oxide, and heating and keeping it warm. After the reaction is complete, the modified steel slag coarse aggregate is obtained and set aside.

[0010] (4) Portland cement, the modified steel slag coarse aggregate, river sand fine aggregate, fly ash, mineral powder, flexible fiber yarn, and water reducer are taken as raw materials, the raw materials are mixed evenly, and water is added to mix evenly, the obtained slurry is poured into a mold and pressed into shape, and the mold is demoulded and cured to obtain cement-based unburned pavement bricks.

[0011] Furthermore, in step (1), the mass ratio of the glass powder, shell powder, chopped basalt fiber, and sodium silicate is 2.8-3.5:2:1.2-1.8:0.7-0.9. Optionally, the chopped basalt fiber has a length of 5-10 mm and a diameter of 0.2-0.5 mm. The fineness of the glass powder and shell powder is 300-400 mesh.

[0012] Furthermore, in step (1), water is added according to the solid content of the coating slurry being 40-50 wt.%.

[0013] Furthermore, in step (2), the ratio of the steel slag coarse aggregate to the coating slurry is 1g: 2.5-4ml. Optionally, the particle size of the steel slag coarse aggregate is 10-20mm.

[0014] Furthermore, in step (2), the shell powder can completely cover the coating slurry on the surface of the coarse aggregate.

[0015] Furthermore, in step (2), the sintering treatment time is 20 to 30 minutes.

[0016] Furthermore, in step (3), the ratio of the pre-modified steel slag coarse aggregate to the acid solution is 1g:10-20ml. Optionally, the acid solution comprises at least one of hydrochloric acid, nitric acid, acetic acid, etc. The concentration of the acid solution is 3-6 mol / L.

[0017] Furthermore, in step (3), the soaking time is 50 to 70 minutes. Optionally, clean water is used for the washing to remove the acid remaining in the aggregate.

[0018] Furthermore, in step (3), the ratio of the coarse aggregate to the alkaline suspension is 1g:5~20ml. - The concentration of OH is 0.2~0.4mol / L. - It can be provided by at least one of sodium hydroxide, potassium hydroxide, etc.

[0019] Furthermore, in step (3), the amount of graphene oxide added to the alkaline suspension is 7-12 g / L.

[0020] Furthermore, in step (3), the heating and heat preservation temperature is 40-60° C., and the time is 3-5 hours.

[0021] Furthermore, in step (4), the proportions of the components in the raw materials are: 800-1000 parts by weight of Portland cement, 1700-2200 parts by weight of modified steel slag coarse aggregate, 1250-1400 parts by weight of river sand fine aggregate, 200-310 parts by weight of fly ash, 130-180 parts by weight of mineral powder, 60-90 parts by weight of flexible fiber filaments, and 12-20 parts by weight of water reducer. The water is added according to a water-cement ratio of 0.22-0.3, that is, the mass ratio of the water to Portland cement is 0.22-0.3:1.

[0022] Furthermore, in step (4), the flexible fiber filaments include at least one of polyethylene fiber filaments, polypropylene fiber filaments, polyvinyl alcohol fiber filaments, and basalt fiber filaments. Optionally, the flexible fiber filaments have a length of 10 to 30 mm and a diameter of 0.2 to 0.5 mm. After being distributed in the pavement brick matrix, the flexible fiber filaments further help to form entanglements with the basalt fibers on the surface of the steel slag aggregate. After forming a bond under the bonding of the cementitious product formed by the hydration of the cement, the flexible fiber filaments help to further improve the bonding strength between the steel slag aggregate and the pavement brick matrix.

[0023] Furthermore, in step (4), the water reducer includes at least one of a polycarboxylic acid water reducer, a naphthalene-based water reducer, a lignin sulfonate water reducer, and the like.

[0024] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0025] The present invention first coats the surface of steel slag coarse aggregate with a slurry composed of glass powder, shell powder, chopped basalt fibers, and sodium silicate, then coats it again with shell powder and sintering it. As a result, the glass powder is first melted and then cooled and hardened, fixing the chopped basalt fibers to the surface of the steel slag coarse aggregate. At the same time, the glass particles adhering to the surface of the basalt fibers are doped with shell powder particles. When the steel slag coarse aggregate is placed in an acid solution, the shell powder or its calcined product gradually dissolves, exposing the basalt fibers to the outer surface of the steel slag coarse aggregate. Simultaneously, the shell powder particles doped with the glass particles on the surface of the basalt fibers are removed, resulting in a rougher fiber surface. Furthermore, during this process, the acid enters the steel slag coarse aggregate and reacts with the free calcium oxide therein, eliminating the problem of poor volume stability and preventing the prepared pavement bricks from developing internal cracks and fissures during use, which can lead to a decrease in mechanical strength and shortened service life.

[0026] Furthermore, the present invention adds the above-mentioned steel slag coarse aggregate into the alkaline suspension of graphene oxide for treatment. During this process, the silicon-oxygen tetrahedrons on the surface of the basalt fiber on the aggregate are OH-ionized in the alkaline solution. - Under the action of the above-mentioned process, the coarsened basalt fibers gradually depolymerize to form -Si(OH)3 and other groups. These further condense with the hydroxyl groups (-OH) on the surface of the graphene oxide to form silyl-ether bonds, thereby loading graphene oxide on the surface of the basalt fibers. Similarly, the -Si(OH)3 and other groups formed after the depolymerization of silicon-oxygen tetrahedron structures on the surface of the steel slag in an alkaline environment can also load graphene oxide on the surface of the steel slag. When using the steel slag coarse aggregate improved by the above process to prepare cement-based unburned pavement bricks, the coarsened basalt fibers on the surface of the steel slag coarse aggregate are anchored in the pavement brick matrix. Furthermore, after being stimulated by alkaline solution, the basalt fibers can react with calcium hydroxide, a cement hydration product, to form a hydrated calcium silicate cementitious component. These two effects not only significantly increase the bonding strength between the steel slag coarse aggregate and the pavement brick matrix, improving the mechanical strength of the pavement bricks, but also effectively reduce the problem of the aggregate easily peeling off and separating from the pavement brick matrix due to external forces such as friction during use, thereby increasing the service life of the pavement bricks. In addition, the graphene on the surface of the steel slag coarse aggregate and the basalt fiber is also beneficial to strengthening the weak interface area and improving the bonding force between the steel slag coarse aggregate and the pavement brick matrix. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute undue limitations thereon. The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0028] Figure 1 This is a sample of cement-based unfired pavement bricks prepared in Example 1 below.

[0029] Figure 2 This is a sample of cement-based unfired pavement bricks prepared in the following Example 2.

[0030] Figure 3 This is a sample of cement-based unfired pavement bricks prepared in Example 3 below.

[0031] Figure 4 This is a sample of cement-based unfired pavement bricks prepared in the following Example 4.

[0032] Figure 5 This is a sample of cement-based unfired pavement bricks prepared in the following Example 5.

[0033] Figure 6 This is a sample of cement-based unfired pavement bricks prepared in the following Example 6.

[0034] Figure 7 This is a sample of cement-based unfired pavement bricks prepared in the following Example 7.

[0035] Figure 8 This is a sample of cement-based unfired pavement bricks prepared in the following Example 8.

[0036] Figure 9 This is a sample of cement-based unfired pavement bricks prepared in the following Example 9. DETAILED DESCRIPTION

[0037] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present invention only and are not intended to limit the scope of the invention. The experimental methods in the following examples, for which specific conditions are not specified, are generally performed under conventional conditions or as recommended by the manufacturer.

[0038] Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. The reagents and raw materials used in the present invention can be purchased through conventional channels. Unless otherwise specified, the reagents and raw materials used in the present invention are used in a conventional manner in the art or according to the product instructions. In addition, any methods and materials similar to or equivalent to those described herein can be applied to the present invention.

[0039] Example 1:

[0040] A preparation process for high-strength cement-based unburned paving bricks comprises the following steps:

[0041] (1) Take 400-mesh waste glass powder (softening temperature between 720 and 740°C), shell powder, chopped basalt fiber (length 7 mm, diameter 0.4 mm), and sodium silicate. Mix the glass powder, shell powder, chopped basalt fiber, and sodium silicate in a mass ratio of 3:2:1.5:0.8 and stir evenly. Then add clean water and stir evenly to obtain a coating slurry with a solid content of 45 wt.% and set aside.

[0042] (2) Add the coating slurry to steel slag coarse aggregate with a particle size distribution between 10 and 15 mm in a ratio of 1 g:3.5 ml. After the two are evenly mixed, separate the coarse aggregate and then place it in shell powder for coating again, so that the shell powder completely covers the coating slurry on the surface of the coarse aggregate. Then, heat the coated steel slag coarse aggregate to 790°C and keep it warm for 20 minutes. After completion, cool it to room temperature to obtain pre-modified steel slag coarse aggregate for later use.

[0043] (3) The pre-modified steel slag coarse aggregate was mixed with 4 mol / L hydrochloric acid in a ratio of 1 g: 15 ml, stirred evenly, and then soaked for 60 minutes. After completion, the coarse aggregate was separated by filtration. Washed twice with clean water, and then added to the sodium hydroxide solution in which graphene oxide was dispersed, with the ratio of the two being 1 g: 12 ml. - The concentration of 0.3 mol / L and the content of graphene oxide are 10 g / L. The obtained mixture is then heated to 50° C. and kept warm for 4 hours. After the mixture is heated, the coarse aggregate is separated to obtain the modified steel slag coarse aggregate for later use.

[0044] (4) Take 870 parts by weight of 42.4 ordinary Portland cement, 1820 parts by weight of the modified steel slag coarse aggregate of this embodiment, 1300 parts by weight of river sand fine aggregate with a particle size distribution between 0.5 and 2 mm, 250 parts by weight of fly ash, 145 parts by weight of mineral powder, 72 parts by weight of polyvinyl alcohol fiber (length 20 mm, diameter 0.3 mm), and 16 parts by weight of polycarboxylic acid water reducer. Mix the above components and stir for 2 minutes, then add clean water according to a water-cement ratio of 0.26 and stir evenly. Pour the obtained slurry into a mold and press it into shape (pressure of 20 MPa, time of 30 seconds). After hardening, demould it and then naturally cure it until the 28th day to obtain cement-based unburned pavement bricks. Figure 1 shown.

[0045] Performance test: According to the "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete" (GB / T50082-2009), the compressive strength of the cement-based unburned pavement brick prepared in this embodiment was tested, and the result was 60.38 MPa.

[0046] Example 2:

[0047] A preparation process for high-strength cement-based unburned paving bricks comprises the following steps:

[0048] (1) Take 300-mesh waste glass powder (softening temperature between 720 and 740°C), shell powder, chopped basalt fiber (length 10 mm, diameter 0.5 mm), and sodium silicate. Mix the glass powder, shell powder, chopped basalt fiber, and sodium silicate in a mass ratio of 2.8:2:1.2:0.7 and stir evenly. Then, add clean water and stir evenly to obtain a coating slurry with a solid content of 40 wt.% and set aside.

[0049] (2) Add the coating slurry to steel slag coarse aggregate with a particle size distribution between 10 and 20 mm in a ratio of 1 g:2.5 ml. After the two are evenly mixed, separate the coarse aggregate and then place it in shell powder for coating again, so that the shell powder completely covers the coating slurry on the surface of the coarse aggregate. Then, heat the coated steel slag coarse aggregate to 770°C and keep it warm for 30 minutes. After completion, cool it to room temperature to obtain pre-modified steel slag coarse aggregate for later use.

[0050] (3) The pre-modified steel slag coarse aggregate was mixed with 3 mol / L nitric acid in a ratio of 1 g: 10 ml and stirred evenly, and then soaked for 50 minutes. After completion, the coarse aggregate was separated by filtration. It was washed twice with clean water and then added to the sodium hydroxide solution in which graphene oxide was dispersed, with the ratio of the two being 1 g: 20 ml. - The concentration of 0.2 mol / L and the content of graphene oxide are 7 g / L. The obtained mixture is then heated to 60° C. and kept warm for 3 hours. After the mixture is heated, the coarse aggregate is separated to obtain the modified steel slag coarse aggregate for later use.

[0051] (4) Take 1000 parts by weight of 42.4 ordinary Portland cement, 2200 parts by weight of the modified steel slag coarse aggregate of this embodiment, 1400 parts by weight of river sand fine aggregate with a particle size distribution between 0.5 and 2 mm, 310 parts by weight of fly ash, 180 parts by weight of mineral powder, 90 parts by weight of polypropylene fiber (length 10 mm, diameter 0.2 mm), and 20 parts by weight of sodium lignin sulfonate water reducer. Mix the above components and stir for 2 minutes, then add clean water according to a water-cement ratio of 0.3 and stir evenly. Pour the obtained slurry into a mold and press it into shape (pressure of 20 MPa, time of 30 seconds). After hardening, demould it and then naturally cure it until the 28th day to obtain cement-based unburned pavement bricks. Figure 2 shown.

[0052] Performance test: According to the "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete" (GB / T50082-2009), the compressive strength of the cement-based unburned pavement brick prepared in this embodiment was tested, and the result was 57.03 MPa.

[0053] Example 3:

[0054] A preparation process for high-strength cement-based unburned paving bricks comprises the following steps:

[0055] (1) Take 300-mesh waste glass powder (softening temperature between 720 and 740°C), shell powder, chopped basalt fiber (length 5 mm, diameter 0.2 mm), and sodium silicate. Mix the glass powder, shell powder, chopped basalt fiber, and sodium silicate in a mass ratio of 3.5:2:1.8:0.9 and stir evenly. Then add clean water and stir evenly to obtain a coating slurry with a solid content of 50 wt.% for later use.

[0056] (2) Add the coating slurry to steel slag coarse aggregate with a particle size distribution between 10 and 20 mm in a ratio of 1 g:4 ml. After the two are evenly mixed, separate the coarse aggregate and then place it in shell powder for coating again, so that the shell powder completely covers the coating slurry on the surface of the coarse aggregate. Then heat the coated steel slag coarse aggregate to 780°C and keep it warm for 25 minutes. After completion, cool it to room temperature to obtain pre-modified steel slag coarse aggregate for later use.

[0057] (3) The pre-modified steel slag coarse aggregate was mixed with 6 mol / L acetic acid in a ratio of 1 g: 20 ml and stirred evenly, and then soaked for 70 minutes. After completion, the coarse aggregate was separated by filtration. It was washed twice with clean water and then added to a potassium hydroxide solution in which graphene oxide was dispersed, with a ratio of 1 g: 5 ml. - The concentration of 0.4 mol / L and the content of graphene oxide are 12 g / L. The obtained mixture is then heated to 40° C. and kept warm for 5 hours. After the mixture is heated, the coarse aggregate is separated to obtain the modified steel slag coarse aggregate for later use.

[0058] (4) Take 800 parts by weight of 42.4 ordinary Portland cement, 1700 parts by weight of the modified steel slag coarse aggregate of this embodiment, 1250 parts by weight of river sand fine aggregate with a particle size distribution between 0.5 and 2 mm, 200 parts by weight of fly ash, 130 parts by weight of mineral powder, 60 parts by weight of basalt fiber (length 30 mm, diameter 0.5 mm), and 12 parts by weight of polycarboxylate water reducer. Mix the above components and stir for 2 minutes, then add clean water according to a water-cement ratio of 0.22 and stir evenly. Pour the obtained slurry into a mold and press it into shape (pressure of 18 MPa, time of 30 seconds). After hardening, demould it and then naturally cure it until the 28th day to obtain cement-based unburned pavement bricks. Figure 3 shown.

[0059] Performance test: According to the "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete" (GB / T50082-2009), the compressive strength of the cement-based unburned pavement brick prepared in this embodiment was tested, and the result was 61.79 MPa.

[0060] Example 4:

[0061] A preparation process for high-strength cement-based unburned paving bricks comprises the following steps:

[0062] Take 870 parts by weight of 42.4 ordinary Portland cement, 1820 parts by weight of steel slag coarse aggregate with a particle size distribution between 10 and 15 mm, 1300 parts by weight of river sand fine aggregate with a particle size distribution between 0.5 and 2 mm, 250 parts by weight of fly ash, 145 parts by weight of mineral powder, 72 parts by weight of polyvinyl alcohol fiber (length 20 mm, diameter 0.3 mm), and 16 parts by weight of polycarboxylic acid water reducer. Mix the above components and stir for 2 minutes, then add clean water according to a water-cement ratio of 0.26 and stir evenly. Pour the obtained slurry into a mold and press it into shape (pressure of 20 MPa, time of 30 seconds). After hardening, demould it and then naturally cure it until the 28th day to obtain cement-based unburned pavement bricks. Figure 4 shown.

[0063] Performance test: According to the "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete" (GB / T50082-2009), the compressive strength of the cement-based unburned pavement brick prepared in this embodiment was tested, and the result was 33.26 MPa.

[0064] Example 5:

[0065] A preparation process for high-strength cement-based unburned paving bricks comprises the following steps:

[0066] (1) Mix steel slag coarse aggregate with a particle size distribution between 10 and 20 mm with 3 mol / L nitric acid at a ratio of 1 g: 10 ml, stir evenly, and then soak for 50 minutes. After completion, filter and separate the coarse aggregate. Wash it twice with clean water, and then add it to a sodium hydroxide solution with graphene oxide dispersed in it at a ratio of 1 g: 20 ml. - The concentration of 0.2 mol / L and the content of graphene oxide are 7 g / L. The obtained mixture is then heated to 60° C. and kept warm for 3 hours. After the mixture is heated, the coarse aggregate is separated to obtain the modified steel slag coarse aggregate for later use.

[0067] (2) Take 1000 parts by weight of 42.4 ordinary Portland cement, 2200 parts by weight of the modified steel slag coarse aggregate of this embodiment, 1400 parts by weight of river sand fine aggregate with a particle size distribution between 0.5 and 2 mm, 310 parts by weight of fly ash, 180 parts by weight of mineral powder, 90 parts by weight of polypropylene fiber (length 10 mm, diameter 0.2 mm), and 20 parts by weight of sodium lignin sulfonate water reducer. Mix the above components and stir for 2 minutes, then add clean water according to a water-cement ratio of 0.3 and stir evenly. Pour the obtained slurry into a mold and press it into shape (pressure of 20 MPa, time of 30 seconds). After hardening, demould it and then naturally cure it until the 28th day to obtain cement-based unburned pavement bricks. Figure 5 shown.

[0068] Performance test: According to the "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete" (GB / T50082-2009), the compressive strength of the cement-based unburned pavement brick prepared in this embodiment was tested, and the result was 45.27 MPa.

[0069] Example 6:

[0070] A preparation process for high-strength cement-based unburned paving bricks comprises the following steps:

[0071] (1) Pre-modified steel slag coarse aggregate (prepared as in Example 1 above) was mixed with 4 mol / L hydrochloric acid at a ratio of 1 g:15 ml, stirred evenly, and then soaked for 60 minutes. After completion, the coarse aggregate was separated by filtration. The coarse aggregate was washed twice with clean water and then added to clean water in which graphene oxide was dispersed at a ratio of 1 g:12 ml. The graphene oxide content in the clean water was 10 g / L. The resulting mixture was then heated to 50°C and kept warm for 4 hours. After completion, the coarse aggregate was separated to obtain modified steel slag coarse aggregate for later use.

[0072] (2) Take 870 parts by weight of 42.4 ordinary Portland cement, 1820 parts by weight of the modified steel slag coarse aggregate of this embodiment, 1300 parts by weight of river sand fine aggregate with a particle size distribution between 0.5 and 2 mm, 250 parts by weight of fly ash, 145 parts by weight of mineral powder, 72 parts by weight of polyvinyl alcohol fiber (length 20 mm, diameter 0.3 mm), and 16 parts by weight of polycarboxylic acid water reducer. Mix the above components and stir for 2 minutes, then add clean water according to a water-cement ratio of 0.26 and stir evenly. Pour the obtained slurry into a mold and press it into shape (pressure of 20 MPa, time of 30 seconds). After hardening, demould it and then naturally cure it until the 28th day to obtain cement-based unburned pavement bricks. Figure 6 shown.

[0073] Performance test: According to the "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete" (GB / T50082-2009), the compressive strength of the cement-based unburned pavement brick prepared in this embodiment was tested, and the result was 56.18 MPa.

[0074] Example 7:

[0075] A preparation process for high-strength cement-based unburned paving bricks comprises the following steps:

[0076] (1) Take 300-mesh shell powder, chopped basalt fibers (5 mm in length, 0.2 mm in diameter), and sodium silicate. Mix the shell powder, chopped basalt fibers, and sodium silicate in a mass ratio of 2:1.8:0.9 and stir evenly. Then, add clean water and stir evenly to obtain a coating slurry with a solid content of 50 wt.%, which is set aside.

[0077] (2) Add the coating slurry to steel slag coarse aggregate with a particle size distribution between 10 and 20 mm in a ratio of 1 g:4 ml. After the two are evenly mixed, separate the coarse aggregate and then place it in shell powder for coating again, so that the shell powder completely covers the coating slurry on the surface of the coarse aggregate. Then heat the coated steel slag coarse aggregate to 780°C and keep it warm for 25 minutes. After completion, cool it to room temperature to obtain pre-modified steel slag coarse aggregate for later use.

[0078] (3) The pre-modified steel slag coarse aggregate was mixed with 6 mol / L acetic acid in a ratio of 1 g: 20 ml and stirred evenly, and then soaked for 70 minutes. After completion, the coarse aggregate was separated by filtration. It was washed twice with clean water and then added to a potassium hydroxide solution in which graphene oxide was dispersed, with a ratio of 1 g: 5 ml. - The concentration of 0.4 mol / L and the content of graphene oxide are 12 g / L. The obtained mixture is then heated to 40° C. and kept warm for 5 hours. After the mixture is heated, the coarse aggregate is separated to obtain the modified steel slag coarse aggregate for later use.

[0079] (4) Take 800 parts by weight of 42.4 ordinary Portland cement, 1700 parts by weight of the modified steel slag coarse aggregate of this embodiment, 1250 parts by weight of river sand fine aggregate with a particle size distribution between 0.5 and 2 mm, 200 parts by weight of fly ash, 130 parts by weight of mineral powder, 60 parts by weight of basalt fiber (length 30 mm, diameter 0.5 mm), and 12 parts by weight of polycarboxylate water reducer. Mix the above components and stir for 2 minutes, then add clean water according to a water-cement ratio of 0.22 and stir evenly. Pour the obtained slurry into a mold and press it into shape (pressure of 18 MPa, time of 30 seconds). After hardening, demould it and then naturally cure it until the 28th day to obtain cement-based unburned pavement bricks. Figure 7 shown.

[0080] Performance test: According to the "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete" (GB / T50082-2009), the compressive strength of the cement-based unburned pavement brick prepared in this embodiment was tested, and the result was 50.66 MPa.

[0081] Example 8:

[0082] A preparation process for high-strength cement-based unburned paving bricks comprises the following steps:

[0083] (1) Take 300-mesh waste glass powder (softening temperature between 720 and 740°C), chopped basalt fiber (length 10 mm, diameter 0.5 mm), and sodium silicate. Mix the glass powder, chopped basalt fiber, and sodium silicate in a mass ratio of 2.8:1.2:0.7 and stir evenly. Then, add clean water and stir evenly to obtain a coating slurry with a solid content of 40 wt.% for later use.

[0084] (2) Add the coating slurry to steel slag coarse aggregate with a particle size distribution between 10 and 20 mm in a ratio of 1 g:2.5 ml. After the two are evenly mixed, separate the coarse aggregate and then place it in shell powder for coating again, so that the shell powder completely covers the coating slurry on the surface of the coarse aggregate. Then, heat the coated steel slag coarse aggregate to 770°C and keep it warm for 30 minutes. After completion, cool it to room temperature to obtain pre-modified steel slag coarse aggregate for later use.

[0085] (3) The pre-modified steel slag coarse aggregate was mixed with 3 mol / L nitric acid in a ratio of 1 g: 10 ml and stirred evenly, and then soaked for 50 minutes. After completion, the coarse aggregate was separated by filtration. It was washed twice with clean water and then added to the sodium hydroxide solution in which graphene oxide was dispersed, with the ratio of the two being 1 g: 20 ml. - The concentration of 0.2 mol / L and the content of graphene oxide are 7 g / L. The obtained mixture is then heated to 60° C. and kept warm for 3 hours. After the mixture is heated, the coarse aggregate is separated to obtain the modified steel slag coarse aggregate for later use.

[0086] (4) Take 1000 parts by weight of 42.4 ordinary Portland cement, 2200 parts by weight of the modified steel slag coarse aggregate of this embodiment, 1400 parts by weight of river sand fine aggregate with a particle size distribution between 0.5 and 2 mm, 310 parts by weight of fly ash, 180 parts by weight of mineral powder, 90 parts by weight of polypropylene fiber (length 10 mm, diameter 0.2 mm), and 20 parts by weight of sodium lignin sulfonate water reducer. Mix the above components and stir for 2 minutes, then add clean water according to a water-cement ratio of 0.3 and stir evenly. Pour the obtained slurry into a mold and press it into shape (pressure of 20 MPa, time of 30 seconds). After hardening, demould it and then naturally cure it until the 28th day to obtain cement-based unburned pavement bricks. Figure 8 shown.

[0087] Performance test: According to the "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete" (GB / T50082-2009), the compressive strength of the cement-based unburned pavement brick prepared in this embodiment was tested, and the result was 48.45 MPa.

[0088] Example 9:

[0089] A preparation process for high-strength cement-based unburned paving bricks comprises the following steps:

[0090] Take 800 parts by weight of 42.4 ordinary Portland cement, 1700 parts by weight of modified steel slag coarse aggregate (prepared in the same way as in Example 3 above), 1250 parts by weight of river sand fine aggregate with a particle size distribution between 0.5 and 2 mm, 200 parts by weight of fly ash, 130 parts by weight of mineral powder, and 12 parts by weight of polycarboxylate water reducer. Mix the above components and stir for 2 minutes. Then, add clean water at a water-cement ratio of 0.22 and stir evenly. Pour the resulting slurry into a mold and press it into shape (at a pressure of 18 MPa for 30 seconds). After hardening, demould it and then naturally cure it for 28 days to obtain cement-based unburned paving bricks. Figure 9 shown.

[0091] Performance test: According to the "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete" (GB / T50082-2009), the compressive strength of the cement-based unburned pavement brick prepared in this embodiment was tested, and the result was 54.31 MPa.

[0092] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to repair the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any repairs, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A process for preparing high-strength cement-based unburned paving bricks, characterized in that: The steps include: (1) Mix glass powder, shell powder, chopped basalt fiber, sodium silicate and water and stir them evenly to form a coating slurry for later use; the mass ratio of the glass powder, shell powder, chopped basalt fiber and sodium silicate is 2.8-3.5:2:1.2-1.8:0.7-0.9; (2) adding the coating slurry to the steel slag coarse aggregate, mixing the obtained coarse aggregate evenly, placing the obtained coarse aggregate in shell powder for coating again, and then sintering the obtained coated steel slag coarse aggregate at a temperature higher than the softening temperature of the glass powder. After completion, cooling is performed to obtain pre-modified steel slag coarse aggregate for standby use; (3) Soaking the pre-modified steel slag coarse aggregate in an acid solution, separating the coarse aggregate after completion, washing it, adding it to an alkaline suspension of graphene oxide, and heating and keeping it warm; after the reaction is completed, the modified steel slag coarse aggregate is obtained and set aside; (4) Take 800-1000 parts by weight of Portland cement, 1700-2200 parts by weight of the modified steel slag coarse aggregate, 1250-1400 parts by weight of river sand fine aggregate, 200-310 parts by weight of fly ash, 130-180 parts by weight of mineral powder, 60-90 parts by weight of flexible fiber yarn, and 12-20 parts by weight of water reducer as raw materials, mix the raw materials evenly, add water according to a water-cement ratio of 0.22-0.3, and pour the obtained slurry into a mold for pressing and forming. After demoulding, curing is carried out to obtain cement-based unburned pavement bricks.

2. The preparation process of high-strength cement-based unburned paving brick according to claim 1, characterized in that: In step (1), water is added according to the solid content of the coating slurry being 40-50 wt.%.

3. The preparation process of high-strength cement-based unburned paving brick according to claim 1, characterized in that: In step (1), the length of the chopped basalt fiber is 5-10 mm, and the diameter is 0.2-0.5 mm.

4. The process for preparing high-strength cement-based unburned paving bricks according to claim 1, characterized in that: In step (1), the fineness of the glass powder and shell powder is 300-400 mesh.

5. The preparation process of high-strength cement-based unburned paving brick according to claim 1, characterized in that: In step (2), the ratio of the steel slag coarse aggregate to the coating slurry is 1g:2.5~4ml.

6. The process for preparing high-strength cement-based unburned paving bricks according to claim 1, characterized in that: In step (2), the particle size of the steel slag coarse aggregate is 10-20 mm.

7. The process for preparing high-strength cement-based unburned paving bricks according to claim 1, characterized in that: In step (2), the shell powder can completely cover the coating slurry on the surface of the coarse aggregate.

8. The process for preparing high-strength cement-based unburned paving bricks according to claim 1, characterized in that: In step (2), the sintering treatment time is 20 to 30 minutes.

9. The process for preparing high-strength cement-based unburned paving bricks according to claim 1, characterized in that: In step (3), the ratio of the pre-modified steel slag coarse aggregate to the acid solution is 1g:10~20ml.

10. The process for preparing high-strength cement-based unburned paving bricks according to claim 1, characterized in that: In step (3), the acid solution includes at least one of hydrochloric acid, nitric acid, and acetic acid.

11. The process for preparing high-strength cement-based unburned paving bricks according to claim 1, characterized in that: In step (3), the concentration of the acid solution is 3-6 mol / L.

12. The process for preparing high-strength cement-based unburned paving bricks according to claim 1, characterized in that: In step (3), the soaking time is 50 to 70 minutes.

13. The process for preparing high-strength cement-based unburned paving bricks according to claim 1, characterized in that: In step (3), clean water is used to wash and remove the acid remaining in the aggregate.

14. The process for preparing high-strength cement-based unburned paving bricks according to claim 1, characterized in that: In step (3), the ratio of the coarse aggregate to the alkaline suspension is 1 g: 5-20 ml.

15. The process for preparing high-strength cement-based unburned paving bricks according to claim 1, wherein: In step (3), the OH in the alkaline suspension - The concentration is 0.2~0.4mol / L.

16. The process for preparing high-strength cement-based unburned pavement bricks according to claim 15, characterized in that: The OH - Provided by at least one of sodium hydroxide and potassium hydroxide.

17. The process for preparing high-strength cement-based unburned pavement bricks according to claim 1, characterized in that: In step (3), the amount of graphene oxide added to the alkaline suspension is 7-12 g / L; the heating and insulation temperature is 40-60° C., and the time is 3-5 hours.

18. The process for preparing high-strength cement-based unburned paving bricks according to any one of claims 1 to 17, characterized in that: In step (4), the flexible fiber filaments include at least one of polyethylene fiber filaments, polypropylene fiber filaments, polyvinyl alcohol fiber filaments, and basalt fiber filaments.

19. The process for preparing high-strength cement-based unburned paving bricks according to any one of claims 1 to 17, characterized in that: In step (4), the length of the flexible fiber filament is 10-30 mm, and the diameter is 0.2-0.5 mm.

20. The process for preparing high-strength cement-based unburned pavement bricks according to any one of claims 1 to 17, characterized in that: In step (4), the water reducer includes at least one of a polycarboxylic acid water reducer, a naphthalene water reducer, and a lignin sulfonate water reducer.

Images