Preparation process of high-strength cement-based baking-free pavement brick

Abstract

The invention relates to the technical field of preparation of pavement bricks, and particularly discloses a preparation process of a high-strength cement-based baking-free pavement brick, which comprises the following steps: (1) uniformly mixing glass powder, shell powder, basalt fiber, sodium silicate and water to form coating slurry; and (2) adding the coating slurry into the steel slag coarse aggregate, uniformly mixing to obtain the coarse aggregate, coating the coarse aggregate in shell powder again, and sintering to obtain the pre-modified steel slag coarse aggregate. And (3) soaking the pre-modified steel slag coarse aggregate in an acid solution, separating out the coarse aggregate after soaking, cleaning, adding the coarse aggregate into an alkaline suspension of graphene oxide, and heating and preserving heat to obtain the improved steel slag coarse aggregate. And (4) preparing the cement-based baking-free pavement brick by taking Portland cement, the improved steel slag coarse aggregate, the river sand fine aggregate and the like as raw materials. The binding force between the steel slag aggregate prepared by the process and the baking-free pavement brick matrix is better, the problem of poor volume stability of the steel slag aggregate is eliminated, the strength of the baking-free pavement brick is improved, and the service life of the baking-free pavement brick is prolonged.

Description

Technical Field

[0001] The 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 the 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 a person skilled in the art.

[0003] Cement-based unburned bricks are made by mixing industrial waste residues, construction waste and other raw materials with cement binder materials and then undergoing molding and curing processes. They do not need to be fired at high temperatures in a kiln like traditional fired bricks, so they are called "unburned" bricks. The production of unburned bricks not only helps to recycle industrial solid waste, but also reduces energy consumption and carbon emissions. It is a greener, more environmentally friendly and low-carbon product than fired bricks. At present, cement-based unburned bricks have been widely used in the paving of various roads, such as sidewalks, driveways, squares, parking lots, etc.

[0004] Steel slag is a kind of waste residue produced in the steelmaking process. It is not only strong but also wear-resistant. my country's steel production ranks among the top in the world, which also brings a large amount of steel slag. Using steel slag as aggregate and using it in the preparation of cement-based unburned bricks is a feasible way to utilize solid waste. However, since steel slag contains free calcium oxide and magnesium oxide, it will expand in volume after reacting with water, which can easily form internal stress in unburned bricks. When this internal stress exceeds the strength of unburned bricks, cracks will occur, which will lead to the deterioration of the strength of unburned bricks. In addition, due to the low reactivity of steel slag, its bonding strength with the unburned brick matrix is ​​insufficient. During service, the steel slag particles on the surface of the unburned 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 unburned bricks. Summary of the invention

[0005] In view of the above problems, the present invention discloses a process for preparing high-strength cement-based unfired pavement bricks, wherein the steel slag aggregate prepared by the process has better bonding strength with the brick matrix, and eliminates the problem of poor volume stability existing in the process, thereby improving the strength and service life of unfired pavement bricks. Specifically, the technical solution of the present invention is as follows.

[0006] A preparation process of high-strength cement-based unburned pavement bricks, comprising the following steps: (1) Mix glass powder, shell powder, chopped basalt fiber, sodium silicate and water and stir evenly to form a coating slurry for later use.

[0007] (2) Add the coating slurry to the steel slag coarse aggregate, mix well, place the obtained coarse aggregate in shell powder for coating again, and then sinter the obtained coated steel slag coarse aggregate at a temperature higher than the softening temperature of the glass powder. After completion, cool it to obtain pre-modified steel slag coarse aggregate for standby use.

[0008] (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.

[0009] (4) Taking silicate cement, the modified steel slag coarse aggregate, river sand fine aggregate, fly ash, mineral powder, flexible fiber filaments and water reducing agent as raw materials, mixing the raw materials evenly and adding water to mix evenly, pouring the obtained slurry into a mold for pressing and forming, and curing after demolding to obtain cement-based unburned pavement bricks.

[0010] 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 length of the chopped basalt fiber is 5-10 mm, and the diameter is 0.2-0.5 mm. The fineness of the glass powder and shell powder is 300-400 mesh.

[0011] Furthermore, in step (1), water is added according to the solid content of the coating slurry being 40-50 wt.%.

[0012] Furthermore, in step (2), the ratio of the steel slag coarse aggregate to the coating slurry is 1 g: 2.5-4 ml. Optionally, the particle size of the steel slag coarse aggregate is 10-20 mm.

[0013] Furthermore, in step (2), the shell powder can completely cover the coating slurry on the surface of the coarse aggregate.

[0014] Furthermore, in step (2), the sintering treatment time is 20 to 30 minutes.

[0015] Furthermore, in step (3), the ratio of the pre-modified steel slag coarse aggregate to the acid solution is 1 g: 10-20 ml. Optionally, the acid solution includes at least one of hydrochloric acid, nitric acid, acetic acid, etc. The concentration of the acid solution is 3-6 mol / L.

[0016] Furthermore, in step (3), the soaking time is 50 to 70 minutes. Optionally, clean water is used for the washing to remove the acid solution remaining in the aggregate.

[0017] 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.

[0018] Furthermore, in step (3), the amount of graphene oxide added to the alkaline suspension is 7-12 g / L.

[0019] Furthermore, in step (3), the heating and heat preservation temperature is 40-60° C. and the time is 3-5 hours.

[0020] Furthermore, in step (4), the proportions of the components in the raw materials are: 800-1000 parts by weight of silicate 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 at a water-cement ratio of 0.22-0.3, that is, the mass ratio of water to silicate cement is 0.22-0.3:1.

[0021] Furthermore, in step (4), the flexible fiber filaments include at least one of polyethylene fiber filaments, polypropylene fiber filaments, polyvinyl alcohol fiber filaments, basalt fiber filaments, etc. Optionally, the length of the flexible fiber filaments is 10-30 mm, and the diameter is 0.2-0.5 mm. After the flexible fiber filaments are distributed in the pavement brick matrix, they also help to form entanglements with the basalt fibers on the surface of the steel slag aggregate. After the flexible fiber filaments form a combination under the bonding of the cementitious product formed by the hydration of the cement, they help to further improve the bonding force between the steel slag aggregate and the pavement brick matrix.

[0022] 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.

[0023] Compared with the prior art, the present invention has at least the following beneficial technical effects: The present invention first coats the surface of steel slag coarse aggregate with a slurry formed by glass powder, shell powder, chopped basalt fiber, and sodium silicate, and then coats it again with shell powder and performs sintering treatment, so that the chopped basalt fiber is fixed on the surface of the steel slag coarse aggregate by first melting the glass powder and then cooling and hardening, and at the same time, the glass particles adhered to the surface of the basalt fiber are doped with shell powder particles. When the above-mentioned steel slag coarse aggregate is placed in acid solution, the shell powder or its calcined product gradually dissolves, thereby exposing the basalt fiber on the outer surface of the steel slag coarse aggregate. At the same time, after the shell powder particles doped in the glass particles on the surface of the basalt fiber are removed, a rougher fiber surface is formed. In addition, in 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 caused by it, and preventing the prepared pavement bricks from having a decrease in mechanical strength and a shortened service life due to internal cracks and cracking during use.

[0024] Furthermore, the present invention adds the above-mentioned steel slag coarse aggregate to an 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 process, it gradually depolymerizes to form -Si(OH)3 and the like. It further reacts with the hydroxyl (-OH) on the surface of the graphene oxide to form a silyl ether bond, thereby loading graphene oxide on the surface of the basalt fiber. Similarly, the -Si(OH)3 and the like formed after the silicon-oxygen tetrahedron and other structures on the surface of the steel slag depolymerize in an alkaline environment can also load graphene oxide on the surface of the steel slag. When the steel slag coarse aggregate improved by the above process is used 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, and the basalt fibers after being excited by alkali can also react with the cement hydration product calcium hydroxide to form a hydrated calcium silicate gelling component. The above two effects can not only significantly increase the bonding force between the steel slag coarse aggregate and the pavement brick matrix, and improve the mechanical strength of the pavement brick, but also effectively reduce the problem of the aggregate being easily peeled off and separated from the pavement brick matrix under the action of external forces such as friction during use, thereby increasing the service life of the pavement brick. 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

[0025] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. The embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein: Figure 1 This is a sample picture of cement-based unfired pavement bricks prepared in the following Example 1.

[0026] Figure 2 This is a sample picture of cement-based unfired pavement bricks prepared in the following Example 2.

[0027] Figure 3 This is a sample picture of cement-based unfired pavement bricks prepared in the following Example 3.

[0028] Figure 4 This is a sample picture of cement-based unfired pavement bricks prepared in the following Example 4.

[0029] Figure 5 This is a sample of cement-based unfired pavement bricks prepared in the following Example 5.

[0030] Figure 6 This is a sample picture of cement-based unfired pavement bricks prepared in the following Example 6.

[0031] Figure 7 This is a sample picture of cement-based unfired pavement bricks prepared in the following Example 7.

[0032] Figure 8 This is a sample picture of cement-based unfired pavement bricks prepared in the following Example 8.

[0033] Fig. 9 This is a sample of cement-based unfired pavement bricks prepared in the following Example 9. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer.

[0035] 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 or raw materials used in the present invention can be purchased through conventional channels. Unless otherwise specified, the reagents or raw materials used in the present invention are used in a conventional manner in the art or in accordance with the product instructions. In addition, any method and material similar or equivalent to the described content can be applied to the method of the present invention.

[0036] Embodiment 1: A preparation process of high-strength cement-based unburned pavement bricks, comprising the following steps: (1) Take waste glass powder (softening temperature is about 720-740℃) with a fineness of 400 mesh, shell powder, short basalt fiber (length 7mm, diameter 0.4mm) and sodium silicate. Mix the glass powder, shell powder, short 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 45wt.% for standby use.

[0037] (2) Add the coating slurry to the steel slag coarse aggregate with a particle size distribution between 10 and 15 mm, with the ratio of 1 g:3.5 ml. After mixing the two evenly, separate the coarse aggregate, and then place it in shell powder for coating again, so that the shell powder covers the coating slurry on the surface of the coarse aggregate completely. 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 standby use.

[0038] (3) Mix the pre-modified steel slag coarse aggregate with 4 mol / L hydrochloric acid in a ratio of 1 g:15 ml, stir evenly, and then soak for 60 minutes. After completion, filter and separate the coarse aggregate. Wash it twice with clean water, and then add it to the sodium hydroxide solution dispersed with graphene oxide in a ratio of 1 g:12 ml. - The concentration of is 0.3 mol / L, and the content of graphene oxide is 10 g / L. The obtained mixture is then heated to 50° C. and kept warm for 4 hours. After the mixture is heated to 50° C., the coarse aggregate is separated to obtain the improved steel slag coarse aggregate for later use.

[0039] (4) Take 870 parts by weight of 42.4 ordinary Portland cement, 1820 parts by weight of the improved 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), demould it after hardening, and then naturally cure it until the 28th day to obtain cement-based unburned pavement bricks, such as Figure 1 shown.

[0040] Performance test: The compressive strength of the cement-based unburned pavement brick prepared in this embodiment was tested according to the "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete" (GB / T50082-2009), and the result was 60.38 MPa.

[0041] Embodiment 2: A preparation process of high-strength cement-based unburned pavement bricks, comprising the following steps: (1) Take waste glass powder (softening temperature is about 720-740℃) with a fineness of 300 mesh, shell powder, short basalt fiber (length 10mm, diameter 0.5mm) and sodium silicate. Mix the glass powder, shell powder, short 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 40wt.% for standby use.

[0042] (2) Add the coating slurry to the steel slag coarse aggregate with a particle size distribution between 10 and 20 mm, with the 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 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 standby use.

[0043] (3) Mix the pre-modified steel slag coarse aggregate with 3 mol / L nitric acid in 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 the sodium hydroxide solution dispersed with graphene oxide in a ratio of 1 g: 20 ml. - The concentration of is 0.2 mol / L, and the content of graphene oxide is 7 g / L. The obtained mixture is then heated to 60° C. and kept warm for 3 hours. After the mixture is heated to 60° C., the coarse aggregate is separated to obtain the improved steel slag coarse aggregate for later use.

[0044] (4) Take 1000 parts by weight of 42.4 ordinary Portland cement, 2200 parts by weight of the improved 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), demould it after hardening, and then naturally cure it until the 28th day to obtain cement-based unburned pavement bricks, such as Figure 2 shown.

[0045] Performance test: The compressive strength of the cement-based unburned pavement brick prepared in this embodiment was tested according to the "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete" (GB / T50082-2009), and the result was 57.03 MPa.

[0046] Embodiment 3: A preparation process of high-strength cement-based unburned pavement bricks, comprising the following steps: (1) Take waste glass powder (softening temperature is about 720-740℃) with a fineness of 300 mesh, shell powder, short basalt fiber (length 5mm, diameter 0.2mm) and sodium silicate. Mix the glass powder, shell powder, short 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 50wt.% for standby use.

[0047] (2) Add the coating slurry to the steel slag coarse aggregate with a particle size distribution between 10 and 20 mm, with the ratio of the two being 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 covers the coating slurry on the surface of the coarse aggregate completely. 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 standby use.

[0048] (3) The pre-modified steel slag coarse aggregate was mixed with 6 mol / L acetic acid in a ratio of 1 g: 20 ml, stirred evenly, and then soaked for 70 min. 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 the ratio of the two being 1 g: 5 ml. - The concentration of is 0.4 mol / L, and the content of graphene oxide is 12 g / L. The obtained mixture is then heated to 40° C. and kept warm for 5 hours. After the mixture is heated to 40° C., the coarse aggregate is separated to obtain the improved steel slag coarse aggregate for later use.

[0049] (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 polycarboxylic acid water reducer. Mix the above components and stir for 2 minutes, then add clean water according to a water-cement ratio of 0.22 and stir evenly, pour the obtained slurry into a mold and press it into shape (pressure of 18 MPa, time of 30 seconds), demould it after hardening, and then naturally cure it until the 28th day to obtain cement-based unburned pavement bricks, such as Figure 3 shown.

[0050] Performance test: The compressive strength of the cement-based unburned pavement brick prepared in this embodiment was tested according to the "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete" (GB / T50082-2009), and the result was 61.79 MPa.

[0051] Embodiment 4: A preparation process of high-strength cement-based unburned pavement bricks, comprising the following steps: 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 the water-cement ratio of 0.26 and stir evenly, pour the obtained slurry into the mold and press it into shape (pressure of 20 MPa, time of 30 seconds), demould after hardening, and then naturally cure until the 28th day to obtain cement-based unburned pavement bricks, such as Figure 4 shown.

[0052] Performance test: The compressive strength of the cement-based unburned pavement brick prepared in this embodiment was tested according to the "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete" (GB / T50082-2009), and the result was 33.26 MPa.

[0053] Embodiment 5: A preparation process of high-strength cement-based unburned pavement bricks, comprising the following steps: (1) Mix steel slag coarse aggregate with a particle size distribution between 10 and 20 mm with 3 mol / L nitric acid in 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. The ratio of the two is 1 g: 20 ml. - The concentration of is 0.2 mol / L, and the content of graphene oxide is 7 g / L. The obtained mixture is then heated to 60° C. and kept warm for 3 hours. After the mixture is heated to 60° C., the coarse aggregate is separated to obtain the improved steel slag coarse aggregate for later use.

[0054] (2) Take 1000 parts by weight of 42.4 ordinary Portland cement, 2200 parts by weight of the improved 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), demould it after hardening, and then naturally cure it until the 28th day to obtain cement-based unburned pavement bricks, such as Figure 5 shown.

[0055] Performance test: The compressive strength of the cement-based unburned pavement brick prepared in this embodiment was tested according to the "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete" (GB / T50082-2009), and the result was 45.27 MPa.

[0056] Embodiment 6: A preparation process of high-strength cement-based unburned pavement bricks, comprising the following steps: (1) Pre-modified steel slag coarse aggregate (prepared by the same method as in Example 1) 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 clean water in which graphene oxide was dispersed, the ratio of the two being 1 g:12 ml, and the graphene oxide content in the clean water was 10 g / L. The obtained mixture was then heated to 50°C and kept warm for 4 hours. After completion, the coarse aggregate was separated to obtain the modified steel slag coarse aggregate for later use.

[0057] (2) Take 870 parts by weight of 42.4 ordinary Portland cement, 1820 parts by weight of the improved 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), demould it after hardening, and then naturally cure it until the 28th day to obtain cement-based unburned pavement bricks, such as Figure 6 shown.

[0058] Performance test: The compressive strength of the cement-based unburned pavement brick prepared in this embodiment was tested according to the "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete" (GB / T50082-2009), and the result was 56.18 MPa.

[0059] Embodiment 7: A preparation process of high-strength cement-based unburned pavement bricks, comprising the following steps: (1) Take shell powder with a fineness of 300 mesh, short basalt fiber (length 5 mm, diameter 0.2 mm) and sodium silicate. Mix the shell powder, short basalt fiber 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 50wt.%, and set aside.

[0060] (2) Add the coating slurry to the steel slag coarse aggregate with a particle size distribution between 10 and 20 mm, with the ratio of the two being 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 covers the coating slurry on the surface of the coarse aggregate completely. 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 standby use.

[0061] (3) The pre-modified steel slag coarse aggregate was mixed with 6 mol / L acetic acid in a ratio of 1 g: 20 ml, stirred evenly, and then soaked for 70 min. 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 the ratio of the two being 1 g: 5 ml. - The concentration of is 0.4 mol / L, and the content of graphene oxide is 12 g / L. The obtained mixture is then heated to 40° C. and kept warm for 5 hours. After the mixture is heated to 40° C., the coarse aggregate is separated to obtain the improved steel slag coarse aggregate for later use.

[0062] (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 polycarboxylic acid water reducer. Mix the above components and stir for 2 minutes, then add clean water according to a water-cement ratio of 0.22 and stir evenly, pour the obtained slurry into a mold and press it into shape (pressure of 18 MPa, time of 30 seconds), demould it after hardening, and then naturally cure it until the 28th day to obtain cement-based unburned pavement bricks, such as Figure 7 shown.

[0063] Performance test: The compressive strength of the cement-based unburned pavement brick prepared in this embodiment was tested according to the "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete" (GB / T50082-2009), and the result was 50.66 MPa.

[0064] Embodiment 8: A preparation process of high-strength cement-based unburned pavement bricks, comprising the following steps: (1) Take waste glass powder with a fineness of 300 mesh (softening temperature is about 720-740°C), short chopped basalt fiber (length 10 mm, diameter 0.5 mm) and sodium silicate. Mix the glass powder, short 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 40wt.% for standby use.

[0065] (2) Add the coating slurry to the steel slag coarse aggregate with a particle size distribution between 10 and 20 mm, with the 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 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 standby use.

[0066] (3) Mix the pre-modified steel slag coarse aggregate with 3 mol / L nitric acid in 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 the sodium hydroxide solution dispersed with graphene oxide in a ratio of 1 g: 20 ml. - The concentration of is 0.2 mol / L, and the content of graphene oxide is 7 g / L. The obtained mixture is then heated to 60° C. and kept warm for 3 hours. After the mixture is heated to 60° C., the coarse aggregate is separated to obtain the improved steel slag coarse aggregate for later use.

[0067] (4) Take 1000 parts by weight of 42.4 ordinary Portland cement, 2200 parts by weight of the improved 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), demould it after hardening, and then naturally cure it until the 28th day to obtain cement-based unburned pavement bricks, such as Figure 8 shown.

[0068] Performance test: The compressive strength of the cement-based unburned pavement brick prepared in this embodiment was tested according to the "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete" (GB / T50082-2009), and the result was 48.45 MPa.

[0069] Embodiment 9: A preparation process of high-strength cement-based unburned pavement bricks, comprising the following steps: Take 800 parts by weight of 42.4 ordinary Portland cement, 1700 parts by weight of improved steel slag coarse aggregate (preparation method is the same 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 polycarboxylic acid water reducer. Mix the above components and stir for 2 minutes, then add clean water according to a water-cement ratio of 0.22 and stir evenly, pour the obtained slurry into a mold for pressing and molding (pressure of 18 MPa, time of 30 seconds), demould after hardening, and then naturally cure until the 28th day to obtain cement-based unburned pavement bricks, such as Fig. 9 shown.

[0070] Performance test: The compressive strength of the cement-based unburned pavement brick prepared in this embodiment was tested according to the "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete" (GB / T50082-2009), and the result was 54.31 MPa.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still repair the technical solutions recorded in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any repair, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A process for preparing high-strength cement-based unburned pavement bricks, characterized in that: The steps include: (1) Mix glass powder, shell powder, chopped basalt fiber, sodium silicate and water and stir evenly to form a coating slurry for later use; (2) adding the coating slurry to the steel slag coarse aggregate, mixing 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, cooling after completion, and obtaining 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) Taking silicate cement, the modified steel slag coarse aggregate, river sand fine aggregate, fly ash, mineral powder, flexible fiber filaments and water reducing agent as raw materials, mixing the raw materials evenly and adding water to mix evenly, pouring the obtained slurry into a mold for pressing and forming, and curing after demolding to obtain cement-based unburned pavement bricks.

2. The preparation process of high-strength cement-based unburned pavement brick according to claim 1, characterized in that: 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; Alternatively, in step (1), the water is added according to the solid content of the coating slurry being 40-50 wt.%; Alternatively, in step (1), the length of the chopped basalt fiber is 5-10 mm and the diameter is 0.2-0.5 mm; Alternatively, in step (1), the fineness of the glass powder and shell powder is 300-400 mesh.

3. The preparation process of the high-strength cement-based unburned pavement 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; Alternatively, in step (2), the particle size of the steel slag coarse aggregate is 10-20 mm; Alternatively, in step (2), the shell powder can completely cover the coating slurry on the surface of the coarse aggregate.

4. The preparation process of high-strength cement-based unburned pavement brick according to claim 1, characterized in that: In step (2), the sintering time is 20 to 30 minutes.

5. The preparation process of high-strength cement-based unburned pavement brick 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; Alternatively, in step (3), the acid solution comprises: at least one of hydrochloric acid, nitric acid, and acetic acid; Alternatively, in step (3), the concentration of the acid solution is 3-6 mol / L; Alternatively, in step (3), the soaking time is 50 to 70 minutes; Alternatively, in step (3), clean water is used to perform the cleaning to remove the acid remaining in the aggregate.

6. The process for preparing high-strength cement-based unburned pavement 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.

7. The process for preparing high-strength cement-based unburned pavement bricks according to claim 1, characterized in that: In step (3), the OH in the alkaline suspension - The concentration is 0.2~0.4mol / L; Alternatively, the OH - Provided by at least one of sodium hydroxide and potassium hydroxide.

8. 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; In step (3), the heating and heat preservation temperature is 40-60° C. and the time is 3-5 hours.

9. The process for preparing high-strength cement-based unburned pavement bricks according to claim 1, characterized in that: In step (4), the proportions of the components in the raw materials are: 800-1000 parts by weight of silicate 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, and the water is added according to a water-cement ratio of 0.22-0.

3.

10. The process for preparing high-strength cement-based unburned pavement bricks according to any one of claims 1 to 9, 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; Alternatively, in step (4), the length of the flexible fiber filament is 10-30 mm and the diameter is 0.2-0.5 mm; Alternatively, in step (4), the water reducer includes at least one of a polycarboxylate water reducer, a naphthalene-based water reducer, and a lignin sulfonate water reducer.

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