Anti-burst radiation shielding concrete and preparation method thereof

Abstract

The invention relates to anti-burst radiation shielding concrete and a preparation method thereof. The concrete comprises the following components in percentage by mass (kg / m < 3 >): 100-150 parts of granulated blast-furnace slag powder, 600-700 parts of serpentine, 200-300 parts of cement, 800-1000 parts of yellow sand, 200-230 parts of water and 10-20 parts of high-efficiency water reducing agent. The volume fraction of steel fibers is 0.2%-0.5%, and the volume fraction of boron fibers is 0.1%-0.2%; and the mass ratio of the high-dispersity carbon nanotubes is 0.1%-0.5%. Through reasonable compatibility and equivalent substitution of the three types of fibers, crack development of the radiation shielding concrete at a high temperature can be effectively restrained, and the anti-burst performance of the concrete at the high temperature is effectively improved. The boron fibers and the high-dispersity carbon nanotubes play roles in improving the radiation shielding performance of the concrete and maintaining the structural integrity of the concrete, and the radiation shielding performance of the structure at high temperature is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of radiation-proof concrete preparation, and particularly relates to anti-explosion radiation shielding concrete and a preparation method thereof. Background Art

[0002] Nuclear power technology is the main way to achieve clean energy. With the technological updates and iterations, the fourth-generation nuclear power technology has gradually entered the public eye, among which thorium-based reactor technology and gas-cooled reactor technology are typical representatives. Taking thorium-based reactors as an example, the internal operating temperature of a typical molten salt reactor is above 600°C, while the temperature of a traditional reactor is around 300°C. Therefore, how to improve the high-temperature performance of radiation-proof concrete has become a technical problem that urgently needs to be solved.

[0003] At present, the radiation protection technology of concrete is still mainly focused on improving the density of concrete and increasing the crystal water content. Crystal water is easily lost in high temperature environments, causing the density of concrete to decrease, cracking, and leading to engineering and technical problems such as a decrease in the radiation shielding ability of concrete. Drawing on the fracture toughening technology of ordinary high-performance concrete, fiber application is still the first choice for improving the comprehensive performance of radiation-proof concrete, but currently general engineering fibers are not resistant to high temperatures and have limited radiation shielding capabilities. High-performance concrete fiber reinforcement technology cannot be directly applied to high-temperature resistant radiation shielding concrete.

[0004] Therefore, how to provide a burst-resistant radiation shielding concrete and its preparation method that can be mass-produced to meet the needs of large-scale application of nuclear facilities is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0005] The present invention provides an explosion-resistant radiation shielding concrete and a preparation method thereof, aiming to enhance the explosion-proof and crack-proof performance of the radiation shielding concrete at high temperatures, maintain the overall stability of the structure, and minimize the influence of the high temperature environment on the comprehensive performance of the concrete.

[0006] In order to solve the above technical problems, the present invention includes the following technical solutions:

[0007] A burst-resistant radiation shielding concrete, wherein the components of the concrete are in a mass ratio of (kg / m 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 ratio 0.2%-0.5%, boron fiber volume ratio 0.1%-0.2%; high-dispersibility carbon nanotube mass ratio of 1‰-5‰.

[0009] Furthermore, the steel fiber is a cutting steel fiber or a microfilament steel fiber, and its density is 7.80 g / cm3 , tensile strength ≥2000MPa.

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

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

[0012] Furthermore, the preparation method of the highly dispersed carbon nanotubes is as follows: first, the carbon nanotubes are purified; then, rare earth metal nitrates and polyvinyl pyrrolidone are completely dispersed and dissolved in ethylene glycol by ultrasound to obtain an ethylene glycol solution of nitrates; secondly, the carbon nanotubes are added to the rare earth metal nitrate ethylene glycol solution and heated to reflux reaction; finally, the reaction product is washed with deionized water to neutrality, and then washed with alcohol and dried to obtain highly dispersed carbon nanotubes coated with rare earth metal oxides.

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

[0014] Step S1, adding cement, serpentine, yellow sand and granulated blast furnace slag powder into a mixer and stirring for 30 seconds;

[0015] Step S2, adding a high-efficiency water reducing agent and highly dispersible carbon nanotubes into water, and stirring until uniform;

[0016] Step S3, pouring a high-efficiency water reducing agent and a highly dispersible carbon nanotube aqueous solution into the dry mixture, and stirring for 120 to 240 seconds;

[0017] Step S4: adding steel fiber and boron fiber in sequence and stirring until uniform.

[0018] Furthermore, the cement is P.O42.5 ordinary Portland cement, the grades of granulated blast furnace slag powder 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 reducer is a polycarboxylic acid high-efficiency water reducer 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] The present invention provides a burst-resistant radiation shielding concrete, wherein the components of the concrete are in a mass ratio of (kg / m 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 ratio 0.2%-0.5%, boron fiber volume ratio 0.1%-0.2%; high-dispersibility carbon nanotube mass ratio of 1‰-5‰.

[0022] Steel fiber has high strength and can effectively bridge large-scale cracks and improve the comprehensive performance of concrete. However, steel fiber has limited heat resistance (melting point 1200℃), and is prone to thermal fatigue and stress relaxation at high temperatures, especially the tensile strength is significantly reduced. Under high temperatures, the interior of concrete is affected by factors such as gas expansion and aggregate-binder interface separation, which accelerates the development of cracks and gradually peels off the concrete. Therefore, the steel fiber has limited anti-burst ability at high temperatures. At room temperature, the commonly used synthetic fibers in concrete, such as PP (polypropylene) fiber and PVA (polyvinyl alcohol) fiber, have a low melting point (190℃~240℃), and the mechanical properties of concrete decrease significantly with the increase of temperature. The tensile strength of boron fiber can reach more than 3000MPa, and the melting point is above 2000℃. The performance decline is not obvious at high temperatures, and it can still effectively play the role of bridging cracks and reinforcing concrete, preventing the trend of concrete peeling. Boron fiber is inactive and resistant to acid and alkali corrosion. At the same time, the boron element has a large interception surface for neutrons, which plays a role in shielding and absorbing neutrons, and is suitable as a reinforcement material for anti-burst radiation shielding concrete.

[0023] Highly dispersed carbon nanotubes are added to concrete. Due to their small geometric size, they can effectively bridge micro cracks in concrete, and inhibit crack deterioration in the early stage of concrete expansion or water loss cracking. Although boron fiber has excellent performance, it is relatively expensive. The addition of highly dispersed carbon nanotubes has replaced part of the boron fiber, reducing the comprehensive preparation cost of explosion-proof radiation shielding concrete, with obvious economic benefits. In addition, the reduction in the amount of larger fibers also improves the flowability and construction performance of concrete.

[0024] The nano-cerium oxide particles covering the surface of carbon nanotubes are rare earth element oxides. Rare earth elements have a large thermal neutron absorption cross-section. The fast neutrons generated in the reactor become thermal neutrons after the energy is transferred to the hydrogen nucleus. Thermal neutrons are easily absorbed by the cerium oxide reaction, further improving the radiation shielding performance of concrete.

[0025] The reasonable combination and equivalent substitution of the three types of fibers can effectively curb the cracking of radiation shielding concrete at higher temperatures, effectively improve the anti-burst performance of concrete at high temperatures, and improve the mechanical properties of concrete. Boron fiber and highly dispersed carbon nanotubes 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of a neutron shielding test of explosion-resistant radiation shielding concrete and a preparation method thereof according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The following is a further detailed description of a burst-resistant radiation shielding concrete and a preparation method thereof provided by the present invention in conjunction with specific embodiments. The advantages and features of the present invention will become more apparent from the following description.

[0028] The explosion-proof radiation shielding concrete mix ratio proposed by the present invention is as follows: (kg / m 3 )

[0029]

[0030] The cement is PO 42.5 ordinary Portland cement, the grades of granulated blast furnace slag powder 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 reducer is a polycarboxylic acid high-efficiency water reducer with a water reduction rate of usually ≥30%, and the water is ordinary tap water.

[0031] The steel fiber is cut steel fiber or microfilament steel fiber with a density of 7.80g / cm 3 , the tensile strength is generally ≥2000MPa.

[0032] Boron fiber is generally prepared by hydrogen reduction and chemical vapor deposition process, usually tungsten boron fiber, thus ensuring comprehensive protection against neutrons and gamma rays.

[0033] Rare earth metal oxides are uniformly coated on the surface of carbon nanotubes to form a core-shell structure, thereby obtaining a uniform and structurally stable carbon nanotube composite material, namely, highly dispersed carbon nanotubes. The surface of carbon nanotubes is uniformly coated with cerium oxide nanoparticles. The inorganic oxide cerium oxide has a high hydrophilicity, which effectively improves the dispersion of carbon nanotubes in concrete. The surface oxide improves the compatibility of carbon nanotubes with concrete.

[0034] The preparation method of highly dispersed carbon nanotubes is as follows: first, the carbon nanotubes are purified; then rare earth metal nitrates and polyvinyl pyrrolidone are completely dispersed and dissolved in ethylene glycol by ultrasound to obtain an ethylene glycol solution of nitrates; finally, the carbon nanotubes are added to the ethylene glycol solution of rare earth metal nitrates and heated to reflux for reaction. 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.

[0035] The present 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 into a mixer and stir for 30 seconds;

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

[0038] Step 3: Pour the high-efficiency water reducing agent and the highly dispersed 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] Embodiment 1:

[0041] The mix ratio of common anti-blast radiation shielding concrete is as follows: (kg / m 3 )

[0042]

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

[0044]

[0045] The mix ratio of anti-blast radiation shielding concrete is as follows: (kg / m 3 )

[0046]

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

[0048]

[0049] The mix ratio of anti-blast radiation shielding concrete is as follows: (kg / m 3 )

[0050]

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

[0052]

[0053] Note: The 28d performance data of concrete are all measured after the specimens are thermally damaged and placed in a dry and ventilated place to cool to room temperature. The experimental heating rate is 4℃ / h and the constant temperature time is 2h.

[0054] refer to Figure 1 , the neutron flux after concrete shielding is measured by the following method:

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

[0056] The concrete sample is irradiated with a neutron source in the same energy range as the inner side of the molten salt reactor through the electron accelerator neutron source. 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 express several embodiments of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A burst-resistant radiation shielding concrete, characterized in that: The mass ratio of each component of the concrete is (kg / m 3 ): 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 ratio 0.2%-0.5%, boron fiber volume ratio 0.1%-0.2%; high-dispersibility carbon nanotube mass ratio of 1‰-5‰.

2. The explosion-resistant radiation shielding concrete according to claim 1, characterized in that: The steel fiber is a cutting steel fiber or a microfilament steel fiber, and its density is 7.80g / cm 3 , tensile strength ≥2000MPa.

3. The explosion-resistant radiation shielding concrete according to claim 1, characterized in that: The boron fiber is prepared by hydrogen reduction method and chemical vapor deposition process, and tungsten boron fiber is selected.

4. The explosion-resistant radiation shielding concrete according to claim 1, characterized in that: The highly dispersed carbon nanotubes are formed by uniformly coating the surface of the carbon nanotubes with rare earth metal oxides to form a core-shell structure, thereby obtaining a uniform carbon nanotube composite material with a stable structure.

5. The explosion-resistant radiation shielding concrete according to claim 4, characterized in that: The method for preparing the highly dispersed carbon nanotubes is as follows: first, purifying the carbon nanotubes; then completely dispersing and dissolving the rare earth metal nitrate and polyvinyl pyrrolidone in ethylene glycol by ultrasound to obtain an ethylene glycol solution of the nitrate; secondly, adding the carbon nanotubes into the rare earth metal nitrate ethylene glycol solution to perform a heating reflux reaction; finally, washing the reaction product with deionized water until it is neutral, washing with alcohol, and drying to obtain the highly dispersed carbon nanotubes coated with the rare earth metal oxide.

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

7. The preparation method according to claim 6, characterized in that: The cement is P.O42.5 ordinary Portland cement, the grades of granulated blast furnace slag powder 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 reducer is a polycarboxylic acid high-efficiency water reducer with a water reduction rate of ≥30%, and the water is ordinary tap water.

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