Method for preparing alkali-resistant curbstone using marble saw mud with high chromium content, curbstone and application thereof

Abstract

The present application provides a method, curbstone and application for preparing alkali-resistant curbstones using marble sawdust with a high chromium content, and belongs to the field of building material technology. The method comprises: step one, obtaining marble sawdust activation material; step two, adding glucose and quicklime and mixing evenly; step three, adding surfactant, expanded graphite, polyvinyl alcohol and talcum powder and mixing evenly; step four, adding stone-making base material, reinforcing agent, water-reducing agent and appropriate amount of water and stirring thoroughly; step five, loading into a stone-making mold, static pressing and performing standard curing for 10 to 20 days to obtain the alkali-resistant curbstone. The method provided in the present application, after processing the marble sawdust and optimizing other components, can make a larger amount of marble sawdust more effectively filled, dispersed and combined in the mixture system, thereby improving the strength, alkali resistance and salt-freeze resistance of the curbstone, and having good economic and environmental benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and particularly relates to a method for preparing an alkali-resistant curbstone by utilizing marble saw mud with a high chromium content. Background Art

[0002] Marble sawdust is solid waste such as grinding materials and cutting scraps generated during the marble cutting process. Piling up marble sawdust not only occupies a large area of land, but also easily causes dust and water pollution.

[0003] In the existing technology, a large proportion of low-value-added sawdust with a particle size greater than 60 mesh is usually used to prepare building materials such as concrete and cement bricks. However, a large amount of waste stone powder raw materials currently have serious environmental index violations. For example, some marble sawdust has been found to have a water-soluble hexavalent chromium content far exceeding the environmental index requirements for concrete (≤200mg / t). If directly mixed with cement and sand to make concrete or bricks, it will not only fail to meet national standards, but also cause serious environmental pollution and affect product performance. In addition, this type of sawdust raw material is difficult to process using conventional reducing agents such as ferrous sulfate and reduction reaction methods. This is because the reduction reaction of the above-mentioned reducing agents requires acidic conditions. Marble-derived sawdust contains at least 60% calcium carbonate. Conventional processing methods will not only cause significant loss of the stone powder raw material, but also make the generated trivalent iron ions difficult to remove, making it unsuitable for use in masonry or concrete. At the same time, some studies have shown that stone powder solid waste containing a large amount of calcium carbonate, when mixed with cement and other raw materials to make concrete, has low activity and a slower hydration reaction than cement. Although it can be used as an admixture and cementitious material to increase the density and durability of the product, it has poor bonding with the cement base, which in turn causes the strength of the product to decrease, and can only be used at a smaller dosage.

[0004] Stone alkali reversion occurs when alkaline substances like calcium hydroxide in cement dissolve in humid or water-soaked environments, migrate through the pores, and precipitate as white powder on the stone surface. This phenomenon not only affects the appearance but also damages the internal and edge structures, significantly impacting the stone's service life. Curbstones are often located between the divider and the road surface on urban roads, between the sidewalk and the road surface, at the edge of the central divider, on the right side of the roadway, or on the outer edge of the shoulder. Due to road erosion, rain, snow, and other conditions, they are repeatedly exposed to water or partially immersed in water. Traditional stone or concrete is more susceptible to alkali reversion in such environments. Summary of the Invention

[0005] In order to solve the above problems, the present application aims to provide a method for effectively and in large quantities utilizing marble saw mud containing a high water-soluble hexavalent chromium content, while improving the environmental protection issues of marble saw mud, further improving the bonding with the cement base material and giving full play to the filling effect of the saw mud to increase the density of the product, thereby preparing a curbstone with significantly improved mechanical strength and anti-alkali resistance.

[0006] In one aspect, the present application provides a method for preparing an alkali-resistant curbstone using marble saw mud with a high chromium content, the method comprising:

[0007] Step 1: Vibrate and screen the marble saw mud to obtain a sieve, and continue to vibrate the sieve for 10 to 60 minutes to obtain an activated marble saw mud material for standby use;

[0008] Step 2: adding an appropriate amount of water to the marble saw mud activation material and stirring thoroughly, then adding glucose and quicklime and mixing evenly to obtain a first mixture;

[0009] Step 3: adding a surfactant, expanded graphite, polyvinyl alcohol and talc to the first mixture and mixing them uniformly to obtain a second mixture;

[0010] Step 4: adding a stone-making base material, a reinforcing agent, a water-reducing agent and an appropriate amount of water to the second mixture and stirring thoroughly to obtain a stone-making mixture;

[0011] Step 5: The stone-making mixture is placed into a stone-making mold, and after static pressure molding, standard curing is performed for 10 to 20 days to obtain the anti-alkali curbstone;

[0012] The water-soluble hexavalent chromium content in the marble saw mud is greater than 200 mg / t; and the stone-making base materials include cement, crushed stone, fly ash and slag powder.

[0013] In one embodiment, the water-soluble hexavalent chromium content in the marble saw mud is 200-1000 mg / t, preferably 300-800 mg / t, and more preferably 400-700 mg / t.

[0014] In one embodiment, the mass percentage of calcium carbonate in the marble saw mud is ≥60%, preferably 60% to 95%.

[0015] In one embodiment, in step 1, the vibration screening can be performed using a conventional commercially available vibration screening machine.

[0016] In one embodiment, the particle size of the sieved material in step 1 is 40-60 mesh.

[0017] In one embodiment, the vibration frequency is 150-250 times / min, and the vibration amplitude is 0-5 mm.

[0018] It is understandable that the "high chromium content" mentioned in this application refers to a high water-soluble hexavalent chromium content. This application uses marble saw mud with a water-soluble hexavalent chromium content higher than the environmental index requirements as raw material. After vibration screening and activation, on the one hand, its particle size is made suitable for replacing medium sand as fine aggregate. On the other hand, it can be better dissolved in the water-soluble hexavalent chromium in the saw mud after the subsequent addition of water. Then, after adding quicklime and excess glucose, in the alkaline environment of quicklime meeting water to form mature lime calcium hydroxide and under the exothermic conditions, the hexavalent chromium can be quickly reduced by glucose to form trivalent chromium, and further to form calcium chromate and amphoteric chromium hydroxide, thereby solving the environmental protection problem of saw mud and reducing the most The porosity of the final stone mixture increases the density and strength of the final curb, while also reducing the channels for water to enter the stone after soaking and for alkaline substances to migrate outward. Furthermore, during actual curb use, it can react with alkaline substances precipitated from the stone under alkali-reversion conditions, reducing the generation of alkaline substances and improving the curb's resistance to alkali reversion. It can also react with chloride ions in salt water to form chlorochromate, which protects the stone aggregate and helps improve the curb's resistance to salt freezing, making it more suitable for rainy and snowy weather and resistant to corrosion from industrial salt de-icing agents, thereby extending the curb's service life. Furthermore, the calcium gluconate produced by the reduction reaction can also act as a retarder and binder in the mixture, especially when quicklime releases a large amount of heat when in contact with water. This further enhances the bonding ability of the sawdust and the hydrated products of the stone-making base material, while extending the setting time and improving workability. This helps further maximize the filling properties of the sawdust and improves the curb's strength.

[0019] In one embodiment, the method uses the following raw material components, calculated by mass: 50-65 parts of marble saw mud activation material, 0.1-3 parts of glucose, 1-5 parts of quicklime, 0.1-1 parts of surfactant, 2-6 parts of expanded graphite, 0.1-1 parts of polyvinyl alcohol, 1-2 parts of talc, 5-20 parts of cement, 70-100 parts of crushed stone, 5-8 parts of fly ash, 10-20 parts of slag powder, 1-3 parts of reinforcing agent, 0.1-1 parts of water reducer, and 6-12 parts of water.

[0020] In one embodiment, one-half to two-thirds of the 6-12 parts of water are added in step two, and the remaining water is added in step four.

[0021] In one embodiment, the surfactant is maleic anhydride acrylic acid copolymer sodium salt, with a molecular weight of 300-800, and a monomer molar ratio of maleic acid to acrylic acid of 1:(0.6-0.8).

[0022] The sodium salt of maleic anhydride acrylic acid copolymer, when used as a concrete surfactant, exhibits excellent dispersibility for carbonates, significantly improving the uniformity of the hydrated product after mixing sawdust with stone-making base materials. Compared to other surfactants, it is non-foaming, helping to enhance the density of the mix and reduce porosity. Furthermore, the copolymer, with a specific molar ratio of maleic acid and acrylic acid monomers, also possesses a certain degree of viscosity, which helps enhance viscosity and improve the bonding between sawdust, crushed stone aggregate, and cement hydration products.

[0023] In one embodiment, the expansion ratio of the expanded graphite is 250 to 350 times.

[0024] In one embodiment, the particle size of the talc is 400-600 mesh.

[0025] Expanded graphite and talc significantly enhance the plasticity of the mix, significantly increasing the stone's compressive and flexural strength. Their hydrophobicity also helps reduce the stone's water absorption and minimizes the dissolution of alkaline substances within it. Furthermore, their strong thixotropy effectively reduces porosity in the mix, improving density and impermeability, and reducing the migration of alkaline substances within the stone, thereby enhancing its resistance to alkali reversion.

[0026] Thickeners and thixotropic agents play an important role in the coating and uniformity between cement and aggregate in concrete. The curbstone raw materials of this application are compounded with sodium salt of maleic anhydride acrylic acid copolymer with a specific monomer ratio and expanded graphite and talc powder with a specific expansion multiple, which further improves the overall uniformity and density of the mixture, and significantly improves the binding and dispersion ability of sawdust in the mixture system, which is beneficial to improving the strength, durability, and anti-alkali and salt-freeze resistance of the curbstone.

[0027] In one embodiment, the molecular weight of the polyvinyl alcohol is 20,000-90,000.

[0028] Among them, polyvinyl alcohol with a larger molecular weight has good dispersibility for expanded graphite, preventing graphite aggregation from affecting strength; on the other hand, it can also serve as a coagulant, and cooperate with the calcium gluconate retarder generated in the previous step to adjust the setting time after stone forming.

[0029] In one embodiment, the reinforcing agent is selected from one or more of potassium silicate, sodium silicate, and aluminum silicate.

[0030] Among them, the above-mentioned enhancer can accelerate the maturation and hardening of cement, significantly improve the early strength of stone-making mixture, enhance its waterproof and anti-seepage properties, and also improve the stability of trivalent chromium in the mixture and inhibit its oxidation.

[0031] In one embodiment, the water reducer is an aliphatic high-efficiency water reducer.

[0032] In one embodiment, the cement is P·O 42.5 cement.

[0033] In one embodiment, the crushed stone is 5-20 mm continuously graded crushed stone.

[0034] In one embodiment, the fly ash is Class II fly ash.

[0035] In one embodiment, the slag powder is S95 slag powder.

[0036] In one embodiment, the uniform mixing method in each step of the method is stirring. Optionally, a commercially available concrete mixer can be used for stirring, and the stirring speed is 20-40 r / min, for example, 35 r / min; the stirring time of each step is preferably 1-10 min.

[0037] In one embodiment, the total stirring time of steps 2 to 4 does not exceed 40 minutes.

[0038] In one embodiment, the static pressure forming can be performed using existing commercially available curbstone production equipment, such as a fully automatic curbstone hydraulic press.

[0039] In one embodiment, in step five, the static pressure molding pressure is 20-25 MPa.

[0040] On the other hand, the present application also provides a curbstone prepared using the method.

[0041] On the other hand, the present application also provides the use of the curbstone in construction projects, road projects, municipal projects or garden projects.

[0042] This application has at least the following beneficial effects:

[0043] The method for preparing curbstones provided in the present application uses marble sawdust containing calcium carbonate as a main component and a high content of water-soluble hexavalent chromium as a raw material. After vibratory screening and reduction treatment of the sawdust raw material, not only is the hexavalent chromium content in the raw material effectively reduced, improving its environmental properties, but it also helps to reduce porosity, increase the density of the stone-making admixture, increase adhesion and strength, and effectively improve the curbstone's resistance to alkali reversion and salt freezing.

[0044] The curbstone preparation method provided in the present application, while utilizing marble sawn mud as raw material, also optimizes other components in the stone-making admixture, and with the cooperation of components having certain viscosity-increasing and thixotropic properties, can enable a larger amount of marble sawn mud to be more effectively filled, dispersed and combined in the mixture system, thereby being beneficial to improving the strength, alkali resistance and salt-freeze resistance of the curbstone, while also significantly increasing the utilization rate of marble sawn mud, with good economic and environmental benefits. DETAILED DESCRIPTION

[0045] In order to more clearly illustrate the overall concept of the application, the following is described in detail in the form of embodiments. In the following description, a large amount of specific details are provided so that a more thorough understanding of the application is provided. However, it will be apparent to those skilled in the art that the application can be implemented without the need for one or more of these details. In other examples, in order to avoid confusion with the application, some technical features well known in the art are not described.

[0046] Unless otherwise specified, the production processes, experimental methods or detection methods involved in the embodiments of the present invention are all conventional methods in the prior art, and their names and / or abbreviations are conventional names in the field and are very clear and unambiguous in the relevant fields of use. Those skilled in the art can understand the conventional process steps based on the names and apply the corresponding equipment to implement them according to conventional conditions or the conditions recommended by the manufacturer.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0048] The various instruments, equipment, raw materials or reagents used in the examples of the present invention are not particularly limited in their sources and, unless otherwise specified, can be obtained from conventional commercial channels or prepared according to conventional methods well known to those skilled in the art.

[0049] In the following examples, marble sawdust was solid waste generated from marble processing at a stone processing plant in Zibo. Its calcium carbonate content was 65% to 85%, and its water-soluble hexavalent chromium content was 300 to 800 mg / t. Glucose was commercially available industrial-grade glucose. Maleic anhydride and acrylic acid copolymer sodium salt was purchased commercially with a molecular weight of 300 to 800, or it could be prepared in-house using known methods. Polyvinyl alcohol was commercially available, model 24-88P, with a molecular weight of 24,000 to 88,000. Cement was commercially available P·O 42.5 cement. Slag powder was commercially available S95 slag powder. Fly ash was commercially available Class II fly ash. Crushed stone was commercially available 5 to 20 mm continuously graded crushed stone. All other raw materials or components were commercially available conventional construction materials.

[0050] In the following embodiments, a common commercial vibrating screening machine may be used for vibration screening, a common commercial curbstone hydraulic press may be used for static pressure forming, and a common commercial concrete mixer may be used for mixing and stirring.

[0051] Example 1

[0052] This embodiment provides a method for preparing an anti-alkali curbstone using marble sawdust with a high chromium content, the method specifically comprising the following steps:

[0053] Step 1: Vibrate and screen the marble saw mud to obtain a sieved material, and continue to vibrate the sieved material for 10 to 60 minutes to obtain the marble saw mud activated material for standby use;

[0054] Step 2: Add appropriate amount of water to the marble saw mud activation material and stir thoroughly, then add glucose and quicklime and mix well to obtain a first mixture;

[0055] Step 3: adding a surfactant, expanded graphite, polyvinyl alcohol and talc to the first mixture and mixing them uniformly to obtain a second mixture;

[0056] Step 4: Add the stone-making base material, reinforcing agent, water-reducing agent and appropriate amount of water to the second mixture and stir thoroughly to obtain a stone-making mixture;

[0057] Step 5: Place the stone mixture into the stone mold, statically press and shape it, and then perform standard curing for 10 to 20 days to obtain the anti-alkali curbstone;

[0058] Among them, the water-soluble hexavalent chromium content in marble saw mud is 573 mg / t; the stone-making base materials include cement, crushed stone, fly ash and slag powder.

[0059] In step 1 of the above method, the marble sawdust is vibrated and sieved at a frequency of 220 vibrations / min and an amplitude of 0-5 mm. The sieved material with a particle size of 40-60 mesh is collected and vibrated further at the aforementioned parameters for 30 minutes to obtain an activated marble sawdust material for later use. The following raw materials, calculated by weight, are prepared: 58 parts of the activated marble sawdust material prepared in step 1, 1 part of industrial-grade glucose, 1.5 parts of quicklime, 0.5 parts of sodium maleic anhydride acrylic acid copolymer (a molar ratio of maleic acid to acrylic acid of 1:0.7, molecular weight approximately 617), 5 parts of expanded graphite (expansion factor 250), 0.5 parts of polyvinyl alcohol, 1 part of talc, 15 parts of cement, 85 parts of crushed stone, 7 parts of fly ash, 15 parts of slag powder, 0.5 parts of potassium silicate, 1 part of aluminum silicate, 0.6 parts of an aliphatic high-efficiency water reducer, and 12 parts of water. The mixture is stirred at 35 rpm.

[0060] In step 2 of the above method, 7 parts of water are added to the marble saw mud activation material, stirred for 1 to 3 minutes, and then industrial-grade glucose and quicklime are added and mixed evenly, and allowed to stand for 1 to 2 minutes to obtain a first mixture.

[0061] In step three of the above method, sodium salt of maleic anhydride acrylic acid copolymer, expanded graphite, polyvinyl alcohol and talc are added to the first mixture prepared in step two and mixed thoroughly to obtain a second mixture.

[0062] In step 4 of the above method, cement, crushed stone, fly ash, slag powder, potassium silicate, aluminum silicate and 5 parts of water are added to the second mixture obtained in step 3, and the mixture is thoroughly stirred to obtain a stone-making mixture.

[0063] In step five of the above method, the stone-making mixture prepared in step four is loaded into a stone-making mold for the curbstone, and after static pressure molding at 22 MPa, standard curing is carried out for 15 days before the stone-making mold is released from the warehouse.

[0064] Example 2

[0065] The preparation method of the curbstone in this embodiment is substantially the same as that in Example 1, except that, in parts by mass, the following raw material components are prepared: 62 parts of marble sawdust activated material (water-soluble hexavalent chromium content is 465 mg / t), 1.5 parts of industrial-grade glucose, 2 parts of quicklime, 0.8 parts of sodium salt of maleic anhydride acrylic acid copolymer (the molar ratio of maleic acid and acrylic acid monomers is 1:0.7, and the molecular weight is about 617), 5 parts of expanded graphite (expansion multiple is 300 times), 0.5 parts of polyvinyl alcohol, 1 part of talc powder, 10 parts of cement, 85 parts of crushed stone, 7 parts of fly ash, 15 parts of slag powder, 0.5 parts of potassium silicate, 1 part of aluminum silicate, 0.5 parts of aliphatic high-efficiency water reducer, and 12 parts of water.

[0066] Example 3

[0067] The preparation method of the curbstone in this embodiment is substantially the same as that in Example 1, except that, in parts by mass, the following raw material components are prepared: 53 parts of marble sawdust activated material (water-soluble hexavalent chromium content is 638 mg / t), 1.5 parts of industrial-grade glucose, 2 parts of quicklime, 0.4 parts of sodium salt of maleic anhydride acrylic acid copolymer (the molar ratio of maleic acid and acrylic acid monomers is 1:0.7, and the molecular weight is about 617), 5 parts of expanded graphite (expansion multiple is 350 times), 0.5 parts of polyvinyl alcohol, 1 part of talc powder, 18 parts of cement, 85 parts of crushed stone, 7 parts of fly ash, 15 parts of slag powder, 0.5 parts of potassium silicate, 1 part of aluminum silicate, 0.7 parts of aliphatic high-efficiency water reducer, and 12 parts of water.

[0068] The curbstones produced in Examples 1 to 3 are designated as Examples 1# to 3#, respectively. Furthermore, the present application further optimized the raw material components. Specifically, the molar ratio of maleic acid and acrylic acid in the sodium salt of maleic anhydride acrylic acid copolymer in Example 1 was replaced with 1:0.5 (molecular weight approximately 559) and 1:1 (molecular weight approximately 703), respectively. The resulting curbstone samples were designated as Examples 4# and 5#, respectively. The expansion ratio of the expanded graphite in Example 1 was increased to 200 times and 400 times, respectively. The resulting curbstone samples were designated as Examples 6# and 7#, respectively. Furthermore, a selected activated marble sawdust material with a water-soluble hexavalent chromium content of less than 200 mg / t (measured water-soluble hexavalent chromium content of 164 mg / t) was selected from the raw material components of Example 1, and 3.5 parts of calcium gluconate were used in place of industrial-grade glucose and quicklime. The resulting curbstone sample was designated as Example 8#.

[0069] Comparative Example 1

[0070] A C30 concrete curbstone was used as a comparative example. Its formulation consisted of 30 parts cement, 70 parts medium sand (particle size 0.25-0.5 mm), 120 parts crushed stone, and 20 parts water. The preparation method involved mixing and stirring, and the stone-making conditions were the same as those in Step 5 of Example 1. The resulting curbstone sample was designated D1#.

[0071] Four samples were prepared from each of the above examples and comparative examples. After 10 days of curing, their performance was tested according to the method specified in the national building materials industry standard "JC / T899-2016 Concrete Curbstone," and the average results were calculated. The water-soluble hexavalent chromium content of the finished product was measured after static pressing; salt-freeze resistance was measured as the average mass loss after ND28 salt-freeze cycles; and efflorescence was tested according to the method specified in the national standard "GB / T2542-2012 Test Methods for Masonry Bricks." To better reflect the changing weather conditions of actual curbstone applications, the method of soaking in water for 7 days and then drying was replaced with soaking in water for 3 days, drying for 2 hours, and then repeating the soaking process for a total of 15 days. The samples were then observed for white powder precipitation and for rotting or falling brick edges.

[0072] The specific test results are shown in Table 1:

[0073]

[0074] As shown in Table 1, compared to curbstones made from traditional C30 fine stone concrete, the curbstones prepared using the preparation method of the present application have superior flexural and compressive strengths and lower water absorption. The mass loss under salt-freezing conditions is significantly reduced. After 15 days of cyclic soaking in water, no alkaline powder is precipitated, and the stone edges remain intact and undamaged. These curbstones are suitable for the actual use of curbstones in construction projects, road projects, municipal projects, or garden projects. Furthermore, the method provided by the present application allows for the use of large amounts of marble sawn mud with a high hexavalent chromium content when preparing curbstones. This significantly reduces the hexavalent chromium content in the finished product, resulting in significant economic and environmental benefits. Furthermore, the selection of specific components in the system has a certain influence on the various properties of the final curbstone. The curbstones prepared in Examples 1 to 3 exhibit more advantageous mechanical strength, salt-freezing resistance, and alkali reversion resistance, making them more preferred embodiments of the present application.

[0075] The foregoing is merely an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. A method for preparing alkali-resistant curbstones using marble sawdust with a high chromium content, characterized in that: The method comprises: Step 1: Vibrate and screen the marble saw mud to obtain a sieve, and continue to vibrate the sieve for 10 to 60 minutes to obtain an activated marble saw mud material for standby use; Step 2: adding an appropriate amount of water to the marble saw mud activation material and stirring thoroughly, then adding glucose and quicklime and mixing evenly to obtain a first mixture; Step 3: adding a surfactant, expanded graphite, polyvinyl alcohol and talc to the first mixture and mixing them uniformly to obtain a second mixture; Step 4: adding a stone-making base material, a reinforcing agent, a water-reducing agent and an appropriate amount of water to the second mixture and stirring thoroughly to obtain a stone-making mixture; Step 5: The stone-making mixture is placed into a stone-making mold, and after static pressure molding, standard curing is performed for 10 to 20 days to obtain the anti-alkali curbstone; The water-soluble hexavalent chromium content in the marble saw mud is greater than 200 mg / t; and the stone-making base materials include cement, crushed stone, fly ash and slag powder.

2. The method according to claim 1, characterized in that The particle size of the sieved material in step 1 is 40-60 mesh; And / or, the vibration frequency of the vibration screening is 150-250 times / min, and the vibration amplitude is 0-5mm.

3. The method according to claim 2, characterized in that The method adopts the following raw material components in parts by mass: 50-65 parts of marble saw mud activation material, 0.1-3 parts of glucose, 1-5 parts of quicklime, 0.1-1 parts of surfactant, 2-6 parts of expanded graphite, 0.1-1 parts of polyvinyl alcohol, 1-2 parts of talc, 5-20 parts of cement, 70-100 parts of crushed stone, 5-8 parts of fly ash, 10-20 parts of slag powder, 1-3 parts of reinforcing agent, 0.1-1 parts of water reducer, and 6-12 parts of water.

4. The method according to claim 3, characterized in that Add one-half to two-thirds of 6 to 12 parts of water in step 2, and the remaining water in step 4.

5. The method according to claim 3, characterized in that The surfactant is maleic anhydride acrylic acid copolymer sodium salt, with a molecular weight of 300-800, and a monomer molar ratio of maleic acid to acrylic acid of 1: (0.6-0.8); And / or, the expansion ratio of the expanded graphite is 250 to 350 times.

6. The method according to claim 3, characterized in that The reinforcing agent is selected from one or more of potassium silicate, sodium silicate and aluminum silicate; and / or, the molecular weight of the polyvinyl alcohol is 20,000 to 90,000; And / or, the water reducer is an aliphatic high-efficiency water reducer.

7. The method according to claim 1, characterized in that The cement is P·O 42.5 cement; And / or, the crushed stone is 5-20 mm continuously graded crushed stone; and / or, the fly ash is Class II fly ash; And / or, the slag powder is S95 slag powder.

8. The method according to claim 1, characterized in that The total stirring time from step 2 to step 4 does not exceed 40 minutes; And / or, in step five, the static pressure forming pressure is 20-25 MPa.

9. A curbstone prepared by the method according to any one of claims 1 to 8.

10. Use of the curbstone according to claim 9 in construction projects, road projects, municipal projects or garden projects.

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