A preparation method of light-weight thermal insulation cement-based material for aquaculture

Abstract

The application discloses a preparation method of a light thermal insulation cement-based material for aquaculture, and comprises the following steps: (1) placing expanded vermiculite particles in an alkali solution and keeping warm under heating conditions; after completion, the obtained expanded vermiculite particles are washed, dried, and modified thermal insulation aggregates are obtained; (2) dispersing nano-silicon dioxide in water to form a dispersion liquid, then adding a polycarboxylic acid water reducing agent and stirring uniformly, then adding sodium borohydride and stirring uniformly, and then standing; after completion, the obtained dispersion liquid is dried to remove excess water, ground, and a chromium-reducing additive is obtained; (3) taking the following raw materials: a silicate cement, the modified thermal insulation aggregates, glass beads, a filler, the chromium-reducing additive, and fibers; the raw materials are uniformly mixed, water is added, and stirring is uniformly carried out, and the thermal insulation cement-based material is obtained. The application can not only reduce high-toxicity hexavalent chromium into low-toxicity trivalent chromium, but also solidify the chromium element, so that the water-soluble chromium element in the material is effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of marine concrete preparation technology, specifically to a method for preparing lightweight thermal insulation cement-based materials for aquaculture. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Cement-based materials are indispensable building materials in aquaculture. Concrete aquaculture ponds are widely used due to their advantages such as low cost, durability, ease of construction, and maintenance. In low ambient temperatures, heating equipment is typically required to maintain the water temperature within the pond. At this time, aquaculture ponds constructed with insulated cement-based materials effectively reduce heat loss from the water and maintain the pond's temperature.

[0004] Currently, the insulating cement-based materials used in the construction of aquaculture ponds mainly use ordinary Portland cement as the cementitious component. However, the raw materials for producing this type of cement are primarily ores and industrial solid waste, resulting in cement clinker that typically contains soluble hexavalent chromium (Cr(VI)). Furthermore, during the crushing and grinding process of these raw materials and the resulting cement clinker, metal powder worn off from the metal parts of the equipment also introduces some chromium. my country's national standard, "Limits and Determination Methods for Water-Soluble Chromium (VI) in Cement" (GB31893-2015), clearly stipulates that the water-soluble chromium (VI) in cement must not exceed 10 mg / kg. However, when using this type of cement clinker to construct aquaculture ponds, water-soluble chromium (VI) can still easily migrate into the pond, affecting water quality. Therefore, measures need to be taken to minimize the water-soluble chromium (VI) content in the prepared insulating cement-based materials. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a method for preparing lightweight thermal insulation cement-based materials for aquaculture. This method not only reduces highly toxic hexavalent chromium to less toxic trivalent chromium but also solidifies the chromium element, effectively reducing the water-soluble chromium content in the material and making it more suitable for constructing aquaculture ponds. Specifically, the technical solution of this invention is as follows.

[0006] A method for preparing a lightweight thermal insulation cement-based material for aquaculture includes the following steps:

[0007] (1) Place the expanded vermiculite particles in an alkaline solution and keep them warm under heating conditions. After completion, wash the obtained expanded vermiculite particles to remove the residual alkaline solution, and dry them to obtain modified thermal insulation aggregate for later use.

[0008] (2) Disperse nano-silica in water to form a dispersion, then add polycarboxylate superplasticizer and stir until uniform, then add sodium borohydride and stir until uniform, and let stand. After completion, dry to remove excess water, grind to obtain chromium-reducing additive, and set aside for later use.

[0009] (3) Take the following raw materials: silicate cement, the modified thermal insulation aggregate, glass microspheres, filler, the chromium-reducing admixture, and fiber. Mix the above raw materials evenly, add water and stir until uniform to obtain the thermal insulation cement-based material.

[0010] Further, in step (1), the ratio of the expanded vermiculite particles to the alkaline solution is 1g: 25~50ml. Optionally, the particle size of the expanded vermiculite particles is 2~6mm.

[0011] Further, in step (1), the concentration of the alkaline solution is 1~3 mol / L. Optionally, the alkaline solution includes at least one of sodium hydroxide solution, potassium hydroxide solution, etc.

[0012] Furthermore, in step (1), the heating temperature is 60~80℃ and the heat preservation time is 4~5 hours.

[0013] Further, in step (2), the polycarboxylate superplasticizer is 0.4~0.75% of the mass of nano-silica.

[0014] Further, in step (2), the mass ratio of sodium borohydride to nano-silica is 1.8~2.3:1.

[0015] Further, in step (2), the drying method includes at least one of heating, freeze drying, etc. Optionally, the heating temperature is 70~90℃.

[0016] Further, in step (3), the proportions of each component in the raw material are as follows: 215-240 parts by weight of silicate cement, 450-530 parts by weight of the modified thermal insulation aggregate, 32-48 parts by weight of glass microspheres, 20-30 parts by weight of filler, 0.4-0.8 parts by weight of the chromium-reducing admixture, and 10-15 parts by weight of fiber.

[0017] Further, in step (3), water is added at a water-cement ratio of 0.42 to 0.48.

[0018] Further, in step (3), the filler includes at least one of calcium carbonate powder, mica powder, quartz powder, etc. Optionally, the fineness of the filler is 300~500 mesh.

[0019] Further, in step (3), the fiber includes at least one of polyethylene fiber, polypropylene fiber, polyacrylonitrile fiber, basalt fiber, etc. Optionally, the length of the fiber is 5~20mm.

[0020] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

[0021] This invention uses alkali to treat expanded vermiculite, forming a modified insulating aggregate. This not only gives the cement-based material of this invention excellent thermal insulation performance, but also allows the silicon-oxygen tetrahedra in the expanded vermiculite to depolymerize under the action of alkali, forming products containing silanol groups such as -Si(OH)3. Furthermore, due to the porous nature of expanded vermiculite, the modified vermiculite, with its large specific surface area, can provide a large number of silanol groups. When added to silicate cement, it not only utilizes its adsorption capacity to enrich chromium into the pores of the aggregate, but also utilizes the silanol groups to complex the chromium in the cement. Simultaneously, the calcium hydroxide produced during cement hydration enters the aggregate, promoting the conversion of -Si(OH)3 into hydrated calcium silicate. This cementitious product, after solidification, can fix the complexed chromium within it, effectively preventing the dissolution of chromium.

[0022] Furthermore, the chromium-reducing admixture of the present invention can not only reduce highly toxic hexavalent chromium to less toxic trivalent chromium, but also solidify chromium, further reducing the water-soluble chromium in the material. To this end, the present invention first uses a polycarboxylate superplasticizer to modify the surface of nano-silica. Utilizing the electrostatic adsorption provided by the main chain of the polycarboxylate superplasticizer, a large number of superplasticizer molecules are loaded onto the surface of the nano-silica. Then, the present invention uses sodium borohydride to reduce the carboxyl groups on the superplasticizer molecules to hydroxyl groups. Because the polycarboxylate superplasticizer contains a large number of carboxyl groups, the surface of the resulting nano-silica particles is loaded with a large number of hydroxyl groups. Simultaneously, the remaining sodium borohydride, together with the nano-silica, forms the chromium-reducing admixture. When added to the thermal insulation cement-based material of the present invention, on the one hand, the hydroxyl groups on the surface of the nano-silica particles can complex and capture chromium; on the other hand, the sodium borohydride can reduce hexavalent chromium to trivalent chromium or even elemental chromium, thereby reducing the toxicity of chromium. Simultaneously, these nano-silica particles that capture chromium can further react with the calcium hydroxide produced during the hydration of the silicate cement to form hydrated calcium silicate. After solidification, this cementitious product can fix the complexed chromium within, preventing its dissolution. This makes the thermal insulation cement-based material of the present invention more suitable for constructing aquaculture ponds, reducing its impact on water quality. Furthermore, the hydrated calcium silicate formed in the above process increases the content of the cementitious product in the thermal insulation cement-based material of the present invention, which helps to improve the mechanical strength of the mortar material. Attached Figure Description

[0023] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0024] Figure 1 The image shows a sample of the modified thermal insulation aggregate prepared in Example 1 below.

[0025] Figure 2 The image shows a sample of the chromium-reducing admixture prepared in Example 1 below.

[0026] Figure 3 The following is a diagram showing the compressive strength test results for Example 1.

[0027] Figure 4 The image shows a sample of the modified thermal insulation aggregate prepared in Example 2 below.

[0028] Figure 5 The image shows a sample of the chromium-reducing additive prepared in Example 2 below.

[0029] Figure 6 The following is a diagram showing the compressive strength test results for Example 2.

[0030] Figure 7 The image shows a sample of the chromium-reducing additive prepared in Example 3 below.

[0031] Figure 8 The following is a diagram showing the compressive strength test results for Example 3.

[0032] Figure 9 The following is a diagram showing the compressive strength test results for Example 4. Detailed Implementation

[0033] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer.

[0034] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as those skilled in the art. The reagents or raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they are used in accordance with conventional methods or product instructions. Furthermore, any methods and materials similar to or equivalent to those described herein can be applied to the methods of this invention. The technical solution of this invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0035] Example 1

[0036] A method for preparing a lightweight thermal insulation cement-based material for aquaculture includes the following steps:

[0037] (1) Expanded vermiculite particles with a particle size distribution between 2 and 6 mm were added to a 1.5 mol / L sodium hydroxide solution and stirred until homogeneous. The ratio of the two was 1 g: 30 ml. Then, the solution was heated to 75°C and kept at that temperature for 4 hours. After completion, the expanded vermiculite particles were filtered out, washed with clean water, and dried to obtain modified thermal insulation aggregate (e.g., Figure 1 (As shown), for later use.

[0038] (2) Add nano-silica to water and sonicate for 10 min to form a dispersion. Then add 0.5% (by weight of nano-silica) of polycarboxylate superplasticizer to the dispersion and stir until homogeneous. Then add twice the weight of nano-silica of sodium borohydride powder and stir until homogeneous. Then heat the resulting mixture to 80°C and keep it at that temperature until the water evaporates. Then disperse the product to obtain a chromium-reducing additive (such as...). Figure 2 (As shown), for later use.

[0039] (3) Weigh each raw material according to the following proportions: 225 parts by weight of silicate cement (P·O 42.5), 490 parts by weight of the modified thermal insulation aggregate of this embodiment, 38 parts by weight of glass microspheres, 23 parts by weight of filler (calcium carbonate powder with a fineness of 500 mesh), 0.6 parts by weight of the chromium-reducing admixture of this embodiment, 12 parts by weight of polyethylene fiber with a length of 10 mm, and 99 parts by weight of water.

[0040] (4) The silicate cement, modified thermal insulation aggregate, glass microspheres, filler and fiber are dry-mixed in a mixer for 5 minutes to obtain a mixture. Then the chromium-reducing admixture is added to water and stirred evenly, and then added to the mixture and stirred for 3 minutes to obtain the thermal insulation cement-based material.

[0041] Performance testing: 1. After preparing the thermal insulation cement-based material prepared in this embodiment into specimens, cure for 28 days, then immerse the obtained specimens in deionized water for 7 days, then test the leaching amount of chromium (VI) and calculate the chromium (VI) removal rate. (2) After preparing the thermal insulation cement-based material prepared in this embodiment into specimens, cure for 28 days, and test the compressive strength of the specimens according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GBT 50081-2019). Figure 3 (As shown). The results were: Chromium (VI) leaching amount = 0.013 mg / kg, Chromium (VI) removal rate = 99.21%, and compressive strength = 4.06 MPa.

[0042] Example 2

[0043] A method for preparing a lightweight thermal insulation cement-based material for aquaculture includes the following steps:

[0044] (1) Expanded vermiculite particles with a particle size distribution between 2 and 6 mm were added to a 3 mol / L sodium hydroxide solution and stirred until homogeneous. The ratio of the two was 1 g: 25 ml. Then, the solution was heated to 60°C and kept at that temperature for 5 hours. After completion, the expanded vermiculite particles were filtered out, washed with clean water, and dried to obtain modified thermal insulation aggregate (e.g., Figure 4 (As shown), for later use.

[0045] (2) Add nano-silica to water and sonicate for 15 min to form a dispersion. Then add 0.4% (by weight) of polycarboxylate superplasticizer to the dispersion and stir until homogeneous. Then add 1.8 times (by weight) of sodium borohydride powder to the dispersion and stir until homogeneous. Then heat the resulting mixture to 70°C and keep it at that temperature until the water evaporates. Then disperse the product to obtain a chromium-reducing additive (such as...). Figure 5 (As shown), for later use.

[0046] (3) Weigh each raw material according to the following proportions: 215 parts by weight of silicate cement (P·O 42.5), 450 parts by weight of the modified thermal insulation aggregate of this embodiment, 32 parts by weight of glass microspheres, 20 parts by weight of filler (quartz powder with a fineness of 300 mesh), 0.4 parts by weight of the chromium-reducing admixture of this embodiment, 15 parts by weight of polyethylene fiber with a length of 5 mm, and 90.3 parts by weight of water.

[0047] (4) The silicate cement, modified thermal insulation aggregate, glass microspheres, filler and fiber are dry-mixed in a mixer for 5 minutes to obtain a mixture. Then the chromium-reducing admixture is added to water and stirred evenly, and then added to the mixture and stirred for 3 minutes to obtain the thermal insulation cement-based material.

[0048] Performance testing: 1. After preparing the thermal insulation cement-based material prepared in this embodiment into specimens, cure for 28 days, then immerse the obtained specimens in deionized water for 7 days, then test the leaching amount of chromium (VI) and calculate the chromium (VI) removal rate. (2) After preparing the thermal insulation cement-based material prepared in this embodiment into specimens, cure for 28 days, and test the compressive strength of the specimens according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GBT 50081-2019). Figure 6 (As shown). The results were: Chromium (VI) leaching amount = 0.018 mg / kg, Chromium (VI) removal rate = 98.91%, and compressive strength = 4.32 MPa.

[0049] Example 3

[0050] A method for preparing a lightweight thermal insulation cement-based material for aquaculture includes the following steps:

[0051] (1) Expanded vermiculite particles with a particle size distribution between 2 and 6 mm were added to a 1 mol / L sodium hydroxide solution and stirred until homogeneous. The ratio of the two was 1 g: 50 ml. Then the solution was heated to 80 °C and kept at that temperature for 4.5 hours. After completion, the expanded vermiculite particles were filtered out, washed with clean water, and dried to obtain modified thermal insulation aggregate for later use.

[0052] (2) Add nano-silica to water and sonicate for 10 min to form a dispersion. Then add 0.75% by weight of polycarboxylate superplasticizer to the dispersion and stir until homogeneous. Then add 2.3 times the weight of sodium borohydride powder to the dispersion and stir until homogeneous. Then heat the resulting mixture to 90°C and keep it at that temperature until the water evaporates. Then disperse the product to obtain a chromium-reducing additive (such as...). Figure 7 (As shown), for later use.

[0053] (3) Weigh each raw material according to the following proportions: 240 parts by weight of silicate cement (P·O 42.5), 530 parts by weight of the modified thermal insulation aggregate of this embodiment, 48 parts by weight of glass microspheres, 30 parts by weight of filler (mica powder with a fineness of 450 mesh), 0.8 parts by weight of the chromium-reducing admixture of this embodiment, 10 parts by weight of polypropylene fiber with a length of 20 mm, and 115.2 parts by weight of water.

[0054] (4) The silicate cement, modified thermal insulation aggregate, glass microspheres, filler and fiber are dry-mixed in a mixer for 5 minutes to obtain a mixture. Then the chromium-reducing admixture is added to water and stirred evenly, and then added to the mixture and stirred for 3 minutes to obtain the thermal insulation cement-based material.

[0055] Performance testing: 1. After preparing the thermal insulation cement-based material prepared in this embodiment into specimens, cure for 28 days, then immerse the obtained specimens in deionized water for 7 days, then test the leaching amount of chromium (VI) and calculate the chromium (VI) removal rate. (2) After preparing the thermal insulation cement-based material prepared in this embodiment into specimens, cure for 28 days, and test the compressive strength of the specimens according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GBT 50081-2019). Figure 8 (As shown). The results were: Chromium (VI) leaching amount = 0.011 mg / kg, Chromium (VI) removal rate = 99.33%, and compressive strength = 3.83 MPa.

[0056] Example 4

[0057] A method for preparing a lightweight thermal insulation cement-based material for aquaculture includes the following steps:

[0058] (1) Add nano-silica to water and sonicate for 10 min to form a dispersion. Then add 0.5% of the mass of nano-silica polycarboxylate superplasticizer and stir evenly. Then add sodium borohydride powder twice the mass of nano-silica and stir evenly. Then heat the resulting mixture to 80°C and keep it warm until the water evaporates. Then disperse the product to obtain the chromium-reducing additive for later use.

[0059] (2) Weigh the raw materials as follows: 225 parts by weight of silicate cement (P·O 42.5), 490 parts by weight of expanded vermiculite particles (particle size distribution between 2 and 6 mm), 38 parts by weight of glass microspheres, 23 parts by weight of filler (calcium carbonate powder with a fineness of 500 mesh), 0.6 parts by weight of the chromium-reducing admixture in this embodiment, 12 parts by weight of polyethylene fiber with a length of 10 mm, and 99 parts by weight of water.

[0060] (3) The silicate cement, expanded vermiculite particles, glass microspheres, filler, and fiber are dry-mixed in a mixer for 5 minutes to obtain a mixture. Then, the chromium-reducing admixture is added to water and stirred evenly, and then added to the mixture and stirred for 3 minutes to obtain the thermal insulation cement-based material.

[0061] Performance testing: 1. After preparing the thermal insulation cement-based material prepared in this embodiment into specimens, cure for 28 days, then immerse the obtained specimens in deionized water for 7 days, then test the leaching amount of chromium (VI) and calculate the chromium (VI) removal rate. (2) After preparing the thermal insulation cement-based material prepared in this embodiment into specimens, cure for 28 days, and test the compressive strength of the specimens according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GBT 50081-2019). Figure 9 (As shown). The results were: Chromium (VI) leaching amount = 0.326 mg / kg, Chromium (VI) removal rate = 80.19%, and compressive strength = 3.41 MPa.

[0062] Example 5

[0063] A method for preparing a lightweight thermal insulation cement-based material for aquaculture includes the following steps:

[0064] (1) Expanded vermiculite particles with a particle size distribution between 2 and 6 mm were added to a 1 mol / L sodium hydroxide solution and stirred until homogeneous. The ratio of the two was 1 g: 50 ml. Then the solution was heated to 80 °C and kept at that temperature for 4.5 hours. After completion, the expanded vermiculite particles were filtered out, washed with clean water, and dried to obtain modified thermal insulation aggregate for later use.

[0065] (2) Weigh each raw material according to the following proportions: 240 parts by weight of silicate cement (P·O 42.5), 530 parts by weight of the modified thermal insulation aggregate of this embodiment, 48 parts by weight of glass microspheres, 30 parts by weight of filler (mica powder with a fineness of 450 mesh), 0.8 parts by weight of nano silica, 10 parts by weight of polypropylene fiber with a length of 20 mm, and 115.2 parts by weight of water.

[0066] (3) The silicate cement, modified thermal insulation aggregate, glass microspheres, filler, and fiber are dry-mixed in a mixer for 5 minutes to obtain a mixture. Then, the nano-silica is added to water and stirred evenly, and then added to the mixture and stirred for 3 minutes to obtain the thermal insulation cement-based material.

[0067] Performance testing: 1. After preparing the thermal insulation cement-based material prepared in this embodiment into specimens, it was cured for 28 days. Then, the specimens were immersed in deionized water for 7 days. The leaching amount of chromium (VI) was then tested, and the chromium (VI) removal rate was calculated. (2) After preparing the thermal insulation cement-based material prepared in this embodiment into specimens, it was cured for 28 days. The compressive strength of the specimens was tested according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GBT 50081-2019). The results were: chromium (VI) leaching amount = 0.454 mg / kg, chromium (VI) removal rate = 72.38%, compressive strength = 3.77 MPa.

[0068] Example 6

[0069] A method for preparing a lightweight thermal insulation cement-based material for aquaculture includes the following steps:

[0070] (1) Expanded vermiculite particles with a particle size distribution between 2 and 6 mm were added to a 3 mol / L sodium hydroxide solution and stirred until homogeneous. The ratio of the two was 1 g: 25 ml. Then the solution was heated to 60 °C and kept at that temperature for 5 hours. After completion, the expanded vermiculite particles were filtered out, washed with water, and dried to obtain modified thermal insulation aggregate for later use.

[0071] (2) Add nano-silica to water and sonicate for 15 min to form a dispersion. Then add 0.4% of the mass of nano-silica and polycarboxylate superplasticizer and stir evenly. Then heat the mixture to 70°C and keep it warm until the water evaporates. Then disperse the product to obtain the chromium-reducing additive for later use.

[0072] (3) Weigh each raw material according to the following proportions: 215 parts by weight of silicate cement (P·O 42.5), 450 parts by weight of the modified thermal insulation aggregate of this embodiment, 32 parts by weight of glass microspheres, 20 parts by weight of filler (quartz powder with a fineness of 300 mesh), 0.4 parts by weight of the chromium-reducing admixture of this embodiment, 15 parts by weight of polyethylene fiber with a length of 5 mm, and 90.3 parts by weight of water.

[0073] (4) The silicate cement, modified thermal insulation aggregate, glass microspheres, filler and fiber are dry-mixed in a mixer for 5 minutes to obtain a mixture. Then the chromium-reducing admixture is added to water and stirred evenly, and then added to the mixture and stirred for 3 minutes to obtain the thermal insulation cement-based material.

[0074] Performance testing: 1. After preparing the thermal insulation cement-based material prepared in this embodiment into specimens, it was cured for 28 days. Then, the specimens were immersed in deionized water for 7 days. The leaching amount of chromium (VI) was then tested, and the chromium (VI) removal rate was calculated. (2) After preparing the thermal insulation cement-based material prepared in this embodiment into specimens, it was cured for 28 days. The compressive strength of the specimens was tested according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GBT 50081-2019). The results were: chromium (VI) leaching amount = 0.641 mg / kg, chromium (VI) removal rate = 61.07%, compressive strength = 4.46 MPa.

[0075] Example 7

[0076] A method for preparing a lightweight thermal insulation cement-based material for aquaculture includes the following steps:

[0077] (1) Expanded vermiculite particles with a particle size distribution between 2 and 6 mm were added to a 1 mol / L sodium hydroxide solution and stirred until homogeneous. The ratio of the two was 1 g: 50 ml. Then the solution was heated to 80 °C and kept at that temperature for 4.5 hours. After completion, the expanded vermiculite particles were filtered out, washed with clean water, and dried to obtain modified thermal insulation aggregate for later use.

[0078] (2) Add nano-silica to water and sonicate for 10 min to form a dispersion. Then add sodium borohydride powder with a mass of 2.3 times that of nano-silica and stir evenly. Then heat the mixture to 90°C and keep it warm until the water evaporates. Then disperse the product to obtain the chromium-reducing additive for later use.

[0079] (3) Weigh each raw material according to the following proportions: 240 parts by weight of silicate cement (P·O 42.5), 530 parts by weight of the modified thermal insulation aggregate of this embodiment, 48 parts by weight of glass microspheres, 30 parts by weight of filler (mica powder with a fineness of 450 mesh), 0.8 parts by weight of the chromium-reducing admixture of this embodiment, 10 parts by weight of polypropylene fiber with a length of 20 mm, and 115.2 parts by weight of water.

[0080] (4) The silicate cement, modified thermal insulation aggregate, glass microspheres, filler and fiber are dry-mixed in a mixer for 5 minutes to obtain a mixture. Then the chromium-reducing admixture is added to water and stirred evenly, and then added to the mixture and stirred for 3 minutes to obtain the thermal insulation cement-based material.

[0081] Performance testing: 1. After preparing the thermal insulation cement-based material prepared in this embodiment into specimens, it was cured for 28 days. Then, the specimens were immersed in deionized water for 7 days. The leaching amount of chromium (VI) was then tested, and the chromium (VI) removal rate was calculated. (2) After preparing the thermal insulation cement-based material prepared in this embodiment into specimens, it was cured for 28 days. The compressive strength of the specimens was tested according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GBT 50081-2019). The results were: chromium (VI) leaching amount = 0.272 mg / kg, chromium (VI) removal rate = 83.47%, compressive strength = 3.62 MPa.

[0082] 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 foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing lightweight thermal insulation cement-based materials for aquaculture, characterized in that, Includes the following steps: (1) Place the expanded vermiculite particles in an alkaline solution and keep them warm under heating conditions; after completion, wash the obtained expanded vermiculite particles, dry them and obtain modified thermal insulation aggregate for later use; (2) Disperse nano-silica in water to form a dispersion, then add polycarboxylate superplasticizer and stir evenly, then add sodium borohydride and stir evenly and let stand; after completion, dry to remove excess water, grind to obtain chromium-reducing additive, and set aside; (3) Take the following raw materials: silicate cement, the modified thermal insulation aggregate, glass microspheres, filler, the chromium-reducing admixture, and fiber; mix the above raw materials evenly and add water to stir evenly to obtain the thermal insulation cement-based material.

2. The method for preparing lightweight thermal insulation cement-based materials for aquaculture according to claim 1, characterized in that, In step (1), the ratio of expanded vermiculite particles to alkaline solution is 1g: 25~50ml.

3. The method for preparing lightweight thermal insulation cement-based materials for aquaculture according to claim 1, characterized in that, The expanded vermiculite particles have a particle size of 2-6 mm.

4. The method for preparing lightweight thermal insulation cement-based materials for aquaculture according to claim 1, characterized in that, In step (1), the concentration of the alkaline solution is 1~3 mol / L.

5. The method for preparing lightweight thermal insulation cement-based materials for aquaculture according to claim 1, characterized in that, In step (1), the alkaline solution includes at least one of sodium hydroxide solution and potassium hydroxide solution.

6. The method for preparing lightweight thermal insulation cement-based materials for aquaculture according to claim 1, characterized in that, In step (1), the heating temperature is 60~80℃ and the heat preservation time is 4~5 hours.

7. The method for preparing lightweight thermal insulation cement-based materials for aquaculture according to claim 1, characterized in that, In step (2), the polycarboxylate superplasticizer is 0.4 to 0.75% of the mass of nano-silica.

8. The method for preparing lightweight thermal insulation cement-based materials for aquaculture according to claim 1, characterized in that, In step (2), the mass ratio of sodium borohydride to nano-silica is 1.8~2.3:

1.

9. The method for preparing lightweight thermal insulation cement-based materials for aquaculture according to claim 1, characterized in that, In step (2), the drying method includes at least one of heating and freeze drying.

10. The method for preparing lightweight thermal insulation cement-based materials for aquaculture according to claim 9, characterized in that, The heating temperature is 70~90℃.

11. The method for preparing lightweight thermal insulation cement-based materials for aquaculture according to any one of claims 1-10, characterized in that, In step (3), the proportions of each component in the raw materials are as follows: 215-240 parts by weight of silicate cement, 450-530 parts by weight of the modified thermal insulation aggregate, 32-48 parts by weight of glass microspheres, 20-30 parts by weight of filler, 0.4-0.8 parts by weight of the chromium-reducing admixture, and 10-15 parts by weight of fiber.

12. The method for preparing lightweight thermal insulation cement-based materials for aquaculture according to any one of claims 1-10, characterized in that, In step (3), water is added at a water-cement ratio of 0.42 to 0.

48.

13. The method for preparing lightweight thermal insulation cement-based materials for aquaculture according to any one of claims 1-10, characterized in that, In step (3), the filler includes at least one of calcium carbonate powder, mica powder, and quartz powder.

14. The method for preparing lightweight thermal insulation cement-based materials for aquaculture according to any one of claims 1-10, characterized in that, The filler has a fineness of 300-500 mesh.

15. The method for preparing lightweight thermal insulation cement-based materials for aquaculture according to any one of claims 1-10, characterized in that, In step (3), the fiber includes at least one of polyethylene fiber, polypropylene fiber, polyacrylonitrile fiber, and basalt fiber.

16. The method for preparing lightweight thermal insulation cement-based materials for aquaculture according to any one of claims 1-10, characterized in that, In step (3), the length of the fiber is 5~20mm.

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