Bionic flame-retardant high-toughness cement-based material and preparation method thereof

Abstract

The invention discloses a bionic flame-retardant high-toughness cement-based material and a preparation method thereof. The cement-based material is composed of a flame-retardant layer and a high-toughness layer. Wherein the flame-retardant layer comprises cement, a fire-resistant filler and a fluxing agent; the high-toughness layer is formed by arranging a plurality of layers of MDF sheets layer by layer in a gradient mode and then conducting hot pressing. According to the method, a deep-sea volcanic vent snail imitating structure is formed by adding the refractory filler and the fluxing agent, adjusting the content of silicon and aluminum in cement and adjusting the process, operation is easy, cost is controllable, implementation is easy, the high toughness of the cement-based composite material is improved, meanwhile, the problem that toughness is reduced due to strength improvement is solved, and the service life of the cement-based composite material is prolonged. And the fire-resistant and flame-retardant effects of the cement-based material are also improved, and the flame-retardant and high-toughness cement-based material can cover a wider application range.

Description

Technical Field

[0001] The invention relates to an aluminate cement-based material and a preparation method thereof, in particular to a composite bionic flame-retardant high-strength and tough aluminate cement-based material and a preparation method thereof, belonging to the field of civil engineering and building materials. Background Art

[0002] As a non-idealized uniform composite material, cement-based composite materials have inherent quasi-brittleness, low bending strength and tensile strength, poor toughness and brittle cracking. These inherent shortcomings greatly restrict the scope of application of cement-based materials. Existing toughening measures include toughening with steel bars, toughening with nanomaterials, toughening with fibers and toughening with polymers, but all have limited improvement effects and are insufficient, making it difficult to meet the demand for improved strength and toughness. At the same time, under high temperature conditions, cement-based materials cannot play a good flame retardant role. When subjected to high temperature shock, they will quickly break and affect their use, limiting their application scenarios.

[0003] In recent years, bionic technology has been developing continuously in the field of materials science, and the application of bionic concepts to the research of cement-based materials has also made some progress. Domestic and foreign scholars have selected natural biological materials as bionic objects and conducted a series of studies. However, at present, there is still a lack of a bionic flame-retardant high-strength and tough cement-based material that can be used in extreme environments of high temperature, high pressure and high impact. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to provide a bionic flame retardant high-strength and tough cement-based material that can be used in extreme environments of high temperature, high pressure and high impact; another purpose of the present invention is to provide a method for preparing a bionic flame retardant high-strength and tough cement-based material.

[0005] Technical solution: The present invention provides a bionic flame-retardant high-strength and tough cement-based material, which is formed by hot pressing a flame-retardant layer and at least one high-strength and tough layer; wherein the flame-retardant layer comprises cement, refractory filler and flux; and the high-strength and tough layer is formed by hot pressing a plurality of layers of MDF sheets which are arranged in a gradient manner layer by layer.

[0006] In the above technical solution, the high-strength and toughness layer in the cement-based material can be a single layer or N layers; a group of MDF (macro-defect-free) sheets arranged in a gradient layer by layer constitutes a single layer of high-strength and toughness layer, and the MDF sheets arranged in a gradient layer by layer are repeated N times to constitute N layers of high-strength and toughness layers. Where N is greater than 1.

[0007] Furthermore, the components of the flame retardant layer include, by weight, 500 parts of cement, 15 parts of PVA, 0-50 parts of mica powder, 0-50 parts of montmorillonite, 0-50 parts of zinc borate, and 0-50 parts of ammonium polyphosphate.

[0008] Further, the components of the flame retardant layer include, by weight, 500 parts of cement, 15 parts of PVA, 10 - 50 parts of mica powder, 10 - 50 parts of montmorillonite, 10 - 50 parts of zinc borate, and 10 - 50 parts of ammonium polyphosphate.

[0009] Further, the components of the MDF sheet include, by weight, 500 parts of cement, 60 parts of water, and 0 - 35 parts of PVA.

[0010] Further, the farther the MDF sheet is from the flame retardant layer, the greater its thickness.

[0011] On the other hand, the present invention provides a method for preparing the above - mentioned bionic flame - retardant high - strength and high - toughness cement - based material, which is characterized in that the cement - based material is formed by hot - pressing a flame retardant layer and a high - strength and high - toughness layer;

[0012] The preparation method of the flame retardant layer is as follows:

[0013] (1) After the dry materials of the flame retardant layer are stirred evenly, water is added, and after stirring evenly again, a semi - dry cement mixture is obtained.

[0014] (2) The above - mentioned semi - dry cement mixture is evenly spread in a mold and hot - pressed into shape;

[0015] (3) Hot - press molding and taking out the finished product for curing, and the flame retardant layer is obtained after curing is completed;

[0016] The preparation method of the high - strength and high - toughness layer is as follows:

[0017] (1) After the dry materials of the high - strength and high - toughness layer are stirred evenly, water is added, and after stirring evenly again, a semi - dry cement mixture is obtained.

[0018] (2) According to the gradient thickness, the above - mentioned semi - dry cement mixture is made into several MDF plastic sheets with different thicknesses; they are arranged layer by layer according to the thickness; and then hot - pressed into shape;

[0019] (3) Hot - press molding and taking out the finished product for curing, and the high - strength and high - toughness layer is obtained after curing is completed.

[0020] Further, after the high - strength and high - toughness layer is laid flat above the flame retardant layer, hot - press molding is carried out to obtain the bionic flame - retardant high - strength and high - toughness cement - based material.

[0021] Further, in the preparation of the flame retardant layer and / or the high - strength and high - toughness layer, a hot - press machine is used for hot - press molding.

[0022] Further, in the preparation of the flame retardant layer and / or the high - strength and high - toughness layer, the temperature of hot - press molding is 80 - 90 °C.

[0023] Further, in the preparation of the flame retardant layer and / or the high - strength and high - toughness layer, the temperature of curing is 70 - 80 °C.

[0024] Beneficial effects: Compared with the prior art, the present invention has the following remarkable advantages: (1) The present invention uses a multi-layer structure to simulate the structure of deep-sea hydrothermal vent snails. By adding refractory fillers and fluxes, it plays a flame-retardant role, and the optimized arrangement of MDF sheets plays a high-strength and toughness-enhancing role. It not only ensures the high strength of the cement-based composite material, solves the problem of reduced toughness caused by strength improvement, but also improves the fire resistance and flame retardancy of the cement-based material.

[0025] (2) This method uses hot pressing to rapidly form the strength of aluminate cement. While the mold is rapidly recycled, the cycle from processing and forming to use is also significantly shortened.

[0026] (3) The method for enhancing the bionic flame retardancy, strength and toughness of the aluminate cement-based material provided by the present invention has a small number of raw materials, a simple mixing ratio, simple operation, controllable cost and is easy to implement. Description of the Drawings

[0027] Figure 1 Shows the flame retardant effects of different mixing ratios in Example 1;

[0028] Figure 2 Shows the strength and toughness effects of different silicon-aluminum contents and preparation processes in Example 2. Detailed Embodiments

[0029] The following embodiments are intended to further illustrate the present invention, but should not be construed as limiting the protection scope of the present invention. Further non-substantive improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the protection scope of the present invention.

[0030] Design concept of the present invention: By exploring organisms in nature, the applicant found the "deep-sea hydrothermal vent snail" as the bionic object. They mainly inhabit the hydrothermal vent areas on the deep-sea floor of the Indian Ocean. These areas are extremely harsh extreme living environments with high temperature, high pressure and complete darkness. The abdomen and feet of these snails are covered with iron-containing scales, and they have an unusual three-layer iron-containing hard shell that can resist external attacks and are also known as the "iron-armored beasts in the deep sea". Their shells are divided into multiple layers. They not only have a cuticle layer that can insulate heat, but also have a very strong shock-absorbing and bonding effect inside and outside; there is also a calcium carbonate layer that provides core protection for the main body. The multi-layer structure constructs the strongest snail shell on Earth, which is both compressive and heat-insulating, ensuring that it can live at the hydrothermal vents of the deep-sea volcanic craters 2400 - 2900 meters deep. The present invention uses a multi-layer structure to simulate the structure of deep-sea hydrothermal vent snails. By adding refractory fillers and fluxes, it plays a flame-retardant role, and the optimized arrangement of MDF sheets plays a high-strength and toughness-enhancing role. It not only ensures the high strength of the cement-based composite material, solves the problem of reduced toughness caused by strength improvement, but also improves the fire resistance and flame retardancy of the cement-based material.

[0031] A bionic flame-retardant high-strength and tough aluminate cement-based material of the present invention, wherein the aluminate cement-based material is formed by hot-pressing two parts, namely a flame-retardant layer and a high-strength and tough layer. The flame-retardant layer is formed by spreading flocculent particles formed by stirring, rolling and crushing related cement, refractory fillers and fluxes in a mold. The components of the related materials include, by weight fraction, 500 parts of cement, 90 parts of water, 15 parts of PVA, 10 - 50 parts of mica powder, 10 - 50 parts of montmorillonite, 10 - 50 parts of zinc borate, and 10 - 50 parts of ammonium polyphosphate; the high-strength and tough layer is formed by hot-pressing several layers of MDF sheets arranged in a gradient. The components of each layer of the MDF sheet include, by weight fraction, 500 parts of cement, 60 parts of water, and 0 - 35 parts of PVA.

[0032] Taking four layers of MDF sheets as an example, the gradient arrangement structure includes an MDF sheet with a thickness of a as layer a, a layer paved on layer a which is an MDF sheet with a thickness of b to form layer b, a layer paved on layer b which is an MDF sheet with a thickness of c to form layer c, and a layer paved on layer c which is an MDF sheet with a thickness of d to form layer d.

[0033] Preferably, the thickness of layer d > the thickness of layer c > the thickness of layer b > the thickness of layer a.

[0034] Preferably, the PVA powder is 200 mesh and the alcoholysis degree is 88%.

[0035] Example 1:

[0036] A preparation method of a bionic flame-retardant high-strength and tough cement-based material includes the following steps:

[0037] (1) First, add the powder materials shown in Table 1 into a 3L container and stir with a whisk. Stir at low speed for 60s first, then add 90g of water and stir at high speed for 120s to obtain a semi-dry cement mixture. Spread the above mixture at the bottom inside the mold, and the preparation of the flame-retardant layer is completed;

[0038] Table 1 Research on the mixing ratio for improving the flame-retardant performance of an aluminate cement-based material

[0039]

[0040] (2) Then, take 500g of cement and 35g of PVA and put them into a 3L container. Stir with a whisk, stir at low speed for 60s first, then add 90g of water and stir at high speed for 120s to obtain a semi-dry cement mixture.

[0041] (3) Add the semi-dry cement mixture in step (2) above into a roller for rolling. The rolling thickness condition is within 1.5 mm. After rolling for about 180 s, a complete plastic sheet is obtained. After cutting the above plastic sheet according to the size of the mold, evenly spread it on top of the flame retardant layer. Use a hot press to maintain a hot press at 15 MPa for 20 min at a temperature of 80 °C.

[0042] (4) Take out the specimen after hot pressing, put the specimen into an oven for curing. The curing temperature is 80 °C and the curing duration is 3 d. After curing is completed, simulate high-temperature impact through a spray gun to test its flame retardant performance.

[0043] (5) The flame retardant performances of specimens with different mix ratios are as Figure 1 shown. In a bionic flame retardant high-strength and tough cement-based material, the optimal mix ratio of the components of the flame retardant layer is 500 g of cement, 90 g of water, 15 g of PVA, 10 g of mica powder, 10 g of montmorillonite, 10 g of zinc borate, and 10 g of ammonium polyphosphate.

[0044] Example 2:

[0045] A preparation method of a bionic flame retardant high-strength and tough cement-based material, comprising the following steps:

[0046] (1) Add the powder materials of 500 g of cement, 15 g of PVA, 10 g of mica powder, 10 g of montmorillonite, 10 g of zinc borate, and 10 g of ammonium polyphosphate into a 3 L container, stir with a whisk, first stir at a low speed for 60 s, then add 90 g of water and stir at a high speed for 120 s to obtain a semi-dry cement mixture. Spread the above mixture under the inside of the mold, thus completing the preparation of the flame retardant layer;

[0047] (2) Put the cements with different silicon-aluminum contents in Table 2 and 35 g of PVA into a 3 L container, stir with a whisk, first stir at a low speed for 60 s, then add 90 g of water and stir at a high speed for 120 s to obtain a semi-dry cement mixture.

[0048] (3) Add the semi-dry cement mixture in step (2) above into a roller for rolling. The rolling thickness condition is within 1.5 mm. After rolling for about 180 s, a complete plastic sheet is obtained. After treating the above plastic sheet according to the preparation process described in Table 2, evenly spread it on top of the flame retardant layer. Use a hot press to maintain a hot press at 15 MPa for 20 min at a temperature of 80 °C.

[0049] Table 2 Research on the mix ratio for improving the toughness performance of an aluminate cement-based material

[0050]

[0051]

[0052] The specific operation method of the crushing granulation process in Table 2 is as follows: Put the plastic sheet obtained in the above step (3) into a whisk and crush it into particles at high speed. Screen the particles using a sieve and a vibrating sieve, and use the codes 0, 1, 2, and 3 to represent particles with diameters of approximately 0.5 mm, 1 mm, 1.25 mm, and 2 mm respectively. Arrange them in the order of 0123 (0123 represents arranging the particles in the order of 0.5 mm, 1 mm, 1.25 mm, and 2 mm). After arranging them in the order of "0123", a single-layer high-strength and tough layer is obtained. 7Z has three layers of high-strength and tough layers.

[0053] The specific operation method of the layer-by-layer arrangement of MDF in Table 2 is as follows: Cut the plastic sheet with a thickness of 1.5 mm obtained in the above step (3) into regular sheets of the same size as the mold, and then stack the above regular sheets layer by layer in the mold. In the high-strength and tough layer of 7M, there are a total of 6 plastic sheets with a thickness of 1.5 mm. In the high-strength and tough layer of 8M, there are a total of 6 plastic sheets with a thickness of 1.5 mm.

[0054] The specific operation method of the layer-by-layer gradient arrangement of MDF in Table 2 is as follows: Perform secondary, tertiary, and quaternary rolling on the plastic with a thickness of 1.5 mm obtained in the above step (3) to obtain plastic sheets with thicknesses of 1 mm, 0.6 mm, and 0.4 mm respectively. Then cut the above sheets into regular sheets of the same size as the mold, and arrange them in the order of 0123 (for example, 0123 represents plastic sheets with thicknesses of 0.4 mm, 0.6 mm, 1 mm, and 1.5 mm) to obtain a single-layer high-strength and tough layer. 8MG has three layers of high-strength and tough layers.

[0055] (4) Take out the specimen after hot pressing, put the specimen into an oven for curing. The curing temperature is 80 °C and the curing duration is 3 d. After curing is completed, take out the specimen and cut the specimen into an appropriate size using cutting and keep the surface flat. Use a universal testing machine to test the specimen for three-point bending test and compressive test to obtain its flexural strength and compressive strength.

[0056] (5) The flexural and compressive strengths of the test blocks prepared with different silicon-aluminum contents and preparation processes are as Figure 2 shown. The flexural strength of the test block made by the granulation process using cement with a lower aluminum content is 64.83 MPa, and the toughness is 268.87 kJ / m 3。However, by using the MDF process, the flexural strength is increased by 231.77% compared with it, and the toughness is increased by 197.37%. Further adjusting the silicon-aluminum content and improving the process to the MDF gradient process, the flexural strength is increased by 305.92%, and the toughness is increased by 265.14%. Compared with 8M, the flexural strength of 8MG is increased by 109.43%, and the toughness is increased by 126.10%. In a bionic flame-retardant high-strength and high-toughness cement-based material, the best cement type and preparation process for the high-strength and high-toughness layer are 500 g of CA80 aluminate cement, 90 g of water, 35 g of PVA, and arranged in a MDF layer-by-layer gradient.

Claims

1. A bionic flame-retardant high-strength cement-based material, characterized in that: The cement-based material is formed by hot pressing a flame retardant layer and a high-strength and toughness layer; wherein the flame retardant layer comprises cement, refractory filler and flux; and the high-strength and toughness layer is formed by hot pressing a plurality of layers of MDF sheets which are arranged in a gradient manner layer by layer.

2. The bionic flame-retardant high-strength cement-based material according to claim 1, characterized in that: The components of the flame retardant layer include, by weight, 500 parts of cement, 15 parts of PVA, 0-50 parts of mica powder, 0-50 parts of montmorillonite, 0-50 parts of zinc borate, and 0-50 parts of ammonium polyphosphate.

3. The bionic flame-retardant high-strength cement-based material according to claim 1, characterized in that: The components of the flame retardant layer include, by weight, 500 parts of cement, 15 parts of PVA, 10-50 parts of mica powder, 10-50 parts of montmorillonite, 10-50 parts of zinc borate, and 10-50 parts of ammonium polyphosphate.

4. The bionic flame-retardant high-strength cement-based material according to claim 1, characterized in that: The components of the MDF sheet include, by weight, 500 parts of cement, 60 parts of water, and 0-35 parts of PVA.

5. The bionic flame-retardant high-strength cement-based material according to claim 1, characterized in that: The further away the MDF sheet is from the flame retardant layer, the greater its thickness.

6. A method for preparing the bionic flame-retardant high-strength cement-based material according to any one of claims 1 to 5, characterized in that: The cement-based material is formed by hot pressing a flame retardant layer and a high-strength and tough layer; The preparation method of the flame retardant layer is as follows: (1) After the dry material of the flame retardant layer is stirred evenly, water is added and stirred evenly again to obtain a semi-dry cement mixture. (2) evenly spreading the semi-dry cement mixture in a mold for hot pressing; (3) hot pressing and taking out the finished product for curing, and obtaining the flame retardant layer after the curing is completed; The preparation method of the high-strength and toughness layer is as follows: (1) After the dry materials of the high-strength and toughness layer are stirred evenly, water is added and stirred evenly again to obtain a semi-dry cement mixture. (2) According to the gradient thickness, the semi-dry cement mixture is made into a plurality of MDF plastic sheets of different thicknesses; the sheets are arranged layer by layer according to the thickness; and hot-pressed; (3) Hot pressing and taking out the finished product for curing, after which a high-strength and toughness layer is obtained.

7. The method for preparing the bionic flame-retardant high-strength cement-based material according to claim 1, characterized in that: The high-strength and toughness layer is laid flat on the flame-retardant layer and then hot-pressed to obtain a bionic flame-retardant high-strength and toughness cement-based material.

8. The method for preparing the bionic flame-retardant high-strength cement-based material according to claim 1, characterized in that: In the preparation of the flame retardant layer and / or the high-toughness layer, a hot press is used for hot pressing molding.

9. The method for preparing the bionic flame-retardant high-strength cement-based material according to claim 1, characterized in that: In the preparation of the flame retardant layer and / or the high-strength and toughness layer, the temperature of hot pressing is 80-90°C.

10. The method for preparing the bionic flame-retardant high-strength cement-based material according to claim 1, characterized in that: In the preparation of the flame retardant layer and / or the high-strength and tough layer, the curing temperature is 70-80°C.

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