Shielding cement material

Abstract

The invention relates to the technical field of cement, and particularly discloses a shielding cement material. The shielding cement material comprises a component A and a component B. The component A comprises Portland cement, zeolite, fly ash, gravel and quartz sand, and the component B comprises a graphene-nano-silver compound, a silane coupling agent and water. The graphene-nano-silver compound is prepared by the following steps: adding graphene and nano-silver into an N-methyl pyrrolidone solution, stirring, carrying out ultrasonic dispersion, and then drying to obtain the graphene-nano-silver compound. The highest shielding effects of the shielding cement material at 100 MHz, 300 MHz, 500 MHz and 1 GHz are 25.8 dB, 36.2 dB, 46.5 dB and 65.9 dB respectively, and the shielding effect of the shielding cement material is improved. Moreover, the flexural strength reaches up to 16.3 MPa, the low water absorption rate and porosity are kept, the surface is free of peeling and cracking phenomena after 50 times of freezing and thawing cycles, and the excellent comprehensive performance is achieved.

Description

Technical Field

[0001] The present application relates to the field of cement, and more particularly, to a shielding cement material. Background Art

[0002] With the rapid development of wireless communication technology, the electromagnetic environment is becoming increasingly complex, and electromagnetic interference and radiation issues are becoming increasingly severe. Shielding cement, also known as radiation-proof cement or protective cement, is a specialty cement with radiation shielding capabilities. It is primarily used in locations requiring radiation shielding, such as nuclear industrial facilities and hospital radiology departments. It prevents the leakage of electronic information within buildings while also reducing environmental pollution from external electromagnetic radiation sources to those inside, thereby ensuring electronic information security and the health of personnel. Currently, while shielding cement has some shielding effectiveness, the effectiveness is suboptimal and cannot meet practical application requirements.

[0003] In related technologies, in order to improve the shielding effect of shielding cement materials, metal materials such as iron powder and copper powder are added to the cement raw materials. The good conductivity of the metal is used to reflect electromagnetic waves, thereby improving the shielding effect. However, the addition of a large amount of metal materials will increase the density of the cement, causing the shielding cement material to become heavier, which is not conducive to construction and use. In addition, the metal has corroded and the shielding effect cannot be guaranteed for a long time. Summary of the Invention

[0004] In order to improve the shielding effect of the shielding cement material, the present application provides a shielding cement material.

[0005] In a first aspect, the present application provides a shielding cement material, which adopts the following technical solution: A shielding cement material, comprising component A and component B; based on the total mass of the shielding cement material, component A comprises the following raw materials in parts by weight: 50-70 parts of Portland cement, 3-5 parts of zeolite, 5-15 parts of fly ash, 5-10 parts of crushed stone, and 5-10 parts of quartz sand; and component B comprises the following raw materials in parts by weight: 5-10 parts of a graphene-nanosilver composite, 1-3 parts of a silane coupling agent, and 90-100 parts of water; The graphene-nanosilver composite is prepared by the following steps: adding graphene and nanosilver to N-methylpyrrolidone, stirring at 600-800 rpm for 2-4 hours, ultrasonically dispersing at 200-500W for 30-60 minutes, and drying to obtain the graphene-nanosilver composite; the amount of the graphene used is 1-2% by volume of the N-methylpyrrolidone.

[0006] By adopting the above-mentioned technical solution, a graphene-nanosilver composite is added to the shielding cement material. Graphene has extremely high electrical conductivity and a unique two-dimensional sheet structure, which easily forms a continuous conductive network in the shielding cement material. The π-π conjugation between the graphene sheets reduces electron transmission resistance, consumes electromagnetic energy, reduces interruptions in the conductive pathway, and further enhances the continuity of the network, thereby improving the shielding effectiveness of the shielding cement material. Nanosilver has extremely high electrical conductivity. When electromagnetic waves are incident on the surface of the silver powder particles, the free electrons oscillate in the electromagnetic field, forming a surface current. This converts the electromagnetic energy into heat through ohmic loss, while also generating strong specular reflection, reducing the transmission of electromagnetic waves, thereby improving the shielding effectiveness of the shielding cement material.

[0007] Graphene and nanosilver are added to an N-methylpyrrolidone solution, dispersed, and then dried to form a graphene-nanosilver composite, forming a three-dimensional conductive network of "particles and sheets" interwoven together. This not only improves the conductivity of the nanosilver, but also reduces network defects through the extensibility of the graphene sheets, lowering the percolation threshold and further enhancing the shielding effect of the shielding cement material. On the other hand, the dielectric constant of metallic silver nanosilver is low, and direct compounding can easily lead to interfacial impedance mismatch, causing excessive reflection of electromagnetic waves on the surface and making it difficult for them to enter the interior of the material. When used in conjunction with graphene, graphene can promote electromagnetic waves to enter the interior and improve the shielding effect of the nanosilver. It also makes up for the problem of insufficient dispersion of graphene, allowing the graphene sheet structure to cover the nanosilver, reducing nanosilver agglomeration, thereby ensuring the shielding effect of the shielding cement material.

[0008] Preferably, a shielding cement material comprises, based on the total mass of the shielding cement material, component A comprising the following raw materials in parts by weight: 55-65 parts of Portland cement, 3.5-4.5 parts of zeolite, 8-12 parts of fly ash, 7-9 parts of crushed stone, and 7-9 parts of quartz sand; and component B comprising the following raw materials in parts by weight: 7-9 parts of graphene-nanosilver composite, 1.5-2.5 parts of silane coupling agent, and 93-97 parts of water.

[0009] Component A of the shielding cement material of this application comprises 55-65 parts of silicate cement, 3.5-4.5 parts of zeolite, 8-12 parts of fly ash, 7-9 parts of crushed stone, and 7-9 parts of quartz sand; component B comprises 7-9 parts of graphene-nanosilver composite, 1.5-2.5 parts of silane coupling agent, and 93-97 parts of water. The performance of the shielding cement materials is predictable and they all have a high shielding effect.

[0010] Preferably, the mass ratio of the nanosilver to the graphene is 1:(1-3).

[0011] By adopting the above scheme and adjusting the mass ratio of nanosilver to graphene, the synergistic effect of nanosilver and graphene can be further improved, thereby further enhancing the shielding effect of the shielding cement material.

[0012] Preferably, the nanosilver is pretreated and then added to an N-methylpyrrolidone solution with graphene, specifically: S1, dissolving polyvinylpyrrolidone in deionized water, stirring at 40-60° C., and adjusting the pH to 7-9 to obtain a polyvinylpyrrolidone solution; S2. Add the nanosilver to the polyvinyl pyrrolidone solution, stir at a constant speed of 500-700 rpm, ultrasonically disperse at 200-400 W for 15-30 min, react with stirring for 1-3 h, filter and wash, and vacuum dry at 40-60° C. for 4-5 h to obtain the pretreated nanosilver.

[0013] Wherein, the mass concentration of the polyvinyl pyrrolidone solution is 50-60g / L.

[0014] By adopting the above scheme, polyvinyl pyrrolidone is coated on the surface of nanosilver, so that the nanosilver is evenly dispersed in the graphene, reducing the shielding weak points caused by agglomeration, thereby improving the shielding effect of the graphene-nanosilver composite.

[0015] Preferably, the mass ratio of the polyvinyl pyrrolidone to the nanosilver is 1:(20-40).

[0016] By adopting the above scheme, the mass ratio of polyvinyl pyrrolidone to nanosilver is adjusted, the coating effect of polyvinyl pyrrolidone on the surface of nanosilver is improved, and the shielding effect of the graphene-nanosilver composite is further improved.

[0017] Preferably, the shielding cement material further comprises hollow glass microspheres.

[0018] By adopting the above solution, the hollow glass microspheres are hollow spheres with smooth surfaces and air cavities inside. When electromagnetic waves are incident, the surface of the spheres produces mirror reflection. However, the electromagnetic waves entering the internal cavity are reflected and refracted multiple times at the air-glass interface, forming "cavity loss" and extending the energy dissipation path. The hollow glass microspheres also promote the reflection and scattering of electromagnetic waves, reducing the direct penetration channels of electromagnetic waves. In addition, the hollow glass microspheres can inhibit the agglomeration of the graphene-nanosilver composite, further improving the shielding effect of the graphene-nanosilver composite.

[0019] Preferably, the weight ratio of the hollow glass microspheres to the graphene-nanosilver composite is 1:(2-4).

[0020] By adopting the above scheme, the weight ratio of the hollow glass microspheres and the graphene-nanosilver composite is controlled, which is more conducive to the hollow glass microspheres and the graphene-nanosilver composite to synergistically enhance the shielding effect of the shielding cement material.

[0021] Preferably, the shielding cement material further comprises 0.3-0.5 parts of nickel fiber.

[0022] By adopting this solution, the addition of nickel fibers enhances electrical conductivity and corrosion resistance. The highly conductive surface creates a mirror-like reflection, directly reducing the penetration of electromagnetic waves. Furthermore, the free electrons on the nickel fiber surface are excited by the electromagnetic field, generating an induced current that converts electromagnetic energy into heat through ohmic loss, further enhancing the shielding effectiveness of the shielding cement.

[0023] In summary, this application includes at least one of the following beneficial technical effects: 1. This application controls the types and dosages of the raw materials of the shielding cement material so that the shielding effects of the shielding cement material at 100MHz, 300MHz, 500MHz, and 1GHz are 22.3dB, 32.3dB, 40.6dB, and 60.8dB, respectively, thereby improving the shielding effect of the shielding cement material.

[0024] 2. This application pre-treats the nanosilver in the graphene-nanosilver composite and controls the raw material dosage, so that the shielding effects of the shielding cement material at 100MHz, 300MHz, 500MHz, and 1GHz are 23.5dB, 33.8dB, 43.1dB, and 63.5dB, respectively, further improving the shielding effect of the shielding cement material.

[0025] 3. This application improves the shielding effect of the shielding cement material by adjusting the mass ratio of nanosilver to graphene in the graphene-nanosilver composite so that the shielding effects of the shielding cement material at 100MHz, 300MHz, 500MHz, and 1GHz are 24.0-24.5dB, 34.2-34.8dB, 43.5-44.8dB, and 64.0-64.5dB, respectively, thereby further improving the shielding effect of the shielding cement material.

[0026] 4. This application further improves the shielding effect of the shielding cement material by adding hollow glass microspheres to component B and controlling the weight ratio of the hollow glass microspheres to the graphene-nanosilver composite, so that the shielding effects of the shielding cement material at 100MHz, 300MHz, 500MHz, and 1GHz are 25.2-25.5dB, 35.4-35.8dB, 45.4-45.9dB, and 65.2-65.5dB, respectively.

[0027] 5. By adding nickel fiber to component B, the present application makes the shielding effect of the shielding cement material at 100MHz, 300MHz, 500MHz and 1GHz 25.8dB, 36.2dB, 46.5dB and 65.9dB respectively, thereby further improving the shielding effect of the shielding cement material.

[0028] 6. On the basis of having a high shielding effect, this application has a flexural strength of up to 16.3MPa, and maintains low water absorption and porosity. In the anti-freeze performance test, after 50 freeze-thaw cycles, there is no peeling or cracking on the surface of the shielding cement material. DETAILED DESCRIPTION

[0029] The present application is further described in detail below with reference to specific examples. The following raw materials in this application are all commercially available products, and are intended to fully disclose the raw materials of this application, and should not be understood as limiting the sources of the raw materials. Specifically: Portland cement, model PSA32.5; zeolite, particle size 40 mesh; fly ash, particle size 200 mesh; quartz sand, particle size 200 mesh; silane coupling agent, model KH550; graphene, particle size 0.5-3μm; nanosilver, particle size 20nm; N-methylpyrrolidone, effective substance content 95%; polyvinylpyrrolidone, effective substance content 99%; hollow glass microspheres, specific gravity 0.38, effective substance content 99%; nickel fiber, diameter 100μm.

[0030] The following is an example of the preparation of graphene-nanosilver composite: Preparation Example 1 The graphene-nanosilver composite of Preparation Example 1 was obtained by the following steps: 15 g of graphene and 30 g of nanosilver were added to 1 L of N-methylpyrrolidone, stirred at 600 rpm for 3 h, ultrasonically dispersed at 350 W for 45 min, and dried to obtain a graphene-nanosilver composite.

[0031] Preparation Example 2 The graphene-nanosilver composite of Preparation Example 2 differs from that of Preparation Example 1 in that: the nanosilver is pretreated and then added to the N-methylpyrrolidone solution with the graphene. The remaining steps are the same as those of Preparation Example 1, specifically: S1, dissolving 50 g of polyvinylpyrrolidone in 1 L of deionized water, stirring at 40-60° C., and adjusting the pH to 7-9 to obtain a polyvinylpyrrolidone solution; S2, adding 500 g of nanosilver to the polyvinylpyrrolidone solution, stirring at a constant speed of 600 rpm, ultrasonically dispersing at 300 W for 20 min, stirring for 2 h, filtering and washing, and vacuum drying at 50° C. for 4.5 h to obtain the pretreated nanosilver.

[0032] Preparation Examples 3-6 The graphene-nanosilver composites of Preparation Examples 3-6 differ from Preparation Example 2 in that when pretreating the nanosilver, the dosage of the nanosilver is 1000 g, 1500 g, 2000 g and 2500 g, respectively. The preparation method is the same as that of Preparation Example 2.

[0033] Preparation Examples 7-10 The graphene-nanosilver composites of Preparation Examples 7-10 have the same raw material types and preparation methods as Preparation Example 4, except that the nanosilver dosage is different, specifically 15g, 7.5g, 5g and 4.28g. The other raw material types and dosages are the same as Preparation Example 4.

[0034] Example 1 The shielding cement material of Example 1 is prepared by the following steps: Component A was added layer by layer to a mold according to the dosages listed in Table 1. Component B was sprayed on after each layer of component A was added. After completion, the mold was pressed at a molding pressure of 35-40 MPa and a holding time of 10-15 minutes to obtain an electromagnetic shielding cement slab material. The material was then steam-cured at 45-75°C for 5-10 hours and dried at 60°C for 1-3 hours to obtain the shielding cement material. The graphene-nanosilver composite used was the one prepared in Preparation Example 1.

[0035] Example 2-3 The shielding cement materials of Examples 2-3 are prepared in the same manner and with the same raw materials as those of Example 1, except that the amounts of the raw materials used are different. See Table 1 for details.

[0036] Table 1 Amount of each raw material of the shielding cement material component A of Examples 1-3 (unit: kg) Table 2 Amount of each raw material of shielding cement material component B of Examples 1-3 (unit: kg) raw material Example 1 Example 2 Example 3 Graphene-nanosilver composite 1 2 3 Silane coupling agent 2 2 2 water 5 5 5 Examples 4-12 The preparation method of the shielding cement material of Examples 4-12 is the same as that of Example 2, except that the graphene-nanosilver composite is the graphene-nanosilver composite prepared in Preparation Example 2-10, and the other raw material types and dosages are the same as those in Example 2.

[0037] Examples 13-17 The preparation method of the shielding cement material of Examples 13-17 is the same as that of Example 10, except that component B in the shielding cement material also includes hollow glass microspheres, and the specific dosage of the hollow glass microspheres is 2kg, 1kg, 0.67kg, 0.5kg, and 0.4kg, respectively. The dosage of other raw materials is the same as that of Example 10.

[0038] Example 18 The preparation method of the shielding cement material of Example 18 is the same as that of Example 15, except that component B in the shielding cement material also includes nickel fiber, the specific dosage of nickel fiber is 0.4 kg, and the dosage of other raw materials is the same as that of Example 15.

[0039] Comparative Example 1 The preparation method of the shielding cement material of Comparative Example 1 is exactly the same as that of Example 1, except that the graphene-nanosilver composite in the raw material of the shielding cement material is replaced by an equal amount of untreated graphene and nanosilver mixture, the amounts of graphene and nanosilver used are 15g and 30g respectively, and the types of other raw materials are the same as those in Example 1.

[0040] Performance test (I) The following testing standards or methods were used to perform performance tests on the shielding cement materials obtained in different Examples 1-18 and Comparative Example 1. The test results are shown in Table 3.

[0041] Shielding effect: Aglient HP4291B impedance analyzer was used to scan the electromagnetic shielding transmission coefficient curve of the shielding cement material in the range of 100 MHz, 300 MHz, 500 MHz and 1 GHz to obtain the shielding efficiency data.

[0042] Table 3 Performance test results of different shielding cement materials The test results in Table 3 show that the shielding effects of the shielding cement material obtained in this application at 100MHz, 300MHz, 500MHz and 1GHz are 25.8dB, 36.2dB, 46.5dB and 65.9dB respectively, which improves the shielding effect of the shielding cement material.

[0043] Combined with the performance test data of the shielding cement materials of Examples 1-3, it was found that the shielding effects of the shielding cement material of Example 2 at 100MHz, 300MHz, 500MHz, and 1GHz were 22.3dB, 32.3dB, 40.6dB, and 60.8dB, respectively, which were higher than those of Example 1 and Example 3, indicating that the homemade graphene-nanosilver composite of the present application in the raw material of the shielding cement material can improve the shielding effect of the shielding cement material, and the dosage of Example 2 is more appropriate, which further improves the shielding effect of the shielding cement material.

[0044] Combining the performance test data of the shielding cement materials of Examples 4 and 2, it was found that the shielding effects of the shielding cement material of Example 4 at 100MHz, 300MHz, 500MHz, and 1GHz were 22.5dB, 32.7dB, 41.0dB, and 61.2dB, respectively, which were higher than those of Example 2, indicating that pretreatment of the nanosilver in the graphene-nanosilver composite can further improve the shielding effect of the shielding cement material.

[0045] Combined with the performance test data of the shielding cement materials of Examples 4 and 5-8, it was found that the shielding effects of the shielding cement material of Example 6 at 100MHz, 300MHz, 500MHz, and 1GHz were 23.5dB, 33.8dB, 43.1dB, and 63.5dB, respectively, which were higher than those of Examples 4-5 and 7-8, indicating that when the nanosilver was pretreated, the mass ratio of polyvinyl pyrrolidone to nanosilver was 1:(20-40), which could further improve the shielding effect of the shielding cement material.

[0046] Combining the performance test data of the shielding cement materials of Examples 6 and 9-12, it was found that the shielding effects of the shielding cement materials of Examples 9-11 at 100MHz, 300MHz, 500MHz, and 1GHz were 24.0-24.5dB, 34.2-34.8dB, 43.5-44.8dB, and 64.0-64.5dB, respectively, which were higher than those of Examples 6 and 12, indicating that the mass ratio of nanosilver to graphene is 1:(1-3), which can further improve the shielding effect of the shielding cement material.

[0047] Combined with the performance test data of the shielding cement materials of Examples 13-17, it was found that the shielding effects of the shielding cement materials of Examples 14-16 at 100MHz, 300MHz, 500MHz, and 1GHz were 25.2-25.5dB, 35.4-35.8dB, 45.4-45.9dB, and 65.2-65.5dB, respectively, which were higher than those of Example 13 and Example 17, indicating that adding hollow glass microspheres to component B and controlling the weight ratio of hollow glass microspheres to graphene-nanosilver composite to 1:(2-4) can further improve the shielding effect of the shielding cement material.

[0048] Combining the performance test data of the shielding cement materials of Examples 15 and 18, it was found that the shielding effects of the shielding cement material of Example 18 at 100MHz, 300MHz, 500MHz and 1GHz were 25.8dB, 36.2dB, 46.5dB and 65.9dB, respectively, which were higher than those of Example 15, indicating that the addition of nickel fiber to component B can further improve the shielding effect of the shielding cement material.

[0049] Combining the performance test data of Example 1 and Comparative Example 1, it is found that adding graphene-nanosilver composite to the raw materials of shielding cement material can improve the shielding effect of the shielding cement material.

[0050] Performance Testing (II) The following testing standards or methods were used to perform performance tests on the shielding cement materials obtained in different Examples 1-18 and Comparative Example 1. The test results are shown in Table 4.

[0051] Flexural strength: GB / T 7019-1997 "Test methods for fiber cement products" is used to test the flexural strength of shielding cement materials.

[0052] Porosity: The porosity of the shielding cement material was detected by mercury intrusion porosimetry using a PoreMaster 60 fully automatic porosity analyzer produced by Quantachrome Instruments, USA.

[0053] Water absorption rate: GB / T 7019-1997 "Test methods for fiber cement products" is used to test the water absorption rate of shielding cement materials.

[0054] Frost resistance: GB / T 7019-1997 "Test methods for fiber cement products" is used to test the frost resistance of the shielding cement material. After 50 freeze-thaw cycles, observe whether the surface of the shielding cement material is peeling or cracking.

[0055] Table 4 Performance test results of different shielding cement materials The test results in Table 4 show that the shielding cement material obtained in the present application has a flexural strength of up to 16.3 MPa and maintains low water absorption and porosity. In addition, in the frost resistance test, after 50 freeze-thaw cycles, there is no peeling or cracking on the surface of the shielding cement material.

[0056] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A shielding cement material, characterized in that: The invention comprises component A and component B; based on the total mass of the shielding cement material, component A comprises the following raw materials in parts by weight: 50-70 parts of Portland cement, 3-5 parts of zeolite, 5-15 parts of fly ash, 5-10 parts of crushed stone, and 5-10 parts of quartz sand; and component B comprises the following raw materials in parts by weight: 5-10 parts of graphene-nanosilver composite, 1-3 parts of silane coupling agent, and 90-100 parts of water; The graphene-nanosilver composite is prepared by the following steps: adding graphene and nanosilver to N-methylpyrrolidone, stirring at 600-800 rpm for 2-4 hours, ultrasonically dispersing at 200-500 W for 30-60 minutes, and drying to obtain the graphene-nanosilver composite; The amount of graphene used is 1-2% of the volume of N-methylpyrrolidone.

2. The shielding cement material according to claim 1, characterized in that: Based on the total mass of the shielding cement material, the component A includes the following raw materials in parts by weight: 55-65 parts of silicate cement, 3.5-4.5 parts of zeolite, 8-12 parts of fly ash, 7-9 parts of crushed stone, and 7-9 parts of quartz sand; the component B includes the following raw materials in parts by weight: 7-9 parts of graphene-nanosilver composite, 1.5-2.5 parts of silane coupling agent, and 93-97 parts of water.

3. The shielding cement material according to claim 1, characterized in that: The mass ratio of the nanosilver to the graphene is 1:(1-3).

4. The shielding cement material according to claim 1, characterized in that: The nanosilver is pretreated and then added to the N-methylpyrrolidone solution with graphene, specifically: S1. Dissolve polyvinyl pyrrolidone in deionized water, stir at 40-60° C., and adjust the pH to 7-9 to obtain a polyvinyl pyrrolidone solution; S2. Add the nanosilver to the polyvinyl pyrrolidone solution, stir at a constant speed of 500-700 rpm, ultrasonically disperse at 200-400 W for 15-30 min, react with stirring for 1-3 h, filter and wash, and vacuum dry at 40-60° C. for 4-5 h to obtain the pretreated nanosilver.

5. The shielding cement material according to claim 4, characterized in that: The mass ratio of the polyvinyl pyrrolidone to the nanosilver is 1:(20-40).

6. The shielding cement material according to claim 1, characterized in that: The component B also includes hollow glass microspheres.

7. The shielding cement material according to claim 6, characterized in that: The weight ratio of the hollow glass microspheres to the graphene-nanosilver composite is 1:(2-4).

8. The shielding cement material according to claim 1, characterized in that: The component B further comprises 0.3-0.5 parts of nickel fiber.

Images