An anti-blast radiation shielding concrete and a method of preparing the same

Abstract

This invention relates to a crack-resistant radiation shielding concrete and its preparation method, wherein the components of the concrete are in the following mass ratio (kg / m³). 3 The composition of the concrete mix is ​​as follows: granulated blast furnace slag powder 100-150 g, serpentine 600-700 g, cement 200-300 g, yellow sand 800-1000 g, water 200-230 g, and high-efficiency water-reducing agent 10-20 g; steel fiber volume fraction 0.2%-0.5%, boron fiber volume fraction 0.1%-0.2%; and highly dispersed carbon nanotubes mass ratio 1‰-5‰. The rational combination and equivalent substitution of these three types of fibers can effectively inhibit the crack propagation of radiation-shielded concrete at higher temperatures and effectively improve the anti-cracking performance of concrete at high temperatures. Both boron fibers and highly dispersed carbon nanotubes are effective in improving the radiation shielding performance of concrete and maintaining the integrity of the concrete structure, ensuring the radiation shielding performance of the structure at high temperatures.

Description

Technical Field

[0001] This invention belongs to the field of radiation-shielding concrete preparation technology, and specifically relates to a crack-resistant radiation shielding concrete and its preparation method. Background Technology

[0002] Nuclear power technology is a major pathway to achieving clean energy. With technological advancements, fourth-generation nuclear power technology has gradually come into the public eye, among which thorium-based reactor technology and gas-cooled reactor technology are typical examples. Taking thorium-based reactors as an example, the internal operating temperature of a typical molten salt reactor is above 600℃, while the temperature of a conventional reactor is around 300℃. Therefore, how to improve the high-temperature performance of radiation-shielding concrete has become an urgent technical problem to be solved.

[0003] Currently, radiation shielding technology for concrete primarily focuses on increasing concrete density and the content of water of crystallization. Water of crystallization is easily lost at high temperatures, leading to decreased concrete density, cracking, and a decline in the concrete's radiation shielding ability—all engineering and technical problems. Drawing on fracture toughening techniques for ordinary high-performance concrete, fiber application remains the preferred method for improving the overall performance of radiation-shielding concrete. However, currently, most engineering fibers are not heat-resistant and have limited radiation shielding capabilities. Therefore, high-performance concrete fiber reinforcement technology cannot be directly applied to high-temperature radiation-shielding concrete.

[0004] Therefore, how to provide a blast-resistant radiation shielding concrete that can be mass-produced and its preparation method to meet the needs of large-scale application in nuclear facilities is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] This invention provides a crack-resistant radiation shielding concrete and its preparation method, aiming to enhance the explosion-proof and crack-resistant performance of radiation shielding concrete at high temperatures, maintain the overall structural stability, and minimize the impact of high-temperature environment on the comprehensive performance of concrete.

[0006] To solve the above technical problems, the present invention includes the following technical solutions:

[0007] A type of explosion-resistant radiation shielding concrete, wherein the components of the concrete are in the following mass ratio (kg / m³). 3 ):

[0008] Granulated blast furnace slag powder 100-150, serpentine 600-700, cement 200-300, yellow sand 800-1000, water 200-230, high-efficiency water-reducing agent 10-20; steel fiber volume fraction 0.2%-0.5%, boron fiber volume fraction 0.1%-0.2%; highly dispersible carbon nanotube mass ratio 1‰-5‰.

[0009] Furthermore, the steel fiber is a diced steel fiber or a microfiber steel fiber, with a density of 7.80 g / cm³.3 Tensile strength ≥2000MPa.

[0010] Furthermore, the boron fiber is prepared by hydrogen reduction and obtained by chemical vapor deposition, and tungsten boron fiber is selected.

[0011] Furthermore, the highly dispersed carbon nanotubes are formed by uniformly coating the surface of carbon nanotubes with rare earth metal oxides to form a core-shell structure, resulting in a uniform and structurally stable carbon nanotube composite material.

[0012] Furthermore, the highly dispersed carbon nanotubes are prepared as follows: First, the carbon nanotubes are purified; then, rare earth metal nitrates and polyvinylpyrrolidone are completely dispersed and dissolved in ethylene glycol using ultrasound to obtain an ethylene glycol solution of nitrates; second, the carbon nanotubes are added to the rare earth metal nitrate ethylene glycol solution and subjected to a heating and reflux reaction; finally, the reaction product is washed with deionized water until neutral, and then washed with alcohol and dried to obtain highly dispersed carbon nanotubes coated with rare earth metal oxides.

[0013] A method for preparing blast-resistant radiation shielding concrete, the method comprising the following steps:

[0014] Step S1: Add cement, serpentine, yellow sand, and granulated blast furnace slag powder to the mixer and stir for 30 seconds;

[0015] Step S2: Add high-efficiency water-reducing agent and highly dispersible carbon nanotubes to water and stir until uniform;

[0016] Step S3: Pour the high-efficiency water-reducing agent and the highly dispersible carbon nanotube aqueous solution into the dry mixture and stir for 120-240 seconds;

[0017] Step S4: Add steel fiber and boron fiber in sequence, and stir until uniform.

[0018] Furthermore, the cement is P.O42.5 ordinary Portland cement, the granulated blast furnace slag powder grades include S95, S105, and S115, the yellow sand is medium sand with a fineness modulus of 2.3 to 3.0, the high-efficiency water-reducing agent is a polycarboxylate high-efficiency water-reducing agent with a water reduction rate of ≥30%, and the water is ordinary tap water.

[0019] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0020] This invention provides a crack-resistant radiation shielding concrete, wherein the components of the concrete are in the following mass ratio (kg / m³). 3 ):

[0021] Granulated blast furnace slag powder 100-150, serpentine 600-700, cement 200-300, yellow sand 800-1000, water 200-230, high-efficiency water-reducing agent 10-20; steel fiber volume fraction 0.2%-0.5%, boron fiber volume fraction 0.1%-0.2%; highly dispersible carbon nanotube mass ratio 1‰-5‰.

[0022] Steel fibers have high strength and can effectively bridge large-scale cracks, improving the overall performance of concrete. However, steel fibers have limited heat resistance (melting point 1200℃), making them prone to thermal fatigue and stress relaxation at high temperatures, especially a significant decrease in tensile strength. At high temperatures, factors such as gas expansion and aggregate-binder interface separation within the concrete accelerate crack propagation, leading to gradual concrete delamination. Therefore, steel fibers have limited resistance to bursting at high temperatures. Meanwhile, commonly used synthetic fibers in concrete at room temperature, such as PP (polypropylene) and PVA (polyvinyl alcohol) fibers, have lower melting points (190℃~240℃), and the mechanical properties of concrete decrease significantly with increasing temperature. Boron fibers, on the other hand, have tensile strengths exceeding 3000MPa and melting points above 2000℃. Their performance degradation is not significant at high temperatures, allowing them to effectively bridge cracks and reinforce concrete, preventing delamination. Boron fibers are also inert and resistant to acid and alkali corrosion. Furthermore, boron has a large neutron interception surface, effectively shielding and absorbing neutrons, making it suitable as a reinforcing material for radiation-shielded concrete to resist bursting.

[0023] The incorporation of highly dispersed carbon nanotubes into concrete, due to their small geometric size, can effectively bridge micro-cracks in the concrete, inhibiting crack deterioration in the early stages of thermal expansion or dehydration cracking. While boron fibers offer excellent performance, they are expensive. The incorporation of highly dispersed carbon nanotubes effectively replaces some boron fibers, reducing the overall preparation cost of explosion-proof radiation shielding concrete and resulting in significant economic benefits. Furthermore, the reduced amount of larger-sized fibers also improves the flowability and workability of the concrete.

[0024] The cerium oxide nanoparticles covering the surface of carbon nanotubes are rare earth element oxides. Rare earth elements have a large thermal neutron absorption cross-section. Fast neutrons generated in the reactor become thermal neutrons after transferring energy to hydrogen nuclei. These thermal neutrons are easily absorbed by cerium oxide, further enhancing the radiation shielding performance of concrete.

[0025] The rational combination and equivalent substitution of three types of fibers can effectively inhibit the crack propagation of radiation-shielding concrete at high temperatures, effectively improve the anti-cracking performance of concrete at high temperatures, and bring about an improvement in the mechanical properties of concrete. Boron fibers and highly dispersed carbon nanotubes both play an effective role in improving the radiation shielding performance of concrete and maintaining the integrity of the concrete structure, ensuring the radiation shielding performance of the structure at high temperatures. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a neutron shielding test of blast-resistant radiation shielding concrete and its preparation method according to an embodiment of the present invention. Detailed Implementation

[0027] The following detailed description, in conjunction with specific embodiments, provides a more detailed explanation of the anti-cracking radiation shielding concrete and its preparation method provided by the present invention. The advantages and features of the present invention will become clearer from the following description.

[0028] The explosion-proof radiation shielding concrete mix design proposed in this invention is as follows: (kg / m³) 3 )

[0029]

[0030] The cement is PO 42.5 ordinary Portland cement, the granulated blast furnace slag powder grades include S95, S105, and S115, the fine aggregate is medium sand with a fineness modulus of 2.3 to 3.0, the high-efficiency water-reducing agent is a polycarboxylate high-efficiency water-reducing agent with a water reduction rate of ≥30%, and the water is ordinary tap water.

[0031] The steel fibers are cut steel fibers or microfibers, with a density of 7.80 g / cm³. 3 The tensile strength is generally ≥2000MPa.

[0032] Boron fibers are generally prepared by hydrogen reduction and produced by chemical vapor deposition. They are usually tungsten-boron fibers, thus ensuring comprehensive protection against neutrons and gamma rays.

[0033] By uniformly coating rare earth metal oxides onto the surface of carbon nanotubes to form a core-shell structure, a homogeneous and structurally stable carbon nanotube composite material, namely highly dispersed carbon nanotubes, is obtained. The carbon nanotubes are uniformly coated with cerium oxide nanoparticles. The inorganic oxide cerium oxide has high hydrophilicity, effectively improving the dispersion performance of carbon nanotubes in concrete. The surface oxide also enhances the compatibility between carbon nanotubes and concrete.

[0034] The highly dispersed carbon nanotubes were prepared as follows: First, the carbon nanotubes were purified. Then, rare earth metal nitrates and polyvinylpyrrolidone were completely dispersed and dissolved in ethylene glycol using ultrasound to obtain an ethylene glycol solution of nitrates. Finally, the carbon nanotubes were added to the rare earth metal nitrate ethylene glycol solution and subjected to a reflux reaction. The reaction product was washed with deionized water until neutral, and then washed with alcohol and dried to obtain highly dispersed carbon nanotubes coated with rare earth metal oxides.

[0035] This invention also provides a method for preparing explosion-proof radiation shielding concrete, comprising the following steps:

[0036] Step 1: Add cement, serpentine, yellow sand, and granulated blast furnace slag powder to the mixer and mix for 30 seconds;

[0037] Step 2: Add the high-efficiency water-reducing agent and highly dispersible carbon nanotubes to the water and stir until homogeneous;

[0038] Step 3: Pour the high-efficiency water-reducing agent and the highly dispersible carbon nanotube aqueous solution into the dry mixture and stir for 120-240 seconds;

[0039] Step 4: Add steel fiber and boron fiber in sequence, and stir until uniform.

[0040] Example 1:

[0041] The mix proportions of ordinary explosion-resistant radiation shielding concrete are as follows: (kg / m³) 3 )

[0042]

[0043] The mechanical properties and radiation shielding performance of concrete after high-temperature damage at 600℃ are as follows:

[0044]

[0045] The mix proportions of explosion-resistant radiation shielding concrete are as follows: (kg / m³) 3 )

[0046]

[0047] The mechanical properties and radiation shielding performance of concrete after high-temperature damage at 600℃ are as follows:

[0048]

[0049] The mix proportions of explosion-resistant radiation shielding concrete are as follows: (kg / m³) 3 )

[0050]

[0051] The mechanical properties and radiation shielding performance of concrete after high-temperature damage at 600℃ are as follows:

[0052]

[0053] Note: All 28-day performance data for concrete were obtained after the specimens had undergone heat damage and cooled to room temperature in a dry, ventilated place. The heating rate was 4℃ / h, and the holding time was 2h.

[0054] refer to Figure 1 The neutron flux after concrete shielding is measured in the following ways:

[0055] The neutron shielding experiment used cylindrical concrete specimens with dimensions of φ60×80mm.

[0056] A neutron source with the same energy range as the inner surface of the molten salt reactor is generated by an electron accelerator neutron source to irradiate a concrete sample. The receiver can count the collected neutron energy, and the neutron shielding performance of the concrete can be calculated by using the ratio of the neutron flux after shielding to the neutron flux before shielding.

[0057] The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. The above embodiments only illustrate several implementations of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A type of explosion-resistant radiation-shielding concrete, characterized in that, The components of the concrete are specified in kg / m³. 3 The mass ratio is: Granulated blast furnace slag powder 100~150, serpentine 600~700, cement 200~300, yellow sand 800~1000, water 200~230, high-efficiency water-reducing agent 10~20; steel fiber volume fraction 0.2%~0.5%, boron fiber volume fraction 0.1%~0.2%; The mass ratio of highly dispersed carbon nanotubes is 1‰~5‰; The highly dispersed carbon nanotubes are formed by uniformly coating the surface of carbon nanotubes with rare earth metal oxides to form a core-shell structure, resulting in a uniform and structurally stable carbon nanotube composite material. The highly dispersed carbon nanotubes are prepared as follows: First, the carbon nanotubes are purified; then, rare earth metal nitrates and polyvinylpyrrolidone are completely dispersed and dissolved in ethylene glycol using ultrasound to obtain an ethylene glycol solution of rare earth metal nitrates; next, the carbon nanotubes are added to the ethylene glycol solution of rare earth metal nitrates and subjected to a reflux reaction; finally, the reaction product is washed with deionized water until neutral, and then washed with alcohol and dried to obtain highly dispersed carbon nanotubes coated with rare earth metal oxides.

2. The anti-cracking radiation shielding concrete according to claim 1, characterized in that, The steel fibers are diced steel fibers or microfibers, with a density of 7.80 g / cm³. 3 Tensile strength ≥2000MPa.

3. The anti-cracking radiation shielding concrete according to claim 1, characterized in that, The boron fibers are prepared by hydrogen reduction and chemical vapor deposition, and tungsten-boron fibers are selected.

4. The method for preparing explosion-resistant radiation-shielding concrete according to claim 1, characterized in that, Includes the following steps: Step S1: Add cement, serpentine, yellow sand, and granulated blast furnace slag powder to the mixer and stir for 30 seconds; Step S2: Add high-efficiency water-reducing agent and highly dispersible carbon nanotubes to water and stir until uniform; Step S3: Pour the high-efficiency water-reducing agent and the highly dispersible carbon nanotube aqueous solution into the dry mixture and stir for 120~240s; Step S4: Add steel fiber and boron fiber in sequence, and stir until uniform.

5. The preparation method according to claim 4, characterized in that, The cement is P.O42.5 ordinary Portland cement, the granulated blast furnace slag powder grades include S95, S105, and S115, the yellow sand is medium sand with a fineness modulus of 2.3~3.0, the high-efficiency water-reducing agent is a polycarboxylate high-efficiency water-reducing agent with a water reduction rate ≥30%, and the water is ordinary tap water.

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